Copyright (c) 2013 Purdue University All rights reserved. http://docs.lib.purdue.edu Recent documents in Purdue e-Pubs en-us Fri, 24 May 2013 01:35:26 PDT 3600 http://docs.lib.purdue.edu/dissertations/AAI9622716 http://docs.lib.purdue.edu/dissertations/AAI9622716 Wed, 22 May 2013 15:54:31 PDT The purpose of this study was to deepen our understanding of therapeutic theory development through the interpretation and narrative description of the development of one of the fastest growing, internationally recognized schools of family therapy, solution-focused therapy. Qualitative interviews were conducted with each of the original developers of solution-focused therapy as well as several internationally known marriage and family therapists with rich associations to the Brief Family Therapy Center and solution-focused therapy. Themes and categories were inductively derived from the data. The major finding of the study was that certain climatic, interpersonal, and intrapersonal conditions and dynamics were needed for solution-focused therapy theory development to occur. In addition, two qualities of the founders' relationship to their surrounding environment were found to encourage solution-focused therapy theory development: a lack of accountability to funding sources and physical and theoretical isolation. Specific group activities were found to be an integral part of the theory development process. Reviews of submitted articles, conference presentations, and training of therapists enabled the founders to further articulate, disseminate, and modify existing theory. ^

]]> David James Kiser Social Work|Psychology, Clinical|Sociology, Individual and Family Studies http://docs.lib.purdue.edu/dissertations/AAI9622742 http://docs.lib.purdue.edu/dissertations/AAI9622742 Wed, 22 May 2013 15:54:31 PDT Using a neo-Weberian model this work focuses on the changing nature of the university in modern society. Particularly noted is the changing nature of what is understood to be knowledge and the role of technology adoption in the creation of this knowledge. I argue that modern knowledge is computationally oriented and favors the method of the natural sciences, a method that differs from the traditional discursive discovery of the classically-based liberal arts university.^ I also review the nature of the use of technology in modern social organizations. Technology is understood as at least in part the product of a political process flowing not from some independent purely technical path. In this way, some technology writers have argued that the new computing technology will serve to democratize society by making available inexpensive technology to all. Using Parkin's notion of closure, I show how prestigious institutions work to preserve their ascendancy by investing in leading edge research facilities which poorer institutions cannot match. Those institutions that fail to make this investment suffer declines in status.^ I review the literature surrounding a large number of indicators of university status. This examination reveals that there are only two satisfactory measures of status: external research income and number of post-doctoral students.^ Using comprehensive budgeting and descriptive data drawn every four years from the 3500 institutions of higher education in the United States over the period 1972-1992, I focus first on patterns distinguishing general classes of institution. I then focus particularly on the premier research institutions. By performing a comprehensive factor analysis and then using LISREL VIII, path diagrams are created to describe the relationships between key institutional measures and relative status. In both sets of analysis, those institutions which have systematically over-invested in computing technology have improved their status while those which under-invested have suffered reduced standing.^ I conclude that far from revolutionizing the hierarchical structure between universities, computing technology will serve to reinforce existing differences by offering yet another axis by which to exert superiority. ^

]]> William Gerard McCartney Library Science|Sociology, Social Structure and Development|Information Science|Education, Higher http://docs.lib.purdue.edu/dissertations/AAI9523414 http://docs.lib.purdue.edu/dissertations/AAI9523414 Wed, 22 May 2013 15:54:25 PDT The purpose of this study was to investigate the development of audiology students' professional values, traits and attitudes employing a cross-sectional design. In addition, an exploratory component of this study investigated the following characteristics of audiology students: reasons for selecting audiology as a career, professional plans and ambitions for the future and satisfaction with career choice. The effects of gender, age, marital status and grade level on these factors were examined. Two hundred and two students from 15 participating universities served as subjects. Subjects were administered a questionnaire consisting of four sections. The first two sections included demographic information, the reasons audiology was selected as a career, and professional plans and ambitions for the future. The third section, a professionalism scale, was designed to measure five attitudinal attributes of professionalism (i.e., sense of calling, belief in public service, belief in self-regulation, autonomy and using the professional organization as a major reference). The final section consisted of an uncertainty scale, measuring students stress from uncertainty in patient care. For the subjects studied, scores on the professionalism scale were the most professional for the attributes of sense of calling and belief in public service. The least professional responses were obtained for the attributes of autonomy, belief in self-regulation, and using the professional organization as a major reference. Multiple regression analyses revealed that satisfaction and doubts about career choice were significant predictors of professionalism. As hypothesized, stress from uncertainty was significantly negatively correlated with professionalism. This study suggests that although audiology is well on its way to meeting the requirements of a true profession, a number of issues regarding professionalism must be addressed during the recruiting and education of future practitioners. ^

]]> Leslie Elizabeth Neal Health Sciences, Audiology|Sociology, General http://docs.lib.purdue.edu/dissertations/AAI9523321 http://docs.lib.purdue.edu/dissertations/AAI9523321 Wed, 22 May 2013 15:54:24 PDT Within social service organizations the people at each level develop their own constructions of the programs and the clients. The social construction and cognitive dissonance perspectives were applied to service providers' constructions about their clients and the success of their program. Workers, staff, and volunteers from six non-profit organizations, with emphases on families and children, were interviewed about their views on their role, their clients, and the success of their program. Influences of time investment, client contact, position in the organization, and contact with other workers or volunteers were examined with respect to the constructions. Implications for performance of clients, staff, and evaluations of programs were discussed. ^

]]> Marilyn Sue Burton Chamberlin Social Work|Sociology, General|Sociology, Individual and Family Studies|Sociology, Public and Social Welfare http://docs.lib.purdue.edu/dissertations/AAI9512989 http://docs.lib.purdue.edu/dissertations/AAI9512989 Wed, 22 May 2013 15:54:23 PDT The purpose of this research is to develop a travel decision model using sociodemographics, travel characteristics, and psychographic factors and identify the different types of travel decision patterns in Japanese and West German travel markets. A secondary analysis of data from the Pleasure Travel Markets Survey for Japan and West Germany in 1989 was used. The major findings supported the proposition that models of a travel decision consisting of sociodemographics, travel characteristics and psychographics variables fit the observed data very well. Sociodemographics and travel characteristics were significantly related to psychographics variables and further predict the travel decision. The results also showed that travel decision pattern segmentation (travel philosophy--travel benefit sought--travel product preference) is a viable approach to identify different types of travel decision patterns in Japanese and West German travel markets. Implications of the findings are discussed and future research directions are suggested for this important area. ^

]]> Sheauhsing Hsieh Business Administration, Marketing|Recreation http://docs.lib.purdue.edu/dissertations/AAI9501661 http://docs.lib.purdue.edu/dissertations/AAI9501661 Wed, 22 May 2013 15:54:21 PDT This study analyzes the ideology of Reader's Digest during the Reagan/Bush era in the United States from 1980-1992. Recognizing the magazine's attempt to assert itself as a hegemonic force, the project combines the principles of Rhetorical Criticism and Cultural Studies to produce a composite view of the ideology of Reader's Digest, especially in reference to selected issues. After providing a review of the relevant literature on the subject, the study outlines the development of cultural/ideological studies both within and outside the field of Communication. The paper summarizes the writings of Ernesto Laclau and Chantal Mouffe relevant to cultural/ideological studies, then explains "articulation theory" as the critical methodology to be employed. Chapter Three provides a historical overview of the magazine as an institution, then applies Edward S. Herman and Noam Chomsky's "Propaganda Model" to the organization. Selected topics for textual analysis include: Representations of Women, Representations of Communism and Its Adherents, and Representations of Science and Technology. Finally, the overall ideology of the magazine is demonstrated to be based in promotion of social, political, and psychological inertia. ^

]]> Shawny Anderson American Studies|Mass Communications http://docs.lib.purdue.edu/dissertations/AAI9215705 http://docs.lib.purdue.edu/dissertations/AAI9215705 Wed, 22 May 2013 15:54:13 PDT Aconitase is the second enzyme in the citric acid cycle. It catalyzes the reversible dehydration of citrate to cis-aconitate and the consequent hydration of cis-aconitate. A full length cDNA encoding porcine heart aconitase has been cloned and sequenced. The 2700-base pair (bp) cDNA contains a 29-bp 5$\sp\prime$ untranslated region, a 2343-bp coding segment, and a 327-bp 3$\sp\prime$ untranslated region. The porcine heart enzyme is synthesized as a precursor containing a mitochondrial targeting sequence of 27 amino acid residues which is cleaved to yield a mature enzyme of 754 amino acids, M$\sb{\rm r}$ = 82,754, having a blocked amino terminus. The NH$\sb2$-terminal pyroglutamyl residue of the mature enzyme was identified by fast atom bombardment mass spectrometry and sequence analysis of an NH$\sb2$-terminal peptide. A cDNA encoding mature porcine heart aconitase was over-expressed in Escherichia coli under the control of a phage T7 promoter. Mature recombinant aconitase purified from E. coli was identical to the enzyme from pig and beef heart in size, (3Fe-4S) and (4Fe-4S) cluster structure and enzymatic activity. Nine amino acid residues in close proximity to the Fe-S cluster and bound substrate were replaced by site-directed mutagenesis. Fe-S cluster environment as indicated by the EPR spectrum, tight binding of substrate and enzymatic activity were compared for the mutant and wild type enzymes. Significant perturbations were detected for all of the mutant enzymes. Replacements for Asp$\sp{100}$, His$\sp{101}$, Asp$\sp{165}$, Arg$\sp{580}$ and Ser$\sp{642}$ result in a 10$\sp3$ to 10$\sp5$-fold drop in activity, which suggests that these residues are involved in critical aspects of the reaction. Arg$\sp{580}$ appears to be a key residue for substrate binding, as shown by a 30-fold increased K$\sb{\rm m}$ and loss of tight substrate binding. Results of mutagenesis support the interpretation of the X-ray model, namely that Asp$\sp{100}$ and His$\sp{101}$ may form an ion pair for elimination of the substrate hydroxyl and Ser$\sp{642}$ may function as a general base for proton abstraction from citrate or isocitrate in the dehydration step and protonation of cis-aconitate in the hydration step. Asp$\sp{165}$ appears to play a critical role in the interaction of Fe$\sb{\rm a}$ with substrate.^ The iron-responsive element-like RNA sequence at the 5$\sp\prime$ end of porcine mitochondrial aconitase has been demonstrated to be bound by iron-responsive element-binding protein. Bovine cytosolic aconitase has been shown to bind iron-responsive element specifically. These results suggest that cytosolic aconitase may be an iron-responsive element-binding protein, and the translation of mitochondrial aconitase mRNA may be subject to iron-dependent regulation. ^

]]> Limin Zheng Chemistry, Biochemistry http://docs.lib.purdue.edu/dissertations/AAI9132457 http://docs.lib.purdue.edu/dissertations/AAI9132457 Wed, 22 May 2013 15:54:11 PDT The purpose of this research was to examine the multiple factors involved in balancing the demands of work and family integration by dual-career couples. The research investigated the relationships among gender and parental status on integrating work and family life by examining: determinants of multiple role stress, perceptions of supportive organizational practices, career salience, integration of work with family, enabling processes, and satisfaction.^ A sample of 496 individuals (248 couples), who were selected randomly, participated in the two-phased dual-career survey research study. The participants were selected primarily from three large midwestern companies. All subjects were representative of dual-career couples.^ Twelve hypotheses were generated to investigate the relationships among gender and parental status on work and family integration of dual-career couples. Results of the research indicated that there were significant gender differences in determinants of multiple role stress, integration of work with family, and in perceptions of supportive organizational practices. There were significant differences in regard to parental status on determinants of multiple role stress, enabling processes, and work and family integration. No significant difference was found in relationship to gender or parental status on career salience and satisfaction reported by members of dual-career couples.^ Conclusions indicated that although there were some gender and parental status differences, members of dual-career couples appear to view many of the work and family factors involved in balancing this type of lifestyle similarly. However, what varies is the degree of intensity and magnitude experienced by the individual. Dual-career couples do encounter stress and conflict, but also report a great deal of satisfaction in both career and family, where the associated rewards of this type of lifestyle appear to outweigh the dilemmas. ^

]]> Elaine Marie Young Hicks Education, Guidance and Counseling|Sociology, Individual and Family Studies http://docs.lib.purdue.edu/dissertations/AAI9132441 http://docs.lib.purdue.edu/dissertations/AAI9132441 Wed, 22 May 2013 15:54:10 PDT The double is a ubiquitous figure in literature that has been traditionally interpreted as representing the divided, dual nature of man. According to Ralph Tymms, the concept of the double grew out of an atavistic belief in the magic of dualism. The theme is a hybrid one that stems from both the matter-of-fact, physical resemblance between two people and an irrational feeling of awe evoked by the confrontation of two identical persons.^ The German romantics took up the concept of the double and used it extensively in order to express the ambiguities that they found to be inherent in the nature of man. Much of the critical theory on the double or Doppelganger treats it as essentially a realist strategy that can depict the inner being or psychological reality of characters. While the general theory of the double is well-advanced, there is little new theory available to explain the remarkable presence of doubles in twentieth-century literature, particularly in the work of such writers as Machado de Assis, Fuentes and Nabokov, whose fundamental concerns tend not to be with the human personality or the inner self, but rather with issues of writing and language, and of abstraction rather than realism and representation.^ This study found that in three twentieth-century novels, Machado de Assis' Dom Casmurro, Vladimir Nabokov's Lolita, and Carlos Fuentes' Aura, the double can be shown to function in a transgressive and subversive way to undermine the text's realistic surface. The result of this use of doubling is a richer, polivalent reading, as the text can be read simultaneously as representional, realist work, and as a formal, poetic artifact, and construct of words. ^

]]> Leslie Thomas Dale Literature, Comparative|Literature, Latin American|Literature, American http://docs.lib.purdue.edu/dissertations/AAI9008690 http://docs.lib.purdue.edu/dissertations/AAI9008690 Wed, 22 May 2013 15:54:05 PDT A logical analysis of mass spectrometric scan modes is performed which reveals the full set of experiments available in multi-stage mass spectrometry. The analysis utilizes a symbolism and terminology which helps to provide an organizational scheme for representation and classification of the wide variety of experiments which exist. Data manipulation techniques which operate on data of different order and dimensionality to generate other forms of data are discussed and demonstrated.^ The analysis reveals several new types of scan modes including a last remaining MS/MS scan type referred to as the functional relationship scan, a last remaining MS/MS/MS scan having mass dimensionality of one referred to as the selective neutral-loss scan, and several MS/MS/MS scans which have two mass dimensions.^ Several new types of multi-stage mass spectrometers are described. Hybrid mass spectrometers are discussed in general and two examples are discussed in detail. A second generation hybrid BEqQ instrument is described along with the necessary electrical and computer interfacing required for its operation. The performance of the instrument for MS/MS/MS experiments is demonstrated using several examples of the various scans for obtaining sequence specific information about peptide samples. A detailed study of ion injection into a quadrupole ion trap operated in the mass instability mode resulted in the ability to construct a novel hybrid instrument. The instrument joins together a high resolution magnetic (B) and electric (E) sector mass spectrometer to a mass analyzing quadrupole ion trap (T) to form the first BET hybrid instrument. The advantages and performance of this instrument are described.^ The shortcomings of the hybrid BEqQ for performing some MS/MS/MS experiments are found to be overcome by an instrument which joins three mass analyzing and two rf-only quadrupole devices in tandem. This instrument is found to be quite suitable for implementing all the various MS/MS/MS scan modes using a relatively simple and inexpensive data system which is also described. ^

]]> Jae Curtis Schwartz Chemistry, Analytical http://docs.lib.purdue.edu/dissertations/AAI9008687 http://docs.lib.purdue.edu/dissertations/AAI9008687 Wed, 22 May 2013 15:54:04 PDT Low-energy polyatomic ion/surface collision phenomena and peptide sequencing are examined by tandem mass spectroscopy. Instruments constructed for these studies include: a new tandem time-of-flight instrument, an in-line ion/surface collision device, and a pentaquadrupole instrument.^ Fundamental aspects of ion/surface collisions are examined such as the effect of collision energy on internal energy deposition, ion/surface reactive collisions and low-energy sputtering. Internal energy deposition increases with collision energy in all instruments with approximately 10-15% of the collision energy deposited as internal energy. At low collision energies ion/surface reactions compete with dissociation of the parent ion. At collision energies above 100 eV, sputtering of surface adsorbates is the dominant process. The nature of the target is important even at a vacuum of 10$\sp{-6}$ torr, where all surfaces are expected to be unclean. Stainless steel-like targets are found to deposit more internal energy and produce more ion/surface reaction products and sputtering products than aluminum targets. Graphite targets produce only dissociation of CF$\sbsp {3}{+}$ ions when attempting to sputter surface adsorbates.^ An analytical approach to peptide sequencing is taken to obtain the maximum and most interpretable sequence information using both MS/MS and MS/MS/MS scan modes. More abundant fragmentation is observed using ion/surface collisions compared to gas phase collisions for several large peptides. MS/MS/MS scan modes are applied to simplify sequencing by allowing only one type of sequence ion, e.g. N-terminal ions, to be observed. The reaction intermediate scan produces the simplest spectra with no interfering ions and provides the best detection limits. The selective parent scan produces the most easily interpretable spectra, but interferences are expected in mixture analysis. The pentaquadrupole instrument produces higher quality MS/MS/MS data than a hybrid BEQQ instrument.^ MS/MS studies of target gas effects in collision activated dissociation in both low- and high-energy collisions show a dependence on the parent ion mass to the target mass in low-energy experiments and very little effect in high-energy experiments. ^

]]> Kevin Lynn Schey Chemistry, Analytical http://docs.lib.purdue.edu/dissertations/AAI8825537 http://docs.lib.purdue.edu/dissertations/AAI8825537 Wed, 22 May 2013 15:54:00 PDT The thrust of this research is to develop and validate a systematic technique for pilot-optimal control/display synthesis in complex, closed-loop manual control tasks. The suggested methodology makes extensive use of an Optimal Control Model of human behavior, both for synthesis as well as analysis. Therefore, the use of the Optimal Control Modeling approach to adequately predict the effects of control/display interaction on human performance and workload, is first validated by performing a detailed model-based study of a set of configurations previously evaluated in an in-flight experimental study.^ The mathematical formulation of the Cooperative Control Synthesis technique is then extended to allow for simultaneously augmenting the display dynamics as well as plant or controlled element dynamics. The first order necessary conditions for the optimality of the control/display augmentation control laws are derived and a numerical solution algorithm is developed to solve for these control laws.^ The methodology is exercised to synthesize control and display augmentation in a compensatory tracking task with a generic controlled element. Analytical evaluations of the designs indicate the applicability of the methodology to meet pilot-centered requirements and to provide a task specific, systematic trade-off between control and display augmentation. An extensive real-time man-in-the-loop simulation study is performed to validate the results from the methodology. Excellent agreement is obtained between these experimental and analytical results. The importance of adjusting the sensitivity of the controlled plant to make it acceptable to the human controller was vividly brought forth in the experimental study.^ Finally, the utility of the methodology is demonstrated by synthesizing control-display designs in the longitudinal approach and landing task for a modern, statically unstable fighter-type aircraft. Analytical evaluations of the resulting designs indicate that the methodology provides a systematic approach to synthesizing pilot-optimal control and display augmentation within other system constraints such as display time delay in Head-up display, and control surface actuation limits. ^

]]> Sanjay Garg Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI8300963 http://docs.lib.purdue.edu/dissertations/AAI8300963 Wed, 22 May 2013 15:53:50 PDT Part I. Employing cis,trans-puleganolide (1), derived from optically active (+)-pulegone, as starting material an efficient stereospecific synthesis of (-)-(alpha)-acoradiene (2) was accomplished. The synthesis features, as a key step, the alkylation of 1 with 1-iodo-3,3-ethylenedioxybutane. An elimination reaction performed on the alkylated lactone with t-butoxide introduces the isopropenyl group. Esterification of the resulting acid and Claisen condensation with butoxide gives the desired spirodecane skeleton. Upon formation of the enol ether of the spirodione followed by hydride reduction and acid workup a dienone 3 is afforded. Reaction of 3 with methylene-tripenylphosphorane and reduction of the resulting triene with lithium in ammonia affords the diene 2. The synthesis of 2 also constitutes a formal synthesis of (-)-(alpha)-cedrene.^ Part II. A total synthesis of (beta)-santalol (1) using camphene sultone (2) as starting material is described. Alkylation of 2 with the tetrahydropyranyl ether of 2-bromoethanol followed by sequential treatment with phenyllithium and 6% sodium amalagam affords a desulfurized monoprotected diol. Dehydration, deprotection and oxidation produces an aldehyde which has been previously transformed into 1 in a highly stereoselective manner.^ Part III. The reaction of several (beta)-disubstituted conjugated carboxylic acids and trans-cinnamic acid gave fair to poor yields of (alpha)-chloro-(beta)-lactones when allowed to react with hypochlorous acid using a two phase system. In cases of (beta)-monoalkylsubstituted conjugated acids the major isolated product was chlorohydrin.^

]]> DENNIS WILLIAM SOLAS Chemistry, Organic http://docs.lib.purdue.edu/dissertations/AAI8113639 http://docs.lib.purdue.edu/dissertations/AAI8113639 Wed, 22 May 2013 15:53:45 PDT This study is a feminist reading of the novels of Jessie Fauset, Nella Larsen, and Zora Neale Hurston that focuses on a singularly important, often overlooked, strain in their fiction--their studied preoccupation with the myriad shadings of womanhood. The study inclines heavily toward a discussion of female character, especially the psychology of the black female. Each writer began her career aware of the predominant images or stereotypes of the black woman as sensual, primitive siren, on the one hand, and as the "mammy," the larger-than-life matriarch on the other. Each wrote in conscious opposition to these stereotypes, attempting to create new, more complete images of women that would represent alternatives to these traditional images. What they attempted was not uniformly commensurate with what they achieved, however, for social attitudes about women's roles, as well as artistic censorship by critics and publishers, exerted pressure on the writers that often resulted in their retreat to more conventional statements about womanhood.^ The study is divided into six chapters. The first chapter provides a general background of the factors that influenced these writers' treatment of the woman question. For example, aspects of their lives clearly influence their central fictional concerns. Each led a life that departed from conventional expectations of women. None became a mother and none seemed to place a high premium on marriage. Social attitudes about women reflected in certain "little magazines" of the Harlem Renaissance period additionally influence these women's treatment of the female.^ The second chapter analyzes the Harlem Renaissance, its development and character. It outlines the controversy over the nature and function of black literature that factionalized the movement's participants and perhaps initiated its decline.^ The third chapter examines Fauset's treatment of the black female character and demonstrates that her writings in The Crisis magazine--essays and short stories--as well as her foreign lecture tours are alike consistent with her paramount fictional concerns.^ The fourth chapter examines Nella Larsen's portrayal of the female character, a portrayal demonstrating that her knowledge of female psychology is more sophisticated than Fauset's, her characterization, stronger, more complex. Larsen openly indicts the three institutions which have most effectively impeded female development and autonomy--education, marriage, and religion--and satirizes her characters who capitulate to these institutions.^ The fifth chapter discusses Zora Neale Hurston, who surpasses both Fauset and Larsen in chattering those traditions, institutions, and value systems which have historically oppressed women and kept them from developing into full, independent beings. Moreover, Hurston's works, more clearly than either Fauset's or Larsen's, transcend the particulars of the woman question to embrace more universal and humanistic concerns.^ The last chapter summarizes the major points of the study and briefly discusses its implications. Additionally, the chapter attempts to establish Fauset, Larsen, and Hurston as pioneers in the development of a black female literary tradition and connects them with contemporary black women novelists whose fictional preoccupation is also the sensitive exploration of the dynamics of black womanhood. ^

]]> DEBORAH EDITH MCDOWELL Literature, American http://docs.lib.purdue.edu/dissertations/AAI7517242 http://docs.lib.purdue.edu/dissertations/AAI7517242 Wed, 22 May 2013 15:53:36 PDT ERIC MICHAEL MALSTROM Engineering, Industrial http://docs.lib.purdue.edu/dissertations/AAI7426688 http://docs.lib.purdue.edu/dissertations/AAI7426688 Wed, 22 May 2013 15:53:34 PDT LOU ANN BLEAKLEY Education, General http://docs.lib.purdue.edu/dissertations/AAI7328029 http://docs.lib.purdue.edu/dissertations/AAI7328029 Wed, 22 May 2013 15:53:31 PDT GEORGE THOMAS KARTSOUNES Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI7305992 http://docs.lib.purdue.edu/dissertations/AAI7305992 Wed, 22 May 2013 15:53:30 PDT JOHN ROBERT BITTNER Speech Communication http://docs.lib.purdue.edu/dissertations/AAI7109463 http://docs.lib.purdue.edu/dissertations/AAI7109463 Wed, 22 May 2013 15:53:28 PDT Abstract Not Available^

]]> JAMES LAWRENCE SCHOTT Education, Administration http://docs.lib.purdue.edu/dissertations/AAI6907420 http://docs.lib.purdue.edu/dissertations/AAI6907420 Wed, 22 May 2013 15:53:24 PDT C. LEONARD BENNETT Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI6812538 http://docs.lib.purdue.edu/dissertations/AAI6812538 Wed, 22 May 2013 15:53:23 PDT UMAKANT DASH Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI6505015 http://docs.lib.purdue.edu/dissertations/AAI6505015 Wed, 22 May 2013 15:53:19 PDT ULYSSES HUNTER Mathematics http://docs.lib.purdue.edu/dissertations/AAI6408716 http://docs.lib.purdue.edu/dissertations/AAI6408716 Wed, 22 May 2013 15:53:18 PDT LARRY EUGENE SNYDER Mathematics http://docs.lib.purdue.edu/dissertations/AAI6408624 http://docs.lib.purdue.edu/dissertations/AAI6408624 Wed, 22 May 2013 15:53:17 PDT HANS HUGO AMMANN Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI5801815 http://docs.lib.purdue.edu/dissertations/AAI5801815 Wed, 22 May 2013 15:53:13 PDT ERWIN J STEGMAN Psychology, Clinical http://docs.lib.purdue.edu/dissertations/AAI3556865 http://docs.lib.purdue.edu/dissertations/AAI3556865 Wed, 22 May 2013 15:53:12 PDT Minimal attention has been devoted to examining the dimensionality of self-control. The present study tested a multidimensional model of self-control in which dimensions were based on the nature of the behavior required (i.e., persistence, initiation, cessation, or prevention). A total of 336 undergraduates completed measures of self-control and psychological well-being. Seventy-four of these participants completed behavioral self-control tasks representing the proposed subtypes. Participants' GPAs were obtained from the Registrar. Stop self-control was inversely related to previously-validated measures of persistence (β = -.61, p = .010) and prevention (β = -.56, p = .040) self-control and demonstrated differential predictive ability of persistence and prevention compared to the other proposed subtypes. Initiation self-control was inversely related to life satisfaction (β = -.35, p = .012) and demonstrated differential predictive ability of life satisfaction compared to stop self-control. These results were interpreted with caution due to inadequate power and questionable validity of several of the behavioral self-control tasks. Both handgrip persistence (r = -.25, p = .033) and blinking prevention (r = -.29, p = .023) were associated with depression. These pairwise correlations were not significantly different from each other, suggesting that no conceptual distinction should be made between persistence and prevention self-control. Confirmatory factor analyses of self-report data revealed that items clustered based on domain rather than on type of behavior required for self-control exertion. Thus, the structure of self-control remains unclear. Limitations of the present study and implications for future research are discussed.^

]]> Chloe Ann Tunze Psychology, Social|Psychology, General|Psychology, Clinical http://docs.lib.purdue.edu/dissertations/AAI3556868 http://docs.lib.purdue.edu/dissertations/AAI3556868 Wed, 22 May 2013 15:53:12 PDT Ecological momentary assessment (EMA) has been asserted by proponents of the technique as being superior to standard paper-and-pencil measurements in terms of the reliability and validity of the information obtained; however, this claim has not yet been fully evaluated in the literature. Accordingly, the purpose of this study was to evaluate one aspect of this assertion by comparing the utility of EMA and retrospective measures of depressive symptoms in predicting health-relevant biological and behavioral outcomes. It was hypothesized that (1) the EMA measure will have better predictive utility when examining objective sleep quality (a biological outcome), and that (2) the retrospective measure will have better predictive utility when examining blood donation intention (a behavioral outcome). Ninety-six undergraduate females participated in this 2-week study. Depressive symptoms were measured momentarily and retrospectively using the Center for Epidemiological Studies-Depression Scale (CES-D). The biological outcome was assessed by actigraphy, whereas the behavioral outcome was measured via a self-report questionnaire. Unfortunately, it was not possible to fully test these hypotheses due to the failure to observe relationships between the predictor variables and the outcomes. The reported results, although limited, did not provide support for the hypotheses. Supplemental analyses revealed a moderate to high amount of shared variance between the EMA and retrospective measures, a similar extent of random error in both measures, and potentially a greater degree of systematic error in the retrospective measure. Due to the paucity of literature examining the claim of superior reliability and validity of EMA versus retrospective measures, as well as the failure of the current study to evaluate this assertion sufficiently, it appears that this claim remains unfounded. Therefore, suggestions for future research are provided.^

]]> Desiree Joy Zielke Psychology, Clinical http://docs.lib.purdue.edu/dissertations/AAI3556744 http://docs.lib.purdue.edu/dissertations/AAI3556744 Wed, 22 May 2013 15:53:11 PDT This research focuses on the climate and basin evolution of the southwestern United States from the late Paleocene to the early Eocene, from approximately 60 to 50 million years ago. I applied geochemical proxy techniques, including conventional light stable isotope measurements of multiple substrates, as well as the novel "clumped isotope" paleothermometry technique, to investigate this subject. ^ The early Paleogene topography of western North America was very different from today, with a major mountain range known as the Sevier Thrust Belt existing in the area now occupied by the Basin and Range physiographic province. The foreland to the east of this orogenic belt was divided into a series of endorheic basins occupied by large lakes. The lake which existed in central Utah, referred to today as paleo-Lake Flagstaff from the formation of the same name which records it, has previously been regarded as an arm of paleo-Lake Uinta which existed to the northeast. Using carbon and oxygen isotope measurements of authigenic carbonate sediments, I have confirmed that the sediments of the Flagstaff Formation were the product of a single, large lake. However, the isotopic signatures of Lakes Flagstaff and Uinta are distinct, indicating that they were not connected during this interval. Instead, Lake Flagstaff may have undergone hydrologic connection with paleo-Lake Claron to the southwest. ^ Utilizing the clumped isotope paleothermometer with soil carbonate nodules, I investigated the climate conditions of central Utah across the Paleocene-Eocene boundary, one of the warmest intervals of the past 65 million years. The temperature estimates I produced using this method are considerably warmer than those previously generated for the region using fossil botanical indices. This is partially a product of the differing biases inherent to each estimate, but also indicates that mid-latitude continental temperatures may have been much warmer during the early Eocene than previously thought, addressing one of the major existing questions regarding climate during this epoch. ^ Finally, I analyzed hydrogen isotope ratios of authigenic clay minerals from the same soils spanning the Paleocene-Eocene boundary. At this site, the proxy records time-averaged hydrologic conditions, which can be useful in studies of paleotopographic evolution.^

]]> Justin H VanDeVelde Geology|Climate Change|Paleoclimate Science|Geochemistry http://docs.lib.purdue.edu/dissertations/AAI3556861 http://docs.lib.purdue.edu/dissertations/AAI3556861 Wed, 22 May 2013 15:53:11 PDT My dissertation argues for the existence of a "political anthropology" in the work of Gilles Deleuze. However, this perspective is by no means an obvious one. Thus, my project is based on a certain way of approaching Deleuze's thought. ^ I began by investigating two recurring themes in Deleuze's work: his critique of psychoanalysis and claim Anglo-American literature is superior to French and German literature. Precisely these lines of inquiry led me to a "political anthropology" in the thought of Deleuze. His critique of psychoanalysis and praise for Anglo-American bear on different conceptions of human nature, as well as the respective understandings of political activity they support. I argue this constitutes the most fundamental strength of Deleuze's thought, the major contemporary significance of his work. This becomes evident by examining the influence of the English writer D.H. Lawrence on Deleuze. ^ On almost every occasion Deleuze criticizes psychoanalysis or praises Anglo-American literature, he refers to Lawrence's Fantasia of the Unconscious and Studies in Classic American Literature. Deleuze can only thus be fully understood through Lawrence. Lawrence's critique of psychoanalysis and praise for classic American literature revolve around conceptions of human nature. Exploring these accounts and tracing Lawrence's commitments brings to light the philosophical anthropology implicit in the work of Deleuze, as well as its political implications. ^ On the one hand, both psychoanalysis and Franco-Germanic literature suppose a conception of human nature where the mind is given priority over the body, individuals are conceived on the model of self-subsistent substances, community is conceived as a collection of substances, and the basis of relations between individuals and community are common goals and mutual aspirations—such that consensus represents the highest goal of political activity. On the other hand, central to schizoanalysis and "Anglo-American literature" is a philosophical anthropology where the mind is not given priority over the body, individuals are conceived as unique sets of relations—what Spinoza calls "bodies"—community is conceived as wider, further-reaching sets of relations than individuals, and the basis of relations between individuals and community is sympathy—such that the goal of political activity consists in the production of shared thoughts, perceptions, and feelings. A framework such as this—where one's political commitments are tethered to a conception of human nature—diverges sharply from the mainstream of contemporary political philosophy. ^ Refraining from making strong claims regarding the nature of the good life, morality, etc., based on robust conceptions of personhood, is indicative of an attempted neutrality in contemporary political thought. Tied to the liberal tradition, as an ideal this neutrality nonetheless arises from and is based on an implicit account of human nature, one similar to that criticized by Deleuze in psychoanalysis and Franco-Germanic literature. Insofar as increasing social and political polarity characterizes the contemporary situation, the account of human nature on which this ideal is based seems thoroughly misguided. ^ Hence, Deleuze's work can be understood as contributing to the project of a political anthropology, versus the mainstream of contemporary political thought. The fact this contribution takes shape in terms of Lawrence's thought on psychoanalysis and classic American literature is significant. ^ On these issues Lawrence is conservative, bizarrely so when considered in relation to Deleuze. In terms of psychoanalysis, social and familial relations, Lawrence defends thoroughly traditional gender roles. Worse still, with respect to both psychoanalysis and classic American literature, his emphasis on the body and the importance of strong communal relations seems indicative of proto-national socialist sympathies. Rather than becoming embarrassed by or dismissing these tendencies in Lawrence, the merit of Deleuze's political anthropological project consists in taking these seriously, considering what is plausible in these seemingly antiquated lines of thought. ^ When taken up by Deleuze, the merit of Lawrence's thought consists in making sense of the strong contemporary backlash against neutrality with respect to claims regarding the nature of human existence. This is precisely because of the conservative lines of thought that permeate Lawrence's work. ^ Only by engaging in these lines of thought can one hope to combat them, understanding the allure of sexism, nationalism, fundamentalism, etc.—all forms of conservatism in terms of which the backlash against liberalism develops. These should not be understood as deviations from universal norms on which liberal thought is based. Insofar as liberal ideals are themselves rooted in a conception of human nature, this backlash should be understood in terms of philosophical anthropology. ^ In terms of their emphasis on the body and reconceptualization of individuality, community, and relations between the two, the thought of Lawrence and Deleuze makes sense of this tendency and these movements, pointing towards a political anthropology in terms of which they can be better understood and addressed. (Abstract shortened by UMI.)^

]]> Rockwell Franklin Clancy Philosophy|Literature, American|Literature, English|Psychology, General http://docs.lib.purdue.edu/dissertations/AAI3556714 http://docs.lib.purdue.edu/dissertations/AAI3556714 Wed, 22 May 2013 15:53:10 PDT According to a recent survey conducted by the Commonwealth Fund cite, The total spending in the U.S. healthcare system is the highest in the world, accounting for 16% of the U.S. GDP. The per capita healthcare spending in the U.S. is 2-3 times as much as other industrialized countries, but the outcome has yet to reflect this. By no means, we should put the blame solely on the total healthcare spending. It is always difficult to set aside between being economically optimal and being morally correct. Therefore, instead of controlling the total healthcare spending, it is more meaningful to study the extra expenditure, associated with each financing structure, which has no effect on improving the wellness of the patients. In this paper, we name such cost the structure cost. One can view the structure cost as the waste incurred by healthcare financing structure. We consider two types of structure costs: over-utilization cost incurred by healthcare providers and overhead cost incurred by private insurers. Our goal is to investigate the possible reduction of structure cost via the implementation of different healthcare financing mechanisms with the participation of the government. ^ In this thesis, we investigate three mechanisms, all of which can be modeled as two-player Stackelberg games. In the first mechanism, the government provides a universal health care plan and the private insurer subsequently designs a supplementary plan. With the second mechanism, the government reimburses individual out-of-pocket healthcare spending via channels such as tax return. With the third mechanism, the government subsidizes individuals who purchase the private insurance plan. In each game, the government is the leader and the private insurance company is the follower. The government's objective is to minimize the structure cost subject to possible budgetary constraint. The private insurance company's objective is to maximize its gross profit. ^ A particular risk group will decide the exogenous factors such as risk preference coefficient, insurance demand and its elasticity. We evaluate the structure cost as a percentage ratio over the basic medical cost given the input parameters. As a case study, we use the data from the RAND HIE experiment in outpatient acute, outpatient mental and dental care. We estimate the parameters in our model from available RAND data and the health economic and service literature. We analyze each Stackelberg game and compare the three mechanisms numerically. Our models are formulated as bi-level non-convex programming problems. We adapt the Mitsos' algorithm to solve them globally. With our framework, we expect to provide some insightful suggestions into the system design.^

]]> Zhen Zhu Health Sciences, Health Care Management|Operations Research http://docs.lib.purdue.edu/dissertations/AAI3556713 http://docs.lib.purdue.edu/dissertations/AAI3556713 Wed, 22 May 2013 15:53:10 PDT The ϒ(nS) production cross sections are measured using a data sample corresponding to an integrated luminosity of 35.8±1.4 pb⁻¹ of proton-proton collisions at s = 7 TeV, collected with the CMS detector at the CERN LHC. Integrated over the transverse momentum range p_T < 50 GeV/c and rapidity range :y: < 2.4, and assuming unpolarized ϒ(nS) production, the products of the ϒ(nS) production cross sections and branching fractions are spp→U 1SX˙ B&parl0;U&parl0;1S&parr0;→m⁺ m^-&parr0;=&parl0;8.55±0.05^+0.74 -0.71±0.34&parr0; nb, spp→U 2SX˙B&parl0; U&parl0;2S&parr0;→m⁺m ^-&parr0;=&parl0;2.21±0.03^+0.21-0 .20±0.09&parr0;nb, spp→U 3SX˙B&parl0; U&parl0;3S&parr0;→m⁺m ^-&parr0;=&parl0;1.11±0.02^+0.12-0 .11±0.04&parr0;nb, where the first uncertainty is statistical, the second is systematic, and the third is associated with the estimation of the integrated luminosity of the data sample. The ϒ(1S), ϒ(2S), and ϒ(3S) differential cross sections in transverse momentum and rapidity and the cross section ratios ϒ(nS)/ϒ(mS) are presented. Cross section measurements performed within a restricted muon kinematic range and not corrected for the acceptance are also provided. These measurements are independent of ϒ(nS) polarization assumptions.^

]]> Yu Zheng Physics, Elementary Particles and High Energy http://docs.lib.purdue.edu/dissertations/AAI3556712 http://docs.lib.purdue.edu/dissertations/AAI3556712 Wed, 22 May 2013 15:53:09 PDT The huge amount of information from the Internet and other digital repositories has become an obstacle for people to obtain and organize information. This demands different types of effective information retrieval solutions. However, many information retrieval applications with learning techniques involve ambiguous information. In this thesis, I focus mainly on solving three important problems in this topic, which include the label ambiguity problem, the label incompleteness problem and some ambiguity problems in social media. ^ The label ambiguity problem exists when users are interested only in parts of each object. For example, in text mining, it is highly possible that only some parts of each webpage are related to a topic/label. In this case, if each webpage is represented by just one feature vector, the features of relevant parts may be buried by those of the irrelevant parts. ^ The label incompleteness problem exists in cases when only an incomplete list of labels in the training set is available. For example, in webpage classification for sports, it might be possible to obtain a partial list of common classes, such as football, cycling, and swimming; but the webpages on new topics can appear as the data arrives. As a result, the ambiguity problem arises since the obtained classifier is normally not applicable to new categories. ^ In social media, information, such as sentiments towards a product, spreads in complex social networks. In this scenario, the problem of ambiguity also exists. For example, microblog sites like Twitter require that the length of each post be limited, and this limitation on the length of posts brings some extent of ambiguity to the learning problem. ^ Although in the aforementioned three problems, only some ambiguous supervision is available, the ambiguity problem can be alleviated by leveraging some valuable partial knowledge. For example, in the label ambiguity problem of text mining, some structure information, such as link relationships may exist. These link relationships (partial knowledge) can be used to help design the classifiers more accurately. In this thesis, I investigate how to utilize different kinds of partial knowledge to alleviate the problem of ambiguity in different scenarios. ^

]]> Dan Zhang Computer Science http://docs.lib.purdue.edu/dissertations/AAI3556710 http://docs.lib.purdue.edu/dissertations/AAI3556710 Wed, 22 May 2013 15:53:08 PDT Data in many scientific and engineering applications are structured and contain multiple aspects. There are two significant challenges for predictive modeling for these data. The first challenge is how to model nonlinear relationships between different entities in the data, and the second challenge is how to make scalable inference for predictive models. To address these challenges, we use Gaussian processes to provide data modeling solutions and develop efficient inference algorithms by exploiting the structures within the data. First, we present a sparse Gaussian process regression method, GPLasso, which uses KL divergence minimization and ℓ₁ penalization to explicitly represent the tradeoff between accuracy and sparsity. GPLasso beats the state-of-the-art methods on both predictive performance and speed. Second, we propose network models based on matrix-variate Gaussian processes, which generalize the popular bilinear models to nonlinear factorization models in infinite feature spaces. Experiments on both synthetic and real-world networks demonstrate that our models have superior link prediction and community discovery performance. Last, we propose to generalize the matrix-variate Gaussian processes to tensors and apply them to nonlinear tensor factorization. Our nonlinear tensor factorization models—InfTucker—can be regarded as the classic Tucker decomposition in infinite feature spaces. In our experiments on chemometrics and social network datasets, our new models achieve significantly higher prediction accuracy than the state-of-the-art tensor decomposition approaches.^

]]> Feng Yan Computer Science http://docs.lib.purdue.edu/dissertations/AAI3556711 http://docs.lib.purdue.edu/dissertations/AAI3556711 Wed, 22 May 2013 15:53:08 PDT The purpose of this study was to determine the prevalence of pulmonary arterial hypertension in a population with connective tissue diseases, to describe demographics and clinical characteristics of patients with pulmonary arterial hypertension associated with connective tissue diseases, to determine patterns of pulmonary arterial hypertension-specific medication use in patients with pulmonary arterial hypertension associated with connective tissue diseases, and to compare health care utilization pre-initiation and post-initiation of sildenafil in patients with pulmonary arterial hypertension associated with connective tissue diseases. ^ An observational database analysis was conducted using a Commercial Claims database. One year-prevalence of PAH among individuals with connective tissue diseases was calculated by dividing the number of individuals with PAH in 2009 by the total number of individuals with connective tissue diseases. Prevalence of use of pulmonary arterial hypertension-specific medication was determined for each individual medication and for each therapeutic class. Medication persistence for pulmonary arterial hypertension-specific medications was calculated by counting number of continuous days on the first pulmonary arterial hypertension-specific medication therapy during twelve months after initiation of therapy. A zero inflated negative binomial model with random effects was used to compare days in hospital per month pre-initiation and post-initiation of sildenafil. ^ The estimated prevalence of pulmonary arterial hypertension in individuals with connective tissue diseases was 0.92 percent (CI: 0.86% to 0.98%) in this general population. The prevalence of pulmonary arterial hypertension-specific medication use was 24.1 percent (95% CI: 21.9% to 26.4%). The most frequently prescribed pulmonary arterial hypertension-specific therapeutic classes were the phosphodiesterase-5 inhibitors (14.8%) and endothelin receptor antagonists (14.7%). The most frequently prescribed pulmonary arterial hypertension-specific medications were sildenafil (14%) and bosentan (11.5%). When not using sildenafil, for one unit increase in month, the expected number of days in hospital increased by 2.8 percent. When using sildenafil, for one unit increase in month, the expected number of days in hospital decreased by 3.51 percent. ^ The prevalence of pulmonary arterial hypertension in persons with connective tissue diseases was higher than prevalence of idiopathic pulmonary arterial hypertension. The current finding adds epidemiological evidence to better understand pulmonary arterial hypertension in connective tissue diseases and underscores the need for monitoring for pulmonary arterial hypertension in patients with connective tissue disease. Only 24% of the studied population was taking pulmonary arterial hypertension-specific medications. Analysis showed some evidence that the most frequently used medication in that group, Sildenafil, may reduce hospital days within the time interval studied.^

]]> Xiaoqin Yang Health Sciences, Pharmacy http://docs.lib.purdue.edu/dissertations/AAI3556708 http://docs.lib.purdue.edu/dissertations/AAI3556708 Wed, 22 May 2013 15:53:07 PDT Accurate prediction of protein-ligand interactions and the associated binding affinity is a major task in computer aided drug design. It is crucial for the selection of potential lead and drug candidates. ^ Docking is an efficient molecular modeling method to predict the nativelike ligand binding mode and the corresponding binding affinity. To incorporate protein flexibility and dynamics into docking, a computationally efficient method that samples protein conformations when binding to structurally diverse ligands is highly demanded. We have developed a novel methodology, named 'Ligand model' concept (Limoc) to explore the receptor flexibility during docking simulation. In the ligand-model concept, short molecular-dynamics simulations are performed with a virtual ligand, represented by a collection of functional groups that binds to the protein and dynamically changes its shape and properties during the simulation. The ligand model essentially represents a large ensemble of different chemical species binding to the same target protein. We have demonstrated that Limoc yields significant improvements in predicting native-like binding poses and quantifying binding affinities compared to static docking and ensemble docking simulations into protein structures generated from long and computationally demanding MD simulation of apo receptor structure. ^ We utilized Limoc to generate ensembles of holo-like protein structures in combination with the relaxed complex scheme (RCS) to perform ligand virtual screening. We developed different schemes to reduce the size of the ensemble of protein structures to increase efficiency and enrichment quality. Utilizing experimental knowledge about a small set of actives for a target protein allows the reduction of the ensemble size to a minimum of three protein structures increasing enrichment quality and efficiency simultaneously. ^ An important factor contributing to the failure of docking to accurately predict binding affinities is the lack of inclusion of entropic information of the protein-ligand complex. We developed an efficient method to estimate configurational entropy of the bound ligand and interacting residues in the binding site. As part of the docking process, short Monte Carlo simulations of the ligand in a pre-generated ensemble of protein structures are combined with covariance matrix analysis to estimate the entropy of the bound ligand. A mixed scoring scheme dividing interacting residues into explicit and implicit residues allows for an efficient estimation of protein-ligand interactions. The entropy estimations of our method correlate quite well with the entropies derived from extensive MD simulations for each protein-ligand complex.^

]]> Mengang Xu Chemistry, Biochemistry|Health Sciences, Pharmacy|Biophysics, General http://docs.lib.purdue.edu/dissertations/AAI3556709 http://docs.lib.purdue.edu/dissertations/AAI3556709 Wed, 22 May 2013 15:53:07 PDT Wireless Sensor Networks (WSNs) have received considerable attention in recent years because of their numerous applications. Typically, a WSN consists of a large number of sensor nodes which can communicate with each other and with external base stations responsible for collecting the sensed data. In the sensor, a battery provides the essential power which is usually non-replenishable. As a result, the maximizing lifetime problem has driven most issues in research and practice concerning WSNs. Routing is an important means that enables to save energy and therefore prolong the lifetime. Another method that has been widely used to enhance the lifetime and achieve network scalability is data aggregation, which is known to be tightly coupled with routing topology. The research on routing combined with data aggregation in WSNs has previously uncovered new opportunities and challenges. ^ In this research we develop three routing protocols that incorporate the data aggregation, under the hierarchical routing topology. First, we propose a distributed cluster-based routing protocol: Predictive and Adaptive Routing Protocol using Energy Welfare (PARPEW). PARPEW applies the notion of Energy Welfare (EW) in choosing cluster heads whose role is to relay data from sensors to the base station, in an effort to achieve both energy efficiency and energy balance at the same time. Second, we further develop the PARPEW by devising an iterative mechanism that enables to identify better cluster heads. Third, we develop a tree-based routing protocol: Spanning Tree Of Residual Energy (STORE). STORE is flexibly applicable to scenarios that take into account (1) energy cost for data aggregation and (2) partial data aggregation, which are important considerations in WSNs that process multimedia data. Experimental results demonstrate that these protocols are capable of significantly prolonging the lifetime of WSNs over existing approaches under various scenarios.^

]]> Pu-Tai Ynag Engineering, Industrial http://docs.lib.purdue.edu/dissertations/AAI3556707 http://docs.lib.purdue.edu/dissertations/AAI3556707 Wed, 22 May 2013 15:53:06 PDT The ability to non-invasively characterize tissue microvascularity and microstructures in a large area can provide an invaluable tool in various preclinical and clinical applications. Tissue properties are often spatially heterogeneous in a large area. Conventional microscopic imaging techniques are, however, not adequate to visualize detailed field alterations due to a limited field of view. To overcome this fundamental limitation, we have developed a mesoscopic (i.e. between microscopic and macroscopic) spectroscopic imaging modality. We have conducted a series of biological studies to establish the utilization of our mesoscopic imaging modality for addressing critical biological and clinical problems. First, we have demonstrated that the combination of a back-directional (angular) gating configuration and multispectral measurements allows us to take advantage of intrinsic tissue properties, such as scattering anisotropy and hemoglobin absorption, and to achieve an enhanced imaging contrast, resolution, and depth. Second, to assess microvascular alterations as well as to provide new insights about field cancerization during early carcinogenesis, we have quantified spatial and temporal changes in dermal microvascular hemoglobin content in experimental skin carcinogenesis, including photocarcinogenesis. Spatial and temporal analysis of focal areas of inflammatory hyperemia can predict not only whether tumors will form, but also where they will form. We have also assessed effects of topical celecoxib treatment as a chemoprevention strategy. The chemopreventive activity of celecoxib correlates with its ability to suppress formation of hyperemic foci. Third, we have further applied our imaging approach to visualize spatial heterogeneity of tissue microstructural alterations at the scales of hundreds of nanometers in other biological tissues and biomaterials. We have demonstrated the feasibility of our imaging methods for surgical guidance and biomaterial characterization. Overall, the advantages of our imaging approaches are the large field of view for whole-field assessments, the use of endogenous tissue contrasts, the sensitivity to subtle alterations of intrinsic tissue properties, and the simplicity of the instrumentation. Thus, we envision that the newly-developed imaging methods will have the potential for broad utilization to characterize tissue properties in a variety of research and industrial settings.^

]]> Zhengbin Xu Engineering, Biomedical http://docs.lib.purdue.edu/dissertations/AAI3556705 http://docs.lib.purdue.edu/dissertations/AAI3556705 Wed, 22 May 2013 15:53:05 PDT Many domains exhibit natural relational structures—from the world wide web to scientific publications and social and biological systems. We call such domains single network domains, because the whole domain can be represented as a single network, where every data instance is potentially linked to some other instances. In such domains, the relational links between data instances often indicate probabilistic dependencies between the attribute values on the instances, which can be explored by machine learning algorithms to improve modeling and prediction accuracy. ^ Due to the existence of dependences, it is no longer suitable to assume data instances from a single network domain to be independent and identically distributed (IID). Moreover, statistical relational learning (SRL) methods for single networks often model the joint distribution over data instances, and therefore the models do not fit into the conventional paradigm of machine learning either. We argue that single network domains deserve more attention because classic theory is no longer applicable, and comparing with IID domains, there are a number of new factors that affect the performance of relational learning for single network domains. By disentangling these factors and formally analyzing SRL methods, there is a great opportunity to advance the state of the art. This thesis research has achieved the following goals as a preliminary attempt in the area: (1) establishing theoretical results regarding the learnability of relational models by formulating suitable assumptions on the weakness of infinite range dependence, (2) developing new relational learning and inference algorithms that improve classification performance, and are also scalable to large networks, and (3) developing novel relational model representations based on assumptions that are more suitable for real world networks.^

]]> Rongjing Xiang Statistics|Computer Science http://docs.lib.purdue.edu/dissertations/AAI3556706 http://docs.lib.purdue.edu/dissertations/AAI3556706 Wed, 22 May 2013 15:53:05 PDT Stratified flows with small density difference commonly exist in geophysical and engineering applications, which often involve interaction of turbulence and buoyancy effect. A combined particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) system is developed to measure the velocity and density fields in a dense jet discharged horizontally into a tank filled with light fluid. The refractive indices of both liquids are matched. The flow structures and mixing dynamics are studied by examining the averaged parameters, turbulent kinetic energy budget, as well as modeling of momentum flux and buoyancy flux. At downstream of the jet, profiles of velocity and density display strong asymmetry with respect to its center. This is attributed to the fact that stable stratification reduces mixing and unstable stratification enhances mixing. Experimental data also indicate that at downstream locations mixing length model performs better in mixing zone of stable-stratification regions, whereas in other regions eddy viscosity/diffusivity models with static model coefficients represent effectively momentum and buoyancy flux terms. The measured turbulent Prandtl number displays strong spatial variations in the stratified jet. ^ Quantifying the turbulent dissipation rate provides insights into the physics of the turbulent flows. However, the accuracy of estimating turbulent dissipation rate using velocity data measured by planar PIV is affected by the way of modeling the unresolved velocity gradient terms and the PIV spatial resolution. The synthetic PIV data are generated from a turbulence DNS dataset for validating the effectiveness of different methods. Direct estimate of turbulent dissipation rate from its definition using velocity gradients, with the assumption of isotropy, local axisymmetry, or local isotropy, shows significant decrease as interrogation window size increases. On the other hand, the indirect estimates of turbulent dissipation rate from energy spectra and structure function demonstrate less severe decrease as interrogation window size increases. We further propose two modified methods. The Modified Structure Function Method relies on an empirical relationship established by analyzing the synthetic PIV data. For a given measured value turbulent dissipation rate under a given interrogation window size, the true value can be determined from this relationship. The Modified Spectra Curvefit Method accounts the averaging effect introduced by the interrogation window in PIV processing algorithm and thus gives a better calculation of the energy spectra. When the new spectra data are used to curve fit the −5/3 slope, an improved estimate of turbulent dissipation rate is expected. Both modified methods are applied to experimental PIV data acquired from the turbulent jet experiment. They give nearly converged estimates of turbulent dissipation rate and Kolmogorov scale at different interrogation window sizes. ^ The measured velocity and scalar data are used to test Refined Similarity Hypotheses and its extension to passive scalar without adopting Taylor's hypothesis. In the previous studies, Taylor's hypothesis is widely applied to hot/cold wire data acquired in wind tunnels, and it is believed to introduce the artificial effect to the test results. In our study, the test results show that the stochastic variable υ is independent of r and &epsis; _r in the inertial subrange. Investigating P(υ: Re_r) strongly supports the statement that P(υ) is independent on Re_r when Re_r > 100. We also observe Re_r dependence of P(υ) when Re_r ∼ 1. For RSH-P, P(υ_&thetas;) depends on Re_r when r << L and is universal when Re_r >> 1. However, the independence of υ_&thetas; on r, &epsis;_r and χ _r is not fully supported by the present experimental results. (Abstract shortened by UMI.)^

]]> Duo Xu Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI3556702 http://docs.lib.purdue.edu/dissertations/AAI3556702 Wed, 22 May 2013 15:53:04 PDT Research on the barriers to self-management adherence in chronic care rarely addresses the learning and performance support patients need to improve their adherence to treatment and key activities. This correlational study investigated the relationships between patients' perceptions of barriers and adherence to key self-management activities, and the connection between patient demographics and barriers and adherence. ^ A survey containing questions of research interest was administered through Qualtrics to a sample of adults being diagnosed or at risk of chronic diseases draw from a local health care institution. Valid responses (n=420) entered into the data analyses. Fourteen items selected from chronic care and performance support were utilized as measures of barriers, and most of them were found significantly correlated with adherence. ^ A factor analysis was employed to thoroughly examine the dimensions of barriers and yielded three sub-scales of barriers: (1) Lack of performance support and poor communications, (2) Lack of capabilities, or physical and psychological obstacles accompanied by chronic conditions, and (3) Lack of time, motivation, and support from family. Regression models incorporated Factor (1) and (2), which accounted for a significant portion of variances in adherence to two key self-management activities. No significant correlation was observed between demographics and adherence, while some demographic items were associated with perceptions of barriers. Gender was the only demographic that showed significant difference in adherence to exercise. However, age, gender, education and income all played a role in the group differences in learning preferences. Findings from this study could further the understanding of barriers to adherence, help inform the design of chronic care education, align patients' needs and preferences with the selection of technologies and interventions, and eventually improve the design of learning and performance support interventions to self-management.^

]]> Xuemei Wu Education, Adult and Continuing|Education, Health|Education, Technology of http://docs.lib.purdue.edu/dissertations/AAI3556704 http://docs.lib.purdue.edu/dissertations/AAI3556704 Wed, 22 May 2013 15:53:04 PDT Photosynthesis is the only process of biological importance that can harvest the energy from the sun and produce carbohydrates for biomass formation. Even though photosynthesis processes are basic and critical to maize ( Zea mays L.) yield formation, direct measurements of photosynthesis in field-grown maize have been very rare. A three-year (2009 to 2011), two-site (West Lafayette and Wanatah, IN) field experiment with three plant densities (54,000, 79,000, and 104,000 plants ha^-1) and three nitrogen rates (0, 112 or 150, and 224 or 300 kg N ha^-1) were conducted with two commercial maize hybrids. Leaf photosynthesis, as well as whole-plant biomass per unit area, was measured at V10, V15, R1, R3 and R5 growth stages to directly examine photosynthesis changes over time and the complimentary relationships between source (at the fundamental photosynthesis level) and sink in explaining how plant density and N rate interacted to affect final yield outcomes. The objectives of the research were i) to determine the leaf photosynthesis response to plant density, and nitrogen stress at different growth stages, including both vegetative and reproductive growth, ii) to understand the relationship of leaf photosynthesis with leaf transpiration and with plant nitrogen status, iii) to determine the dependence of grain yield and yield components on photosynthesis levels at various growth stages, and iv) to identify the key factors for successfully measuring photosynthesis in field conditions. Mean air temperatures during the photosynthetic measurements narrowly ranged between 30°C and 38°C for all sampling occasions, and varied less than 4°C between reproductive stage measurements within a single site-year. Photosynthesis measurements were responsive to maize management system interactions at discrete vegetative and reproductive growth stages, and were meaningfully related to actual maize plant growth rates. High plant density significantly reduced leaf photosynthesis (A), transpiration ( E), stomatal conductance (g_s), SPAD value, as well as leaf N concentration, especially during reproductive stages. Nitrogen deficiency lowered leaf A, E, g_s, as well as leaf SPAD values and leaf N concentrations measured simultaneously. Leaf A and E were highly correlated, and with the same amount of transpiration increase, the increase of leaf photosynthesis was lower in high N rate treatment than in low N treatments. The intrinsic water use efficiency (WUEi) varied substantially among sampling times, but was unaffected by plant density or by N rate. Leaf photosynthetic rates declined faster with plant development, and responded more to plant density stress and N deficiency, than was apparent for SPAD values that were measured from the identical leaves used for photosynthesis measurements. SPAD values, therefore, were not a good indicator of photosynthetic rate. Strong correlations were observed of A with plant growth rate (PGR), A with per plant kernel weight (Kwp), A with per plant kernel number (Knp), and A with grain yield per unit area. Leaf photosynthesis was better correlated with PGR when the selected growth period was longer (more than 20 days) and the reproductive stage was included. In addition, correlations between leaf photosynthesis and PGR were higher when using the mean leaf photosynthetic rates for the beginning, middle (if applicable), and end of the growth period being examined. Maize grain yield tended to peak at the intermediate plant density, and increased in response to N rate in all six site years. Grain yield, Kwp, and Knp were more strongly correlated with leaf photosynthesis during reproductive stages rather than that of vegetative stages. Even though photosynthesis values represent instantaneous values from an individual leaf, they were meaningful indicators of maize plant response to management treatments. Our core photosynthesis measurement procedures were very effective in arriving at meaningful data, with minimal interference from non-treatment factors and plant-to-plant variation, by using a consistent time of daily measurement, controlled light intensity, multiple plants and consistent leaf sampling positions, and a specific isolation method just prior to measurement.^

]]> Yanbing Xia Agriculture, Agronomy|Agriculture, Plant Culture http://docs.lib.purdue.edu/dissertations/AAI3556701 http://docs.lib.purdue.edu/dissertations/AAI3556701 Wed, 22 May 2013 15:53:03 PDT The emergence of web-based scientific simulation portals has enabled scientists to quickly generate large complex scientific simulation data using high performance computing resources. The increasing complexity of these datasets has brought with it challenges of data exploration and analysis. An effective means of exploring scientific volumetric data is through direct volume rendering. Multi-dimensional transfer functions for direct volume rendering have been shown to be an effective means of extracting features and highlighting through the assignment of color and opacity. However, the complexity of setting volume rendering parameters can impede the users' ability to answer relevant scientific questions about their data. This is often due to the fact that designing a proper transfer function does not reflect the scientists' data analysis and exploration process. Furthermore, traditional transfer function widgets provide only limited information about the interaction and correlation of volumetric features since they only present the number of voxels in terms of feature magnitude. ^ This thesis presents an interactive information assisted data exporation and visualization framework for analyzing and exploring scientific simulation data. In this research, we design and develop data exploration and visualization techniques guided by additional information that is processed by analyzing local and global features within input datasets. Features obtained from internal data analysis are utilized to provide initial rendering parameter settings or additional information on top of the conventional user interfaces for data exploration. Our framework provides a semi-automated user interface for transfer function design, modification, and interaction utilizing line charts and contour lines within a slice view for enhancing local data features. We also present a novel abstract attribute space presentation detailing the relationship between the feature space and the volumetric space that leads to better data exploration. In multivariate data exploration, users are presented with a possible sequence for data exploration by employing our dimension ordering scheme and are able to perform logical operations on their selection of feature value ranges while exploring feature space by space. As an extension, our framework includes flow analysis for discrete events such as crime and healthcare reports that allows users to explore events and interactions over space and time to facilitate the discovery of patterns. Finally, we utilize modern GPU computation power and CPU clusters to support interactive data exploration for large datasets.^

]]> Insoo Woo Engineering, Computer http://docs.lib.purdue.edu/dissertations/AAI3556699 http://docs.lib.purdue.edu/dissertations/AAI3556699 Wed, 22 May 2013 15:53:02 PDT Compromised vascular perfusion is a major factor contributing to non-healing wounds and the progression of disease states such as ischemic heart disease and peripheral vascular disease due to inadequate blood flow throughout the damaged tissue region in vivo. It also becomes a problem in the design and success of engineered tissue constructs because of the lack of vascularization within the constructs. In both of these situations, the diffusion limitation of tissues has been exceeded and can only be remedied by creating a new vasculature with the ability to integrate with the host circulation and restore the blood flow to the affected area. This restoration can be achieved by recreating the process of vasculogenesis in which vessels are formed de novo undifferentiated endothelial precursor cell populations. Endothelial colony forming cells (ECFC) are promising therapeutic cells largely owing to their high proliferative capacity and ability to form vessel networks in vitro and in vivo. Combining ECFCs with a type I collagen-based delivery vehicle will allow for localization of ECFCs at the implantation site and guidance of ECFC vessel formation and stabilization. Type I collagen is an ideal biopolymer to serve as a 3D matrix for ECFCs because it determines in-vivo tissue form and function through its natural intermolecular cross-links and has a role in vascular development and maintaining vascular integrity. ^ We have developed an uncommon set of collagen building blocks that differ in intermolecular cross-link composition and can be used to create 3D collagen matrices that differ in their biophysical properties. Using collagen oligomers, two or more covalently cross-linked collagen monomers, we can independently control collagen fibril density and interfibril branching to specify matrix stiffness in the current study, to guide vessel morphogenesis. Other studies in the laboratory have also shown that oligomers can be used to control matrix permeability and diffusivity, as well as proteolytic degradation. Increasing the oligomer/monomer ratio, while maintaining a constant collagen concentration, results in an increase in interfibril branching and subsequently an increase in matrix stiffness upon in-vitro neutralization and polymerization. Overall, oligomers show increased interfibril branching over monomer under matched stiffness and concentration conditions. Using a new 3D morphometric analysis method in which we quantified the microstructure of lumen-containing ECFC vessel networks in monomer and oligomer matrices, we observed that stable, mature intermolecular cross-links and associated oligomers support more complex vessel networks with larger lumen diameters, vessel length, and total volume than monomers at the same concentration and matrix stiffness. These vessels, with lumen, persist beyond 7 days, unlike endothelial cells or endothelial precursors seeded within traditional monomeric matrices, and begin to undergo maturation and stabilizing through basement membrane deposition, which contributes to vessel persistence, without the addition of anti-apoptotic agents, phorbol esters, or accessory cells. ^ We propose that matrix-guided vasculogenesis is driven by a balance between ECM physical properties and cell traction forces and hypothesize that this balance is well established in oligomer matrices that are able to appropriately resist ECFC traction forces. To begin to explore and test this hypothesis, we focused on the role of the matrix-integrin-cytoskeletal signaling pathway in early- and late-stage vessel formation events to explain the mechanisms through which the cell-ECM force balance guides and regulates vessel morphogenesis. Using chemical perturbation of the actin cytoskeleton and focal adhesions and immunostaining of intra- and extracellular elements of the signaling pathway involved in vessel morphogenesis, we have observed qualitative differences in the ECFC response in vessel formation and the organization and expression of several elements. F-actin formation, β₁ integrin binding, and focal adhesion kinase (FAK) activation all appeared to increase with increased matrix interfibril branching or oligomer content. Furthermore, stimulation of the actin cytoskeleton promoted ECFC vessel formation in monomer more than oligomer, and matrix metalloproteinase activity (MMP) appeared to be up-regulated in oligomer, as well. These results, combined with our vessel microstructure findings provide additional evidence to support our theory that ECM biophysical properties are essential in regulating vessel morphogenesis through a cell-ECM force balance. ^ This work documents, for the first time, that intermolecular cross-links constitute a new and important design parameter and important determinant of the biophysical properties and vascular-instructive capacity of polymerizable collagen matrices to be used for cell culture, regenerative medicine, and engineered tissue applications.^

]]> Catherine Faye Whittington Biology, Cell|Engineering, Biomedical http://docs.lib.purdue.edu/dissertations/AAI3556700 http://docs.lib.purdue.edu/dissertations/AAI3556700 Wed, 22 May 2013 15:53:02 PDT This paper investigates changes in physician behavior given changes in procedures' profit margins. Unique methods are used to test for potential cross-substitution between procedures, and spillover effects by "upcoding" office visits. The observation-level Medicare data in the Carrier 2007 SAF was combined with the procedure specific cost data in the 2006 and 2009 Direct Practice Expense Inputs (DPEI) Summary Files to estimate whether two procedure's relative profitability affects the relative proportion that physicians perform them. A theoretical model is developed offering further insight into physician induced demand, and then components were estimated in an empirical analysis. Logit regressions estimate changes in direct utilization rates between mutually exclusive procedures. ^ During calendar year 2007, Medicare's physician reimbursements were flat for all procedures considered, so any change in a procedure's relative profitability must have come from changes in relative cost. The DPEI Summary Files for 2006 and 2009 provide data on some components of procedures' costs, and are used to identify changes in cost between the years 2005 and 2008. Since these years span 2007, then any cost changes following trends over this time period should affect the relative profitability of procedures over the year 2007. ^ Also a potential spillover from cost changes is examined. Physicians experiencing large cost changes across procedures in their practice may look for alternative means to make up for lost revenue, such as inflated billing for office visits. A physician's reimbursement for an office visit is directly tied to their self-reported effort level, so inflated reporting ("upcoding") could generate additional income.^

]]> Ross Alan Winegar Economics, General|Economics, Labor|Sociology, Public and Social Welfare|Health Sciences, Health Care Management http://docs.lib.purdue.edu/dissertations/AAI3556697 http://docs.lib.purdue.edu/dissertations/AAI3556697 Wed, 22 May 2013 15:53:01 PDT As a genre, American literary realism has historically taken a back seat to more critically attractive theoretical movements and organizational rubrics, such as Modernism and Postmodernism. Critiques like Amy Kaplan's Marxist indictment of class representations in the fiction of William Dean Howells have contributed to an overall contentment with the idea that realism had lost its significance in American literary culture. Other critics and historians, like Robert Rebein and Gordon Hutner, have argued that the revival of the short story and the minimalist movement in the eighties spurred a concurrent revival in realism. In fact, American realism never went away, and its quiet evolution has culminated in a form of contemporary realism that resists the dismissive critiques of earlier forms. America has continued to read realist novels throughout the last century and into this one, and the cultural impact of this practice needs to be acknowledged and examined. ^ In an effort to establish some parameters for the specific category of contemporary realism, I begin with an examination of Howells's arguments about the function and operation of realism at the beginning of the twentieth century. Realism must now respond to a more evolved readership, hence Howells's edict is even more imperative today—the realist novel must provide explorations of possible moral responses rather than limited didactic representations. Given the similarities between characters like Silas Lapham, George Babbitt, and Rabbit Angstrom, a pattern emerges of male characters being faced with their own moral shortcomings. Examining this pattern leads to an understanding of the cultural role and utility of the contemporary realist novel. Beginning with Updike's Rabbit, Run, each chapter undertakes a close reading of one or more novels. Particular attention is paid here to the ways in which masculine identity is constructed through capitalistic pressures, underscoring how specific social spaces operate in both the novel as a form and in the real world experiences of the reader. Subsequent chapters examine novels by Richard Ford, Phillip Roth and Chang-rae Lee, and finally, Joyce Carol Oates and Anne Tyler. The function and durability of contemporary realism is demonstrated through an examination of characters that exhibit particular difficulty in establishing acceptable or socially useful masculine identities. ^

]]> Martin J Whitehead Literature, American http://docs.lib.purdue.edu/dissertations/AAI3556698 http://docs.lib.purdue.edu/dissertations/AAI3556698 Wed, 22 May 2013 15:53:01 PDT Density Functional Resonance Theory (DFRT) is a complex-scaled version of ground-state Density Functional Theory (DFT) that allows one to calculate in-principle exact resonance energies and lifetimes. The energy and lifetime of the lowest-energy resonance of unbound systems is encoded into a complex "density'' obtained via complex-coordinate scaling. Two electron exactly-solvable models are used to test the theory before proceeding to a three-dimensional implementation which uses approximate functionals. DFRT subsumes ground-state DFT in that it can facilitate calculations for both bound and metastable states, and thus failures of current approximate DFT methods can be studied from a new perspective. Following this line of thinking, derivative discontinuities in the DFT energy functional, orbital energies, and numerical behavior are explored. Finally, a time-dependent version of DFRT is developed to treat high-lying resonances. An analog of the Runge-Gross theorem is established, and the first order complex density response is shown to contain poles at both bound and metastable excitations motivating an eigenvalue problem for calculating excitations.^

]]> Daniel L Whitenack Chemistry, Physical|Physics, General|Energy http://docs.lib.purdue.edu/dissertations/AAI3556695 http://docs.lib.purdue.edu/dissertations/AAI3556695 Wed, 22 May 2013 15:53:00 PDT The research contained in this thesis is presented in two related parts. The first part focuses mainly on method development for better detecting and quantifying interactions between flavonoids and ascorbic acid, especially in powdered forms exposed to differing levels of moisture. The second part describes an in depth study of the most important flavonoid-ascorbic acid interactions identified using the approaches developed in part one, namely anthocyanin-ascorbic acid interactions. ^ In part one, an integrated approach for determining the stability of flavonoids and ascorbic acid in powders was developed. A rapid analyte solubility procedure served to decide whether HPLC, GLC, or NMR would best serve to measure stability. Both the flavonoid under study and ascorbic acid were measured in one analysis with any of the determinative methods. Seventeen flavonoids of differing type and ascorbic acid were used to demonstrate the utility of the method. The approach was applied to monitor the effects of storage relative humidity on the stability of several flavonoid powders with and without ascorbic acid. Results showed that quercetin, luteolin, taxifolin, naringenin, and naringin were stable for as long as 8 weeks in RHs up to 98%, ascorbic acid was significantly destroyed in the presence of quercetin, taxifolin, and taxifolin at 98% RH. Both grape anthocyanins and ascorbic acid were unstable in the presence of each other at 98% RH. The approach developed and described in part one not only led to the further studies described in part two of this thesis, but also should be of value to other researchers working to better define the stability of flavonoids in food and supplement systems. ^ In part two, the stability of anthocyanins and ascorbic acid were further studied in detail for both solutions and powders. The stability of cyanidin 3-glucoside, highly purified and present in semi-purified extracts also containing cyanidin 3-(6"-malonoyl)glucoside, petunidin 3-glucoside, delphinidin 3-glucoside, delphinidin 3-(6"-acetoyl)glucoside, and/or delphinidin 3-(6"-coumaroyl)glucoside in combination with ascorbic acid was determined in solution at differing pH and temperature levels and dry powders at different relative humidity. Results generally confirmed the mutual destruction of anthocyanins and ascorbic acid in solution with increasing pH and temperature, however improved stability of acylated anthocyanins and those with differing flavylium cores was not observed. With powders, stability was related to increasing levels of moisture, but results did not necessarily parallel those recorded for liquids. Key assays included HPLC analyses of individual anthocyanins and ascorbic acid as well as CIELAB color measurements, including the generation of color swatches. The latter were found to be a very useful tool for evaluating and preserving results. The results of this research should further the efforts toward the use of anthocyanins as replacers for synthetic colorants, especially in those products likely to contain meaningful levels of ascorbic acid, such as powdered beverages.^

]]> Megan E West Agriculture, Food Science and Technology http://docs.lib.purdue.edu/dissertations/AAI3556696 http://docs.lib.purdue.edu/dissertations/AAI3556696 Wed, 22 May 2013 15:53:00 PDT To develop improved methods of transition prediction for isolated roughness, based on the growth of disturbances in the roughness wake, the underlying insta- bility mechanisms must first be characterized. A cylindrical roughness element was used to introduce instabilities into the laminar nozzle-wall boundary layer in the Boeing/AFOSR Mach-6 Quiet Tunnel at Purdue University. Instabilities were detected in the roughness wake using flush-mounted pressure sensors, at both near-effective and near-critical conditions. These are the first such instabilities measured at hypersonic speeds. ^ Experimentally-observed instabilities were compared to computations performed by others for a large roughness with a height of 1.2 times the boundary-layer thickness. Direct numerical simulations allowed a detailed analysis of the entire flow field, while experimental measurements discovered the real flow physics and confirmed the findings of the computations. For a large roughness height of 10.2 mm, the dominant mechanism for transition was identified. An instability with a frequency near 21 kHz was detected upstream of the roughness, as predicted by the computations, suggesting that the instability originates within the separation region. Unstable shear layers and horseshoe vortices appeared to cause transition downstream of the roughness for this case. As the roughness height was reduced, there appeared to be a change in the dominant instability mechanism. Several possible instabilities were identified for smaller, near-critical roughness heights that caused incipient transition on the nozzle wall.^

]]> Bradley M Wheaton Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI3556694 http://docs.lib.purdue.edu/dissertations/AAI3556694 Wed, 22 May 2013 15:52:59 PDT Means for effecting ion trap dipolar DC collision induced dissociation (DDC CID) on a quadrupole/time-of-flight in a mass spectrometer have been implemented for the broadband dissociation of a wide range of analyte ions. The DC dipolar-based fragmentation method provides an ion trap-based means for inducing fragmentation of ions in a large mass-to-charge range simultaneously. It can be effected within an ion storage step in a quadrupole collision cell that is operated as a linear ion trap or as ions are continuously transmitted through the collision cell. A dipolar DC potential is applied across one pair of rods in the quadruple collision cell of a QqTOF hybrid mass spectrometer to effect fragmentation. The application of dipolar DC (DDC) in the RF-only ion guide (Q0) of a hybrid quadrupole/time-of-flight (QqTOF) mass spectrometer for collision-induced declustering of large bio-ions is also described with DDC collisional activation (DDC CA) is employed in the trapping mode. Ions are collisionally cooled by Q0 trapping to prevent radial ion loss before and after DDC CA is applied. As a broadband technique, ion trap DDC CA can decluster a large mass-to-charge range simultaneously. ^ Gas-phase intra-molecular crosslinking of the protein ubiquitin cations has been demonstrated via ion/ion reactions with anions of homobifunctional N-hydroxysulfosuccinimide (sulfo-NHS) ester reagent. The ion/ion reaction between multiply-protonated ubiquitin or melittin and crosslinker monoanions produces a stable, charge reduced complex. Covalent crosslinking is indicated by the consecutive loss of two molecules of sulfo-NHS under ion trap collisional activation conditions. The presence of the covalent modification is verified by the presence of covalently crosslinked sequence ions produced by ion-trap collision-induced dissociation of the ion generated from the losses of sulfo-NHS. Analysis of the crosslinked sequence fragments allows for the localization of crosslinked primary amines, enabling proximity mapping of the gas-phase 3-D structures. The formation of gas-phase intermolecular covalent cross-links has been demonstrated via ion/ion reactions of mutually stored ions of opposing polarities. Specifically, dimers of ubiquitin and cytochrome C were cross-linked with the sulfo-NHS ester-based reagent sulfo-EGS. The sulfo-NHS losses from the dimers were isolated and subjected to additional ion trap CID. Both ubiquitin and cytochrome C homodimers gave CID product ions corresponding to sequence fragments of the monomer cross-linked to intact monomers, indicating that intermolecular crosslinking has taken place. Control of both proton transfer and complex forming ion/ion reaction rates has been demonstrated by applying dipolar DC in both the mutual storage and transmission modes.^

]]> Ian K Webb Chemistry, Analytical http://docs.lib.purdue.edu/dissertations/AAI3556691 http://docs.lib.purdue.edu/dissertations/AAI3556691 Wed, 22 May 2013 15:52:58 PDT In the first part of this thesis, we investigate the propagation of quantum fluctuations in a nonlinear interferometer comprising under conditions of harmonic generation by computer simulations. This investigation assumes idealized conditions such as lossless and uniform nonlinear media, an ideal cavity and ideal photodetectors. After linearizing wave equations for harmonic generation with a coherent state input, we obtain equations for one dimensional spatial propagation of the mean field and quantum fluctuations for initial conditions set by arbitrary interferometer phase. We discover that fluctuations are de-squeezed in the X and Y quadratures as the interferometer phase is tuned. However, we discover that there is are quadratures P-Q obtained by rotating the X-Y quadratures for which squeezing is improved byfactors of 10⁹. We present a practical idea to implement rotation of X quadrature fluctuations to the Q quadrature by using an ideal empty optical cavity. Signal-to-Noise ratio of the nonlinear interferometer was calculated and compared with thatof a linear interferometer with coherent state input. We calculated a maximum performance improvement of a factor of 60 for a normalized propagation length &zgr;₀ = 3 under ideal conditions. In the second part of this thesis, we investigate experimental arrangements to transfer atomic coherence from light to cesium atoms. We discuss the experimental arrangement to generate coherence under conditions of electromagnetically induced transparency (EIT). We measure a continuous wave EIT width of 7.18 MHz and present results for pulsed arrangements.^

]]> Prashant Srinivasan Physics, Quantum|Physics, General|Physics, Optics http://docs.lib.purdue.edu/dissertations/AAI3556693 http://docs.lib.purdue.edu/dissertations/AAI3556693 Wed, 22 May 2013 15:52:58 PDT The endothelium is a single layer of cells lining the arteries and is involved in many physiological reactions which are responsible for vascular tone. Free radicals are important participants in these chemical reactions in the endothelium. Here we quantify free radicals, ex vivo, in biological tissue with continuous wave electron paramagnetic resonance (EPR). In all of the experiments in this thesis, we use a novel EPR spin trapping technique that has been developed for tissue segments. EPR spin trapping is often considered the 'gold standard' in reactive oxygen species (ROS) detection because of its sensitivity and non-invasive nature. In all experiments, tissue was placed in physiological saline solution with 190-mM PBN (N-tert -butyl-&agr;-phenylnitrone), 10% by volume dimethyl-sulphoxide (DMSO) for cryopreservation, and incubated in the dark for between 30 minutes up to 2 hours at 37°C while gently being stirred. Tissue and supernatant were then loaded into a syringe and frozen at -80°C until EPR analysis. In our experiments, the EPR spectra were normalized with respect to tissue volume. ^ Conducting experiments at liquid nitrogen temperature leads to some experimental advantages. The freezing of the spin adducts renders them stable over a longer period, which allows ample time to analyze tissue samples for ROS. The dielectric constant of ice is greatly reduced over its liquid counterpart; this property of water enables larger sample volumes to be inserted into the EPR cavity without overloading it and leads to enhanced signal detection. Due to Maxwell-Boltzmann statistics, the population difference goes up as the temperature goes down, so this phenomenon enhances the signal intensity as well. ^ With the 'gold standard' assertion in mind, we investigated whether slicing tissue to assay ROS that is commonly used in fluorescence experiments will show more free radical generation than tissue of a similar volume that remains unsliced. Sliced tissue exhibited a 76% increase in ROS generation; this implies that higher ROS concentrations in sliced tissue indicate extraneous ROS generation not associated with the ROS stimulus of interest. ^ We also investigated the role of ROS in chronic flow overload (CFO). Elevation of shear stress that increases production of vascular ROS has not been well investigated. We hypothesize that CFO increases ROS production mediated in part by NADPH oxidase, which leads to endothelial dysfunction. ROS production increased threefold in response to CFO. The endothelium dependent vasorelaxation was compromised in the CFO group. Treatment with apocynin significantly reduced ROS production in the vessel wall, preserved endothelial function, and inhibited expressions of p22/p47phox and NOX2/NOX4. The present data implicate NADPH oxidase produced ROS and eNOS uncoupling in endothelial dysfunction at 1 wk of CFO. ^ In further work, a swine right ventricular hypertrophy (RVH) model induced by pulmonary artery (PA) banding was used to study right coronary artery (RCA) endothelial function and ROS level. Endothelial function was compromised in RCA of RVH as attributed to insufficient endothelial nitric oxide synthase cofactor tetrahydrobiopterin. In conclusion, stretch due to outward remodeling of RCA during RVH (at constant wall shear stress), similar to vessel stretch in hypertension, appears to induce ROS elevation, endothelial dysfunction, and an increase in basal tone. ^ Finally, although hypertension-induced vascular stiffness and dysfunction are well established in patients and animal models, we hypothesize that stretch or distension due to hypertension and outward expansion is the cause of endothelial dysfunction mediated by angiotensin II type 1 (AT1) receptor in coronary arteries. The expression and activation of AT1 receptor and the production of ROS were up regulated and endothelial function deteriorated in the RCA. The acute inhibition of AT1 receptor and NADPH oxidase partially restored the endothelial function. Stretch or distension activates the AT1 receptor which mediates ROS production; this collectively leads to endothelial dysfunction in coronary arteries.^

]]> Cynthia D Wassall Chemistry, Biochemistry|Physics, General|Biophysics, General http://docs.lib.purdue.edu/dissertations/AAI3556675 http://docs.lib.purdue.edu/dissertations/AAI3556675 Wed, 22 May 2013 15:52:57 PDT Mass spectrometry (MS) is a powerful tool for the analysis of biological samples. Different types of chemicals, such as therapeutic drugs, proteins, peptides, oligonucleotides, can be identified with high specificity and high sensitivity in a high-throughput manner. Sampling and ionization, the physical processes of converting the sample molecules into ions, is a key step for analyzing biological samples using mass spectrometry. The production of non-volatile intact ions using soft ionization techniques has significantly widened the scope of applying mass spectrometry in biological studies. Spray ionization is one of the most favorable soft ionization methods for biological sample analysis especially for biological macromolecules. However, conventional spray ionization methods suffer from the matrix effects. Salts and other contaminants in the samples can strongly inhibit the ionization efficiency of the targeting molecules, and sample extraction and separation are usually required before ionization and mass analysis are performed. The goal of the research is to develop and study new spray ionization methods to obtain the intact analyte ions from complex biological matrices without any sample preparation. Two problems need to be solved to achieve the goal: how to get intact ions with little fragmentations and how to overcome the matrix effects. Even though spray ionization techniques are generally regarded as soft ionization methods with little fragmentations produced, recently, a surprising phenomenon was found that under specific conditions, significant backbone fragmentation could be observed during nanoESI of peptides. Thus, it is interesting and helpful to study what factors are important to decide whether intact ions or fragmented ions will be produced during spray ionization. At the meantime, the conventional spray ionization methods are vulnerable to the matrix effects. Porous materials such as paper are proposed to be effective substrates for direct sampling and ionization of biological samples. By selecting the proper porous substrates and solvents, the extraction of targeting molecules is expected to be enhanced and the matrix effect could be reduced. Due to the simple setup and good sensitivity, the new ionization method, named as paper spray ionization, which could obtain the intact analyte ions directly from complex biological matrices, offers a great opportunity for point-of-care (POC) testing of biological samples using MS.^

]]> He Wang Chemistry, Analytical|Engineering, Biomedical http://docs.lib.purdue.edu/dissertations/AAI3556674 http://docs.lib.purdue.edu/dissertations/AAI3556674 Wed, 22 May 2013 15:52:57 PDT The proliferation of post-racial theory (PRT) in both social and political spheres of dominant American hegemony has illustrated a desire among academic circles to move past race and racial categories in social analysis. However, absent within post-racial rhetoric is critical language on how to abolish racism and racial inequality. (Samad 2009) It is my contention that the application of post-racial theory in social and legislative arenas will fail to eliminate many of the economic or curriculum based inequities within public school education. Furthermore, I contend that the aim of post-racial theory to deconstruct race as a tool for social analysis will exacerbate current achievement gaps and guarantee that equity in terms of school funding and quality of non-racist teacher instruction for non-white students may not be achieved or even addressed. Designed to combat and eliminate the relevance of attempts to demonize poor, urban, youth of color, are the Culture Affirming Charters (CAC's) and independent schools. The success of the CAC's represent the transformative potential of a truly post-racial mechanism as they are doing the critical work of bridging race-based academic achievement gaps by creating environments where non-Whites are educated as equal in culturally affirming environments. Research into the schools and the various applications of culture-affirming pedagogy within them should serve to broaden the post-race canon to include such mechanisms designed to counteract the effects of racism.^

]]> Christopher A Warren African American Studies|American Studies|Black Studies|Education, Sociology of http://docs.lib.purdue.edu/dissertations/AAI3556670 http://docs.lib.purdue.edu/dissertations/AAI3556670 Wed, 22 May 2013 15:52:56 PDT In this dissertation a general framework to extend the Stein's method and the Nourdin-Peccati analysis is proposed. An upper bound (NP bound) for distances (that induce a stronger topology than the convergence in law) is provided in this general framework for the Wiener and Wiener-Poisson spaces. Given a reference random variable (supposed to be either Multivariate Normal or a general square integrable real-valued random variable), it is studied the solution of its Stein's equation, obtaining universal bounds on its partial derivatives. Then is extended the analysis of Nourdin and Peccati by bounding, in the proposed general framework, well chosen distances. This is illustrated with the Multivariate Normal case (which was worked already by several authors) and then is studied deeply the one dimensional version of this general NP bound, including convergence to general distributions such as members of the Exponential and Pearson families. Using these results, is obtained non-central limit theorems, generalizing the ideas applied to their analysis of convergence to Normal random variables. This is done in both Wiener space and the more general Wiener-Poisson space. In the former, is studied conditions for convergence under several particular cases and characterize when two random variables have the same distribution. While in the latter space, is done an extension of some results already known in the Wiener space, such as the so-called "fourth moment theorem'' and the second order Poincaré inequality. Finally, will is shown several application to central and non-central limit theorems with relevant examples: linear functionals of Gaussian subordinated fields (where the subordinated field can be processes like fractional Brownian motion or the solution of the Ornstein-Uhlenbeck SDE driven by fractional Brownian motion), bilinear functionals of Gaussian subordinated fields where the underlying process is a fractional Brownian motion with Hurst parameter bigger than 1/2, Poisson functionals in the first Poisson chaos restricted to "small'' jumps (particularly fractional Lévy processes) and the product of two Ornstein-Uhlenbeck processes (one in the Wiener space and the other in the Poisson space).^

]]> Juan J Viquez Applied Mathematics|Theoretical Mathematics http://docs.lib.purdue.edu/dissertations/AAI3556664 http://docs.lib.purdue.edu/dissertations/AAI3556664 Wed, 22 May 2013 15:52:55 PDT Undergraduate science and engineering institutions are currently attempting to improve recruiting practices and to retain engineering majors by addressing what many studies document as the major challenges of poor instruction. Service is described as experimental learning through the integration of traditional classroom teaching with structured community service. Implementation of service-learning is a response to the paradigm change in education from a focus on teaching to a focus on learning. In the last twenty years, service-learning has received a great deal of attention at the postsecondary/ higher education and secondary education levels. Although a few disciplinebased service-learning programs are utilized in certain college science, engineering, and highschool curricula at institutions around the nation, there have been few qualitative studies conducted on the impact of discipline-based science and engineering service-learning. There has been no qualitative study that compares and contrasts disciplinebased science and engineering service-learning on high school and college science and engineering students.^

]]> Michael G Thompson Chemistry, General|Engineering, General|Education, Higher http://docs.lib.purdue.edu/dissertations/AAI3556668 http://docs.lib.purdue.edu/dissertations/AAI3556668 Wed, 22 May 2013 15:52:55 PDT North America's giant salamander, the eastern hellbender (Cryptobranchus alleganiensis alleganiensis) is a long-lived, obligately aquatic salamander. Thus, it is a model species for investigating the genetic architecture of lotic systems. However, many populations have experienced precipitous declines and are at risk for loss of genetic diversity and increased extinction. As a result, there is a need to assess population structure and genetic diversity across the riverscape to inform management efforts. My dissertation focuses on using molecular methods and population modeling to examine the conservation biology of this cryptic species. In chapter one, I assessed the genetic structure at the range-wide and landscape or drainage level (across stream hierarchical networks of basins, sub-basins, and stream reaches). I found relatively high levels of genetic diversity range-wide, indicating high quality genetic stock for conservation efforts. Across the geographic distribution, I found two genetically differentiated groups at the range-wide scale: 1) the Ohio River drainage and 2) the Tennessee River drainage. At the drainage scale, I found most of the genetic variation partitioned within streams. I also found a strong pattern of isolation by distance at the drainage scale. In chapter two, I used molecular markers as genetic tags to assess the retention of Passive Integrated Transponder tags for eastern hellbenders within the Blue River. This provided a method for validating estimates of population size based on previous mark-recapture studies for Indiana's sole remaining population of eastern hellbenders. Lastly, in chapter three, I developed a stage-structured life-history model for the Blue River to assess the efficacy of management strategies on population growth and long-term population viability. I found a high probability of complete extirpation unless management practices are implemented to ensure adult presence and increase early life-stage survival. Several management actions are recommended to stabilize population projections, including initiating a head-starting program and conducting female-biased translocations to facilitate population growth. When taken together, this research provides a framework to inform wildlife management strategies and further our understanding of the conservation genetics and population dynamics of this cryptic salamander species.^

]]> Shem D Unger Agriculture, Wildlife Conservation|Biology, Ecology|Biology, Genetics http://docs.lib.purdue.edu/dissertations/AAI3556663 http://docs.lib.purdue.edu/dissertations/AAI3556663 Wed, 22 May 2013 15:52:54 PDT Alternative energy sources are needed to respond to the continued increase in the global energy needs and a potential decrease in the future supplies of fossil fuels. Solar hydrogen conversion in which sunlight is harnessed to split water into H₂ fuel and O₂ is a promising source of energy because it is renewable and produces no CO₂. A number of semiconducting oxide materials have shown promise for overall water splitting for the generation of hydrogen over the years. In this work we focus on the synthesis and analysis of undoped and C-doped cadmium indate (CdIn₂O ₄) thin films and nanoparticle powders, and their evaluation for hydrogen evolution via water splitting. The catalyst was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis, scanning electron microscopy (SEM), and BET surface adsorption measurements. Spray and sol-gel pyrolysis methods were used for the synthesis of the materials. Doping C into CdIn ₂O₄ leads to enhancement in light absorption and the band gap was determined to be 2.3 eV in the nanoparticle powders. Carbon doping improves the photocurrent density by 33% and the H₂ evolution rate by a factor of two. The performance of C-doped CdIn₂O₄ were optimized with respect to several synthetic parameters, including the In:Cd molar ratio and glucose concentration, calcination temperature, and the film thickness while the nanoparticles were additionally optimized to F127 concentration and platinum cocatalyst loading. ^ Hydrogen generation activity was evaluated under UV-visible irradiation without the use of a sacrificial reagent and using bandpass filters the quantum efficiency was determined. Compared to platinized TiO₂ in methanol C-CdIn₂O₄ showed a 4-fold increase in hydrogen production. The material was capable of hydrogen generation using visible light only and with good efficiency even at 510 nm. Using natural sunlight illumination, the material evolved hydrogen at a rate of 17 µmol h^-1. These studies show carbon-doped cadmium indate to be a promising catalyst for solar hydrogen conversion.^

]]> Jason M Thornton Alternative Energy|Chemistry, General|Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI3556660 http://docs.lib.purdue.edu/dissertations/AAI3556660 Wed, 22 May 2013 15:52:53 PDT Previous research shows that American learners of Japanese (AJs) tend to differ from native Japanese speakers in their compliment responses (CRs). Yokota (1986) and Shimizu (2009) have reported that AJs tend to respond more negatively than native Japanese speakers. It has also been reported that AJs' CRs tend to lack the use of avoidance or deflection (Yokota, 1986; Saito & Beecken, 1997; Shimizu, 2009). Since no evidence of pragmatic transfer has been reported, it is likely that AJs attempt to conform to the target language (TL). Yet, their attempt often results in deviance. There is a need therefore to investigate the reasons why learners do not always succeed in conforming to the TL norms. This study compares the CRs of the following informant groups: American learners of Japanese (AJs), native Japanese speakers (JJs), and American native English speakers (AEs). It attempts to examine the informants' rationales behind their CRs, which is done through a written discourse completion task (WDCT) format accompanying rank order questions designed to tap into the informants' reasoning. ^ Five types of situations are considered in the WDCT. Two of these have a complimenter of higher status who has expertise in the aspect complimented, while the other two situations involve a compliment addressed to the respondent's parents. In the last situation, informants were asked to respond to an undeserved compliment, such as a situation in which the respondent is complimented on his or her command of the native language due to the complimenter's misunderstanding. Through a comparison of the three informant groups' CRs and their rationales for their CRs, the current study attempts to identify the cause of the disparities between L2 (second or foreign language) learners and TL speakers. Thus, the findings of the present study will raise language instructors' awareness of how and why L2 learners' CRs tend to differ from those of TL speakers. Moreover, this study will offer suggestions for the reevaluation of classroom instruction. ^

]]> Naofumi Tatsumi Language, Linguistics|Sociology, Sociolinguistics http://docs.lib.purdue.edu/dissertations/AAI3556662 http://docs.lib.purdue.edu/dissertations/AAI3556662 Wed, 22 May 2013 15:52:53 PDT Gonadal soma-derived factor (Gsdf) is a transforming growth factor-beta (TGF-β)-related peptide that is found in fish and has been shown to promote the growth of primordial germ cells (PGCs) and spermatogonia in rainbow trout. To examine the biological function of Gsdf in zebrafish, I studied the expression pattern and biological activity of Gsdf in embryos and adult fish. Temporal expression analysis by RT-PCR revealed that gsdf transcripts were first detected at 1dpf and the level remained stable through 15dpf. Analysis of gonads by in-situ hybridization in wild type zebrafish showed that gsdf was predominantly expressed in granulosa cells surrounding early stage oocytes and Sertoli cells of adult testis. Inhibition of Gsdf translation by an antisense morpholino suppressed PGC number in the embryo while introduction of gsdf mRNA resulted in an increased number of germ cells. Cell culture studies revealed for the first time that recombinant zebrafish Gsdf promoted the proliferation of zebrafish ovarian germ cells (OGCs) in vitro and enhanced the expression of the germ cell markers nanos3 and dnd. The recombinant Gsdf activated a MAPK/ERK signaling pathway to control ovarian germ cell (OGC) proliferation and upregulates nanos3 expression. These results demonstrate that Gsdf plays a significant role in PGC development and OGC proliferation. To further investigate Gsdf function, I generated a zebrafish transgenic line, Tg(gsdf:neo-gsdf), in which the expression of a neomycin-resistant gene (neo) is driven by the gsdf promoter, and the 3'UTR. Immunohistochemistry analysis of this transgenic line revealed that the expression of the neomycin gene is detected in the granulosa cells that surround early-stage oocytes and Sertoli cells of adult testis. The use of this transgenic line made it possible to isolate homogenous populations of cells that express Gsdf from a four month old testis and ovary by G-418 selection. Use of the drug selected, Gsdf-expressing cells as a feeder layer for cell culture experiments resulted in significantly greater proliferation of spermatogonial and OGCs and enhanced expression of the germ cell markers, vasa and dnd. Use of this transgenic feeder cell line was an important step in optimizing the conditions required for establishment of long-term germ cell cultures. The OGC and spermatogonial cell cultures resulting from this work will provide an in vitro system for studies of testicular and ovarian germ cell biology.^

]]> Abraham Fisseha Tesfamichael Biology, Genetics|Biology, Cell|Health Sciences, Human Development http://docs.lib.purdue.edu/dissertations/AAI3556658 http://docs.lib.purdue.edu/dissertations/AAI3556658 Wed, 22 May 2013 15:52:52 PDT Chemically grown semiconducting nanowire is a promising candidate for future electronics since this bottom-up approach produces smooth nanowires with nanometer-scale control. However, most of the nanowire devices and circuits have been made from randomly positioned wires and are not suitable for large-scale integration, which requires precise control of the position and orientation of each nanowire. One solution is the controlled growth of horizontal nanowire arrays which allows large scale integration and simple electrical contacting scheme. However, previous efforts in growing horizontal nanowires included out-of-plane growth and lacked precise position control. ^ This thesis presents the fabrication of gold dot arrays on shallow, atomically smooth sidewalls, controlled growth of epitaxial silicon nanowires which have the direction orthogonal to the sidewalls and electrical contacting schemes of these nanowires to form field effect transistors. Our approach, which is suitable for large scale integration of nanowires, is distinct from other research in that it simultaneously meets three requirements: horizontal growth, controlled position and orientation, and growth on an insulator. Silicon nanowire was chosen in this work and practically, the result from this work can be expanded to other high carrier mobility material nanowires. In addition, the advantage of precise control of the position and orientation of each horizontal nanowire makes it possible to realize CMOS circuits with both PMOS and NMOS devices on neighboring nanowires, which has not been realized with randomly positioned nanowires that allow only one or the other.^

]]> Chookiat Tansarawiput Engineering, Electronics and Electrical|Nanotechnology|Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI3556656 http://docs.lib.purdue.edu/dissertations/AAI3556656 Wed, 22 May 2013 15:52:51 PDT The Center for Authentic Science Practice in Education (CASPiE) is a National Science Foundation funded initiative that seeks to introduce first- and second-year undergraduate students to research in their mainstream laboratory courses. To investigate the effects of this research-based curriculum, a longitudinal study was initiated at Purdue University (PU) and University of Illinois-Chicago (UIC), where CASPiE was implemented in a portion of laboratory sections of a general chemistry course (CHEM 116 at PU/CHEM 114 at UIC). The study examined the long-term effects of the CASPiE program on students' chemistry course performance, research involvement, and retention in STEM majors and future careers. ^ The results of the academic records analyses showed that PU CASPiE students from the opt-in semesters, i.e. those when students chose to enroll in the CASPiE sections, were higher-achieving students from the beginning of their college years and performed significantly higher than the students in the traditional sections. There were no significant differences in chemistry course performance among PU students from the randomly assigned semester. However, looking from the first semester chemistry course to the upper 300 level chemistry courses, randomly assigned PU students from the traditional sections had a significant performance decrease. The CASPiE students had a performance decrease that was not significant. At UIC, there were no significant differences between CASPiE and traditional students' chemistry performance. ^ Analyses of the academic records also revealed that there were no differences in STEM major retention between CASPiE and traditional students, from both PU and UIC. However, CASPiE students from UIC and the ones from the opt-in sections at PU graduated faster in average than traditional students. Students' responses to an online survey showed that there were no differences in students' choice of future plans in STEM or non-STEM fields (such as graduate or professional school, or type of job). ^ Interviews with PU's CASPiE and traditional students revealed that CASPiE students thought their laboratory work was applicable and relevant to other research and their lives and they tended to remember their lab activities more than the traditional students. CASPiE students thought the lab work they did was rewarding and they felt a sense of accomplishment. CASPiE students from the randomly assigned semester thought the experience was rewarding in retrospect, which is an important finding because during that semester students were frustrated that they were not able to choose their participation in CASPiE. Traditional students thought their lab experience helped prepare them for future courses at PU, whereas CASPiE students thought they were better prepared for class and lab in general, they learned how to keep a research notebook and write scientific papers, and that overall they learned how to conduct research. Specifically, CASPiE students thought they were able to use creativity in their lab. Both students from CASPiE and traditional sections thought they learned how to work well in groups through their lab experiences. ^ Based on the results, we can conclude that CASPiE was successful at providing first- and second-year students with research experiences in their second-semester general chemistry class, without negatively affecting their chemistry course performance, retention in STEM majors or future plans. PU CASPiE students from the opt-in years were higher-achieving students than the traditional counterparts therefore the significant differences in chemistry performance between these students are not surprising. The CASPiE curriculum did seem to have had an enhancing effect on the randomly assigned PU CASPiE students' chemistry performance over the years. Furthermore, CASPiE students from PU reported gains from doing research experiences that have previously been reported in the literature on undergraduate research experiences. The results from this study show that CASPiE could be a beneficial curriculum for STEM college educators who wish to have more students practice research during their college courses. (Abstract shortened by UMI.)^

]]> Gabriela A Szteinberg Chemistry, General|Education, Sciences http://docs.lib.purdue.edu/dissertations/AAI3556657 http://docs.lib.purdue.edu/dissertations/AAI3556657 Wed, 22 May 2013 15:52:51 PDT This study concentrates on characterization of the surface microstructure evolution in pure copper after severe plastic deformation in the form of "wave" sliding. This deformation process is based on conventional machining with modifications in the deformation geometry which leads to a drastic change in the output. Instead of the formation of a severely deformed chip, all the deformation goes into the workpiece, forming a severely deformed region in the workpiece subsurface. The amount of strain imposed into the subsurface of the material depends on the tool rake angle and the strain rate depends on the tool speed. In the present work, this deformation method is used to study the evolution of surface microstructure with strain and strain rate, and also the development of subsurface microstructure with depth from the surface. Three rake angles of -60°, -70° and -80° and two speeds of 1 and 200 mm/s were used in "wave" sliding, and two rake angles of 0 and +50° and speed of 10 mm/s were used in machining (chip formation) to study the surface microstructure evolution. ^ Surface and subsurface microstructures of the deformed specimens were characterized with a range of techniques including specimen preparation and imaging in the Focused Ion Beam/Scanning Electron Microscope (FIB/SEM), Transmission Electron Microscopy (TEM), Electron Backscatter Diffraction (EBSD) and Vickers microhardness. Microstructural characteristics addressed in this dissertation involve boundary spacing and misorientation of the dislocation structures formed after the deformation. Texture evolution was also addressed. ^ It was shown that the material flow during "wave" sliding at -70° and -80° rake angle was laminar while at -60° was rotational; which resulted in subsurface homogeneous (∼1) at -70°, (∼0.5) at -80° degree and heterogeneous (∼2-3.5) at -60° effective strain distributions, respectively. It was also shown that simple shear was the main deformation mode in "wave" sliding. Deformation textures developed in machining and "wave" sliding were proven to be of simple shear type and similar those developed in torsion and ECAP. The microstructures and textures developed at the surface of a chip rake face and corresponding machined surface were similar reflecting that the same effective strain was imposed in both surfaces. It was observed that in "wave" sliding, the material strain-hardened to a larger depth with one pass at a more positive rake angle, and with each pass (1-8) at -70° rake angle. Subsurface microstructure reached steady state after four passes in -70° "wave" sliding. It was confirmed that high speed (strain rate) "wave" sliding at -80° rake angle did not result in the formation of deformation twins.^

]]> Sergey Suslov Engineering, General|Nanotechnology http://docs.lib.purdue.edu/dissertations/AAI3556655 http://docs.lib.purdue.edu/dissertations/AAI3556655 Wed, 22 May 2013 15:52:50 PDT This qualitative study examines the cell phone policies of Indiana high schools. The study is based on the interviews of five Indiana high school principals. Of the five high school principals that were interviewed; four were male and one was female. In addition, two were principals completing their first year in their respective positions, whereas two others had ten or more years of experience in their position. All of the schools enrolled less than 1,500 students. An additional interesting fact is that four out of the five schools had a one-to-one computer initiative, where each student has a computer device provided by the school. ^ The methodology used in this exploratory study was Phenomenology. Phenomenology is utilized when the research requires a thorough examination of the experience that has been lived. The findings of the study will be reported in a narrative fashion. The analytical framework for this study is grounded theory. This framework was utilized after analyzing the data and concluding that it fits the findings of the study. ^ As a result of the study, six themes emerged. The overarching theme under which all others fell were that of personal experiences. Under the theme of personal relationships were the sub-assertions of safety and disruptions, disciplinary consequences, appropriate student cell phone use, stakeholders, and cyberbullying / sexting. In all areas discussed, the focus was on how the principals' personal experiences impacted the sub-assertion. ^ Each interview participant had numerous narratives about things that had happened with the cell phone policy, which either maintained their belief or changed it in some way. The concept of life experience cannot be overlooked when examining how cell phone policies were shaped, implemented, and enforced by the high school principals. In addition, the life experiences that the principals possessed were likely reactionary several years ago when cell phones first started to appear in school. While cell phones have changed through time, so have the principal's perceptions. It is now seen that the life experiences of principals influences policy, but that experience is utilized in an effort to be proactive to potential cell phone issues. ^ Overall, it appeared as though the principals were battling themselves over the educational uses of cell phones versus the potential dangers of implementing them in schools. The principals interviewed referred to positives and negatives of student cell phone use. Ultimately, the end result appeared to be policy implemented out of fear of misuse, versus acceptance of educational advantages. ^

]]> Theodore Stevens Education, Leadership|Education, Policy http://docs.lib.purdue.edu/dissertations/AAI3556654 http://docs.lib.purdue.edu/dissertations/AAI3556654 Wed, 22 May 2013 15:52:50 PDT Despite significant advances in better treating and managing prostate cancer, challenges remain in understanding and developing treatments for recurrent onset of the disease. One possible mechanism, involving the pathway to recurrence, is the transdifferentiation process, by which prostate cancers differentiate into neuroendocrine-like cells, also known as neuroendocrine differentiation (NED). NED has been associated with progression of prostate cancer, androgen-independent growth and poor prognosis. We previously reported that fractionated ionizing radiation (IR) induces NED. Dedifferentiation of these neuroendocrine-like cells gives rise to a population that has become resistant to chemotherapeutic agents and further IR induced cell death. In addition, we found that IR induced NED is associated with increased CREB phosphorylation. To examine the role of CREB in IR-induced NED, two approaches were utilized. A lentiviral short-hairpin (shRNA) approach was utilized to create tetracycline-inducible stable cell lines knocking down CREB and a separate tetracycline-inducible expression system was utilized to express a dominant negative CREB named acidic CREB, or ACREB. We found that knockdown of CREB in LNCaP cells decreased IR-induced neurite extension and expression of NSE after a 40 Gy cumulative dose. Likewise, expression of ACREB increased sensitivity to IR after a fractionated dose of 10 Gy. Additionally, we observed that IR treatment of LNCaP cells can be broken down into two unique phases. The first phase occurs during the initial two weeks of fractionated IR treatment and is associated with the acquisition of radioresistance. Only those cells able to acquire radioresistance progress to the next phase involving the acquisition of NED. Interestingly, knockdown of CREB was sufficient to inhibit IR-induced neurite extension, but did not have an apparent effect on IR-induced cell death during the first two weeks. On the other hand, expression of ACREB, which can bind all CREB/ATF1 family transcription factors and almost completely knockdown CREB expression, sensitized 34% of cells to IR during the first week. Taken together, we provide evidence that targeting CREB signaling, by inhibiting both the radioresistance and NED phases, is an attractive strategy for prostate cancer radiotherapy.^

]]> Christopher Suarez Biology, Molecular|Chemistry, Biochemistry|Health Sciences, Oncology http://docs.lib.purdue.edu/dissertations/AAI3556653 http://docs.lib.purdue.edu/dissertations/AAI3556653 Wed, 22 May 2013 15:52:49 PDT The springtime episodic depletion of tropospheric ozone and gaseous elemental mercury in the Arctic has been a focus of intense research over recent years. It has been generally accepted that bromine is the primary driver of Arctic ozone depletion events (ODEs) through a photochemical reaction mechanism catalyzed by Br atoms. Due to the very close correlation between ODEs and atmospheric mercury depletion events (AMDEs) it has been proposed that reactive bromine species (i.e., Br and/or BrO) are the dominant reaction partners for gaseous elemental mercury. The source of the reactive bromine to the Arctic boundary layer is believed to be the saline snow and ice surfaces that are ubiquitous in the Arctic marine environment, however, the specific source and production mechanism of these species remain unknown. Ground-based and satellite observations of BrO in the Arctic have confirmed the presence of reactive bromine chemistry during polar spring. However, there remains significant debate regarding the importance of reactive chlorine on ODEs and AMDEs, as well as on the impact of chlorine on important tropospheric chemical cycles. This gap in our understanding of Arctic chemistry is due in part to a lack of analytical techniques suitable for detecting the very low concentrations of ClO radical species present in the Arctic boundary layer. ^ This work describes a new method developed for the in-situ chemical detection of BrO and ClO radicals in ambient Arctic air using a dynamic chemical reaction system coupled to a gas chromatograph with electron capture detection. This method was used during the Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) 2009 field campaign in Barrow, Alaska for the detection and quantification of ClO radicals. This data, along with the suite of measurements from the OASIS study, was used to analyze the role of reactive chlorine in ODEs and AMDEs by both kinetic analysis and computer model simulations. Additionally, modeling studies were performed to investigate the interactions of the bromine, chlorine, and iodine radical species during ozone depletion periods. Finally, this work discusses the development and testing of a mobile, sled-based version of the chemical reaction method for determining halogen levels directly over the sea ice in an effort to gain a better understanding of the sources of halogen species to the Arctic polar boundary layer.^

]]> Chelsea R Stephens Atmospheric Chemistry|Chemistry, Analytical|Atmospheric Sciences http://docs.lib.purdue.edu/dissertations/AAI3556651 http://docs.lib.purdue.edu/dissertations/AAI3556651 Wed, 22 May 2013 15:52:48 PDT The field of microwave photonics (MWP), where the wideband and low-loss capability in optics is utilized to enhance the performance of radio frequency (RF) systems, has been significantly explored over the last decades. This perspective offers benefits that are unattainable with conventional electronics solutions, such as ultra-broad bandwidth, insensitivity to electromagnetic interference, transport through optical fiber networks, easy tuning control, or programmability. One important application of microwave photonics is the implementation of microwave filters for high carrier frequency and wide bandwidth RF waveform. In this thesis, MWP filters based on an optical frequency combs (OFCs) and a dispersive medium are presented. First, noise evaluation of MWP filters based on OFCs is explored to show the potential of optical frequency comb technology to operate over large distances in MWP filter links. Then, amplitude and phase control complex coefficient taps MWP filters are presented. We demonstrate reconfigurable and tunable flat-top MWP filters by applying positive and negative weights across the comb lines and adding a phase ramp onto the tap weights. Furthermore the application of this technique to phase filtering operation over an ultra-wide bandwidth will be demonstrated through high-speed real-time measurement. We present the implementation of matched filter to compress the chirped pulses to their bandwidth limited duration. We also explore the group delay ripple (GDR) compensation of chirped fiber Bragg grating (CFBG) which would reduce the delay of MWP filter links.^

]]> Minhyup Song Engineering, General|Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI3556650 http://docs.lib.purdue.edu/dissertations/AAI3556650 Wed, 22 May 2013 15:52:48 PDT Alphaviruses are small, spherical, enveloped positive-sense single stranded RNA viruses responsible for considerable human and animal disease. Alphaviruses form particles of 65-70 nm in diameter, and the icosahedral structures of many alphaviruses have been defined to very high resolutions by cryo-electron microscopy and crystallographic studies, revealing details of the interactions between the structural proteins required for assembly and budding. Nevertheless, much remains to be elucidated with respect to (nucleocapsid) NC assembly, structural protein interactions and trafficking, and the budding process. This disertation contains three distinct studies which, collectively, provide novel insights in the alphavirus assembly pathway. ^ In the first study, I have developed a system to introduce viral NC into live, mammalian cells, using microinjection as a platform, and incorporate these NC into viable virus-like particles (VLPs). Of particular interest is the fact that we can utilize, for the first time, NC assembled in vitro with non-RNA assembly substrates, and incorporate them into such VLPs. Using this system, further studies will examine the viral and host factors involved in transit of and envelopment of NC within an infected cell. Given previously published data detailing the ability to alter alphavirus tropism, our system may allow exploitation of the alphaviruses as a cell-type specific, targeted delivery tool for drugs and nucleic acids. ^ The second study detailed in this thesis involves classical structure-guided mutagenesis. Specifically, a 7Å cryo-EM based reconstruction of the type member of the alphavirus genus, Sindbis (SINV), was recently generated in our lab. Fitting the previously determined crystal structure of the SINV Cp protein ( Cp) into the density map revealed that residue R395 of the cytoplasmic domain of the E2 envelope protein (cdE2) and K252 of the Cp form a putative salt bridge in the virion. Furthermore, a 5-residue flexible loop containing residues K250 and K252 of the Cp was shifted away from cdE2 in the 7Å reconstruction relative to its expected position based on the Cp crystal structure. Given this data, I made multiple amino acid substitutions of K250 and K252 in the SINV Cp and explored the resulting phenotypes. In the context of full length virus, replacing K250 and K252 with negatively charged residues (either D or E) resulted in a lack of virus release as well the absence of NC formation in infected mammalian cells. Surprisingly, however, expressing the same Cp mutants in the mammalian cell without the envelope proteins (in a replicon-based system), or expressing/purifying the mutants from an E. coli expression system and assembling in vitro, yielded NC assembly in all cases. In addition, second-site mutations within cdE2, in the Cp K250/K252 mutant background, restored NC assembly in full-length virus, but not release of infectious particles. Taken together, our data suggests¸ for the first time, a role for the envelope proteins, namely cdE2, in the assembly of SINV NCs during infection in mammalian cells. ^ Finally, we explored the role of a newly described alphavirus structural protein that may be important during virus assembly. Alphavirus dogma has long dictated the production of a discrete set of structural proteins during infection of a cell: Cp, pE2, 6K, and E1. However, ribosomal frameshifting, occurring during translation of the alphavirus structural polyprotein, has been proposed to yield production of a novel protein, termed transframe (TF), comprised of a C-terminal extension of the 6K protein in the -1 open reading frame (ORF) (Firth et al., 2008). We identified TF in purified preparations of both SINV and Chikungunya (CHIKV) virus particles using a mass spectrometry-based approach. We constructed a panel of SINV mutants that alters the production, size, or sequence of TF, and demonstrate that TF is not absolutely required in culture, although disrupting TF synthesis leads to a decrease in virus release in mammalian and insect cell cultures. In a mouse neuropathogenesis model, animals infected with the TF mutants were protected from mortality unlike the wild type. Using a variety of additional assays, we demonstrated that TF retains ion-channel activity a la 6K, and lack of production of TF does not affect genome synthesis, particle infectivity, or transit of envelope proteins to the cell surface. However, EM analyses demonstrated an altered organization of virus induced membrane structures in the infected cell when TF was not produced. Thus, our data suggest that TF may be involved in virus particle assembly or release via generation of virus-induced cytopathic vacuoles. To attempt to elucidate a potential mechanism for the alteration in membrane rearrangement upon TF synthesis, we interrogated intracellular Ca²⁺ levels given that perturbation of ER calcium stores can lead to vesiculation of the cellular ER and that TF appears involved in virus-induced vesicle formation. Indeed, a TF knockout mutant demonstrated statistically significant lower [Ca²⁺]_i than the wild type in mammalian and insect cells.^

]]> Jonathan E Snyder Biology, General|Biology, Virology http://docs.lib.purdue.edu/dissertations/AAI3556649 http://docs.lib.purdue.edu/dissertations/AAI3556649 Wed, 22 May 2013 15:52:47 PDT Cochlear implants (CIs) can be utilized in profoundly deaf individuals to restore some sensation of hearing. Individuals who undergo surgery to receive a cochlear implant must subsequently adapt to an input neural signal that is distorted and acoustically underspecified. In general, performance is not restored to those levels achieved prior to the onset of deafness, especially cases of speech recognition in background noise. The goal of this thesis is to improve our knowledge of the auditory system, producing information that can be used to optimize cochlear implants for clinical benefit. ^ A portable real-time speech processor that implements an acoustic simulation model of a CI was developed for the iPhone to examine the nature of perceptual learning by assessing how speech intelligibility improves after training. Participants' underwent fMRI before and after exposure to the processor, measuring changes in neural activation following perceptual learning under real-time CI simulation. ^ A second project modeled the time-varying, frequency, and level dependent feedback of the medial olivocochlear reflex (MOCR), which is known to be important for speech recognition in noise. This system was implemented within the framework of a well-established computational model for normal and impaired hearing auditory nerve responses based on physiological evidence. The developed auditory nerve model is the first of its kind to be binaural, and includes feedback for both the crossed and uncrossed ipsilateral and contralateral pathways. Applications of this model, which include the efferent feedback loop, may contribute to our understanding of sensorineural hearing loss in noisy situations for hearing-impaired listeners.^

]]> Christopher J Smalt Biology, Neuroscience|Engineering, Biomedical http://docs.lib.purdue.edu/dissertations/AAI3556646 http://docs.lib.purdue.edu/dissertations/AAI3556646 Wed, 22 May 2013 15:52:46 PDT In this work permanent magnet inductors for dc biased inductor applications are considered. The inductor designs utilize the persistent flux of a permanent magnet to partially offset the flux in the magnetic core due to current in the winding. The addition of the permanent magnet allows for decreased inductor mass for a given inductor current, loss, and inductance rating. This dissertation presents the first formal optimization of permanent magnet inductors. Optimized inductor designs are achieved using a population-based, multi-objective optimization algorithm in which the design parameters consist of the permanent magnet material type and geometry of the magnetic core, conductor, and permanent magnet. By comparing Pareto-optimal fronts, it is shown that the mass of a permanent magnet inductor is significantly less than that of a traditional EI core inductor for a given loss. Then, an optimization algorithm of a dc-dc power converter utilizing a permanent magnet inductor is presented. The algorithm includes both a magnetic and thermal analysis.^

]]> Grant M Shane Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI3556647 http://docs.lib.purdue.edu/dissertations/AAI3556647 Wed, 22 May 2013 15:52:46 PDT Osteoarthritis (OA), a debilitating disease starts at the articular surface of cartilage and deteriorates the entire joint. This clinical need has yet to see a conclusive treatment. While etiologies and exact molecular mechanisms that cause this chronic disease remain elusive, key pathophysiological changes occurring during the degradation process have been identified. Of these, loss of aggrecan, a major proteoglycan in cartilage, is considered to occur first, after which other cartilage matrix components become extremely susceptible to enzymatic degradation. Therapies that protect the matrix from degradation have been proposed as ideal candidates to mitigate the inflammatory cycle of OA. ^ To address this clinical need, our laboratory has designed molecules, coined peptidoglycans, modeled to functionally mimic proteoglycans and limit proteolytic degradation. This dissertation studied the efficacy of two such peptidoglycans, consisting primarily of a chondroitin-6-sulfate backbone functionalized with either hyaluronan or collagen type II binding peptides, as a potential therapy to prevent cartilage degradation and promote repair. These peptidoglycans are able to directly adhere to cartilage extracellular matrix components and are less prone to proteolytic cleavage. The efficacy of these peptidoglycans were tested in three different cartilage degradation models: type I collagen scaffolds seeded with chondrocytes and stimulated with interleukin-1β, trypsin treated cartilage explants stimulated with interleukin-1β and cartilage explants treated with synovial fluid from OA patients. ^ Our findings indicated the ability to enhance bulk mechanical properties in collagen scaffolds and aggrecan depleted cartilage explants. In addition the mimic shows the ability to prevent cytokine induced degradation and modulate anabolic (collagen type II and aggrecan) and catabolic (MMP-13 and ADAMTS 5) gene expression of chondrocytes. ^ The findings in this dissertation support our hypothesis that by reducing fragmentation of matrix components during the early stages of OA, the inflammatory cycle can be curbed. This technology shows promising potential to be pursed further as a treatment in early stage OA, preventing excessive cartilage damage and providing a healthy environment for tissue repair and regeneration.^

]]> Shaili Sharma Engineering, Biomedical http://docs.lib.purdue.edu/dissertations/AAI3556586 http://docs.lib.purdue.edu/dissertations/AAI3556586 Wed, 22 May 2013 15:52:45 PDT This dissertation includes three essays under the topic of restaurant crisis management in relation to food safety events. Due to the devastation impact of food safety events on firms and consumers, it is vital to understand the impact of the events as well as the mechanism of crisis communication. Three papers examine the financial impact of food safety events on firms, media coverage about food safety events, and the role of social media in communication. ^ The first paper examines the impact of food safety events on financial performance of firms using an event study method. The event study method enables to examine firms' stock prices in response to 40 food safety events over the past 25 years in the U.S. Results demonstrated the magnitude and duration of the impact of food safety events on firm value. The study also revealed that firm-specific factors (firm size, past history) and situational factor (media attention) are significant drivers influencing the magnitude of the impact of food safety events. ^ The second study investigates media coverage about food safety events occurred in the past 25 years in the U.S. using a content analysis. By combining situational crisis communication theory (SCCT) and stakeholder theory (ST), the study examined the media reporting patterns focusing on instructing information, response strategies, stakeholders, and media frames as well as the effect of situational factors (crisis responsibility and severity of risk) on these reporting patterns. Based on the analysis of sixty seven news articles, the results reveal the tendency of restaurant firms to be proactive rather than passive. Regulatory agencies were found to be most primary stakeholders during a crisis, followed by victims, customers, suppliers, employees, legal professionals, and shareholders. The salient media frames were found to be vulnerability, history, and emotion. The effect of situational factors was also supported on the media reporting patterns. ^ The third essay deals with the role of social media comments about food safety information on consumer responses. By adopting and extending the dual-process model, the study examined the effect of three components of social media comments: source credibility, the content of comments, and relationship quality. Using a scenario-based survey, the study found significant interaction effects between source credibility and comment content. Although negative comments induced negative responses regardless of source credibility, positive or mixed comments led to less negative responses when the source is highly credible than when the source is less credible. The insignificant effect of relationship quality signified a stronger influence of information itself compared with the influence of the person delivering information. ^ The three papers highlight various aspects of restaurant crisis management in response to food safety events. The use of different methods (event study method, content analysis, and scenario-based survey) extends the magnitude of food safety research which may become an useful guideline for future studies on food safety.^

]]> Soobin Seo Business Administration, Management|Mass Communications http://docs.lib.purdue.edu/dissertations/AAI3556587 http://docs.lib.purdue.edu/dissertations/AAI3556587 Wed, 22 May 2013 15:52:45 PDT Purpose: The objective of the research is to determine the feasibility of the prototype photoacoustic scanner to quantify localized blood perfusion and fractional plasma volume in vivo utilizing an exogenous dye within a breast cancer xenograft tumor model coupled with a dynamic contrast enhanced imaging protocol. ^ Methods and Materials: The prototype photoacoustic scanner was tested for motion artifacts during individual scans that exceeded the 154 micron theoretical spatial resolution utilizing phantoms. The laser optical delivery system was also tested and optimized to minimize non-uniformities over the field of view. An isoflurane anesthetic delivery and scavenge system were designed and added to the scanner. Animal models were developed using the breast cancer cell lines MB-MDA-231 and BT-474. These were xenografted onto athymic nude mice. A synthesized arterial input function was produced utilizing measurements obtained with DCE-CT scans. 4D image coregistration was performed to allow for measuring identical regions between DCE-CT and DCE-PCT scans. This data was then able to be used for compartmental modeling of dynamic contrast enhanced photoacoustic data. The perfusion and fractional plasma volume values as determined by DCE-PCT were then able to be compared to the values as measured by DCE-CT. A series of fiber optic dosimetry probes were also fabricated and calibrated to aid in measuring laser fluence within the photoacoustic scanner. ^ Results: The photoacoustic scanner was adjusted to have in scan motion less than that of the theoretical spatial resolution. The synthesized arterial input function was determined to have the same general shape, and peak timing as that of individual arterial input functions measured by both DCE-CT and DCE-PCT scans. A fiber optic dosimetry probe with a diameter of 1.5mm and a concentration of 5mg/mL titanium dioxide was determined to yield a coefficient of variation of ∼7%. Compartmental fitting after coregistration was performed to determine blood perfusion and fractional plasma volume. ^ Conclusion: This study explored the feasibility of a prototype photoacoustic scanner to quantify localized blood perfusion and fractional plasma volume in vivo using a dynamic contrast enhanced imaging protocol in a xenograft tumor model. The perfusion and fractional plasma volumes determined by DCE-PCT did not obtain statistically significant correlation to those same measurements as determined by DCE-CT.^

]]> Michael Richardson Shaffer Health Sciences, Radiology|Health Sciences, Oncology http://docs.lib.purdue.edu/dissertations/AAI3556585 http://docs.lib.purdue.edu/dissertations/AAI3556585 Wed, 22 May 2013 15:52:44 PDT The speed and efficiency of information processing in conventional charge based field effect transistors have progressed dramatically in the last 50 years due to scaling of transistor dimensions. However, the fundamental scaling limits of this technology are threatening to halt this progress; leading to an enormous interest in alternative computation schemes and devices. All-spin logic (ASL) is one such alternative approach to information processing where information is stored in the magnetization of nanomagnets coupled by spin coherent channels. We developed an experimentally benchmarked spin-coupled multi-magnet simulator to investigate two major aspects of ASL operation. Firstly, we evaluated the energy (E) delay (τ) performance metric of ASL switches and found that similar to transistors, Eτ = Q²R where R is the resistance of the device and Q, total charge supplied by the power supply in the switching process is proportional to the number of Bohr Magnetons comprising the magnet. Secondly, we found that the inbuilt non-reciprocity in ASL allows cascading them to form spin-coupled multi-magnets networks (SMN) where universal logic gates, ring oscillator and other interesting circuits can be implemented. These circuits seem difficult to implement experimentally at this time, since the large magnets used today require very high threshold spin signal to switch. Hence, for ease of experimental implementation, we proposed a different class of devices which could operate at sub-threshold bias; but still rely on the spin torque based interaction between nanomagnets. We have also developed a generic framework that can be used to understand the results of such sub-threshold experiments on spin-coupled multi-magnets networks.^

]]> Angik|Fairbairns Sarkar Engineering, Electronics and Electrical|Nanoscience|Information Science http://docs.lib.purdue.edu/dissertations/AAI3556583 http://docs.lib.purdue.edu/dissertations/AAI3556583 Wed, 22 May 2013 15:52:43 PDT Tissue Engineering (TE) is the interdisciplinary field that focuses on developing strategies for creating functional and healthy tissue for the replacement and regeneration of damaged organs and tissue. One strategy in this area is to use hydrogels as temporary scaffolds for cell growth and differentiation using biomimetic materials such as collagen peptides. Collagen is one of the most abundant proteins found in the connective tissue of mammals providing physical support for cell growth. A key feature of collagen is the ability of single peptide strands to acquire a triple helical conformation, critical for the subsequent self-assembly into high order fibers and fibrous networks in nature. Therefore, in this study a hydrogel system was designed by conjugating collagen peptides to an 8-arm polyethylene glycol star polymer to yield hydrogels via the physical cross-linking of the collagen triple helices. Various physical characterization studies proved that this collagen peptide-based hydrogel possessed desirable viscoelastic and biocompatible properties to function as a 3D matrix with the potential to induce differentiation of the mesenchymal stem cells (MSCs). It was also found that the hydrogel had a thermoresponsive feature that could be tuned when altering the collagen peptide sequence. Also in this work, another collagen-based materials were designed to self-assemble into supramolecular structure via aromatic interactions. For this purpose, we attached various aromatic molecules in the middle of the peptide sequence in a radial-mediated design that yielded various structures such as hollow spheres and insoluble fibers. ^ In the last part of this work, the synthesis of small peptidomimetic molecules targeted against anthrax protective antigen will be discussed. Protective antigen plays an important role during anthrax infection by oligomerizing into a pore structure that translocates other anthrax toxins inside of the cells. For this reason, various small molecules were designed by the CAVEAT computer software to target the oligomerization process, synthesized and evaluated in a biological assay. One of the molecules was able to modestly rescue a macrophage cell line from anthrax toxin-induced cell death, and is one of the few examples of small molecules targeted against the pore formation of protective antigen.^

]]> Charles M Rubert Perez Chemistry, General|Chemistry, Biochemistry http://docs.lib.purdue.edu/dissertations/AAI3556584 http://docs.lib.purdue.edu/dissertations/AAI3556584 Wed, 22 May 2013 15:52:43 PDT Settlement controls the design of piles in most cases because, by the time a pile has failed in bearing capacity, it is very likely that serviceability will have already been compromised. This notwithstanding, pile foundations are often designed based on the calculations of ultimate resistances reduced by factors of safety. This is in part due to the lack of accessible realistic analysis tools for estimation of settlement, especially for piles installed in layered soil. ^ In this research, analytical and semi-analytical methods of analysis of axially loaded piles in multilayered soils are developed. First, the governing differential equations for an axially loaded pile in a multilayered, linear elastic soil are derived using the principle of minimum potential energy. The analytical solution to the governing differential equations is obtained by determining the unknown integration constants using the boundary conditions, Cramer's rule, and a recurrence formula. Then the governing differential equations are rederived with consideration of the spatial variation of the shear and bulk modulus in the soil surrounding the pile using a modified hyperbolic constitutive model. While the governing differential equation for the pile remains the same as that of the linear analysis, the governing differential equation for the soil changes, and its solution is obtained using the finite difference method. ^ The pile base load-settlement analysis is developed based on the analytical solution for a rigid, circular punch on the surface of an elastic half space. After each load increment, the values of the equivalent linear-elastic parameters reflecting the updated level of strain at every discretization node in the soil mass below the pile base are obtained using a modified hyperbolic model. Representative values of the shear and bulk moduli within the zone of influence below the pile base, which are used as input in the rigid punch solution, are then obtained using the distortional and volumetric energies as weighting factors. ^ Good agreement is obtained between results of the nonlinear analyses of a nondisplacement pile in sand with different relative densities and those from finite element analysis of the limit unit shaft resistance of nondisplacement piles using an advanced constitutive model available in the literature. In addition, results of the pile base load-settlement analysis are in good agreement with results of plate load tests performed in a calibration chamber and of finite element analyses available in the literature. The developed analyses provide useful insights on the effect of soil layering and slenderness ratio on the load-settlement response of axially loaded piles and can be performed at only a small fraction of the time required for an equivalent three-dimensional finite element analysis.^

]]> Ho Young Seo Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI3556582 http://docs.lib.purdue.edu/dissertations/AAI3556582 Wed, 22 May 2013 15:52:42 PDT Improving pharmaceutical research and development (R&D) strategies to increase productivity and reduce expenditures is one of the most important issues facing the pharmaceutical industry today. With heightened pressure from regulatory agencies, loss of revenue due to patent expirations, and an evolving healthcare system, companies must become more efficient at bringing new molecules to the market. Currently, a considerable amount of emphasis is being placed on improving efficiency and productivity in the early stages of discovery and development with an aim to decrease attrition rates of compounds in late-stage clinical development. Compounds that fail at this stage generally do so because of poor oral bioavailability (Phase I), lack of efficacy in vivo (Phase II and III), or unexpected toxicity that was not predicted or observed based on animal models (Phase II and III). In order to reduce the number of failures, better in vitro and in vivo models are needed in preclinical development to characterize the properties and predict the developability of new molecular entities (NMEs). ^ The need for improving preclinical testing by focusing on translation/prediction of clinical outcomes has long been considered an area of critical need for the pharmaceutical industry. This dissertation focuses on the optimization and utilization of two preclinical models that can be used to screen NMEs for optimal development properties. The first section (Chapters 1 and 2) discusses the use of the Caco-2 cell line as an in vitro model to predict the absorption of orally administered drugs. Chapter 1 primarily focuses on background information and explains the major advantages and limitations of utilizing the Caco-2 model in preclinical studies. Chapter 2 discusses the problem of variability associated with the Caco-2 cell line with a specific emphasis on variability associated with cell culture conditions, an issue that often limits inter- and sometimes intra-laboratory comparisons. A detailed study is presented in which two Caco-2 sources, were cultured with different growth media. Differences in drug transporter and metabolizing enzyme mRNA expression and functional transport data as a function of source and media were determined. ^ The second section of this dissertation (Chapters 3, 4, and 5) focuses on the utilization of the porcine model as a potential in vivo screening tool for preclinical pharmacokinetic (PK) testing. Chapter 3 explains the rationale behind utilizing pigs as preclinical animal models, including a comparison of the gastrointestinal tracts of various mammalian species that are currently used during pharmaceutical testing. Additionally, Chapter 3 examines PK testing and analysis of the antibiotic rifampin in both adult and juvenile pigs. Results indicated significant similarities between the PK of pigs and humans. Furthermore, age-based changes in porcine PK correlated well with age-based changes in human PK. Based on these similarities, we hypothesized that juvenile pigs could be used as preclinical surrogates for human children during pediatric drug development and PK testing. Consequently, Chapters 4 and 5 discuss the development, optimization, and in vivo characterization in juvenile pigs of novel pediatric dosage forms of rifampin. Chapter 4 examines the feasibility of orally disintegrating films (ODFs), while Chapter 5 focuses on orally disintegrating tablets (ODTs) of rifampin. Finally, Chapter 6 provides brief concluding remarks and offers future perspectives on the projects presented in this dissertation. It is our laboratory's working hypothesis that a better understanding of the advantages and limitations of preclinical models will allow pharmaceutical scientists to increase efficiency and decrease compound attrition during drug development.^

]]> Wyatt James Roth Health Sciences, Pharmacy http://docs.lib.purdue.edu/dissertations/AAI3556580 http://docs.lib.purdue.edu/dissertations/AAI3556580 Wed, 22 May 2013 15:52:41 PDT Severe convective storms—and the tornadoes, hail, and damaging winds that they produce—represent a real risk to life and property in the United States. In 2011, tornadoes claimed over 540 lives over 15 different states, the fourth highest toll on record. It is not known whether 2011 represents a positive trend in the frequency of severe thunderstorms and associated phenomena because of the many uncertainties in the historical record. This study seeks to examine a method developed to study these severe phenomena using a high-resolution numerical weather prediction model driven by large-scale reanalysis and employing an artificial neural network. Specifically, high resolution simulations of the Weather Research and Forecasting model, forced by data from the NCEP/NCAR Reanalysis Project are used to generate daily re-forecasts of every day in April, May, and June over 1990–2009. These simulations are examined at hourly intervals for the presence of severe convection through the use of an artificial neural network that was trained using days from ten years of modeled data that coincided with observed days of severe weather. This network is applied over all twenty years of data in order to examine the modeled trends in severe phenomena. Tests are also performed to examine the sensitivity of the modeling procedure to various parameters including integration time, land surface heterogeneity, and model physics. Results indicate that, contrary to the biased observational record, there has been no statistically significant change in the frequency of warm season severe weather occurrences in the eastern two-thirds of the United States over 1990–2009. Further, sensitivity tests indicate an approach with more frequent re-initializations of the model produces a more physically realistic climatology of severe convective events, and that this climatology is fairly insensitive to small changes in the land surface and model physics. A similar result is found for the spatial distribution of heavy and extreme rainfall events.^

]]> Eric D Robinson Atmospheric Sciences http://docs.lib.purdue.edu/dissertations/AAI3556581 http://docs.lib.purdue.edu/dissertations/AAI3556581 Wed, 22 May 2013 15:52:41 PDT The purpose of this study was to determine Engineering/Technology Education (ETE) teachers' perceptions of Project Lead The Way's (PLTW) pre-engineering program in the state of Indiana utilizing the Characteristics of Technology Education Survey (CTES) (Daugherty, Hill, & Wicklein, 1996). The study focused on the perceptions of teachers who were and were not teaching PLTW's pre-engineering curriculum as they related to curriculum content, teaching methodology, curriculum integration, and fit of curriculum in school environment. Two hundred and eighty two or 51.3% of Indiana high school ETE teachers responded to the 46 question CTES. Analysis of variance (ANOVA) and multivariate analysis of variance (MANOVA) were conducted to test for significance. The study found no significant differences in the perceptions of ETE teachers who were and who were not teaching PLTW's pre-engineering program.^

]]> Steven E Rogers Education, Industrial|Education, Vocational http://docs.lib.purdue.edu/dissertations/AAI3556578 http://docs.lib.purdue.edu/dissertations/AAI3556578 Wed, 22 May 2013 15:52:40 PDT Concussions are a common injury in many contact sports, and their prevalence has led many athletes and sports physicians to consider them minor. However, athletes who sustain concussions are at risk for a number of further injuries. These injuries include but are not limited to further concussion due to their present mental impairment, early onset of dementia, sudden death or catastrophic injury due to the condition known as 'second impact syndrome,' and persistent mood disorders. In order to prevent these cumulative effects of concussion, the initial injury must be correctly identified so that the player can be removed from play for rest and observation. Current field tests are not sufficient to reliably detect symptoms of concussion, and thus allow players that should be removed from the game to continue playing and risk further injury. To further complicate this matter, our work shows that, in addition to concussion, subconcussive blows to the head have injurious effects which can be measured using functional magnetic resonance imaging (fMRI). FMRI is a powerful tool for exploring the nature of these injuries, however, fMRI is an expensive technique, and it not appropriate for a field diagnostic. Therefore, this work will present both an exploration of subconcussive injuries using fMRI, as well as a prototype for a new field-appropriate diagnostic tool intended to be sensitive to both classic concussion and these newly discovered subconcussive injuries, and preliminary results on its effectiveness.^

]]> Meghan Elizabeth Robinson Engineering, Biomedical http://docs.lib.purdue.edu/dissertations/AAI3556579 http://docs.lib.purdue.edu/dissertations/AAI3556579 Wed, 22 May 2013 15:52:40 PDT The over-reliance and continued use of glyphosate as the sole mechanism for weed control has led to the selection of glyphosate-resistant weeds. New trait technology incorporating 2,4-D tolerance in soybean will provide an alternative method to control weeds that are hard to control with glyphosate alone and reduce selection pressure by tank mixing herbicides with 2,4-D, but the response of aryloxyalkanoate dioxygenase-12 (AAD-12) transformed soybean have not been evaluated. In addition, off-site movement of auxinic herbicides on sensitive soybean will be of greater concern as 2,4-D and dicamba will be applied at a field-scale level during the peak growing season with new transgenic crops becoming commercially available in the near future. The purpose of my research was to quantify the effects of 2,4-D timing and rates on AAD-12 soybean yield components and AAD-12 protein expression; characterize the effects of dicamba and 2,4-D rates on sensitive soybean plants; and analyze the effect of 2,4-D plus glyphosate on summer annual weeds. It is conclude that 1) AAD-12 soybean plants can tolerate up to 2,240 g ha^-1 2,4-D. Seed yield, seed mass, pod number, seed number, seed per pod, reproductive node number, pods per reproductive node, node number, and percent reproductive nodes were not affected by 2,4-D when applied at the V5, R2, or the V5 followed by the R2 soybean growth stages of AAD-12 soybean plants. 2) The youngest fully emerged trifoliate in the DAS-68416-4 event had the highest AAD-12 expression, with means ranging from 369 to 390 ng cm^-2, while the older leaves maintained a lower level of expression, 171 to 211 ng cm^-2. The youngest leaves of event DAS-21606-3 had the highest level of AAD-12 protein expression (205 to 225 ng cm^-2), while the level of AAD-12 was lower in older leaves (71 to 149 ng cm^-2). In general, 2,4-D treatments did not reduce AAD-12 protein expression at 3, 7, 14, and 21 days after treatment; however, in a few instances AAD-12 protein expression was increased or decreased by 8 to 11% after 2,4-D treatment. 3) Glyphosate at rates ≥ 840 g ha^-1 controlled giant ragweed, common lambsquarters, common waterhemp, and velvetleaf by 94 to 100%. Giant ragweed was controlled 99 to 100% by 2,4-D alone when rates were ≥ 280 g ha^-1. Common lambsquarters, common waterhemp, and velvetleaf control increased as 2,4-D rates increased, with 1,120 g ha^-1 providing 90 to 94% control. 4) Sensitive soybean seed yield was reduced by 5% when 87 to 116 g ha^-1 2,4-D was applied and a 10% reduction was caused by 149 to 202 g ha^-1 2,4-D. 5) Dicamba treatments applied to sensitive soybean reduced seed yield by 5% from 0.042 to 0.528 g ha^-1 and a 10% reduction was caused by 0.169 to 1.1 g ha^-1 dicamba. Path analysis indicated that seeds m^-2, pods m^-2, main stem reproductive nodes m^-2, and main stem nodes m ^-2 were the most influential yield components in seed yield formation when either 2,4-D or dicamba treatments were applied to sensitive soybean plants. The introduction of 2,4-D-tolerant crops will allow add an addition method to control weeds that are resistant to glyphosate while not altering reproduction, but precautions need to be taken to avoid injury to nearby sensitive plants.^

]]> Andrew P Robinson Agriculture, Agronomy|Agriculture, General|Agriculture, Plant Culture http://docs.lib.purdue.edu/dissertations/AAI3556577 http://docs.lib.purdue.edu/dissertations/AAI3556577 Wed, 22 May 2013 15:52:39 PDT My research, situated in writing centers, focuses on oral response to L2 writing. I used conversation analysis (CA) to describe and analyze 23 video-recorded interactions between graduate-student tutors and graduate-student L2 tutees. Analyses focused on the sequential nature of talk-in-interaction and the strategies used by interactants to initiate, continue, and repair interactions. ^ Analyzed descriptions are provided of the structure and function of three of the four components of tutorials—the opening, agenda-setting, and closing components. Opening components include (minimally) summons and responses. Additionally, they may include greetings, introductions, identity checks, invitations to begin the tutorial, small talk, and institutional business. Agenda setting components typically include determining the what, the priority, and the how of the agenda and may also include institutional business. Finally, closing components may begin with possible pre-closings such as assessments, time checks, and "anything else?" questions. Closing components must include a terminal sequence; however, they may also include summaries, prescriptions, appreciations, and institutional business. ^ Analyses reveal tensions caused by inequalities or perceived inequalities in epistemic authority and interactants orientation to those inequalities. Discussion explores what it means to be an international student with sufficient educational capital to be accepted into a program at a research university in the U.S. but still struggle without the "new" educational capital required. Analyses also reveal that writing center tutors need more effective training. In particular, tutors should spend the first few minutes learning about the tutee and informing the tutee about the writing center tutorial. ^ Future research should focus on tutorials in a variety of institutions of higher learning with participants including both L1 and L2 undergraduate, graduate, and adjunct-faculty tutors and tutees. Differences and similarities among immigrants, international students, and other L2 participants (both tutees and tutors) must be examined. More comparisons also need to be made about first time and returning tutees including the schemas they have or have not developed and their expectations for the tutorial. Finally, we need to know more about how the genre of the text affects the trajectory and outcome of the tutorial.^

]]> Laurel Denise Reinking Education, Bilingual and Multicultural|Speech Communication|Language, General http://docs.lib.purdue.edu/dissertations/AAI3556576 http://docs.lib.purdue.edu/dissertations/AAI3556576 Wed, 22 May 2013 15:52:38 PDT A relative orbit control concept for collocated geostationary spacecraft is presented. One chief spacecraft, controlled from the ground, is responsible for the orbit determination and control of the remaining vehicles. Any orbit relative to the chief is described in terms of equinoctial orbit element differences and a linear mapping is employed for quick transformation from relative orbit measurements to orbit element differences. It is demonstrated that the concept is well-suited for spacecraft that are collocated using eccentricity-inclination vector separation and this formulation still allows for the continued use of well established and currently employed stationkeeping schemes, such as the Sun-pointing-perigee strategy. The relative approach allows to take determinisitc thruster cross-coupling effects in the computation of stationkeeping corrections into account. The control cost for the proposed concept is comparable to ground-based stationkeeping. A relative line-of-sight constraint between spacecraft separated in longitude is also considered and an algorithm is developed to provide enforcement options. The proposed on-board control approach maintains the deputy spacecraft relative orbit, is competitive in terms of propellant consumption, allows enforcement of a relative line-of-sight constraint and offers increased autonomy and flexibility for future missions.^

]]> Raoul R Rausch Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI3556575 http://docs.lib.purdue.edu/dissertations/AAI3556575 Wed, 22 May 2013 15:52:37 PDT Radiation transfer in turbulent reacting and non-reacting flows is important in many applications related to combustion, energy, power and propulsion, and atmospheric sciences. Advanced measurements and computations of radiation transfer in turbulent reacting flows have applications in improving energy efficiencies, managing emissions to the environment, and controlling radiation from unwanted fires. Emerging large-scale computations can benefit from the development of highly scalable quantitative visualization methods for volume rendering and displaying three-dimensional time-dependent results in the form of planar images with consideration of time and length scales that vary over orders of magnitude. ^ Experimental and theoretical methods for quantitatively comparing measured and modeled time-dependent images of the infrared radiation intensity from reacting flows are developed and applied to a range of example problems. Quantitative images of the radiation intensity from bluff body stabilized laminar diffusion flames and turbulent jet diffusion flames are acquired using a high speed infrared camera. Results of the solution to the radiative transfer equation are rendered in the form of planar images using a narrowband radiation model with computed scalar values. ^ Quantitative comparisons of the measured and modeled images of the radiation intensity from the reacting flows are shown to be useful for prompting improvements in combustion and radiation models and interpreting distributions of gas temperatures, gas species concentrations, and particulate volume fractions. The application of emerging imaging techniques to direct numerical simulation and large eddy simulation results is defining a new field and is one of the novel contributions of this work.^

]]> Brent A Rankin Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI3556574 http://docs.lib.purdue.edu/dissertations/AAI3556574 Wed, 22 May 2013 15:52:37 PDT With the surges in international trade, the threat of invasive wood-boring longhorned beetles continues to increase. These beetles could potentially cause damage worth hundreds of millions of dollars as has been demonstrated by the Asian longhorned beetle. While we cannot conduct realistic invasion experiments, we can study the behavioral traits of the native longhorned beetles. The longhorned beetles are a good study group of potential invaders because their diversity results in great variation in biological and behavioral traits. The aims of this project were to construct a molecular phylogeny of the longhorned beetles that are native to the Midwestern U.S. and to map biological and behavioral traits onto this phylogeny. During the first step of collecting the beetles we set up traps on private forest lands. We studied the relationship between forest productivity and longhorned beetle communities. Our results suggest that the numbers of both the pest and the harmless species increase with decreasing forest productivity. Chapter 1 deals with this change in communities with forest health. Chapter 2 deals with the species Sternidius alpha, which is common in the eastern part of the United States. Two populations of Sternidius alpha that differed in color were collected from two geographically disjunct Indiana sites. One population was red and the other gray. The technique of DNA barcoding employed in our laboratory separated the red and gray beetles into different phylogenetic clades. In Chapter 3, a phylogeny of all the longhorned beetle species collected was inferred based on partial DNA sequences from two mitochondrial genes: 12S ribosomal RNA and cytochrome oxidase subunit I. Maximum Likelihood and Bayesian inferences were used for building a phylogenetic tree. All of the subfamilies in the family Cerambycidae were monophyletic, which supports the delineation of the subfamilies based on morphological characters. An unexpected result, however, was the placement of the subfamily Prioninae, as a derived sister of the subfamily Cerambycinae. This contrasts with the previous finding that suggest Prioninae is basal to most of the remaining subfamilies of the Cerambycidae. Also, the subfamily Lamiinae, thought to be a sister to the subfamily Cerambycinae on the tree based on morphology, did not have a sister subfamily on the molecular tree. In Chapter 4, an ultrametric Bayesian algorithm was used to reconstruct the ancestral states on the phylogenetic tree of the longhorned beetles. This analysis showed that the inferred ancestral longhorned beetle was probably a polyphagous feeder as a larva on long dead and decaying angiosperms and non-feeding as an adult. As the lineages diversified over time this ancestral biology gave rise to other traits as well, although some species retained the traits that the ancestor displayed. In Chapter 5, the ultrametric Bayesian tree was used to calculate the extent of phylogenetic signal in the phylogenetic tree for various biological traits. The phylogenetic signal was strong for the following traits: host condition for larval feeding, adult feeding behavior, plant part attacked, the plant tissue attacked and the utilization of angiosperms or gymnosperms. The presence of phylogenetic signal in the first four traits was used to build a threat index to predict which newly introduced species could be capable of becoming invasives. Study of the invasion-promoting traits among native species can be useful in predicting which of the relatives of the native species are likely to share a suite of traits that could enable them to become invasive.^

]]> Kapil R Raje Biology, Entomology http://docs.lib.purdue.edu/dissertations/AAI3556572 http://docs.lib.purdue.edu/dissertations/AAI3556572 Wed, 22 May 2013 15:52:36 PDT In animals and humans, temporal processing of acoustic features is critical for perception of species-specific sounds and speech. Time varying sound features are often represented in the early auditory pathway as stimulus-synchronized patterns of neural activity. These representations undergo transformation as they pass from the inferior colliculus (IC) to auditory cortex via the medial geniculate body (MGB). IC responses preserve their synchronized inputs but show much greater firing rate modulation than many of their inputs. How the inputs to IC converge to generate tuned rate and temporal coded response patterns is poorly understood. In the MGB, two different responses are observed: Stimulus-synchronized responses faithfully preserve the temporal coding from its afferent inputs, and Non-synchronized responses, which are not phase locked to in the inputs, represent changes in temporal modulation by a rate code. The cellular mechanisms that produce these segregated responses are also poorly understood. ^ Single compartment neuron models of the IC and MGB were created using MATLAB and NEURON software. The most commonly observed IC response subtypes were recreated, enabling dissociation of inherited response properties from those that were generated in IC (Rabang et al., 2012). ^ The MGB model investigated the role of two differing populations of excitatory inputs, feedforward inhibition, and synaptic plasticity on the generation of either synchronized or non-synchronized responses (Rabang and Bartlett, 2011). Patch clamp recordings from MGB neurons verified synaptic model parameters. Both models recreated in vivo responses and made predictions about the role of inhibition in normal hearing and age-related hearing loss.^

]]> Cal F Rabang Biology, Neuroscience|Engineering, Biomedical http://docs.lib.purdue.edu/dissertations/AAI3556573 http://docs.lib.purdue.edu/dissertations/AAI3556573 Wed, 22 May 2013 15:52:36 PDT Grassroots innovations are creative technological solutions for problems occurring in local communities. The present study explains how individual members of local communities organize the design and development of technological solutions at the grassroots despite being severely limited in their access to technological, scientific and economic resources. The actors, sites and practices associated with grassroots innovation present unique opportunities for researchers interested in: (a) studying technology design for the purpose of achieving development; (b) understanding how knowledge is performed, created and shared outside and at the interface with formal organizational and epistemic boundaries; and (c) investigating the ethical premises on which individuals choose to contribute private effort toward the collective good. Contemporary research on the design of technologies for development overlooks the technological capabilities of grassroots community members by categorizing them as users rather than as independent designers of technology. This study addresses the paucity of scholarship on local epistemologies of technology design and use by identifying the ways in which members of grassroots communities collaborate to produce technological solutions for locally occurring problems. Based upon a critique of the literature on the design of technology for development and a discussion of the literature on the social construction of technology and the communicative constitution of knowledge in organizations, I establish a theoretical and methodological framework grounded in the observation and interpretation of practices of participation in technology development as manifest through artifacts, everyday routines and public rituals across multiple geographical sites. Data collection for this study involved ethnographic research conducted in India over three months across twenty five physical sites and two states. During the first phase of data collection I participated in a five-day shodh yatra on foot across 19 rural communities in India with members of the Honey Bee Network—a quasi-governmental organization involved in organizing the development of grassroots innovations. Leveraging the access gained to grassroots innovators and members of the Honey Bee Network during the shodh yatra, I conducted participant observation of eight key innovators as my primary informants. As a participant-observer, I lived with grassroots innovators and learned about the ways in which they develop novel, affordable technological solutions for problems in their local communities. In addition, I interviewed innovators' family members, peers and collaborators of innovators, within and outside the local community. Extensive archival data on the primary informants was obtained through the Honey Bee Network which provided access to documents and also organized initial access to the primary informants. ^ Findings indicate that a variety of epistemic practices (Knorr Cetina, 2008) exemplify the situated, empathic and reflexive character of technology design at the grassroots. The development of grassroots innovations is often accompanied by an empathic design process in which innovators leverage their embeddedness in local communities to observe and reflect on users' technology-related behavior in naturalistic settings. Grassroots innovators are active in perceiving and actively seeking to address the needs of others. They generate incremental improvements in the functionality and aesthetics of technology artifacts through active prototyping. The actual design process rarely involves detailed representation or the use of precise measurements and calculations. Instead, innovators tend to rely on oral communication with close collaborators. The frugal use of locally available materials enables a high level of adaptation to the physical and social environment. Grassroots technologies can also be flexibly adapted to diverse heterogeneous use cases. The social organization of grassroots innovations indicates that grassroots innovators are not unaided in their efforts to develop innovative technologies. They acquire important instrumental (e.g., expertise, skills, capital) and relational (e.g., reciprocity, status) resources through early socialization into the family occupation, and participation within occupational communities whose membership is determined by caste and training. Innovation development requires the innovator to make increasingly public claims to important instrumental and relational resources embedded in the physical and social environment. The publicness of innovation depends on the innovator's ability to articulate collaboration with peers and external institutions in the empathic and participative sense of cooperation. Grassroots innovators frequently express the need for innovation in terms of a perceived responsibility toward their local communities. They may even eschew monetary benefits from the protection and sale of their intellectual property. Instead, many grassroots innovators freely reveal their designs to user communities and support the imitation of their designs by others. The preference for sharing knowledge in an open manner is associated with the adoption of an empathic cooperative or instrumental aid-oriented approach to collaboration. The organization of grassroots innovations represents a community-based and user-driven model of innovation based on empathy and social responsibility which problematizes rational, economic models of competitive innovation for profit that are prevalent in the industry and the innovation literature.^

]]> Prashant Rajan Speech Communication|Sociology, Organization Theory|Sustainability http://docs.lib.purdue.edu/dissertations/AAI3556570 http://docs.lib.purdue.edu/dissertations/AAI3556570 Wed, 22 May 2013 15:52:35 PDT This study examined how first-year undergraduates' family background characteristics (i.e., first-generation status and low family income) and individual attributes (i.e., sex, motivation, and best friend attachment) are related to institutional integration (faculty and student integration). Low and non-low family income students (N = 961) completed (a) demographic items, (b) the Institutional Integration Scale, (c) the Academic Intrinsic Motivation Scale, (d) best friend questions, and (e) the Relationship Structures Questionnaire. Hierarchical multiple regressions tested the two hypotheses: (a) mother and father education, family income, student sex, motivation, and best friend attachment avoidance and anxiety will contribute uniquely and significantly to student integration; and (b) mother and father education, family income, student sex, motivation, and best friend attachment avoidance and anxiety will contribute uniquely and significantly to faculty integration. Regression results revealed that the hypotheses were partially supported. For hypothesis one, motivation contributed significantly, uniquely, and positively to student integration, and sex and best friend attachment avoidance contributed significantly, uniquely, and negatively to student integration; that is, high motivation, being a woman, and low best friend avoidant attachment contributed uniquely to high student integration. For hypothesis two, income contributed significantly, uniquely, and negatively to faculty integration, and motivation contributed significantly, uniquely, and positively to faculty integration. That is, low family income contributed to high faculty integration, and high motivation contributed to high faculty integration. These findings have implications for college counseling, academic advising, and first-year undergraduate programming and orientation practices.^

]]> Catherine Pilotte Education, Guidance and Counseling|Psychology, Counseling|Education, Higher http://docs.lib.purdue.edu/dissertations/AAI3556571 http://docs.lib.purdue.edu/dissertations/AAI3556571 Wed, 22 May 2013 15:52:35 PDT Delayed senescence in plants is often described as stay-green. Stay-green has been identified in several grain crops including maize, and has been associated with abiotic stress tolerance in some of these crops. In this study, several populations of maize were analyzed to find evidence of functional stay-green and define the genetic mechanisms causing this phenomenon. Functional stay-green was found within a set of temperate maize germplasm. The maize inbred lines Mo20W, LH123HT, and PHG35 exhibited different types of increased functional stay-green. Hybrids created from Mo20W also exhibited the functional stay-green phenotype. Two separate advanced backcross recombinant inbred line mapping populations were created with Mo20W as one parent and B73 and Mo17 as the recurrent parents. These populations were tested in three environments under drought and high temperature stress. The ratio vegetative index and photosystem II operating efficiency of the leaf above the earleaf was measured in both populations. Several quantitative trait loci for the ratio vegetative index and photosystem II operating efficiency were discovered on chromosomes one, two, three, four, six, and nine. Select lines from the mapping populations were used in a North Carolina II experiment with the B73 backross lines used as females and the Mo17 backcross lines used as males. Backcross lines were selected based on close phenotypic resemblance to the recurrent parents and elevated levels of late-season ratio vegetative index. Hybrids synthesized from the backross lines exhibited higher ratio vegetative index values during the grain fill period than hybrids synthesized from Mo17 and B73. Photosystem II operating efficiency was positively correlated with grain yield across environments. A subset of the maize nested association mapping population that was crossed to PHZ51 was also analyzed for stay-green in four environments in 2010. Joint linkage mapping discovered four quantitative trait loci across the 23 recombinant inbred families for the stay-green trait. The quantitative trait loci were discovered in families with parents from both temperate and tropical germplasm pools of maize. The timing of senescence and the cause of stay-green in maize is still unclear. The maize mutant pre1 exhibits a premature senescent phenotype and could be important for understanding the senescence process. A bulk segregant analysis strategy was combined with array based genotyping and deep sequencing platforms to locate the loci responsible for the phenotype of pre1. Several candidate genes are hypothesized. The results of these studies suggest that genetic diversity for functional stay-green in maize exists in both the temperate and tropical germplasm pools. The diversity for this trait could be exploited for increasing abiotic stress tolerance in maize.^

]]> Michael Popelka Agriculture, Agronomy|Biology, Genetics|Agriculture, Plant Culture http://docs.lib.purdue.edu/dissertations/AAI3556569 http://docs.lib.purdue.edu/dissertations/AAI3556569 Wed, 22 May 2013 15:52:34 PDT In this work we describe two methods for detecting electron nematics in the high T_c cuprates. In addition we also provide a method to analyze the behavior of the local nematic and determine the model which describes the nematic ordering. The first method is a two step Monte Carlo process which models a nematic as an Ising spin with quenched random field disorder and the phase of a superconductor as an XY model which has local anisotropy in its bond with nearest neighbors (due to the presence of a local nematic). Using this method we make predictions about the noise and the effects of an orienting on the anisotropy of the london penetration depth. Our second method is to use anisotropy in the local Fourier Transform of an STM image to extract the direction of a local nematic. We can apply this method to all points in the image and use cluster analysis to extract critical exponents, which will allow us to determine the behavior of the nematic in the bulk of the material. Finally we describe future work which can be achieved with these methods. We find that the nematicity in one direction is inversely proportional to the square of the london penetration depth along that direction. From our second method we find that the nematicity of a sample of Dy doped BiSrCaCuO acts as though it is near the random field fixed point.^

]]> Benjamin Phillabaum Physics, General|Physics, Condensed Matter http://docs.lib.purdue.edu/dissertations/AAI3556565 http://docs.lib.purdue.edu/dissertations/AAI3556565 Wed, 22 May 2013 15:52:33 PDT The cytoskeleton represents a dynamic platform for detecting and reacting to a diverse collection of biotic and abiotic stimuli. It also comprises a network that is commonly hijacked by intracellular pathogens for their own purposes. As a result, the nature and timing of the changes in actin arrays range from an increase in filament abundance, to extensive bundling, to massive depolymerization, depending on the responding cell type and the nature of signal received. For example, following inoculation with symbiotic bacteria, the host actin cytoskeleton exhibits an increase in filament abundance, whereas infection with pathogenic fungi or oomycetes stimulates an increase in the extent of filament bundling. Many believe that these latter changes to actin filament architecture result from the physical penetration of cells by invading pathogens. Further, studies investigating the actin changes during bacterial pathogenesis, like Pseudomonas syringae infection, which does not penetrate cells, are lacking. Finally, the exact mechanisms used to produce changes in actin filament organization during plant infection are unknown; however, an increase in actin polymerization, a decrease in actin filament turnover, or a combination of the two may be involved. ^ As key signal transducers, numerous actin-binding proteins are known to regulate actin networks, and their response to the common second messengers associated with innate immunity is well characterized in vitro. One actin-binding protein family whose activities are regulated in vitro by pH changes, phospholipids, and protein phosphorylation is the actin depolymerizing factor (ADF)/cofilin family. ADF/cofilin contributes to stochastic filament severing and facilitates actin turnover. However, the actual mechanism of ADF-mediated turnover in cells has not been confirmed. We used powerful reverse-genetics approaches associated with the model organism Arabidopsis thaliana and state-of-the-art microscopy to investigate the loss of an ADF/cofilin isoform on actin filament dynamics in vivo. Epidermal cells from the adf4 homozygous mutant had up to a 3-fold reduction in severing frequency compared to wild-type, as well as increased filament lengths and lifetimes. Collectively, our findings are the first direct evidence for the importance of ADF/cofilin-mediated stochastic severing contributing to the disassembly of actin filament arrays in living cells. ^ We also investigated whether actin rearrangements in the plant host cytoskeleton occur following bacterial treatment using the Arabidopsis-Pseudomonas pathosystem. Using robust actin architecture analysis tools and spinning disk confocal microscopy, we quantified the temporal response of cotyledon epidermal cells to pathogenic and non-pathogenic P. syringae pv. tomato DC3000 strains. We measured an immediate but transient increase in actin filament abundance that was associated with innate immunity. Additionally, we used the genetics of both bacterium and plant to demonstrate that the increase in actin filament abundance still occurred in epidermal cells inoculated with non-pathogenic mutants deficient for type-III secretion or for all 28 putative effector proteins. Significantly, a similar actin response was elicited with treatments of bacterial and fungal microbe-associated molecular patterns (MAMPs). We also observed an increase in the extent of actin filament bundling at late timepoints, which appeared to be part of host-plant susceptibility. This is the first evidence that the host-cell cytoskeleton responds to multiple signals at different times following treatment with pathogenic bacteria. Finally, several Arabidopsis knockout mutants for a well-characterized MAMP receptor complex failed to elicit a change to actin arrays following DC3000 inoculation. Collectively, these results demonstrate unambiguously that the perception of MAMP ligands and receptor kinase signaling are necessary to trigger actin reorganization in host epidermal cells. ^ To further dissect the cellular mechanisms that underpin the increase in actin filament abundance during innate immunity, we utilized the Arabidopsis adf4 mutant and the high spatiotemporal resolution imaging of hypocotyl epidermal cells. If ADF4 activity is negatively regulated during innate immunity, we predict that the cytoskeleton in the adf4 knockout mutant will resemble the actin array changes observed during PTI. Furthermore, if ADF4 is a key player that contributes to the increase in actin filament abundance, the knockout mutant should be unresponsive to MAMP signals. The changes we observed following MAMP treatment were consistent with alterations to actin filament turnover and actin filament end dynamics. Indeed, several changes in stochastic dynamics properties phenocopied the features of the actin cytoskeleton in the adf4 mutant measured previously. Moreover, the adf4 mutant does not display changes in actin filament abundance following MAMP treatment. This provides compelling evidence that ADF4 activity is down regulated during PTI, and is the first data implicating a key actin-binding protein in the rapid actin turnover that occurs during plant innate immunity.^

]]> Jessica L Henty Biology, Botany|Biology, Cell|Agriculture, Plant Pathology http://docs.lib.purdue.edu/dissertations/AAI3556568 http://docs.lib.purdue.edu/dissertations/AAI3556568 Wed, 22 May 2013 15:52:33 PDT Periodic, clustered-dot halftone patterns generated by screening with a threshold matrix are generally considered to be the preferred choice for printing with electrophotographic printers. This approach has the dual advantage of yielding more stable printed patterns than aperiodic, dispersed-dot halftoning methods, and being very computationally efficient, since the halftoning is performed on a pixel-by-pixel basis with simple comparison operations. However, there is a tradeoff with periodic, clustered-dot halftones between using a coarser screen to yield more stable halftone patterns and using a finer screen to yield better rendering of detail. ^ Conventional way is to single halftone pattern in a document, but in this paper, we consider a dual-mode halftoning process that switches between periodic, clustered-dot screens of two different frequencies—a low frequency screen for smooth regions and a high frequency screen for detail regions. These regions are described by an object map that is extracted from a high-level representation of the page content to be rendered. This high-level representation is contained in the page description language (PDL) version of the page to be printed. ^ This idea is beneficial in that we can reduce printing artifacts at smooth region and fine rendition at detail region. Nonetheless, one drawback of dual-mode halftoning approaches is appearance of boundary artifacts at the boundary between the smooth and detail halftones. When switching between periodic, clustered-dot halftones with two different frequencies, we may have an appearance similar to the "jaggies" that occur along an edge in a sampled image. ^ To overcome the boundary artifact, our screens obey a harmonic relationship. In addition we implement a blending process based on a transition region. We propose a nonlinear blending process in which at each pixel, we choose the maximum of the two weighted halftones where weights vary according to the position in the transition region. Moreover, we describe an on-line tone-mapping for the boundary blending process, based on an off-line calibration procedure that effectively assures the desired tone values within the transition region. We will provide detail algorithm and experimental results for the dual-mode object oriented halftoning.^

]]> Seongjun Park Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI3556561 http://docs.lib.purdue.edu/dissertations/AAI3556561 Wed, 22 May 2013 15:52:32 PDT A novel technique for the microvortex flow in an opto-electrokinetic microfluidic platform is presented here. A moderately focused laser beam on a pair of indium tin oxide (ITO) electrodes produced two microvortices. This is a novel flow phenomenon consisting of twin opposing microvortices (TOMVs). The vortices contain a fast and strong jet flow region between them. The TOMV flow can be controlled and manipulated by non-uniform electric fields and optical illumination. The non-uniform electric fields were generated by a pair of ITO electrodes partially covered with a SU-8 film. The voltage and frequency of the applied AC signal was varied to study the effect on the flow. Optical illumination, from an infrared laser beam of 1064 nm was controlled by adjusting its power as well as its location relative to the electrodes. In situ generation and control of the TOMV flow allow it to be used as a micro-mixer or pump. ^ The TOMV flow depends on: (1) laser beam location on the electrode, (2) voltage, (3) frequency, and (4) laser beam power. The influence of each parameter was analyzed by micron-resolution particle image velocimetry (µPIV) technique. The location of the laser spot relative to the electrode changed causing the direction and pattern of the TOMV flow, to produce a symmetric, asymmetric or reversed flow, depending on the beam's location. The strength of the TOMV flow was linearly dependent on the voltage in the range between 3–9 Vp-p and laser power in the range between 0.2 to 1.0 W. Frequencies ranging from 3 kHz to 1 MHz can strongly influence the flow strength, in which its dependence follows the logarithmic-Gaussian curve showing the strongest flow at ∼ 107 kHz. The velocities along a cross-section as well as vortex trajectories were analyzed. The experiments presented herein provide practical guidance into applications of microfluidic manipulation in the field of biofluids and biological assay. ^ The previously described TOMV flows were generated mostly in suspensions of 1µm fluorescent polystyrene particles with a single laser beam. In order to investigate the underlying mechanism of the TOMV flow and its feasibility for manipulating various types of suspensions, suspensions of 2µm particles as well as milk emulsions were also used. The superposition of two TOMV flows was demonstrated with two laser beams. Our results demonstrate that this opto-electrokinetic technique has great potential for dynamically manipulating micro-fluid flows. ^

]]> Choongbae Park Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI3556559 http://docs.lib.purdue.edu/dissertations/AAI3556559 Wed, 22 May 2013 15:52:31 PDT Mass spectrometry has been widely proven as an invaluable tool for the field of complex mixture analysis and the identification of unknown molecules due to its high sensitivity, selectivity, versatility and speed. In addition, its reliability, reproducibility and its capability of providing information-rich data through the use of tandem mass spectrometric methodologies have revolutionized the analysis of complex mixtures. With the advent of atmospheric pressure ionization (API) techniques, mass spectrometry has transformed the way in which complex mixture analysis is performed, expanding the applications of MS to various nonvolatile and thermally labile substrates. In addition, the integration of tandem mass spectrometry (MSⁿ) experiments like collision-activated dissociation (CAD) and ion/molecule (I/M) reactions to most mass spectrometers has rendered these techniques as standards for the structural elucidation of components in complex mixtures. Also, API methods allow for the facile integration of MS with high-performance liquid chromatography (HPLC), thus allowing for the fast separation of these mixtures prior to tandem MS analysis. However, techniques such as this do not always result in the unambiguous identification of unknown components. ^ This thesis focuses on the development of ionization techniques, novel instrumentation, HPLC methods and tandem mass spectrometric methodologies to allow for the unambiguous identification of unknown compounds in complex mixtures. In addition, laser-induced acoustic desorption (LIAD) is investigated for its use with commercial mass spectrometers for the analysis of molecules currently not amenable to commercially available ionization techniques and instrumentation. Since the introduction of LIAD, it has been proven to be a powerful method for the evaporation of a wide variety of nonvolatile and thermally labile compounds, as well as complex mixtures wherein the composition is extremely varied. Finally, a novel and powerful mass spectrometer is proposed and described in this thesis. This instrument allows for CAD experiments and (I/M) reactions to be performed in tandem without their interference, thus resulting in one of the most versatile mass spectrometers to date. This instrument is likely to prove invaluable for the analysis of complex mixtures and the identification of unknown components in complex mixtures.^

]]> Benjamin C Owen Chemistry, Analytical http://docs.lib.purdue.edu/dissertations/AAI3556560 http://docs.lib.purdue.edu/dissertations/AAI3556560 Wed, 22 May 2013 15:52:31 PDT The dynamics of two coupled complex systems, one natural and another engineered, are examined regarding resilience. In this thesis, I explore several emergent phenomena which are generated by the coupling of complex systems, and argue that those are the signatures of change in resilience. The emergent phenomena include (1) functional homogenization, (2) fragmentation, and (3) stochastic tipping points. To this end, two types of coupling are recognized: (1) managed ecological systems which are extensively altered and intensively managed to meet human needs (e.g., agricultural landscapes, catchments with dams and levees); and (2) human-created engineered systems (e.g., infrastructure; cities, industrial districts). Both systems are subject to stochastic, natural disturbance regimes, and because of the emergent phenomena which imply inherent uncertainties in the dynamics of complex systems, conventional risk-based management approaches cannot be sufficient for designing and managing those systems. ^ Therefore, it is shown in this thesis that: (1) resilience of coupled complex systems is not a static property that a system has, but instead it emerges from what the system does in response to stochastic external disturbances and dynamics of internal coupled processes; and (2) stochastic, non-stationary tipping points emerge as a result of multiple types of stochastic forcing. Irreducible uncertainties and unexpected hazards are always present in complex systems. Thus, management of coupled complex engineered systems must be based on a recursive process that involves sensing, anticipating, adapting, and learning. Distributed control, anticipatory management, and organizational interaction strategies are also suggested as ways to be better prepared for unexpected shocks. ^ I suggest integration of risk- and resilience based management approaches that optimize resilience and efficiency for design and management of coupled complex engineered systems. Optimization goal is to minimize adverse impacts of unexpected shocks and surprises resulting from stochastic forcing, and to help expedite recovery. I use several case studies (2011 Fukushima Earthquake/ Tsunami; 2011 Mississippi River Flooding; 2010 Deep Water Oil rig Explosion; 2005 Katrina flooding of New Orleans; Long-term trends in wet deposition patterns in U.S. and East Asia) to examine each of these aspects of coupled complex system dynamics and resilience.^

]]> Jeryang Park Sustainability|Environmental Sciences|Engineering, System Science http://docs.lib.purdue.edu/dissertations/AAI3556557 http://docs.lib.purdue.edu/dissertations/AAI3556557 Wed, 22 May 2013 15:52:30 PDT Ambient ionization mass spectrometry has revolutionized the area of mass spectrometric analysis by allowing the analysis of organic and inorganic compounds in their native environment without sample preparation. Eliminating sample preparation has consequently reduced analysis time by several orders of magnitude compared to traditional mass spectrometry techniques such as those involving liquid and gas chromatography. This has been true especially in the analysis of plant materials, where extensive extraction and purification steps are typically required prior to mass analysis. Here we report on applications of different ambient ionization methods developed in our laboratory for direct analysis of biologically relevant compounds in plant materials. ^ The first part of this thesis discusses the use of the low temperature plasma (LTP) probe for qualitative analysis of extra virgin olive oil. Compounds which could be used to determine the authenticity of extra virgin olive oil such as free fatty acids and phenolic compounds were detected without the need for organic solvents or extraction processes. The second part of the thesis explores the direct analysis of chlorophyll catabolites in senescent plant tissues using desorption ionization (DESI) mass spectrometry. Non-fluorescent chlorophyll catabolites (NCCs), which are the final products of chlorophyll degradation, were detected and their molecular structures confirmed using tandem mass spectrometry (MS/MS) and reactive-DESI experiments. A novel imprinting method for imaging the spatial distribution of plant metabolites is described as well. Lastly, the relatively new paper spray ionization method was applied for direct analysis of polar lipids in green microalgae. A multi-step experimental protocol was employed to successfully characterize four classes of lipids in microalgae without the need for sample preparation. A novel approach for determining the position of unsaturation in olefins using reactive-paper spray ionization is described. Ozone produced in situ using simple low temperature plasma was used as the reagent molecule to cleave double bonds in the ions being analyzed by mass spectrometry.^

]]> Sheran A Oradu Chemistry, Analytical http://docs.lib.purdue.edu/dissertations/AAI3556558 http://docs.lib.purdue.edu/dissertations/AAI3556558 Wed, 22 May 2013 15:52:30 PDT This dissertation is comprised of seven essays that provide an economic perspective on Chinese food safety issues. This work explores various explanations for food safety problems in China ranging from structural reasons to problems found in the Chinese agricultural marketing system and provides an investigation into consumer and producer behavior. Due to the broad scope of this work, independence of research objectives, methodologies and data, each chapter of this dissertation is an independent essay. ^ The first essay provides an overview of the Chinese agricultural marketing system and explores food safety issues from a marketing utility perspective. The second essay focuses on measuring Chinese consumer preferences for select food safety attributes in the pork market. A choice experiment framework is used in conjunction with the use of random parameters and latent class models to estimate consumer demand heterogeneity for various product attributes. The third essay expands on this work and provides an alternative welfare measure allowing for the evaluation of aggregate market impacts of different food safety policies in China. The fourth essay provides an economic assessment of Chinese consumer preferences for food safety verification in one of the fastest growing food commodities in China, ultra-high temperature processed milk. ^ The fifth essay examines demand for Chinese food products abroad, by estimating American consumer preferences for imported aquaculture products within a country-of-origin and verification entity framework using a modeling framework that allow for correlated preferences. The sixth essay explores the effects of food safety media headlines on consumer demand for imported food products and its effect on demand for Chinese aquaculture products. ^ The final essay explores Chinese aquaculture producer behavior and their willingness to change and adopt certain production practices related to food safety and quality. Using an economic experiment, their preference for domestic versus foreign food safety inspection was assessed. The economic and food policy implications of all seven of these essays are discussed throughout this dissertation.^

]]> David Leonardo Ortega Economics, Agricultural http://docs.lib.purdue.edu/dissertations/AAI3556555 http://docs.lib.purdue.edu/dissertations/AAI3556555 Wed, 22 May 2013 15:52:29 PDT Metamaterials—artificially structured materials with engineered electromagnetic properties—have enabled unprecedented flexibility in manipulating electromagnetic waves and producing new functionalities. Metasurfaces are subwavelength thin metamaterial layers to introduce unusual properties do not exist in nature. They can play a fundamental role in generating synthetic scattering diagrams of macroscopic objects. Optical metamaterials and metasurfaces have enabled unprecedented flexibility in manipulating light waves and producing new functionalities. ^ We have studied various topics in this field, from designs to potential applications. We experimentally demonstrated the world's first optical metasurface which is capable of precisely manipulating light in arbitrary ways over a broad range of near-infrared light, which could make possible of many optical innovations such as more powerful microscopes, telecommunications and computers. We proposed the first hyperbolic metasurface, which consist of a highly anisotropic material layer and an isotropic material layer can support Dyakonov surface waves that have hyperbolic dispersion. This type of metasurfaces support a broadband singularity in the photonic density of states, which opens up another possibility to engineer the spontaneous emission efficiency. We also developed a set of parallel simulation tools which can handle a variety of problems in nanophotonics and plasmonics. Especially, we established an on-line research environment for the research community with six tools, which deliver a cloud computing service with no demand for either any powerful computational hardware or any additional software installations and cover a range of tasks including the design and simulation of complex transformation optics devices and optical metamaterials.^

]]> Xingjie Ni Physics, Electricity and Magnetism|Physics, Optics|Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI3556556 http://docs.lib.purdue.edu/dissertations/AAI3556556 Wed, 22 May 2013 15:52:29 PDT Calcium sulfate is typically added to ordinary portland cement (OPC) clinker during grinding to prevent flash set and to improve early-age strength development without causing volume instabilities. Recent changes to ASTM C150, Standard Specification for Portland Cement, have enabled greater flexibility in determining optimum sulfate levels in portland cement by not requiring ASTM C563, Approximation of Optimum SO₃ in Hydraulic Cement Using Compressive Strength, to be used in setting sulfate target levels. ASTM C563 requires strength testing using only the hydraulic cement, which is not always indicative of the optimum sulfate for field use, since supplementary materials (e.g., fly ash) may be used by the concrete producer. Adding additional sulfate to account for the sulfate demand of fly ashes can enable an improvement in the early age strength for cement-fly ash systems and decrease in problems that may be attributed to OPC-admixture-fly ash incompatibility such as abnormal setting and slow strength gain. ^ This thesis provides experimental data on the strength development and heat release during early hydration for cement-fly ash systems with different sulfate levels. The thesis focused on high calcium fly ashes, but low calcium fly ash was also tested. It is demonstrated that some fly ashes have their own sulfate demand and when these ashes are used in cement-fly ash blends there is effectively an increase in the optimal sulfate level that could be used for the OPC. It is also shown that optimum sulfate determined by heat of hydration measured with isothermal calorimetry is similar to the optimum sulfate determined by compressive strength at 1 day. Using isothermal calorimetry can result in substantial time and cost savings at plants for determining the optimal sulfate content. ^ Theories for the mechanisms that drive the differences in sulfate demand in OPC are reviewed. These theories are adapted for OPC-fly ash blends and are outlined, tested and discussed. The testing of the theories is done by characterization through isothermal calorimetry, semi-quantitative x-ray diffraction (XRD), and pore solution ion concentration. This provides data that can be used to evaluate the explanations of why some fly ashes influence optimum sulfate. ^ The fly ash C₃A and SO₃ have strong correlations to the increase in optimum sulfate along with freelime and soluble alkalis. The effect of the fly ash C₃A can be explained by the reactions that occur with sulfate to form ettringite or monosulfate, by the reaction with sulfate to form ettringite which contributes to strength at higher levels, or by retardation of the main alite hydration peak of the cement which requires additional sulfate to keep the sulfate depletion after the main alite hydration peak. The position of the sulfate depletion peak relative the main alite hydration peak has been correlated to optimum sulfate in the past and in this thesis. ^

]]> Mark D Niemuth Engineering, Civil|Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI3556554 http://docs.lib.purdue.edu/dissertations/AAI3556554 Wed, 22 May 2013 15:52:28 PDT Data outsourcing, also known as database-as-a-service, has been widely used in industry to provide better data management while lowering the cost. However data outsourcing is limited in the presence of sensitive data (e.g., medical records) due to the untrusted third party providing the data outsourcing service. In this thesis, we present a private data outsourcing model supporting both queries and updates by using anonymization. ^ Our private data outsourcing model is based on a data publishing technique called anatomization. Data are divided into identifying and sensitive data the same way in anatomization; however, the client can also reconstruct the original identifiable data from the separated data. Without the client, an adversary can link individuals to their actual sensitive values only to an extent specified by the underlying privacy preserving technique (such as k-anonymity or l-diversity). By exposing data where possible, the server can perform value-added services such as data analysis not possible with fully encrypted data, while still being unable to violate privacy constraints. ^ We first present a relational query processor limited to queries that minimize the client-side computation while ensuring that the server learns nothing violating the privacy constraints. We then focus on updates and present a dynamic private data outsourcing model on top of the query processor allowing the client to insert, delete and update tuples with the same privacy guarantees as our read-only model. Lastly, we present a prototype for our private data outsourcing model.^

]]> Ahmet Erhan Nergiz Computer Science http://docs.lib.purdue.edu/dissertations/AAI3556552 http://docs.lib.purdue.edu/dissertations/AAI3556552 Wed, 22 May 2013 15:52:27 PDT This study examines U.S. rhetoric and composition graduate faculty persons' views on collaboration--how they define, theorize, and practice this activity. This study introduces collaboration as a commonplace and as a differing cultural value in two divisions of the university, then in rhetoric and composition's history—before pointing to the need for an exigency-based study of collaboration. Two complementary protocols were used to collect data: an interview instrument with qualitative (narrative-seeking) questions for co-author pairs and an online survey with quantitative (bigger-picture) questions and options for explanation. The protocols are designed for replication or re-use by researchers in other sites, contexts, and disciplines. ^ The study's aggregated data show that the survey participants all use language—along a process-to-product continuum—to orient their view of co-authoring. Their theoretical bases for collaboration are singularly divergent, which further supports the consociation-exigency approach for studying collaborations by showing each collaboration as a unique event influenced by its actors and stemming from a kairotic exigency. The study examines the participants' diverse (and sometimes limited) agency in collaborating for their own research/career development, and their similar ideas about what it means to teach collaboration in the classroom, as well as looking at how collaboration is individually and institutionally valued within the sample. ^ In Chapter 4, a conceptual model, the Consociation-Exigency Model of Collaboration (CEMC), is posited as a potential tool for identifying and studying collaboration, according to its actors, influences, and exigency. Participants do exercise some agency in choosing and shaping how they collaborate, but several areas of external influences also bear on the shape of particular collaborations. ^ This conceptual model points researchers toward a flexible, data-driven framework, to account for the complexity of collaboration and acts of co-authoring. The model has potential for use in all fields of knowledge creation, should collaboration researchers repeat the protocols of the study and map collaborative events using spheres of influences (or consociations) and identifying where those influences converge to answer an exigency, resulting in a unique mode and outcome of the collaboration. ^ Armed with knowledge of a disciplinary view of collaboration and the conceptual model posited, researchers in rhetoric and composition, as well as in the humanities and science, may push forward in a search for new ways of extending knowledge through collaboration and co-authoring, as well as creating clearer rewards and necessary supports for those who engage in co-authoring for professional development and teaching in the Academy.^

]]> Margaret Shepard Morris Language, Rhetoric and Composition|Education, Higher http://docs.lib.purdue.edu/dissertations/AAI3556553 http://docs.lib.purdue.edu/dissertations/AAI3556553 Wed, 22 May 2013 15:52:27 PDT This thesis focuses on the derivation of improved computational schemes for the optimization of mixed integer programs (MIPs). These schemes are based on new theoretical results and are evaluated numerically to determine their practical usefulness. In this document, we first present the motivation for our research through practical examples. We then perform a literature review before formulating statements for the problems we propose to solve. Finally, we review the results we have obtained with respect to each of these research questions. ^ First, for improving the optimization of 0-1 MIPs we seek to derive new strong valid cutting planes for 0-1 MIPs through lifting techniques. In particular, we describe five families of strong inequalities for 0-1 MIP problems. We show that these inequalities can be applied to the simplex tableaux of the LP relaxations of 0-1 MIPs but also can be applied directly to their formulations. The separation of these cuts from simplex tableaux is immediate. The separation from the formulation is more difficult. We therefore propose several heuristics for it. We then present the results of a computational study comparing the performance of these cuts on a family of randomly generated problems and on instances from the MIPLIB 2003 library. ^ Second, we propose a new lifting scheme that yields strong valid inequalities for 0-1 MIPs. This scheme gives rise to inequalities that can be described in closed-form but is different from traditional superadditive lifting. A new family of inequalities is derived for MIPs using this approach. ^ Third, we propose a new paradigm for generating cuts for general MIPs that uses partial enumeration. A benefit of this approach is that new integer feasible solutions to the problem can be found during the cut generation process. We present computational results evaluating the effectiveness of this approach. ^ Fourth, we describe computational work that was done for improving SAS mixed integer linear programming solver. These include improvements to presolve, cuts and branching. ^ Finally, we conclude this thesis with a summary of research contributions and directions for future work.^

]]> Amar K Narisetty Operations Research http://docs.lib.purdue.edu/dissertations/AAI3556550 http://docs.lib.purdue.edu/dissertations/AAI3556550 Wed, 22 May 2013 15:52:26 PDT The current study focused on how six participants of a 2009 professional development activity at Yellowstone National Park described their experience and classroom instructional impact. The author focused on words and phrases illustrating perspective gathering, reflection and public performance to determine the impact of both the experience at Yellowstone National Park and the impact of that experience on the participants' classroom instructional practices. Using transcriptions of participants' reflective journals, semi-structure interview responses, as well as the author's hand-written observation journal notes, the author described a shared experience of the participants. The shared experience illustrated that there was evidence that the experience had an impact on the participants, but that there was very little evidence to show that there was any impact from the experience on the six teachers' classroom practices. The author described a number of limitations about the current study, as well as provided suggestions for future research that could overcome those limitations. These included strategies for collecting more data about the participants. Those data would reflect the reasons teachers choose to teach. In addition, the author suggested that data should be collected about the level of support teachers are provided by their school administration for making curricular decisions, the teacher's previous professional development experiences, and to determine the impact of statewide high stakes assessments on teacher instructional decision-making.^

]]> Christopher N McGrew Education, Teacher Training|Education, Secondary|Education, Social Sciences http://docs.lib.purdue.edu/dissertations/AAI3556551 http://docs.lib.purdue.edu/dissertations/AAI3556551 Wed, 22 May 2013 15:52:26 PDT The properties of polymer nanocomposites are significantly affected by Carbon Nanotube (CNT) dispersion. Even though dispersion is recognized by the scientific community as one of the main issues in nanocomposite synthesis, a method to characterize CNT dispersion has not yet been universally accepted. In the present work, a thorough and systematic approach to determine dispersion and characteristics of CNTs within a polyimide (PI) matrix and their effect on nanocomposite thermo-mechanical and electrical properties is presented. ^ CNT dispersion was characterized by voltage contrast scanning electron microscopy, applying high accelerating voltage to render images of the nanotube network embedded in the polyimide matrix and measuring CNT bundle diameter, contour length and end-to-end distance. Nanotube dispersion and characteristics were studied in nanocomposites synthesized with eight different sources of CNTs. CNT bundle aspect ratio—a quantitative measurement of dispersion—is found to decrease with increase in nanotube concentration for Single-Walled CNTs (SWNTs) synthesized via high pressure carbon monoxide process (HiPCO). The observed reduction of nanotube aspect ratio with concentration is modeled using the concept of percolation onset from percolation theory. ^ Multi-Walled CNTs (MWNTs) tend to form highly entangled CNT agglomerates instead of bundles and show worse distribution of CNTs within the PI matrix than HiPCO SWNTs. The distribution of polymer and CNTs is seen to worsen as CNT concentration increases, regardless of the source of CNTs used for composite synthesis. ^ The quality of nanotube dispersion is shown to explain the lack of expected increase in mechanical reinforcement in PI-CNT composites with concentration. Nanocomposites synthesized with HiPCO SWNTs show better dispersion characteristics and greater reinforcement than MWNT composites. A modified Cox micromechanical model that accounts for the actual change in nanotube bundle aspect ratio with concentration, nanotube waviness and orientation is able to predict the observed nanocomposite elastic modulus. CNTs characteristics are also a fundamental aspect of nanocomposite conductivity. The experimentally determined percolation threshold for CNTs-minimum concentration at which a conductive network is formed—is fairly predicted from CNT aspect ratio using percolation theory concepts, whereas the percolation exponent was found to be correlated with CNT length and waviness. ^ The analysis methodology and results presented in this work help explain property variability in polymer nanocomposites and establish a solid base for study and characterization of nanocomposites, which is essential for maximization of the potential of CNTs for polymer matrix improvement.^

]]> Carmen Rocio Misiego Arpa Chemistry, Polymer|Engineering, Chemical|Nanoscience http://docs.lib.purdue.edu/dissertations/AAI3556549 http://docs.lib.purdue.edu/dissertations/AAI3556549 Wed, 22 May 2013 15:52:25 PDT Renewable energy can offer cleaner sources of electricity, and photovoltaics have perhaps the greatest potential due to the large quantity of solar power that hits the earth's surface. However, the cost of electricity from photovoltaics is still too high. There are two paths for reducing this cost, the first being cheaper manufacturing. Our research group explores this option by looking at Cu₂ZnSn(S,Se)₄ (CZTSSe) thin film devices deposited by nanocrystal inks, which use earth abundant materials, and can be made using cheap deposition processes. The second path is increasing solar cell efficiency. We've explored this route using double-gyroid (DG) nanostructure devices that should be capable of multiple exciton generation (MEG), a kind of photophysics that allows for increased photocurrent and device efficiency. ^ Electrical characterization of our thin film devices shows a back contact barrier of 75 meV exists in our CIGSe device. CZTSSe devices have a defect level at 57 meV above its valence band, most likely due to a copper on zinc antisite. This defect acts as the main acceptor state. The device's series resistance increases drastically with decreasing temperature. Interestingly, this correlates with increasing photoluminescence at an energy of 1.5 eV, correlating with a trap state in the CdS layer of the device. These results suggest that the CdS layer could be the source of increasing series resistance with temperature. ^ With DG research, electrodeposited lead selenide was improved using new applied potential techniques and additives in solution, leading to less roughness and greater surface coverage. Bulk PbSe devices showed very nice diode behavior. CdSe and CdTe films were also electrodeposited, and films were improved by optimizing post-deposition techniques to make bulk CdTe devices with efficiencies over 4%. With DG films, an increased band gap was measured in DG PbS (0.11 eV increase) and CdSe films (0.05-0.14 eV increase), indicating quantum confinement. DG PbSe devices were electrodeposited by a number of techniques, but so far have shown only diode behavior and no photocurrent. ^ Concerned that recombination was limiting our devices, a new, fully analytic model was constructed that allows us to consider the effect of a wide range of parameters on nanostructured devices. A voltage-dependent photocurrent is calculated that accounts for charge transport by both drift and diffusion. The dark current accounts for bulk and interfacial Shockley-Read-Hall recombination. Our model suggests that DG devices will require low interfacial recombination velocities (<10⁴ cm/s). We also performed calculations using the detailed balance limit including a non-radiative recombination term. These calculations show that there is a significant shift in the ideal band gap for photovoltaics utilizing MEG. Even with a microsecond minority carrier lifetime, it shifts to 0.93 eV from 0.70 eV.^

]]> Robert F McCarthy Engineering, Chemical|Nanoscience|Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI3556365 http://docs.lib.purdue.edu/dissertations/AAI3556365 Wed, 22 May 2013 15:52:24 PDT In fluorescence microscopy, the accurate measurement of spatial closeness (colocalization) between two (or more) fluorescent labels each having a different wavelength, is a hotly disputed topic. The colocalization interpretation through image analysis-based techniques is often uncertain because image pairs are mostly analyzed based on a pixel-to-pixel comparison and the correlation between the images is usually taken as a measure of colocalization. Widely used colocalization measures such as Pearson's correlation coefficient (PCC), Mander's overlap coefficients (MOC), and intensity correlation quotient (ICQ) calculate colocalization by treating each pixel independently and therefore fail to determine whether the observed value occurred by chance and what will happen if two markers are not overlapping but still close enough to interact? Additionally, owing to the limited photon budget nature of fluorescence images, the correlation-based colocalization quantification is severely dependent on the image quality. To address this, we developed a robust methodology based on the doubly stochastic Gauss-Poisson Markov random field model for colocalization quantification. Our approach compares neighborhoods is defined by an Markov random field (MRF) and not by individual pixels; thereby giving accurate colocalization values even if the images are uncorrelated in strict mathematical sense. Our method partitions the pair of images to be tested for colocalization into statistically uniform segments (superpixels), the superpixels are subsequently treated as a realization of a doubly stochastic random field, and the parameters of the underlying random field are estimated for every superpixel. The estimated random fields are compared instead of pixels to measure the spatial overlap. The robustness of the proposed method to fluorescent surges make reliable colocalization measurements independent of illumination intensity and camera settings.^

]]> Awais Mansoor Biology, Biostatistics|Engineering, General|Engineering, Biomedical|Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI3556378 http://docs.lib.purdue.edu/dissertations/AAI3556378 Wed, 22 May 2013 15:52:24 PDT Activator protein 1 (AP-1) is a group of dimeric transcription factors composed of proteins including activating transcription factor 2 (ATF2), c-Jun and c-Fos. Increased cytoplasmic phosphorylated ATF2 was observed in prostate cancer compared to normal prostate suggesting that altered localization of ATF2 may contribute to the pathogenesis of the disease. On the other hand, the c-Jun downregulation was also observed in a fraction of advanced prostate cancer patients and in castration-resistant prostate cancer patients. The objective of the study was to elucidate the mechanisms regulating ATF2 nuclear-cytoplasmic shuttling and to characterize the role of AP-1 in prostate cancer. ^ In the first study, a novel chromosome region maintenance 1 (CRM1)-dependent nuclear export signal (NES) was identified in the most N-terminus of ATF2 (termed N-NES). Mutation of the hydrophobic residues in N-NES abrogated CRM1/N-NES interaction and increased nuclear localization of ATF2. Concomitantly, the transcriptional activity of ATF2 was enhanced following N-NES mutation. Therefore, the N-NES negatively regulates ATF2 nuclear localization and transcriptional activity. Mutation of both N-NES and a previously identified NES leaded to predominant nuclear localization, suggesting that both NESs function in cooperation to export ATF2 out of the nucleus. The function of N-NES was validated in various cell lines including prostate cancer cells. N-NES is unique in that it is only present in higher organisms and that it is also missed in certain splicing variants of human ATF2. ^ In a second study, I demonstrated that c-Jun functions as a potent inhibitor for androgen receptor (AR) in prostate cancer cells. Overexpression of c-Jun inhibits the activity of various androgen-responsive promoters. By generating LNCaP stable cell lines with inducible c-Jun expression, I showed that c-Jun downregulates transcripts of multiple AR target genes. Interestingly, long-term c-Jun overexpression also downregulated AR at both protein and mRNA levels, suggesting c-Jun suppresses AR signaling through a dual mechanism. Overexpression of c-Jun not only inhibits AR signaling but also cell proliferation of both hormone-naïve and castration-resistant prostate cancer cells. Molecular analysis reveals that c-Jun inhibits AR transactivation potential via an unknown target gene. These results suggest a novel mechanism by which c-Jun antagonizes the AR signaling. Future identification of the c-Jun target gene that mediates the AR inhibition will provide a new opportunity to develop novel therapeutics. ^

]]> Chih-Chao Hsu Biology, Cell|Chemistry, Biochemistry|Health Sciences, Oncology http://docs.lib.purdue.edu/dissertations/AAI3556364 http://docs.lib.purdue.edu/dissertations/AAI3556364 Wed, 22 May 2013 15:52:23 PDT The effect of liquid rheology on the flowfield resulting from non-Newtonian impinging jets was investigated experimentally and analytically. Experimental data were acquired using a unique experimental apparatus developed to examine the jet impingement of non-Newtonian liquids. The analytical modeling was aimed at determining which physical mechanisms transform non-Newtonian impinging jets into a sheet with waves on its surface, how those waves influence sheet fragmentation and subsequent ligament formation, and how those ligaments break up to form drops (primary atomization). ^ Prior to impinging jet measurements, the rheological properties of 0.5 wt.-% CMC-7HF, 1.4 wt.-% CMC-7MF, 0.8 wt.-% CMC-7MF, 0.06 wt.-% CMC-7MF 75 wt.-% glycerin, 1 wt.-% Kappa carrageenan, and 1 wt.-% Agar were determined through the use of rotational and capillary rheometers. Two approaches were used to experimentally measure solid-like gel propellant simulant static surface tension. All liquids exhibited pseudoplastic rheological behavior. ^ At various atomizer geometric and flow parameters sheet instability wavelength, sheet breakup length, ligament diameter, and drop sizes were measured from high-speed video images. Results showed that viscosity dependence on shear rate is not the sole factor that determines atomization likelihood. Instead, a key role is played by the interaction of the gelling agent with the solvent at the molecular level. ^ For instance, despite high jet exit velocities and varying atomizer geometric parameters HPC gel propellant simulants did not atomize. The molecular nature of HPC results in physical entanglement of polymer chains when gelled, which resists liquid breakup and subsequent spray formation. However, atomization was achieved with Agar, which absorbs the water and forms a network around it rather than bonding to it. ^ The measured liquid sheet instability wavelength, sheet breakup length, ligament diameter, and drop sizes were compared to predictions from a linear stability theory model, which employed the Bird-Carreau pseudoplastic rheology model and semi-empirical theories of sheet breakup length taken from the literature. Analytical results accurately predicted experiment data for all investigated formulations, with the exception of 1 wt.-% Agar. This is attributed to Agar's slightly different chemical molecular structure and its effect on resultant atomization. Overall, the linear stability theory developed here shows an improvement over previous linear stability theories which consistently over-predicted results.^

]]> Jennifer A Mallory Engineering, Aerospace|Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI3556363 http://docs.lib.purdue.edu/dissertations/AAI3556363 Wed, 22 May 2013 15:52:22 PDT Many pattern recognition applications rely on building decision making models based on meaningful and often hidden patterns of real world objects represented as points in a high dimensional feature space. Such a space presents great opportunities, as well as computational modeling hurdles that include the curse of dimensionality. Assumptions are often made, and more challenges encountered in easing the difficulty of analyzing and interpreting such data. The first step could be to assume that regular data information resides on a lower dimensional manifold. An immediate challenge is how to design mapping models such that the nonlinear relationships in observations are captured by Euclidean or non-Euclidean manifolds. Furthermore, can there be a general nonlinear embedding framework whose platform has functional properties for building new solutions to the problem of dimensionality reduction? To address these challenges, this thesis embarks on three fronts to provide and develop efficient nonlinear dimensionality algorithms by exploiting the regularity details within image scenes. First, it presents a non-Euclidean spherical stochastic neighbor embedding technique for the purposes of mapping data whose similarity spectrum suggests a nonzero negative eigenfraction. Secondly, the study presents a general framework based on the dynamic equations described by gradient potential fields. The framework incorporates a force field intuition to seek a minimum energy configuration state of a neighborhood graph. Thirdly, the platform is applied to propose novel unsupervised multidimensional artificial field embedding techniques that rely on the intuitive superposition of pair-dependent quadratic distance attraction and inverse-distance repulsion functions. The proposed models provide capabilities that preserve the local topology of data and establish significant discriminatory boundaries between different structures. Experimental investigations for visualization, gradient field trajectories, and semisupervised classification on remote sensing and computer vision images demonstrate the superiority of the proposed models over current state-of-art methods.^

]]> Wadzanai D Lunga Engineering, Computer|Engineering, Electronics and Electrical|Computer Science http://docs.lib.purdue.edu/dissertations/AAI3556362 http://docs.lib.purdue.edu/dissertations/AAI3556362 Wed, 22 May 2013 15:52:22 PDT Rapid advances in nanoscale integration and low power design techniques have resulted in a variety of highly miniaturized electronic systems for use in emerging application domains such as wireless sensor networks. Essential requirements for these systems include ultra-low cost, stringent size or volume constraints, long operation time and maintenance-free operation. A key challenge during the design and operation of these systems is the issue of conveniently and cost-effectively provide energy to these systems in order to sustain long-term operation. Conventional solutions based only on energy storage buffers, such as rechargeable batteries, cannot meet all of the above requirements. Micro-scale energy harvesting from the environment has the potential to satisfy all of these application requirements and, hence, is the focus of this research. ^ Even though there have been several micro-scale energy harvesting prototypes presented in literature, the design of efficient micro-scale energy harvesting systems has not yet been comprehensively studied. An efficient design implies rapid development time, low design effort, a cost-effective solution and optimal system performance. The design of efficient micro-scale energy harvesting systems requires an in-depth understanding of numerous design tradeoffs and considerations at all layers of design abstraction. This dissertation makes several contributions towards this. The first contribution is energy-efficient power converter circuit design using several new techniques in terms of circuit topology, transistor sizing and the number of stages. These optimization techniques reduce internal power loss, improve the power transfer capability, and hence boost the energy harvesting performance substantially. The second contribution is a new automatic maximum output power tracking method. The proposed technique consumes very little power, have a very low hardware cost, and has fast tracking speed. Therefore, it is well suited for micro-scale energy harvesting systems. The third contribution is based on the fact that currently, design of micro-scale energy harvesting systems depends heavily on designer's intuition and experience. Due to the lack of efficient design and simulation tools, current designs are mainly point solutions and no design methodologies exist for finding optimal design solutions. In order to overcome this challenge, a design framework that enables systematic design space exploration and quick performance evaluation of micro-scale energy harvesting systems at the early design phase is proposed. Unlike current design practices, which optimize each system building block in isolation, the proposed design framework supports cross-layer optimization of heterogeneous system buildings blocks. The proposed framework takes various design parameters into account, can accurately mimic system operation behavior and can evaluate the overall impact of various design parameters on the system. In addition to significantly reducing the design effort and enabling easy optimization of design parameters, the proposed framework also leads to a three orders of magnitude reduction in simulation time compared to low-level simulation tools. The accuracy and efficacy of the proposed framework are validated and demonstrated through multiple case studies.^

]]> Chao Lu Engineering, Computer|Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI3556361 http://docs.lib.purdue.edu/dissertations/AAI3556361 Wed, 22 May 2013 15:52:21 PDT This study examined the associations between mother-child conversations about past peer experiences and children's social skills. Specifically, three aspects of the conversation (i.e., maternal elaboration, emotion explanation, and social coaching) were used to predict children's social competence, physical aggression, and relational aggression. In addition, the study tested potential pathways to understand the associations between conversation characteristics and children's outcomes through social interaction knowledge (i.e., attribution bias and strategy knowledge). Finally, moderation hypotheses were explored to examine whether the associations between conversation and social skills differed depending on the quality of mother-child interaction style. Seventy-three mother-child dyads (children's mean age = 61.50 months) participated in the study. Mother-child interaction style was assessed through 15 minutes play session; the conversation characteristics were coded from mother-child reminiscing of three past events with peers in which the child felt happy, sad, and angry; children's social interaction knowledge was measured by child interview and enactive play; and children's social skills were reported by both mothers and teachers. The results showed that mothers' elaborative reminiscing style positively predicted social competence and negatively predicted physical aggression reported by both mothers and teachers. Furthermore, the study provided some evidence that the associations between conversation and child outcomes could be partially explained by children's strategy knowledge. Lastly, both conversation and mother-child interaction quality were important predictors of children's development of social skills. In some cases, conversation might serve as a protective factor that buffers the negative impact of poor interaction quality. ^

]]> Ting Lu Psychology, Social|Psychology, Developmental|Psychology, General|Sociology, Individual and Family Studies http://docs.lib.purdue.edu/dissertations/AAI3556359 http://docs.lib.purdue.edu/dissertations/AAI3556359 Wed, 22 May 2013 15:52:20 PDT Drawing from Multicultural Feminist Theory and Latino Critical Theory, this study examined how family-instilled values, culture, societal barriers, and workplace dynamics influence in Hispanic immigrant women's work experiences in the U.S. ^ This phenomenological study examined the work experiences of 28 Hispanic immigrant women, hourly workers, who were working in different industries including manufacturing, cleaning, food service, and care industry. This study was guided by a central question: What are the lived experiences of Hispanic immigrant women working in the U.S.? Data collection methods included semi-structured interviews and a focus group interview^

]]> Johana P Lopez Women's Studies|Business Administration, Management|Hispanic American Studies http://docs.lib.purdue.edu/dissertations/AAI3556360 http://docs.lib.purdue.edu/dissertations/AAI3556360 Wed, 22 May 2013 15:52:20 PDT We have developed a new pipeline for mapping dark matter associated with clusters of galaxies via weak gravitational lensing. This method will be useful both with current datasets and future large optical survey telescopes, such as the Large Synoptic Survey Telescope (LSST). We use a novel source finding technique using a wavelet detection method. We then find known photometric and spectroscopic redshifts associated with our sources and measure the ellipticities of galaxies using a second moment technique. The ellipticity and photometric redshift distribution are then converted to a dark matter map. We have represented the dark matter as smoothed particles to invert the ellipticity map. This had yielded both 2D and 3D dark matter distributions when applied to our Subaru archive image of Abell 2218.^

]]> Suzanne Lorenz Physics, Astrophysics http://docs.lib.purdue.edu/dissertations/AAI3556357 http://docs.lib.purdue.edu/dissertations/AAI3556357 Wed, 22 May 2013 15:52:19 PDT The Stochastic Hybrid System (SHS) is a class of complex stochastic dynamical systems with interacting continuous and discrete dynamics. Many cyber-physical systems with continuous/physical parts interconnected with discrete/logical elements can be well modeled as the SHS. This paper develops a set of theories and algorithms for state estimation and optimal control of the SHS. Firstly, to describe the time-evolution of the SHS, two kinds of dynamical models are proposed: the Discrete-Time SHS (DTSHS) and the Continuous-Time SHS (CTSHS). Then, a hybrid estimation algorithm is developed to estimate both the continuous and discrete states of the DTSHS with noisy sensor measurements. Also, the proposed hybrid estimation algorithm is applied to aircraft surveillance sensor fusion, aircraft trajectory prediction and conflict detection for air traffic management. As for the CTSHS, its state estimation problem is mathematically formulated and solved using proposed filtering equations which are able to characterize the time evolution of the probability distribution of the hybrid state estimates. The filtering equations are numerically solved via a Markov Chain (MC) approximation algorithm. It is proved that this algorithm is able to give a result that weakly converges to the exact solution of the filtering equation when the resolution of the approximation converges to zero. Finally, the optimal control problem for the DTSHS is solved via a "separable'' control scheme: the controller uses the proposed hybrid estimation algorithm to estimate the state of the DTSHS and the optimal control inputs are computed from the state estimates. To numerically compute the optimal mapping from the state estimates to the admissable control inputs, the Q-learning approach is applied, which is based on discretizing the distribution function space of all possible state estimates. The proposed optimal control algorithm is validated through a spacecraft rendezvous example. ^

]]> Weiyi Liu Engineering, Aerospace|Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI3556358 http://docs.lib.purdue.edu/dissertations/AAI3556358 Wed, 22 May 2013 15:52:19 PDT This is an evaluative research study of a NSF-funded, DRK-12 cyber-enabled teacher professional development program in elementary engineering education. The finding shows the significant impact of the program on students' science and engineering knowledge in the second year of the program's implementation. However, student learning gain varies significantly across teachers, and teacher social capital is positively associated with student learning achievement. The study uses social network analysis to analyze teacher social capital and visually represent it by teacher attributes such as schools, grades, cohorts, subgroups, and specific level of interaction. In addition, each teacher's social capital is calculated. The information from this formative evaluative research study provides the empirical evidence needed to recognize problematic areas and make recommendations for the program's improvement. Lessons learned from this program will also help other researchers who may want to follow or build upon what has already been done for future cyber-enabled teacher professional development in engineering education.^

]]> Wei Liu Education, Instructional Design|Education, Teacher Training http://docs.lib.purdue.edu/dissertations/AAI3556356 http://docs.lib.purdue.edu/dissertations/AAI3556356 Wed, 22 May 2013 15:52:18 PDT Cells are the basic building blocks for all organisms and multiply through cell division. In order to divide, one cell needs to duplicate its chromosomes and equally separate the duplicated chromosomes through a process called the cell cycle. This process has to be accurately regulated to maintain genome integrity, and dysregulation of cell cycle may result in severe diseases such as cancer. The research presented in this dissertation studies the role of Polo-like kinase 1 (Plk1), a critical regulator of cell division, and its implication for cancer therapy. G2 and S phase expressed protein 1 (GTSE-1), was identified as a substrate of Plk1, and characterized. Plk1-mediated phosphorylation of GTSE-1 was demonstrated to be essential for the inactivation of the tumor suppressor p53 during G2 DNA damage checkpoint recovery. To understand the role of Plk1 during tumorigenesis, a prostate cancer mouse model was used to show that knock-out of the tumor suppressor Pten can result in the elevated expression of Plk1. Plk1 is critical for Pten-depleted cells to adapt to the mitotic stress, characterized by chromosome misalignment phenotype. Another substrate of Plk1, Sgt1, was identified and characterized to illustrate how Plk1 promotes the kinetochore-microtubule attachment and thus to facilitate proper chromosome alignment. This study advances the knowledge of cell cycle regulation by Plk1, and demonstrates the facilitative role of Plk1 during tumorigenesis, providing a strategy to target Plk1 for cancer therapy.^

]]> Xiaoxiao Shawn Liu Biology, General|Biology, Cell|Chemistry, Biochemistry|Health Sciences, Oncology http://docs.lib.purdue.edu/dissertations/AAI3556354 http://docs.lib.purdue.edu/dissertations/AAI3556354 Wed, 22 May 2013 15:52:17 PDT Scatterhoarding animals play a key role in the dispersal and reproduction of commercially and ecologically important tree species throughout the world. In particular, seed caching by animals such as tree squirrels (Sciurus ) and jays (Corvidae) is largely responsible for natural regeneration in eastern North American oaks (Quercus). In this dissertation, I explore the roles of seed traits, animal traits, and ecological context in determining how animals handle seeds, and how these handling decisions affect seed fate. I also develop new statistical approaches to the analysis of seed tracking data. Chapter 1 introduces the issue of context-dependent acorn dispersal from both a theoretical and applied perspective. Chapter 2 synthesizes the literature on scatterhoarding behavior under a utility-based choice modeling framework to develop a general model of hoarder decision-making. Chapters 3 and 4, respectively, use expectation-maximization (EM) techniques to derive an estimator for dispersal and survival of marked seeds with imperfect detection, and then apply this estimator to determine the effects of change in seed community composition on seed fate in northern red oak ( Q. rubra), white oak (Q. alba), and American chestnut (Castanea dentata) dispersed by forest rodents. Chapter 5 uses data on radio tagged northern pin oak (Q. palustris), black oak (Q. velutina), and white oak dispersed by blue jays (Cyanocitta cristata), tufted titmice (Baeolophus bicolor) and other birds to examine the effects of habitat on seed movement and survival. Finally, Chapter 6 proposes a hidden Markov model designed to analyze spatially explicit multistate mark-recapture data on tagged seeds. ^

]]> Nathanael Issac Lichti Biology, Biostatistics|Biology, Ecology|Psychology, Behavioral Sciences http://docs.lib.purdue.edu/dissertations/AAI3556355 http://docs.lib.purdue.edu/dissertations/AAI3556355 Wed, 22 May 2013 15:52:17 PDT Powdered ingredients and products are commonly used in the food and pharmaceutical industry. The stability of these powders may be affected by a variety of conditions, including temperature, relative humidity (RH), light, oxygen, pH, and particle size. Premixes are often used in a manufacturing setting, and blended systems are less stable than their individual counterparts. Water is ubiquitous to the environment and can have an impact on both the chemical and physical stability of powder systems. Deliquescence is a first order phase transformation from solid to liquid state that occurs at a specific RH for various water soluble crystalline solids. Current research indicates that the onset of deliquescence leads to instability for a variety of individual powders and blends. Understanding how the environmental and formulations factors influence the deliquescence for powder systems is important for quality control. ^ The general scope of this study was to (1) determine the effect of anticaking agents on the chemical stability, moisture sorption, and deliquescence RH for crystalline solids and blends; (2) determine the effect of initial moisture content and RH cycling on the chemical stability and color change of vitamin C; and (3) determine the relationship between temperature, solubility, and heat of solution on the onset deliquescence RH for individual ingredients and blends of deliquescent solids. All deliquescent ingredients were affected by the addition of anticaking agents over time, including vitamin C, sodium chloride, sucrose, fructose, and citric acid. RH cycling led to minimal changes in chemical stability. Changes in initial moisture content in vitamin C samples led to minimal amounts of chemical degradation in concentrated systems and complete instability in dilute solutions, while color change occurred at a faster rate than chemical degradation. In addition, mathematical models were utilized for complex blends of deliquescent ingredients to predict the deliquescence RH based upon temperature, solubility, and heat of solution. In conclusion, numerous factors affect deliquescence, leading to enhanced moisture sensitivity and reduced chemical and physical stability of powder blends. Careful consideration should be made when formulating powder blends and determining proper storage conditions to optimized product quality and enhance powder shelf-life.^

]]> Rebecca A Lipasek Agriculture, Food Science and Technology http://docs.lib.purdue.edu/dissertations/AAI3556342 http://docs.lib.purdue.edu/dissertations/AAI3556342 Wed, 22 May 2013 15:52:16 PDT Warm laser shock peening (WLSP) is a thermal-mechanical processing technique, which integrates the advantages of laser shock peening (LSP), dynamic strain aging (DSA), and dynamic precipitation (DP) to enhance the fatigue performance. Compared with LSP, WLSP results in a better stability of microstructures and mechanical properties due to the dislocation pinning effect of nano-precipitates. However, the efficiency of WLSP on mechanical performance is relatively low, and the microstructure after WLSP is not optimized. ^ In this study, thermal engineered LSP is proposed and evaluated in order to obtain the optimal microstructures with the optimized pinning strength for mechanical applications. This technique extends the precipitation kinetics from the nucleation stage to the coarsening stage by combining WLSP with a following post-shock heat treatment. Experimentally, AISI 4140 steel and aluminum alloy 6061 (AA6061) have been selected as the materials to conduct thermal engineered LSP; the optimal mechanical properties, including the surface hardness, the stability of surface strength, the stability of compressive residual stress, and the bending fatigue performance have been obtained by carefully manipulating processing conditions; the resulting microstructures after various processing conditions have been characterized by TEM. The mechanism of the extended fatigue performance after thermal engineered LSP has been theoretically investigated; an analytical model has been proposed to estimate the nucleation rate during processing; multiscale discrete dislocation dynamics (MDDD) simulation has been conducted to investigate the interaction of dislocations and precipitates during the shock wave propagation. Through this study, it has been found that: (1) after WLSP, the unique microstructures with highly dense nano-precipitates surrounded by highly dense dislocations is generated; (2) during post-shock heat treatment, the coarsening of precipitates is dislocation-assisted, and the growth of precipitate size is accompanied with the decrease of precipitate number density; (3) the dislocation pinning effect makes the major contribution to the enhanced mechanical properties and microstructure stability after processing, and the pinning strength is highly dependent on the precipitate parameters, including the size, number density, distribution, and volume fraction; (4) by carefully adjusting the processing condition (including WLSP laser intensity and temperature, and post-shock heating temperature and time), the optimal microstructure for optimal mechanical properties of metallic components could be obtained.^

]]> Yiliang Liao Engineering, General|Engineering, Industrial http://docs.lib.purdue.edu/dissertations/AAI3556343 http://docs.lib.purdue.edu/dissertations/AAI3556343 Wed, 22 May 2013 15:52:16 PDT Failure initiation of carbon fiber reinforced polymer matrix composites and the uncertainty measurement of the model used to predict this phenomenon are the central topics in this work. ^ To begin, an open hole off axis specimen in tension was modeled with finite element software. The FE model replicated the geometry, material properties and boundary conditions of tests performed on real composite coupons so that experimental data were available to compare to model predictions. The coupon was not modeled explicitly, i.e., it was not represented with the fibers embedded in the matrix. Instead, it was modeled as a monolithic material with homogeneous mechanical properties. The resultant average strain field in the homogeneous coupon in tension was de-homogenized with the MME so that the average strain fields were localized. The volumetric and deviatoric strain invariants were calculated following the de-homogenization or enhancement. De-homogenization was taken one step further: randomness in fiber distribution was considered in order to model the dispersion of the fibers in the composite. The implementation of random fiber distribution aimed to replicate the variability in mechanical properties and mechanical behavior that characterizes the composite. With the strain invariants calculated after consideration of fiber distribution randomness, locations with high values of strain invariants were identified with contour plots of the coupon. The largest values of strain invariants were located at the hole surface in a very specific interval. Thousands of simulations with the post-processing of FE data allowed the definition of a failure angle distribution that agreed well with the experiments in as much as 75%. ^ An investigation on the capability of SIFT and MME when they were used to predict failure initiation and failure location in the open hole off axis coupon was carried out. Predictions' validation of the failure angle interval was performed with the use of Bayesian methods. Bayesian approaches' core characteristic is that they allow update of existent data's statistics as new data arise. The resource used is known as the Bayes' factor. We consider the experimental data as the existent data. Model predictions were considered as the update to the experiments. The Bayes' metric calculated from model predictions and experimental data gave a good indication that the experiments support the predictions performed with the model. ^ Finally, a more general validation of SIFT and MME was elaborated using also the Bayes' factor. In this case, 9-fibers finite element models were used to represent explicitly the composite material. These simulations were taken as a representation of experimental data. A unidirectional tensile deformation was applied to the 3-cells by 3-cells model and the resulting strains were used directly to calculate the strain invariant at failure with no use of MME, since the model represented explicitly the material. The MME method was also applied by finding the dependency of the deviatoric strain invariant with the fiber volume fraction randomness and with the applied strain, including the effect of thermomechanical strains. Thermoresidual strains were found to cause non-linear response of the deviatoric strain invariant. Specifically, a quadratic relationship was found between the invariant and the volume fraction that corresponded to the value of the applied strain in tension simulated with the explicit FE model. This quadratic relationship was evaluated thousands of times with the random generated volume fraction distribution. Hence, the random volume fraction distribution generated a random strain invariant distribution. Validation of this new data calculated with MME was performed similarly to the case of the open hole geometry. In this case, the deviatoric strain invariant distribution derived from the explicit finite element model was taken as the existent data, the experimental data. The distribution calculated with MME for the thousands of realizations with the quadratic relationship was considered the update to the experiments. The Bayes' factor was calculated by proceeding similarly as before. Once more, the Bayes' metric gave an indication of the high reliability attainable when SIFT-MME is used to predict composite failure initiation. (Abstract shortened by UMI.)^

]]> Alvaro Jesus Mendoza-Jasso Engineering, Mechanical|Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI3556341 http://docs.lib.purdue.edu/dissertations/AAI3556341 Wed, 22 May 2013 15:52:15 PDT This dissertation focuses on the transport aspect of graphene nanoribbons and high-transition temperature superconductors (HTSC). Concerning graphene, we propose a nano Peltier cooling device using a single graphene nanoribbon. Based on the membrane-like features of graphene, its cooling power can be tuned after fabrication by applying uniaxial pressure. We estimate the cooling power using two different methods and find that it is close to that achievable with the best cooling devices. In HTSC, we study the transport noise and vortex dynamics in the pseudogap regime. The equilibrium noise power spectrum of the magnetization in two-dimensional Random Field Ising Model (2D RFIM) is studied such that a crossover temperature is identified. Spin configurations in 2D RFIM are further mapped into resistance networks to study the behavior of transport noise in the local nematic phase. Our results are qualitatively consistent with recent observations in YBCO experiments. Vortex dynamics in extremely type II superconductor is studied using modified Coulomb gas model. Nernst signals and diamagnetism in the vortex smectic phase is estimated. Our results serve as a probe for experimentally detecting the vortex smectic phase, which is theoretically predicted in 2003 by Carlson, et al.^

]]> Wan-Ju Li Physics, General|Physics, Condensed Matter|Physics, Theory http://docs.lib.purdue.edu/dissertations/AAI3556340 http://docs.lib.purdue.edu/dissertations/AAI3556340 Wed, 22 May 2013 15:52:15 PDT In the first part of this dissertation, we present the first experimental validation process of EMM for measuring the performance-based flexure width of a pair of MEMS devices through capacitance sensing. We define the performance-based flexure width as the width that the model must have such that the performance of the model matches the performance of the true device. We validate EMM’s practicality, precision, repeatability, and ability to create experimentally accurate models. ^ We create the first EMM test and validation process. The capacitance measurement uncertainty of our capacitance metering system is about 20 aF. Our present design and equipment prototype setup yields a width measurement uncertainty on the order of 1nm, which is about an order of magnitude better than what we are able to achieve using SEM. The ultimate of EMM uncertainty has yet to be explored. EMM theory suggests that uncertainty can be further improved by increasing deflection, improving the precision of applied voltage, reducing parasitic capacitance, improving the precision of capacitance, reducing the overall size of the device, or optimizing the design parameters. ^ Our validation procedure includes using the conventional SEM to visually measure the width of flexures having coarse sidewalls at various axial locations. Human error and subjectivity are associated with each SEM measurement in determining the edge location of the coarse sidewalls. In fact, every time SEM measurements are made, the result varies. SEM measurements are good for inspecting local geometry details. However, SEM cannot be used to measure the performance-based width. That is, the average width obtained by SEM cannot be used for bending models because stiffness is nonlinear in width. Moreover, width varies along the thickness of the flexure, which cannot be measured by SEM. Since there are no standards for measuring width and since SEM does not provide complete validation, we instead use SEM as a bounding validation method. That is, the direction and magnitude of the measurements are comparable. For example, if the width measured by SEM is larger than layout width, then the performance-based width measured by EMM is larger as well, and about the same order of magnitude. In addition, the performance-based width measured by EMM lies within the estimated bounded range of minimum and maximum width measured by SEM. ^ In the second part of this dissertation, we modify the original EMM theory for geometry from measuring flexure width (EMM1) to measuring gap stop (EMM2). We present the first experimental validation process of EMM2. Compared to EMM1, EMM2 reduces the number of devices to one, reduces thermal vibrations through contact, and eliminates the sensitivities to non-ideal geometries and compliant bulk material. Our results validate the EMM2 in terms of its practicality, precision, and repeatability, and also suggest its accuracy though bounding analysis from SEM measurements. ^ The capacitance measurement uncertainties of the probing and wire bonding capacitance metering systems are about 20aF and 80 aF, respectively. With our current design and system configuration, we achieve a gap measurement uncertainty on the order of 1nm and 10nm, respectively. Our results are better than what we were able to achieve using our available SEM. The ultimate of EMM2 uncertainty has yet to be explored. EMM2 theory suggests that uncertainty can be further improved by reducing parasitic capacitance, improving the precision of capacitance, or optimizing design parameters. ^ In the third part of this dissertation, we present how to extend the results of EMM2 measurements of gap to immediately extract measurements of displacement, force, and stiffness without any further calibration efforts. Measurements of displacement, force, and stiffness are based on accepted first principles: the comb drive’s linear relationship between capacitance and displacement, the relationship between stored potential energy and electrostatic force, and the linear force-displacement for folded flexure with small deflection. Our results validate EMM2’s practicality, precision, and repeatability for measuring displacement, force, and stiffness, and also suggest its ability to create experimentally accurate models. (Abstract shortened by UMI.)^

]]> Fengyuan Li Engineering, Electronics and Electrical|Engineering, Mechanical|Nanotechnology http://docs.lib.purdue.edu/dissertations/AAI3556339 http://docs.lib.purdue.edu/dissertations/AAI3556339 Wed, 22 May 2013 15:52:14 PDT Solid state amorphization, and in particular crystalline to amorphous transformation, can be observed in metallic alloys, semiconductors, intermetallics, minerals, and also molecular crystals when they undergo irradiation, hydrogen gas dissolution, thermal interdiffusion, mechanical alloying, or mechanical milling. Although the amorphization mechanisms may be different, the transformation occurs due to the high level of disorder introduced into the material. Milling induced solid state amorphization is proposed to be the result of accumulation of crystal defects, specifically dislocations, as the material is subjected to large deformations during the high energy process. Thus, understanding the deformation mechanisms of crystalline materials will be the first step in studying solid state amorphization in crystalline materials, which not only has scientific contributions, but also technical consequences. ^ A phase field dislocation dynamics (PFDD) approach is employed in this work to simulate plastic deformation of molecular crystals. This PFDD model has the advantage of tracking all of the dislocations in a material simultaneously. The model takes into account the elastic interaction between dislocations, the lattice resistance to dislocation motion, and the elastic interaction of dislocations with an external stress field. The PFDD model is employed to describe the deformation of molecular crystals with pharmaceutical applications, namely, single crystal sucrose, acetaminophen, γ-indomethacin, and aspirin. Stress-strain curves are produced that result in expected anisotropic material response due to the activation of different slip systems and yield stresses that agree well with those from experiments. The PFDD model is coupled to a phase transformation model to study the relation between plastic deformation and the solid state amorphization of crystals that undergo milling. This model predicts the amorphous volume fraction in excellent agreement with experimental observation. Finally, we incorporate the effect of stress free surfaces to model the behavior of dislocations close to these surfaces and in the presence of voids.^

]]> Lei Lei Engineering, Mechanical|Health Sciences, Pharmacy|Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI3556338 http://docs.lib.purdue.edu/dissertations/AAI3556338 Wed, 22 May 2013 15:52:13 PDT The occurrence of endocrine disrupting chemicals (EDCs) in concentrated animal feed operation (CAFO) waste, and the potential effects of these chemicals on aquatic ecosystems have been of recent concern, especially in large agricultural regions. The waste from CAFOs is often applied as efficient fertilizer to nearby agricultural fields, resulting in the runoff of hormones, pesticides, and nutrients into adjacent aquatic systems. There is a lack of research on the potential impacts of this runoff on fish in these systems, as well as a lack of tools available to use in investigating these impacts on early life stage fish. We utilized field and laboratory studies to investigate CAFO associated mixtures of chemicals on fish. We also characterized baseline expression of genes involved in sex differentiation in fathead minnows (Pimephales promales) to be used in assessing endocrine disruption during development. ^ A field study was conducted in which fish community structure, reproductive condition, and growth were assessed in aquatic ditches adjacent to agricultural fields land-applied with CAFO waste. Fish species richness and index of biodiversity were significantly lower in these ditches compared to those in a reference creek with no CAFO impacts. We also found fish in the CAFO ditches had faster somatic growth than those in the reference creek. An in situ exposure of CAFO-impacted ditchwater was conducted on fathead minnows from embryos (< 24 h post fertilization, hpf) to 45 d post hatch (dph). These fish show significantly skew sex ratio toward males (60%) compared to those in a control group (49%). These fish also were significantly larger. ^ Using a new technique to identify sex in early life stages, a study was conducted to evaluate sex-specific gene expression changes throughout development in fathead minnows for the first time. Six genes involved in sex differentiation and gonadal development were evaluated including: dmrt1, cyp19a, cyp17, star, esr1, ar. These data were used as baseline information to assess sex-specific changes in gene expression after exposure (5 ng/L) to a synthetic estrogen (17α-ethinylestradiol) and a synthetic androgen (17β-trenbolone) during a sensitive time in development (10–20 dph). Mostly, those genes upstream in the steroidogenesis process were effected (cyp17 and star), and esr1 was an indicator estrogen exposure. Similar patterns of expression changes were seen in an exposure of fathead minnows from embryo (< 24 hpf) to 20 dph to a mixture of chemicals in a laboratory setting similar to those found at CAFO impacted sites. Juveniles from this laboratory study of CAFO chemical mixture sampled at 45 dph did not have an altered sex ratio, but the majority of males in the exposure group did have the presence of ovarian cavities (not present in the control males) indicating a feminizing effect from this exposure. ^ In conclusion, our results indicate that the fish community at a reference stream was more diverse compared to CAFO impacted sites. There was also evidence of faster somatic growth in fish at the CAFO sites, and there were indications they may be investing less in reproductive growth. We observed signs of endocrine disruption in both laboratory and in situ exposures to CAFO associated mixtures of chemicals (i.e. decreased resproductive conditions, increased growth, and gene expression changes). However, the results of these studies show contrasting effects, demonstrating the sensitivity of endocrine effects to differences in overall composition of estrogen and androgen concentrations in these mixtures. We were able to use a new molecular sex marker to establish the first sex-specific baseline expression of a small suit of genes involved in sex differentiation in fathead minnow. This tool was further utilized to assess sex-specific gene expression changes in response to hormone exposure in early life stage fathead minnows. These baseline data allowed us to further confirm the estrogenic effect of the CAFO chemical mixture used in our laboratory exposure study. The studies presented here can serve as a starting point to gain a better understanding of how CAFO associated hormones and chemical mixtures impact endocrine function in fish during development.^

]]> Jessica K Leet Health Sciences, Toxicology|Biology, Endocrinology|Agriculture, Fisheries and Aquaculture http://docs.lib.purdue.edu/dissertations/AAI3556337 http://docs.lib.purdue.edu/dissertations/AAI3556337 Wed, 22 May 2013 15:52:13 PDT As today's distributed applications increase in complexity, it becomes increasingly difficult to detect errors and performance anomalies in these applications. In addition, some faults only manifest when the application is deployed at large scale. Most of the existing debugging tools scale poorly and do not automate the process of finding the origin of failures. Although it is desirable to automatically predict impending failures, most of the existing error detection approaches do not predict failures. T^ his dissertation proposes scalable techniques for error detection, problem localization, and failure prediction for distributed applications. First, an error detection and diagnosis technique for scientific applications is presented. The technique summarizes historic control-flow and timing information of MPI tasks using semi-Markov models. When a failure occurs, it leverages the models to determine the parallel task(s) and code region(s) where a fault is first manifested. The isolation of a difficult-to-catch bug in a large scale molecular dynamics simulation code and fault injections demonstrate the effectiveness of the technique. Second, frameworks for problem localization and failure-prediction for commercial distributed applications are proposed. The frameworks learn application's normal behavior by monitoring multiple performance metrics. They then infer normal correlations between the metrics to pinpoint the suspicious metric(s) and code region(s) where faults are manifested. Using time-series models, the frameworks can predict impending failures with up to 15-51 minutes in advance. The frameworks are demonstrated with bug cases in Apache Hadoop, HBase, Android OS, and a campus-wide Java EE application. ^

]]> Ignacio Laguna Peralta Engineering, Computer|Computer Science http://docs.lib.purdue.edu/dissertations/AAI3556335 http://docs.lib.purdue.edu/dissertations/AAI3556335 Wed, 22 May 2013 15:52:12 PDT A growing body of research in the past two decades has focused on the development of pragmatics in children with specific language impairment (SLI). This population has been shown to experience difficulty with social interaction compared to their typically-developing peers. However, research has not conclusively established whether this is due to an actual deficit in conversational pragmatics, or whether their difficulty with expressive and/or receptive language disrupts their ability to interact appropriately in social settings. ^ This study employed two experimental tasks to test the ability of children with SLI to extrapolate information not explicitly stated to interpret the meaning of an utterance. To avoid the potential confounding effect of increasing both grammatical complexity and the complexity of contextual processing, the complexity of contextual processing was held constant while grammatical complexity was varied independently. ^ Eleven children with SLI, aged 49-69 months, were asked questions about situations portrayed in pictures and short puppet shows; responding appropriately to these questions required participants to extrapolate information not explicitly stated but available based on contextual cues. Some stimulus items were presented using low grammatical complexity (active construction) and some using high complexity (passive construction). The responses of the children with SLI were compared to those of children in two control groups. The first control group consisted of 10 children with typically developing language skills matched for age (48-69 months); the second consisted of seven younger (age 36-46 months) children with typically developing language. ^ Results of the study did not conclusively support or refute the hypothesis that pragmatic competence is linked to linguistic development rather than general cognitive maturation. Children with SLI performed with lower accuracy than their typically developing peers on tasks involving both low and high grammatical complexity. However, their response patterns were dissimilar similar to the younger control group of typically developing children matched for language level. ^ These findings suggest that children with SLI may possess age-appropriate pragmatic skills, but experience difficulty applying these skills in situations requiring them to do so while simultaneously processing linguistic information, either expressively or receptively.^

]]> Robert M Kurtz Language, Linguistics|Health Sciences, Speech Pathology http://docs.lib.purdue.edu/dissertations/AAI3556333 http://docs.lib.purdue.edu/dissertations/AAI3556333 Wed, 22 May 2013 15:52:11 PDT A series of poultry studies was conducted to confirm the possible variation in ileal AA digestibility between species as well as estimation methods used. In the first study, the apparent ileal AA digestibility of 6 feedstuffs including corn, wheat, DDGS, CM, SBM, and MBM were determined for White Pekin ducks in a 5-d experiment. There were considerable differences among feedstuffs in the digestibility of their AA for ducks, which indicated that digestible AA rather than total AA contents in the feedstuffs are more relevant measurements to describe bioavailable AA contents for poultry. The second study was conducted to determine response in digestibility of DM and the AA composition of ileal endogenous flow of 26-d-old broilers to NFD formulated with different ratios of corn starch to dextrose. The results showed that the ratio of corn starch to dextrose in a NFD may affect estimates of ileal endogenous flows of N and AA. Thirdly, broiler chickens and White Pekin ducks were used in a 5-d trial to test additivity of the AID and SID of AA in corn and SBM. The results indicated that AID of some AA for corn and SBM were not additive in the mixed diet but SID values were additive irrespective of the ingredients and species used. ^ The next study was conducted to compare ileal AA digestibility of SBM and CM for broilers and ducks using the regression method based on apparent or standardized ileal AA digestibility. The results of this study showed that ducks have higher basal endogenous AA losses compared with broiler chickens as well as higher ileal AA digestibility estimates derived from the SID-based regression approach indicating that broiler ileal AA digestibility values should not be used in formulating duck diets. Lastly, two studies were conducted to investigate efficacy of exogenous enzymes including phytase and β-mannanase on nutrient digestibility. The results from these studies showed that phytase supplementation improved protein efficiency ratio of broilers fed diets containing CM as the sole protein source but did not affect the ileal digestibility of AA in CM determined by the regression method. The results also indicated that supplementing β-mannanase may improve gain and energy utilization of broilers whereas it may not affect ileal AA digestibility. In conclusion, the overall results from these studies showed that there are considerable variations in digestibility of AA between feedstuffs, species, and estimation methods and that SID corrected for basal endogenous AA losses determined by a standard NFD method should be considered as a reliable measurement. In addition, the results indicated that ileal AA digestibility determined with broilers should not be used for formulation of duck diets.^

]]> Changsu Kong Agriculture, Animal Culture and Nutrition http://docs.lib.purdue.edu/dissertations/AAI3556334 http://docs.lib.purdue.edu/dissertations/AAI3556334 Wed, 22 May 2013 15:52:11 PDT This dissertation consists of three essays on the public goods game. Each essay is an experimental examination of the game and investigates whether behavior in the lab environment is affected by changes to the basic structure of the game. ^ The first essay investigates if differences in information within a group impacts behavior. In each group there are two subject types, a manager who observes the individual contribution choices of each group member and donors who can only view the total amount contributed. The difference in information does not lead to a significant difference in average contributions for the two types. It is suggested that no effect is found because both information sets allow subjects to compute the average contributions of others. ^ The second essay investigates how agency problems at public goods producers, such as non-profit organizations, impact the voluntary provision of public goods. One subject is assigned as the manager, as in the first essay, but in certain treatments the manager is given the ability to exploit the contributions of others. These managers often take advantage of the opportunity to exploit the contributions of others but do so strategically. This strategic behavior reduces the impact of a change in the marginal per capita return and results in contribution behavior that is no longer conditional on the behavior of others. Interestingly, there is little effect on donors, who behave in a manner consistent with the existing literature on voluntary contribution games. There are two notable exceptions. First, donors contribute significantly lower amounts when they can be exploited and the exploitation is unobservable. Second, when exploitation is observable managers are successful at maintaining contributions at intermediate levels until end periods when contributions fall to zero. This results in average contribution levels that are not different from treatments where exploitation is not possible. These results suggests one potential impact agency has on the provision of public goods is through the transparency offered by the organizations producing the public good. ^ The final essay asks the basic question of whether behavior commonly observed in linear public goods games differs when the game is played in a two-game ensemble. This is an important question because individuals face multiple giving opportunities or multiple options for giving within a single organization. The results suggest that even when the two games are identical there is a spillover of information between the two games. Certain treatments fail to be effective at raising average contributions when the games are played in a two-game ensemble; this includes non-monetary sanctioning and the display of digital photos. In contrast, lowering the cost of contribution in one game of the ensemble is effective at raising average contributions for that game. Together the results support the position that games should be considered in ensembles instead of in isolation.^

]]> Justin D Krieg Economics, General http://docs.lib.purdue.edu/dissertations/AAI3556332 http://docs.lib.purdue.edu/dissertations/AAI3556332 Wed, 22 May 2013 15:52:10 PDT In this work, a low-order five state model of the air handling system for a multi-cylinder variable geometry turbocharged diesel engine, with cooled exhaust gas recirculation and flexible intake valve actuation, is developed and validated against 286 steady state and 62 transient engine operating points. The model utilizes engine speed, engine fueling, EGR valve position, VGT nozzle position and intake valve closing time as inputs to the model. The model outputs include calculation for the engine flows as well as the exhaust temperature exiting the cylinder. The gas exchange model captures the dynamic effects of not only the standard air handling actuators (EGR valve position and VGT position) but also intake valve closing (IVC) timing, exercised over their useful operating ranges, and thus is critical for designing robust controllers. The model's capabilities are enabled through the use of analytical functions to describe the performance of the turbocharger, eliminating the need to use look-up maps; a physically-based control-oriented exhaust gas enthalpy sub-model, and a physically-based volumetric efficiency sub-model. Traditional empirical or regression-based models for volumetric efficiency, while suitable for conventional valve trains, are therefore challenged by flexible valve trains. The added complexity and additional empirical data needed for wide valve timing ranges limit the usefulness of these methods. A simple physically-based volumetric efficiency model was developed to address these challenges. The model captures the major physical processes occurring over the intake stroke, and is applicable to both conventional and flexible intake valve trains. The model inputs include temperature and pressure in both the intake and exhaust manifolds, intake and exhaust valve event timings, engine cylinder bore, stroke, connecting rod lengths, engine speed and effective compression ratio. The model is physically-based, requires no regression tuning parameters, is generalizable to other engine platforms, and has been experimentally validated using an advanced multi-cylinder diesel engine equipped with a fully flexible variable intake valve actuation system. ^ The in-cylinder oxygen fraction serves as a critical control input to these strategies, but is extremely difficult to measure on production engines. Fortunately, estimates or measurements of the oxygen fraction in the intake and exhaust manifold, the in-cylinder charge mass, and residual mass can be utilized to calculate the in-cylinder oxygen fraction. This work outlines such a physically-based, generalizable strategy to estimate the in-cylinder oxygen fraction from only production viable measurements or estimates of exhaust oxygen fraction, fresh air flow, charge flow, fuel flow, turbine flow and EGR flow. The oxygen fraction estimates are compared to laboratory grade measurements available for the intake and exhaust manifolds. The oxygen fraction estimates will be shown to be particularly sensitive to errors in the EGR and turbine flow. To improve the EGR flow estimate, a high-gain observer is implemented to improve the estimate of EGR flow. Furthermore, the in-cylinder oxygen estimation algorithm is developed, and proven, to be robust to turbine flow errors. The model-based observer estimates the oxygen fractions to within 0.5% O ₂ and is shown to have exponential convergence with a time constant less than 0.05 seconds, even with turbine flow errors of up to 25%. The observer is applicable to engines utilizing high pressure cooled exhaust gas recirculation, variable geometry turbocharging and flexible intake valve actuation. ^ Advanced combustion modes, such as diesel PCCI, operate near the system stability limits. In PCCI, the combustion event begins without a direct combustion trigger in contrast to traditional spark-ignited gasoline engine and direct-injected diesel engines. The lack of a direct combustion trigger necessitates the usage of model-based controls to provide robust control of the combustion phasing. The nonlinear relationships between the control inputs and the combustion system response often limit the effectiveness of traditional, non-model-based controllers. Accurate knowledge of the system states and inputs is required for implementation of an effective nonlinear controller. The previously described in-cylinder oxygen fraction estimator, physically-based volumetric efficiency model, PCCI combustion timing model and gas exchange model provide the required information. A nonlinear controller is developed and implemented based upon these models to control the engine combustion timing during diesel PCCI operation by targeting desired values of the in-cylinder oxygen concentration, pressure, and temperature during early fuel injection. (Abstract shortened by UMI.) ^

]]> Lyle E Kocher Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI3556330 http://docs.lib.purdue.edu/dissertations/AAI3556330 Wed, 22 May 2013 15:52:09 PDT Genetic analyses have become indispensable in species conservation. They are increasingly widespread, accessible and inexpensive. In this dissertation I capitalize on these developments to investigate the population genetics of the eastern box turtle, Terrapene c. carolina. Its demographic decline has been well documented but few studies have evaluated the genetic ramifications of this, and none across the subspecies range. I address here three issues central to the conservation of the eastern box turtle. In my first chapter I evaluate the relatedness of individuals at small geographic scales. I found that at four sites across the range, most individuals were unrelated, with only 10% of pairs being first- or second-degree relatives. Computationally reconstructed parental genotypes for 67 subadults suggested that promiscuity is high in box turtles. Though it is thought that dispersal is low in this species, full siblings were found an average of 11.6 km apart. Finally, I failed to detect any population structure at the fine geographic scale. In my second chapter I scaled my population analyses up to most of the species range. I found evidence for only two populations across the range, though this may be a historical signal. The boundary between them followed the Appalachian Mountains, though population delineation may be more likely caused by isolation by distance. In my third chapter I explore the hypothesis that in the highly fragmented Midwest, contemporary gene flow could be operating along riparian corridor habitat, which is often the only remaining hardwood forest in these areas. I found that isolation by distance was significantly higher along direct lines among sample sites than along least cost paths that generally followed riparian corridors. Collectively, these data provide several novel and counterintuitive insights into box turtle biology, which have implications for the conservation of other forest-dwelling taxa and should provide a foundation for further research.^

]]> Steven James Andrew Kimble Biology, General|Biology, Molecular|Biology, Genetics http://docs.lib.purdue.edu/dissertations/AAI3556331 http://docs.lib.purdue.edu/dissertations/AAI3556331 Wed, 22 May 2013 15:52:09 PDT The three-dimensional, nonlinear, coupled orbit and attitude motion of a spacecraft in both planar and spatial reference orbits is explored in this investigation, within the context of the Circular Restricted Three-Body Problem (CR3BP). The motion of a multibody spacecraft, comprised of two rigid bodies connected by a single degree of freedom joint, under the gravitational influence of the Earth and the Moon is examined. Kane's dynamical formulation is employed and a model framework to develop the fully coupled orbit and attitude differential equations that govern spacecraft motion in the CR3BP is realized. The nonlinear variational form of the equations of motion is employed to mitigate numerical effects arising from large discrepancies in the length scales. Within this framework, a process is summarized with steps for implementation resulting in a series of coupled nonlinear equations of motion for the complex spacecraft model. ^ Several nonlinear, periodic reference orbits in the vicinity of the collinear libration points are selected for further investigation and the effects of the orbit on the orientation, as well as the orientation on the orbit, are examined. Attitude maps are employed to summarize the results; the inertia properties of the spacecraft are varied across a periodic family of reference orbits in the vicinity of the collinear libration points. These maps indicate regions, in terms of the orbit size and inertia properties, where the spacecraft maintains the initial orientation with respect to the circular restricted three-body rotating frame. Reference orbits for the system include both planar Lyapunov orbits and three-dimensional halo trajectories. Additionally, the model is extended to include solar radiation pressure and the motion of a solar sail type spacecraft is examined.^

]]> Amanda J Knutson Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI3556329 http://docs.lib.purdue.edu/dissertations/AAI3556329 Wed, 22 May 2013 15:52:08 PDT Instructors teaching professional courses must be willing to continually assess the effectiveness of their courses and make changes when appropriate. Evaluation data from the medical neuroscience course at the Indiana University School of Medicine-Lafayette indicated students' dissatisfaction with the laboratory portion of the course. In response, the instructors initiated this project to create the effective learning environment required to advance student knowledge and attitude. ^ Using the cyclic action research methodology, a set of active learning modules were developed and implemented over a period of three years. The modules employed hands-on activities, incorporated collaborative teamwork, and provided timely feedback. Various types of collected data confirmed that students were highly satisfied with the new lab regarding it as efficient, effective, and engaging. ^ The overwhelming success of the neuroscience laboratory project prompted the application of a similar active learning module in the lab of an anatomy course offered to upper level undergraduates at Purdue University. The new approach resulted in significantly higher exam scores. Furthermore, student surveys indicated remarkable preference for the new approach. ^ By combining sound educational principles with faculty that were committed to improvement, these research projects provided the systemic, rigorous, and data driven framework necessary to create successful learning experiences for students. Such a system can be used to improve courses at any educational level.^

]]> Samar Khirallah Education, Health|Education, Technology of http://docs.lib.purdue.edu/dissertations/AAI3556327 http://docs.lib.purdue.edu/dissertations/AAI3556327 Wed, 22 May 2013 15:52:07 PDT Event-based design inherently decouples software components and enables distributed systems to scale to a large number of components. Event-based distributed systems have to be engineered to disseminate, detect and respond to simple and complex events in a scalable and efficient manner. Engineering complex event-based distributed applications often goes through combining different middleware systems, which are treated as black boxes by the programming language in which the application logic is implemented, decreasing performance. This decrease in performance is more pronounced in the case of applications that change their subscriptions at a high frequency, e.g., algorithmic trading. ^ This dissertation uses the EventJava framework, consisting of the EventJava programming language and two middleware systems—the Beretta content-based publish/subscribe system and the GenTrie event correlation system—to demonstrate that the efficiency of event-based distributed applications can be increased by aligning middleware systems with specialized programming abstractions. EventJava is an extension of Java with advanced support for event-based distributed programming, including event correlation, unicast and multicast of events. The EventJava compiler uses definitions of complex events to generate an optimized complex event detection component, called GenTrie, at each event consumer. GenTrie consists of an event flow graph, that is designed to discard unwanted events early and to effectively store events that partially match correlation patterns. The EventJava compiler leverages strong event typing and represents all subscriptions in a normalized form as a combination of value intervals and set inclusions without compromising on expressiveness. This, in turn, is leveraged by Beretta, to (1) split subscriptions into predicates based on individual event types and attributes and to efficiently regroup these in interval trees and hash maps yielding excellent subsumption properties, and (2) improve the efficiency of matching events to subscriptions for routing events from publishers to subscribers. Normalization also enables the EventJava compiler to systematically introduce variables into predicates to efficiently perform subscription updates, which are vital to emerging event-based distributed applications in high frequency algorithmic trading, mobile social networking, traffic management, etc. ^ In our empirical evaluation using real world and statistical benchmarks, we demonstrate that the use of the EventJava framework can significantly increase the performance of event-based distributed applications. We have used a real world algorithmic trading benchmark for performance evaluation, by identifying all system and workload parameters and varying them to demonstrate the scalability of our techniques.^

]]> Jayaram Kallapalayam Radhakrishnan Computer Science http://docs.lib.purdue.edu/dissertations/AAI3556328 http://docs.lib.purdue.edu/dissertations/AAI3556328 Wed, 22 May 2013 15:52:07 PDT Development of two highly diastereoselective synthetic methodologies and the total synthesis of fungal natural product Viridiofungin A have been described. A reductive aldol process that features L-Selectride reduction of chiral or achiral enone followed by reaction of the resulting enolate with optically active alpha-alkoxy aldehydes proceeded with excellent diastereoselectivity has been described. The resulting α,α-dimethyl-β-hydroxy ketones are inherent to a variety of biologically active natural products. The development of a practical synthesis of unique nucleoside derivatives via a TiCl₄ promoted multicomponent reaction of optically active dihydrofuran, ethyl pyruvate/glyoxylate, and a TMS protected nucleobase in a single-pot operation has been described as well. A stereoselective synthesis of (-)-viridiofungin A has been accomplished. The convergent synthesis utilized a unique highly diastereoselective multicomponent reaction between optically active phenyldihydrofuran and an α-ketoester to provide two chiral centers including a quaternary carbon center in a single step. Other key steps include an acyloxycarbonium ion mediated tetrahydrofuran ring opening reaction and a Julia-Kocienski olefination.^

]]> Jorden P Kass Chemistry, General|Chemistry, Organic http://docs.lib.purdue.edu/dissertations/AAI3556326 http://docs.lib.purdue.edu/dissertations/AAI3556326 Wed, 22 May 2013 15:52:06 PDT This dissertation examines changing and varying patterns of health disparities in different institutional settings under Chinese market transition. Time, regions, and economic sectors serve as a concrete institutional context according to heterogeneity of Chinese economic reform. This dissertation accordingly consists of three studies that use temporal approach, regional approach, and segmentation approach to operationalized market transition and explore the link among institutional transformation in general and Chinese market transition in particular, social stratification, and health disparities using data from Chinese Health and Nutrition Survey (CHNS). A longitudinal analysis (Chapter 2) and cross-regional comparison (Chapter 3) compares effects of human capital (education) and political power (cadre status) on self-rated health across time and regions in reform-era China. Mixed ordinal logistic analyses show that education has a stronger relationship with health in more recent years (i.e., 2006) and in more marketized region (i.e., coastal region). The association of cadre status with health is shown to be weaker in more recent years and in more marketized region, however its negative association fails to reach statistical significance. Finally, a cross-sectoral comparison study (Chapter 4) focuses on two socioeconomic indicators, income and education, showing a more prominent relationship between SES and self-rated health in the private sector of urban China.^

]]> Soyoung Kwon Geography|Health Sciences, Epidemiology|Sociology, Demography http://docs.lib.purdue.edu/dissertations/AAI3556325 http://docs.lib.purdue.edu/dissertations/AAI3556325 Wed, 22 May 2013 15:52:05 PDT Given the consistently poor postschool outcomes of individuals with high incidence disabilities, there is a need to examine the transition services provided to them while in school. This secondary data analysis explored the transition services received by individuals with high incidence disabilities through the National Longitudinal Transition Study-2 (NLTS2). Data analysis was disaggregated by the five disability categories included in this study – LD, MID, EBD, ADHD, and SLI per availability of sufficient cases. Aggregated analyses combining all the five disability categories were conducted when disaggregated analyses were not possible. Along with receipt of transition services, the researcher examined whether the receipt of these services differed by school and individual demographic variables as well as the relationship between transition services and postschool outcomes. The relationship between postschool outcomes and transition goals was examined along with the extent to which individuals achieved their transition goals as well as the transition services received by individuals who achieved their transition goals were evaluated. Last, transition services received by individuals with high incidence disabilities after school exit were examined. Main findings indicated life skills and employment-related transition activities, including school sponsored work and paid employment experiences, received by individuals with LD and high incidence disabilities were not related to their independent living and employment outcomes respectively. In contrast, inclusion in general education for core content areas was significantly related to participation in postsecondary education any time after school exit. Additionally, transition services received in school varied based on individual's disability identification. Aside from the relationship between services and outcomes, transition planning occurred for the majority of individuals with high incidence disabilities. In terms of postschool outcomes, the majority of the individuals with high incidence disabilities experienced paid employment after leaving school and reported earning more than minimum wage at their current or most recent job. Across time, individuals most frequently achieved their transition goals related to competitive employment, followed by postsecondary education, and independent living. Overall, individuals who met their employment, postsecondary education, and independent living goal either immediately or in the long term received the corresponding transition services. Finally, very few individuals received transition services related to job training or life skills training after school exit.^

]]> Gauri Salil Joshi Education, Special http://docs.lib.purdue.edu/dissertations/AAI3556324 http://docs.lib.purdue.edu/dissertations/AAI3556324 Wed, 22 May 2013 15:52:05 PDT Quinone reductase 2 (QR2) is a cytosolic enzyme capable for activating compounds and rendering them capable of causing DNA damage (i.e. DNA alkylation). QR2 has recently been implicated in neurodegenerative diseases such as Parkinson's Disease and schizophrenia, where patients show significant elevation in cellular levels of QR2. Also, the increased levels of reactive oxygen species (ROS) in these patients has been correlated with increased QR2 levels, as its electron transfer mechanisms activate quinones to generate ROS. Here, we report the identification of novel QR2 inhibitors that can potentially be used as new therapeutics for the treatment or prevention of neurodegenerative diseases or to decrease overall toxicity levels of xenobiotic compounds due to QR2. Furthermore, we utilized non-toxic natural products as starting scaffolds to identify inhibitors of QR2. ^ First, the chemical extraction on blueberries, grapes and red wine was performed to isolate small molecules capable of binding to and inhibiting QR2 activity. Through the use of X-ray crystallographic assisted dereplication (CrystAssist), quercetin and quercetin-sugar derivatives were identified that bind to QR2. The binding of these molecules was verified using HPLC and UF-LC/MS (Ultra filtration), in conjunction with enzyme kinetic studies. The extracts were also tested for their ability to inhibit QR2, and the IC₅₀ of the blueberry extract was approximately 10 µg/mL. Finally, a series of synthetic analogs was evaluated for their ability to inhibit QR2 activity, and a structure-activity relationship was developed that incorporated kinetic data, e.g. IC₅₀ values and X-ray crystallographic data on QR2-inhibitor complexes.^ To further identify QR2 compounds with the potential to decrease oxidative stress (because of QR2 inhibition), we evaluated a series of synthetic resveratrol analogs. Similar to the quercetin analogs, we correlated their potency (IC ₅₀ values) with their structures in complex with QR2, utilizing X-ray crystallography. In this series, over 80 resveratrol analogs were evaluated for inhibition towards QR2, of which measurable potency was observed in 30 compounds. The range in affinity of the 30 compounds was over 2000-fold (from 84 nM to 175 µM), the largest range in affinity as well as the largest number of compounds evaluated of one series as QR2 inhibitors. ^ The third natural product scaffold explored was a metabolite, ammosamide, generated from the isolate of deep-sea marine extracts that showed potent QR2 inhibitory activity. A series of synthetic analogs of ammoasamide was found to display exceptionally high affinity towards QR2, with several compounds demonstrating IC₅₀ values in the low nanomolar range. Using X-ray crystallography, the binding orientations of these analogs in complex with QR2 was determined and were found to be unique. Subtle substitutions in the ammosamide ring structures resulted in drastically different orientations within the QR2 active site. In general, the highest affinity compounds preferred a particular orientation, however, the third most potent compound in the series (PVN-4-28) flips over the y-axis and rotates + 90° relative to the two most potent inhibitors (PVN-5-59 and PVN-4-28). These correlations indicate that binding orientation is not entirely driving by potency of the compound. ^ Finally, it was demonstrated that the novel QR2 inhibitors (from the ammosamide series) are capable of reversing cellular toxicity induced upon increasing menadione concentrations. Menadione is a quinone-containing compound that is metabolized by QR2. It has been hypothesized that menadione reduction results in radical formation, that with the reaction with molecular oxygen, superoxide is formed and is cytotoxic. Here, the addition of the ammosamide analogs was found to counteract the toxicity of increasing menadione concentrations. (Abstract shortened by UMI.)^

]]> Katherine C Jermihov Biology, General|Biology, Molecular|Biology, Cell|Chemistry, Biochemistry http://docs.lib.purdue.edu/dissertations/AAI3556322 http://docs.lib.purdue.edu/dissertations/AAI3556322 Wed, 22 May 2013 15:52:04 PDT Multi-hop wireless mesh networks have emerged as an accepted communication paradigm over the last decade, although their performance is yet to reach to its full potential. Different applications of these networks, such as large-scale metropolitan wireless communication, institutional coverage, battlefield connectivity, etc., often demand highly optimized network performance. To address this issue, this dissertation addresses the problem of performance optimization in multi-hop wireless mesh networks. ^ We maneuver our study on the performance optimization through focusing on different layers in the protocol stack. First, we start at the network layer. We design an energy-efficient network architecture to support high-data-rate applications over low-power wireless meshes, i.e., wireless sensor networks. Here, we study the notion of deploying a high-power radio, 802.11, to augment the network having only conventionally used low-power 802.15.4 radio such that we can guarantee improving the overall energy-efficiency of the network. To achieve the goal, we separately investigate network-level energy efficiencies of both the radios, and then propose the energy-efficient architecture exploiting the findings of the investigation. Our proposed architecture utilizes a delicate balance between the power consumptions of both the radios, which we determine using a cross-layer mathematical model. A real testbed implementation reveals that the proposed network architecture significantly improves the overall energy efficiency of a low-power wireless mesh. ^ Next, we study performance optimization at the transport layer. Here, we specifically focus on reliable data transmission at the transport layer. Our first contribution in this case is based on the observation that the performance of reliable data transmission protocols, such as TCP, depends on the dynamic adjustment of a parameter called retransmission timeout, which in turn depends on the dynamic estimation of round trip time. We propose a stateful Q-learning based technique to dynamically estimate the round trip time. The proposed technique incurs low overhead, making it particularly suitable for networks of embedded systems such as wireless sensor meshes. Besides, the technique substantially improves network performance, which we validate through simulation and real testbed experiments. In addition, we also study on congestion control over wireless mesh networks as the congestion control mechanisms exhibit a substantial influence on overall network performance. We propose end-to-end congestion control mechanisms for both ad-hoc and infrastructure wireless mesh networks. The mechanism for ad-hoc wireless mesh networks is based on the use of a neural network. Besides, the other mechanism for infrastructure wireless mesh networks is based on the use of a decision theory called multi-armed bandit problem. One of the key advantages of these proposed mechanisms is that neither of them involves any radical changes to TCP. Moreover, simulation results and real testbed experiments demonstrate that the proposed congestion control mechanisms can significantly improve the network performance. ^ Finally, we investigate the performance optimization from the upper layers, i.e., the layers that reside on top of the transport layer. Here, we specifically focus on performance optimization over multi-radio networks. First, we study the notion of splitting data, originated from a single flow, over multiple radios. In the study, we propose to perform the splitting from the application layer, as the splitting vastly depends on specific requirements of the application and the application, itself, best knows its own requirements. Besides, we do not have to make any change in existing system architectures in the case of the proposed application-layer data splitting. Moreover, the proposed splitting mechanism exploits a prediction model, and thus incurs no overhead in the network. In addition to such splitting, we also study flow-level data splitting. The notion of flow-level splitting exhibits the potential to improve network performance to a great extent in presence of a mix of different types of flows in the network. In the study on flow-level splitting, first, we analyze coherency between characteristics of the different types of flows and attributes of different radios. Then, we propose a mechanism for flow-level data splitting by exploiting the coherency found from our analysis. We evaluate both of our proposed splitting mechanisms through simulation and real testbed experiments, which uncover their potentials to significantly improve network performance. ^

]]> A. B. M. Alim Al Islam Engineering, Computer http://docs.lib.purdue.edu/dissertations/AAI3556323 http://docs.lib.purdue.edu/dissertations/AAI3556323 Wed, 22 May 2013 15:52:04 PDT The legume family (Fabaceae) is the third largest family of higher plants, including a number of agriculturally important crops. Recent progress in genome sequencing of multiple legume species has provided useful resources to study chromosome biology in combination with fluorescence in situ hybridization (FISH) technology. In this thesis research, we report chromosome studies of two important legume crops: common bean (Phaseolus vulgaris ) and cowpea (Vigna unguiculata). Using a large set of genome sequencing data and bacterial artificial chromosome (BAC) end sequences, centromeric satellite repeats were identified and characterized in common bean. We found several interesting features of centromere structures unique to common bean. Using the centromeric repeats, subtelomeric repeat khipu, rDNAs, and chromosome-specific BAC clones, a FISH-based karyotype map of common bean was established. We applied these karyotyping tools to several common bean accessions and relatives. Comparison of these karyotype maps showed the conservation and diversity of the genome at the chromosomal level. We also investigated chromosomal structure of cowpea, a closely related species of common bean. We analyzed pericentromeric and centromeric regions associated with interesting chromosome structures and identified chromosome-specific BAC clones, which will help further genome analyses of cowpea including on-going genome sequencing project. Overall, the data obtained in this thesis advances our knowledge on genome and chromosome structure and evolution in common bean and its relatives and in cultivated cowpea.^

]]> Aiko Iwata Biology, Genetics|Agriculture, Plant Culture http://docs.lib.purdue.edu/dissertations/AAI3556321 http://docs.lib.purdue.edu/dissertations/AAI3556321 Wed, 22 May 2013 15:52:03 PDT The primary purpose of this study was to determine whether Blissymbolics have the potential for being developed into a tactile symbol communication system. Tactile techniques are used by many individuals with augmentative and alternative communication (AAC) needs. Tactile processing is optimized by the use of minimalistic stimuli, i.e., stimuli that do not contain superfluous material. Blissymbolics is a minimalist graphic symbol system that was originally developed for communication through visual means. In the present study, Blissymbols were modified to a form that could be sensed through touch. This modification consisted of raised-line renderings of Blissymbols made on thermal expansion paper. These raised-line representations were tactually minimalistic because of the stylistic simplicity of the Blissymbolic graphic image from which they were derived. Minimalism may be critical for tactile discernment of Blissymbols. A pilot test with raised-line Blissymbols found that it was possible to reliably discern Blissymbols from each other through haptic processing. This indicated that Blissymbolics may have the potential for serving as the foundation for the development of a tactile symbol system. The pilot test, however, was limited in the number of Blissymbols that were tested. Only four simple Blissymbols (sometimes referred to as Blissymbol elements) were tested. A more comprehensive examination of tactile discernment of Blissymbols is needed. ^ An objective of the following research was to develop and implement a protocol for a more comprehensive examination of the tactile discrimination of Blissymbols. The basis of Blissymbolics is a core of simple Blissymbols that can be combined to produce a multitude of compound symbols with meanings that differ from the simple symbols that comprise the compound. For a tactile symbol system based on Blissymbolics to be successful, it is critical for the simple Blissymbols to have the capacity to be tactilely discriminated from each other. The method for testing tactile discrimination was similar to that used in the pilot test. It entailed having participants tactilely exam a target Blissymbol and to correctly identify through tactile means a duplicate of the target from among foils consisting of tactile Blissymbols that differ from the target. ^ To determine whether Blissymbolics have the potential for a tactile symbol communication system, a criterion for was established. The criterion was that at least 80% of the simple Blissymbols tested must have discrimination scores of 90% correct or better. Eighty-four percent of the simple Blissymbols tested had discrimination scores of 90% correct or better. Thus, Blissymbols exceed the established criterion and appear to have the potential for being developed into a tactile symbol system. Moreover, the total number of tactile discrimination trials was 1548. Of this total, the overall percentage of correct tactile discrimination responses was 94%. This is a considerable number of discrimination trials with a very high percentage of correct responses and can be considered as corroborative to the above performance measures. ^ Identification of simple Blissymbols that are easily confused through tactile processing will be critical for developing a tactile symbol communication system. Symbols that are easily confused through haptic processing will not be viable in their present form for a tactile communication system. Another objective of the present study was the identification of potentially problematic simple Blissymbols. A total of 74 simple Blissymbols were tested. Of those 74 symbols, 4 were identified as statistical outliers because of their low tactile discrimination performance. These 4 symbols are not suitable candidates in their present form as tactile Blissymbols. An additional eight Blissymbols had discrimination performance of less than 90% correct. The performance of these eight symbols was not sufficiently low enough for them to be statistical outliers but because they were below the 90% criterion they should be consider as questionable in regards to their capacity to serve as a tactile Blissymbol. The four unsuitable and eight questionable symbols should be examined to determine appropriate remediation for use as tactile symbols. (Abstract shortened by UMI.)^

]]> Mickey Isaacson Education, Special|Education, Technology of http://docs.lib.purdue.edu/dissertations/AAI3556319 http://docs.lib.purdue.edu/dissertations/AAI3556319 Wed, 22 May 2013 15:52:02 PDT Elucidating the mechanisms involved in replication of Alfalfa mosaic virus (AMV) will contribute to both plant pathology and animal virology. Part of this dissertation focuses on determining the location of virus replication in the cell and the mechanism that targets the AMV replication complex. With confocal microscopy of live cells, it was shown that the two AMV replicase proteins, P1 and P2, associate with the tonoplast during infection. When expressed alone, P1-GFP colocalizes with the endosome and multivesicular bodies (MVB). When P1 and P2 are expressed together, P1 recruits P2 to MVB-like structures. With the addition of at least one of the full length AMV RNAs and P2, P1-GFP associates with the tonoplast, suggesting that formation of an active replicase complex is required for transport of the complex to the tonoplast through the prevacuolar compartment (PVC). Because full length RNA is required, it is likely that the 5' and/or 3' UTRs of the AMV RNA play a role in this targeting. ^ Identifying the host proteins that interact with AMV proteins will help define the strategies that AMV employs to evade the cell's defense system to replicate and move to the next cell. Using a yeast two-hybrid assay, AMV coat protein (CP) was shown to interact with PsbP, which is a component of the oxygen evolving complex (OEC) of Photosystem II (PSII). This interaction was confirmed in Nicotiana benthamiana by bimolecular fluorescence complementation (BiFC). BiFC assays of CP mutants indicated that the N-terminus of AMV CP was not required for PsbP and CP interaction; however, the C-terminal 37 amino acids were required, which suggests that this region of CP interacts with PsbP or that CP dimerization, which requires the C-terminal region, is involved in PsbP-CP interaction. To further investigate under what conditions CP and PsbP interact, CP mutants were made with the 191^st, 197^th and 198^th amino acids changed to alanines and the AMV CP and PsbP interaction was disrupted. This indicates that AMV CP dimerization is needed for the interaction with PsbP to occur. To determine whether PsbP positively or negatively affects AMV replication, we investigated the virus susceptibility of N. tabacum plants that have been silenced for PsbP expression by RNAi. It was shown that PsbP is down-regulated during AMV infection, and that the down-regulated plants were more susceptible to AMV infection.^

]]> Heather Marie Hutchens Biology, Molecular|Biology, Botany|Biology, Virology http://docs.lib.purdue.edu/dissertations/AAI3556320 http://docs.lib.purdue.edu/dissertations/AAI3556320 Wed, 22 May 2013 15:52:02 PDT A complex ball quotient can be smoothly compactified to be a projective algebraic manifold. It is interesting to distinguish the differences between the category of Riemannian metrics and Kahler metrics on this compactified space. The present thesis is a result in this direction. We show that there exists a projective algebraic manifold which supports a Riemannian metric with non-positive Riemannian sectional curvature but no Kahler metric with the same curvature condition. ^ We first show that the canonical line bundle is positive on the compatifying divisors. With respect to the metric of the compactified manifold, the Ricci tensor is zero along these divisors. We can then show that it is impossible for a Kahler metric on such a manifold to have non-positive holomorphic bisectional curvature. ^ On the other hand, if the metric on the compactified manifold is of non-positive Riemannian sectional curvature, then the holomorphic bisectional curvature must be non-positive, because it can be written as a sum of the Riemannian sectional curvature. Hence, this metric is not Kahler.^

]]> Tsz Ho Ip Applied Mathematics|Mathematics http://docs.lib.purdue.edu/dissertations/AAI3556318 http://docs.lib.purdue.edu/dissertations/AAI3556318 Wed, 22 May 2013 15:52:01 PDT The present study examined potential employees' (university students) perceptions of employer branding of companies they seek to work for upon graduation. An extensive review of the literature indicated a need for a better understanding of perceptions of hospitality and tourism management students regarding employer branding and the factors that affect those perceptions. A total of 559 (78.4%) students of hospitality and tourism management, in West Lafayette and Calumet campuses, at Purdue University were participated and completed the questionnaire among 713 students. The study investigated potential employees' (university students') perceptions of employer branding and the impact that demographic factors such as gender, academic level, grade point average (GPA), internship experience, work experience, leadership experience, and impressions of recruiters' behaviors play on their perceptions. The results identified the factors that played had a significant influence on students' perceptions of the three components of employer branding. Those factors were gender, GPA, level of leadership in student organizations, amount of work experience, and students' impressions of recruiters' behavior. However, the other variables including academic level and number of students' internship experiences did not reveal any significant influence on students' perceptions of employer branding. This study suggests practical implications for the hospitality and tourism industry in developing more effective marketing strategies to attract talented employees to the industry. The significance of the research lies for hospitality and tourism companies is related to helping them develop a competitive advantage in recruiting talent. A service organization's long-term success in a competitive market is essentially determined by its employees and its employer brand image.^ Key words: human resource management, brand image, employer branding, recruitment, hospitality and tourism management students^

]]> Yoonkyung Katie Hur Business Administration, Management http://docs.lib.purdue.edu/dissertations/AAI3556317 http://docs.lib.purdue.edu/dissertations/AAI3556317 Wed, 22 May 2013 15:52:00 PDT Low-thrust engines are appealing for use on both earth-based satellites and interplanetary spacecraft. The advantage to using low-thrust engines as the primary means of propulsion is in their high specific impulse, which means that a spacecraft can operate longer and/or carry less fuel. These engines are only capable of very low-thrust, which means they have to operate continuously. A challenge in using such engines is in the trajectory design where traditional methods used for high-thrust engines do not apply. This dissertation presents several techniques, both open-loop and closed-loop, for the guidance of low thrust spacecraft. ^ First, computationally simple strategies are proposed for both the open-loop trajectory design and the closed-loop control of both two-dimensional and three-dimensional low-thrust transfers. The open-loop design approach is based on constructing the acceleration vector so that certain characteristics of the trajectory follow desired profiles. These profiles are designed to guide a low-thrust spacecraft from an initial circular orbit to a different circular orbit. In the two-dimensional case, the orbits will be coplanar. For the three-dimensional case, there will be an inclination change. In addition, the way in which the acceleration vector is constructed allows for its maximum magnitude to be adjusted to be arbitrarily small by making the total transfer time arbitrarily large. The closed-loop guidance strategy is to formulate the acceleration so that orbital characteristics will follow the profiles constructed through the open-loop design process even with disturbances acting on the spacecraft. Both the open-loop and closed-loop strategies will be applicable to both interplanetary and planet-centered transfers. In addition, the control laws are designed so that the acceleration components have analytical form. ^ Next, novel numerical methods for solving nonlinear optimal control problems based on differential transformation (DT) are proposed for the first time to solve low-thrust interplanetary trajectory problems. The differential transformation algorithm is being used for solving the two-point boundary value problems (TPBVP) that result from the indirect optimization approach. This algorithm converts the system of differential equations and its boundary conditions to a set of nonlinear algebraic equations, where solutions can be obtained more quickly. Moreover, the algorithm finds solutions in an analytical form. In this dissertation, the DT is shown to be faster than the multiple shooting method for solving TPBVP's. It is then applied to find several optimal interplanetary trajectories using as initial guesses the trajectories from the open-loop computationally simple controllers. ^ Further, one of the computationally simple controllers is used to prove that there is no solution to the optimal control problem where the final time is free. This fact is also demonstrated by trying to solve a TPBVP where both the final state and final time are free, as the DT algorithm does not converge to a solution. However, the DT algorithm does converge to a solution for the TPBVP when the final time is free but the final state is fixed. This contradiction is due to the fact that the TPBVP is derived from necessary but not sufficient conditions. ^ Finally, a nonlinear model predictive control algorithm (NMPC) is proposed that incorporates a differential transformation based algorithm for the repeated solution of the open-loop optimal control problem every time there is a new state measurement. Then this new NMPC algorithm is applied to several interplanetary low-thrust trajectory tracking problems. It is shown to be more robust with respect to measurment delays than the linear quadratic regulator. The NMPC algorithm is also adapted to quickly find a new optimal trajectory after a severe disruption such as from engine failures.^

]]> Rosemary Chia-Hua Huang Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI3556314 http://docs.lib.purdue.edu/dissertations/AAI3556314 Wed, 22 May 2013 15:51:59 PDT Pharmaceutical salts are commonly used in the final solid dosage form. Altering the ionization state of the active pharmaceutical ingredients (APIs) may lead to several advantages including increased solubility and improved solid state properties relative to the neutral form. In addition, salt formation may be utilized to improve the chemical stability of the compound. Ionizable drug substances can form salts by coupling with counterions. However, the salt formation of weak acids/bases can be problematic due to the occurrence of disproportionation, the conversion of salt form back to its free form in the solid state. This conversion, which results in a change in ionization state of the API, can significantly affect solubility, solid state properties and chemical stability and thus can ultimately compromise the effectiveness of the drug. Although salt forms are widely utilized in the pharmaceutical industry, disproportionation in the presence of moisture and excipients is not well understood. This research aims to provide a fundamental understanding of disproportionation in the presence of moisture and thus assist formulators in making rational formulation and storage condition choices based on the API properties, instead of using a trial and error approach. This will avoid problems encountered later on during development and improve the safety and reproducibility of the final dosage form. This work shows that the properties of the salt, specifically pH_max and buffering capacity, play important roles in influencing the disproportionation tendency and that the storage conditions (temperature and relative humidity) as well as some aspects of formulation design (drug to excipient ratio and particle size) also have significant influence on the extent of disproportionation in the solid state. In addition, the link between chemical instability (specifically oxidation) and ionization state was demonstrated in this work. It was found that the free base of sertraline was prone to oxidation whereas its salt counterparts have superior stability against oxidation due to their ionized state. ^ The change in ionization state occurs not only occur in solid state formulations as described above, but also takes place in the solution state. Due to the physiological pH variations in the human body, some ionizable compounds may be prone to the conversion from the ionized to an unionized form during delivery. Because the unionized form usually has lower solubility than the ionized form, ionizable compounds can be susceptible to supersaturation and subsequently precipitation when entering a pH environment that favors the formation of unionized species, with precipitation leading to a decrease in solution concentration. The decrease in solution concentration can impact the extent of absorption and in turn affect the bioavailability. It is thus critical to understand the pH-induced precipitation behavior of ionizable compounds and explore the possibility of utilizing formulation strategies to maintain higher solution concentrations following pH changes. For this work, a pH-metric titration method was utilized to study the precipitation behavior of several APIs. It was discovered that a compound's solution behavior is strongly influenced by the solid state properties of the precipitate. Compounds that precipitated as a metastable form exhibit a prolonged supersaturation behavior whereas a short-lived supersaturation was observed for compounds that precipitate as the most stable crystalline form. In addition, the effectiveness of utilizing polymers to modify the pH-induced precipitation behavior of APIs was evaluated by measuring wide angle x-ray scattering (WAXS) of the precipitates using synchrotron radiation. Here, some polymers were found to change the precipitation behavior by inhibiting the formation of a crystalline precipitate. The use of synchrotron radiation to analyze the solid state properties of precipitates was demonstrated to be an effective approach that didn't require large amounts of solid or extensive sample preparation.^

]]> Yi-Ling Hsieh Health Sciences, Pharmacy http://docs.lib.purdue.edu/dissertations/AAI3556313 http://docs.lib.purdue.edu/dissertations/AAI3556313 Wed, 22 May 2013 15:51:59 PDT The search for a sustainable and renewable source of energy is of utmost importance to offset increasing energy demands and the decreasing amount of finite resources. This has led to great interest in the utilization of solar energy, more specifically, converting solar energy to chemical energy, which allows for the storage and transport of energy. A particularly promising area in this field is solar water oxidation, or the conversion of sunlight and water to hydrogen and oxygen, which recombine in a fuel cell to release energy and water. ^ To date, a suitable material for use as a photoelectrode in a photoelectrochemical cell for solar water splitting has not been identified. An ideal photoelectrode should have a band gap ca. 2.0 eV, and be inexpensive, stable, and benign. The electrochemical synthesis of thin film semiconductors is a facile and inexpensive synthesis method that allows for a high degree of tunability. There are many ternary and quaternary materials that have not been evaluated as photoelectrodes for solar water splitting. An understanding of band edge positions and the effect that doping, substitution, and solid solutions has on the position of the band edges is advantageous because it allows for a targeted search for an ideal photoelectrode for solar water splitting. This thesis focuses on two groups of materials for solar energy conversion, W-based and Bi-based photoelectrodes. Chapters 2, 3, and 5 focus on W-based photoanodes. Chapters 4 and 6 focus on Bi-based photoelectrodes. ^ W-based photoanodes studied include WO₃, CuWO₄, Bi₂WO₆, and CuMoxW_1-xO₄. WO ₃ is a compound that has great promise for use as a photoanode in solar water oxidation because it is inexpensive, non-toxic, and has a band gap of 2.7 eV, which allows it to absorb visible light. However, it is prone to degradation, evidenced by photocurrent decay due to incomplete water oxidation causing accumulation of peroxide on the surface. The stability and selectivity of the oxidation of water in various electrolytes was tested, and the products were qualitatively and quantitatively analyzed. Choosing a photo-electrolyte with the ideal anion and cation for solar water splitting enhances the efficiency and stability of solar water oxidation on WO₃. The photoelectrochemical properties of WO₃ could be improved by synthesizing ternary or quaternary W-based photoelectrodes that retain the advantages of WO₃ and eliminate its disadvantages. CuWO₄, Bi₂WO ₆, and CuMo_xW_1-xO₄ are n-type photoelectrodes that retain some of the advantages of WO₃ and were synthesized to address these shortcomings. All three had increased photo-stability and chemical stability. Bi₂WO₆ had a conduction band edge that was positioned more favorably for water splitting. CuWO₄ and CuMo_xW_1-xO₄ had smaller band gaps that allow them to absorb more sunlight and have higher theoretical efficiencies. ^ Bi-based compounds are also very promising for solar water splitting because they typically have smaller band gaps and conduction band edge positions that are better positioned for water reduction. However, many Bi-based compounds have not been thoroughly studied. Therefore, CuBi₂O₄, BiVO₄, and BiCu₂VO₆ were synthesized and their photoelectrochemical properties were examined because they have appropriately positioned band edges for solar water splitting that make them promising materials as photoelectrodes in a photoelectrochemical cell.^

]]> James Curtis Hill Alternative Energy|Chemistry, General|Chemistry, Inorganic|Chemistry, Physical http://docs.lib.purdue.edu/dissertations/AAI3556312 http://docs.lib.purdue.edu/dissertations/AAI3556312 Wed, 22 May 2013 15:51:58 PDT Square planar platinum(II) complexes have been the subject of intense study for several years due to their many unique properties and potential applications. Exploiting the emission of these complexes allows for a wide range of applications as spectroscopic probes and anticancer reagents. Manipulation of both intra-molecular and inter-molecular interactions allows one to tune the photophysical properties of compounds with great precision. Chapter one of this thesis will introduce the critical role of platinum(II) in medicinal chemistry and basic photophysics of platinum(II) complexes. Chapter two describes the synthesis and studies of a series of novel expanded framework polypyridine platinum(II) complexes that employ a little-explored method of intra-molecular modification. The majority of the compounds exhibit improved photophysics over the parent compound [Pt(trpy)Cl]⁺. Chapter three summarizes a body of work conducted by McMillin group members over the past several years and describes the synthesis and characterization of the missing members of the series. These complexes involving 4'-substituted trpy ligands, exhibit very impressive photophysics and utilize a well-recognized approach to intra-molecular modification. Chapter four describes the solid state photophysical properties of compounds synthesized by the Lu group. These compounds provide excellent examples of classic intermolecular interaction in Pt(II) compounds and MMLCT emission.^

]]> Lauren M Hight Chemistry, General|Chemistry, Inorganic|Chemistry, Physical|Physics, Optics http://docs.lib.purdue.edu/dissertations/AAI3556311 http://docs.lib.purdue.edu/dissertations/AAI3556311 Wed, 22 May 2013 15:51:57 PDT Genetic connectivity is a crucial element of self-sustaining wildlife populations. Anthropogenic barriers, such as interstate highways, can disrupt gene flow by preventing dispersal between groups of individuals. Another gene flow disruptor is isolation by distance (IBD): the principle that population differentiation increases as spatial distance increases, because individuals are more likely to mate with individuals that are geographically proximate rather than distant. Investigating landscape genetics of wildlife populations is an important step towards understanding the landscape features and spatial scales that are relevant to maintaining connectivity. ^ In Chapter 1, I explored the effects of interstate highways on genetic connectivity for six species of mammals in Indiana. These species included raccoon (Procyon lotor), Virginia opossum (Didelphis virginiana), fox squirrel (Sciurus niger), eastern gray squirrel (S. carolinensis), eastern chipmunk ( Tamias striatus), and white-footed mouse (Peromyscus leucopus ). These species represent a range of attributes, several of which affect dispersal ability across the interstate highway. Site characteristics, such as culverts and bridges, were included in the analysis. Population clustering was evaluated using Bayesian population assignment software and population genetic metrics. The results of the population genetic analyses indicated that five of the study species experienced a decrease in gene flow in relation to interstate highways. Smaller species exhibited population differentiation at more sites than the larger species; however, interstate highways were not a barrier to genetic connectivity for fox squirrels. My results are concordant with previous road ecology research; the barrier effects of high-traffic roads are variable, depending on the study species and potential crossing points. These findings may be carefully extrapolated to predict how species of concern may be impacted by high-traffic roads. ^ For Chapter 2, I investigated isolation by distance (IBD) for two wide-ranging mesopredators: raccoons and Virginia opossums. Previous research has failed to detect the scale of IBD for these species, due to small sample sizes or research design. I investigated IBD using samples collected from nine sites across north central, west central, south central and southern Indiana. My methods included a Bayesian population assignment test and matrix correlation methods. In the Bayesian model, raccoons were assigned to three populations, whereas Virginia opossums exhibited panmixia. Spatial autocorrelation results showed a significant positive correlation between genetic and geographic distance between raccoons up to 25 km and for Virginia opossums up to 4 km. Interspecific differences in behavior and dispersal are the likely causes for differences in the spatial partitioning of populations. The results from this research provide crucial information regarding the genetic connectivity of these mesopredators, and may guide predictions of disease transmission.^

]]> Cecilia A Hennessy Agriculture, Wildlife Conservation|Agriculture, Wildlife Management|Biology, Genetics http://docs.lib.purdue.edu/dissertations/AAI3556310 http://docs.lib.purdue.edu/dissertations/AAI3556310 Wed, 22 May 2013 15:51:56 PDT Since the 1960's, composite propellants have been widely used in rocketry applications because of their excellent performance and low cost to implement. Due to their pervasive use, there has been a strong desire for a method to predict the performance of a propellant a priori. The ability to predict performance would accelerate development of solid propellants, minimizing the required amount of costly empirical data. ^ Early flame structure models for composite propellants such as the granular diffusion flame (GDF) and the Beckstead, Derr, Price (BDP) models, were introduced in the 1960's and 1970's respectively. These well-known models involved the development of heuristic relations to predict the burning rate of a composite propellant. Increased computing power in recent years has allowed for more advanced modeling of solid propellants. Models exist today that incorporate detailed chemistry in the gas phase with a simplified geometry as well as a 3-D surface structure using simple chemistry. ^ However, these models lack validation due to the dearth of detailed experimental data on composite propellants. This is due, in part, to the challenging nature of the combustion environment. The flame is particulate heavy, transient, and highly spatially variant. ^ Additionally, composite propellant surface morphology is complex, made up of complex mixtures of oxidizers and fuels. ^ This document summarizes an effort to provide detailed experimental data for todays advanced models that is currently lacking in the literature. Experiments are designed and carried out to quantify the flame structure and surface behavior of various composite propellants. High speed PLIF and high resolution surface imaging are employed at various pressures in order to characterize flame structure and surface behavior. ^ In addition, an attempt is made to begin to improve existing composite propellant models. This is performed by first combining a micro-scale detailed chemistry model and a meso-scale model that includes surface topography. This model is compared with the experimental results and areas for improvement are identified. It is hoped that increased knowledge of the flame structure and surface structure of composite propellants will translate into better a priori predictions of performance eventually. ^

]]> Trevor Hedman Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI3556218 http://docs.lib.purdue.edu/dissertations/AAI3556218 Wed, 22 May 2013 15:51:55 PDT Over the past few decades the induction machine has been chosen for many applications due to its structural simplicity and low manufacturing cost. However, modest torque density and control challenges have motivated researchers to find alternative machines. The permanent magnet synchronous machine has been viewed as one of the alternatives because it features higher torque density for a given loss than the induction machine. However, the assembly and permanent magnet material cost, along with safety under fault conditions, have been concerns for this class of machine. ^ An alternative machine type, namely the asymmetrical reluctance machine, is proposed in this work. Since the proposed machine is of the reluctance machine type, it possesses desirable feature, such as near absence of rotor losses, low assembly cost, low no-load rotational losses, modest torque ripple, and rather benign fault conditions. Through theoretical analysis performed herein, it is shown that this machine has a higher torque density for a given loss than typical reluctance machines, although not as high as the permanent magnet machines. Thus, the asymmetrical reluctance machine is a viable and advantageous machine alternative where the use of permanent magnet machines are undesirable.^

]]> Cahya A Harianto Engineering, General|Engineering, Electronics and Electrical|Physics, Electricity and Magnetism http://docs.lib.purdue.edu/dissertations/AAI3556217 http://docs.lib.purdue.edu/dissertations/AAI3556217 Wed, 22 May 2013 15:51:55 PDT CaaX proteins, including the three predominant Ras isoforms, have a C-terminal tetrapepide motif where "C" is a cysteine, "a" is an aliphatic amino acid and "X" is one of several residues. Proteins terminating in a CaaX box require three post-translational modifications; the final step being the α-carboxyl methylesterification of the terminal cysteine. This methylation reaction is completed by a unique class of methyltransferases known as isoprenylcysteine carboxyl methyltransferase (Icmt). Oncogenic K-Ras mutations are responsible for 30% of all cancers and 90% of pancreatic cancers and methyl esterification is required for K-Ras plasma membrane localization where it needs to be in order to function properly. Icmt is the only protein that methylates K-Ras, driving the pursuit of Icmt as a target for anti-cancer therapeutics. ^ Human Icmt and the yeast homolog, Ste14p, (33- and 26-kDa, respectively) are integral membrane proteins localized to the endoplasmic reticulum (ER). The Icmt family of proteins is believed to bind isoprenylated substrates and the co-substrate via an ordered bi-bi reaction mechanism. These proteins use S-adenosyl-L-methionine (SAM) as a methyl source and have a SAM binding site distinctly different from all other known methyltransferases. ^ Our research has focused on the characterization of the hydrophobic binding site of human Icmt and Ste14p. Here, we report the cellular characterization of a novel human Icmt inhibitor, STAB-F3-Diol. Our findings determine that STAB-F3-Diol deters the growth of pancreatic cancer cell lines, as well as inhibiting Ras activation and Erk 1/2 phosphorylation. In addition, this inhibitor reversed both the K-Ras driven cellular transformation of the PaTu 8902 pancreatic cancer cell line and plasma membrane localization of EGFP-K-Ras. ^ We also investigated the oligomeric state of metal affinity purified His₁₀myc₃N-Ste14p. Furthermore, we determine the ability of Ste14p and human Icmt to recognize and photo-crosslink with a variety of N-acetyl-S-farnesyl-L-cysteine (AFC) and a-factor benzophone-labeled substrates. We found that tagged Ste14p functions as a homodimer or higher order oligomer. The oligomerization state of Icmt is essential to the characterization of the protein and development of substrate based inhibitors. From these studies, we concluded that both the yeast and human proteins were able to recognize and photo-crosslink with each of the substrates to varied degrees. We also found that Ste14p was able to methylate both the AFC and a-factor substrates whereas human Icmt was only able to methylate the labeled AFC substrates.^

]]> Kalub J Hahne Chemistry, Biochemistry http://docs.lib.purdue.edu/dissertations/AAI3556216 http://docs.lib.purdue.edu/dissertations/AAI3556216 Wed, 22 May 2013 15:51:54 PDT Concern over the availability of fossil fuels as well as energy usage and harmful emissions output have produced an interest in alternative fuels, advanced combustion strategies, and increased usage of engine technologies such as variable valve timing (VVT), turbocharging, and exhaust gas recirculation. While alternatives such as biodiesel and ethanol are renewable and can reduce dependence on foreign sources of petroleum, challenges in using these fuels must be addressed in order for optimal performance to be achieved on fuel-flexible vehicles. ^ On compression ignition (CI) engines, biodiesel combustion typically results in decreased particulate matter (PM), unburned hydrocarbon (uHC), and carbon moNO_xide (CO) emissions. However, biodiesel usage also results in increased fuel consumption and nitrogen oxide (NO_x) emissions relative to petroleum-based diesel. These challenges can be addressed through the use of a fuel-flexible combustion control strategy. The approach presented in this work consists of two parts: 1) estimation, whereby the engine control module (ECM) detects the biodiesel blend fraction being supplied, and 2) accommodation, whereby the ECM dynamically changes the control setpoints in order to improve engine performance. A closed loop control method, which accounts for the oxygen content and energy density differences between diesel and biodiesel, has been developed which can be added to the existing ECM control structure to create a fuel-flexible structure. Analysis of the control system indicates that the addition of this fuel-flexible control strategy will not detrimentally affect the overall engine control structure. Experimental validation of this control strategy on a 2007 6.7 liter Cummins ISB series engine at several very different operating modes shows that this fuel-flexible control method greatly reduced or completely eliminated increases in NO_x emissions of up to 30% while largely maintaining the torque/power capacity of a modern diesel engine when operating with biodiesel. Since biodiesel can be created from a variety of different feedstock and can be further processed to alter certain fuel properties, its fatty acid structure can differ. The robustness of the proposed control technique to variations in fatty acid composition is also explored. ^ Fuel-flexible spark ignition (SI) engines permit the increased use of ethanol-gasoline blends. Ethanol is a renewable fuel which has the added advantage of improving performance in operating regions which are typically knock limited due to the higher octane rating of the fuel. Furthermore, many modern SI engines are also being equipped with variable valve timing, a technology which can increase engine efficiency by reducing pumping losses through control of the in-cylinder burned gas fraction (BGF). However, the BGF and ethanol blend can have a significant impact on the combustion timing, such that capturing these effects is essential if the combustion phasing is to be properly controlled. Combustion efficiency is typically tied to an optimal CA50 (crankangle when 50% of fuel is burned) for an engine. A control-oriented model of combustion phasing has been developed and extensively validated across the operating range of a 4-cylinder Renault SI engine for 4 blends of gasoline and ethanol. Furthermore, the model was utilized to determine the impact of ethanol blend and BGF on combustion phasing and on the optimal spark timing. Leveraging the model in this manner provides direct evidence that accounting for the impact of these two inputs is critical for proper spark ignition timing control. The model created in this work has the potential to be used to improve air handling control to avoid the need for throttling and to improve spark timing control to ensure that CA50 occurs at its optimal timing despite changes in fuel and BGF. ^ While fuel-flexible operation in conventional combustion modes presents significant challenges, an interest in abiding by stringent emissions and fuel economy regulations has motivated the investigation of advanced combustion strategies such as premixed charge compression ignition (PCCI) used in conjunction with alternative fuels. PCCI can achieve low emissions and high efficiencies in diesel engines; however, fuel property differences cause a more significant impact in such advanced combustion modes and can make control in these regions more challenging. When biodiesel is used at premixed operating conditions with the engine operating with the stock calibration for diesel fuel, the timing of start of combustion and peak heat release can shift by over 2°CA and 4°CA respectively, nitrogen oxide emissions can increase by over 100%, and torque output can drop by over 30% with respect to engine performance with diesel. A control framework for fuel-flexible PCCI has been developed and theoretical and experimental results demonstrate that: 1) combustion timing control and NO_x control can also be achieved through control of in-cylinder oxygen fraction alone, 2) energy-based fueling provides consistent in-cylinder oxygen fractions between diesel and biodiesel while also matching torque outputs for the two fuels when considered at the same premixed operating point (speed, intake manifold temperature, charge flow, effective compression ratio, and combustion timing).^

]]> Carrie M Hall Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI3556215 http://docs.lib.purdue.edu/dissertations/AAI3556215 Wed, 22 May 2013 15:51:53 PDT Guided by electromagnetics-based first principles, we develop a circuit simulator that allows for the simulation of an integrated circuit including both nonlinear devices and the layout of the linear network in linear (optimal) complexity. Furthermore, it permits an almost embarrassingly parallel implementation on a many-core computing platform, and hence enabling linear speedup. Moreover, it bypasses the step of circuit extraction, producing an RLC (resistor-inductor-capacitor) representation of the linear network without any numerical computation. In addition, it possesses electromagnetics first-principles based accuracy. Application to die-package co-simulation as well as very large-scale on-chip circuits has demonstrated the superior performance of the proposed electromagnetics-based circuit simulator. ^ The efficiency of a circuit simulator is determined not only by the computational cost at each time step, but also by the total number of time steps required to finish one simulation. In this work, we create the first explicit time-domain method that is unconditionally stable, which allows the time step in an explicit method to be solely determined by accuracy irrespective of space step, and meanwhile preserving the strength of an explicit time-domain method in avoiding a matrix solution. This method is further accelerated by a fast DC mode extraction algorithm. This algorithm is capable of decomposing the original large-scale problem rigorously into small problems that are fully decoupled, and then synthesizing the DC solution of the original large-scale problem from the nullspace of the small problems. The aforementioned work has significantly reduced the total number of time steps required to finish one simulation by the proposed electromagnetics-based linear-complexity circuit simulator by many orders of magnitude. ^ Last but not the least, guided by electromagnetic physics, we find a minimal order model of the linear network for a prescribed accuracy. This model is applicable to general circuits irrespective of whether the circuits are dominated by RC-, RLC-, or full-wave physics. For circuits dominated by RC physics, the size of the proposed minimal order model is only 2 regardless of the circuit size. As a result, the proposed electromagnetics-based circuit simulation can be performed on the proposed minimal order model, the size of which is orders of magnitude smaller than the size of the original physical layout, and therefore further speeding up the proposed circuit simulator. ^

]]> Qing He Mathematics|Engineering, Computer|Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI3556213 http://docs.lib.purdue.edu/dissertations/AAI3556213 Wed, 22 May 2013 15:51:52 PDT In recent years the call for school reform has become a rapidly progressing movement of parents, students and whole communities seeking change in the way that students are being educated. Charter schools have emerged nationwide seemingly as the answer to mounting criticism of the traditional public school offering, as school stakeholders seek more educational choices for primary and secondary students. The emergence of charter schools in Indiana followed the call of the Evansville community to create a school with specialized curriculum for all. The success of this initial charter school as a nationally recognized high school is often imitated. The chosen Northwest Indiana study site is a charter school with a specialized curriculum focused on meeting the needs of any student applicant. ^ This quantitative study uses questionnaire data from 61% of the chosen Northwest Indiana Charter School families. The study explores the parental perspectives about the school while comparing their satisfaction level with the charter school to that of past educational settings that their children have attended. The study further breaks down the influences that may drive a parent to select the charter school as their educational site of choice. The questionnaire response data was used to create a parent profile to describe in depth the demographic characteristics of parents who select the charter option. ^ The study finds sufficient evidence that the charter school phenomena at this site can be attributed to like characteristics in the responding families rather than to differences based on income or race/ethnicity. There are not significant differences in satisfaction when the data is stratified using income and ethnicity characteristic factors. The study does find significant differences in satisfaction between the charter school and the student's previous school setting.^

]]> Dawn Y Greene Education, Administration http://docs.lib.purdue.edu/dissertations/AAI3556214 http://docs.lib.purdue.edu/dissertations/AAI3556214 Wed, 22 May 2013 15:51:52 PDT Multi-gate FETs are emerging as promising devices for scaled technologies due to their superior gate control of the channel compared to conventional MOSFETs. In order to utilize the full potential of multi-gate FETs, there is a need for design methodologies which exploit unique technology features to achieve superior design solutions. Moreover, design issues specific to multi-gate FETs need to be identified and addressed using innovative techniques at different levels of design abstraction. This research focuses on device/circuit-level design and analysis of multi-gate FET based SRAMs. For our analysis, we have developed a mixed-mode simulation framework, with the capability of treating quantum mechanical effects in deeply scaled devices. The simulation framework is based on non-equilibrium Green's function (NEGF) models and Taurus simulations for devices. Circuit simulations are carried out using HSPICE with look-up table based Verilog-A models. Using this simulation framework, we explore the device-circuit interactions in multi-gate FET based SRAMs. First, we show that using unique technology features of FinFETs (a type of multi-gate FET), design conflicts in 6T SRAM can be mitigated. To that effect, we propose FinFETs with asymmetric gate underlap and asymmetric source/drain doping to mitigate the read-write conflict in SRAMs and achieve larger cell stability along with leakage reduction. We also explore independent gate FinFET based SRAMs and propose design techniques to improve the cell stability. Next, we propose a double-gate heterojunction intra-band tunnel (HIBT) FET based on different source/drain and channel materials. We show that compared to Si double-gate MOSFET, HIBT FET exhibits lower drain-induced barrier lowering/thinning and lower sensitivity of OFF current to process variations. We also discuss the suitability of the proposed device for low voltage SRAMs. Finally, based on some unique features of FinFETs, we report the possibility of negative-bias temperature instability in n-type silicon-on-insulator FinFETs used as access transistors in SRAMs and analyze its impact on the cell stability and performance. ^

]]> Sumeet Kumar Gupta Engineering, Electronics and Electrical|Nanotechnology http://docs.lib.purdue.edu/dissertations/AAI3556212 http://docs.lib.purdue.edu/dissertations/AAI3556212 Wed, 22 May 2013 15:51:51 PDT The ability to detect biomolecules and chemicals accurately, effectively, and promptly in variety of environments including applications in homeland security, clinical diagnoses, environmental monitoring, food safety, etc. has always been an important issue. For each of these applications, it is highly desirable that a small, ultra-sensitive, versatile and robust sensor be created. ^ During the last decade, enormous progress in the synthesis of 1-D nanostructured materials and nanoparticles has allowed the fabrication of nanometer-sized sensors. Such materials and devices, with large surface-to-volume ratios and Debye length comparable to their small size, have already displayed superior sensitivity for the detection of various chemical and biological species. Their extremely small-scale also enables the miniaturization of sensors (e.g., portable, handheld sensors) as well as their multiplexing functionality to achieve simultaneous detection of multiple target molecules in a given sample. ^ In spite of huge existing research regarding the fabrication of nanoscale bio- and chemical sensors, the understanding of their sensing mechanism has been limited, confused, and contradictory. In this thesis, we develop a comprehensive theoretical framework to correlate the geometry and physical properties of nanoscale sensors to their sensing performance of target molecules. This framework provides the solution for the puzzles arising from the discrepancy in recent experimental results and the classical theory regarding sensor performance and give guidance for approaches about the sensor design and optimization.^

]]> Jonghyun Go Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI3556211 http://docs.lib.purdue.edu/dissertations/AAI3556211 Wed, 22 May 2013 15:51:50 PDT A phenomenological study was conducted examining the decision factors of underrepresented minority (URM) students' lack of plans for graduate school in the college of technology. Research conducted based on Systems Theory found that information, people, and organizations influence students (Berger, 2002). Comparisons were drawn about accuracy and access to information via the institution, research programs, outreach programs, various support systems, and personal networks. Fifteen subjects participated in semi-structured interviews. The researcher probed for in depth knowledge about the unique lived experience (Seidman, 1998). The present study fills a gap in technology literature by examining undergraduates' perspectives about graduate school. An analysis of the factors that determine how underrepresented minority (URM) students decide to attend graduate school was important in highlighting processes, policies, and programs that should be implemented in the College of Technology to assist these students to obtain an advanced technical degree. The present research contributes to the growing knowledge of literature in the field concerning attracting and retaining domestic URM students in technology.^

]]> Ella Shirl Gordon-Donaldson Education, Evaluation|Education, Multilingual|Engineering, General|Education, Higher http://docs.lib.purdue.edu/dissertations/AAI3556210 http://docs.lib.purdue.edu/dissertations/AAI3556210 Wed, 22 May 2013 15:51:49 PDT The structural strength and exceptional deformability of red blood cells (RBCs) can be attributed to an underlying cytoskeleton and protein tethers that anchor it to the membrane. Band 3, a membrane spanning anion transporter, serves as one of the major tethers between membrane and cytoskeleton and RBCs with a deficiency or defect in band 3, or the proteins that interact with it, have reduced deformability and lifespan, often resulting in a hemolytic anemia. Glycophorin A (GPA) is another membrane spanning protein suspected to interact with band 3 and possibly with the cytoskeleton under certain stimuli. While it is clear that band 3 and the cytoskeletal proteins are crucial for red blood cell survival and function, their organization and regulation is not well understood. Single particle tracking (SPT) provides a molecular-level view of the mobility of a protein and can reveal information about its interactions with the underlying cytoskeleton. In order to understand the formation and maintenance of these interactions, band 3 diffusion was measured using SPT on intact RBCs from transgenic mice with cytoskeletal defects. The diffusion of band 3 and GPA were also studied on intact, normal human RBCs and on RBCs with increased band 3 phosphorylation. Hyperphosphorylation of band 3 increased its diffusion ∼2 orders of magnitude revealing a novel mechanism of regulation of the band 3-cytoskeleton interaction. On the other hand, band 3 phosphorylation had no effect on the mobility of GPA suggesting they do not form a tight association though GPA may have other binding partners in the membrane.^

]]> Katie Marie Giger Chemistry, Biochemistry|Biophysics, General http://docs.lib.purdue.edu/dissertations/AAI3556208 http://docs.lib.purdue.edu/dissertations/AAI3556208 Wed, 22 May 2013 15:51:48 PDT Industrialized societies are increasingly characterized by a `care deficit' as a result of the discrepancy between caring needs and the number of available care workers. The need for more care workers stems partly from more opportunities for working women and the need for two-income households to safeguard against financial insecurity. In this study, I consider how care and immigration policies in host countries influence one another and explore the implications. I argue that states with less generous care policies (including childcare provisions and leave-time) and states with more working women are more encouraging of migrant and temporary workers. I build a classification scheme that identifies four scenarios of generosity and openness to identify mechanisms that influence the presence of migrant care workers and targeted policies, followed by a mixed methods approach. First, empirical support is presented to verify the exceptional nature of domestic care work versus preferences for skilled workers. Second, case studies, using process tracing and structured, focused comparison, illuminate how the framing and construction of childcare policy and working women affect specific migration policies for domestic workers. I draw on the empirical results and country specific case studies to help establish broad domestic and international conditions that promote gender equity.^

]]> Holly Gastineau-Grimes Political Science, General|Sociology, Public and Social Welfare|Sociology, Ethnic and Racial Studies http://docs.lib.purdue.edu/dissertations/AAI3556209 http://docs.lib.purdue.edu/dissertations/AAI3556209 Wed, 22 May 2013 15:51:48 PDT Using the entire CLEO-c psi(3770) to DDbar event sample, corresponding to an integrated luminosity of 818 pb^-1 and approximately 5.4 x 10^6 DDbarevents, we measure the form factors for the decays D0 to rho- e+ nu_e and D+ to rho0 e+ nu_e for the first time and the branching fractions with improved precision. A four-dimensional unbinned maximum likelihood fit determines the form factor ratios to be: V(0)/A_1(0) = 1.48 +- 0.15 +- 0.05 and A_2(0)/A_1(0)= 0.83 +- 0.11 +- 0.04. Assuming CKM unitarity, the known D meson lifetimes and our measured branching fractions we obtain the form factor normalizations A_1(0), A_2(0), and V(0). We also present a measurement of the branching fraction for D^+ to omega e^+ nu_e with improved precision.^

]]> Junyan Ge Physics, Elementary Particles and High Energy http://docs.lib.purdue.edu/dissertations/AAI3556207 http://docs.lib.purdue.edu/dissertations/AAI3556207 Wed, 22 May 2013 15:51:47 PDT Mass spectrometry (MS) is considered as a gold standard for chemical analysis. A vision towards clinical/biological mass spectrometry is ongoing, to facilitate development of highly potent devices for biomedical, point of care and/or general purpose in situ analysis. The key developments in this context have been - ambient ionization sources and miniature MS systems. Atmospheric/ambient ionization methods make possible for the interrogation of biological samples particularly in situ. Miniature MS systems allow for simple, efficient, on site analysis. However, their routine combination for the development of high efficiency biological mass spectrometry systems is possible by overcoming certain key technological challenges, particularly the inefficient ion transfer pathway from ion sources (at atmospheric pressure) to mass analyzers (at high vacuum). In this thesis, fundamental electro-hydrodynamic transport studies in MS systems have been made to direct informed development of high efficiency MS systems. ^ Methods and devices have been developed, to collect gas phase ions from ambient/atmospheric pressure ion sources and transfer them over long distances for mass spectrometric analysis. Theoretical studies of ambient ion transport, continuum scale fluid dynamic simulations and experimental tests demonstrate that laminar flow can transfer ions over long distances (over 6 m). The typical angular discrimination effects encountered when sampling ions from ambient ionization sources are minimized, and the sampling of relatively large surface areas is demonstrated. Applications to multiplexed chemical analysis have been demonstrated on samples at locations remote from the mass spectrometer. Ion sampling into relatively small MS inlets and transfer of ions through MS interfaces is studied via multiphysics electro-hydrodynamic simulations. The gas phase ions sampled into MS interfaces need to be delivered to a high vacuum (at ∼10-3 Torr or lower) for mass analysis. In miniature MS systems which use compromised pumping systems to minimize weight and power, this is made possible using a novel interface design v.i.z. discontinuous atmospheric pressure interface (DAPI). The electro-hydrodynamic transport in DAPI is fundamentally different from that in conventional systems and significantly impacts instrument performance. Direct Simulation Monte Carlo methods for gas dynamics and coupled multiphysics models for ion transport have been used to elucidate the dynamics and energetics of DAPI and design high efficiency MS systems for in situ analysis. Based on fundamental understanding gleaned from simulation of DAPI-MS process, simple instrumentation for performing complex ion-molecular chemistry has been designed and evaluated. MS instrumentation development for planetary missions has been explored. The overall study has an impact on instrumentation development of general purpose MS systems.^

]]> Sandilya Venkata B Garimella Chemistry, Analytical|Engineering, General|Engineering, Biomedical http://docs.lib.purdue.edu/dissertations/AAI3556205 http://docs.lib.purdue.edu/dissertations/AAI3556205 Wed, 22 May 2013 15:51:45 PDT RF system complexity is steadily increasing due to demands for multiband and multifunction operation within a single device while maintaining or reducing size, cost, and power consumption. To combat this, efforts are ongoing to develop reconfigurable RF subsystems. RF MEMS switches comprise a crucial building block for such systems. However, cost and reliability concerns have hindered their widespread adoption. ^ In this work, an ohmic contact RF MEMS switch is developed utilizing single-crystal-silicon (SCS) as the structural material while maintaining state-of-the-art performance. Unlike thin-film metals commonly employed in RF MEMS switches, SCS is essentially defect-free and has well-known and repeatable material properties. This makes the switch design insensitive to process variations and amenable to high- yield manufacturing. Measured devices exhibit on state insertion loss of less than 0.3 dB and off state isolation of higher than 30 dB up to 40 GHz and switching time under 4 microseconds. ^ This switch is then used as a repeatable platform for developing an ultra-low-power (60-250 microwatt) IC based in-situ real-time monitoring technique for RF MEMS switch dynamics. The ability to record extremely small displacement bounces (<20 nm) alongside the entire settling event with 99% accuracy in determining contact timing relative to LDV measurements is demonstrated experimentally. ^ Changes in dynamic behavior of RF MEMS switches over lifetime operation are then utilized as a readily and simply observable method of failure prediction for a commercially available device. Rapid increases in the number of bounces are observed which indicate approximately 50-75% of total operation has elapsed. ^

]]> Adam J Fruehling Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI3556206 http://docs.lib.purdue.edu/dissertations/AAI3556206 Wed, 22 May 2013 15:51:45 PDT Real time hybrid simulation (RTHS) has increasingly been recognized as a powerful methodology to evaluate structural components and systems under realistic operating conditions. The idea is to explore and combine the advantages of numerical analysis with physical lab testing. Furthermore, the enforced real-time condition allows testing on rate dependent components. Although the concept is very attractive, challenges do exist that require an improved understanding of the methodology. One of the most important challenges in RTHS is to achieve synchronized boundary conditions between the computational and physical substructures. Test stability and accuracy are largely governed by the level of synchronization. The sensitivity of the RTHS system error to the de-synchronization error is analyzed, from which a worst-case substructure scheme is identified and verified experimentally. This de-synchronization error, which is largely associated with the actuator dynamics, is further analyzed, by studying the sensitivity of the actuator dynamics with respect to the actuator parameter variation. ^ The objective of this study is to develop and validate a robust RTHS framework. The framework hardware development include a reaction system, a servo-hydraulic actuation and control system, a digital signal processing system, and a steel moment resisting frame specimen. An H-infinity loop shaping design strategy is proposed to control the motion of actuator(s). Controller performance is evaluated using the worst-case substructure proportioning scheme. Both system analysis and experimental results show that the proposed H-infinity strategy can significantly improve the stability limit and test accuracy. Another key feature of the proposed strategy is its robust performance in terms of both parametric and non-parametric plant uncertainties, which inevitably exist in any physical system. Extensive validation experiments are performed successfully, including the challenges of multiple actuators dynamically coupled through a continuum frame specimen. These features assure the effectiveness of the proposed framework for more complex RTHS implementations. ^

]]> Xiuyu Gao Engineering, General|Engineering, Industrial http://docs.lib.purdue.edu/dissertations/AAI3556204 http://docs.lib.purdue.edu/dissertations/AAI3556204 Wed, 22 May 2013 15:51:44 PDT This dissertation focuses on the development, evaluation, and validation of a new semi-active control strategy for use with large-scale magnetorheological dampers in structural control applications through real-time hybrid testing. As MR control devices increase in scale for use in real-world civil engineering applications, their dynamics become increasingly complicated. Control designs that are able to take these characteristics into account will be more effective in achieving good performance. A new control algorithm, ODCOC, which utilizes over- and back-driving current control to increase the efficacy of the control device, is proposed. ^ To validate the performance of the new controller under general earthquake excitation and uncertain conditions, a series of three large-scale validation experiments (using large-scale 200kN MR Dampers and steel frames) are performed, including: (1) a three-story linear structure real-time hybrid simulation (RTHS), with a large-scale steel frame and MR damper as tbe physical substructure; (2) a nine-story linear structure realtime hybrid simulation, with a large-scale steel frame and MR damper(s) as the physical substructure; and (3) a non-linear nine-story structure numerical simulation analysis. The performance of the proposed controller is compared to several establish MR damper control methods in each experiment. ^ The main contributions of this research are twofold: (1) RTHS is validated a viable testing technique for large-scale applications, as comparisons to numerical simulations and repeatability testing demonstrate the reliability of this method, and (2) the controller experiments demonstrate the improved structural performance that results when using the ODCOC algorithm compared to other established methods. The ODCOC is able to exceed or match the performance of the other methods in every evaluation category while utilizing less force to accomplish it. ^ From this work, the merits of real-time hybrid testing are demonstrated using large-scale, significant structural components as the physical substructure. RTHS is validated as an acceptable alternative test method. Based on the results of the control performance validation study, using the ODCOC approach in conjunction large- or fullscale MR devices increases the ability of the device to respond in a timely manner to excitation and yields improved global structural responses under seismic loading. Any projects, including both academic and professional engineering applications, that utilize devices at these scales will benefit from employing this control method.^

]]> Anthony Joseph Friedman Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI3556203 http://docs.lib.purdue.edu/dissertations/AAI3556203 Wed, 22 May 2013 15:51:43 PDT With the goal of realizing novel "organometallic molecular wires" for molecular electronic devices, electron delocalization in transition-metal complexes containing linear σ-polyynyl ligands have received a great deal of attention over the last decade. Largely unexplored are metal compounds containing cross-conjugated polyynes, the simplest of which being iso-triacetylene (geminal-diethynylethene or gem-DEE). Recently, on the basis of theoretical modeling, it has been postulated that oligomers of gem-DEE have conductance attenuated by quantum interference effects. We hypothesized that the combination of gem-DEE ligands with both redox (Ru₂) and photoactive (Cr) transition metals will help to unravel the cross-conjugation and quantum interference effects. ^ However, the metallation chemistry of gem-DEE ligands is limited to Pt(II) compounds which limits the investigation of the pi-conjugation therein, due to the electronic saturation of a d⁸ configuration in a square planar environment. Presented herein are the syntheses and characterizations of the first transition-metal complexes containing cross-conjugated ligands beyond Pt(II). An investigation of the pi-conjugation within was performed on two classes of metal σ-gem-DEE complexes in hope of elucidating the cross-conjugation and quantum interference effects: bis-[M]-σ-gem-DEE (where [M] is Ru₂(III,III) and Cr(III) which may be the starting point for oligomers; and dimeric [M]-μ- gem-DEE-[M] (where [M] is Ru₂), which allows for the assessment of the electronic coupling of the two metal termini via the gem-DEE bridge.^

]]> William P Forrest Chemistry, General|Chemistry, Inorganic http://docs.lib.purdue.edu/dissertations/AAI3556202 http://docs.lib.purdue.edu/dissertations/AAI3556202 Wed, 22 May 2013 15:51:42 PDT Gluten, wheat storage protein, exhibits unique ability of forming a viscoelastic dough upon hydration and mixing. It is composed of alcohol soluble proteins, gliadins, and polymeric glutenins. The interactions between gluten proteins, gliadins and glutenins, are responsible for the formation of viscoelastic protein network. Gliadins are recognized as the protein fractions responsible for viscous nature of gluten and, glutenins for the elasticity. High molecular weight subunits of glutenin (HMW-GS) have been found particularly important in imposing elasticity to gluten structure. The mechanism involves the structural transitions between β-sheet and β-turns and is related to the long repeat regions of HMW-GS and their interactions. On the other hand, corn protein, zein, is relatively small protein and does not demonstrate viscoelastic properties at room temperature. However, α-zein was shown to form viscoelastic dough at moisture contents larger than 20% when hold and mixed at 35°C, which is above its glass transition temperature. Here, it is speculated that gliadin, which comprises significant portion of wheat gluten, is not only simply a filler imparting viscosity to wheat gluten, but also an important functional protein fraction that goes through structural transformation with addition of HMW-GS to the system. Therefore, it is hypothesized that, zein, which shows similarities to wheat gliadin in number of aspects, can attain viscoelastic properties at room temperature with addition of co-protein similar to that of HMW-GS in wheat gluten. Wheat and corn proteins were utilized in this study to investigate and compare their viscoelastic properties. Fundamental rheological techniques and Fourier Transform InfraRed (FT-IR) spectroscopic studies were performed to understand the structure-function relationship in these proteins. Improved viscoelastic properties were obtained for zein with addition of co-protein at room temperature. The transformation of gliadin with the addition of HMW-GS and glutenin was also shown. However, gliadin and zein were found to gain structural functionality through different mechanisms. In gliadin, structural transformation took place through transitions between β-sheet and β-turns. On the other hand, main transition in zein was found to be from α-helix to β-sheet.^

]]> Mehtap Fevzioglu Agriculture, Food Science and Technology|Engineering, Agricultural http://docs.lib.purdue.edu/dissertations/AAI3556200 http://docs.lib.purdue.edu/dissertations/AAI3556200 Wed, 22 May 2013 15:51:41 PDT Study abroad programs are formal educational courses provided by colleges and universities during which the student receives academic credits while studying in another country. There is a need for further research regarding the effects of study abroad in relation to career development. ^ This study examined near-term effects of a semester study abroad program on career self-efficacy, and attitudes regarding career plans, self-confidence, and international travel. The study group consisted of 369 undergraduate students enrolled in study abroad at The Pennsylvania State University during 2007 and 2008, who completed an initial career self-efficacy questionnaire, which was the Career Decision Self-Efficacy Scale-Short Form (CDSE-SF). Changes in questionnaire responses were assessed in 83 and 141 students who were surveyed both before and after an on-campus and study abroad semester, respectively. Statistical comparisons were based on rank scores of outcome variables. ^ Career self-efficacy measures in the initial survey were in general agreement with those reported in two other university studies and did not differ notably by gender, class level, major, or previous personal travel experience. However, a strong sense of conviction that study abroad was essential to career development was found to predict significantly higher scores on overall career self-efficacy and several subscales. ^ The major study finding was that highly significant improvements in feelings of self-confidence and ability and in enthusiasm for international travel occurred during the study abroad semester. ^ Another study finding was that no change in overall career self-efficacy was observed in relation to the study abroad experience, although marginally higher career self-efficacy scores were observed on the occupational information, planning, and problem solving subscales. Career self-efficacy is a construct that may not have application in measuring the impacts of study abroad on career development. ^ The findings of this study in regard to enhanced feelings of self-confidence and ability and enthusiasm for international travel could be useful to administrators in their efforts to promote study abroad and to students in deciding whether or not to participate in such programs.^

]]> John L Farris Education, Evaluation|Education, Higher Education Administration|Education, Multilingual http://docs.lib.purdue.edu/dissertations/AAI3556201 http://docs.lib.purdue.edu/dissertations/AAI3556201 Wed, 22 May 2013 15:51:41 PDT Recently, on-chip comb generation methods based on nonlinear optical modulation in ultrahigh quality factor monolithic micro-resonators have been demonstrated. In these methods, two pump photons are transformed into sideband photons in a four wave mixing process mediated by the Kerr nonlinearity. The essential advantages of these methods are simplicity, small size, very high repetition rates and sometimes CMOS compatibility. We investigate line-by-line pulse shaping of such combs generated in silicon nitride ring resonators. We demonstrate a simple example of optical arbitrary waveform generation (OAWG) from Kerr comb. We observe two distinct paths to comb formation which exhibit strikingly different time domain behaviors. For combs formed as a cascade of sidebands spaced by a single free spectral range (FSR) that spread from the pump, we are able to compress to nearly bandwidth limited pulses. This indicates high coherence across the spectra and provides new data on the high passive stability of the spectral phase. For combs where the initial sidebands are spaced by multiple FSRs which then fill in to give combs with single FSR spacing, the time domain data reveal partially coherent behavior. We also investigate the behaviors of a few sub-families of the partially coherent combs selected by a pulse shaper. We observe different coherence properties for different groups of comb lines. Furthermore we will discuss an ultrafast characterization techniques called dual comb electric eld cross correlation. This linear technique will provide both low optical power and broader bandwidth capability for full time domain characterization of OAWG from Kerr comb.^

]]> Fahmida Ferdous Engineering, Electronics and Electrical|Physics, Electricity and Magnetism|Physics, Optics http://docs.lib.purdue.edu/dissertations/AAI3556199 http://docs.lib.purdue.edu/dissertations/AAI3556199 Wed, 22 May 2013 15:51:40 PDT Two critical issues are of great concern in engineering education today: the increasingly broad requirements for 21^st-century engineers and the lack of effective instructional approaches needed to produce students who meet the requirements. However, pedagogical approaches in engineering have remained relatively unchanged for the last 40 years and less effort has been placed on implementing instructional approaches needed to achieve the desired learning outcomes in engineering education. This study proposed an instructional approach that combined project- and game-based learning, using a sustainable/Life Cycle Assessment (LCA) game-based project in first-year engineering education. This approach combined features of both GBL (motivation, engagement and learning through doing) and PBL (accumulating professional skills through real-world projects). A concurrent transformative mixed-method approach was utilized in this study to investigate (1) the changes in students' knowledge of sustainable development and their perceptions of their professional skill development following completion of the project; and (2) how students' perceptions of their motivation and engagement in the project were related to those changes. This study involved 240 first-year engineering students from two of the sixteen sections of an ENGR 131 course at a large Midwestern university. The findings revealed that students had a positive learning experience in the sustainability game project and the instructional approach of combining project- and game-based learning was an effective approach for teaching engineering content knowledge, improving students' professional skill development, and enhancing their learning motivation. Students' perceptions of their engagement decreased after the project and multiple reasons (e.g., low academic expectations) were identified for the decrease. This study provided evidence that this instructional approach was effective in engineering education and helped address the issues facing engineering education and educators today.^

]]> Jun Fang Education, Technology of|Education, Higher|Education, Vocational http://docs.lib.purdue.edu/dissertations/AAI3556198 http://docs.lib.purdue.edu/dissertations/AAI3556198 Wed, 22 May 2013 15:51:39 PDT Phosphorus (P) loss from agricultural fields to freshwater ecosystems is of increasing concern due to elevated soil P levels brought on by long term and excessive application rates of manure and commercial fertilizers. Both Bray P₁ and Mehlich-3 P (P_M3) soil tests are used in Indiana to make fertilizer recommendations and to limit manure application rates. The Mehlich-3 P Saturation Ratio (PSR_M3) has been proposed as an alternative to P_M3 and the ammonium oxalate degree of P saturation (DPS_OX) for assessing the risk of soluble P loss from soils. We assessed the correlations among agronomic soil test methods (P_M3 and Bray P₁), environmental soil test methods (soluble P: deionized water, DW; artificial rainwater, ARW; dilute salt extractable P, DSEP), ammonium oxalate P (P_OX), total P (TP), and P saturation methods from 565 Indiana surface soil samples. Significant correlations were found among the various STP methods evaluated, and Bray P₁ and P_M3 displayed the strongest coefficient of correlation (r = 0.93, p < 0.0001). Mehlich-3 P had stronger correlations with TP and P_OX compared to correlations between Bray P₁ and TP and P_OX, and their correlations were all highly significant ( p < 0.0001). Additionally, all soluble P forms were significantly correlated with Bray P₁, P_M3, and P_OX, and the correlations between Bray P₁ and all three soluble P measures were consistently greater than those between other soil test methods and the soluble measures. Significant correlations were found between P_M3 and PSR_M3 (r = 0.93, p < 0.0001) and between PSR_M3 and DPS_OX (r = 0.92, p < 0.0001), suggesting that PSR_M3 can be as effective as DPS_OX to identify soils with a greater potential to contribute bioavailable (not just soluble) P to surface and ground water. We conclude that both P_M3 and PSR_M3 can be integrated into more comprehensive P loss risk algorithms to mitigate elevated P concentration in surface and ground water. The PSR_M3 can be used as an alternative to P_M3 as it does account for extractable Al and Fe, the primary P sorbents in most soils. Although Bray P₁ is an appropriate soil test based on the data generated in this study, it would not be the most practical soil test as it is not considered a multi-element extraction in most states. Since P_M3 was strongly correlated with Bray P₁ and the benefit of using P_M3as a multi-element extractant from which the PSR_M3 can be calculated, it is probably the most practical test to use for both agronomic and environmental soil P assessment. We also evaluated the impacts of diets containing different amounts of DDGS and dietary fumeric acid on P excretion and P transformations during litter storage. Total P and phytate P were significantly (p< 0.0001) affected by dietary inclusion of DDGS; where DDGS inclusion of 20% decreased TP by 16, 15, and 16% for day 0, 7, and 14 of storage, respectively compared to commercial diets. Phytate P, on the other hand, was reduced by 38, 37, and 47% for day 0, 7, and 14 of storage, respectively. Overall, DDGS influenced the forms of P in poultry litter with phytate P being the most impacted. The inclusion of DDGS in poultry diets seems promising as it can potentially decrease the levels of phytate P in poultry litters, which is of may be of environmental significance as phytate P can desorb inorganic P in soils.^

]]> Branly Eugene Aeronomy|Water Resource Management|Environmental Sciences http://docs.lib.purdue.edu/dissertations/AAI3556197 http://docs.lib.purdue.edu/dissertations/AAI3556197 Wed, 22 May 2013 15:51:38 PDT The present study comparatively analyzes the philosophies of Martin Heidegger and Gilles Deleuze with regard to the theme of the nature of thought. Taking as a point of departure Deleuze's critique of what he takes to be a shift in Heidegger's thought from that of a violent to a peaceful one, this dissertation explores Deleuze's unique engagement with Heidegger, centering on the problem of thought and how it bears a central role in Deleuze's own philosophy of difference. Despite the fact that Deleuze and the Heidegger of the 1930's share a similar model of thought as an inherently violent activity that creatively discloses the new, the two philosophers derive vastly different implications with regard to the political. This dissertation also explores their contrasting orientations toward the relationship between philosophy, that is to say, thought which creatively discloses the world in a new way, and science.^

]]> Gregory Therel Esplin Epistemology|Philosophy http://docs.lib.purdue.edu/dissertations/AAI3556195 http://docs.lib.purdue.edu/dissertations/AAI3556195 Wed, 22 May 2013 15:51:37 PDT Equation of motion coupled cluster with single and double excitations (EOM-CCSD) method and time-dependent density functional theory (TD-DFT) are used to investigate electronic states of Diphenylmethane. The S₁ and S₂ potential energy surfaces with regard to two torsional angles are constructed. The TD-DFT and EOM-CCSD surfaces are qualitatively similar; however, both methods overestimate the experimentally observed S ₁–S₂ splitting of 123 cm^-1 by four to five times. ^ EOM-Spin-Flip-CCSD method accurately describes diradical states and is used to determine vertical and adiabatic singlet–triplet energy splittings in the substituted cyclobutadienes. The adiabatic singlet–triplet gaps decrease upon substituent addition, but the singlet states remain lower in energy. However, the results are affected by spin contamination of the reference state and deteriorate when an unrestricted HF reference is employed. ^ A MP2/cc-pVTZ intrinsic reaction pathway was constructed from a dialkynylcyclobuta-1,3-diene derivative undergoing thermal ring expansion to an eight-membered ring via either Cope-type-sigmatropic rearrangement or Bergman cyclization followed by ring opening. These findings raise questions concerning the ring coalescence and annealing model for carbon condensation and fullerene formation which does not include either of these reaction pathways. ^ The exchange-repulsion term or effective fragment potential (EFP), a first-principles based model potential developed as a nonempirical alternative to force-field based QM/MM methods, was parameterized in order to increase the speed of EFP calculations by a factor of ten. The expression for exchange-repulsion involves overlap and kinetic energy integrals between pairs of localized orbitals. These integrals make the exchange-repulsion the most computationally expensive part of EFP energy calculations in moderately sized systems.^

]]> Frank Lee Emmert Chemistry, Physical http://docs.lib.purdue.edu/dissertations/AAI3556196 http://docs.lib.purdue.edu/dissertations/AAI3556196 Wed, 22 May 2013 15:51:37 PDT Genomic imprinting has been studied extensively in higher plants and mammals where it plays a crucial role in development and has been linked to cancer and other diseases in mammals. The honey bee is one of the few invertebrate species in which genomic imprinting has been studied and could give new insights into parent-of-origin effects on behavior. The hypothesis tested was that parent-of-origin effects do exist in the honey bee and was done by using RNA-seq on two life stages of reciprocal crossed honey bees. Two different RNA-seq systems were used. The project was first done using the SOLiD 4 system, but validation of the results was poor due to a large number of false positives created from systematic and alignment biases that were not taken into account by the statistical methods used. The second system was the Illumina HiSeq 2 and the study was done using replicates and generalized linear mixed model statistics that could model and correct for systematic biases introduced during sequencing and alignment. The Illumina study showed that parent-of-origin effects do take place in the honey bee and the results were validated by sequencing PCR products of parent-of-origin effect transcripts using the Illumina MiSeq. The Illumina study showed that parent-of-origin effects are more evident in adult honey bees than in early larval stages, contrary to mammals and plants where the majority genomic imprinting takes place in early development. Regardless of life stage parent-of-origin effects in the honey bee are primarily biased towards maternal expression with the strongest maternal expression found in nuclear copies of mitochondrial genes or numts. The numts are not complete genes but gene fragments or pseudo-genes that are actively transcribed by the nuclear genome, which suggests a biological function and evolutionary selection for conserved maternal expression.^

]]> Christine Michelle Emore Biology, Entomology|Biology, Genetics http://docs.lib.purdue.edu/dissertations/AAI3556194 http://docs.lib.purdue.edu/dissertations/AAI3556194 Wed, 22 May 2013 15:51:36 PDT This study examines the impact of the school accountability laws "No Child Left Behind" and Indiana's Public Law 221 on Superintendents' perception of their relationship with the Teachers' Union Leader in their mandatory discussion meetings. Both school accountability laws contain provisions for the Indiana's Department of Education to take over poor performing schools if they fail to make Adequate Yearly Progress for five years. Two samples were constructed from Indiana's highest and lowest performing districts and the Superintendents in the two samples were surveyed. Results were compared in order to ascertain the impact of the sanctions on the low performing districts against those of the high performing districts. ^ There is much public discussion concerning the performance of public schools and the research, pro and con, spends considerable time discussing and measuring generalities. The review of the literature in this study argues for a new direction of study based on a framework of contracts as organizations and the importance of relational considerations by Smith and King (2009). It uses an instrument developed by Currall and Judge (1995) to measure trust between boundary role persons with additional questions, some of which are open-ended questions relating to specific information from each school district. The goal is to determine whether there is a difference between the high and low performing districts in Indiana through their Superintendents' perception of trust with their Teachers' Association Leader as well as through the impact of school accountability laws. ^ The survey revealed there is no statistically significant difference in the amount of trust between high and low performing school districts. It also found that high and low performing districts both view their relationships as slightly better than they were five years ago. However, when asked specifically whether school accountability laws had an impact on their relationships, low performing districts were statistically more likely to credit school accountability laws with having improved their relationships. Further qualitative analysis reveals those districts' Superintendents seemed to be able to leverage relationships to keep the nexus of stress outside their districts while developing a nexus of control within. The further study of these relationship skills would be beneficial.^

]]> Philip G Downs Education, Leadership|Education, Administration|Sociology, Industrial and Labor Relations http://docs.lib.purdue.edu/dissertations/AAI3556193 http://docs.lib.purdue.edu/dissertations/AAI3556193 Wed, 22 May 2013 15:51:35 PDT Given digital technology's expansion of environments that teaching and learning take place, this dissertation seeks to elucidate how both discourses and technologies themselves reconfigure the material and symbolic environments within higher education. To do so I explore the reciprocal relationship between various educational technologies, and the discourses surrounding their rationale and implementation. Additionally, I argue that current educational movements centered primarily on new technologies, are situated within broader ideological relationships among teaching, learning, notions of progress, and ultimately, concepts of "the good life." To better understand the environments created by digital technology, I introduce a media ecological analysis of the discourses and practices within higher education. I then move, more specifically, to critique the Do-It-Yourself (DIY) educational movement. I argue that despite the opportunities for positively transforming higher education, the DIY movement ultimately falls short given many of its proponents' treatment of technology as either neutral or as overly determined, and the treatment of teaching and learning as merely information transfer. ^ Furthermore, when operating within the ideological values of consumer capitalism, the DIY movement perpetuates unhealthy relationships between the personal and professional spheres. Chapter one situates this project within conversations surrounding the constitutive and material aspects of communication. Chapter two discusses concepts of neutrality and determinism, which ride throughout and fund many discourses surrounding education and technology. The former underestimates the power that technology has to reconfigure the symbolic and material realms, while the latter overestimates technologies ability to determine the course of human action. Chapter three introduces a media ecology approach to understanding discourse and technology. Here, I argue that media ecology provides a more versatile theoretical backdrop with which to highlight the reciprocal relationships between technology, discourse, and subsequent practices that emerge within the DIY movement. Finally, chapter four situates the previous chapters' findings within broader socio-cultural understandings of the relationship between education, work, and what is commonly articulated as "the good life." Here, I argue that against the backdrop of consumer capitalism, education becomes meaningful largely in conjunction with one's ability to secure a good job. However, notions of what constitutes a good job are invariably caught up in an individual's occupational productivity and subsequently, their economic capacity for consumption. Ultimately, this serves as a degenerate form of identity formation, which erodes more potentially ethical understandings of meaning and significance within the personal and professional spheres.^

]]> John Dowd Speech Communication|Language, Rhetoric and Composition|Education, Technology of|Education, Philosophy of http://docs.lib.purdue.edu/dissertations/AAI3556191 http://docs.lib.purdue.edu/dissertations/AAI3556191 Wed, 22 May 2013 15:51:34 PDT Positive and negative social interactions have implications for the psychosocial experiences of athlete burnout and well-being. Athlete burnout is a maladaptive cognitive-affective syndrome characterized by emotional and physical exhaustion, reduced accomplishment, and sport devaluation (Raedeke, 1997) whereas subjective well-being consists of positive affect and life satisfaction (Diener, Suh, Lucas, & Smith, 1999). Extant burnout theory (Coakley, 1992; Raedeke, 1997; Smith, 1986) suggests that positive (social support) and negative social interactions are salient to athlete burnout. Moreover, social support and negative social interactions may buffer and catalyze the stress–burnout and burnout–well-being associations, respectively, in sport. The purpose of this dissertation was to examine the concomitant associations of athlete perceptions of social support and negative social interactions with burnout and well-being when empirically-specified psychosocial variables were taken into account. Employing a cross-sectional design, Study 1 examined the associations of multiple types of teammate social support with athlete burnout and self-determined motivation in a sample of 235 collegiate athletes. Results showed perceptions of support satisfaction and perceived (but not received) support to be significantly associated with athlete burnout and self-determined motivation, a proximal well-being correlate. Adopting a longitudinal study design with a sample of 465 collegiate athletes, Study 2 examined social support and negative social interactions as potential moderators of the perceived stress-athlete burnout relationship when accounting for trait negative affect and athlete motivation. Results showed perceived stress and athlete social interactions to individually contribute to global burnout and exhaustion (but not reduced accomplishment and sport devaluation) across the competitive season. No moderation effects were supported. Using the same design and sample, Study 3 examined social support and negative social interactions as potential moderators of the athlete-burnout–well-being relationship when accounting for trait optimism. Results showed athlete burnout, social support, and negative social interactions to distinctly predict athlete well-being across the competitive season. No moderation was supported but the athlete burnout–well-being relationship was found to differ across athletes. Finally, in an exploratory effort, the potential existence of person-centered burnout profiles was explored in a sub-sample of 129 athletes. Similar profiles were found across time points that were largely characterized by similar scores on all burnout dimensions. Resulting profiles, which were distinguishable based on athlete social interactions, did not correspond with extant views on burnout development but did highlight a small sample of "burned-out" cases. Collectively, this dissertation showcases the importance of social support and negative social interactions to athlete burnout and well-being using both cross-sectional and longitudinal study designs and both variable- and person-centered data analytic approaches. Building on these findings, continued empirical examination of the relationships of sport-based social interactions with athlete burnout and well-being represents a fruitful research endeavor of important theoretical and practical benefit.^

]]> J.D DeFreese Health Sciences, Recreation http://docs.lib.purdue.edu/dissertations/AAI3556192 http://docs.lib.purdue.edu/dissertations/AAI3556192 Wed, 22 May 2013 15:51:34 PDT Purpose: This study examined: 1) relationships between spirituality, current health status and usage of a multi-faceted faith based community center (CC) by adults 18 years and over, and 2) physical activity (PA) behaviors and CC use among individuals over the age of 40 at baseline and 6 months. ^ Methods: Congregation members (n=155; Caucasian (n= 143, 92%); female (n=96, 62%); mean age 43 ± 13.5 years), completed a one-time online questionnaire on spirituality (SWB), current health status and CC usage. Individuals ≥40 years (Caucasian; female (n=18, 69%), mean age 54 ± 6.3 years) completed additional assessments on PA, social support, self-efficacy at baseline (Base-PAQ: n=26) and 6 months (6mos-PAQ: n=18), and participated in focus groups (n=6). ^ Results: 102/155 (66%) of respondents participated in the CC, with the track reported as the most desirable component of the CC in the cross-sectional study (57/ 102). The track also was favored (14/21) at the baseline physical activity questionnaire (Base-PAQ), while trails were favored (8/14) at the six month follow-up (6mos-PAQ). Spirituality levels of both samples were in the mid-ranges. Age, sex and CC participation were not related to spirituality. However, higher levels of education were related to higher spirituality scores at baseline. Better health status, better mental health, and higher levels of life satisfaction were related to increased CC participation in the cross sectional study. A majority (133/155) of those who were physically active were CC participants and reported higher duration of moderate PA and higher frequency of both moderate and vigorous PA. In addition, participants who were trying to lose weight were more likely to use the CC at baseline. The more often individuals used the CC, the more physically active they were at both Base-PAQ (significant) and 6mos-PAQ (approached significance). They also were more likely to participate in moderate and vigorous activity for longer duration at Base-PAQ and participate in vigorous PA more often at 6mos-PAQ. Neither social support nor self-efficacy predicted PA or CC participation at Base-PAQ or 6mos-PAQ. Based on qualitative results, PA barriers included environment, time, lack of motivation, priorities and physical health, while the primary motivator mentioned was health-related benefits. Personal networks and relationships already established at the CC gave participants more of a personal experience and encouraged them to be more active as well. ^ Conclusion: Results suggest that a faith-based facility has the potential to increase PA among its participants. However, further research with larger sample sizes and more diverse populations is needed. ^

]]> Angela DeMano Doehring Gerontology|Health Sciences, Public Health http://docs.lib.purdue.edu/dissertations/AAI3556190 http://docs.lib.purdue.edu/dissertations/AAI3556190 Wed, 22 May 2013 15:51:33 PDT Water is ubiquitous in many fields, especially geological and biological chemistry. Water is the medium in which most biological processes occur, and evidence suggests that water may actually play a key role in initiating and mediating these processes. To study the structure of water, particularly around hydrophobic molecules that may provide insight into the hydration of complex biological molecules like proteins, Raman vibrational spectroscopy is combined with multivariate curve resolution to produce a "hydration shell spectroscopy." This method extracts, from the raw data, the vibrational features arising from the solute and from perturbed solvent molecules that are characteristically different from the bulk. This method is employed to study, in aqueous solution, the formation of π-hydrogen with aromatics, a temperature-induced water structural transformation within the hydration shell of hydrophobic solutes, the formation and energetics of dangling OH bonds around such solutes, and the effect a neighboring carboxylate charge has on the hydrophobic character – and thus, the appearance of the previously mentioned phenomena – of the alkyl chains of the carboxylate. The results of these experiments offer exciting new information regarding these phenomena, and may be key steps in understanding more complex – and realistic – biological systems.^

]]> Joel Gregory Davis Chemistry, Physical http://docs.lib.purdue.edu/dissertations/AAI3556189 http://docs.lib.purdue.edu/dissertations/AAI3556189 Wed, 22 May 2013 15:51:32 PDT Spin-Transfer Torque Random Access Memory (STT-RAM) is a promising candidate for the next generation universal memory technology, with a combination of non-volatility, high endurance, high speed, and better scalability compared to existing memory technologies. The key building block of the operation of STT-RAM is the Magnetic Tunnel Junction (MTJ) device, which uses spin polarized currents instead of magnetic fields to read/ write magnetic bits. While the read process is largely determined by the charge current, the spin current is critical to the write process. This thesis presents a Non-equilibrium Green's Function (NEGF) based transport model for MTJ devices that allows us to model both charge and spin currents accurately. ^ Although there are several experiments describing the bias and switching behavior of MTJ, none of the existing theoretical models correctly provide quantitative agreement with experiments. Using our model, we show: (1) good agreement with diverse experimental measurements like resistance and spin torques; (2) provide simple explanation for bias dependences of the torques; and (3) propose an asymmetric STT device, which has the potential of switching in non-reciprocal way. Furthermore, we present an analytical expression for the spin current starting from the current operator expression; we discuss about the formalism of Non-Equilibrium spin current in the coherent transport regime and discuss initial results for a possible approach to developing a compact model for STT-RAM cell integrable with CMOS circuits.^

]]> Deepanjan Datta Engineering, Electronics and Electrical|Nanoscience http://docs.lib.purdue.edu/dissertations/AAI3556188 http://docs.lib.purdue.edu/dissertations/AAI3556188 Wed, 22 May 2013 15:51:31 PDT The emergence of ambient ionization mass spectrometry within the last decade with its minimal or no sample pretreatment has dramatically improved direct sampling measurements. With the introduction of the first ambient ionization techniques of desorption electrospray ionization (DESI) in 2004 and direct analysis in real time (DART) in 2005, there have been numerous sources described in the literature including low-temperature plasma (LTP) ionization sources. LTP ionization is notable for its simple design, low thermal temperatures, and low power and gas requirements that allow nondestructive sampling of compounds from sensitive surfaces such as human skin. This thesis details the development of improved LTP sources, the integration of these probes with miniature mass spectrometers, and the application of these sources to the quantitation of compounds. The first part of this thesis increases the utility of LTP sources by increasing the analyzable area that can be interrogated through the use of bundled source arrays. The sources have a larger sampling area that allows faster detection of each analyte, and selectivity towards the selected compounds is enhanced by adding reagents directly into the plasma stream. ^ The second part of this thesis integrates LTP sources with miniature mass spectrometers. This work was inspired by the idea of having a completely field portable mass spectrometer that is fully self contained without the need for external gas cylinders or solvents. The miniaturization of these probes allows for gases other than helium to be used with lower power requirements which simplifies the instrumentation. It is shown that a miniature mass spectrometer equipped with LTP probes can be used to detect explosives in situ without the need of solvents or gas cylinders. Unlike DESI or spray techniques, LTP-MS systems benefit most from probe-surface sampling angles ranging from perpendicular to geometry independent (GI) configurations. The optimal sampling angles and heating of the surface to improve detection of compounds is demonstrated. ^ The final chapter details the application of LTP-MS to the semi-quantitation of volatile and semi-volatile compounds. A fast and direct method is presented for the analysis of semi-volatile fragrance compounds without sample pretreatment. LTP is used to perform high-throughput analysis, determine limits of detection (LODs), and obtain semi-quantitation information on various surfaces. A peltier cooling device is used to enhance the retention time of compounds on a surface. The method allows the detection and quantitation of semi-volatile compounds in the low pg ranges with a commercially available cleaning product after 1 min of being applied to a vinyl tile surface.^

]]> Jon King Dalgleish Chemistry, General|Chemistry, Analytical http://docs.lib.purdue.edu/dissertations/AAI3556187 http://docs.lib.purdue.edu/dissertations/AAI3556187 Wed, 22 May 2013 15:51:30 PDT In 2010, the Indiana Department of Education stopped providing schools supplemental money to be allocated for individual school Professional Development funds. This forced building level administrators to develop creative means to provide professional development opportunities. During this same period of time, the Indiana Department of Education advocated for an increased emphasis on teacher evaluation and specifically, tying teacher evaluation to student performance. Teacher collaboration and data-driven instruction have often been cited as "best practices" in terms of school effectiveness; however, very little research has been conducted showing their effect on teacher efficacy. The purpose of this research was to evaluate the usage of Collaboratively Developed Common Formative Assessments as an alternative means to provide professional development and improve teacher efficacy. ^ A quantitative study was utilized to measure the effect Common Formative Assessments would have on teacher self-efficacy. Pre and Post-test survey data was collected to measure and compare the changes that occurred between two groups of teachers: Treatment group (teachers utilizing Common Formative Assessments) and control group (teachers that utilized traditional summative assessments). In this study neither group experienced a statistically significant change in their self-efficacy score; however, it was interesting to note that in this population, while the treatment group's self-efficacy increased, the control group's self-efficacy score decreased after a year of using only traditional summative assessments. Further research with a larger population of teachers should be done to determine whether this decline was an isolated incident. ^

]]> Scot D Croner Education, Tests and Measurements|Education, Leadership|Education, Administration http://docs.lib.purdue.edu/dissertations/AAI3556185 http://docs.lib.purdue.edu/dissertations/AAI3556185 Wed, 22 May 2013 15:51:29 PDT Although Aves is one of the best-studied taxa, much remains to be learned about marsh bird populations. Understanding species-environment relationships for marsh birds is complicated by the low detection probabilities of many species and the challenges associated with sampling wetland habitats. I evaluated habitat relationships at multiple spatial scales for a marsh passerine, the Swamp Sparrow (M. g. georgiana), in the Great Lakes Region. At the local scale, I monitored breeding Swamp Sparrows at restored and natural marshes and assessed the degree to which habitat attributes influenced nesting success. I hypothesized that nesting success would be lower in restored marshes because of shallower water depths and differences in vegetation composition that may increase nest site accessibility to predators or alter food resources. The daily nest survival rate varied as a quadratic function of date, with survival being highest in the middle of the nesting season. Pooled daily nest survival rates were 0.917 (SE = 0.010) for the restored marshes and 0.937 (SE = 0.009) for the natural marshes. The nest success rate of 0.11 for restored marshes was significantly less than the nest success rate of 0.18 in natural marshes. All four marshes appeared to function as demographic sinks, although there were large uncertainties in estimated adult and juvenile survival rates. ^ At the patch or wetland scale, I surveyed 21 wetlands using the North American Marsh Bird Monitoring Protocol to compare detection probabilities, species densities, and marsh bird community composition at restored and natural marshes. I expected that detection probabilities and community composition would be generally similar, although I expected slightly fewer wetland species at restored marshes because of lower water levels. I recorded 35 wetland-associated species, comprised of 30 species at natural marshes and 31 species at restored marshes. I estimated detection probabilities for the Swamp Sparrow, Common Yellowthroat (Geothlypis trichas), and Song Sparrow ( Melospiza melodia). Detection probabilities differed among species but did not differ between restored and natural marshes. Densities of these three species were similar in natural marshes; however, Swamp Sparrows trended toward lower densities in restored marshes. Species richness and similarity and diversity indices suggested that the breeding bird communities were similar at restored and natural marshes. ^ At the population scale, I modeled Swamp Sparrow abundance and evaluated how the choice of spatial and temporal scales used to aggregate Breeding Bird Survey (BBS) data influenced model fit and performance. I hypothesized that Swamp Sparrow abundance would be negatively influenced by the amount of cropland and medium- and high-density development, road density, and temperature, and be positively influenced by the amount of wetland area, stream density, and winter precipitation. I expected that models based on intermediate spatial data aggregation scales (e.g., 5-stop or 10-stop segments) would exhibit the highest concordance with environmental variables but that route-scale models would exhibit the best performance. All top-ranked models of Swamp Sparrow abundance contained a measure of proximal wetland land cover. The highest concordance between wetland land cover and Swamp Sparrow abundance occurred at small rather than intermediate spatial extents, ranging from 200 m to 400 m from BBS stops, segments, or routes. Contrary to my expectations, road density, the amount of cropland, and the amount of high- and medium-density development did not exhibit a strong negative effect on Swamp Sparrow abundance. The average temperature recorded during each breeding bird survey influenced Swamp Sparrow abundance within a single year, but this effect disappeared when counts were summed over multiple years. Winter precipitation positively influenced Swamp Sparrow abundance aggregated for 5-stop and 10-stop segments, but was not a significant predictor in route-scale models. Route-scale models exhibited the best performance, with Spearman's rank coefficients between observed and predicted mean values averaging 0.47. Correlation coefficients for models based on 5-stop and 10-stop segments ranged from 0.26 to 0.38. My findings confirm that Breeding Bird Survey data may be useful for monitoring and modeling the populations of abundant marsh birds; however, greater uncertainty may be present in marsh bird models based on fine spatial and temporal data aggregation scales. (Abstract shortened by UMI.)^

]]> Kathleen Elizabeth Coates Agriculture, Wildlife Conservation|Biology, Ecology|Natural Resource Management http://docs.lib.purdue.edu/dissertations/AAI3556186 http://docs.lib.purdue.edu/dissertations/AAI3556186 Wed, 22 May 2013 15:51:29 PDT In the United States (U.S.) over the past 30 years, the number of medical procedures using radiopharmaceuticals has increased 500% along with a similar increase in the per capita effective dose. The Bureau of Labor statistics (BLS) reported from 1999 to 2010, that the numbers of nuclear medicine technologists have increased by nearly 200%. Therefore, if the patient dose has increased, there is potential for the dose from radiation exposure to workers in the nuclear pharmacy to increase. The dose that is of particular concern is the dose to the extremities, especially the fingertips. In addition to the risk of radiation exposure, workers in nuclear pharmacy are at risk for musculoskeletal disorders, especially to the upper limbs and low back because of the design of nuclear pharmacy workstations. ^ The first major goal of this study was to investigate the interaction of the workstation design, radiation exposure, risk of musculoskeletal disorders, and individual anthropometry using the technique of video exposure monitoring (VEM) with a real-time extremity dosimeter. Shielding and good work practices are designed to limit the annual radiation exposure to the extremities to less than 500 millisievert (mSv) per the National Commission on Radiation Protection (NCRP). However, individuals in nuclear pharmacy laboratories do not always follow these practices. Because of this, the second major goal of this study was to identify specific work practices in the nuclear pharmacy laboratories using the principle of "As low as reasonably achievable" (ALARA) that can cause increased radiation exposure to the extremities. The third major goal was to define a potential relationship between anthropometric variations and radiation exposure to radiopharmaceuticals and to identify worker tasks that can cause musculoskeletal stress to the body, thereby affecting worker efficiency and productivity. The fourth goal was to recommend a new workstation design that could reduce radiation exposure and reduce the risk of musculoskeletal disorders. ^ The radiation exposure assessment in Phase 1 of this study showed that using optimal practices minimizes dose but it is not 0. The greatest exposure to the extremities using optimal work practices is the capping and recapping of the needle and miscellaneous activities. Using optimal work practices versus non-optimal work practices was found to take up to twice the amount of time on average to perform the entire protocol for inexperienced workers. However, the integrated exposure to radiation was using non-optimal work practices was approximately 7 times the exposure of when using optimal work practices. When the job was broken down into tasks, there were four distinct elements (practices) per job cycle. The optimal versus non-optimal work practices shows that the time to perform each task element was longer by factors of 1.3, 1.8, 1.8, and 2.1 respectively. The exposure to radiation using non-optimal work practices was more than when using optimal work practices for Task element 1, 2, 3, and 4 by factors of 5.7, 5.0, 16.9, and 5.0, respectively. This indicates that optimal work practices should be a part of the training of workers in the nuclear pharmacy. ^ Aspects of the current workstation are designed to minimize radiation exposure, however, these design aspects that reduce radiation exposure may increase the risk of musculoskeletal disorders. However, designing purely for minimization of musculoskeletal disorders may put the worker at risk of exposures beyond the occupational limit to the extremities of 500 mSv (50 rem) in a year. This study concluded from the analysis of the dimensions of the L-block relative to anthropometry, the radiation exposure assessment, and ergonomic assessment that the current L-block design may influence excess radiation exposure and the risk of musculoskeletal disorders. Therefore, a redesigned workstation that uses anthropometry to account for individual variations is warranted. Based on the results from this study, the new workstation should still be in the form of an L-Block but be adjustable in height and width so that it fits 90% of the United States work population. A redesigned workstation has the potential to reduce radiation exposure and lessen the risk of musculoskeletal disorders. (Abstract shortened by UMI.)^

]]> Sandra Suzanne Cole Health Sciences, Occupational Health and Safety|Health Sciences, General http://docs.lib.purdue.edu/dissertations/AAI3556184 http://docs.lib.purdue.edu/dissertations/AAI3556184 Wed, 22 May 2013 15:51:28 PDT Very limited experimental test data are available on the response of pile groups under the combined action of vertical and lateral loads. In practice, the loads applied on piles are often a combination of both vertical and lateral loads. In addition, piles are often arranged in groups, and the behavior of a pile group may differ substantially from that of a single pile. In this research, tests were performed on model pile groups subjected to both axial and lateral loads in order to evaluate the effects of pile-pile interaction in pile groups and to study the influence of axial loads on the lateral load response of pile groups in sands. The model pile groups tested consisted of 2×2, 1×2, and 1×3 piles. The model piles were driven into sand samples prepared at different densities using a large pluviator. The piles were then connected by a solid steel pile cap placed above ground level. The axial load (base and shaft) for a pile cap displacement of 10% of the pile diameter was first obtained from axial load tests. For all the model pile groups tested in dense sand, the group efficiency was a little less than unity, while in the case of the pile groups tested in medium dense and loose sand values of group efficiency higher than one were measured. The results of the lateral pile load tests were presented in terms of the lateral load-pile head displacement response of the model pile groups, the load experienced by the individual piles in the groups, and the bending moment profiles of the individual piles. The lateral load carried by each pile was obtained from strain gauges that were attached to the shaft of the piles 10cm below their head. The results showed that the leading piles experienced larger loads and bending moments than those experienced by the trailing piles due to the more intense pile-pile interaction. The combined load tests were performed for axial loads of 0% (pure lateral load), 25%, 50%, and 75% of the axial loads of the pile groups corresponding to a settlement of 10 % of the model pile diameter. The results of the combined load tests demonstrated that the bending moments and lateral deflections of the pile head increases substantially in the presence of axial loads with antifriction devices which provide minimal restraint to the lateral movement of the test piles.^

]]> Yoon Seok Choi Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI3556182 http://docs.lib.purdue.edu/dissertations/AAI3556182 Wed, 22 May 2013 15:51:27 PDT Flying animals with flapping wings exhibit extraordinary ability to control their flight, they demonstrate rich repertoire of agile maneuvers but remain surprisingly stable during hover. This thesis worked towards an integrative understanding of such biological flight system based on multidisciplinary and collaborative efforts from engineers and biologists. I first studied the open-loop flight dynamics by investigating the effect of body movements on the changes in flight forces/torques, deriving analytical models for the flight dynamics at hover. Based on these models, the flight was found to be passively unstable in both longitudinal and lateral dynamics, as consistent with previous simulation studies. The body yaw rotation was then found to create substantial damping (flapping counter torque, FCT) during rapid turning maneuvers (saccades) in flapping fliers ranging in size from fruit flies to large birds. Our FCT model predicts that isometrically scaled animals experience similar damping on a per-wingbeat time scale, resulting in similar turning dynamics in wingbeat time regardless of body size. It was also found that in fruit flies, the damping due to FCT can account for a large part of the deceleration during saccades, but active yaw torque from asymmetric wing motion is required to terminate body rotation. Finally, I studied the active control strategy used by hawkmoth in exquisitely controlled pitch maneuvers. The realistic wing motions during the maneuver were recreated in a dynamically scaled wing model to experimentally determine the flight force/torque. The control strategies were then identified by comparing open-loop dynamics to the observed closed-loop dynamics, where it showed that feedback control based on pitch angle and angular velocity is essential to stabilize the flight.^

]]> Bo Cheng Engineering, Mechanical|Biophysics, Biomechanics http://docs.lib.purdue.edu/dissertations/AAI3556181 http://docs.lib.purdue.edu/dissertations/AAI3556181 Wed, 22 May 2013 15:51:26 PDT The false discovery rate (FDR) is a widely used error measure in multiple testing. Adaptive FDR procedures, incorporating a conservative estimator of the proportion of true null hypotheses, are usually more powerful than their non-adaptive counterparts. However, their performances depend critically on the test statistics having continuous distributions with very restrictive dependencies. Recent genomic sequencing technologies such as microarray and next-generation sequencing have generated massive data sets from which statistical analyses produce discrete test statistics and continuous test statistics bearing unknown and strong dependency. These two features have been known to have adverse effects on existing FDR procedures. Towards this end, better adaptive FDR procedures for discrete and for dependent continuous test statistics are needed. For multiple testing based on p-values from discrete test statistics whose null distributions dominate the uniform distribution, new estimators of the proportion of true null hypotheses and of the FDRs of one-step multiple testing procedures (MTPs) are proposed. Further, to better estimate the FDRs of one-step MTPs when testing normal means under dependence, a (uniformly) consistent estimator of the proportion of nonzero normal means, when the test statistics follow a joint normal distribution whose known covariance matrix represents strong dependencies of a certain type, has been developed. Improved performances of these new estimators have been justied both theoretically and empirically.^

]]> Xiongzhi Chen Statistics http://docs.lib.purdue.edu/dissertations/AAI3556180 http://docs.lib.purdue.edu/dissertations/AAI3556180 Wed, 22 May 2013 15:51:26 PDT In microelectronic assemblies, the fatigue life of solder joints is a critical element of the overall product reliability. Fundamental to understanding the fatigue life of solder joints is the creep behavior of the solder alloys. This is since the alloys experience homologous temperatures ranging from 0.4-0.8T _m during field use conditions. Specifically, the popular Pb-free candidates, SnAgCu solder alloys, evolve in their microstructure, and as a result in their mechanical behavior, with time under field use conditions. The challenge in developing predictive models of the mechanical behavior of these solder joints is twofold. The first challenge is in developing microstructural descriptors to characterize the evolution of the microstructure in these alloys under conditions that induce aging. The second challenge is in connecting the microstructural evolution to a corresponding evolution in the mechanical behavior. ^ Traditionally, constitutive laws of creep deformation describe a relation between stress, strain, strain rate and temperature at a given "state" of the material. Hence, material models for an alloy that is subjected to continuos evolution in microstructure can only be indirectly characterized using traditional viscoplastic constitutive laws since the connection to microstructure has to be made through the state variables. Furthermore, as the solder joint size shrinks, pad finish, reflow cooling rate, coarsening due to faster diffusion become additional critical factors in determining the creep behavior. During reflow, the joints undergo non-equilibrium solidification with Sn undercooling considerably "locking" the Ag₃Sn and Cu₆Sn₅ precipitates in the matrix. With time, the microstructure evolves into a thermodynamically stable state. The primary force of phase transition/evolution is the "diffusion potential" between the meta-stable (unaged) state to a stable (aged) state. ^ The research described in this thesis is based on the hypothesis that there exists a relation between the microstructure and the mechanical behavior observed in SnAgCu solder alloys. As a preliminary effort to the main thrust of the thesis, the mechanical behavior variation of the solder joints is studied as a function of surface finish, reflow cooling profile and alloy composition. Diffusion being the critical factor for secondary phase evolution, microstructures were next analyzed as a function of aging. Specifically, two microstructural descriptors are considered in this study: the size of the Ag₃Sn inter metallic particles and the size of the βSn dendrite. Three dimensional phase growth and coarsening of the microstructure is extensively characterized with the help of stereological techniques applied on two-dimensional micrographs. The thesis lastly focuses on addressing the effect of mechanical behavior of SnAgCu alloys as a function of the microstructure by developing functions to relate the creep model parameters to underlying microstructural parameters. The versatility of the creep model is demonstrated via the ability to predict creep behavior of hypo-eutectic SnAgCu joints with an unknown process, design and aging history, but with known microstructural state. For this work, more than one hundred and forty eight mechanical creep and steady state strain rate experiments were performed apart from at least around thirty six metallographic experiments that involved the use of electron microscopy techniques. The developed microstructurally adaptive creep model is validated rigorously in three ways. First to demonstrate the model's ability to fit to data used in developing the model, second in predicting both the microstructure as well as the creep behavior at aging conditions not used to develop the model and lastly by predicting the behavior of a solder joint consisting of a different Ag composition relative to those used for model development. In all three cases, the predictions of creep behavior are shown to be in statistical agreement with the experimental observations.^

]]> Sri Chaitra Jyotsna Chavali Chemistry, Inorganic|Engineering, Mechanical|Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI3556179 http://docs.lib.purdue.edu/dissertations/AAI3556179 Wed, 22 May 2013 15:51:25 PDT We spectroscopically resolved the reduced state of the primary electron acceptor of Photosystem I, A₀, in its lowest energy Q_y region for the first time without the addition of chemical reducing agents and without extensive data manipulation. To carry this out, we used the menB mutant of Synechocystis sp. PCC 6803 in which phylloquinone is partially replaced by plastoquinone-9 in the A₁ sites of Photosystem I. The subsequent long lived A₀^- state is most probably due to dysfunctional A₁ sites. This conclusion is inferred based on the monitored A₀^- lifetime of ∼22 ns that is typical of charge recombination between A₀ ^- and P₇₀₀⁺. The maximum bleaching (A ₀^- - A₀) was found to occur at 684 nm with a corresponding extinction coefficient of 43 mM^-1 cm ^-1. The data show evidence of an electrochromic shift of an accessory chlorophyll pigment, suggesting that the latter Q_y absorption band is centered around 682 nm. ^ The study of electrochromic shift in the P₇₉₈⁺ of Heliobacterium modesticaldum also shed lights on its RC core composition: we propose the first spectral evidence that, while the A ₀ pigment is Chl a, the accessory pigment is BChl g. Femtosecond spectroscopy reveals that energy equilibration within the BChl g antenna pigments occurs in 0.67 ps, trapping of the energy by the special pair takes place in ∼5 and ∼20 ps and that the resulting A₀^- has a lifetime of ∼450 ps. ^ With similar kinetics for energy and electron transfers, the green sulfur bacteria Chlorobium tepidum has the advantage that its special pair, P₈₄₀, can be clearly differentiated from the main antenna absorption band at low temperature. Such unique feature permitted us to observe for the first time the rapid electron transfer from the directly excited special pair (BChl a) to the primary electron acceptor (Chl a) and infer that the intrinsic charge separation in the RC occurs in <200 fs. ^ We also confirm that the slow heme reduction in the dimeric cytochrome b₆f complex, occurring in ∼150 s, involves both, the heme b_n and b_p, simultaneously. Under complete reduction of the hemes, the b₆f complex most probably undergoes conformational changes. This conclusion is supported by the consequent electrochromic shift of the embedded Chl a that is opposite, in direction, to the predictions based on the current oxidized b₆f complex structure.^

]]> Adrien Alexis Paul Chauvet Chemistry, Biochemistry|Physics, General|Biophysics, General http://docs.lib.purdue.edu/dissertations/AAI3556149 http://docs.lib.purdue.edu/dissertations/AAI3556149 Wed, 22 May 2013 15:51:24 PDT Gammaherpesviruses (γHV) cause multiple cancers in immunocompromised individuals. Due to the species' specificity of human γHV, which include Epstein-Barr and Kaposi's sarcoma herpesviruses, we use murine gammaherpesvirus 68 (MHV68) as an animal model to study these viruses in each stage of the viral life cycle. The goal of this research is to define the role of cytokines involved in the innate immune response in control of lytic infection and reactivation from latency. One of these cytokines is TNFα, which is involved in death receptor signaling. To test the hypothesis that MHV68 regulates TNFα-induced cell death, we treated infected 3T3 cells with TNFα either alone or in combination with cycloheximide (CHX). In uninfected cells, TNFα simultaneously activates pro-survival and apoptotic signaling pathways, resulting in cell activation but not cell death. CHX blocks NF-κB-dependent synthesis of pro-survival proteins, causing apoptosis when administered with TNFα. We found that cells infected with MHV68 for 8 hours underwent rapid TNFα-induced cell death even in the absence of CHX. We also found that a replication-competent virus is necessary for the cell death, suggesting that pro-survival pathways are blocked by early steps in MHV68 infection. We show that anti-apoptotic pathways are intact by demonstrating that the NF-κB subunit p65 translocates to the nucleus and functions as a transcription factor. We have also identified a modification of the anti-apoptotic protein cellular FLICE-like inhibitory protein Raji (cFLIPR) during MHV68 infection, which, we hypothesize, predisposes the infected cells to death upon TNFα treatment in a novel way. To date, no other viruses have been shown to modify cFLIP to induce cell death in this manner. Another innate immune response cytokine known to slow the spread of infection is IFNαβ. We found that mice lacking receptors for IFNαβ (Ifnar1^-/-) were able to clear MHV68 infection but experienced a significant increase in reactivation of latent virus ex vivo. To determine which specific cell types respond to IFNαβ to control reactivation in vivo, we used tissue-specific Cre-recombinase-transgenic mice to delete Ifnar1 only in macrophages. Macrophages are a known latency reservoir for MHV68, and this technique allowed us to target the role of macrophages and only in macrophages. Macrophages are a known latency reservoir for MHV68, and this technique allowed us to target the role of macrophages and IFNαβ signaling during latency. Macrophage-specific Ifnar1^-/- mice were infected with MHV68 and viral reactivation assessed at 16 days post-infection. We found that removal of IFNAR1 function from macrophages causes a 10-fold increase in reactivation over wild-type in peritoneal cells, as well as a 2.5-fold increase in splenocytes. These data indicates an essential role for IFNαβ signaling in macrophages to control MHV68 reactivation. Determining the role of IFNαβ signaling and the specific cell types that are important for controlling γHV reactivation from latency, as well as understanding how MHV68 modulates cell death pathways, will help guide future research into therapeutics for these diseases.^

]]> Rachel Suzanne Beard Biology, Cell|Biology, Virology|Health Sciences, Immunology http://docs.lib.purdue.edu/dissertations/AAI3555472 http://docs.lib.purdue.edu/dissertations/AAI3555472 Wed, 22 May 2013 15:51:23 PDT Symbolic analysis is an enabling technique that improves the effectiveness of compiler optimizations, by detecting numeric properties of program variables or relationships between the variables, and by exposing such properties to compiler optimizations. Expressing the abstract values of program variables in terms of value ranges and analyzing expressions using the ranges are one of the most advanced symbolic analysis techniques to date. Previous work on this symbolic analysis has not fully explore its possibility in terms of coverage and utilization. This thesis aims at investigating possible advances in this symbolic analysis by providing two techniques, interprocedural symbolic range propagation and array value propagation. The two techniques were developed based on the symbolic analysis engine which utilizes the value ranges of variables. Interprocedural symbolic range propagation enables whole-program analysis for propagating scalar value ranges, and array value propagation uncovers value properties of array variables. The evaluation result shows that the two techniques increase the effectiveness of automatic parallelization and provide better compile-time knowledge so that the compiler improve the code quality using the knowledge.^

]]> Hansang Bae Engineering, Computer|Computer Science http://docs.lib.purdue.edu/dissertations/AAI3556148 http://docs.lib.purdue.edu/dissertations/AAI3556148 Wed, 22 May 2013 15:51:23 PDT The estimation of long-memory processes has been studied from different perspectives: non-parametric, parametric and bayesian. From a general point of view, we consider a stationary gaussian process with explicit parametric spectral density. Under some conditions on its autocovariance function, we defined a GMM estimator that satisfies consistency and asymptotic normality, using previous results on ergodicity and the Breuer-Major theorem. This result is applied to the joint estimation of the drift and Hurst (H) parameters of a stationary Ornstein-Uhlenbeck (fOU) process driven by a fractional Brownian motion. The asymptotic normality of its GMM estimator applies for any H in (0,3/4), but using Malliavin calculus techniques we extend it to the case H=3/4. This parametric technique is also illustrated with the long-memory estimation of the fractional Gaussian noise. ^ From a bayesian perspective, the estimation of long-memory parameters is more related to filtering problems. As an application of this particularity, we performed a reconstruction of the Northern Hemisphere (NH) temperature anomalies over the past millennium by combining both the temperature proxies and external forcings while taking the possible long memory features of the involved stochastic processes into account, using a Hierarchical bayesian model. Our reconstruction is based on two linear equations, one in which the unobserved temperature series is linearly related to the three main external forcings, and another in which the observed temperature proxy data (tree rings, ice cores, and others) which is linearly related to the unobserved temperatures. Uncertainty is modeled through a long-memory fractional Gaussian noise. Our MCMC results give us reconstructions of the past unobserved land-air temperature anomalies and combined land-and-marine anomalies over the period 1000-1899, together with a precise description of the reconstruction uncertainty in the form of an empirical posterior distribution for the temperature series.^

]]> Luis Alberto Barboza Chinchilla Applied Mathematics|Statistics|Paleoclimate Science http://docs.lib.purdue.edu/dissertations/AAI3555234 http://docs.lib.purdue.edu/dissertations/AAI3555234 Wed, 22 May 2013 15:51:22 PDT The purpose of this study was to focus on how soil moisture and vegetation heterogeneity can play an important role on surface processes such as atmospheric feedback under drought and non-drought conditions. The study also aims to improve land surface representation climatology in terms of single and coupled modes of land surface and weather forecasting models. The general methodology was applied to evaluate the performance of the offline high resolution Noah land surface model (version 3.1) versus the Noah land surface model with the photosynthesis-based Gas exchange Evapotranspiration Model (Noah GEM) using different land types such as forest and agricultural areas (i.e., the Niwot Ridge Ameriflux site, USA and the Avignon CarboEurope site, France) ^ The coupled model Weather Research - Advanced Research Version (ARW ver. 3) was also employed to help understand the coupled processes between biochemical plant physiology, soil moisture, and atmosphere. Three cases were conducted: 1) an LLJ (low level jet) event observed on 3 June 2002 over the IHOP (International H₂0 Project) field experiment, 2) a severe drought from 11-19 June 2006 over the Southern Great Plains region (SGP); and 3) deep and shallow convection from 10-13 June 2007 over the CLASIC (Cloud and Land Surface Interaction Campaign) SGP region. Field experiment and aircraft data from the Ameriflux and CarboEurope site, IHOP, and the CLASIC campaign were used to calibrate and validate the models. All three hypotheses have been answered showing 1) The improved land surface initial conditions (soil moisture and temperature) using a high resolution land data assimilation system (HRLDAS) will lead to enhanced predictions of summer daytime and nighttime mesoscale forcing under both weak and intense synoptically-driven cumulus convection conditions. 2) Vegetation transpiration is more efficient than soil evaporation in transporting moisture from the land surface to the atmosphere during convection simulations. 3) Interactions between local and large-scale land surface heterogeneity can affect regional convection in the Southern Great Plains for both IHOP and the CLASIC field phase (June 2002 and June 2007). ^ This study provides some of the first results highlighting land surface-vegetation-soil moisture-atmospheric feedback as an important factor not only for daytime processes but also for improved simulation of early morning and nighttime convection. Also the improved Noah land surface model predicted more accurate energy flux, cloud radiation, rainfall, soil moisture, and soil temperature during extreme drought conditions and shallow cumulus convection. Future works include the use of finer-scale data assimilation and long-term soil moisture climatology to improve model performance. Additional plant physiological biochemistry formulations need further evaluation. The impact of convection triggers and vegetation transpiration on deep convection also need further investigation.^

]]> Umarporn Charusombat Geodesy|Environmental Sciences http://docs.lib.purdue.edu/dissertations/AAI3555232 http://docs.lib.purdue.edu/dissertations/AAI3555232 Wed, 22 May 2013 15:51:21 PDT The study of bipedal posture on rigid and compliant surfaces is of broad interest to neuroscience, cognition, and biomechanics. On one hand changes in the neuromuscular system due to disease or old age can lead to characteristic postural fluctuations and on the other hand training individuals on rigid and moving surfaces can improve balance and reduce the propensity to fall which is a major determinant in quality of life for aging populations. This thesis focuses on how ideas from nonlinear dynamics of reduced order dynamical systems can lead to better methods for analyzing experimental postural data to help explain postural behavior in a number of settings. First, an overview of the importance of studying postural dynamics is presented, followed by a literature review of the prior signal analysis and modeling works performed. Next, a signal analysis method using wavelet transforms to resolve postural fluctuation data about a stable equilibrium into several timescale components is discussed. Following this, the bifurcations of the upright equilibrium on a rigid surface are investigated using a simple inverted pendulum model. In addition, the presence of limit cycle behavior occurring in experimental postural data from subjects with a neuromuscular disorder are investigated. After this, the nonlinear dynamics and bifurcations of posture on a compliant surface are studied by coupling the previous model to a single degree-of-freedom balance board. The analysis of posture of a person standing on a balance board is extended to understand how a time delayed feedback on the balance board will alter stability the stability of posture. The thesis concludes with a summary of the key findings of this work and possible future directions.^

]]> James R Chagdes Engineering, Mechanical|Biophysics, Biomechanics http://docs.lib.purdue.edu/dissertations/AAI3555233 http://docs.lib.purdue.edu/dissertations/AAI3555233 Wed, 22 May 2013 15:51:21 PDT The human body experiences both internal and external forces on a daily basis. External forces range from ground reaction forces to traumatic events like head impacts, while internal forces are exerted on various tissues of the body by actions such as the constriction of muscle tissue, the passive stretch of connective tissues, and fluid pressurization in internal organs. The mechanical behavior of the numerous tissues of the body and their native mechanical environment are therefore tremendously important to understanding the structure and function of tissues that experience both internal and external forces. Noninvasive imaging techniques like magnetic resonance imaging (MRI) allow for high-contrast visualization of the morphology of most soft tissues. Additionally, various quantitative MRI techniques permit the characterization of tissues beyond just a qualitative evaluation of structure, including correlation with biochemical content and direct measurement of mechanical behavior. Among these, displacement encoding with stimulated echoes (DENSE) and similar techniques permit the measurement of displacements at each pixel of interest. This dissertation centers on the measurement of displacements under applied loading with MRI, or dualMRI. First, motivation is established for the development of a noninvasive imaging tool for the assessment of mechanical behavior of soft tissues, especially articular cartilage. Quantitative MRI techniques are discussed in the light of detecting cartilage damage, including assessment of its mechanical behavior. The dualMRI technique is then validated and demonstrated on a high-field research MRI system. Then, dualMRI is applied to characterize the changes in mechanical behavior after cartilage defect and with a tissue engineering implant within animal joints. Finally, the dualMRI technique is translated to use on a clinical MRI system, where it is validated and demonstrated in an ex vivo intervertebral disc section. The dissertation concludes with a discussion of the in vivo applications of dualMRI and, in particular, towards the measurement of displacements and strains within the tibiofemoral articular cartilage of a living human subjects.^

]]> Deva D Chan Engineering, Biomedical|Health Sciences, Radiology|Biophysics, Biomechanics http://docs.lib.purdue.edu/dissertations/AAI3555231 http://docs.lib.purdue.edu/dissertations/AAI3555231 Wed, 22 May 2013 15:51:20 PDT Most effective teaching methods actively engage students in the process of learning. Active engagement requires individual attention of teachers for each student group or student, which is highly time and resource intensive and almost impossible to implement in most schools in most disciplines. ^ In the last four decades, many intelligent tutoring systems (ITS) have been developed in several domains to provide individualized guidance without a need for one teacher for each student, and have been shown to produce the same improvements as do the effective teaching methods. In order to be effective, intelligent tutoring systems require i) sufficient and high quality educational content, ii) detailed, domain specific content models to assess the difficulty levels of educational materials, iii) fine-grained, domain specific student models and additional equipment such as microphones, cameras, and sensors, and iv) an intelligent recommendation module that automatically provides students with interesting content of appropriate difficulty. However, it is very time-consuming and costly to prepare sufficient and high quality educational content as well as to build domain specific student and content models. They require intensive labor from the domain experts; therefore, have long been recognized as major bottlenecks for the development of ITS. Furthermore, additional equipment such as microphones and cameras that are used for modeling students behaviors outside the tutoring system are not available in most public schools. ^ This dissertation studies novel probabilistic approaches for effective and efficient user and content modeling for intelligent tutoring systems. In particular, we propose methods that i) analyze and model (i.e., detect the types of as well as identify the relevant and irrelevant information in) educational content without requiring domain experts' help, ii) model students' off-task behaviors with the equipment available in most schools, iii) model students' performance without a need for domain expert knowledge, and iv) jointly model students and educational content for more effective student and content modeling. A fully-functioning prototype system has been developed and evaluated in local schools. Empirical studies conducted on real-world datasets from the prototype system as well as on external large-scale datasets demonstrate the effectiveness of the proposed models.^

]]> Suleyman Cetintas Artificial Intelligence|Computer Science http://docs.lib.purdue.edu/dissertations/AAI3555230 http://docs.lib.purdue.edu/dissertations/AAI3555230 Wed, 22 May 2013 15:51:19 PDT The use of traditional techniques such as the shake table or the pseudo-dynamic (PSD) test are often used to validate and disseminate new technologies associated with structural response attenuation. At full-scale, the ability to perform such tests on realistic structures is limited. Real-time hybrid simulation (RTHS) offers an economical and reliable methodology for testing integrated structural systems with rate dependent behaviors. Within a RTHS implementation, critical components of the structural system under evaluation are physically tested, while the more predictable ones are replaced with computational models. Real-time execution, or performing the test with a one-to-one time scale, ensures that the tests yield more realistic responses. As a result, RTHS implementations provide an alternate approach to evaluating structural / rate-dependent systems under actual dynamic and inertial conditions without need for full-scale structural testing. ^ One significant challenge for successful RTHS is the availability of a robust and reliable simulation tool to accurately represent the physical complexities within the computational counterparts. Accurate computational models are required to ensure compatibility, stability and adequate synchronization between both computational and experimental substructures during testing. In this dissertation, the RT-Frame2D tool is proposed. The development, implementation and validation of this open source real-time computational platform intended for the hybrid simulation of dynamically-excited steel frame structures, is presented. ^ The computational platform is designed to recreate common sources of nonlinear behavior in steel frame structures, with adequate modeling and integration schemes to enable its flexible implementation within a typical RTHS platform. Through a series of numerical and experimental studies of typical RTHS scenarios, the capabilities of the tool are demonstrated, evaluated and validated.^

]]> Nestor E Castaneda Aguilar Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI3555228 http://docs.lib.purdue.edu/dissertations/AAI3555228 Wed, 22 May 2013 15:51:18 PDT The introduction of ambient ionization methods has increased the performance of analytical mass spectrometry. Ambient ionization permits the analysis of samples in their native environment with minimal to no sample preparation. The initial part of my dissertation research focused on studying the phenomena which governs the increase in reaction rates associated with bimolecular reactions in a variant of the conventional desorption electrospray ionization (DESI) method, reactive-DESI. Additionally, a methodology was developed to improve the spatial resolution (smallest feature distinguishable in a chemical image) of the technique, in another DESI experiment referred to as DESI imaging mass spectrometry, and enabled the resolution of features as small as 35 μm. High resolution imaging was demonstrated for both a conventional DESI source and a fixed geometry DESI source (FG)-DESI. My dissertation culminates with the use of low temperature plasma (LTP) ionization, a relatively new ambient ionization source for the imaging of semi-volatile fragrance compounds on various surfaces, determining high throughput capabilities and the distribution of compounds on a surface through chemical imaging. In summary, this dissertation has focused on studying the fundamental aspects and avenues for improving the applicability of various ambient ionization techniques.^

]]> Dahlia I Campbell Chemistry, Analytical http://docs.lib.purdue.edu/dissertations/AAI3555229 http://docs.lib.purdue.edu/dissertations/AAI3555229 Wed, 22 May 2013 15:51:18 PDT A significant challenge facing the cellulosic ethanol industry is the availability of robust industrial microbes that are capable of mixed sugar fermentation with tolerance to inhibitors. One such inhibitor is acetic acid, a compound released from the cellulosic biomass during pretreatment. Engineering an organism for improved inhibitor tolerance requires a fundamental understanding of the effect of acetic acid at a cellular level. ^ This dissertation evaluated the effect of acetic acid on the co-fermentation of glucose and xylose to ethanol using two approaches. (1) A kinetic model for the co-fermentation of glucose and xylose by S. cerevisiae 424A(LNH-ST) was developed to estimate important fermentation performance parameters. The resulting model showed acetic acid had a severe inhibitory impact on xylose fermentation. (2) The systems biology tools transcriptomics and metabolomics were used to determine the effect of acetic acid on gene expression levels and intracellular metabolite concentrations. Results showed that acetic acid does not have a singular inhibition mechanism, instead it was found to impact a variety of cellular processes.^

]]> Elizabeth Casey Biology, Systematic|Engineering, Agricultural http://docs.lib.purdue.edu/dissertations/AAI3555227 http://docs.lib.purdue.edu/dissertations/AAI3555227 Wed, 22 May 2013 15:51:17 PDT This study is an autobiographical investigation of my construction as a public school chess teacher from a blue-collar background. Exploring chess as both a form of cultural capital and a metaphor for social life (and especially the work of teaching), I trace my personal history from first learning the game to my present and intended future uses of it in classroom settings as part of the official curriculum. In the course of that exploration I also develop a narrative understanding of the working class circumstances into which I was born and the conflicted intellectual identity I forged through an upward class mobility that led me to become the first member of my immediate family to graduate from college. I further narrate my evolving understanding of chess as a possible school subject by reflecting on its status during my childhood schooldays and my working day as full-time chess teacher in a public school setting. ^ In the course of writing this study I have found that I am most at home—and am rewarded with the greatest sense of purpose—within the tensions and struggles of practical school life (why I feel like an amphibian too long out of water in more purely academic settings) and that I am a much more thoughtful teacher when I am actively writing about my work. It takes me a step beyond the old teacher/academic paradigm I used to think I had to straddle (straddling is a recurring theme I this work). This study finds me recognizing a personal and professional need to work within that tension and dialogue in both directions when possible—reclaiming the role of teacher as intellectual within the academic game and remaining closely tied to working class learning communities.^

]]> Jeffrey Dale Bulington Education, Curriculum and Instruction http://docs.lib.purdue.edu/dissertations/AAI3555226 http://docs.lib.purdue.edu/dissertations/AAI3555226 Wed, 22 May 2013 15:51:16 PDT An effective method to improve gas turbine propulsive efficiency is to increase the bypass ratio. With fan diameter reaching a practical limit, increases in bypass ratio can be obtained from reduced core engine size. Decreasing the engine core, results in small, high pressure compressor blading, and large relative tip clearances. At general rule of 1% reduction in compressor efficiency with a 1% increase in tip clearance, a 0.66% change in SFC indicates the entire engine is sensitive to high pressure compressor tip leakage flows. Therefore, further investigations and understanding of the rotor tip leakage flows can help to improve gas turbine engine efficiency. ^ The objectives of this research were to investigate tip leakage flows through computational modeling, examine the baseline experimental steady-stage performance, and acquire unsteady static pressure, over-the rotor to observe the tip leakage flow structure. While tip leakage flows have been investigated in the past, there have been no facilities capable of matching engine representative Reynolds number and Mach number while maintaining blade row interactions, presenting a unique and original flow field to investigate at the Purdue 3-stage axial compressor facility. ^ To aid the design of experimental hardware and determine the influence of clearance geometry on compressor performance, a computational model of the Purdue 3-stage compressor was investigated using a steady RANS CFD analysis. A cropped rotor and casing recess design was investigated to increase the rotor tip clearance. While there were small performance differences between the geometries, the tip leakage flow field was found independent of the design therefore designing future experimental hardware around a casing recess is valid. The largest clearance with flow margin past the design point was 4% tip clearance based on the computational model. ^ The Purdue 3-stage axial compressor facility was rebuilt and setup for high quality, detailed flow measurements during this investigation. A detailed investigation and sensitivity analysis of the inlet flow field found the influence by the inlet total temperature profile was important to performance calculations. This finding was significant and original as previous investigations have been conducted on low-speed machines where there is minimal temperature rise. ^ The steady state performance of the baseline 1.5% tip clearance case was outlined at design speed and three off-design speeds. The leakage flow from the rear seal, the inlet flow field and a thermal boundary condition over the casing was recorded at each operating point. Stage 1 was found to be the limiting stage independent of speed. Few datasets exist on multistage compressor performance with full boundary condition definitions, especially with off-design operating points presenting this as a unique dataset for CFD comparison. ^ The detailed unsteady pressure measurements were conducted over Rotor 1 at design and a near-stall operating condition to characterize the leakage trajectory and position. The leakage flow initial point closer to the leading edge and trajectory angle increased at the higher loading condition. The over-the-rotor static pressure field on Rotor 1 indicated similar trends between the computational model and the leakage trajectory.^

]]> John Richard Brossman Engineering, Aerospace|Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI3555224 http://docs.lib.purdue.edu/dissertations/AAI3555224 Wed, 22 May 2013 15:51:15 PDT The intent of this study was to determine how blindfolded participants perceive shape in a virtual environment and to determine if haptic cues can be used for spatial shape recognition and navigation through the use of geon based shapes. Participants were randomly assigned to three conditions: haptics/ sound, haptics, and sound. The participants ranged from 18-50 years of age with 88% being 18-30 years old. Fifty-three percent were female and 47% were male. Regardless of the type of cueing, 42% of participants selected the correct shape after a 7-9 minute interaction in a virtual environment while blindfolded. In addition, 91% of the participants did not have prior haptic experience. Some results did suggest that haptic and sound feedback may be necessary for active spatial perception of virtual shape to occur and might be a precursor to understanding more complex shape.^

]]> Nathan E Bench Psychology, Cognitive http://docs.lib.purdue.edu/dissertations/AAI3555225 http://docs.lib.purdue.edu/dissertations/AAI3555225 Wed, 22 May 2013 15:51:15 PDT As of 2012, unprecedented numbers of international undergraduate students are attending American universities, but in a period of globalization in which national borders and cultures are increasingly fluid, many of these students bring hybrid pre-college cultural and educational backgrounds. This study attempts to address one of these hybrid populations: Korean Early International Students. Korean Early International Students are Korean nationals who study outside of Korea at the primary or secondary level prior to entering American tertiary institutions. An attempt is made to begin to understand why students from a developed country such as Korea study overseas before college, what they hope to gain from an American education, the role played by the English language in their choices, and what experiences with composition they bring with them to an L2 composition classroom in the United States. ^ An attempt is made to explore the influence of different local circumstances and cultural contexts on decisions concerning education, and the author reviews his own experiences with the relationship between formal education and status, attitudes toward foreign languages and academic credentials, and composition while a student and instructor in the United States, Japan, and South Korea. The recent history of Korea and attitudes toward English are reviewed to provide a context for the decisions made by Korean Early International students. The study consists of a survey of L2 writers in sheltered composition sections at a large public university to ascertain their pre-college backgrounds and profiles of six Korean students registered for L2 composition. While no generalizable conclusions can be drawn from this pilot study, the six students profiled brought a broad range of international experiences with them to the university. Many of their choices regarding their educations seem to have been influenced by cultural and economic factors within Korea. It is suggested that a better understanding of the domestic contexts in which international students make the decision to study overseas will help Inner Circle institutions gain a greater appreciation for what motivates international students to seek an undergraduate education in the United States.^

]]> Harris Jon Bras Education, English as a Second Language http://docs.lib.purdue.edu/dissertations/AAI3555223 http://docs.lib.purdue.edu/dissertations/AAI3555223 Wed, 22 May 2013 15:51:14 PDT This dissertation explores approaches to inherent value in the natural environment. Contemporary theories of inherent moral value that ground environmental ethics are inadequate for at least one of two reasons: either they fail to offer a sufficient scope, or they fail to offer justification sufficient for application in policy and practice. I respond to a gap between the broad holistic but counterintuitive proposals of environmental ethics and the intuitive individualistic but narrow proposals of animal ethics with a novel relational theory of inherent moral worth based in semiotics, the study of signification. Native American, Judeo-Christian, and contemporary spiritual perspectives on inherent value like that of Holmes Rolston III are based on spiritual and transcendent cosmologies that are difficult if not impossible to justify. ^ Other approaches are grounded in moral intuitions developed out of growing scientific knowledge of the natural world, including those of Arne Naess, James Lovelock, and Aldo Leopold. Such approaches propose wide scopes of inherent value, proposing ways we might account for the moral worth of all things in the natural world, yet they too stand on unsteady foundations. ^ Similarly, approaches based on consciousness, social contract, rationality, and sentience face their own problems with justification. Approaches like these, strong in the contemporary literature concerning human and nonhuman moral value, have stronger justification, supported by scientific knowledge and our best understanding of the natural world, but ultimately find support in an abstract analogical extensionism. Further, they support narrower scopes of value that restrict their suitability as approaches to environmental value that are sufficient to describe the full range of moral value in the natural world. ^ Approaches that have strong scientific justification as well as broad scope remain in nascent stages of development. Adding to that development, I ultimately develop a novel approach to environmental value based in biosemiotics, the study of signification and representation in living systems. Biosemiotics presents an empirically-based theory of meaning-making by living things. This approach argues that meaning is morally-relevant, linking the science of biosemiotics to a descriptive ethical account. While significant problems remain with this approach, it reinvigorates the discussion of the scope and scientific justification of inherent worth in the natural world. ^ My dissertation evaluates ways of understanding the inherent moral worth of all living things, an essential step toward an environmental ethic. Furthermore, it enables us to better understand the implications of ecology, suggesting an essential albeit instrumental tie between the value of the living individual and the value of the nonliving world of which it is a part. The biosemiotic approach I explore here is a relational theory of ecological ethics, one piece of the wider picture of bioethics.^

]]> Jonathan Beever Environmental Philosophy|Ethics http://docs.lib.purdue.edu/dissertations/AAI3555222 http://docs.lib.purdue.edu/dissertations/AAI3555222 Wed, 22 May 2013 15:51:13 PDT Next-generation sequencing (NGS) technologies have opened the door to a wealth of knowledge and information about biological systems, particularly in genomics and epigenomics. These tools, although useful, carry with them additional technological and statistical challenges that need to be understood and addressed. Four separate, but related, NGS issues are addressed in this work. Specifically, we address amplification bias, an improvement in statistical power for differential methylation tests, boundary definitions and analyses for histone modifications, and the integration of genomic and epigenomic data in joint analyses. ^ The majority of NGS technologies effectively sample small amounts of DNA or RNA that are amplified (i.e., copied) prior to sequencing. The amplification process is not perfect, and thus sequenced read counts can be extremely biased. Unfortunately, current amplification bias controlling procedures introduce a dependence of gene expression on gene length. This issue is addressed via a novel procedure that accounts for amplification bias, and is effective in estimating true gene expression independent of gene length. ^ NGS technologies generate whole-genome epigenomic profiles at single base-pair resolution. Several novel statistical approaches are presented that incorporate genomic annotation information into the analysis of differential methylation and histone modification profiles for the purpose of increasing the statistical power. A novel application of hierarchical Bayesian modeling, that incorporates DNA methylation information into a differential gene expression testing framework, is also presented. The advantages of these approaches are demonstrated through extensive simulations and real data applications. ^

]]> Douglas D Baumann Statistics|Biology, Bioinformatics http://docs.lib.purdue.edu/dissertations/AAI3555220 http://docs.lib.purdue.edu/dissertations/AAI3555220 Wed, 22 May 2013 15:51:12 PDT The study of radical reactions has become a rapidly growing area of research because radicals initiate many chemical processes. These chemical processes include reactions in the atmosphere that cause depletion of the ozone layer, combustion reactions and certain biochemical processes, which proceed through radical intermediates. Radicals' reactivity towards biomolecules, such as proteins and DNA, has become of great interest since para-benzyne derivatives were discovered to be the biologically active intermediates of the potent enediyne anti-tumor antibiotics. Understanding the factors that govern the reactivity of these para-benzyne derivatives would be beneficial in helping to control their reactivity. Unfortunately, only limited experimental data have been reported on the parameters that play a role on the reactivity of para-benzyne derivatives. Their short lifetimes and high reactivities make studies in solution challenging. Fortunately, these challenges can be avoided by carrying out gas-phase experiments. Utilizing the distonic ion approach and tandem mass spectrometers, the gas-phase reactivities of several para-benzyne derivatives, as well as related σ-type monoradicals and biradicals, are reported in this thesis.^

]]> Enada F Archibold Chemistry, Organic|Chemistry, Physical http://docs.lib.purdue.edu/dissertations/AAI3555221 http://docs.lib.purdue.edu/dissertations/AAI3555221 Wed, 22 May 2013 15:51:12 PDT Understanding how geologists conduct fieldwork through analysis of problem solving has significant potential impact on field instruction methods. Recent progress has been made in this area but the problem solving behaviors displayed by geologists during fieldwork and the associated underlying cognition remains poorly understood. We present research showing how geology students initiate and develop geologic models as part of the problem solving process. We qualitatively analyzed field notes and interview data from 36 undergraduate geoscientists engaged in field exams while enrolled in a six-week advanced field camp. Eight cognitive frameworks grouped in two broad categories emerged from the data that show how students develop geologic models. Students employ both single and multiple model approaches with varying degrees of success and frequency. The success of any given approach is dependent on the level of students' geologic situational awareness. The development of multiple geologic models leads to a higher rate of success in general, because of the inherent flexibility to accommodate newly collected data. Instructors should continue to teach a multiple model approach until students have the proper geologic skills to ensure a high level of situational awareness and exhibit expert characteristics in the field. ^ In addition, we collected GPS navigation data from students during these field exams in order to understand the relationship between navigation, cognition, and performance. From the analysis of this data we found that over half of all stops are 1-4 minutes long, while very few of students' stops are longer than 9 minutes as the frequency of stops decreases as the duration increases. Regardless of performance or framework, there is an increase in shorter stops and decrease in longer stops from exam one to three, indicating that students changed the way they investigated as the field course progressed. Temporal signatures categorized by performance only show slight differences, but do indicate that there is an increase in very short and longer stops with declining performance. In contrast, higher performance is linked to an increase in short and medium length stops, suggesting that stops 4-14 minutes long are a "sweet spot" for investigation. We speculate that a high percentage of very short stops involve basic field tasks such as locating or data collection and that the decreasing frequency of long stops indicates that there is a relationship between the length of the stop and the complexity of the activities performed during that stop. Students increased experience leads to more efficient stops as they become more competent with field tasks and more versed in the regional geology. The GPS data we collected from these students while they took these notes allowing us to connect the duration of a stop to the types of notes produced during that stop. Note taking species occurred in various frequencies with the most common type being those that focused on lithologic, or lithologic & structural data collection. Stops that produced geologic models, specifically structural models, were much less frequent. The more frequent data collection stops are very short in length (typically 1-4 minutes), while the more complex stops tend to be longer in duration as the note taking gets more complex. Poor performing students had a high proportion of stops where they only collect lithologic data or stops where they don't generate any hypotheses. In contrast, successful students have more structural data and hypothesis generation in their notes. From this analysis we conclude that too much effort spent on stops with only basic data collection leaves less time for the cognitive effort required for model development, eventually leading to poor exam performance. Specifically, a higher frequency of lithologic data stops and lack of structural data leads to the development of incomplete geologic models or lack of comprehensive models altogether. Field instructors often educate their students on good note taking practices and critique the content of their students' field notebooks, and these findings can inform the content of that critique. Students' utilize many different problem solving approaches in the field, but we suggest that instructors continue to advocate a multiple model approach until students are capable of using a single model approach. In this approach students should decrease the number of geologic models they are using as the day progresses to avoid overwhelming themselves with data and hypothesis. Furthermore, field instructors need to work with students on developing their geologic investigation skills further and improving their efficiency. Specifically students need to collect a higher proportion of structural data and develop complete geologic models earlier in the day. (Abstract shortened by UMI.)^

]]> Russell N Balliet Geology|Education, Sciences http://docs.lib.purdue.edu/dissertations/AAI3555219 http://docs.lib.purdue.edu/dissertations/AAI3555219 Wed, 22 May 2013 15:51:11 PDT We apply the theory of Finite-size scaling (FSS) to an atomic and a non-equilibrium system in order to extract critical parameters. In atomic systems, we look at the energy dependence on the binding charge near threshold between bound and free states, where we seek the critical nuclear charge for stability. We use different ab initio methods, such as Hartree-Fock, Density Functional Theory, and exact formulations implemented numerically with the finite-element method (FEM). Using Finite-size scaling formalism, where in this case the size of the system is related to the number of elements used in the basis expansion of the wavefunction, we predict critical parameters in the large basis limit. Results prove to be in good agreement with previous Slater-basis set calculations and demonstrate that this combined approach provides a promising first-principles approach to describe quantum phase transitions for materials and extended systems. ^ In the second part we look at non-equilibrium one-dimensional model known as the raise and peel model describing a growing surface which grows locally and has non-local desorption. For a specific values of adsorption ( u_a) and desorption (u_d) the model shows interesting features. At u_a = u_d, the model is described by a conformal field theory (with conformal charge c = 0) and its stationary probability can be mapped to the ground state of a quantum chain and can also be related a two dimensional statistical model. For u_a ≥ u_d, the model shows a scale invariant phase in the avalanche distribution. In this work we study the surface dynamics by looking at avalanche distributions using FSS formalism and explore the effect of changing the boundary conditions of the model. The model shows the same universality for the cases with and with our the wall for an odd number of tiles removed, but we find a new exponent in the presence of a wall for an even number of avalanches released. We provide new conjecture for the probability distribution of avalanches with a wall obtained by using exact diagonalization of small lattices and Monte-Carlo simulations.^

]]> Edwin A Antillon Physics, Atomic|Physics, Theory http://docs.lib.purdue.edu/dissertations/AAI3555217 http://docs.lib.purdue.edu/dissertations/AAI3555217 Wed, 22 May 2013 15:51:10 PDT In this dissertation, I argue that the spatial figure of nature that we have inherited from Descartes should be reformulated in terms of time in order to arrive at a philosophically adequate concept of nature.^

]]> Marco Altamirano Metaphysics|Philosophy http://docs.lib.purdue.edu/dissertations/AAI3555218 http://docs.lib.purdue.edu/dissertations/AAI3555218 Wed, 22 May 2013 15:51:10 PDT We live in a suburban society. In my thesis, I argue that suburbanism reflects a state of alienation that John Dewey became concerned with in the first half of the 20^th Century, and persists to this day. My work begins by investigating the relationship John Dewey established between habits and the environment in his work on ethics. I draw attention to Dewey's claim that habits - that is to say the various ways we actually conduct ourselves - are the best representation of our notions of right and wrong and what we value. I also explicate the role Dewey ascribed to the environment in either abetting or hindering the development of new habits, and hence new modes of ethical conduct. What I demonstrate is that for Dewey, changing our moral conduct (again, best understood as habits) is far more difficult than most philosophers recognize because in order to change habits, it is also necessary to physically change the environment in which those habits occur. But my investigation revealed two important themes in Dewey's work that had largely gone unnoticed. ^ First, in establishing a strong link between habits and the environment, Dewey was in fact articulating a theory of alienation. Specifically, it became clear to me that Dewey believed that when our habits were rooted in an environment (best understood as both the natural environment and what has come to be termed the `built environment') that no longer existed, we were alienated. This notion of alienation reflects Dewey's commitment to a naturalistic approach to philosophical concepts. In particular, Dewey's theory of alienation can be likened to Darwinian concepts, most notably the role adaptation plays in evolution. I concluded that Dewey recognized that because we continuously transform our environment, thereby rendering various habits obsolete, we periodically become alienated. ^ My conclusion that Dewey recognized that we periodically alienate ourselves by rendering old modes of conduct ill-suited to the environment, revealed a second feature of Dewey's work that had been under researched. Namely, when we are alienated, human agency is called into question. Through a detailed analysis of several of Dewey's works (Human Nature and Conduct, Individualism Old and New, and Art as Experience) I showed that Dewey was deeply concerned with the possibility that when old habits persisted, even when radical transformations had taken place in the environment, that directing the way the environment changes becomes difficult, and human agency becomes limited. My work indicated that Dewey thought that for agency to be possible, it had to be rooted - and therefore reactive to - lived experience. But when old habits, rather than actual experience determine how we react to the world around us, experience and hence agency become impossible. In my work I showed that Dewey felt that the Industrial Revolution had indeed created a deep schism between old habits and the way the environment actually existed, and thus he was deeply worried that we were losing our ability to shape the world and human agency was indeed being lost. ^ I conclude my dissertation by investigating whether the conditions Dewey identified have changed, either for better or for worse. My work suggests that the conditions of alienation, and hence loss of human agency have in fact worsened since Dewey first raised his concerns. I argue that rather than changing the environment to create conditions in which new habits could emerge, we have changed the environment in an effort to accommodate old habits. The primary change we have made is that we have become a sprawling suburban society, rather than a densely populated urban society. This was done to satisfy old habits rooted in notions of rugged individualism. But these changes have been superficial, because they deny the collaborative and collective nature of post- Industrial Revolution life. And so alienation and lack of agency not only persist, they have become more pronounced. A corollary to my claim is that the changes we have made in order to satisfy old habits (again, modes of conduct) have damaged both the built-environment and the natural environment. I conclude by arguing that only a return to urban living can create an environment in which new habits can emerge.^

]]> Alexander W Anderson American Studies|Environmental Philosophy|Philosophy http://docs.lib.purdue.edu/dissertations/AAI3555216 http://docs.lib.purdue.edu/dissertations/AAI3555216 Wed, 22 May 2013 15:51:09 PDT Detection and identification of special nuclear materials can be fully performed with a radiation detector-spectrometer. Due to several physical and computational limitations, development of fast and accurate radioisotope identifier (RIID) algorithms is essential for automated radioactive source detection and characterization. The challenge is to identify individual isotope signatures embedded in spectral signature aggregation. In addition, background and isotope spectra overlap to further complicate the signal analysis. These concerns are addressed, in this thesis, through a set of intelligent methodologies recognizing signature spectra, background spectrum and, subsequently, identifying radionuclides. Initially, a method for detection and extraction of signature patterns is accomplished by means of fuzzy logic. The fuzzy logic methodology is applied on three types of radiation signal processing applications, where it exhibits high positive detection, low false alarm rate and very short execution time, while outperforming the maximum likelihood fitting approach. In addition, an innovative Pareto optimal multiobjective fitting of gamma ray spectra using evolutionary computing is presented. The methodology exhibits perfect identification while performs better than single objective fitting. Lastly, an innovative kernel based machine learning methodology was developed for estimating natural background spectrum in gamma ray spectra. The novelty of the methodology lies in the fact that it implements a data based approach and does not require any explicit physics modeling. Results show that kernel based method adequately estimates the gamma background, but algorithm's performance exhibits a strong dependence on the selected kernel.^

]]> Miltiadis Alamaniotis Engineering, Nuclear|Artificial Intelligence|Computer Science http://docs.lib.purdue.edu/dissertations/AAI3555215 http://docs.lib.purdue.edu/dissertations/AAI3555215 Wed, 22 May 2013 15:51:08 PDT Effective planning and management of water resources at the watershed scale using strategies such as low impact development (LID), requires an understanding of variations in runoff and baseflow processes. The scientific literature, however, provides limited quantitative information describing potential impacts of LID practices at the watershed scale. Further, little information is available for exploring the impacts of LID practice adoption on baseflow processes. Computational methods for baseflow estimation for modeling LID practices at the watershed scale were developed and evaluated with data from Indiana watersheds. The method consists of techniques to develop baseflow equations, determine baseflow threshold area, and estimate baseflow pollutant coefficients for individual land use types. Estimated baseflow in the study watersheds indicated that baseflow represents an important proportion (approximately 60%) of total streamflow, suggesting that a better understanding of variations in baseflow quantity and quality can help improve watershed planning and management strategies. Differentiation of baseflow pollutant coefficients for individual land uses revealed that the proposed method is a viable option to isolate constituent mean concentrations for land use types in a watershed. ^ To evaluate potential impacts of LID adoption on runoff, baseflow, total flow, and pollutant loading, a framework was developed to represent, evaluate, and report the effectiveness of LID practices using the Long-Term Hydrologic Impact Assessment-Low Impact Development (L-THIA-LID) model. The LID practices were represented with modified curve number (CN) values in the L-THIA-LID model. The proposed methods (i.e., baseflow estimation and LID representation) were utilized to enhance the capabilities of the L-THIA-LID model, which was applied in two urbanized watersheds to show that various levels of LID adoption can be used as retrofitting technologies to reduce hydrology and water quality impacts of urban development. ^ Finally, a numerical procedure to quantify uncertainty associated with the L-THIA-LID model output was developed. Most of total variance in runoff and baseflow estimates originated respectively from uncertainty in precipitation data and watershed drainage area. Uncertainty in total streamflow was largely due to uncertainty in baseflow estimates. Minimization of uncertainty sources of the L-THIA-LID model would likely result in more accurate model predictions as an easy-to-use decision support tool.^

]]> Laurent Mensah Ahiablame Water Resource Management|Engineering, Environmental|Urban and Regional Planning http://docs.lib.purdue.edu/dissertations/AAI3555214 http://docs.lib.purdue.edu/dissertations/AAI3555214 Wed, 22 May 2013 15:51:07 PDT With the explosion of data, all communication systems need to provide increased data rates and higher reliability. This work investigates the advantages of using channel output feedback in communication systems to achieve these goals. We begin by looking at the role channel output feedback can play for additive Gaussian noise channels. In particular, we consider two scenarios, one with a point-point link and the other with a helper relay node. For a point-point link, we propose an optimal coding strategy that takes feedback noise into account. For a three terminal relay, we propose a new lower bound on the achievable rate in the case of ideal channel output feedback. We also propose a coding strategy for the noisy channel output feedback case. ^ Subsequently, we explore the improvements in reliability for fading systems using channel output feedback. Most of the previous work for fading channels with feedback has been limited to the exploitation of channel state information (CSI) at the source. In this work, the design of a coding scheme for multiple-input multiple-output (MIMO) fading systems with channel output and channel state feedback is considered. ^ We propose a simple linear coding strategy that achieves any rate up to the capacity of the channel. This linear processing scheme can provide a doubly exponential probability of error decay with the size of blocklength for any rate less than capacity. This scheme is extended to non-ideal feedback involving the following two scenarios: quantized CSI sent from the destination to the source and noisy channel output feedback from the destination to the source. ^ Finally, we investigate practical performance benefits from our proposed scheme by incorporating it in the hybrid automatic repeat request (ARQ) protocol. Using simulations, we demonstrate that substantial improvements in the overall throughput of hybrid ARQ systems can be obtained by the adoption of our proposed scheme.^

]]> Mayur Agrawal Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI3554050 http://docs.lib.purdue.edu/dissertations/AAI3554050 Wed, 22 May 2013 15:51:07 PDT This dissertation examines linguistic spatial frame of reference (FoR) usage across three cohorts, detailing the lexical and structural realization of particular spatial FoR classes within each linguistic community, as well as which linguistic and nonlinguistic factors are predictors of spatial FoR class usage.^ This study was designed to determine the degree to which language and environment are predictive factors of spatial FoR performance. Sumu-Mayangna (Misumalpan; Nicaragua) and Nicaraguan Spanish were chosen because while their speakers share a local environment, the languages are genetically unrelated. On the other hand, Nicaraguan Spanish and Barcelona Spanish were chosen because, apart from speakers' access to similar linguistic resources, speakers of these two varieties occupy rather different environments. Over thirty-two hours of discourse data from three referential communication tasks were analyzed using generalized logit mixed models. Descriptive and predictive statistical analyses indicate that a constellation of factors are significant in terms of the production of linguistic spatial FoR preference across cohorts and tasks. Cohort, language, and environment were found to be predictive factors, with language identified as the most common predictor of spatial FoR usage. In contrast, age and gender were found to be marginally predictive.^ A subsequent qualitative analysis elaborates upon the quantitative results, showing that between speakers of the two Spanish varieties, there is evidence of an asymmetry in form-to-concept mapping with regard to spatial relators. In the same vein, spatial relators in Sumu-Mayangna are discussed in the context of meronymy. The relative productivity and geometric organization of the Sumu-Mayangna meronymy system is discussed. Additionally, evidence found to be supportive of Bohnemeyer's meronymy hypothesis is presented, which provides some explanation as to the non-preference of relative spatial FoR classes in the Sumu-Mayangna case. This study concludes that a combination of factors may ultimately predict spatial FoR usage, with language, and specifically, its attendant community-specific discourse practices, playing a unique role.^

]]> Alyson G Eggleston Language, Linguistics|Sociology, Sociolinguistics http://docs.lib.purdue.edu/dissertations/AAI3546357 http://docs.lib.purdue.edu/dissertations/AAI3546357 Wed, 22 May 2013 15:51:06 PDT A city-wide wireless sewer sensor system becomes "intelligent" by having adaptive manhole cover antennas and spectrally aware tunable filters which adapt to an urban radio environment. 150 wireless sensor nodes have been developed and deployed to monitor the sewer flow and to reduce the frequency of the sewer overflow during heavy storm runoff in the mid-sized city: South Bend, Indiana in the US. The challenge for the wireless designer is to design a radiator which operates below ground as well as to improve the communication performance of the wireless sensor system. In addition, the wireless sensor network was often limited by out-of-band strong interference. Therefore, adaptability to the electrical environment is the key factor for wireless communication. ^ In the first approach, a conventional cast-iron manhole cover was replaced with a composite manhole cover to create a radiator which is not only mechanically strong but also electrically functional. The utilization of parasitic antennas is explored to demonstrate the effect of limited beam scanning on a real sensor network system. The combination of an electronically steerable beamforming capability and an angular diversity technique in this antenna allowed the antenna to adapt to its radio environment and find an optimal receive characteristics. The sensor measurement result indicates that the intelligence of the antenna significantly improves packet reception rate and RSSI (Received Signal Strength Indication). In the second approach, the effect of an adaptive front end is investigated to mitigate these nearby interferers. The sensor motes operated at a fixed band, the unlicensed band of 900MHz, and did not have the frequency adaptability of future cognitive radios. Yet, the effect was demonstrative of the potential benefits of adaptive preselect filtering. The measured result shows substantial improvements over the fixed band system by even slight tuning of the bandwidth and/or the center frequency of the preselect filter. Experimentally and numerically we show that both tuning in the filter bandwidth and/or center frequency can significantly improve the packet reception rate. A guideline for an optimized filtering technique is given to provide broad understanding of how the adaptable preselect filtering can be utilized. The optimal filtering point can be found based on frequency spectrum and filter attenuation response. ^

]]> Seong Heon Jeong Engineering, Electronics and Electrical|Physics, Electricity and Magnetism http://docs.lib.purdue.edu/dissertations/AAI3545314 http://docs.lib.purdue.edu/dissertations/AAI3545314 Wed, 22 May 2013 15:51:01 PDT The purpose of the study was to examine how two Taiwanese and two Chinese families adapted to American schooling and parenting while recognizing and honoring their native cultural background. More specifically, the study explores the families' cultural adaptations as defined by differences in language and literacy experiences that go beyond a simple language barrier. ^ In the four case studies, the key participants include four parents and their preschoolers. Data came from interviews and observations. Following data analysis, three findings highlight perspectives from four families. First, the study indicates that Taiwanese and Chinese families' American schooling experiences differ greatly from their home country. Second, the study reflects a more substantive understanding of their adaptation to their community practices and multiple strategies that these families appropriate in their interpretation of adaptation. Third, this study addresses the conflict between cultures that are present in cultural adaptations and literacy learning. The study sheds light on the adaptation of Taiwanese and Chinese families to schooling in the United States. It indicates that further studies of Chinese families need to be aware of their stance, embedded in Chinese culture and beliefs, in order to understand how cultural practices mediate their responses to schooling, parenting, and literacy learning. This study leaves us with significant implications for future research as well as for educational practices, especially at the university level.^

]]> Wei-Chun Liu Education, Multilingual http://docs.lib.purdue.edu/dissertations/AAI3544389 http://docs.lib.purdue.edu/dissertations/AAI3544389 Wed, 22 May 2013 15:50:55 PDT Peer-to-Peer (P2P) streaming technologies can take advantage of the upload capacity of clients, and hence can scale to large content distribution networks with lower cost. It is highly desirable that most of the control decisions be decentralized, with each peer only interacting with a small number of other peers/neighbors. However, this requirement has made the analytical study of the performance of P2P systems particularly challenging. In this thesis, we rigorously study the achievable streaming capacity of large-scale P2P streaming systems, either live streaming or video-on-demand, with sparse connectivity among peers, and investigate simple and decentralized P2P control strategies that can provably achieve close-to-optimal streaming capacity. We show that even with a random peer-selection algorithm and uniform rate allocation, as long as each peer maintains Θ (log N) downstream neighbors, where N is the total number of peers in the system, the system can asymptotically achieve a streaming rate that is close to the optimal streaming rate of a complete network. Further, the tracker does not need to obtain detailed knowledge of which chunks each peer caches, and hence incurs low overhead. We then study multiple streaming channels where peers watching one channel may help in another channel with insufficient upload bandwidth. We propose a simple random cache-placement strategy, and show that a close-to-optimal streaming capacity region for all channels can be attained with high probability, again with only Θ (log N) per-peer neighbors. A distinct advantage of the cache placement strategy is its robustness to imprecise estimates of system parameters such as video popularity and upload bandwidth distribution. Simulation results are provided to verify our analysis.^

]]> Can Zhao Engineering, Electronics and Electrical|Technical Communication http://docs.lib.purdue.edu/dissertations/AAI3544386 http://docs.lib.purdue.edu/dissertations/AAI3544386 Wed, 22 May 2013 15:50:54 PDT A Landau-Ginzburg-Devonshire phenomenological theory was developed and numerically implemented by explicitly defining the underlying coefficients as a function of observable experimental hysteresis loop data. For polycrystalline materials, spatially resolved numerical simulations identify and quantify the appearance of three polarization populations, namely, simple switching, negatively switching and pinned domains, to describe the microscopic switching of ferroelectric domains. The electric load ratio, i.e., R_E = E_min/E _max, is defined to describe different sesquipolar cycling conditions. In comparison to the R_E = -1 (bipolar) regime, tensile stresses are minimized in the -1 < R_E < 0 (sesquipolar) regime by 33% and compressive stress minimized by 38%, while the maximum strain output decreases by only 1%. Additionally, calculations predict that a first-order transition from ferroelectric to relaxor develops at σ_c = 15 MPa. Results further demonstrate that a metastable state develops at zero polarization when the sample is subject to external compressive stress, which is a result of a local free energy minimum. The frequency dependent hysteresis response shows that a transition between relaxor ferroelectric and antiferroelectric develops at a critical cycling frequency, in agreement with previous publications. Numerical simulations predict that the built-in electric field increases quadratically as a function of applied compressive stress fields, in agreement with experiments. Such a trend is a result of thermal expansion and piezoelectric contributions for small compressive stresses, and a result of electrostrictive contributions and stress-induced phase transformations for large stresses. Finally, the effect of temperature on the electrical and electromechanical response demonstrates a phase transition occurs at T_d = 294 K for BNT-BT lead free system. Frequency dependent hysteresis behavior show that a maximum strain output is obtained at T ≈ 320 K in a finite frequency range of 0.1Hz to 1Hz. A composition-temperature phase diagram that extends the published work is proposed, in which the morphotropic phase boundary extends to included x = 0.07 composition and the KNN modification suppresses the transition temperature from relaxor to antiferroelectric regime, in agreement with published work. The calculated composition-temperature hysteresis behavior demonstrates a strong frequency dependence, which can be tuned to meet electromechanical device specifications.^

]]> Zizhao Zhao Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI3544379 http://docs.lib.purdue.edu/dissertations/AAI3544379 Wed, 22 May 2013 15:50:53 PDT This dissertation examines the social identity of adjunct faculty and the implications for writing program administrators (WPAs). With the ever increasing reliance on Master's degree teachers to teach first-year composition and other writing classes, WPAs are faced with the task of attempting to bring some level of disciplinary coherence to writing programs. This study consists of interviews of adjuncts at a Midwestern University that employed up to 50 adjuncts a year. Interview questions were developed using social identity theory. Interview results were analyzed via expertise and career theories. Findings indicate that adjuncts who do not have a Rhetoric and Composition PhD are unlikely to have a social identity as a member of the discipline and are unlikely to achieve expert status as disciplinary teachers. Recommendations are presented for strengthening writing programs and in addressing the national adjunct situation.^

]]> Mark Edward Sidey Education, Language and Literature|Psychology, Social|Education, Teacher Training|Language, Rhetoric and Composition|Education, Higher http://docs.lib.purdue.edu/dissertations/AAI3544378 http://docs.lib.purdue.edu/dissertations/AAI3544378 Wed, 22 May 2013 15:50:53 PDT The purpose of this study was to investigate the use of the picture plus discussion (PPD) intervention on the comprehension abilities of high school students with moderate intellectual disability when read a variety of expository texts aloud. A multiple probe single subject design was employed to measure the effect of the intervention across three different texts including leveled SRA readers, stories from a local newspaper, and sections from employee handbooks. Results indicate that the PPD intervention was successful in increasing comprehension as measured by the students' story retell abilities. Comprehension assessment was collected in both three option knowledge based multiple-choice questions and student retell of the text content. While mixed results were observed in the multiple-choice accuracy, this study revealed that the PPD intervention was effective in increasing student comprehension by improving the story retell in terms of quantity (i.e. word count and idea units) and quality (i.e. text and picture relevant idea units) across the text types. These overall positive effects were replicated in the generalization phase, which involved peer supports in an inclusive, neutral school setting.^

]]> Jordan C Shurr Education, Special|Education, Secondary|Education, Reading http://docs.lib.purdue.edu/dissertations/AAI3544377 http://docs.lib.purdue.edu/dissertations/AAI3544377 Wed, 22 May 2013 15:50:52 PDT Winter wheat (Triticum aestivum L.) yield in Indiana is highly dependent upon environmental factors in the growing season and the management imposed by the producer. The objectives of the first study, located in Evansville and West Lafayette, Indiana in 2009 and 2010 were to determine the effects of seeding rate, nitrogen fertilizer, seed treatment-insecticide, foliar insecticide and foliar fungicide treatments on responses of seven varieties of soft red winter wheat. Wheat varieties did not vary in their responses to management inputs in either year or location. A second topdress application of nitrogen fertilizer (increasing N rate from 140 to 190 kg N ha^-1 at Evansville and from 132 to 176 kg N ha^-1 at West Lafayette) led to an increase in yield in challenging years, though this effect was reduced in highly productive environments. The yield increase was not associated with a decrease in grain quality measured by protein content, milling and baking qualities. In addition, economic analysis of the production systems showed that in high producing years and locations, investing in additional nitrogen decreased profit. In challenging environments, the higher investment in both seed and nitrogen resulted in higher annual net returns on both a per land area and per unit of grain yield basis. ^ In the second study, the primary objective was to determine whether winter wheat based cropping systems in the Midwest have the potential to produce grain, forage or biofuel feedstock that is profitable. Fifteen winter wheat based double cropping systems and five single crop systems were studied near West Lafayette, Indiana in the 2009 and 2010 growing seasons to measure the impacts of no-till planting into wheat stubble and delayed planting on grain and dry matter yield, forage quality and potential energy yield. Winter wheat was harvested at boot, heading and at grain maturity stages as either whole plant silage or grain plus straw. The second crops tested were corn for grain, whole-plant silage corn, grain sorghum, sweet sorghum, silage sorghum and soybean. Each of these double-crop species were seeded on at least two planting dates as soon as possible after wheat harvest. Budgets were developed to gauge the profitability of the systems, and liquid fuel potential and total energy content of each system were assessed using conversion values from recent literature. This study found significant dry matter (DM) yield losses associated with planting grain corn, silage corn, and silage sorghum (but not soybean) into wheat stubble compared to bare ground. Differences in protein and fiber content, and digestibility were a function of double-crop species and planting dates. Enterprise budgets revealed that single crop systems or double cropping wheat with soybean were most profitable at the first planting date. At the second planting date, the ensiled winter wheat and soybean double-crop system was profitable in both years, while the silage sorghum and sweet sorghum double crop systems were profitable in one of the two years. At the third planting date, all five systems generated losses in 2009, but the soybean and silage sorghum double-crop systems generated a profit in 2010. All cropping systems were assessed for total energy yield, measured by total heat of combustion (GJ ha^-1). The maximum energy yielding systems at each planting date were wheat greenchop plus silage sorghum, wheat silage plus silage corn, and winter wheat grain/straw plus silage sorghum for the three wheat harvests, respectively. Total heat of combustion (GJ ha^-1) trends followed with those observed for liquid fuel in the form of fermentation or cellulosic ethanol conversion. Selected alternative cropping systems based on winter wheat were highly productive in terms of tonnage, economic and energy yields, but the overall system productivity was very dependent on the crop management plus harvest options adopted in both wheat and any crops that followed.^

]]> Samantha Suellen Shoaf Agriculture, Agronomy http://docs.lib.purdue.edu/dissertations/AAI3544375 http://docs.lib.purdue.edu/dissertations/AAI3544375 Wed, 22 May 2013 15:50:51 PDT Ad hoc wireless networks are vulnerable to a wide range of security attacks, due to the ease of the nodes being compromised and the cooperative nature of these networks. A solution approach widely used for defending these networks is behavior-based detection. In this, nodes overhear communications in their neighborhood exploiting the open nature of the wireless medium, and determine if the behaviors of their neighbors are legitimate. An important issue with behavior-based detection that arises in multi-channel ad hoc wireless networks is on which channels monitoring nodes should overhear their neighbors' communications. ^ In this dissertation, we develop a framework for behavior-based detection in multi-channel ad hoc wireless networks. We are interested in the issue of how to optimally place monitoring nodes and to select channels to tune their radios to. We show that the problem is NP-hard, then develop approximation algorithms. We show that one of our algorithms attains the best approximation ratio achievable among all polynomial-time algorithms. Also, we develop distributed channel assignment algorithms for large-scale and dynamic networks. The distributed nature of the algorithm allows it to scale to large networks. Further, we allow for imperfect detection, where monitoring nodes may probabilistically fail to detect malicious behaviors. For this scenario, we consider providing multiple covers to each node, thereby still maintaining the detection accuracy above a certain level. We evaluate our algorithms for random and scale-free networks and consider optimizations for practical deployment scenarios, such as when the network configuration is changing fast versus a relatively static network.^

]]> Donghoon Shin Engineering, Computer|Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI3544372 http://docs.lib.purdue.edu/dissertations/AAI3544372 Wed, 22 May 2013 15:50:50 PDT For many adults, including older adults, a marital partner is their central social relationship and this important tie can have health implications particularly within the chronic illness context. In addition, chronic illness care has shifted from long and frequent hospital stays to outpatient care for managing illness over an extended period of time. As the interactions within a marriage are posited to influence a patient's chronic illness management (see reviews Kiecolt-Glaser & Newton, 2001; Robles & Kiecolt-Glaser, 2003), the primary aim of this study is to determine the association between spouse involvement and patient chronic illness management and marital satisfaction. A second aim of this study is to explore the relational context as a potential moderator of the association of spouse involvement with chronic illness management and marital satisfaction. Findings suggest that supporting patients' healthy dietary habits may be particularly beneficial at reinforcing patients' current efforts to manage their diet. Whereas, pressuring patients to change their behavior may be met with unintended interference with adherence. Additionally, the different findings between spouse diet-related persuasion and pressure suggest that spouse control has multiple facets warranting further research to examine their effectiveness within an illness context. This study contributed to the examination of potential moderators between spouse involvement and patient outcomes suggesting that one size does not fit all. For couples where the spouse reports eating a healthful diet more often, patients may feel discouraged by their spouses' attempts to change their diet habits when spouses may not seem to be struggling in maintaining a healthy diet resulting in poorer patient dietary adherence.^

]]> Amber J Seidel Gerontology|Health Sciences, Aging|Sociology, Individual and Family Studies http://docs.lib.purdue.edu/dissertations/AAI3544373 http://docs.lib.purdue.edu/dissertations/AAI3544373 Wed, 22 May 2013 15:50:50 PDT Petrochemical asphalt binder modifiers are used to enhance performance properties of flexible pavements. National transportation agencies have expressed interest in asphalt binder modifiers from renewable resources. Acidulated soybean soapstock with its surfactant qualities and soybean vulcanized vegetable oil (VVO) with its elastic properties are two possible soybean oil-based modifiers that may improve asphalt binder performance. Research with vegetable oil-based asphalt binder modifiers has shown chemical changes which affect high and low temperature properties in addition to moisture susceptibility. The purpose of this examination is first to demonstrate the high and low rheological properties and moisture susceptibility of these asphalt binder soybean oil-based modifier blends. Since modifying asphalt binder will alter its chemical functionality, the second aim of this study is to verify the chemical mechanism(s) of asphalt binder modification. ^ High temperature testing demonstrates that soybean VVO produces harmful sulfur emissions at high temperatures and does not behave as an elastomer in asphalt binder contrary to expectations. Additional high temperature testing indicates that asphalt binders modified with acidulated soybean soapstock show a reduction in softening point, viscosity and complex modulus, as well as an increase in phase angle. However, low temperature results of binder modification are source specific with no clear trend in stiffness or flexural creep flow rate. Asphalt binders modified with 1 percent acidulated soybean soapstock generally perform better than unmodified asphalt binders or asphalt binders with a 3 percent modification level. Results from moisture susceptibility testing suggest that asphalt binders modified with 1 percent acidulated soybean soapstock perform as well or better than unmodified asphalt binders. ^ Regarding chemical functionality, evidence suggests that the soy fatty acids in acidulated soybean soapstock may have two functions. One function is to act as a low molecular weight solvent and the second is to act as molecular lubrication. Additionally, results suggest that moisture resistant divalent bonding may be facilitated by the adding 1 percent acidulated soybean soapstock. ^ It is the recommendation of this investigation that binders modified with 1 percent acidulated soybean soapstock be considered for engineering applications using polymer modified binders and 3 percent acidulated soybean soapstock for recycled asphalt pavements.^

]]> Joseph Cameron Seidel Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI3544369 http://docs.lib.purdue.edu/dissertations/AAI3544369 Wed, 22 May 2013 15:50:49 PDT Rhetoric of the Thirstland: Discourse and Democracy in Botswana, is a study of the historical and contemporary rhetorical practices of the Tswana, the majority ethnic/cultural group in the nation-state of Botswana. The project is situated within the rhetoric and composition subfield often called comparative or cultural rhetorics, which seek to widen the field of rhetorical studies beyond the West, thus allowing a richer and deeper understanding of discourse to develop But comparative rhetoric studies of sub-Saharan Africa remain scarce. Rhetoric of the Thirstland: Discourse and Democracy in Botswana is one attempt to fill that gap. As the oldest multi-party democracy and one of Africa's most politically stable countries, Botswana is a particularly interesting rhetorical context for study. In my dissertation, I argue that the indigenous political and rhetorical practices of the Tswana fostered a sense of communal identity and allowed for the negotiation of conflict and difference. Moreover, I demonstrate how these practices have carried forward into post-colonial Botswana to create distinctive conditions that help sustain peace and stability in Botswana today. Finally, I draw some comparisons between traditional Tswana rhetoric and dominant Africalogical and Western theories of discourse.^

]]> Megan Schoen Sociology, Ethnic and Racial Studies|Sub Saharan Africa Studies|Language, Rhetoric and Composition http://docs.lib.purdue.edu/dissertations/AAI3544364 http://docs.lib.purdue.edu/dissertations/AAI3544364 Wed, 22 May 2013 15:50:47 PDT In the first chapter, we explore the effect of regulation on firms under monopolistic competition. New environmental regulations often impose stricter efficiency standards on manufacturers. The regulations impose specific cutoff dates by which manufacturers should cease production of the older version of the product and (potentially) offer new redesigned products with higher efficiencies. However, while the manufacture of the old product is banned, US regulations typically allow the continued sale of inventory in the supply chain after the cutoff date. We take the perspective of a single company, whose design choice only marginally impacts other firms in the industry (monopolistic competition). Our goal is twofold i.e., to identify the optimal design choice for the new product, and the associated inventory build up of the old product in advance of the cutoff date. We thus combine logistics considerations with new product design decisions to optimize profits. We explore the effects of product, customer and industry characteristics on the manufacturers' choices, and find that they can have significant impacts on the design decision for the new product and the inventory levels of the old product. ^ In the second chapter, we estimate the impact of environmental regulations in the US appliance industry on operational decisions and shareholder wealth. The US regulatory approach for implementing minimum energy efficiency standards is to ban the production and import but not the sale of non-conformant appliances beyond the effective date, provided that sales are from pre-existing inventory. We find significant inventory stockpiling before the effective date, with an average annual inventory growth of 15.18%. Second, we observe significant abnormal returns of -2.48% around the announcement date, and of -2.09% around the effective date, implying that significant pieces of information, related to the operational implementation of the transition, are revealed only around the effective date. Finally, we find that top performing firms have different operational strategies than low performers, resulting on average in 9.64% higher abnormal returns. This suggests that carefully managing the operational implementation of product transitions can result in important financial benefits. ^ Finally, in chapter three, we extend the study in chapter one to the case of competition. We model how competition influences a manufacturer's new product design choice under a deterministic and then a probabilistic demand model. In the first model, we propose how the characteristics of manufacturers effect the equilibrium solution i.e., design choice. Then, for the second model, we try to compare duopolist's equilibrium design to monopolist's optimal design given different customer choice models.^

]]> Mohammad E. A Saoud Business Administration, Management|Economics, General|Operations Research http://docs.lib.purdue.edu/dissertations/AAI3544361 http://docs.lib.purdue.edu/dissertations/AAI3544361 Wed, 22 May 2013 15:50:47 PDT This study investigated determinants of diet-related support using Dunkel-Schetter and Skokan's (1990) multifactorial model. For patients with type 2 diabetes and their spouses (N = 56 couples), each partner's attachment anxiety and attachment avoidance was conceptualized as provider and recipient factors, marital satisfaction was examined as relationship factor, diet adherence and HbA1c were explored as stress factors. Spouses' own attachment anxiety and attachment avoidance, as well as patients' diet adherence were found to be predictors of spouses' diet-related support provision. In addition, findings revealed that patients with type 2 diabetes promote healthy eating habits of their spouses through diet-related support. Patients' marital satisfaction and spouses' following a healthy eating plan were associated with patients' provision of diet-related support to their spouses. Findings of this study support the perspective that provision of support is multiply determined and extend beyond characteristics of the provider to include the broader relational context of patients and their spouses.^

]]> Zubeyde Seda Sahin Psychology, Behavioral|Psychology, Clinical http://docs.lib.purdue.edu/dissertations/AAI3544359 http://docs.lib.purdue.edu/dissertations/AAI3544359 Wed, 22 May 2013 15:50:46 PDT Buildings were responsible for 41% of the primary energy use in the United States in 2011. If the energy consumed in the building section was broken down by end-users, it were about 21% and 13% of primary energy used for space heating and space cooling respectively. Ground-couple heat pump (GCHP) systems use stored energy in the ground at a relatively constant temperature as a heat source (in the winter) and a heat sink (in the summer) so that they offer higher energy efficiency than the conventional heating and cooling system. However, drilling of deep boreholes comes with a high initial cost, which hinders the application of the GCHP systems. To effectively use a GCHP, it is necessary in the design phase to accurately predict the thermal performance of GCHP systems throughout their entire life spans. ^ This research aims to develop the heat conduction model and the hybrid moisture and groundwater model for vertical U-tube ground heat exchangers (GHEs) to evaluate its performance within their life spans. Based on these models, the sensitivity analysis will be conducted to study the influence of parameters on the thermal performance of vertical U-tube GHEs. In order to achieve this goal, it can be broken down to three sub-objectives: ^ • Objective 1: Develop the two-dimensional heat conduction model for constant volume and variable volume vertical U-tube GHEs in cylindrical coordinate system. • Objective 2: Develop hybrid moisture and groundwater model in the three-dimensional unstructured grid to consider the influence of the moisture transfer and groundwater movement on the thermal performance. • Objective 3: Conduct the sensitivity analysis of the parameters on the performance of vertical U-tube GHEs. The screening design will select the relatively important parameters and the sensitivity analysis will rank these screened parameters. The result of sensitivity analysis will provide the guidance for further optimization of the model of vertical U-tube GHEs. ^ Based on the local geological surveys or the data from testing boreholes, the models developed in this research will significantly help designers to predict the thermal performance of GCHP systems. The appropriate design for the GCHP systems will be achieved to trade off the initial cost and the operating cost in their life spans. In the future research, the models of vertical U-tube GHEs could be integrated with the models of cooling towers or solar collectors to simulate the hybrid GCHP systems, which provide much higher efficiency for the thermally imbalanced buildings.^

]]> Wei Ruan Engineering, Civil|Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI3544357 http://docs.lib.purdue.edu/dissertations/AAI3544357 Wed, 22 May 2013 15:50:45 PDT Cooperative robotics is concerned with the simultaneous utilization of multiple robots and promises a number of advantages, including increased robustness, decreased complexity of the robots themselves, and, through synergistic effects, better execution of a task over a single, similarly capable robot. The task of object transportation is especially well suited to cooperative robots since large, bulky items that require correspondingly large handling devices can instead be supported by several significantly smaller robots. Due to their inherently limited resources, mobile robots benefit the most from cooperation. ^ For the task of object transportation, a unique type of mobile robot is presented which, when part of a group, is able to lift and carry objects that may be considerably larger than itself. A key feature of the presented robot is that it is devoid of articulated mechanisms, and instead interacts with objects through the non-grasping, frictional contact of wheels. This ultimately allows the robot to transport objects without any special features or fixturing points, and by way of relative motion, allows for unique motions that permit traversal across cluttered, unstructured terrain. ^ To determine when such a robot can lift an object, a static force analysis is initially performed. Through the use of contour plots, maps of configurations where the process is feasible are generated, allowing quick visual inspection of the robot's ability to lift objects. In order to quantitatively demonstrate that a group of these robots are physically capable of controlling an object, a new formulation for robotic grasp analysis is established as well. This technique can be used to find the best set of joint torques that optimizes an arbitrary metric, even when the robots are kinematically deficient and redundancies exist. Beyond the team of robots addressed in this work, the technique is generalizable to any multi-contact problem, such as robotic hands, fixtures, and whole-arm grasps. ^ To control the team of the proposed robots, a behavior-based control scheme is devised for a lifting maneuver and an extension of the artificial potential field method is developed for cooperative carrying of an object. These control strategies do not rely on a single controller, but instead allow each robot of the team to determine its motions independently, making the team scalable to an arbitrary number of robots. The strategies are then tested through a number of dynamic simulations, showing that the process is robust to errors and benefits from the use of many robots.^

]]> Tyson L Ringold Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI3544353 http://docs.lib.purdue.edu/dissertations/AAI3544353 Wed, 22 May 2013 15:50:43 PDT Research on teaching efficacy suggests that in comparison to instructors with lower teaching efficacy, instructors with higher teaching efficacy are more willing to take responsibility for student failure, more likely to expect failing students to succeed in subsequent performance, and more willing to help failing students. Those findings are primarily based on research in K-12 settings. This study expanded on existing research by exploring the mentioned differences between instructors with lower and higher teaching efficacy in a higher education setting. Instructors at a comprehensive public university with a primary focus on undergraduate education completed a survey in which they indicated their likely responses to failing students in two different case scenarios. ^ Instructors' responses to the survey were analyzed via multiple linear regression with part correlations to determine the effect of teaching efficacy on each of the three dependent variables after controlling for instructors' perception of the stability of the failure cause, instructors' perception of student control over failure, and instructors' gender, rank, and years of teaching experience. Results of the study showed a statistically significant effect of teaching efficacy on instructors' willingness to provide proactive help to the failing student in both case scenarios. However, the effect of teaching efficacy on instructors' willingness to take responsibility for student failure, their expectancy of students' success in future performance, and their willingness to provide reactive help was mixed for the two case scenarios, producing a statistically significantly effect in only one of the two case scenarios for each of the three dependent variables. ^ Results from the study suggest that the context of student failure has a mitigating influence on how instructors' sense of teaching efficacy impacts their reaction towards failing students. Potential reasons for the mitigating effect of failure context are discussed.^

]]> Christian Reiner Education, Teacher Training|Education, Higher http://docs.lib.purdue.edu/dissertations/AAI3544355 http://docs.lib.purdue.edu/dissertations/AAI3544355 Wed, 22 May 2013 15:50:43 PDT The objective of this research is to develop and apply single-laser-shot femtosecond (fs) coherent anti-Stokes Raman scattering (CARS) as a laser diagnostic technique for temperature and concentration measurements in flames. The main potential advantage of this technique is that measurements can be performed at data rates of greater than 1 kHz. Advances in fs laser technology have led to commercially available fs laser systems with repetition rates of 1-10 kHz and pulse energies of a few millijoules (mJ). By developing single-laser-shot techniques with such laser systems, measurement data rates at least two orders of magnitude higher those associated with typical nanosecond Nd:YAG lasers become possible. Such high data rate measurements will provide new insight into transient and turbulent events, reduce testing time for experiments, and eventually aid in the design and evaluation of new combustion devices. ^ A theoretical model and fitting routine have been developed to extract temperature and concentration measurements by comparing theoretical and experimental spectra. The electric fields are modeled by incorporating the experimentally measured spectrum of the pump, Stokes, and probe pulses and assuming a polynomial spectral phase. The resonant and nonresonant polarizations induced at the probe volume are modeled using the electric fields and Raman transition information. Finally, the CARS signal is modeled as the product of the chirped probe pulse electric field with the resonant and nonresonant polarizations. All fitting routines used to compare experimental and theoretical spectra use a genetic algorithm called differential evolution. Values for the laser parameters in the theoretical model are obtained by fitting a calibration spectrum recorded at a known temperature or concentration. These parameters are then held constant while fitting single-laser-shot spectra recorded in a test section. ^ Fs CARS temperature measurements at 1 kHz have been performed in a heated gas cell, laminar near-adiabatic hydrogen-air flames, driven flames, and turbulent methane-air flames. For all flame temperature measurements, the precision was better than 2% of the average measured temperature. The accuracy of the measurements is strongly dependent on accurate models for the electric fields of the laser pulses, and is typically better than 3% of the absolute temperature over the temperature range from 300 to 2400 K. In driven flames the measured temperature is in good agreement with the expected temperature deviations. ^ Polarization suppression of the nonresonant background has been demonstrated for single-laser-shot temperature measurements at 5 kHz in steady and unsteady flames. By suppressing the nonresonant background the evolution of the Raman coherence near zero probe time delay is more clearly revealed. The structure of the CPP fs CARS spectra with and without nonresonant background suppression is compared. The utility of polarization suppression of the nonresonant background for CPP fs CARS measurements is discussed. Flame temperature fluctuations over the range of 500 to 1800 K are measured in turbulent diffusion flames. ^ Concentration measurements have been performed at 1 kHz using fs CARS in argon-nitrogen and carbon monoxide-nitrogen binary gas mixtures in a heated gas cell from 300 to 900 K at atmospheric pressure. The broadband pump and Stokes pulses excite Raman transitions in both the carbon monoxide and nitrogen. For measurements in argon-nitrogen or carbon monoxide-nitrogen gas mixtures, concentration measurements could be performed over the range of 5% - 90% nitrogen with typical measurement error being less than 2.0% in absolute concentration. The precision of the measurements was typically better than 1.5% in absolute concentration. Polarization suppression of the nonresonant background is also demonstrated for concentration measurements. Nonresonant background suppression clearly reveals the resonant signals from each gas species and concentration measurements could be performed over a slightly reduced concentration range with comparable results. (Abstract shortened by UMI.)^

]]> Daniel R Richardson Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI3544351 http://docs.lib.purdue.edu/dissertations/AAI3544351 Wed, 22 May 2013 15:50:41 PDT Research indicates that posttraumatic stress disorder (PTSD) negatively affects the romantic relationships of service members and their partners; however, few studies have identified or examined moderators of the relationship between PTSD and relationship satisfaction. The current study examined the association between partner's relationship satisfaction and soldier's self-reported PTSD, and whether this link was moderated by intimate partner's perception of the soldier's combat exposure. It was expected that partner's perceptions of soldier's combat exposure would moderate the relationship between soldier's PTSD and partner's satisfaction such that when partners perceived low levels of combat exposure, soldier's PTSD would be negatively associated with partner's relationship satisfaction. Data were draw from a longitudinal study of National Guard soldiers and their intimate partners (N = 52 couples). Participants provided data on self-reported symptoms of posttraumatic stress disorder, combat exposure (perceived and experienced), service use, and relationship satisfaction at two time points (4 months and 1 year) following the soldier's return from deployment. Partner's perception of soldier's combat exposure did not moderate the relationship between soldier's PTSD and partner's relationship satisfaction at either time point. Soldier's use of available services also did not moderate the relationship between soldier's PTSD and partner's relationship satisfaction at either measurement occasion. These findings as well as the results of exploratory analyses are presented and areas of future research are suggested.^

]]> Elizabeth S Rayl Psychology, Social|Psychology, Clinical http://docs.lib.purdue.edu/dissertations/AAI3544350 http://docs.lib.purdue.edu/dissertations/AAI3544350 Wed, 22 May 2013 15:50:40 PDT The purpose of this qualitative study was to describe the lived experiences of primary classroom teachers participating in collaborative data-driven decision making. Hermeneutic phenomenology served as the theoretical framework. Data were collected by conducting interviews with thirteen classroom teachers who taught in grades kindergarten through third grade who participated in collaborative data-driven decision making with their grade level team. Those interviews were audio recorded and transcribed. Item analysis was performed on the individual interviews and data were placed into a matrix. The matrix was then validated and unfolded during interviews with each team. ^ The study focused on two questions. First, what is the experience of the classroom teacher as he or she participates in collaborative data-driven decision making? And second, how do teachers feel about collaborative data-driven decision making in practice? ^ As a result of the study, eight themes emerged as the central experiences of teachers participating in collaborative data-driven decision making. Those themes included: Data, Team Dynamics, Collaboration, Efficacy, Time, Paperwork, Administration and Professional Development. Themes were identified through the analysis of the overall experience of the participant group of thirteen primary grade teachers representing four grade level teams. ^ While commonalities exist among the themes, the overall experience of the participants identified both benefits of and barriers to effective collaborative data-driven decision making. This study has implications for schools that are currently implementing a collaborative data-driven decision making model, or for schools or districts that are considering utilizing a collaborative data-driven decision making model for continuous school improvement. Keywords: collaboration, data, data-driven decision making, hermeneutic, phenomenology, PLC, professional learning community, problem solving, response to intervention, RTI.^

]]> Christine R Ralston Education, Leadership|Education, Administration|Education, Elementary|Education, Teacher Training http://docs.lib.purdue.edu/dissertations/AAI3544349 http://docs.lib.purdue.edu/dissertations/AAI3544349 Wed, 22 May 2013 15:50:40 PDT Atomic level thermal transport in layered materials, namely, Bi ₂Te₃ and graphene is investigated using first principles calculations, lattice dynamics (LD) calculations, molecular dynamics simulations, spectral phonon analysis and empirical modeling. These materials resemble geometrically while differ significantly in the nature of thermal transport. Because of their uniquely low/high thermal conductivities, they are of great interest in thermoelectrics and thermal management applications, respectively. Besides Bi₂Te₃ and graphene, many other materials in the family of layered materials also exhibit great promises for various applications in thermoelectrics, thermal management, and electronics. In order to investigate the thermal properties of general layered materials, we explore the use of tight-binding molecular dynamics (TBMD) approach, which neither relies on the availability of classical potentials nor demands significant computational resources as ab initio MD approach does. In addition, a general model for the effective phonon group velocities, which is relevant for the lattice thermal transport in general few-layer materials, is developed. ^ First of all, two-body interatomic potentials in the Morse potential form have been developed for bismuth telluride. The density functional theory with local-density approximations is first used to calculate the total energies for many artificially distorted Bi₂Te₃ configurations to produce the energy surface. Then by fitting to this energy surface and other experimental data, the Morse potential form is parameterized. The fitted empirical interatomic potentials are shown to reproduce the elastic and phonon data well. With the classical interatomic potentials developed, molecular dynamics simulations are performed to predict the thermal conductivity of bulk Bi₂Te₃ at different temperatures, and the results agree with experimental data well. ^ To facilitate phonon-engineering, we predict the thermal conductivity of Bi₂Te₃ nanowires with diameters ranging from 3 to 30 nm with both smooth and rough surfaces. It is found that when the nanowire diameter decreases to the molecular scale, the thermal conductivity shows significant reduction as compared to bulk value. On the other hand, the thermal conductivity for the 30-nm-diam nanowire only shows less than 20% reduction, in agreement with recent experimental data. Also, the thermal conductivity of nanowires shows a weaker temperature dependence than the typical T ^–1 trend, consistent with experimental observations. This is attributed to the strong boundary scattering of phonons. ^ Being motivated by the recent experimental exfoliation of atomically-thin Bi₂Te₃ flakes, thermal conductivity of perfect and nanoporous few-quintuple Bi₂Te₃ thin films as well as nanoribbons with perfect and zig-zag edges is investigated using molecular dynamics (MD) simulations with Green-Kubo method. We find minimum thermal conductivity of perfect Bi₂Te₃ thin films with three quintuple layers (QLs) at room temperature. Nanoporous films and nanoribbons are studied for additional phonon scattering channels in suppressing thermal conductivity. ^ So far we have studied the lattice thermal conductivity of Bi₂Te ₃ bulk and important nanostructures. To understand the detailed phonon transport, dominant phonon modes and how various nanostructures can efficiently alter the thermal conductivity in Bi₂Te₃ through phonon scattering, we further study the mode-wise phonon properties in Bi₂Te ₃ using spectral energy density approach (SED). The anharmonic phonon dispersions and relaxation times along Γ – Z direction are extracted. To validate the as-obtained spectral properties, the lattice thermal conductivity in the cross-plane direction is obtained under isotropic approximation, which is found to agree with Green-Kubo predictions well. (Abstract shortened by UMI.)^

]]> Bo Qui Engineering, Mechanical|Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI3544234 http://docs.lib.purdue.edu/dissertations/AAI3544234 Wed, 22 May 2013 15:50:37 PDT The first essay examines whether online companies can charge fees for online content. We investigate this issue for an online gaming company which decided to move from free subscription to paid subscription. In essence, this company decided the optimal strategy in a two-sided market where it collects revenue from advertisers and from subscribers. The demand model is a random coefficient logit system and the supply model is a forward looking system. The company makes its decision based on the demand that it observes, i.e., the demand model is estimated first and then the demand parameters are used to project the market in the supply model. This study finds that the online gaming content is an area where consumers are willing to purchase. If the advertising revenue is insufficient, the company is better off by being a paid subscription provider, on the other hand the company should remain a free subscription provider if the advertising revenue is sufficiently high. The advertising revenue level for this threshold point is about $0.60 per week by a subscriber. In a paid subscription system, paid subscribers value paid subscribers for gaming activities and free subscribers value free subscribers for communities and sharing of information. Therefore, it is important to have a good gaming offering for the paid subscribers and good non-gaming offerings for the free subscribers. ^ The second essay examines tradeoff between the benefits of long term commitment and the uncertainty of short term commitment. We study an online company that offered various subscription terms that had different commitment lengths. We use the two-stage estimation of the discrete-continuous choice model to investigate this issue. The discrete choice was whether or not the subscriber purchased subscription plans or gaming items and the continuous choice was the number of purchases for these gaming items. We notice that the two mid-term commitments do not have preferable values over the shorter or longer commitment plans. Thus, the subscribers for our focal online content do not seem to take advantage of the long term contracts. Although there are no price advantages for longer commitment lengths, the usage of gaming items show similar decreasing purchase patterns since the initial purchase among commitment lengths. The heterogeneity variables show significance for the subscription plans but show no significance for subscription length, i.e., the company is not correctly segmenting the subscribers. Therefore, the tradeoff between long term vs. short term commitment does not seem to be aligned for both gaming item usage and subscription length of subscribers.^

]]> Jinsuh Lee Business Administration, Marketing|Web Studies http://docs.lib.purdue.edu/dissertations/AAI1535739 http://docs.lib.purdue.edu/dissertations/AAI1535739 Wed, 22 May 2013 15:46:16 PDT According to the action-specific perception account, spatial perception is affected by the specific energetic cost required to perform an action. Hills were judged as steeper to people who are wearing a heavy backpack, are fatigued, or are elderly (Bhalla & Proffitt, 1999). In the current experiments, we examined the effect of age on distance perception. Older and younger adults were asked to verbally estimate distance to a target placed in a hallway. Results showed that older adults estimated distances to be farther compared to younger adults, but only for action-relevant extents. Additionally, when subjects were asked to estimate distances on a carpet and a plastic surface, the types of floor surfaces that decrease walking ability, such as plastic tarps, were judged to be farther away for older adults while such sensitivity was not as apparent in younger adults. The results suggest that perception is still sensitive to differences that affect ability even as a perceiver ages.^

]]> Mila Sugovic Health Sciences, Aging|Psychology, Cognitive http://docs.lib.purdue.edu/dissertations/AAI1535180 http://docs.lib.purdue.edu/dissertations/AAI1535180 Wed, 22 May 2013 15:46:15 PDT Because of their unique one dimensional structure, large surface area, and electronic properties, single wall carbon nanotubes (SWCNTs) have been extensively studied for multiple applications, including electronics, biosensors, and solar energy harvesting. With charge separation ability and conductivity, semiconducting carbon nanotubes are applied as charge acceptors and structural frames in donor-acceptor solar cells. Herein, novel light harvesting nanohybrids in donor-acceptor systems are designed to study photo-conversion processes. DNA oligonucleotides with molecular recognition capabilities are used to tether charge donors (chromophores), while non-covalently adsorbing carbon nanotubes. Four types of porphyrin chromophores are studied for their optical electrochemical properties: singlet and triplet excited states, and redox potentials. These properties can directly affect the photo-conversion processes in nanohybrids. To understand the photo-conversion processes, steady state absorption and emission titration and excited state lifetime measurements are performed to understand the photo-conversion processes. Photo-induced charge transfer is observed in the nanohybrids. Deposited nanohybrid films are examined in a photoelectrochemical cell, and photocurrents are measured. Effects of electrolyte conditions on photocurrent are also studied.^

]]> Hanyu Zhang Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1535707 http://docs.lib.purdue.edu/dissertations/AAI1535707 Wed, 22 May 2013 15:46:15 PDT This study consists of two discrete topics important to the design of two-phase cooling systems, fin-and-tube condensers and spray cooling modules. ^ The first part describes a comprehensive method for predicting pressure drop and thermal performance of three different types of fin-and-tube condensers. Detailed airside heat transfer coefficient condensation side, a series of correlations for the laminar/turbulent single-phase cooling regions and two-phase condensation region are presented. Finally, a step-by-step method to predict the pressure drop and heat transfer characteristics of the condenser is presented. ^ The second part describes the design of spray cooling modules. A detailed design methodology for spray cooling is represented. The key goal of this methodology is to minimize surface temperature while maintaining surface heat flux safely below critical heat flux (CHF). Presented in this part are detailed models and correlations for the spray's Sauter mean diameter, volumetric flux distribution, nucleate boiling heat transfer coefficient, and CHF. These tools are integrated into a comprehensive design methodology to enable the configuration and thermal optimization of a spray-cooling module.^

]]> Hyoungsoon Lee Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1535179 http://docs.lib.purdue.edu/dissertations/AAI1535179 Wed, 22 May 2013 15:46:14 PDT In recent years the introduction of location-based services in online social networks have provided unprecedented amount of public-generated data on human movements and activities. This novel data source is available for free and provides a new dimension of information related to human activities with greater details. Investigating urban activity pattern is crucial for understanding the driving force behind human movements in urban areas. Most of previous studies focus on understanding and modeling human mobility using data collected from mobile phones, bank notes movements, and subway smart-card transactions. However, these studies fail to link human movements with their purposes (activities). Although other studies use the combination of mobile phone data and Point of Interest (POI) data collected from internet, the information from POI for each place does not necessarily correspond to the actual activity that individual is participating in. In this research, the location-based information ("check-ins") shared in an online social media, i.e., Twitter, is used to explore and interpret the aggregate level urban activity pattern. With detailed activity categories in each data record, we are able to discover more realistic and detailed description of human dynamics and urban activity characteristics. ^ The first goal of this research is to investigate the urban aggregate level activity pattern. In this work, the individual check-in behavior is analyzed, which shows that the individual number of check-ins follows a truncated power law distribution and the individual radius of gyration follows a Weibull distribution. The temporal characteristics are also investigated, which reveals distinct patterns in different activity categories. In order to study the data at more detailed level, a virtual grid is constructed by dividing the city map into square cells at the size of 200 by 200 meters. Using the grid system, we can visualize the spatial distribution of popular places, and compute the site ranking distribution for the cells. These spatial distributions show important features about the unique activity patterns for each city. The kernel density estimation technique is also applied to reveal the evolution of activity centers in both time and space. Same analysis is conducted in New York, Chicago, Los Angeles and San Francisco, where city level activity patterns are compared. The findings show the existence of underlying laws and patterns that govern human urban activities, which enhance our understanding about the urban dynamics and human movement in the urban area. ^ The second goal of this study is to explore the possibility of using this new type of data to infer the urban land use. A new approach of using unsupervised clustering algorithm and social media check-in data is proposed. Data is aggregated and normalized by time periods and activity categories for each cell. K-means algorithm is then used to cluster all the cells into four classes. Optimal number of clusters and empirical verification confirm that this approach can effectively predict the residential, commercial, open space and recreation sites with reasonable accuracy. This shows the potential of using large scale geo-location data in urban land use inference.^

]]> Xianyuan Zhan Engineering, Civil|Transportation http://docs.lib.purdue.edu/dissertations/AAI1535177 http://docs.lib.purdue.edu/dissertations/AAI1535177 Wed, 22 May 2013 15:46:13 PDT The present study aims to identify the perceptions of local traveler contact people regarding luxury international and luxury domestic hotels in China when they are recommending local luxury hotels to travelers. An extensive literature review indicated a need for further research in the field related to referral behavior, brand perception, and comparison of international brands versus domestic brands. A total of 307 local people in Nanjing were surveyed and the number of usable questionnaires was 220. Those surveyed include taxi drivers, secretaries, travel and convention/exhibition agency staff, and others involved in lodging referrals due to direct requests of travelers. To answer the research questions, factor analysis, multiple regression, and logistic regression were conducted. Results indicated that gender, income, educational level, and job category are the main factors that affect traveler contact people's perceived hotel image. Additionally, local traveler contact people's recommendation preferences were significantly affect by hotel culture-related background, reputation, and what benefits the hotel provided. The findings have practical implications for improving local people's brand perception toward both international hotel brands and domestic hotel brands.^

]]> Dan Xue Business Administration, General|Asian Studies|Recreation http://docs.lib.purdue.edu/dissertations/AAI1535178 http://docs.lib.purdue.edu/dissertations/AAI1535178 Wed, 22 May 2013 15:46:13 PDT In recent years, domestic natural gas production has increased markedly, and now has the potential to become a cleaner and less expensive energy source than diesel fuel for use in the public transportation sector. Also, in the face of increasing diesel fuel costs and increasing concerns regarding air emissions caused by its fleet, Lafayette CityBus Corporation is examining long-term fuel alternatives to maintain its current level of services. ^ This study uses benefit-cost analysis to compare the total cost of three potential options for bus replacement. The candidate systems are standard diesel, hybrid diesel-electric and compressed natural gas (CNG). In addition, the environmental costs of these three fleet options are estimated. ^ There are two main components of total cost: operating cost and capital cost. This study analyzes and compares the costs among the three candidate systems over a 15-year project horizon. Results suggest that the CNG option has the lowest net present value (NPV) of total cost, and that cost savings would be larger if the corporation could obtain a grant for the CNG fueling station or if the project lifespan could expand to 20 years. The CNG option would produce the least amount of emissions and largest environmental benefit. ^ Monte Carlo simulation is used to examine the inherent riskiness of the three fleet options. CNG is always lower cost than hybrid diesel-electric. Depending on assumptions regarding the underlying price distributions, the CNG option has a 51 to 79 percent chance of being lower cost than the standard diesel option. With a 20-year project horizon, the CNG option has a higher probability of being lower cost.^

]]> Lin Yang Economics, Agricultural http://docs.lib.purdue.edu/dissertations/AAI1535176 http://docs.lib.purdue.edu/dissertations/AAI1535176 Wed, 22 May 2013 15:46:12 PDT The layout of a remotely piloted vehicle (RPV) flight instrument display was evaluated. An eye tracking system was employed to record pilots' eye movements while they perform two tasks in a computer simulated control environment. Fixation duration and fixation frequency were calculated for each flight instrument. Link analysis was conducted to evaluate the frequency of eye movement transitions between each pair of instruments. ^ There were several major findings: 1) the heading indicator, which was a numeric indicator, was easier to interpret than some of the flight instruments that used moving textbox symbology, and thus suggested that the moving textbox symbology did not function well in providing qualitative cues as it was designed for; 2) the attitude indicator was the most important instrument and 3) the locations of the attitude indicator, airspeed, and heading indicator on the flight display were adequate, but the altitude indicator should be placed closer to the attitude indicator as compared to the vertical speed indicator and RPM.^

]]> Shan Xie Engineering, Industrial http://docs.lib.purdue.edu/dissertations/AAI1535174 http://docs.lib.purdue.edu/dissertations/AAI1535174 Wed, 22 May 2013 15:46:11 PDT With the rapid and sustained economic growth since the Reform and Opening of 1978, Chinese travelers have become a substantial market segment of the resort industry. As the first generation born after the Reform and Opening and the One Child policy, China's Generation Y, or the Post-80s generational cohort has entered into young adulthood and begun to play major roles on the social stage as employees, future leaders and for sure, consumers. However, few empirical resort studies have targeted this generation. This research investigates China's Post-80s consumers and their attribute preferences in resort selection. In addition, the study also compares the Post-80s with previous generations in resort consumption, attribute preferences and personal values and explores an explanation of the Post-80s resort attribute preferences and possible generational differences through an investigation of the relationship with personal values. Quantitative data were collected through a web-based survey with Chinese resort consumes. The results suggest that not many significant differences were found between the Post-80s and their predecessors in resort consumption and attribute preferences and the Chinese resort market is relatively homogeneous. Unlike traditional western resort vacationers, Chinese resort consumers stay at resort for a short period and engage in tourism activities such as sightseeing more than resort activities. When selecting resort, both the Post-80s and previous generations attach most importance to resort quality and basic hotel attributes and least importance to resort-featured entertainment and recreational facilities and programs. This can be linked to the confounding influence of the shared traditional Chinese values among the Post-80s and their predecessors, such as pursuing a sense of security, self-esteem, social status, group orientation, and conservatism. Despite, the study also found that compared with previous generations, the Post-80s are more influenced by western values and are more self-oriented. They place higher importance on resort ambience, room features, and efficiency and are willing to pursue their self-identity, personal pleasure and enjoyment, and interaction with others through those attributes. Theoretical contributions, pragmatic implications, and limitations and recommendations for future studies are discussed at last. ^

]]> Xin Wen Business Administration, Marketing http://docs.lib.purdue.edu/dissertations/AAI1535175 http://docs.lib.purdue.edu/dissertations/AAI1535175 Wed, 22 May 2013 15:46:11 PDT Laser direct deposition provides an attractive and cost effective means for enhancing or remanufacturing high value engineering components. This study demonstrates the successful repair of defective voids in turbine airfoils based on a new semi-automated geometric reconstruction algorithm and a laser direct deposition process. A Boolean difference between the original defective model and the final reconstructed model yields a parameterized geometric representation of the repair volume. The experimental results of this method demonstrate the effectiveness of laser direct deposition in remanufacturing and its potential to adapt to a wide range of part defects. A Life Cycle Assessment (LCA) on the energy and environmental impacts by remanufacturing is also presented. Functionally graded material improves components performance over the original parts. ^ Functionally gradient material (FGM) can be tailored to the structural requirements of the final product. In this study, titanium carbide (TiC) reinforcement particles were embedded in Inconel 690 with laser direct deposition to build functionally gradient metal matrix composites (FGMMCs). The microstructures of the MMC and distribution of TiC particles were characterized with an optical microscope, SEM and X-ray diffraction. There was a near absence of internal voids in the deposited TiC-Inconel 690 MMC. With the volume percentage of TiC particles in the depositions varied from 0 to 49%, a drastic evolution in the microstructure was observed and the presence of TiC particles over 30% yielded a refinement of the matrix microstructure and introduction of a finely dispersed crystalline phase. High-temperature dissolution of TiC was not detected under the conditions used. Micro-hardness and wear resistance tests showed a significant improvement with increased TiC content. ^ Functionally gradient bio -coating material was built by laser deposition. Co-Cr-Mo material was deposited on a Ti-6Al-4V substrate transitioning from 0 to 100%. Control over the cooling rate is shown to be a key to reduce the effects of thermal expansion differences of the materials. The microstructures and composition of the functionally gradient material (FGM) were characterized using an optical microscope, SEM, EDS and XRD. EDS results showed a gradual transition to 50% Co-Cr-Mo and ∼100% Co-Cr-Mo on the top layer. XRD analysis showed the absence of a brittle intermetallic phase that forms between Titanium and Cobalt. As the amount of Co-Cr-Mo increased, the microhardness of the FGM samples significantly increased. A comparison was made between Co-Cr-Mo deposited on SS316L substrates as well as Ti-6Al-4V. The bonding strength of the coatings on both substrates was tested and found to meet the ASTM standard requirement.^

]]> Jon Michael Wilson Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1535173 http://docs.lib.purdue.edu/dissertations/AAI1535173 Wed, 22 May 2013 15:46:10 PDT In recent years, On-Board-Diagnostics regulations have put more emphasis on reducing nitrogen oxide emissions and detecting and diagnosing faults in diesel engines. It is beneficial to investigate techniques to solve this problem. An algorithm called Sparse Linear Discriminant Analysis (SLDA) can be used to select relevant sensor signals in the detection and classification of faults. The work in this thesis applied those methods to data collected from three similar but separate engines used in the field that incurred identical faults. Healthy and faulty data samples were collected from each truck, and the data was processed to reduce selection bias between the two samples. The SLDA algorithm was then used on the processed data to select the most relevant sensor signals that defined the separation between healthy and faulty data. A classification algorithm was then used to determine the accuracy of the classifier. The combined use of the algorithms classified healthy data from faulty data with an accuracy of greater than 90%. The success of the methods used in this work shows the potential for real time implementation on engines in the field.^

]]> Benjamin A Warman Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1535171 http://docs.lib.purdue.edu/dissertations/AAI1535171 Wed, 22 May 2013 15:46:09 PDT Comparative analyses of candidate second generation biomass species are needed to understand the hydrologic, agronomic, and environmental impacts of species deployment for biomass production. Our objective was to quantify tile drain event volume, nitrate concentrations and load for upland switchgrass (c.v. Shawnee), Miscanthus x giganteus, and big bluestem (Andropogon gerardii) dominant mixed prairie, as well as tilled continuous maize (Zea mays L.) control. Data from large, in-ground lysimeters at the Purdue University Water Quality Field Station near West Lafayette, IN were used from plots on soils characterized predominantly as Drummer silty clay loam. This included hourly drain flow collected from 265 m² clay-lined lysimeters over a sixteen year period (1995–2011). Nitrate concentration samples were collected as a mixed composite of tips accumulated every 24 to 72 hours during storm events from 1998–2011. A paired regression analysis was used to mitigate environmental and climatic impacts on inter-tile variability to quantify shifts in total event flow. Miscanthus-transitioned tile mean event flow decreased significantly at p≤0.20, while switchgrass-transitioned tile response varied across replicates, including significant decreases (p≤0.10) and significant increases (p≤0.05) in mean event flow. Average nitrate concentration decreased significantly in response to switchgrass and Miscanthus cropping system transitions. ^ Nitrate concentrations were significantly lower in Miscanthus -transitioned tiles compared to switchgrass and mixed prairie system tiles once plants were established. Cumulative event nitrate loads were also significantly lower for all perennial plots compared to continuous maize control. Results suggest that although transition into switchgrass and Miscanthus predominantly decreases total event flow, increases in tile drain event flow may be observed due to site-specific conditions including preferential flow. Perennial crops decreased tile nitrate concentrations significantly, which resulted in significantly lower net load from perennial system tile drains.^

]]> Elizabeth Trybula Agriculture, Agronomy|Hydrology|Engineering, Agricultural http://docs.lib.purdue.edu/dissertations/AAI1535172 http://docs.lib.purdue.edu/dissertations/AAI1535172 Wed, 22 May 2013 15:46:09 PDT The skeletal muscle is a complex tissue mainly composed of a mixture of fast and slow myofibers. The ratio of fast and slow myofibers is built to achieve specific physiological functions and is developed under the control of intrinsic and extrinsic factors. Understanding how myofibers are specified during development and regeneration has several important implications. This project aims to dissect the genetic basis of fast and slow myofiber specification using transgenic mouse models. These mouse models serve as efficient tools for labeling myofibers concurrently expressing fast or slow myosin heavy chain (Myh), or marking myofiber lineages derived from myogenic precursor cells that have once activated fast or slow myosin. Using the lineage labeling mouse model, it was shown that all nascent myofibers unanimously express the slow myosin Myh7 during muscle regeneration. Upon completion of regeneration, however, fast myofibers downregulate Myh7 expression to restore the stereotyped distribution pattern of fast and slow myofibers in the regenerated muscle. In contrast to the ubiquitous expression of Myh7 during regeneration, only a subset of mature fast myofibers had activated the slow Myh7 gene expression during normal development. Moreover, a single mature fast or slow myofiber can be fused from a mixture of precursor cells with different pattern of myosin gene activation. Combining cell lineage tracing and cell culture techniques, the fate of myoblasts that activated the slow muscle specific Myh7 gene was examined. In striking contrast to the dogma that myosin genes are only expressed in terminally differentiated cells, it was shown in this study that myogenic progenitors (myoblasts) activated Myh7 can still proliferate and express Pax7, known to be expressed only in myogenic progenitor but not differentiated cells. Furthermore, the Myh7 activated myoblasts were not limited to become slow muscles, though they had a higher tendency to do so. Together, this study provides compelling evidence that Myh7 can be activated in myogenic progenitors, and that the activation pattern of Myh7 is different during development and regeneration. These results provide novel insight into the regulation of muscle fiber type specification.^

]]> Qiaojing Wang Agriculture, Animal Culture and Nutrition http://docs.lib.purdue.edu/dissertations/AAI1535170 http://docs.lib.purdue.edu/dissertations/AAI1535170 Wed, 22 May 2013 15:46:08 PDT In the United States, visual observations of tornadoes and/or the existence of tornado damage currently provide the sole evidence of tornadogenesis in association with a mesocyclone or other radar-detected storm-scale vortex. The severity of the tornado damage is currently the only means of estimating the intensity of tornadoes, radar-detected or otherwise. The limitations of the damage-based record of tornado occurrence and intensity are well-known and motivated this research. ^ WSR-88D measurements of the translating tornadic flow were compared to (semi-) coordinated measurements obtained near the surface with mobile radar. Based on a small yet fairly broad sample of tornadoes, high linear correlation was found between the vortex intensity (rotation plus translation) quantified using Weather Surveillance Radars-1988 Doppler (WSR-88D) data and that quantified using Doppler on Wheels (DOW) data. The possible effects of Doppler radar sampling on these results were explored through experiments with a simple vortex model. These experiments argued that the likelihood is high that a tornado would be sampled in a favorable way during at least one radar scan. Hence, the suggestion from this work is that WSR-88Ds (or similar operational radars) can potentially be used in isolation to estimate low-level tornado intensity. The proposed estimation is by way of a linear regression model, and application of this model is relevant only once a tornado is already confirmed. ^

]]> Mallie Elizabeth Toth Meteorology|Atmospheric Sciences http://docs.lib.purdue.edu/dissertations/AAI1535169 http://docs.lib.purdue.edu/dissertations/AAI1535169 Wed, 22 May 2013 15:46:07 PDT Sub-critical intergranular crack growth is an important creep fracture mechanism in polycrystalline superalloys. The root cause of this fracture is not well understood. The role of grain orientation on the formation of sub-critical grain boundary cracks during creep of a conventionally cast nickel-based superalloy has been analyzed in this study. The crystallographic orientations of grain pairs adjacent to grain boundaries normal to the tensile axis were measured using Electron Back-Scattered Diffraction (EBSD). The difference in the Schmid factor for the {111} <112> slip system between the grains was compared to the occurrence of sub-critical grain boundary cracking. In addition, the difference in the amount of potential primary creep strain between the grains (for unconstrained state) was analyzed. The uncracked grain boundaries were found to have small Schmid factor mismatch, as well as small potential primary creep strain mismatch, than those of the cracked grain boundaries. Larger mismatches in Schmid factor and potential primary creep strain indicate possible development of large enough stress concentration at the grain boundary sufficient to initiate sub-critical cracks. The experimental results suggest correlations between crystallographic orientation of the grains and sub-critical cracking at the grain boundary with a critical value for Schmid factor mismatch and potential primary creep strain mismatch in the creep tested alloy. Assumptions and limitations are considered in proposing future experiments for further refinement of the analysis.^

]]> Kameshwaran Swaminathan Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI1535168 http://docs.lib.purdue.edu/dissertations/AAI1535168 Wed, 22 May 2013 15:46:06 PDT The United States National Airspace System (NAS) network performance is currently measured using a variety of metrics based on delay. Developments in the fields of wireless communication, manufacturing and other modes of transportation like road, freight, etc. have explored various metrics that complement the delay metric. In this work, we develop a throughput concept for both the terminal and en-route phases of flight inspired by studies in the above areas and explore the applications of throughput metrics for the en-route airspace of the NAS. These metrics can be applied to the NAS performance at each hierarchical level—the sector, center, regional and national and will consist of multiple layers of networks with the bottom level comprising the traffic pattern modelled as a network of individual sectors acting as nodes. This hierarchical approach is especially suited for executive level decision making as it gives an overall picture of not just the inefficiencies but also the aspects where the NAS has performed well in a given situation from which specific information about the effects of a policy change on the NAS performance at each level can be determined. These metrics are further validated with real traffic data using the Future Air Traffic Management Concepts Evaluation Tool (FACET) for three en-route sectors and an Air Route Traffic Control Center (ARTCC). ^ Further, this work proposes a framework to compute the minimum makespan and the capacity of a runway system in any configuration. Towards this, an algorithm for optimal arrival and departure flight sequencing is proposed. The proposed algorithm is based on a branch-and-bound technique and allows for the efficient computation of the best runway assignment and sequencing of arrival and departure operations that minimize the makespan at a given airport. The lower and upper bounds of the cost of each branch for the best first search in the branch-and-bound algorithm are computed based on the minimum separation standards between arrival and departure operations set by the Federal Aviation Administration. The optimal objective value is mathematically proved to lie between these bounds and the algorithm uses these bounds to efficiently find promising branches and discard all others and terminate with atleast one sequence with the minimal makespan. The proposed algorithm is analyzed and validated through real traffic operations data at the Hartsfield-Jackson Atlanta international airport.^

]]> Chandrasekar Sureshkumar Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI1535167 http://docs.lib.purdue.edu/dissertations/AAI1535167 Wed, 22 May 2013 15:46:06 PDT Users, Engineers, Surveyors, and GIS Professionals spend an enormous amount of time correcting field surveys to the classical State Plane Coordinate System (SPCS). The current mapping corrections are in the order of 1:30,000, or 33 parts per million (ppm). Modern surveys (e.g., GPS/InCORS) have an accuracy of a few parts per million. Whenever original surveys made on the surface of the Earth need to be reduced to a mapping reference surface, surveyed distances and angles (azimuths) need to be corrected. Measured distances need to be corrected for two scale factors: 1) due to the mapping scale inherent in conformal mappings, and 2) due to terrain heights. Measured angles (azimuths) need to be corrected for so-called convergence angles. The application of these necessary corrections is time consuming and may add an estimated 15 to 20% to the cost of a survey. The omission of these corrections corrupts the reliability of survey results. A new Indiana Coordinate Reference System (INCRS) allows for so much smaller corrections that when omitted the errors committed are small, and may be even neglected for surveys less accurate than a few ppm. In a few areas of Indiana (e.g. Clark County), terrain heights corrections are still needed because these corrections due to the terrain roughness are at the 14 ppm level. The proposed INCRS not only reduces the scale factor from 30 ppm to a few ppm, but also the convergence angles are reduced by a factor of four (from about 0.5 degree to about 7–8 arcminutes).The new much more accurate mapping system has been developed based on closed formula expressions and simple mathematical coordinate transformations.^

]]> Chisaphat Supunyachotsakul Geodesy|Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI1535165 http://docs.lib.purdue.edu/dissertations/AAI1535165 Wed, 22 May 2013 15:46:05 PDT When considering the durability of a bridge, the concrete deck is often the most vulnerable component and can be the limiting factor affecting service life. To enhance the durability of both new and existing bridge decks a protective system is often provided to prevent or delay the ingress of chlorides and moisture to the reinforcing steel. In the state of Indiana this protective system typically comes in the form of a concrete overlay or a thin polymer overlay. Another protective system widely used in the United States and in many countries internationally consists of a waterproofing membrane overlaid with asphaltic concrete. Due to a history of poor performance in the 1970's and the 1980's a moratorium has been placed on the installation of waterproofing membranes in Indiana. ^ This study reevaluates the state-of-the-practice of bridge deck protection in Indiana with the goal of enhancing the Indiana Department of Transportation's toolbox of bridge deck protective systems. Much consideration was given to the state-of-the-art and state-of-the-practice in bridge deck protective systems used by other state transportation agencies as well as by international transportation agencies. Focus was placed primarily on the practice of installing waterproofing membranes and the latest technologies being used. Based on the information gathered, various protective systems were evaluated and guidance was provided on the selection of the most appropriate systems. Guidance was also provided regarding the best practices used to install and maintain these various systems. ^

]]> Brad Strandquist Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI1535166 http://docs.lib.purdue.edu/dissertations/AAI1535166 Wed, 22 May 2013 15:46:05 PDT This work explores a possible solution to an observed mismatch between a verb-centered syntactic analysis paradigm and noun-centered information sources. The latter may form not only the larger information stores online, access to which is improved by progress in natural language understanding systems but may also extend to most texts in general. Some basic categorization of texts along these lines provides testing classes by which to evaluate the performance of a noun-driven syntax representation. A syntax parser was developed and instrumented to provide analysis. The noun-driven representation matches or outperforms more traditional representations; results are discussed in conjunction with findings about the parser's performance and the adequacy of the text categories.^

]]> Lauren M Stuart Language, Linguistics|Information Science|Computer Science http://docs.lib.purdue.edu/dissertations/AAI1535164 http://docs.lib.purdue.edu/dissertations/AAI1535164 Wed, 22 May 2013 15:46:04 PDT As a consequence of the successful harnessing of solar radiation pressure demonstrated by JAXA's IKAROS mission, the interest and developments in the field of solar sails has gained a significant momentum. Sail-based spacecraft potentially offer indefinite maneuvering capability by exploiting photons from the Sun as a means of propulsion. Incorporating a solar sail model within the context of the circular restricted three-body problem extends trajectory design options. In the last few decades, the Lagrangian points, L _i, as defined in the restricted problem, have increasingly become a focus for scientific spacecraft mission applications. In this investigation, a hybrid model that incorporates a solar sail force into the circular restricted three-body problem (SS-CR3BP) is developed. As a result of the additional force, the displaced locations of artificial collinear Lagrangian points are determined and exploited for trajectory design. In fact, various trajectories are constructed that employ only sail orientation angles to move through this dynamical regime. In particular, periodic orbits are computed in the vicinity of the displaced artificial L₁ equilibrium point, located between the Sun and the Earth in this Sun-planet system. A sample offset periodic orbit is demonstrated that hovers over the displaced L₁ point. Trajectory modifications are performed in the vicinity of the L₁ equilibrium point using solar sail angles. Three-dimensional transfers between halos at three different sizes is also constructed to exhibit the capabilities of solar sails based on specific mission objectives. Thus, in this investigation, solar sail capabilities that widen the design space for mission design in the restricted three-body problem are explored.^

]]> Rohan Sood Engineering, Aerospace|Physics, Astrophysics http://docs.lib.purdue.edu/dissertations/AAI1535163 http://docs.lib.purdue.edu/dissertations/AAI1535163 Wed, 22 May 2013 15:46:03 PDT According to the 2008 ILRI report, ASALs comprise more than 40% of the earth's land surface and supports 20% of the total human population. The report also discussed that two thirds of Africa is classified as deserts or dry lands and these are concentrated in the Sahelian region, the Horn of Africa and the Kalahari in the south. As per the UN Economic and Social report of 2007, Africa is especially susceptible to land degradation and bears the greatest impact of drought and desertification. The 2011 drought in Horn of Africa was considered to be the worst in past 60 years which affected 13.5 million people in these regions (IFRC 2011). Disaster events like droughts have far reaching adverse impacts on human health, food security, economic activity, physical infrastructure, natural resources and the environment, and national and global security (Diene et. al. 2007). Although drought has several definitions, the central element in these definitions is water deficit. Water interventions by Government and NGOs in ASALs of Africa are short term relief programs and do not accommodate the long term water needs of the community. ^ A holistic framework for capacity building is proposed in this research to achieve sustainable water management system in ASALs of Africa. A sustainable water management system in this research is a combination of an indigenous water management practice in ASALs of Africa and planned strategies for using the water efficiently for long term. A matrix is proposed in this research which highlights different capacity types along with the three levels of capacity. The columns mention the capacity types which are social, economic, and environmental whereas the levels of capacity i.e. individual, organizational level and system level are represented in rows. Capacity building is a five phase cyclic process which involves preparation, analysis planning, implementation and evaluation. The first four phases use the above proposed matrix to demonstrate the stages of capacity building at three levels and three different types. The final phase evaluates the impact of the overall capacity building process using a system dynamics model. This model helps in projecting the water availability in a region, and the social, economic and environmental impact of the sustainable water management system.^

]]> Akanksha Sinha African Studies|Engineering, Civil|Water Resource Management http://docs.lib.purdue.edu/dissertations/AAI1535161 http://docs.lib.purdue.edu/dissertations/AAI1535161 Wed, 22 May 2013 15:46:02 PDT Fuel injection systems have become the primary fuel delivery systems in internal combustion engines. For better combustion performance, modern fuel injection systems require flexible fuel injection with complex injection rate profiles. Piezoelectric actuator-based injectors are capable of delivering a wide range of injection profiles including tightly-spaced multiple pulse profiles as well as continuously variable injection profiles, which is known as "rate shaping". The challenge of precisely controlling the fuel flow rate of an injector comes from its highly dynamic internal system. A further difficulty is out of the absence of a means to measure the fuel flow rate from the injector while on the engine, for use in diagnostic flow control algorithms. Therefore, closed-loop control with on-line estimation of the fuel flow rate turns out to be a solution. ^ This thesis summarizes an effort resulting in within-a-cycle estimation of injected fuel for "rate shaped" profiles. First a physically-based simulation model is introduced, which describes injector dynamics in detail. The derivation of the dynamic equations is illustrated briefly. Next, a reduced order model is introduced by simplifying the simulation model. The reduced order model captures the main components of the injector. Furthermore, from the reduced order model, an estimation algorithm is derived and implemented at a "loop time" of 6 µs on an FPGA based system with line pressure measurement as feedback. The resulting estimator is experimentally validated, and it is able to make an on-line prediction. The prediction error of the fueling amount per cycle is less than 10%. In summary, the work mainly focuses on the development of a physically-based, experimentally-validated estimator, for the purpose of designing a controller which provides ways to reduce the overall fuel consumption and harmful emissions of diesel engines.^

]]> Jin Shen Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1535162 http://docs.lib.purdue.edu/dissertations/AAI1535162 Wed, 22 May 2013 15:46:02 PDT Past research has demonstrated that lower commitment to a relationship is associated with higher probability of dissolution (Le & Agnew, 2003). Not surprisingly, then, is the fact that past research has not focused on those who may violate this pattern: those who are high in commitment to their partner yet initiate a breakup. The current research combines considerations from both interdependence and attachment perspectives in understanding conditions that may give rise to exceptions to the “high commitment–low breakup probability” rule. Interdependence research has shown that differing levels of commitment is a vulnerable state and may instigate corrective action. Attachment research has shown that anxiously attached individuals are hyper-vigilant for relationship threatening cues and worry that their partner is not as committed. Consistent with hypotheses, results from longitudinal data obtained from 113 dissolution initiators found that highly committed individuals who feel more committed than they perceive their partner to be have greater attachment anxiety at Time 1, and are more likely to initiate breakup by Time 2, than are those who are less committed than they perceive their partner to be and/or lower in commitment at Time 1. Implications of these results are discussed.^

]]> Emily E Short Psychology, Social http://docs.lib.purdue.edu/dissertations/AAI1535160 http://docs.lib.purdue.edu/dissertations/AAI1535160 Wed, 22 May 2013 15:46:01 PDT This research study aims to find the relationship between the scores for the Purdue Spatial Visualization test (PSVT) and the Wonderlic Personnel test (WPT) for American collegiate football players. Fifty-five collegiate football players took part in the study by attempting the PSVT and the WPT. The scores on these tests were compared to find if there existed a correlation between the scores on both these tests. The results showed that the scores on both these tests had a significant correlation with respect to each other. But, the group that took the WPT before the PSVT showed a lower correlation between the scores. It was also observed that the age of the participants had a low/negative correlation to the scores on both the PSVT and the WPT, which can be a important topic of future research. The study proposes a more dynamic visualization measurement, which will be able to help scouts and coaches predict performance of athletes over a period of time.^

]]> Karthik Sukumar Psychology, Cognitive http://docs.lib.purdue.edu/dissertations/AAI1535144 http://docs.lib.purdue.edu/dissertations/AAI1535144 Wed, 22 May 2013 15:46:00 PDT Torque tests, which are performed immediately after a standard penetration test (SPT), have grown in popularity since its conception in Brazil during the early 1990s. Purdue University developed the first automated torqueing hardware in 2010. SPT, SPT-Torque and cone penetration test (CPT) field testing were performed in glacial till soil at four different sites in northern Indiana and one site in southern Indiana. Index tests were performed for the soil samples collected at each of these sites. Relationships between the torque ratio (the measured torque divided by the corrected SPT blow count) and unit side resistance versus normalized SPT blow count (N_1,60) and normalized CPT cone resistance (q_c,1) were explored for these soils with the unit side resistance versus the estimated undrained shear strength was explored for saturated clay soils. Reliable correlations based on the torque ratio were not achieved based on the data collected for the different soils tested. However, high coefficients of determination were obtained for the normalized equations developed for clayey soils and saturated non-plastic silt. Relatively low coefficients of determination were obtained for saturated and unsaturated sandy soils. The low coefficients of determination values are attributed to the small population dataset for sandy soils and the difficulty of adequately determining the degree of saturation for unsaturated non-plastic soil types due to the soil structure destruction with sampling. Overall, it was found that the relationships are strong for clay and saturated non-plastic silt and it is recommended that further data be collected to continue to strengthen all relationships, especially for sand and unsaturated non-plastic silt.^

]]> Seth Daniel Scheilz Geotechnology http://docs.lib.purdue.edu/dissertations/AAI1535142 http://docs.lib.purdue.edu/dissertations/AAI1535142 Wed, 22 May 2013 15:45:59 PDT Due to the vulnerability to hurricanes in the United States and its territories, comprehensive evacuation plans and strategies need to integrate transportation theory with evacuation behavior from a household level. Public agencies and emergency officials need to understand different dimensions of the overall evacuation process in order to mitigate devastating impacts of frequently occurring hurricanes. Route choice during evacuation is a complex process, because evacuees may prefer to take the usual or familiar route on the way to the destination or they might follow the routes recommended by the emergency officials. Depending on the condition of the traffic stream, sometimes they might switch to a different route to obtain better travel time from the one initially attempted. In this thesis, we explain a modeling approach which offers better understanding of the routing strategies taken by the evacuees to reach a safe destination during hurricane evacuation. By using data from Hurricane Ivan, a mixed (random parameters) logit model is estimated which captures the decision making process on what type of route to select while accounting for the existence of unobserved heterogeneity across households. In addition, an ordered probit model with random parameters has been developed to capture the underlying unobserved characteristics in the timing behavior of the evacuees that elapses in between their evacuation decision and actual evacuation. Estimation findings indicate that the choices of evacuation routing strategy and the timing behavior involve a complex interaction of variables related to household location, evacuation characteristics, socio-economic characteristics and some other important characteristics. The findings of this research are useful to determine different fractions of people in selecting a type of route and evacuees evacuating early or delaying for some time for a given socio-demographic profile once they actually decide to evacuate during a hurricane evacuation.^

]]> Arif Mohaimin Sadri Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI1535143 http://docs.lib.purdue.edu/dissertations/AAI1535143 Wed, 22 May 2013 15:45:59 PDT A method to choose controller gains for a PID controller to produce a fast response with no overshoot for step set point changes was developed for a First Order Lag plus Integrator System. By choosing controller gains such that the output remains saturated during most of the set point change, an approximately time-optimal response could be achieved. To tune the controller, a fixed value for the proportional gain was chosen to achieve saturation and a fixed value for the integral gain was chosen to eliminate steady-state errors due to disturbances. Using a simulation of the closed-loop system, a single-dimensional search algorithm to determine an optimal value of the derivative gain was used to generate a set of data relating this optimal gain to the time constant, plant gain, and set point system parameters. Using symbolic regression, a function to generate Kd based on these parameters was obtained. Simulation results showed that this tuning method resulted in the generation of a bang-bang type control actions, resulting in fast settling times and no overshoot while maintaining reasonable disturbance rejection. Similar results were obtained when the controller was implemented on a microcontroller controlling a DC motor.^

]]> Noah Salzman Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1535141 http://docs.lib.purdue.edu/dissertations/AAI1535141 Wed, 22 May 2013 15:45:58 PDT The current study seeks to investigate the effects of the progression of Parkinson's disease (PD) on respiratory support for speech during an extemporaneous speech task using a longitudinal design. Eight individuals with PD, four females and four males, and eight age and sex-matched controls (OC) spoke extemporaneously about a topic of their choice for approximately two minutes. Data were collected at two waves of time, Wave 1 and Wave 2, separated by 3.63 years on average. Lung volume initiations (LVI), lung volume terminations (LVT), lung volume excursions (LVE), % vital capacity (%VC) expended per syllable, number of syllables produced per second, and syllables per breath group were measured. Individuals with PD had lower LVI, LVT, and smaller LVE from Wave 1 to Wave 2 while the OC showed no changes in LVI, a decrease in LVT, and a larger LVE from Wave 1 to Wave 2. Individuals with PD had no changes in SPL and %VC per syllable, an increased rate of speech, and shorter utterances from Wave 1 to Wave 2. The OC showed an increase in SPL and %VC per syllable, no changes in speech rate, and shorter utterance lengths from Wave 1 to Wave 2 waves. It is clear from these data that typical aging and PD result in very different changes to respiratory support for speech. In individuals with PD, the lower LVI and LVT suggest that the progression of the disease is linked with changes to respiratory physiology, which may be as a result of increased rigidity in the respiratory system. The changes in lung volumes, including a decrease in LVE, likely resulted in a decrease in utterance length for individuals with PD. The increase in LVE with shorter utterances was likely due to the increase in %VC per syllable for the OC.^

]]> Zeina Marie Saba Health Sciences, Speech Pathology http://docs.lib.purdue.edu/dissertations/AAI1535140 http://docs.lib.purdue.edu/dissertations/AAI1535140 Wed, 22 May 2013 15:45:57 PDT Buildings are major consumers of energy and are responsible for about 40% of total carbon emissions. Therefore there is large scope to reduce the impact buildings have on the environment through energy efficiency measures. Governments have been taking steps towards achieving more efficient buildings by implementing stricter energy use limits on buildings over the last number of years. Since there is no uniform building energy code how can different countries buildings establish how they are performing in relation to each other? ^ Approximately 80% of the current building stock will still exist in 50 years' time therefore greater attention needs to be paid to the energy standards that are applied to building retrofit projects, in order to ensure that the buildings of the future don't have the same impact on the environment as existing buildings. ^ This document presents the details of a study conducted to determine how American building energy standards compare to EU led Irish building regulations. ^ ^

]]> Miriam Ryan Energy http://docs.lib.purdue.edu/dissertations/AAI1535139 http://docs.lib.purdue.edu/dissertations/AAI1535139 Wed, 22 May 2013 15:45:56 PDT Water comprises 99% of most spray solutions and properties of the water used as carrier can influence the efficacy of herbicides. Water pH is one property of water which can limit the solubility of some herbicides or cause degradation of herbicides through hydrolysis. Water hardness, or the amount of dissolved cations in water, can reduce herbicide efficacy due to binding of herbicide molecules to cations. The presence of these cations can cause reduced absorption or translocation of the herbicide into plants. Glyphosate is the most studied herbicide with respect to the influence of water pH and hardness. Some herbicides have also exhibited reduced efficacy when co-applied with other herbicides or foliar fertilizers. Antagonism of herbicides has been documented with protoporphyrinogen IX inhibiting herbicides and glyphosate. Glyphosate has been documented to exhibit reduced phytotoxicity when applied with manganese fertilizer. The objective of this research was to evaluate the response of selected herbicides applied in water with varying pH and hardness, or co-applied with various herbicides and foliar fertilizers. ^ Saflufenacil, a protoporphyrinogen IX inhibitor, was tested to determine a response to five pH levels (4.0, 5.2, 6.5, 7.7, and 9.0) or three water hardness levels (0, 310, and 620 mg L^-1). A field study on common lambsquarters and giant ragweed was conducted as well as a greenhouse bioassay on horseweed and corn to determine the influence of these water properties on saflufenacil efficacy. In both the field and greenhouse experiments, no influence of water hardness was seen when proper adjuvants were included in the spray solution. However, water pH at 4.0 reduced the efficacy of saflufenacil on common lambsquarters in the field experiments and corn in the greenhouse experiments. High pressure liquid chromatography testing on the solubility of saflufenacil found that the solubility of saflufenacil was reduced from 3,687 mg L^-1 at pH 7.7 to 10 mg L^-1 at pH 4.0. This reduction in solubility may have led to the reduced efficacy on corn in the greenhouse where a pH of 4.0 showed only 79% reduction in growth as compared to 87% reduction in growth with a pH of 7.7. ^ A second study on saflufenacil was conducted to test if adjusting the pH of the saflufenacil solution would influence efficacy. Saflufenacil was mixed in five different carrier waters with initial pH values of 4.0, 5.2, 6.5, 7.7, or 9.0 and adjusted to one of four final pH levels (4.0, 6.5, 9.0, or no change). When initial pH levels were acidic (4.0 or 5.2) and raised to a more neutral pH, saflufenacil efficacy on corn was increased. It was also observed that when initial pH was 6.5 or 7.7 and reduced to 4.0, saflufenacil efficacy on corn was reduced. ^ Saflufenacil was also tested for interaction with fourteen herbicides. A field study was conducted on fallow ground containing common lambsquarters, giant ragweed, and giant foxtail. Saflufenacil co-applied with glyphosate or glufosinate provided the most consistent and best control of giant foxtail and common lambsquarters at 14 days after treatment. At 21 days after treatment, control of common lambsquarters was best with 2,4-D and dicamba mixed with saflufenacil. All tank mixtures provided 85% or more control of common lambsquarters except imazaquin, imazethapyr, or chlorimuron-methyl co-applied with saflufenacil. All tank mixtures provided better control of weeds as compared to saflufenacil alone. ^ 2,4-D and dicamba, two growth regulator herbicides, were tested for a reduction in efficacy when applied in water with calcium ions, magnesium ions, manganese fertilizer, or zinc fertilizer. 2,4-D control of horseweed or redroot pigweed was decreased when ammonium sulfate was not included in the spray solution regardless of the presence of cations or fertilizers. Overall, 2,4-D efficacy was reduced when applied in water containing manganese fertilizer as compared to 2,4-D applied in deionized water. The presence of calcium ions decreased 2,4-D control of common lambsquarters when ammonium sulfate was not used. Dicamba control of common lambsquarters and redroot pigweed was decreased when applied in water with magnesium or manganese in the absence of ammonium sulfate. No reduction in dicamba control of horseweed was noted across cation solutions, as was seen with 2,4-D.^

]]> Jared M Roskamp Agriculture, General|Agriculture, Plant Culture http://docs.lib.purdue.edu/dissertations/AAI1535138 http://docs.lib.purdue.edu/dissertations/AAI1535138 Wed, 22 May 2013 15:45:55 PDT The design, construction, and testing of a unique 2.6 gram electromagnetic actuator operated at resonance with the specific application to flapping flight is presented. An initial performance evaluation of a commercially available electromagnetic actuator used for static positioning of control surfaces on toy helicopters paired with a fabricated flapping wing was performed. An alternative wedge shaped electromagnetic actuator fitted with "virtual" spring magnets was proposed to address the performance issues associated with the commercial actuator. The unique wedge shape of the proposed actuator allows for a maximum stroke amplitude of 120°. without interface through contact by the wing with the sides of the coil. Additional disc magnets attached to the perimeter of the electromagnetic coil were proposed to increase the systems stiffness, adding an energy storage component to the system and creating a "virtual" spring like effect without the additional of direct mechanical coupling. By selecting the size and quantity of these spring magnets, increases to the stiffness of the system could be manually adjusted increasing the bandwidth of the actuator and allowing for system resonance to be achieved. With the application of a potential difference of alternating polarity across the coil, a driving torque is created by the electromagnetic coil and an opposing counter torque is generated by the displacement of the rotor due to the spring magnets. System resonance could then be achieved by tuning the frequency of the external voltage supply to match that of the primary mode of resonance for the system, resulting in peak amplitudes in the wings stroke dynamics. ^ An analytical model of the system's two degree of freedom dynamics was then derived using a rigid body dynamics, simplified electromagnet relationships based on Maxwells equations, and accepted aerodynamic models for translation and rotational damping of flapping wings. A numerical simulation was then preformed based on these models and used to evaluate the response of the system at multiple voltage frequencies and to gauge the dependency of the coupled system dynamics. A step like response was observed to occur at low voltage frequencies with a steady transition to harmonic motion at higher frequencies near resonance. Simulating a simplified from of the dynamics model, assuming only a single degree of freedom, weak coupling of the systems dynamics near resonance was found by direct comparison of simulated response with the majority of the two degree of freedom model's trajectory and amplitude matching that of simplified model. Independent bench tests preformed on the coil and spring magnets were then used to measure the torque generated for comparison to their derived models. Based on deviation in trends found from this comparison, modifications to the analytical models of the actuator were made to more accurately represent the measured data. Using the simplified model of that actuator dynamics, with modified expressions for the torque generated by the coil and spring magnets, perturbation theory was applied to determine an approximate solution for the maximum stroke of the system operating near resonance finding the amplitude of the stroke dynamics independent of the nonlinear stiffness term. ^ A set of 16 test wings were fabricated for use with the electromagnetic actuator during experimentation. Wing parameters used in to construct these test wings were varied systematically to generate unique wing profiles within the range of parameters of actual biological data. Post fabrication, wing shape parameters were determined using imaging processing software to analyze digital pictures taken of the wings. Compound pendulum experiments then were preformed with the test wing suspended from a fabricated test fixture to determine their period of oscillation resulting from a small perturbation applied to the leading edge. Each test wings center of mass was determined from the intersection of a line along the wing's principle axis and the a reference line defined by balancing the wing on a knife edge. Based on the results of these experiments the moment of inertial for each wing was ascertained and tabulated. ^ Frequency response experiments were conducted on the electromagnetic actuator and wing pair using the entire set of test wings by varying supply voltages and spring configurations. Both course and fine frequency bands of voltage signals were applied to the coil and the response of the wing recorded using a high speed camera to determine the resonance frequency and the maximum stroke amplitude. The results of these test were then compared to the values obtained from approximates solution finding 4.3% error in frequency and 7.2% in amplitude, validating the use of these expressions. With the resonate frequency determined, wing kinematics and mean lift measurements were made for the two best preforming wings operating at resonance, reporting a lift-to-weight ratio of over one at 24V for one of the test wings. (Abstract shortened by UMI.) ^

]]> Jesse A Roll Engineering, General|Engineering, Mechanical|Biophysics, Biomechanics http://docs.lib.purdue.edu/dissertations/AAI1535136 http://docs.lib.purdue.edu/dissertations/AAI1535136 Wed, 22 May 2013 15:45:54 PDT In very low ambient temperature regions, both heating capacity and coefficient of performance (COP) of traditional air-source vapor compression heat pumps drop significantly with a decrease in outdoor air temperature. The current study investigates two alternative technologies for improving the efficiency of vapor compression cycles especially at very low ambient temperatures. The first method is liquid flooded compression with regeneration in which a significant amount of non-volatile liquid is mixed into the stream of refrigerant vapor entering the compressor in order to approach an isothermal compression process. The second method is multi-port refrigerant injection during compression and economizing which is similar to multi-stage compression in providing refrigerant cooling between compressor stages and a lower refrigerant quality entering the evaporator. ^ Both technology improvements address the thermodynamic inefficiencies that are inherent within the simple vapor compression cycle that is employed in most heat pumping equipment. The benefits of oil flooding and saturated vapor injection are evaluated using experimental testing of an oil flooded R410A scroll compressor and a 2 port saturated vapor injection R410A scroll compressor and simulation. The results show that the performance of the compressor increases with oil flooding and saturated vapor injection especially at very low evaporation temperatures. The experimental compressor results were used for system analysis of liquid flooded compression with regeneration and saturated vapor injection. At -10°C ambient temperature, estimated COP (heating) of the flooded compression with regeneration cycle was 25% higher while that of the vapor injection cycle was 12.5% higher than the standard vapor compression cycle. For Minneapolis, the seasonal efficiency (heating) of a flooded compression with regeneration cycle was estimated to be 34% higher while that of the vapor injection cycle was 21% higher than the standard vapor compression cycle. Both technologies lead to higher energy efficiency and less degradation in heating capacity at low ambient temperatures. Also, a previously developed detailed flooded scroll compressor model has been validated with the oil flooding experimental data, for which good agreement was found. ^

]]> Sugirdhalakshmi Ramaraj Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1535137 http://docs.lib.purdue.edu/dissertations/AAI1535137 Wed, 22 May 2013 15:45:54 PDT Current U.S. design provisions for lap splices of deformed bars in tension were developed primarily from tests conducted on beams with lap lengths not exceeding 40 bar diameters. But the provisions often require splices to be longer than 40 bar diameters. Recent structural failures have indicated the vulnerability of lap splices with length-to-bar-diameter ratios equal to or exceeding 40. In this study, the tensile strength of unconfined deformed-bar lap splices with different lengths is reexamined. The focus is on lap splices with length-to-bar-diameter ratios of 40 or more. The tensile strength of lap splices in configurations resembling those observed to have splice failures in the field is also examined. ^ Three series of tests (with a total of forty-five specimens) were conducted on specimens with lap lengths varying from 20 to 85 bar diameters. In series one, twenty-seven prismatic coupons were tested monotonically to failure in tension. In the second and third series, a total of eighteen beams were tested to failure. The beam lap splices were located in a region of constant moment. ^ The results in this study indicated that increasing the length of a lap splice beyond 45 bar diameters was an inefficient way to increase the strength of the splice. The results also indicated that a mean unit bond strength of 5√f'_c (in psi) is not a lower bound, as suggested by current design provisions, to the strength of unconfined deformed-bar lap splices with a minimum clear cover of 1 bar diameter and a minimum clear spacing between bars of 2 bar diameters. ^ To address these issues, a new perspective on the tensile strength of unconfined lap splices is explored. It is suggested that, rather than setting a lower bound to the mean unit bond strength for design, an upper bound of 900√f'_c (in psi) should be set for the maximum steel stress that can be developed in unconfined deformed-bar lap splices. ^

]]> Brian P Richter Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI1535135 http://docs.lib.purdue.edu/dissertations/AAI1535135 Wed, 22 May 2013 15:45:53 PDT Piezoelectric injectors are capable of delivering a wide range of injection profiles including tightly spaced multiple pulses as well as continuously variable injection called rate shaping. Rate shaping has been recognized as an effective way to reduce the nitrogen oxide (NO_x) emissions without a huge detriment in particulate matter (PM) and fuel consumption. ^ Piezoelectric injectors are highly dynamic systems, requiring careful input modulation to achieve sophisticated flow profiles. Within-a-cycle closed-loop feedback control techniques could prove to be a key enabler for this technology, but will require on-line estimation of the injected fuel flow rate to be realized because of the inability to measure the injector flow rate when used on an actual engine. ^ This thesis describes the development and implementation of a physics-based fuel flow estimator which can be used as feedback to a closed-loop controller. Available measurements on the piezoelectric injector rig are used for dynamic state estimation. The estimator is realized in hardware using a Field Programmable Gate Array (FPGA) to reduce the loop computation time and provide a platform for within-a-cycle controller design. ^ Real-time estimator results are compared against measurement data from the rig for a variety of flow profiles at different toe heights and different operating rail pressures. Estimator results, in general also show notable improvement against pure open-loop simulation results. ^ Also, the thesis summarizes the development of an on-the-fly modifiable input voltage generation technique for the rate shaping injector and a high speed data acquisition system for the sensor signals, implemented using the NI hardware. ^ Overall, this thesis describes a generalizable method to produce estimates of the rate shape injection flow profiles for the purpose of subsequent within-a-cycle controller design. The controller can provide a platform for making substantial improvements in combustion-related efficiency and emissions by increasing the flexibility of the fuel injection system.^

]]> Neha S Ruikar Engineering, Electronics and Electrical|Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1535134 http://docs.lib.purdue.edu/dissertations/AAI1535134 Wed, 22 May 2013 15:45:52 PDT The potential harvest of corn stover as a feedstock for biofuels to meet government mandates has raised concerns about the environmental impacts of its removal from fields. Furthermore, in order to meet these mandates, larger quantities of stover will be required. As a result, increased attention has been placed on sustainable agronomic practices, such as cover crops. While cover crops may offer desirable benefits, adoption comes at a cost. The objective of this study was to determine the extent to which cover crop costs could be compensated by additional stover removal and additional agronomic benefits from the use of cover crops. ^ To meet the objective, we estimated cover crop costs and cover crop agronomic benefits and employ a series of benefit-cost analyses, using stochastic analysis in @RISK. Additionally we tested cover crops with stover removal for 24 Indiana farms in a linear programming model, PC-LP. Cover crop costs ranged from $33.09/acre to $69.81/acre, with variability being driven by differences in the seeding rate and seed cost. Agronomic benefits included reduced erosion, which was calculated using a newly created integrated modeling system. The mean estimated reduced soil erosion with a cover crop and no residue removal was 0.32 tons/acre. A benefit-cost analysis of cover crop agronomic benefits indicated that from a private perspective (on-site) benefits ranged from $37.01/acre to $77.73/acre, and $39.51/acre to $80.24/acre from society's perspective. These benefits were highly influenced by added or scavenged nitrogen (N) from the cover crop; therefore eliminating added N and retesting the on-site case, benefits ranged from $30.24/acre to $54.48/acre. Benefit-cost analyses when considering the agronomic benefits of cover crops resulted in a range of a net loss of $4.49/acre to a net benefit of $35.34/acre for the private perspective, and a net loss of $2.43/acre to a net benefit of $37.85/acre for the societal perspective. Estimating the additional removable stover with a cover crop also utilized the newly created integrated modeling system. Results indicated, that on average, while holding soil erosion constant, an additional 2 tons/acre of stover could be removed. Accounting for cover crop costs and stover removal, a benefit-cost analysis suggested that at a farm-gate stover price of $60/ton, net benefits ranged from a loss of $7.09/acre to a net benefit of $29.63/acre. At a farm-gate stover price of $80/ton, net benefit ranged from $58.53/acre to $95.24/acre. Results from PC-LP indicated that cover crops, along with increased stover removal, impacted crop rotations, increased the total amount of stover harvested, and significantly increased farm profits.^

]]> Michelle R Pratt Economics, Agricultural http://docs.lib.purdue.edu/dissertations/AAI1535133 http://docs.lib.purdue.edu/dissertations/AAI1535133 Wed, 22 May 2013 15:45:51 PDT As global population and subsequent demand on the provisioning services of natural systems continue to rise, it is increasingly important to identify creative, pragmatic solutions to meet these needs while minimizing environmental degradation. Of particular importance are agricultural ecosystems, among the most widespread anthropogenically driven and managed systems. Soil moisture is critical to characterizing many atmospheric, hydrologic, and land-surface interactions relevant to monitoring and modeling such systems. However, soil moisture is spatially and temporally highly variable, and is thus challenging to measure in a meaningful, representative manner with point based in situ sensors. Alternatively, remote sensing in the microwave region of the electromagnetic spectrum is capable of providing all weather, day/night gridded global soil moisture measurements. Unfortunately, the spatial resolution of standard passive microwave based products is too low (∼40 km) for most hydrologic applications (1–10 km). One approach to overcome this limitation is to combine soil moisture maps with fine scale ancillary remote sensing data to downscale soil moisture data products. ^ This research focused on evaluating two variants of a downscaling algorithm applied to soil moisture products derived from data acquired by the SMOS (Soil Moisture and Ocean Salinity) satellite over a sensor network in the Upper Cedar Creek Watershed in northeastern Indiana. Results in this region indicated that while the accuracy of standard SMOS products does not meet the stated mission objectives (0.068 m³/m³ vs. 0.04 m³/m³), the derived downscaled data did not degrade either the root mean square difference or correlation with in situ measurements. Potential deficiencies in the downscaling models were identified and discussed. Overfitting was detected in one approach, and both models were inadequate for tracking temporal variations associated with vegetation data in the Midwest. A qualitative evaluation of within network variability and auxiliary soil moisture data sources was also performed. ^ Comparison of remotely sensed data to ground networks provided insight into sensor derived response over a heterogeneous area and potential to exploit such relationships. By refining downscaling approaches, it should be possible to better resolve the scale at which soil moisture processes act. Specific to agricultural applications, accurate soil moisture estimation can improve yield prediction, forecasting of drought and floods, and water management practices.^

]]> Garett William Pignotti Engineering, Environmental http://docs.lib.purdue.edu/dissertations/AAI1535131 http://docs.lib.purdue.edu/dissertations/AAI1535131 Wed, 22 May 2013 15:45:50 PDT In this project, I present a diachronic analysis of art museums, from the nineteenth century to the present, which investigates the strategies employed by the museum as an agent of cultural change. I do this by developing an ethnography of the museum experience. By looking at chronologically-specific groupings of art museums, traditional structures of the nineteenth century and modern and postmodern structures of the twentieth century, I document the experience that is unique to each architectural strategy. ^ It is my contention that the act of attending an art museum should be seen as one kind of common cultural ritual of the modern world Depending on factors of individual experience like level of education, socio-economic standing, and cultural affiliation, the museum experience is different for each user. By creating a ritualized experience, an art museum reinforces group identity, thereby creating a cohesion that previously did not exist between members of a diverse, often global community.^

]]> Stephanie Lynn Parrish Anthropology, Cultural|Aesthetics|Architecture http://docs.lib.purdue.edu/dissertations/AAI1535132 http://docs.lib.purdue.edu/dissertations/AAI1535132 Wed, 22 May 2013 15:45:50 PDT Documents containing personally identifiable information cannot be shared freely. Text sanitization plays an important role in information dissemination. Current sanitization methods and techniques have focused on finding and hiding personally identifiable information, giving different importance to each. The process of finding personally identifiable information has received more attention by the scientific community than the process of hiding the discovered identifiers. ^ This work presents the use of ontologies as an alternative to efficiently handle the main issues of text sanitization. First we present the ontological framework that supports an information-theoretic approach to reduce sensitivity and identifiability. We then present how the use of properties and axioms from the ontology are used to optimize semantics and utility of text without compromising privacy. Finally, we explain a set of algorithms optimizing semantics with multiple word senses using ontologies and how the result can be used as an alternative to word sense disambiguation as shown by experimental results.^

]]> Pedro J Pastrana-Camacho Computer Science http://docs.lib.purdue.edu/dissertations/AAI1535130 http://docs.lib.purdue.edu/dissertations/AAI1535130 Wed, 22 May 2013 15:45:49 PDT Western bean cutworm (Striacosta albicosta (Smith)) is a relatively new pest in Indiana, being trapped in the state since 2006. In 2009, larval feeding damage in corn reached economically damaging levels in some fields. During this year there was also an outbreak of Gibberella ear rot (Gibberella zeae); corn containing the mycotoxin, deoxynivalenol, produced by this pathogen in concentrations exceeding advised FDA limits caused the grain to be rejected. A three year study was conducted to evaluate the possible affect that western bean cutworm larval feeding damage or presence had on development of Gibberella ear rot in field corn and the role of a pyraclostrobin fungicide (Headline^®) on managing the disease. Caterpillar feeding damage and presence encouraged fungal mycelial growth on field corn ears. An application of the fungicide Headline^® did not reduce nor increase disease symptoms within fields. A management plan that targets the insect pest through appropriately timed insecticide applications also reduces the likelihood of ear rot development within field corn in Indiana. ^

]]> Nicole S Parker Biology, Entomology|Agriculture, General|Agriculture, Plant Pathology http://docs.lib.purdue.edu/dissertations/AAI1535116 http://docs.lib.purdue.edu/dissertations/AAI1535116 Wed, 22 May 2013 15:45:48 PDT The research conducted for this thesis involved investigating the water usage associated with different manufacturing processes. Following preliminary findings a more inventory-oriented methodology was used to account for the water consumption for both direct and indirect usage. Usable water in the form of freshwater is limited; much of the usable water forms a small percentage of what makes up the complete water resource on this planet. The impacts on the environment and the resources that are available are of great concern especially in regions where water is scarce. Water is used both directly and indirectly in manufacturing. One important manufacturing perspective of indirect use of water for manufacturing is related to power consumption. Energy use in the form of electricity drives many manufacturing processes and enables the creation of a variety of products. A mixture of electricity generating technologies provides energy to the power grid, used in the United States. Generally, the power generating technologies that are available and presently used are coal, nuclear, hydro, natural gas, and renewables. ^ The mixture of electricity generating technologies differs from state to state depending what natural resources are available for that particular region. Developing an understanding of the state-to-state mixture differences and the mixture difference effect on the water footprint represented much of the initial research of this thesis. A database was identified that contained the power generation mixture for each state. The power grid and the means of sharing electricity between different states were not considered in this thesis and was beyond the scope of this study. The water energy relationship is still being studied by researchers and much of the impacts of system architectures and energy creation and use on water is still in its beginning stages. Researchers, engineers and manufacturers will be able to control and predict the impacts to our environment much more systematically as policy makers and governments become more supportive in these kinds of efforts. ^ Initially, this research began by investigating the use of energy in machining processes. The machining processes that were chosen were drilling, milling, and turning. The energy required to power such processes was analyzed by using the unit process life cycle inventory (uplci) methodology for frequently used machining materials such as: steel, aluminum, and copper. The power use varies significantly due to the different material properties. For the water footprint in the machining process the results are significant, the Scope 1 definition was strictly for Metal Working Fluids (MWFs) and based on two different allocation methods. Scope 2 water footprint was larger than that of Scope 1 which factored in the power usage and power grid mixture. Quantifying the water and energy use per unit volume was the most practical method to investigate water usage in machining. Similar to a carbon footprint there are three scopes that had to be defined in order to capture the use of water. Water consumption and withdrawals with direct and indirect usage were defined to appropriately allocate water. Scope 1 is direct water usage from Metal Working Fluids (MWFs), Scope 2 is indirect water usage from energy use and Scope 3 all other embodied water usage. ^ A manufacturing facility was chosen to investigate the water use for a six-month period. The facility's main manufacturing process was a stamping operation, for which material flows, and water and electricity consumption were recorded and analyzed. The water usage recorded for parts washing (cleanline) was based on the overall consumption that was experienced for sustaining the facility's production during the six month period. The water footprint for Stamping processes was also found to be very significant, although the use of water for these processes is normally considered to be minimal; however, it was found that the water usage defined in Scope 1 and Scope 2 is substantial. ^ The water footprint will serve as a measure of the water use efficiency and water-energy relationship that exists in a process and to provide more information for industry in identifying areas that can have a potential reduction in the amount of energy and water required to function. This research provides a standard for identifying and quantifying water for direct manufacturing use and indirect water consumption for energy usage in production.^

]]> Jonathan Ogaldez Engineering, Industrial|Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1535115 http://docs.lib.purdue.edu/dissertations/AAI1535115 Wed, 22 May 2013 15:45:47 PDT This study explored the effect of pictorial freehand sketches on CAD model building for first and second year engineering students. Thirty one students from CGT 163 Graphical Communication and Spatial Analysis course at Purdue University completed the study. Subjects were divided into two groups, one of which was required to use pictorial freehand sketches in the visualization process while the other one was not. Subjects were provided real models of physical objects of different complexity and were asked to model a part that would fit in the original one to form a rectangular prism. Outcomes were then analyzed in terms of time spent on the task, number of steps used during the process, and accuracy of the resulting model. In addition, subjects' scores from the Purdue Spatial Visualization Test (PSVT) were recorded and used in the study as a measure of visual ability. The results showed no statistically significant effect of sketching on the construction of CAD models. At this point, we are not ready to conclude that pictorial freehand sketching directly affects CAD model construction. Subjects' visual abilities, on the other hand, had a significant effect on model building.^

]]> Maria D Nizovtseva Engineering, General|Education, Vocational http://docs.lib.purdue.edu/dissertations/AAI1535113 http://docs.lib.purdue.edu/dissertations/AAI1535113 Wed, 22 May 2013 15:45:46 PDT The purpose of this thesis was to develop a mass spectrometric method that allows identification of compounds containing the 3-phenylallyl alcohol in lignin degradation product mixtures because most lignin degradation products with these structural features undergo fragmentation when they are ionized in mass spectrometers by using common methods. The specific goal was to develop a mass spectrometric evaporization/ionization method that produces only one ion type per analyte without fragmentation that can be used to derive MW information The results demonstrate that when sample solutions of lignin model compounds containing the 3-phenylallyl alcohol moiety are ionized by atmospheric pressure chemical ionization (APCI) doped with PdCl₂, they produce abundant (M-H)⁺ ion. The specificity of the method was explored by analyzing various other model compounds which do not contain the 3-phenylallyl alcohol moiety. The model compounds that contained unsaturation in the side chain but no 3-phenylallyl alcohol moiety generated ions such as (M-H+H₂O) ⁺ and (M-H+CH₃OH)⁺ upon APCI after treating the sample with PdCl₂. This may have involved initial formation of (M-H)+ ions which may have rapidly reacted with water or methanol in solution. Model compounds which did not contain unsaturation in the side chain did not generate (M-H)⁺ ion. Experiments performed using (E)-2-methyl-4-phenylbut-3-en-2-ol suggested that the possible site of hydride loss in the formation of (M-H)⁺ ions is the allylic position. Sample solutions of the model compounds containing unsaturation in the alkyl chain developed significant yellowish green color upon treatment with PdCl ₂. The formation of colored solutions suggests complexation between PdCl₂ and the carbon-carbon double bond. The development of color was not observed in case of sample solutions which did not contain unsaturation in the alkyl chain. ^ Finally, the method was used to explore the presence of 3-phenylallyl alcohol moiety containing compounds in real degraded lignin samples. The mass spectra collected before and after treatment of the degraded lignin sample with PdCl₂ indicated the absence of compounds with the 3-phenylallyl alcohol moiety. In order to confirm this conclusion, the degraded lignin samples were doped with known amounts of model compounds containing the 3-phenylallyl alcohol moiety and the mass spectra were measured before and after treating the sample with PdCl₂. The model compounds were easily identified by using this method. This method will greatly facilitate the characterization of mixtures derived from biomass. All experiments were conducted in Thermo Scientific linear quadrupole ion trap (LQIT).^

]]> Padmaja Narra Chemistry, Analytical http://docs.lib.purdue.edu/dissertations/AAI1535114 http://docs.lib.purdue.edu/dissertations/AAI1535114 Wed, 22 May 2013 15:45:46 PDT The smart grid is the future of the power grid. Smart meters and the associated network play a major role in the distributed system of the smart grid. Advance Metering Infrastructure (AMI) can enhance the reliability of the grid, generate efficient energy management opportunities and many innovations around the future smart grid. These innovations involve intense research not only on the AMI network itself but as also on the influence an AMI network can have upon the rest of the power grid. This research describes a smart meter testbed with hardware in loop that can facilitate future research in an AMI network. The smart meters in the testbed were developed such that their functionality can be customized to simulate any given scenario such as integrating new hardware components into a smart meter or developing new encryption algorithms in firmware. These smart meters were integrated into the power system simulator to simulate the power flow variation in the power grid on different AMI activities. Each smart meter in the network also provides a communication interface to the home area network. This research delivers a testbed for emulating the AMI activities and monitoring their effect on the smart grid.^

]]> Uditha Sudheera Navaratne Engineering, Electronics and Electrical|Energy http://docs.lib.purdue.edu/dissertations/AAI1535112 http://docs.lib.purdue.edu/dissertations/AAI1535112 Wed, 22 May 2013 15:45:45 PDT This thesis is composed of two essays that use different methodological techniques to determine the level of technical efficiency for sample tilapia fish farmers in Kenya. The studies also identify farm specific and socio-economic factors that are correlated with the technical efficiency. The first essay uses stochastic frontier analysis (SFA) to assess the level and determinants of technical efficiency for a sample of tilapia fish farmers in Kenya in one stage-procedure. Tilapia fish production data and other relevant information in the Aquaculture Collaborative Research Support Program (ACRSP) program survey, 2011 are analyzed by first estimating the Translog production function before settling on the Cobb Douglas production function involving a model for technical inefficiency effects. The production frontier involves four input variables, including seed, feed, labor and land. The technical inefficiency model includes seven operational and farm-specific variables, namely geography (farm location at County and Regional levels), specialized training by ACRSP, number of trainings, household income, age and education of the household head. ^ The mean technical efficiency for the sample of tilapia fish farmers, estimated by the stochastic production frontier, is low, at 47%. Seed and Land size coefficients in the SFA are estimated to be positive and significant. The results from the technical inefficiency model show that households that have been trained by ACRSP and those with high-income levels have higher levels of technical efficiency than those that have not been trained by ACRSP and those with low incomes respectively. An aged household head dummy variable shows a negative and significant impact on technical efficiency. The implications of these results are discussed. ^ The second essay applies output-based DEA, a nonparametric efficiency measurement technique, to derive technical efficiency measures of sample fish farmers in Kenya. The study also identified farm specific and socio-economic factors associated with technical efficiency using Analysis of Variance (ANOVA), Ordinary Least Squares (OLS) and two-limit Tobit (2LT) models in the second stage analysis. ^ The output production structure for fish farmers is defined in terms of tilapia output. The six input categories used were: seed from government sources, seed from private sources, high quality feed, low quality feed, labor, and pond size. ^ The mean technical efficiency score for the sample fish farms was estimated to be 0.55. Of 118 farms included in the analysis, 41 (or 35%) were technically efficient. Given that the country's current aquaculture production stands at roughly 8,000MT these results imply that there is the potential to increase production by more than 6,000MT (or 44%) through improved efficiency. Spatial location and specialized training of best management practice are found to correlate with fish farmers' efficiency levels. Pond size and socio-economic variables are found to have no correlation with efficiency levels. ^ Key Words: ANOVA; Aquaculture; Cobb-Douglas; DEA; OLS; Developing Countries; Kenya; Non-parametric; Parametric; Technical efficiency; Tilapia; Tobit; Translog; SFA.^

]]> Philip Mutuma Munyua Economics, Agricultural http://docs.lib.purdue.edu/dissertations/AAI1535111 http://docs.lib.purdue.edu/dissertations/AAI1535111 Wed, 22 May 2013 15:45:44 PDT The physicochemical properties of the FPH were examined to characterize their functionality. FPH were produced by 30, 60, 90, 120, and 240 min hydrolysis with Protamex^®, a commercially-available enzyme system. Degree of hydrolysis (DH) data showed substantial cleavage occurring during the reaction, especially in FPH from 120 (∼18% DH) and 240 min (∼53% DH). Mass distribution analysis using sodium-dodecyl sulfate (SDS-PAGE) electrophoresis and mass spectrometry revealed a relatively narrow molecular weight range for FPH-90 and 240 primarily less than 4 kDa, with larger peaks of 11 kDa (FPH-90) and 6.3 kDa (FPH-240) observed, respectively, suggesting a presumably high charge density of the FPH. Amino acid analysis demonstrated that FPH 90 and 240 retained all essential amino acids, including lysine at 10% total amino acid quantity. Desirable polar amino acids, including Asp and Glu, were observed to be in appreciable amount (∼10%) according to total amino acid analysis, whereas freed nonpolar amino acids Val, Met, Ile, Leu, and Phe increased across both treatments (which are known to promote F/T denaturation), but were notably higher in FPH-240. Surface hydrophobicity analysis suggested that FPH from silver carp may have evolving amphiphilic tendencies as the extent of hydrolysis increases; FPH-120 and 240 were noted to have the highest hydrophobicity values (P < 0.05) compared to all other FPH and the non-hydrolyzed (control) carp protein. Sulfhydryl resides were significantly lower (P < 0.05) for all FPH than the control, and this was correlated with near equal increases in disulfide linkages. The physicochemical properties of FPH from silver carp seem to imply a shifting balance in hydrophilicity vs. hydrophobicity as per the hydrolysis conditions. Thus, limited hydrolysis (i.e. up to 90 min) may promote beneficial water-binding of the FPH, while extensive hydrolysis seems to promote derogatory protein-protein interactions. ^ Mince formulations consisted of 6% FPH (w/w) from each hydrolysis time condition, an untreated mince (CTRL), and 8% (w/w) 1:1 sucrose-sorbitol (SUSO), respectively. Mince formulations were evaluated before (Day 0/"D0") and after 6 freeze-thaw cycles (Day 7/"D7") for salt-extractable protein (SEP) content, expressible moisture (EM), antifreeze activity (AF) by differential scanning calorimetry, surface hydrophobicity, and quantities of sulfhydryl residues (SH) vs. disulfide linkages (SS). All FPH-treated mince samples were found to improve SEP recovery, while 240 min retained a significantly higher proportion (P < 0.05) of SEP at Day 7 compared to SUSO. At D7, all FPH treatments had significantly (P < 0.05) lower EM than both the control and SUSO formulations, indicating strong water holding capacity by the FPH. AF activity dropped in the control sample after freeze-thawing, from 20.3% to 5.5% unfrozen water, while the SuSo maintained AF activity at 20.4% (D7). Furthermore, all FPH imparted AF activity equal to or better than SUSO, with the FPH-90 exhibiting significantly higher (P < 0.05) AF activity at Day 7 with 43.9%. Surface hydrophobicity values did not significantly differ on D7 across treatments; however, FPH 30, 60, and 90 each retained a similar hydrophobicity from D0 to D7. FPH 60, 90, 120, and 240 retained total sulhydryl residues better than SUSO, though disulfide analysis returned inconclusive evidence. This evidence suggests that FPH from silver carp using the Protamex^® system may have cryoprotectant capabilities in a frozen fish mince product. ^

]]> Jason Peter Mueller Agriculture, Food Science and Technology http://docs.lib.purdue.edu/dissertations/AAI1535110 http://docs.lib.purdue.edu/dissertations/AAI1535110 Wed, 22 May 2013 15:45:43 PDT The objective of this study was to measure the response of a gas-gas injector to velocity perturbations through CH* emission intensity at a range of instability levels and to provide quality data for comparison with high-fidelity models. To achieve this, an optically accessible, 2-D combustion chamber which self-excites a transverse instability was modified to incorporate a gas-gas shear coaxial injector at the location which coincides with the 1W velocity anti-node in the chamber. By changing the driving injector orientation, different levels of instability were produced, ranging from 8% to 65% of the mean chamber pressure. Filtered high speed video was used to measure CH* chemiluminescence, which was used to provide insight into the coupling processes which drive instability. Several diagnostics were used in the analysis of the CH* video, including the root mean square (RMS) of each pixel over the data interval and the Rayleigh Index. CH* videos synced with pressure and velocity waveform videos provided further insight into the conditions within the chamber and the corresponding injector response, and provided parameters to compare with high-fidelity models. Finally, the relationship between CH* intensity and pressure/velocity perturbations was examined using several methods with the hope of identifying relationships that could be used to develop transfer functions. However, a more thorough investigation of the relationships is needed before this is accomplished.^

]]> Collin J Morgan Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI1535109 http://docs.lib.purdue.edu/dissertations/AAI1535109 Wed, 22 May 2013 15:45:42 PDT This thesis models an airline's decisions about fleet evolution in order to maintain economic and regulatory viability. The aim is to analyze the fleet evolution under different scenarios of environmental policy and technology availability in order to suggest an optimal fleet under each case. An understanding of the effect of aircraft technologies, fleet size and age distribution, and operational procedures on airline performance may improve the quality of policies to achieve environmental goals. Additionally, the effect of decisions about fleet evolution on air travel is assessed as the change in market demand and profits of an abstracted, benevolent monopolist airline. ^ Attention to the environmental impact of aviation has grown, and this has prompted several organizations such as ICAO (and, in response, NASA) to establish emissions reduction targets to reduce aviation's global climate impact. The introduction of new technology, change in operational procedures, etc. are some of the proposed means to achieve these targets. Of these, this thesis studies the efficacy of implementation of environmental policies in form of emissions constraints as a means to achieve these goals and assesses their impact on an airline's fleet evolution and technology use (along with resulting effects on air travel demand). ^ All studies in this thesis are conducted using the Fleet-level Environmental Evaluation Tool (FLEET), a NASA sponsored simulation tool developed at Purdue University. This tool models airline operational decisions via a resource allocation problem and uses a system dynamics type approach to mimic airline economics, their decisions regarding retirement and acquisition of aircraft and evolution of market demand in response to the economic conditions. The development of an aircraft acquisition model for FLEET is a significant contribution of the author. Further, the author conducted a study of various environmental policies using FLEET. ^ Studies introduce constraints on maximum CO₂ emissions that the airline can cause, taxes on airlines for excess emissions, and the use of biofuels. The results obtained indicate that implementation of very strict policies that place a heavy penalty on airlines for environmental inefficiency would lead to a drastic decline in market demand served as well as airline profits. For example, to achieve a 50% reduction of CO₂ emissions by 2050 from the 2005 levels, the airlines would need to leave as much as 45% of predicted market demand unmet, thereby significantly reducing their profits. Taxing airlines for excess emissions would lead them to use large aircraft for short distance operations to reduce CO₂ produced per seat mile, decreasing the total number of flights. Since taxation provides an economic motive for airlines to seek low emissions operations procedures, it can be an effective means of achieving emissions reduction goals. Finally the use of biofuels, under some assumption of biofuel availability and cost, helps reduce emissions without compromising market demand or airline profits. ^

]]> Kushal A Moolchandani Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI1535108 http://docs.lib.purdue.edu/dissertations/AAI1535108 Wed, 22 May 2013 15:45:42 PDT A set of dynamic triaxial compression experiments at 50 MPa, 100 MPa, and 200 MPa confinement have been conducted with a modified Kolsky bar on cylindrical ultra high strength concrete Cor-Tuf specimens of diameter 19 mm and length of 12.7 mm. The experiment is composed of a hydrostatic phase which occurs at a quasi-static strain rate followed by a dynamic shear phase which occurs at a high strain rate. A set of 28 experiments were conducted at strain rates of 100 s⁻¹ and 200 s⁻¹. The experiments show that the fracture strength of the material increases under the test conditions. The specimens showed higher strength in the dynamic confined experiments than both the quasi-static TXC tests and the unconfined dynamic tests. The strength increase was attributed to specimen size difference and not a strain rate or confinement effect. Although the trend towards brittle ductile transition is observed the specimens were not tested in a high enough confinement for the phase change to occur.^

]]> Alex B Mondal Engineering, Aerospace|Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI1535079 http://docs.lib.purdue.edu/dissertations/AAI1535079 Wed, 22 May 2013 15:45:41 PDT Liquid film cooling is an important method for cooling the walls of a liquid rocket engine. Mass transfer via entrainment decreases the effectiveness of the film coolant and it is therefore important to estimate the amount of film coolant that establishes itself along the wall of a combustion chamber if the coolant flow rate is to be optimized. However, film entrainment research is limited in regards to film cooling applications in rockets. The correlations and theories that have been published are often limited in scope and have only been tested at momentum fluxes that are an order of magnitude less than those typically experienced in rockets. Experimental research has been conducted in a cold-flow test article at AFRL in order to investigate the effects of the gas stream momentum flux on the coolant flow rate that remains attached to the wall. Specifically, the objective of this study was to investigate the establishment of a shear driven liquid film introduced into a rectangular test section by a .38 mm X 25.4 mm slot, perpendicular to the stream-wise direction of the gas phase. A secondary objective of this thesis was to investigate the ability of several diagnostics to measure the interfacial shear stress, mean film thickness, and the film mass flow rate of a liquid water film shear-driven by nitrogen gas in cold flow conditions. Ultimately, a film removal slot was chosen to measure the film mass flow rate, differential pressure taps were chosen to indirectly deduce the interfacial shear stress by measuring a stream-wise pressure drop, and a laser focus displacement meter was chosen to measure the liquid film thickness. Lastly, a high-speed video camera was used to obtain qualitative visual data of the surface of the shear-driven liquid film. ^ Experiments were conducted during June and November 2011 in order to accomplish the objectives of the thesis. The experimental apparatus consisted of a rectangular channel through which nitrogen gas flowed at momentum fluxes ranging from 2.5 to 110 kPa. A liquid water film was introduced into the test section at flow rates ranging from .0034 kg/s to .018 kg/s through a .38 X 25.4 mm slot that was perpendicular to the gas flow. In the experiments described herein, the film removal slot failed to completely remove the entire film, and, therefore, the results from the film removal slot were inaccurate. However, from the data that was obtained, it appears as though the liquid that becomes entrained into the gas phase increases with both increasing gas phase momentum flux and injected liquid flow rate. The amount of liquid entrained appears to vary from about 20 to 60 % of the injected liquid flow rate for the conditions studied. In addition, the correlations for entrainment proposed by several other authors did not agree well with the data that was obtained nor each other. The pressure drop data that was obtained was inaccurate due to problems with the flow, an electrical error, or leaks in pressure lines. Due to difficulties encountered with the differential pressure transducers, it is not recommended that the interfacial shear stress be estimated from pressure drop data. The thickness of the liquid film was shown to decrease with increasing gas phase momentum flux and increase with increasing liquid film flow rate. The film thicknesses measured ranged from 4 µm at the highest momentum fluxes and lowest liquid flow rates to 160 µm at the lowest gas phase momentum fluxes and highest liquid flow rates, with a 25 % relative uncertainty. The film thickness that were measured were of the same order of magnitude as estimated or measured for similar conditions by other researchers. A numerical model was used to determine an upper bound on the film thickness results, and the experimental results fell below and exhibited the same trends as the upper bound. It was also discovered that the turbulent surface of the liquid film and entrained liquid droplets at high momentum fluxes adversely affected the ability of the LFD to directly detect the surface of the liquid film. A new method for using the LFD to measure film thicknesses based on geometric optics is proposed. However, the results obtained by this new method still require further validation.^

]]> Ryan P Miller Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI1535078 http://docs.lib.purdue.edu/dissertations/AAI1535078 Wed, 22 May 2013 15:45:40 PDT Epicormic buds and branches are a common occurrence on trees and are an integral part of woody plant development. They allow trees to respond quickly to changing environmental conditions by providing secondary meristems capable of capturing newly available light or refoliating a tree following damage. However, epicormic branches also produce knots in lumber and have the potential to cause losses in economic value when they form on tree boles. As a result, epicormics can be a major silvicultural and tree improvement problem for high value tree species. Since epicormic development has generally been thought of a function of tree vigor and genetics, the main objective of this project was to assess the relative influence of these two components on epicormic development in white oak (Quercus alba L.) and other common eastern North American oak species. ^ Because epicormic branching has not been a widely studied topic, no published review of the literature is available. Chapter 1 encapsulates descriptions of epicormics in tree species from around the world and identifies common trends among them. Research has demonstrated that the number of epicormic branches on a tree at any point in time is influenced by epicormic bud dynamics. Further, epicormic development within a given species is likely a predictable trait. By understanding epicormics in the terms of the epicormic strategy, the relative influences of environment and genetics on different stages of epicormic ontogeny can be determined. ^ The remaining chapters focused on understanding epicormic development in eastern North American oak species. For Chapters 2 and 3, a crop tree release (CTR) treatment was implemented in a 25 year old white oak progeny test with trees of known families. Chapter 2 describes the development of epicormic branches on the released study trees over a period of three years in relation to tree vigor and genetics. Overall, there was no significant increase in the mean number of epicormics per study tree (p = 0.940), but a significant (p < 0.001) increase in the size of those branches. Genetics and tree vigor appeared to influence epicormic development differently, with individual families having a stronger influence on the size of branches (dˆ = 0.228) than on the number ( dˆ < 0.001). Relative to genetics, vigor components were more important predictors of epicormic branch characteristics. However, pre-treatment epicormic characteristics had a stronger influence than either genetics or vigor on the overall epicormic response. ^ In Chapter 3, trees that were removed in the course of the CTR treatment in Chapter 2 were used to analyze the development of epicormics prior to silvicultural intervention. The internal structure of these logs was recreated using computed tomography (CT) scanning. The development of epicormics over time was assessed by counting structures and classifying them in terms of different stages of epicormic development. This portion of the study showed that variables related to ontogeny and tree vigor had strong influences on epicormics dynamics, but that the genetic component was minor. The number of sequential branch knots was the most significant predictor (p < 0.001) of numbers of epicormics, while diameter growth was strongly related with epicormic control (p < 0.001). ^ The final component of this project was an assessment of the importance of 23 vigor, site and exposure related variables on epicormic development in merchantable oak stands across the state of Indiana. For this study, 21 clearcuts from 8 sites with an average time since harvest of 3.5 years were selected. Site related variables were generally less important than tree vigor related variables. Overall, tree diameter was the most important variable; large trees (> 38.9 cm dbh) and stands with larger average tree diameters were less prone to epicormic branching. There was a significant difference in average branch numbers between white oak, which had the lowest number of branches (x¯ = 4.41) and black oak ( Q. velutina Lam.), which had the most (x¯ = 9.1, p = 0.042).^

]]> Andrew Meier Agriculture, Forestry and Wildlife http://docs.lib.purdue.edu/dissertations/AAI1535077 http://docs.lib.purdue.edu/dissertations/AAI1535077 Wed, 22 May 2013 15:45:39 PDT Across all industries, the expense of training individuals in the operation of the required equipment directly affects the profitability of the company. The construction industry is now trending into the realm of virtual reality (VR)-based simulators, a new cost-cutting, safer technology for training equipment operators. With increasing fuel costs and the continued advancement in computer technology, simulators are a logical progression for training. There are multiple commercial sources for construction simulators including at least four major equipment manufacturers. The effectiveness of any simulator depends on how well the trainee is prepared to complete the real task, or how well the skills transfer from the simulator to the real task. Rather than look at the effectiveness of simulators for inculcating skills that transfer to real life situations, this research explores the following question: Does experience with playing video games create an existing skill set that facilitates a person's aptitude for performing effectively on the simulator? Two groups of subjects, one that avidly plays video games and one that does not, were utilized in an experiment in this research to address this question. The subjects performed a variety of tasks on a construction excavator simulator, and the group who avidly played video games demonstrated superior perceptual-motor skill as evidenced by significantly better performance on the simulator training tasks. These results led to the conclusion that those who avidly play video games do have better initial ability on the construction excavator simulator than those who do not play video games.^

]]> Timothy Brian McClure Engineering, Civil|Education, Technology of|Education, Vocational http://docs.lib.purdue.edu/dissertations/AAI1535076 http://docs.lib.purdue.edu/dissertations/AAI1535076 Wed, 22 May 2013 15:45:38 PDT Tests of reinforced concrete beams have shown that as the depth increases, unit shear strength decreases. Researchers have warned of the potential danger that this phenomenon, commonly referred to as size effect, could have on the shear strength of structural members with depths larger than 24 in. and no web reinforcement. In this study, the influence of beam depth on the unit shear capacity of reinforced concrete rectangular beams without web reinforcement is examined for test specimens that have all dimensions (width, bar diameter, bar spacing, cover, and maximum aggregate size) scaled in proportion to depth. ^ This experimental program consisted of four 30-in. deep beams and six 12-in. deep beams, all simply supported and loaded at midspan to failure. All dimensions of the 30-in beams were 2.5 times the dimensions of the 12-in. beams. Four beams had a shear span-to-effective depth ratio of 2.9. The other six beams had a shear span-to-effective depth ratio of 2.3. ^ The test results indicated that when all of the beam dimensions were geometrically scaled in proportion to the depth, increasing the size of the beam (within the ranges tested) had no discernable effect on the unit shear strength.^

]]> Kaylor A McCain Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI1535075 http://docs.lib.purdue.edu/dissertations/AAI1535075 Wed, 22 May 2013 15:45:37 PDT Significant ecological concerns and attractive financial opportunities are raised by growing deposits of waste coal fines in the United States. Roughly 2 billion tons of waste coal fines are stored in impoundments in the United States and approximately 50 million additional tons are generated annually. These fines can be utilized by extrusion or roller press briquetting along with a binder to impart mechanical strength and water resistance to the briquettes. In this study, a variety of binder materials were considered and were evaluated on seven criteria: cost, availability, binding ability, processability, water resistance, heating value, and toxicity/environmental impact. Municipal solid waste (MSW) plastic binders are the primary focus in this study due to their excellent performance in all areas. The goal of this study was to characterize a briquetted coal product, using waste plastics, which may be an economically and ecologically viable substitute for conventional stoker coal. High density polyethylene (HDPE) and low density polyethylene (LDPE) provide water resistance to the coal briquettes, and since they do not contain chlorine will not promote dioxin or furan formation when combusted. In addition, the heating value of LDPE is 46.4 MJ/kg—over double that of the 21.9 MJ/kg waste coal fines used in this study. A 10 wt% LDPE-90 wt% coal mixture was found to have an 11% higher heating value over the neat waste coal fines. A number of coal/LDPE mixtures were briquetted with varying coal particle size distributions, moisture content, and LDPE concentrations using a laboratory-scale roller press briquetter. To examine mechanical robustness, briquettes were subjected to compressive testing and tumbler testing according to ASTM D 441-07. Thermal analysis of the briquetted fuels using thermogravimetric analysis/simultaneous differential scanning calorimetry (TGA/DSC) in air revealed a significant interaction between coal and LDPE. Laboratory-scale combustion tests revealed a dependence of combustion efficiency on LDPE concentration in the briquetted fuel. Gas chromatography of effluent gas at 3 minutes validated this trend. The results of this work indicate that HDPE and LDPE can serve as excellent waste coal binders due to their high energy density, water resistance, binding ability, and relatively low cost.^

]]> Matthew M Massaro Engineering, Mechanical|Plastics Technology http://docs.lib.purdue.edu/dissertations/AAI1535061 http://docs.lib.purdue.edu/dissertations/AAI1535061 Wed, 22 May 2013 15:45:36 PDT Diplodia ear rot caused by Stenocarpella maydis is considered the most common ear rot pathogen in hybrid corn, and seed quality is compromised in infected ears. The absence of high levels of resistance makes it necessary to explore alternative options for management. The objectives of this study were i) determine the efficacy of fungicide applications for Diplodia ear rot and ii) identify and map resistance to Diplodia ear rot by screening a population of recombinant inbred lines (RIL). Field experiments were conducted during 2011 and 2012 at two locations in Indiana to determine efficacy of the fungicides Quilt Xcel^® (azoxystrobin + propiconazole; Syngenta Crop Protection) and Proline^® (prothioconazole; Bayer Crop Science) on disease severity. The experimental design was a split-plot with inoculation treatment as the whole plot, and fungicide application timing as the subplot. For plants receiving an inoculation treatment, S. maydis colonized sorghum was placed in the whorl at the vegetative growth stage V7. Fungicide treatments were applied at the label rate of each fungicide when plants were at the vegetative growth stage V6, tasseling/silking (R1), or kernel milk stage (R3). Results indicated that fungicide treatment did not significantly reduce disease severity for any application time, in either non-inoculated or inoculated plots in both 2011 and 2012. To identify potential quantitative trait loci (QTL) and molecular markers associated with resistance to Diplodia ear rot, a study was conducted near Lafayette, Indiana on the corn intermated B73 x Mo17 (IBM) population of recombinant inbred lines (RIL). This population was planted in 2010, 2011 and 2012. Each line was inoculated at the growth stage V7 with sterilized sorghum seed colonized with S. maydis. Analysis of the data detected a single QTL each year for 2010 and 2011. No QTL was detected in the 2012 due to adverse environment conditions that reduced ear production and population size. This study provides new information for corn producers about the efficacy of applying fungicides to control Diplodia ear rot. Although a QTL consistent over the three growing seasons was not identified, one line was identified as highly resistant and needs further evaluation. Also, enhancements in progeny type and population size need to be considered before establishing further QTL mapping studies with this IBM population.^

]]> Martha Patricia Romero Luna Agriculture, Plant Pathology http://docs.lib.purdue.edu/dissertations/AAI1535060 http://docs.lib.purdue.edu/dissertations/AAI1535060 Wed, 22 May 2013 15:45:35 PDT Sulfur (S) is often an overlooked secondary nutrient in today's agronomic cropping systems, especially for cool season crops. The objective of this study was to determine optimum rates of nitrogen (N) and S in a field low in S. A field experiment was conducted near Vincennes, Indiana from fall 2009 through fall 2011 on an Ade loamy fine sand (Coarse-loamy, mixed, superactive, mesic Lamellic Argiudoll). The first year of the study was initiated with winter wheat (Pioneer 25R54) in the 2009-10 growing season followed by double-crop soybean (Pioneer 94Y06) in 2010. Experimental design was a 4 x 5 factorial with 4 replications. Treatments were arranged in a randomized complete block design with 4 S rates of 0, 17, 34, and 50 kg S ha^-1 and 5 N rates of 0, 45, 78, 112, and 146 kg N ha^-1. Fertilizer was applied on March14, 2010 when wheat broke dormancy. In year two, winter wheat (Pioneer 25R54) was planted in 2010-11 growing season, followed by double crop soybean (Pioneer 94Y06). The second year was to investigate the residual impact of S applied in 2010 versus a second application in 2011. The second study year used a similar experimental design of split plot 4 x 5 factorial with 4 replications in a randomized complete block design in the same treatment plots as the first study year. The same treatments of N were applied to the whole plot as the first year, however S was only applied to half of each respective plot on March 18, 2011. ^ This site in Vincennes, IN was severely S deficient in the early spring 2010 growing season, which was confirmed through visual observations and tissue N:S ratios greater than 16:1 for the 0 kg S ha^-1 application rate at wheat Feekes growth stage 6. However, as the growing season progressed disease development and lodging limited response to S application. Greater S availability from atmospheric deposition and S mineralization as the season progressed may have also contributed to recovery from S deficiency. The 2010 double crop soybean crop responded to S fertilization with increased tissue S, although grain yield and biomass at harvest did not increase with S fertilization. ^ Approximately 70% of the SO₄-S applied in spring of 2010 was leached from the soil profile during the 2010-11 winter months following double crop soybeans. A majority of the SO₄-S remaining in the profile was below 60 cm depth, providing little residual benefit to the next wheat crop. ^ Heavy rainfall and flooding in the spring of 2011 prevented almost all data collection for 2011 wheat; except for harvested grain collection for elemental analysis. Despite weather conditions, only about half the SO ₄-S applied in March 2011 was lost from the 90 cm soil sampling depth. ^ Though soil SO₄-S in the 0 kg S ha^-1 treatment where S was applied in 2010 was extremely low (< 2 mg kg^-1 throughout the upper 60 cm) in June 2011, there was no soybean yield or biomass benefit of S fertilization. Even when the 2011 soybean leaf tissue S concentration at flowering was considered low (N:S > 16) without S fertilization there was no yield decrease. ^ In conclusion application of S had no benefit for yield in wheat or soybean in 2010 or in 2011. However early in the 2010 growing season S was deficient, which was shown in wheat tissue samples. Plus application of S increased plant S accumulation especially in soybeans. The application of S increased soil SO₄-S, but soil SO₄-S decreased rapidly during winter rainfall with little residual SO₄-S in the soil profile in 2011 from the 2010 S application.^

]]> Stephen Maloney Agriculture, Agronomy http://docs.lib.purdue.edu/dissertations/AAI1535058 http://docs.lib.purdue.edu/dissertations/AAI1535058 Wed, 22 May 2013 15:45:34 PDT Experimental validation of physics-based transition models is essential to improving the state of the art of hypersonic vehicle design. This research focuses on one aspect of this problem, which is the effect of surface roughness on the non-linear breakdown of second-mode waves in hypersonic boundary layers. ^ A flared cone was designed to allow non-linear growth of second-mode waves to sufficient amplitudes to lead to transition under quiet flow in the Boeing/AFOSR Mach 6 Quiet Tunnel. The non-linear breakdown process is characterized by a set of streamwise streaks of increased heating, followed by the onset of turbulence. The location of the streaks is related to small amounts of upstream surface roughness. ^ Techniques for applying and fabricating surface roughness were developed. These are to be used to manipulate this breakdown process. While certain types of roughness have been used to introduce streamwise vorticity in other flows at low speeds, it was unknown what types of roughness would work in the present case. The effects of the new roughness types were analyzed through pressure measurements and global heat transfer visualization using temperature sensitive paint. None of the new roughness types was able to directly control the spanwise periodicity of the streaks, but two types were identified as good candidates for future testing. More work is required to develop a suitable technique for fabricating and applying small roughness.^

]]> Ryan P. K Luersen Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI1535059 http://docs.lib.purdue.edu/dissertations/AAI1535059 Wed, 22 May 2013 15:45:34 PDT White layer is a generic term for a light etching surface layer on metal alloys that can result under extreme deformation conditions in wear, sliding or machining. While there has been some characterization of white layer due to abusive machining, the specific effect on fatigue crack initiation life has not been well documented. This study aimed to establish a relationship between the presence of white layer due to abusive machining and fatigue crack initiation life in a wrought nickel based superalloy (Udimet ^® 720). ^ Low cycle fatigue testing was conducted on large specimens containing through holes drilled with parameters aimed at creating holes with and without white layer. Initially, Acoustic Emission monitoring technologies were used to monitor for acoustic events associated with crack initiation, however, this technology was deemed unreliable for this testing. Instead, cycles to crack initiation was determined using striation density measurements on each fracture surface to estimate the number of cycles of crack propagation, which was subtracted from the total number of cycles for the specimen. A total of sixteen specimens were tested in this manner. ^ The results suggested that the crack initiation lives of holes machined with good machining parameters were statistically longer than crack initiation lives of holes machined with poor machining parameters. The mean initiation life of the poorly machined specimens was a factor of approximately 2 times shorter than the mean initiation life of the well machined specimens. The holes machined with good machining parameters exhibited subsurface initiations which suggested that no anomalies affected crack initiation for these specimens. It was also shown that some of the poorly machined holes exhibited subsurface initiations rather than initiations at white layer damage. These holes had better surface finish than the poorly machined specimens that did fail at white layer. The mean initiation life of the poorly machined holes with subsurface initiation was 7 times longer than the mean initiation life of the holes that exhibited white layer at the crack origins. Lastly, no apparent correlation between white layer thickness and initiation life was demonstrated in this study.^

]]> Christine M Magadanz Engineering, General|Engineering, Aerospace|Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI1535057 http://docs.lib.purdue.edu/dissertations/AAI1535057 Wed, 22 May 2013 15:45:33 PDT Two studies were performed for this thesis. In study 1, effects of antibiotic alternatives on growth performance and immune response of broiler chickens challenged with Eimeria oocysts in coccivac B vaccine were investigated. The study was a randomized complete block design with 6 treatments and 8 replicate pens per treatment. The six treatments tested were; negative control (NC) with neither antibiotic nor antibiotic alternatives, Salinomycin positive control (PC), essential oil (Orego-Stim^®), commercial yeast (Alphamune™), direct fed microbial (Avicorr^{® ®}) and crude yeast extract. The study lasted 42 d and measurements were taken on d 21 and 42. There was no significant difference in the final body weight (BW), daily gain (BWG) between treatments on d 21. However, d 42 BWG of birds supplemented with Salinomycin was higher (P < 0.05) than the Avicorr and Orego-Stim treated groups. Additionally, feed efficiency was improved (P < 0.05) by Salinomycin compared with NC and Orego-Stim treatments. Expression levels of genes were not different among treatments on d 21. However on d 42, lipopolysaccharide- induced TNF-alpha factor (LITAF) was lower (P < 0.05) in the Orego-Stim treatment group than NC. In addition, birds treated with crude yeast had higher (P < 0.05) level of IL-10. Similarly, IFN-γ and TLR-4 were lower with Orego-Stim supplementation and higher with crude yeast (P < 0.05). In the digestibility trial, Salinomycin and crude yeast treated birds had higher apparent ileal DM, energy, N and P digestibility on d 21. However, these differences were no longer apparent on d 42. Overall, these results confirm the expected improvement in animal performance with antibiotic (Salinomycin) and further show reduced bio-markers of inflammation with organic acid (Orego-Stim) treatment in broiler chickens. ^ Study 2 was conducted to determine the effects of combination of carbohydrases and phytase on performance, nutrient digestion and absorption, gut health and integrity, and immune status of broiler chickens. A total of 448 day-old broilers were randomly assigned to 4 treatments including a positive control (PC, meets the nutrients requirements by NRC,1994), a negative control (NC, deficient in ME, CP, Ca and nPP, relative to the PC, by 100 kcal/kg, 5g/kg, 1.1g/kg and 1.6g/kg) and 2 test diets with Rovabio^® Max at 0.05 and 0.075 g/kg diet. On d 21 and 42, one bird per pen was killed for gene expression analyses of mucin (MUC2), interleukin 1 (IL-1β) and phosphorus transporter (NaPiIIb) by RT-PCR in mucosal samples from the duodenum, jejunum, ileum. Five birds per pen were moved to steel cages for the digestibility study on d 21 and 42. Body weight (BW) and average daily gain (ADG) were linearly increased by Rovabio^® Max supplementation on d 21 and 42 (P < 0.05). Rovabio Max linearly increased the feed intake (FI) from d 21 to 42 and overall (P < 0.05). The gain to feed ratio was significantly (P < 0.05) improved by Rovabio^® Max from day 0 to 21, d 21 to 42 and overall. Additionally, higher serum phosphorus (P) was observed with Rovabio^® Max addition to the diets (P < 0.05). There were no gene expression differences between treatments. In the digestibility experiment, on d 21, there were no significant differences in dry matter (DM), energy and nitrogen (N) apparent ileal digestibility (AID). However the AID of P was increased by Rovabio ^® Max (P < 0.05) by 119%. On d 42, Rovabio ^® Max increased the AID of DM, energy, P and N (P < 0.05) by 9.4%, 8.5%, 21.7% and 5.0% respectively. Overall, these results confirm that Rovabio^® Max supplementation leads to improvement in growth performance of broiler chickens and also resulted in increased energy and P utilization.^

]]> Hang Lu Agriculture, Animal Culture and Nutrition http://docs.lib.purdue.edu/dissertations/AAI1535056 http://docs.lib.purdue.edu/dissertations/AAI1535056 Wed, 22 May 2013 15:45:32 PDT Bird strikes account for an annual loss of $650,000,000 in the United States due to aircraft loss, damage, and delays; worldwide, there have been nearly 219 deaths since 1988. Investigations into novel methods of deterring birds from striking planes could ultimately lead to a decrease in loss of life and damage caused to aircraft. Previous observations suggest three things: 1) birds respond to aircraft as they would a predator, 2) birds can detect different levels of microwave frequencies and 3) birds might respond to microwaves produced by weather radar. The goal of this study was to determine whether birds react to microwaves produced by radar in the same way as they do to predators. I used wild caught European Starlings (Sturnus vulgaris ), which were exposed to two treatments (radar or a stuffed ground predator) in an enclosure under semi-natural conditions. I found that the behavioral responses to the radar differed from those to the predator. When starlings were exposed to the predator, they moved and flew around the enclosure more frequently, moved their heads faster and hung from the walls of the enclosure longer, likely to track the predator visually. However, when starlings were exposed to the radar, they moved less and reduced their head movements. I did not find significant differences in the time to detect the radar compared to the predator. When starlings were exposed to the radar some body parts (back, cheek, chest, chest, and neck) had higher temperatures than when exposed to the predator; but I found the opposite temperature effect in their eyes and mouth. These results suggest that Starlings respond to radar by reducing their locomotive and visual exploration behaviors and increasing the temperature of some body parts, which may be associated with the hyperthermic effects that microwaves can cause in animals. Future work should focus on how these responses may vary at different distances from the radar, which could have implications for the potential use of these devices to minimize bird strikes. ^

]]> Juanita E Losier Biology, General|Biology, Ecology|Psychology, Behavioral http://docs.lib.purdue.edu/dissertations/AAI1535055 http://docs.lib.purdue.edu/dissertations/AAI1535055 Wed, 22 May 2013 15:45:31 PDT The Indiana manufacturing sector held the largest share of jobs and output in the Hoosier State during 2010 and has been one of the state's prominent industries dating back to Bureau of Economic Analysis records in the late 1960s. Manufacturing output increased from 72,732 million dollars (inflation adjusted) to 74,917 million dollars between 2000 and 2010 despite 211,386 (or 31.3%) less manufacturing jobs. The increases in output attributed to capital investment and reduction in labor suggests a structural change within the sector. ^ This thesis analyzed the location decisions of manufacturing investment in the restructured Indiana manufacturing sector. Prior manufacturing location choices have been based on markets, labor, agglomeration, infrastructure, and fiscal factors. This analysis suggests that firms' site selection is based on market access. This does not imply that labor, agglomeration, infrastructure, and fiscal factors are unimportant in the location process. It rather indicates that their roles may have changed in the location process or perhaps that all prospective sites that firms consider may have these attributes. The results could also suggest that the importance of the insignificant attributes is not uniform between firms, indicating that some factors are more relevant than others in location decision process. ^ This thesis also examined the relationship between job growth and population growth in the restructured economy. This includes understanding if individuals relocate in search of employment opportunities. The relationship between people and jobs was analyzed using a simultaneous equation modeling approach and labor, market, agglomeration, infrastructure, and fiscal factors. ^ Communities that experience job growth might see lagged population growth as people migrate to these cities in search of employment opportunities. Communities experiencing job growth might essentially see increasing unemployment as people migrate into these communities in search of employment opportunities. Job growth is more prevalent in urban areas and may be an indicator that the economic health of rural communities is in question if indeed people follow jobs.^

]]> Joseph William Longley Economics, Agricultural http://docs.lib.purdue.edu/dissertations/AAI1535054 http://docs.lib.purdue.edu/dissertations/AAI1535054 Wed, 22 May 2013 15:45:30 PDT The objective of this research work is to assess the capability of the lagged eddy viscosity model in predicting separated flows over wind turbine airfoils at subsonic flow conditions. Pressure driven flow separation is an important category of flows and many aerodynamic devices are required to operate on the verge of boundary layer separation to maximize efficiency. Current one- and two-equation turbulence models do not capture all the relevant physics associated with flow separation and, hence, result in erroneous predictions. The lagged eddy viscosity turbulence model is a new model proposed as an improvement over existing two-equation based models. In this model an additional transport equation is solved to account for history effects, which become predominant for non-equilibrium flows, such as separated flows. This model was implemented in the NASA CFD code, OVERFLOW, and has shown promising results in predicting separated flows under high speed or supersonic flow conditions. ^ In the current study, the lagged eddy viscosity turbulence model is implemented in the commercial CFD software FLUENT and CFX. An additional transport equation for the non-equilibrium eddy viscosity is solved using user defined functions in FLUENT and through expressions in CFX. Compared to FLUENT, CFX has the option of an additional turbulence model (EARSM) and also allows the option of simulating natural transition flows by lagging the eddy viscosity of the four-equation SST transition model. Hence, CFX was used for all the flow computations. To ensure proper implementation of the lagged eddy viscosity model, zero pressure gradient flow over a flat plate and flow inside an asymmetric diffuser are computed using the standard k– ω, SST k– ω and EARSM models and compared to computations using the lagged eddy viscosity model and results from experiments. Airfoils with thickness to chord ratios of 18% (DU96-W-180) and 25% (DU91-W2-250) were considered for this study. The standard k– ω and SST k– ω models predicted a delayed separation and stall. EARSM, although it performed better than SST k– ω, did not predict stall to the desired level of accuracy. The lagged eddy viscosity model with the original parameters for σ _kA and a₀ as recommended by Olsen behaved similarly to SST k- ω; however, the lag model showed significantly improved separated flow prediction capability for modified parameter values for σ _kA and a₀.^

]]> Jaikumar Loganathan Engineering, General|Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI1535053 http://docs.lib.purdue.edu/dissertations/AAI1535053 Wed, 22 May 2013 15:45:29 PDT Integrated effects of genetic host resistance and fungicide (chlorothalonil, Daconil Ultrex 82.5WG) for controlling dollar spot were evaluated on three modern creeping bentgrass (Agrostis stolonifera L.) cultivars, including Independence, Penncross and Declaration. During 2011 and 2012, four runs of 21-day period "resistance experiments" and two runs of season long "threshold experiments" were conducted. The resistance experiment consisted of a single Daconil Ultrex 82.5WG application at rates of 0, 1.675, 3.35, 5.025, 6.7, 8.375 kg a.i. ha^-1 to three replications of each cultivar. The threshold experiment consisted of multiple Daconil Ultrex 82.5WG applications at the rates of 0, 4.31 and 8.62 kg a.i. ha^-1 based on predetermined application thresholds to six replications of each cultivar. Both experiments showed that the Declaration can ahiceve a better dollar spot control than the other two cultivars with less fungicide applications. We also attempt to quantify host resistance in terms of the amount of fungicide required to achieve a given level of control had mixed results.^

]]> Yang Liu Agriculture, Plant Pathology http://docs.lib.purdue.edu/dissertations/AAI1535052 http://docs.lib.purdue.edu/dissertations/AAI1535052 Wed, 22 May 2013 15:45:29 PDT This study explored the Bluetooth vulnerabilities of mobile phones and how those vulnerabilities can be utilized by attackers to control mobile phones and gain personal data. The researcher conducted attacks on mobile phones under varying conditions in order to verify the efficacy of two attacks, Bluesnarfing and Bluebugging. This method tested improvements in Bluetooth security features by using attack verification. In other words, if an attack is designed to make use of the vulnerabilities of Bluetooth 1.0, then the newer version, Bluetooth 2.0, should have a proposed solution designed to fix these vulnerabilities. This study demonstrated that the security features of Bluetooth have been improved to defend against Bluesnarfing and Bluebugging. However, other Bluetooth threats were found, including lack of verification for connections following the first connection, over-supported functions, and the implementation of discovery mode. The implementation and design may also cause leakage of users' information leakage.^

]]> Mengjun Liao Information Technology|Engineering, Electronics and Electrical|Information Science http://docs.lib.purdue.edu/dissertations/AAI1535051 http://docs.lib.purdue.edu/dissertations/AAI1535051 Wed, 22 May 2013 15:45:28 PDT Farming is a risky operation. In recent years, farmers' incomes have been increasingly volatile due to variation in crop prices, crop productivity, fertilizer expense, farmland cash rents and farmland values. Previous studies focus on those variations separately. There has been little research on analyzing financial performance of a set of representative farms under a combination of risks from prices, costs and productivity. In the first part of this study, a parametric stochastic simulation was used to model price and yield of corn and soybean, fertilizer price, cash rent and farmland value for a three-year period from 2012 to 2015. In the second part, a test was performed on financial performance of a set representative farms with various scales, farmland ownerships, and capital structures in Central Illinois under the shock of simulated price, yield and expense with the presense of crop insurance and crop hedge using futures. Management adjustments were implemented for situations of excess or insufficient cash balances within the simulation period. Results were analyzed and compared. Larger farms were found to be more likely to obtain financial success with their farm businesses. Farms with lower farmland ownership were found to have higher possibilities of insufficient cash balance to meet all financial obligations and have to either finance the cash insufficiency with further borrowing or shrink their farm business due to high cash rent expense crashing farm revenues. Farms with a capital structure of lower debt proportion were found to be more likely to meet all financial obligations with cash generated from farm operation, while a higher debt load made the farm business risker because the deviation in rate of return on equity increased and the possibility of having an insufficient cash balance was increased when the debt-to-asset ratio increased..^

]]> Shasha Li Economics, General|Economics, Agricultural http://docs.lib.purdue.edu/dissertations/AAI1535049 http://docs.lib.purdue.edu/dissertations/AAI1535049 Wed, 22 May 2013 15:45:27 PDT What are the critical capabilities that middle and upper level managers in retail agribusiness firms need to lead their firms successfully in the future? This is the central question of this study. ^ A survey of CEO's in large retail agribusiness firms examines their perceptions of the critical drivers of change and key success factors in their competitive environment for their firms. Then, given these environmental changes these same CEO's are asked to identify the critical skills and behaviors that managers within their businesses will need to exhibit to allow the firm to compete effectively in the new environment. Individuals maintaining a leadership role at their firm or cooperative can use this information to craft strategies going forward, which may be more suitable to the imminent turbulent events that are characteristic of the agricultural industry. By identifying the critical skills and behaviors, the leaders will also be able to formulate succession plans or develop employees who can lead their organization successfully. ^ Since firms in the agricultural industry are constantly subjected to changes in environment, future leaders need to continue developing their skills and competencies to minimize any potential skill gaps, especially those related to results, thought, personal, people leadership. This study seeks to identify what the important key driving and success factors are. The data indicate that industry leaders have a high degree of agreement on the most important external and internal influences of success for their industry. The study also tested the hypothesis that employees in a firm, years of experience of a leader, average annual sales, and competitive intensity having a statistically significant impact on the firm's perception of external influences, internal influences, and leadership areas. The statistically significant results of this analysis suggest that in competitive environments that are anticipating intense rivalry for key dimensions of competition in the future, leadership development needs to be centered on specific leadership areas. In most cases, rising levels of competitive intensity can result in a shift in leadership needs and individuals who have adept abilities in key leadership skills and competencies will be able to respond better to changes in market conditions. The study also tested the hypothesis that the perceptions of the CEO's on external and internal influences can dictate how important leadership skills are; results show that there are no statistically significant marginal effects. The reason that could be behind this that there is little variation identified surrounding many of the measured influences in the industry forcing the multinomial logit analysis, which intends to exploit variation, to produce statistically insignificant results. ^ The findings send signals to current and future leaders in the crop input retail industry. Each leadership area has subcomponents that can help guide current strategists and future leaders in their attempt to navigate their organization through an amorphous industry that is characteristic throughout the agricultural sector. Under the many different circumstances which can arise in this industry, specific leadership development actions can be taken to ensure the success of their organization as it relates to the leadership skills and competencies. By anticipating what is in the future for the crop input retail industry, plans can be made to nurture or equip employees with the necessary capabilities using the many frameworks have been introduced by numerous authors. Finding a matching framework for a firm may be a matter of preference. This study operates under the Sveiby's framework of intangible assets which focuses on three components: the external structures, internal structures, and employee competencies. Other frameworks differ by creating a cyclical effect which recycles and spreads skills through sharing of information such as the framework proposed by Arthur Anderson and the American Productivity and Quality Center. With the knowledge management frameworks infused with the critical skills capabilities needed for the future, the leader of the firm or cooperative can navigate through the agricultural industry at a greater advantage than others who do not make this effort.^

]]> John H Lai Business Administration, General|Business Administration, Management|Economics, Agricultural http://docs.lib.purdue.edu/dissertations/AAI1535050 http://docs.lib.purdue.edu/dissertations/AAI1535050 Wed, 22 May 2013 15:45:27 PDT Work-family balance is an increasingly salient issue associated with Bed-and-Breakfast (B&B) innkeepers (Hsieh, 2010). The lack of spatial boundaries between home and workplace makes it difficult for B&B innkeepers to separate activities in the work domain from those in the family domain. However, issues related to borders between work and family domains faced by innkeepers have received limited critical attention (Hsieh, 2010). By integrating the work-family border theory (Clark, 2000) and the entrepreneurial motivation literature, the present research seeks to develop a theoretical framework to understand the relationships among work-family border characteristics (i.e., border tangibility and border strength), entrepreneurial motivation, work-family integration, and balance within the B&B business. A web-based survey was conducted among 369 innkeepers recruited through the Professional Association of Innkeepers International (PAII). The results of hierarchical regression analysis indicate that border tangibility is positively related to work-family balance and the relationship between the two is fully mediated by work-family integration. However, border strength is negatively related to work-family balance and this relationship is direct and not mediated by work-family integration. In addition, entrepreneurial motivation moderated the relationship between work-family integration and work-family balance. Innkeepers with a lifestyle motivation enjoy greater work-family balance than those with a business-oriented motivation when work and family are highly integrated. The present research contributes to the hospitality literature by assessing border tangibility related to physical, temporal, and relational borders between innkeepers' work and family domains and by examining how border characteristics and entrepreneurial motivation influence work-family balance in the B&B context. The present research also bears important implications for B&B innkeepers to create and maintain borders with desirable levels of tangibility, and to adjust the extent to which they integrate work and family based on individual needs to attain work-family balance.^

]]> Yuan Li Psychology, Industrial|Sociology, Individual and Family Studies http://docs.lib.purdue.edu/dissertations/AAI1535048 http://docs.lib.purdue.edu/dissertations/AAI1535048 Wed, 22 May 2013 15:45:26 PDT This study strives to share the experiences of a group of students participating in a study abroad program in London, England. Grounded in Dewey's (1938) idea of experiential education and Freire (1970) and hooks' (2010) idea of critical literacy, this study explores the influences which experiences abroad can have on student's critical literacy skills. The data from this study includes student interviews, student journals, and class observations. By comparing the critical literacy framework with the data, the researcher found that most themes from the data were reflected within the framework. The researcher also found that there were additional themes in the data that were outside of the critical literacy framework. Finally, the researcher offers methods for enhancing student's critical literacy skills. The methods offered are aimed toward study abroad leaders, study abroad students, pre-service teachers, and also teachers not involved in study abroad programs.^

]]> Emily J Kroeger Literature, General|Education, General http://docs.lib.purdue.edu/dissertations/AAI1535043 http://docs.lib.purdue.edu/dissertations/AAI1535043 Wed, 22 May 2013 15:45:25 PDT Alcohol abuse is a worldwide socioeconomic problem. A variety of alcohol-induced pharmacological changes have been found in the brain, yet the exact mechanisms that mediate the transition from recreational use to abuse are still uncertain. Most research has focused on the effects of very high doses of alcohol in the dependent state: however I wished to take a step back and examine the effects of moderate use leading up to this. As such, I used the alcohol–preferring rat line to examine what effects chronic, moderate use would cause in the brain. My first study analyzed the DNA methylation patterns of genes associated with alcohol preference/consumption in regions comprising the meso- and cortico-limbic circuits. However, no changes were detected in any gene in any of the five brain regions. My second study focused on the liver, the primary site for alcohol metabolism which displays multiple physiological changes following chronic use. I analyzed the hepatic transcriptome for genes altered by chronic alcohol use and discovered that 259 transcripts were altered, the majority of which were down-regulated. Ontology analysis revealed that genes involved in cholesterol biosynthesis and members of the cytoskeleton were the most overrepresented in this dataset. Finally, I profiled methylation levels in a subset of these genes and found alcohol generally caused a loss of methylation. Interestingly, the magnitude of this effect differed in gene promoters, exons, and introns, even within the same gene. In conclusion, I found that alcohol potentially regulates expression of target genes through epigenetic mechanisms in the liver. This aberrant regulation may underlie the transition to abuse by maintaining alcohol-induced changes for the long term.^

]]> Jonathon D Klein Biology, Molecular|Biology, Genetics http://docs.lib.purdue.edu/dissertations/AAI1535044 http://docs.lib.purdue.edu/dissertations/AAI1535044 Wed, 22 May 2013 15:45:25 PDT The split Hopkinson pressure bar or Kolsky bar is widely used to determine dynamic material behavior. Stress equilibrium and strain rate constancy condition must be satisfied for a valid test result. These two critical conditions have different requirements on the impedance mismatch between bars and sample. The first part of this thesis is focusing on how the impedance mismatch affects the time to achieve constant strain rate and to achieve stress equilibrium by both analytical and experimental methods. The second part is testing the compressive stress-strain response of a shock-mitigation soft rubber. ^ Analytical investigation is based on the method introduced by Frew (2001) to simulate the wave propagation inside the sample. A computer program is developed to expand the application to non-linear loading case such as rectangular step loading and step loading with an initial rise ramp. Aluminum, titanium and steel bar testing are performed in experimental investigation using ramp loading and elastic sample. The experimental results generally match model predictions. An optimum impedance mismatch range is suggested for linear loading. ^ The compressive stress-strain response of the soft rubber compound is obtained experimentally at quasi-static, intermediate and high strain rates under uniaxial stress and uniaxial strain stress states. Kolsky bars with modifications for characterizing soft material under the two specific stress states and a long Kolsky bar are used to conduct the dynamic experiments; and an MTS load frame is used for conducting tests at quasi-static rates. Experiments are conducted at every decade in the strain-rate scale without any gap typically seen in the intermediate range. The experimental results show a significant strain-rate effect on the mechanical responses for this soft material, which are summarized by a rate-dependent constitutive model. ^

]]> Hangjie Liao Applied Mechanics|Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI1535042 http://docs.lib.purdue.edu/dissertations/AAI1535042 Wed, 22 May 2013 15:45:24 PDT There are two main design issues in digital prototyping of swash plate type axial piston machines. First, the design of the rotating group with its lubricating interfaces is critical to the operation of the swash plate type axial machine. Swash plate type axial piston machines have three main lubricating interfaces - the Piston/Cylinder, the Cylinder block/Valve plate, and the Slipper/Swash plate interface. These lubricating interfaces fulfill simultaneously a bearing and sealing function. The three interfaces represent the most critical design issue within the design process of the swash plate type axial piston machine because these interfaces determine the performance and reliability of the machine and are the main source of energy dissipation. Ivantysynova and her research group (2001, 2002, 2005, 2010, and 2012) have developed fully coupled fluid structure interaction models based on non-isothermal flow through the lubricating gap for the three lubricating interfaces of swash plate type axial piston machines. The models consider the macro and micro motion of movable parts such as the piston, slipper, and cylinder block as well as the deformation of solid bodies due to pressure and temperature for all three interfaces. These models were developed separately for each interface. However, viscous friction forces generated in one interface are transferred to other interfaces, i.e. the friction force generated between piston and cylinder will load the cylinder block and therefore must be considered when calculating the cylinder block valve plate interface. Also, the friction force generated in the gap between the slipper and swash plate will act on the piston/slipper assembly and therefore must be considered when balancing forces acting on the piston. ^ The second design issue involves the valve plate design in the swash plate type axial piston machine. The valve plate is a non-rotating component in the axial piston machine that is located adjacent to the cylinder block. The valve plate connects the pump ports to the individual cylinder chambers. Proper valve plate design is essential for the high performance axial piston machine because the valve plate regulates the displacement chamber pressure profile in the axial piston machine. The pressure profile in the displacement chamber is important in regards to the axial piston machine operation because the pressure profile has a very significant influence on the resulting fluid film of each of the three interfaces, on moments acting on the swash plate, and flow ripple in the low/high pressure ports. The pressure in the displacement chamber transforms to the primary force acting on the piston/cylinder, cylinder block/valve plate, and slipper/swash plate interface. Because of the time dependent change of pressure in each cylinder chamber the resulting forces and moments are pulsating. In addition, the force acting on the slipper/swash plate transforms to the moments acting on the swash plate, which influence the controllability of the swash plate angle. The pulsating forces and moments acting on the swash plate not only have an influence on the controllability of the swash plate angle, but also represent one of the main sources of noise generated in the axial piston machine. The moment acting on the swash plate oscillates the swash plate and the end case simultaneously, which in the end results in audible noise. This noise source is often referred to as structure-borne noise (SBN). The other noise source, fluid-borne noise (FBN), is also related to the valve plate because FBN results mainly from flow ripple in the low/high pressure port. Flow ripple in the low/high pressure port is affected by the number of pistons of the axial piston machine, but it also has a strong relationship with the displacement chamber pressure. Therefore, the valve plate design significantly influences both SBN and FBN. And for this reason, much valve plate design research has been conducted in order to reduce noise in the axial piston machine. There are two types of valve plate noise reduction techniques: passive and active noise reduction technique. Of these two noise reduction techniques, the passive noise reduction technique has the advantage that it does not require any additional power source or system. However, this technique has the disadvantage that it is not effective for a wide range of operating conditions. Relief groove, pre-compression filter volume (PCFV), and cross port are examples of passive noise reduction techniques. In order to study these phenomena more accurately, Seeniraj and Ivantysynova developed a simulation tool, VpOptim, for valve plate simulation and optimization. VpOptim can be used for valve plate optimization by implementing relief grooves and the PCFV in the valve plate. (Abstract shortened by UMI.)^

]]> Dongjune Albert Kim Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1535040 http://docs.lib.purdue.edu/dissertations/AAI1535040 Wed, 22 May 2013 15:45:23 PDT This study examined the views held by graduate students in a research traineeship program regarding the nature of engineering. There is very little literature on the views held by students regarding the nature of engineering. The study sought to extend the work of an earlier study which investigated the conceptions of the nature of engineering held by undergraduate engineers to a graduate student population. The graduate students were part of an interdisciplinary engineering research traineeship program involving a solar economy. The students' conceptions of the nature of engineering generally allied with those expressed by professionals and academics in the literature. However, the students' concepts were less complete. Engineering was seen as a team endeavor to balance the often conflicting needs of the clients, society, and the environment in order to develop a product or solution to the clients' needs through problem solving. Some of the students viewed engineering as a simple application of science, while others saw engineering as a field of knowledge of its own, which interacted with the field of science in mutually beneficial ways^

]]> Steven M Kaverman Philosophy|Engineering, General|Education, Higher http://docs.lib.purdue.edu/dissertations/AAI1535038 http://docs.lib.purdue.edu/dissertations/AAI1535038 Wed, 22 May 2013 15:45:22 PDT GC/MS based metabolite profiling was used to explore potential metabolite biomarkers for Madison lung carcinoma 109 (M109) in Balb/c mice. Newly discovered biomarkers could be beneficial to both detection and follow up therapy with novel antitumor agents such as EC0225. Metabolites that were statistically significant and showed meaningful trends in duplicate analyses were categorized into two main groups. In the first group, the metabolite signal intensity decreased after tumor growth, but increased after treatment with EC0225, while in the second group the intensity increased after tumor inoculation and decreased after EC0225 was applied. ^ Urine from mice with M109 tumors showed elevated levels of quinolinic acid, phenylpyruvic acid, 2, 3-dihydroxybenzoic acid, and lactic acid. In addition, these samples showed lower levels of oxalic acid, L-homoserine, and 4-hydroxy-3-methoxybenzoic acid. These results are valuable for understanding the metabolic basis of tumorigenesis and its possible reversal with drug therapy. The validation of these potential metabolite biomarkers could enhance the application and efficacy of existing and new treatment methods against the deadliest cancer.^

]]> Elaheh Kamali Chemistry, General|Chemistry, Analytical|Chemistry, Biochemistry http://docs.lib.purdue.edu/dissertations/AAI1535039 http://docs.lib.purdue.edu/dissertations/AAI1535039 Wed, 22 May 2013 15:45:22 PDT Bicycling has been enjoying a resurgence as a commuting mode. It has been shown to be an effective way to reduce congestion and improve public health. However, in many communities, the street network was planned to serve motor vehicles and is lacking bicycle facilities. This limitation often results in bicyclists riding on the sidewalk out of concerns about safety. Therefore, this study provides a comprehensive analysis of bicycle related issues: route choice behavior, facility preferences, bicycle-pedestrian interactions on the sidewalk, and bicycle crash injuries.^ This study looks at how bicycle route choice is affected by environmental factors that characterize alternative routes available to a bicycle commuter and how changing bicycle facilities on a street segment will affect bicyclist behavior. Bicyclists were interviewed at the end of their trips on campus and asked which routes they took and which part of the cross-sections along their routes they had used – on-street or off-street. A practical procedure is developed to estimate bicycle link cost function parameters by formulating a bi-level optimization problem using route-level data. The results indicate that, for our database, travel distance is more important in route choice decisions. However, when perceived risk reaches high levels, the role of the risk factor in bicycle route choice becomes almost as important as the distance factor. Then, using segment-level data, a mixed logit model is developed to analyze the bicyclists’ facility preferences and capture the unobserved heterogeneity across the population. Effective sidewalk width, traffic signals, segment length, road functional class, street pavement condition, and one-way street configuration were found to be statistically significant. A bicycle path is demonstrated to be more attractive than a bicycle lane, based on the prediction analysis.^ Bicycle-pedestrian interaction is investigated through pedestrian's point of view. Using a sample of 114 respondents, pedestrian perceptions of level of service (LOS) on sidewalks shared with bicycles under various urban-street conditions are investigated. By estimating a random parameters ordered probit model of respondents' LOS assessments, we found, as expected, that pedestrian perceptions of LOS are strongly influenced by the pedestrian flow rate. However, bicycle influences such as bicycle flow rate, the speed of bicyclists, and several other factors were found to also significantly affect LOS perceptions. ^ Finally, 2,947 vehicle-related bicycle crash injury severities that occurred between 2003 and 2005 in Indiana are analyzed using a random parameters ordered probit model, which takes spatial heterogeneity into account. Bicyclist and driver characteristics, roadway, location, and collision characteristics are found to significantly influence bicyclist injury severity. The analytical tools and practical procedure developed in this study can be used to guide bicycle facility planning and assess bicycle risk and LOS factors.^

]]> Lei Kang Engineering, Civil|Transportation http://docs.lib.purdue.edu/dissertations/AAI1535037 http://docs.lib.purdue.edu/dissertations/AAI1535037 Wed, 22 May 2013 15:45:21 PDT Purpose: The purpose of this study was three fold: 1) to estimate associations between demographic, social, and environmental factors and the frequency and duration of physical activity on trails among adult trail users from Massachusetts; 2) to estimate associations between demographic, social, and environmental factors and the odds of using a trail for recreation versus transportation purposes; and 3) to estimate associations between demographic, social, and environmental factors and the odds of reporting an increase in physical activity since first use of the trail by adult trail users. ^ Methods: The social ecological model was used as a conceptual framework for this study. Demographic, social, and environmental data were collected from a random sample of adult trail users at five different sites in Massachusetts during 2004 and 2005 using brief intercept surveys. Secondary data analyses were conducted to estimate associations between demographic, social, and environmental factors and physical activity on trails using logistic regression. Unadjusted, age adjusted and fully adjusted models, which controlled for age and other demographic factors, were estimated. ^ Results: Demographic, social, and environmental variables were associated with the three outcomes. Demographic variables such as age and education demonstrated positive associations with frequency and duration of trail use and with the likelihood of using the trail for recreation/exercise versus transportation. Blacks/African Americans had an increased odds of using the trail for recreation/exercise in comparison to Whites. Use of a trail with family or friends was positively associated with duration of trail visits for recreation/exercise. About 59% of trail users reported an increase in their physical activity since first use of trail. Among environmental factors, trail design, trail safety, and good surface were associated with an increased likelihood of using the trail for recreation/exercise. ^ Conclusion: A combination of demographic, social and environmental factors were associated with the volume of physical activity on trails (i.e, frequency and duration of visits), the purpose of trail use (i.e, recreation versus transportation), and with reported increases in physical activity since first using the trail. These findings contribute to the growing public health literature on trails and physical activity. Additionally, these findings support the use of an ecological framework to examine influences on trail use. Finally, findings such as those presented in this thesis could be used to design more effective interventions to promote trail use in adult populations and thereby help adults meet physical activity recommendations.^

]]> Sayali V Kale Health Sciences, Public Health http://docs.lib.purdue.edu/dissertations/AAI1535036 http://docs.lib.purdue.edu/dissertations/AAI1535036 Wed, 22 May 2013 15:45:20 PDT Fossils are the key to dating the past, but geoscience students are rarely exposed to their use in constraining geologic time and deciphering regional sediment history. A software package and an associated student exercise that uses real data sets of fossils and sediment trends from drill sites in the Gulf of Mexico is developed to illustrate the application of biostratigraphy to understand regional depositional history and sea-level variations. ^ TimeScaleCreator Crossplot, a visualization system to understand the depth-to-age conversion methodology for converting well datasets varying in depth to geologic timescale was developed and tested. A transect consisting of four offshore wells and two onshore wells spanning Miocene and Oligocene epochs along an approximate linear trend was chosen to illustrate the concepts of sea-level variations. Depth-to-age conversion routine enables the students to convert the accompanying sediment facies to geologic timescale by comparing the fossil assemblages observed in the well to the biostratigraphy of Gulf of Mexico. After creating a transect from depth-to-age converted wells, students can identify depositional episodes of sand-dominated influxes separated by shale-deposition. The interplay between various sand and shale sequences allows the students to interpret sea-level variations in the northern Gulf of Mexico basin. ^ The student exercise developed consists of an introduction to biostratigraphy, depositional history in the Gulf of Mexico basin and a manual on how to use the visualization tool, which serves as background material to convert the wells from depth-to-age and interpret for sea-level variations. The student exercise is tested with undergraduate students and evidence of student learning is discussed. The student exercise also contains a teacher's manual that provides our suggested solutions.^

]]> Sribharath M Kainkaryam Geology http://docs.lib.purdue.edu/dissertations/AAI1535035 http://docs.lib.purdue.edu/dissertations/AAI1535035 Wed, 22 May 2013 15:45:19 PDT The Susan G. Komen for the Cure Virtual Tissue Bank application was evaluated for usability via established usability testing methods. Five subjects were each asked to perform five application tasks; the usability metrics gathered include time-on-task, task success, and issues with severity ratings. First, the study revealed that the application should provide better guidance when users are required to launch external applications. Second, results indicated that the layout of hyperlinks to searchable experimental datasets was confusing and should be redesigned. Moreover, the study showed that some subjects who were unsuccessful at completing certain tasks mistakenly believed they were successful. This indicated that the feedback delivered to the user by the application needed to be designed to remove ambiguities. Third, the author speculates that the descriptive power of the System Usability Scale may be tailored to fit data-driven bioinformatics repositories through exploratory factor analysis. The study demonstrated the relevance and need for usability research in the bioinformatics domain.^

]]> Eric Juhn Information Technology|Biology, Bioinformatics http://docs.lib.purdue.edu/dissertations/AAI1535034 http://docs.lib.purdue.edu/dissertations/AAI1535034 Wed, 22 May 2013 15:45:18 PDT A family business is comprised of two or more interlinking systems that determine its performance (McCollum, 1988). Using a sample of 632 small family businesses, this thesis investigated the relationship between conflict factors (family, interrole, work, and couple) to the proposed proxy of balance between the family and the business: a family business agreement. A variable that had a positive impact on a family business agreement was total experience of the business owner. Further, three variables increased the probability of having a family business agreement: separation of family and family business, perception that family comes first, and conflict that arises when decisions are in favor of the family versus the family business. The variable that had a negative impact on a family business agreement was division of ownership. Moreover, tension due to unresolved conflict decreased the probability of having a family business agreement.^

]]> Nicole Elyse Jones Economics, Agricultural http://docs.lib.purdue.edu/dissertations/AAI1535032 http://docs.lib.purdue.edu/dissertations/AAI1535032 Wed, 22 May 2013 15:45:17 PDT Scientists face an unprecedented challenge of increasing food production by 100% within the next fifty years to meet demand while responding to the undetermined effect and impact of climate change. To respond to these challenges, scientists are turning to models to assist them in mapping out the complex interactions between environmental conditions, management strategies and crop genotype. The Hybrid-Maize (HM) model is a process-based model that predicts maize growth, grain yields and stover in rainfed or irrigated conditions. The HM model has been widely used to predict yield potential in diverse locations such as Indonesia, Vietnam, China and the United States. The overall goals of this study are to evaluate HM model in the wet, rainfed conditions representative of northern Indiana and compare its performance to Crop Environment Resource Synthesis-Maize (CERES-Maize) model available in the Decision Support System for Agrotechnology Transfer (DSSAT) program. The specific objectives were to: 1) model performance for simulating early growth, stover and grain yield; 2) quantify the impact of excess water stress and grain filling temperatures on gaps between predicted and actual yields; and 3) compare HM and DSSAT CERES-Maize (DSSAT-M) under optimal conditions predictions to grain yield contest winners in Indiana. Weather, soil and management inputs were carefully gathered to ensure accuracy in model input data. Predicted growth, yield and stover were compared against the measured data collected at Purdue's Agronomy Center of Research and Education (ACRE). The HM model was found to be a good predictor of grain yield (n-RMSE=18%), a fair predictor of stover biomass (n-RMSE=23%) but it significantly over-predicted early growth (RMSE=1.19 Mg dry matter ha^-1). In contrast, DSSAT-M was found to be a good predictor of grain yield (n-RMSE=18%) and an excellent predictor of stover yield (n-RMSE=9%) and early growth (RMSE=0.31 Mg dry matter ha^-1). Excess water stress was significantly correlated to gaps in biomass predictions for HM at growth (V6) and stover growth stages. However, overall excess water stress was not correlated with grain yield gaps for both models. Both HM and DSSAT-M grain simulated yields were significantly correlated with average grain filling temperatures. Years experiencing relatively colder grain filling temperatures had larger yield gaps. Lastly, HM was a better predictor of regional yields from commercial contests than DSSAT-M. In conclusion, HM is a good predictor of grain yield and yield potential, DSSAT-M a good predictor of early growth biomass, stover and grain yield. Future research directions include: 1) adjusting the temperature based empirical equations used in predicting grain yield by to take into account cooler weather conditions during grain fill for both models, 2) expanding HM water stress function to include excess water stress and 3) Identifying the management, environmental and genotype factors involved in current contest winner grain yield tends in Indiana as compared to Nebraska contest winner grain yield trends.^

]]> Salah F Issa Agriculture, Agronomy|Agriculture, General http://docs.lib.purdue.edu/dissertations/AAI1535033 http://docs.lib.purdue.edu/dissertations/AAI1535033 Wed, 22 May 2013 15:45:17 PDT Continuous Descent Approach (CDA), which is among the key concepts of the Next Generation Air Transportation System (NextGen), is a fuel economical procedure, but requires increased separation to accommodate spacing uncertainties among arriving aircraft. Such negative impact is often overlooked when benefits are estimated. Although a considerable number of researches have been devoted to the estimation of potential fuel saving of CDA, few have attempted to explain the fuel saving observed in field tests from an analytical point of view. This research gives insights into the reasons why CDA saves fuel, and a number of design guidelines for CDA procedures are derived. The analytical relationship between speed, altitude, and time-cumulative fuel consumption is derived based on Base of Aircraft Data (BADA) Total Energy Model. Theoretical analysis implies that speed profile has an impact as substantial as, if not more than, vertical profile on the fuel consumption in the terminal area. In addition, CDA is not intrinsically a fuel-saving procedure: whether CDA saves fuel or not is contingent upon whether the speed profile is properly designed or not. Based on this model, the potential fuel savings due to CDA at San Francisco International Airport were estimated, and the accuracy of this estimation is analyzed. Possible uncertainties in this fuel estimation primarily resulted from the modeled CDA procedure and the inaccuracy of BADA. This thesis also investigates the fuel savings due to CDAs under high traffic conditions, counting not only the savings benefiting from optimal vertical profiles but also the extra fuel burn resulting from the increased separations. The simulated CDAs traffic is based on radar track data, and deconflicted by a scheduling algorithm that targets minimized delays. The delays are absorbed by speed change and path stretching, accounting for the air traffic controls that are entailed by CDAs. The fuel burn statistics calculated based on the BADA Total Energy Model reveals that the CDAs save on average 171.87 kg per arrival, but the number is discounted by delay absorption. The savings diminish as the arrival demand increases, and could be even negative due to large delays. The throughput analysis demonstrated that the impact of CDA on airport capacity is insignificant and tolerable. The Atlanta International Airport was used as the testbed for sensitivity analysis, and the New York Metroplex was used as the test bed for throughput analysis.^

]]> Li Jin Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI1535031 http://docs.lib.purdue.edu/dissertations/AAI1535031 Wed, 22 May 2013 15:45:16 PDT The primary goal of this study is to evaluate the effects of different media-based learning environments (MLEs) that present identical chemistry content material. This is done with four different MLEs that utilize some or all components of a chemistry-based media-based prototype video game. Examination of general chemistry student volunteers purposefully randomized to one of four different MLEs did not provide evidence that the higher the level of interactivity resulted in a more effective MLE for the chemistry content. Data suggested that the cognitive load to play the chemistry-based video game may impaired the chemistry content being presented and recalled by the students while the students watching the movie of the chemistry-based video game were able to recall the chemistry content more efficiently. Further studies in this area need to address the overall cognitive load of the different MLEs to potentially better determine what the most effective MLE may be for this chemistry content.^

]]> Dustin S Hillman Chemistry, General|Education, Sciences http://docs.lib.purdue.edu/dissertations/AAI1535030 http://docs.lib.purdue.edu/dissertations/AAI1535030 Wed, 22 May 2013 15:45:15 PDT Modeling is an effective tool for developing estimates of ecosystem dynamics in space and time, and for testing various hypotheses which are otherwise difficult to test under real experimental settings. Literature, field measurements and calibration are three major sources used to achieve model parameterization. Calibration, as one of the major model-data-fusion techniques, is widely used in ecosystem modeling. During the calibration process, field observations are used to constrain the rate limiting parameters in models. Therefore, how experimental data are used in the calibration process has a direct impact on modeling results and may potentially influence extrapolations of carbon cycling. In this study, we present a synthesis example of several options for the use of experimental data in modeling and explore the implications of those options. We calibrated the Terrestrial Ecosystem Model (TEM) on a hierarchy of three vegetation classifications levels for the Alaskan boreal forest: species-level, plant-functional-types-level (PFT-level) and biome-level, and we examined the differences in simulated carbon (C) cycling. The three levels of calibration all based on the same species-level observations while in PFT- and biome-level, the species-level observations are area-weighted to generate the synthesized observations for PFT-level and biome-level calibrations. We found that species-level and PFT-level simulations produced similar estimates of C fluxes and pools, whereas biome-level simulations consistently produced the lowest estimates, resulting in about 2.6 g C m^-2 yr ^-1 cumulative C difference in net ecosystem production from 1922 to 2099. This indicates that PFT-level simulations may be potentially representative of the performance of species-level simulations while biome-level modeling may produce more biased results. Our results suggest that the three options for using experimental data could result in different estimates of ecosystem C dynamics. Improved theoretical and empirical justifications for grouping species into PFTs or biomes is needed to properly represent the dynamics of ecosystem function and structure (e.g. the effects of fire-prone species and subsequent changes in successional trajectories and vegetation composition). Future studies should focus on better identification of species-specific functional characteristics to more appropriately classify species into PFTs for ecosystem model simulations.^

]]> Yujie He Biogeochemistry|Environmental Sciences http://docs.lib.purdue.edu/dissertations/AAI1535022 http://docs.lib.purdue.edu/dissertations/AAI1535022 Wed, 22 May 2013 15:45:15 PDT This thesis examines how differing types of training can improve children's learning from a video. Using the Preferential Looking Paradigm, we tested the effects of social (i.e., eye gaze and an animated character) versus attentional (i.e., audio-visual synchrony without a social interaction) components in the importance of remembering story elements. Specifically, children learned associations between shapes and containers (e.g., star in a house) from a video and were then tested on remembering these pairings immediately following the training phase and after a short break. Younger children (30-month-olds) showed better memory for pairings from the social training condition both before and after a break, while older children (36-month-olds) were inconsistent in their performance, despite better knowledge for the names for the shapes. Overall, these findings suggest that social cues play an important role in children's learning, especially at 30-months.^

]]> Arum Han Psychology, Developmental http://docs.lib.purdue.edu/dissertations/AAI1535021 http://docs.lib.purdue.edu/dissertations/AAI1535021 Wed, 22 May 2013 15:45:14 PDT The purpose of this study is to examine the relationship between phonological awareness and working memory in the development of basic reading skills in bilingual children. Tasks measuring phonological awareness, working memory, and word recognition were given to sixteen Spanish-English bilingual participants between the ages of 6 and 7 and who were currently enrolled in the first grade. This investigation features a correlation research method intended to determine the relationship between phonological awareness, working memory, and reading skills. Additionally, a multiple regression statistical procedure was applied to determine the extent to which phonological awareness and working memory predict reading both within and across languages. Results indicated that phonological awareness measurements in one language are associated with literacy outcomes in the other, but cross-linguistic transfer between English and Spanish reading measures decreased after controlling for working memory. This indicates that additional factors, such as working memory, play a role in explaining the cross-linguistic transfer of phonological awareness. These results are discussed in light of current research on bilingualism and point to the importance of reading as a shared ability between the two languages. ^

]]> Karina Leslie Hanson Education, Bilingual and Multicultural|Language, Linguistics http://docs.lib.purdue.edu/dissertations/AAI1535019 http://docs.lib.purdue.edu/dissertations/AAI1535019 Wed, 22 May 2013 15:45:13 PDT The resistance to women at the front of a church is often couched in theological or exegetical language, but I believe that this resistance is rooted in affect, and expressed emotively. For many, the reaction to a woman preaching a sermon or consecrating bread and wine is not about that woman, but about the intellectual and emotional baggage that does not permit a woman to inhabit that role. The vehement and visceral reactions against women in positions of ordained ministry are results of this affective response, and the nature of such a response means that rational or logical arguments are unlikely to be productive in changing the minds of those opposing or supporting women's ordination. Rather, I posit, the way forward in understanding and acting on this issue is through relationships and through the many stories of women who have traveled on this journey. My considerations of the roles of materiality and affect in women's ordination are centered on The Episcopal Church, a mainline denomination in the United States.^

]]> Alissa M Goudswaard Religion, General|Women's Studies|Language, Rhetoric and Composition http://docs.lib.purdue.edu/dissertations/AAI1535020 http://docs.lib.purdue.edu/dissertations/AAI1535020 Wed, 22 May 2013 15:45:13 PDT This study sought to integrate research on procrastination, rumination, and emotions into a single experiential flow under the umbrella of "the experience of procrastination." It examines the sensation of procrastination, negative emotions, and rumination over time. Specifically, it looks at the possible relationship between a task, the negative emotions it engenders (including guilt and shame specifically), ruminative thoughts about the task, and subsequent procrastination on the task. College students were surveyed multiple times during the course of a single writing assignment to examine changes in these variables. Some expected correlations were detected, including a relationship between negative emotions and rumination and correlations between rumination and procrastination. However, hypotheses regarding rumination predicting procrastination were not supported. Individuals who completed the assignment early (non-procrastinators) were compared to the remaining participants on several variables. The findings and their implications are discussed in detail.^

]]> Brett W Guidry Psychology, Developmental|Psychology, General http://docs.lib.purdue.edu/dissertations/AAI1535018 http://docs.lib.purdue.edu/dissertations/AAI1535018 Wed, 22 May 2013 15:45:12 PDT Nonlinear phenomena based resonating devices offer a very promising role as efficient and accurate MEMS devices in a rapidly growing and improving area of MEMS based sensing and actuation. The requirement of high reliability and accuracy stipulates very strict performance metrics of these devices. In order to understand the effects of any input variability on the output, a robust modeling and simulation technique should be developed which predicts the device behavior sufficiently accurately, while at the same time considering the computational complexity associated with complete nonlinear analytical modeling. ^ This works deals with a nonlinear T-shaped 1:2 internal resonance autoparametric resonator and looks into the uncertainty quantification aspect of it. The aleatoric uncertainties of material and geometric properties are considered and their quantification problem is addressed. The solution of the system, which is a two stepped process considering linear modeshapes and frequencies and nonlinear averaged Lagrangian, is modified for piezoelectric actuation. Simulation for uncertainties is done for the linear and nonlinear parts separately and effects of parameter variation on the final output are brought out. Several techniques of efficient simulation are presented and sensitivity of the device towards tuning is established. An attempt of experimental uncertainty quantification is presented with a macro-scale model built to replicate the functionality of the MEMS device. Various issues related to its operation in the macro domain are brought out and suggestions for further improvements are made based on the current observations. Future research on developing the MEMS device for characterization and uncertainty studies is suggested.^

]]> Rajat Goyal Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1535016 http://docs.lib.purdue.edu/dissertations/AAI1535016 Wed, 22 May 2013 15:45:11 PDT Dairy producers throughout the US continue to struggle with economic and social changes. Many of these producers are turning to pasture-based production systems which have significantly distinctive cost, revenue and management challenges. These differences cause some graziers to question whether the US Lifetime Net Merit (NM$) index which is based mainly on records from conventional herds, adequately facilitates selection of bulls to enhance pasture-based breeding programs. The gathering of data and subsequent development of indexes more closely aligned to pasture-based preferences and economic values attempts to answer this question. ^ A survey aimed at gathering information on genetic preferences, selection criteria, production methods, feeding and cow health was developed and distributed to producers in 23 states. Questions regarding herd and production history, breed utilization, and breeding practices were included. Graziers were also asked to rank genetic traits on a Leikert-like scale of negative 5 to positive 5 to indicate their preferences for various selection criteria. Respondents averaged 18.8 ± 18.6 years of grazing history, 133.4 ± 129.7 milking head, and grazed 232.5 ± 61.1 d per year. Production was 21.3 ± 5.1 kg of milk per cow per day, 4.0 ± 0.4% milk fat, and 3.3 ± 0.3% milk protein. Also, 47.5% of producers practiced seasonal calving, defined as 75% of cattle calving in any 3 mo. window. Seventy percent of producers indicated the use of the Holstein breed, thus the indexes were created based upon Holstein characteristics. Two indexes were created using average ranks of traits in a grazing environment. Grazing preference index 1(GP1) weights were the relative ranking of each trait. Grazing preference index 2 (GP2) weights were created using a desired gains approach. GP1 was strongly correlated with Net Merit $ (NM$) (r=0.95), while GP2 was less strongly correlated with NM$ (r=0.56). Despite high correlations with previously existing indexes, producer desires are not being fully addressed, thus suggesting that there may be a benefit in an index specific to graziers' needs. ^ The results of the survey were combined with economic data from the literature to develop three grazing merit indexes (GM$1, GM$2, and GM$3), which were compared to current US indexes. The two indexes differed only in that GM$1 utilized a milk price based on average prices from the previous five years while GM$2 utilized milk price based on the NM$ and essentially restricted to no gain in milk volume. GM$3 utilized cull prices and interest rates based on NM$. The economic weights of the traits for GM$ were multiplied by the predicted transmitting abilities 584 active artificial insemination Holstein bulls to compare with NM$. Spearman rank correlations for NM$ were 0.93 (p <.0001) with GM$1, 0.98 (p<.0001) with GM$2 and 0.98 (p<.0001) with GM$3. Traits included (and their percentage of weight) in GM$1 and GM$2 respectively include: Milk Volume (24%, 0%, 0%), Fat Yield (16%, 21%, 21%), Protein Yield (4%, 17%, 17%), Productive Life (7%, 8%, 7%), Somatic Cell Count (-8%, -9%, -9%), Feet and Leg Composite (4%, 4%, 4%), Body Size Composite (-3%, -4%, -4%), Udder Composite (7%, 8%, 8%), Daughter Pregnancy Rate (18%, 20%, 8%), Calving Ability (3%, 3%, 3%), and Dairy Form (6%, 6%, 6%). This is compared to NM$ 0, 19, 16, 22, 10, 4, 6, 7, 11, 5, and 0 % for the same traits, respectively. Dairy Form was added to GM$ to offset the decrease in strength associated with selection to reduce stature through selection against a Body Size Composite. The large increase in the relative importance of Milk Volume in GM$1, was due to a difference in the milk prices used to calculate the index and the increased marginal value of milk yield because production is less in grazing systems. The substantial increase in the index weight on Daughter Pregnancy Rate in GM$ compared to NM$ reflects the increased focus on seasonal calving in grazing herds. Emphasis on Productive Life decreased substantially in GM$ because grazing cattle have been estimated to remain in the herd longer, therefore the marginal value of increasing length of Productive Life is diminished. While NM$ provides guidance for pasture-based dairy producers, a GM$ index based upon appropriate costs and revenues, will allow selection of cows and bulls to allow more optimal genetic progress.^

]]> Keegan D Gay Agriculture, Animal Culture and Nutrition http://docs.lib.purdue.edu/dissertations/AAI1535017 http://docs.lib.purdue.edu/dissertations/AAI1535017 Wed, 22 May 2013 15:45:11 PDT Supersonic flight over inhabited territories of the United States has been banned by the Federal Aviation Association since 1973. While research has been conducted to determine the effects of sonic booms on the general population when heard outdoors, little work has been done on people's perception of sonic booms as heard indoors. A technique to simulate indoor sounds from an outdoor sound has been developed. Using this, subjective tests have been done to determine the best way to use this simulation (i.e. whether diotic or dichotic sounds should be used) and to determine which indoor room characteristics, if any, have an effect on the population's perception of annoyance when hearing sonic booms indoors. Two annoyance models based on sound metrics proposed by Marshall and Davies have also been explored, and it was observed that while these two models were proposed for outdoor sounds, they are also quite accurate in predicting annoyance to sonic booms when heard indoors.^

]]> Clothilde Giacomoni Engineering, Aerospace|Physics, Acoustics http://docs.lib.purdue.edu/dissertations/AAI1535015 http://docs.lib.purdue.edu/dissertations/AAI1535015 Wed, 22 May 2013 15:45:10 PDT Applications of fiber filled thermoplastic injection molded parts are increasing. The need to predict and quantify the variability in these parts grows with the demand. In this work variability of the fiber orientation is captured through the Folgar-Tucker orientation tensor and variability in anisotropy is captured through the ratio of the first two diagonal terms of the fully anisotropic stiffness matrix. The largest influences on the variability of these two parameters are determined to be the mold temperature, the melt temperature, and the temperature of the heater rods in the mold. Models to predict the response of the parameters over a range of input variability are developed. ^

]]> Jessie Trece Garrett Engineering, Aerospace|Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI1535014 http://docs.lib.purdue.edu/dissertations/AAI1535014 Wed, 22 May 2013 15:45:09 PDT Boutique and lifestyle hotels (BLH) have relied on their experiential nature to differentiate themselves in a competitive market place. The present exploratory study is intended to clarify boutique and lifestyle hotel manager perceptions regarding the creation of the boutique/lifestyle hotel experience as a business strategy. This exploratory analysis utilized a framework of customer service and constructs of the experience economy model. The empirical segment included website-based surveys of a total of thirty-eight boutique and lifestyle hotel general managers, owners, and other operations and corporate managers. To understand the boutique/lifestyle hotel experience, the researchers examined manager perceptions concerning the importance of the customer experience, physical environment and customer service environment, three elements of experience differentiation, and intended behavioral responses. The researchers applied analysis of variance (ANOVA) and the Pearson product-moment correlation coefficient for data analysis. Results showed that the customer service environment played a prominent role in design and management elements, differentiation in customer service environment was the chief approach, and a customer experience that focused on esthetics was the ideal boutique and lifestyle hotel experience. Overall, the findings explained the importance of environment stimuli to the boutique and lifestyle hotel experience, provided insight into the experiential nature of a BLH and offered notable implications for hotel marketers.^

]]> Lilu Gao Business Administration, Marketing|Business Administration, Management|Recreation http://docs.lib.purdue.edu/dissertations/AAI1535012 http://docs.lib.purdue.edu/dissertations/AAI1535012 Wed, 22 May 2013 15:45:08 PDT Oral repeated reading, which was proposed based on automaticity theory (LaBerge and Samuels, 1974), has been widely used with struggling first language (L1) English readers. Studies show that it is effective in improving reading rate and comprehension on practiced passages and that the effect was transferred to unpracticed passages (Dowhower, 1987; Herman, 1985). However, there is little such research on the second language (L2) readers (Taguchi,1997; Taguchi & Gorsuch, 2002; Taguchi, Takayasu-Mass, & Gorsuch, 2004; Taguchi and Gorsuch, 2008; Blum, Koskinen, Tennant, Parker, Straub and Curry,1995); moreover, no study has investigated the effect of this method for Japanese as second or foreign language readers yet. However, due to the uniqueness of the Japanese writing system, it is speculated that L2 Japanese learners will need more practice in letter-decoding skills. Thus, this method, which intends to increase the automaticity of letter-decoding, may be effective for learners of Japanese as a second/foreign language. ^ The present study examines the effect of oral repeated reading on reading rate, comprehension, and the number of wrong pauses of novice-high to intermediate-low level learners of Japanese as a foreign language for practiced and unpracticed passages. Twenty-seven students who were enrolled in JPNS 202 in fall 2012 at a Midwestern university were assigned to one experimental and one control group. Both groups recorded their readings and answered comprehension questions as pre- and post-tests for five practiced passages and one unpracticed passage. Only the experimental group received oral repeated reading training as online homework for five practiced passages between the pre-and post-tests. ^ The results indicate that both groups improved in all three factors (reading rate, comprehension, number of wrong pauses) on both practiced and unpracticed passages. However, on the practiced passage, the improvement was more significant in the experimental group than the control group on all the factors. The experimental group showed a partial transfer effect for the reading rate, with more significant transfer effect for the reduction of wrong pauses. On the other hand, the transfer effect on comprehension was not as significant as the other factors. It is concluded that this method was an effective way to improve the three factors: reading rate, comprehension, and reduction of wrong pauses on both types of passages: practiced and unpracticed passages, though the degree of transfer varied with the more significant effect for the reduction of wrong pauses.^

]]> Eriko Fujita Education, Foreign Language|Language, General http://docs.lib.purdue.edu/dissertations/AAI1535013 http://docs.lib.purdue.edu/dissertations/AAI1535013 Wed, 22 May 2013 15:45:08 PDT In recent years, China's prosperous economy and large consumer market have attracted investment from Chinese and American hotel companies. During this time Chinese consumers have become increasingly sophisticated in their expectations of hotel services and interested in sharing their experiences and opinions on Internet. The present study explores Chinese consumers' different perceptions between Chinese and American branded hotels, by examining 200 online consumer reviews pertaining to 20 four-star and higher level Chinese and American branded hotels in Shanghai and Beijing. All data is analyzed by qualitative content analysis method for comprehensive interpretation of Chinese consumers' perceptions. Online feedback behaviors of Chinese consumers and differences between hotels in Shanghai and Beijing are discussed as well. Suggestions for Chinese and International hotel companies are proposed.^

]]> Wenjing Gao Business Administration, Marketing|Sociology, Theory and Methods|Information Science|Recreation http://docs.lib.purdue.edu/dissertations/AAI1535011 http://docs.lib.purdue.edu/dissertations/AAI1535011 Wed, 22 May 2013 15:45:07 PDT With feed costs accounting for the greatest expense on a dairy farm, producers are constantly on the lookout for alternate feeds and additives that can be utilized in the diets of lactating cows at economically beneficial levels. To more closely evaluate practical feeding applications and their resulting effects on production and efficiency, two studies were conducted. The objective of Study 1 was to determine the effect of sudden additions of condensed distillers solubles (CDS) on milk production, milk components, and rumen measures of lactating dairy cows. Study 1 utilized 8 ruminally cannulated Holstein cows (166 ± 12 DIM) that were randomly assigned to treatments in a replicated 4 x 4 Latin square design with 21−d periods. Cows were fed control (CON) diets for a 14−d adaptation period and 1 of 4 treatment diets for a 7−d period with the last 3 d used for data collection. The treatment diets were CON, a diet containing 20% DDGS (DDGS), a diet with 2.5% CDS (CDS2.5), and a diet with 5.0% CDS (CDS5) on a DM basis. Milk samples were collected daily to determine milk components. Rumen samples were collected via rumen cannulas for determination of pH, volatile fatty acids (VFA) and NH₃. Milk yield and fat percentage were similar between treatments, while cows fed the CON diet had greater, and DDGS tended to have, greater milk protein concentrations when compared with the CDS diets. Dry matter intake was greater for CON than CDS2.5 or CDS5 but was similar to DDGS. Rumen pH was lesser for CON than CDS5 and lesser for DDGS than either of the CDS diets. Rumen NH₃ was greater for CON and DDGS and tended to be greater for CDS2.5 than for CDS5. Sudden additions of up to 5% added CDS in dairy cow diets decreased milk protein concentration and DMI without affecting milk yield or milk fat. Study 2 further evaluated practical feeding applications available to producers. The objective of Study 2 was to evaluate the effect of potassium carbonate supplementation on water intake, rumen measures and production of lactating dairy cows. In this study, 0% (Control), 0.75% (LowK), or 1.5% (HighK) potassium carbonate, on a DM basis, was added to the diets of 9 ruminally cannulated, late lactation Holstein cows (207 ± 12 DIM) that were randomly assigned to treatments in a replicated 3 x 3 Latin square design with 18−d periods with the last 4 d used for data collection. Milk yield was determined and milk samples were collected twice daily and analyzed for milk composition. Total rumen evacuations were conducted to determine total rumen digesta weight and DM, with rumen samples collected to determine VFA and NH₃ concentrations as well as rumen pH. Milk, milk fat and protein yields showed quadratic responses with greatest yields for LowK. Dry matter intake had a quadratic response with cows on the LowK diet eating, on average, 1 kg/d more than either the CON or HighK diets. Water intake increased linearly as amount of K increased in the diet. Total and wet weight of rumen contents declined linearly and dry weight tended to decline linearly as K increased. Increasing dietary K in the diets of lactating dairy cows increased water consumption and rumen NH₃ concentrations, while decreasing total water weight in the rumen. Understanding the effect of specific feed ingredients on lactating dairy cow performance is essential for producers to effectively meet the nutritional needs of their animals. Both studies indicate potential applications for producers when utilizing various options for feeding dairy cattle.^

]]> Sarah Elizabeth Fraley Agriculture, Animal Culture and Nutrition http://docs.lib.purdue.edu/dissertations/AAI1535010 http://docs.lib.purdue.edu/dissertations/AAI1535010 Wed, 22 May 2013 15:45:06 PDT The overall goal of this thesis is to determine if improved operations technologies are economically viable for US airlines, and to determine the level of environmental benefits available from such technologies. Though these operational changes are being implemented primarily with the reduction of delay and improvement of throughput in mind, economic factors will drive the rate of airline adoption. In addition, the increased awareness of environmental impacts makes these effects an important aspect of decision-making. Understanding this relationship may help policymakers make decisions regarding implementation of these advanced technologies at airports, and help airlines determine appropriate levels of support to provide for these new technologies. In order to do so, the author models the behavior of a large, profit-seeking airline in response to the introduction of advanced equipage allowing improved operations procedures. The airline response included changes in deployed fleet, assignment of aircraft to routes, and acquisition of new aircraft. From these responses, changes in total fleet-level CO₂ emissions and airline profit were tallied. ^ As awareness of the environmental impact of aircraft emissions has grown, several agencies (ICAO, NASA) have moved to place goals for emissions reduction. NASA, in particular, has set goals for emissions reduction through several areas of aircraft technology. Among these are "Operational Improvements," technologies available in the short-term through avionics and airport system upgrades. ^ The studies in this thesis make use of the Fleet-Level Environmental Evaluation Tool (FLEET), a simulation tool developed by Purdue University in support of a NASA-sponsored research effort. This tool models the behavior of a large, profit-seeking airline through an allocation problem. The problem is contained within a systems dynamics type approach that allows feedback between passenger demand, ticket price, and the airline fleet composition so that the demand and airline operations evolve over time. ^ The studies indicate that, despite an increased cost, improved equipage provides benefits to airline profits as long as equipped airports are available. Improved equipage also reduces fuel burn on a per-flight basis, but depending on the percentage of equipped aircraft in the fleet, the overall airline fuel burn may increase. Improved equipage does increase capacity at busy airports – such as Chicago O'Hare – allowing a greater number of aircraft to operate at the airport on any given day. A sensitivity study indicates that, in the FLEET model, airline profits are most sensitive to changes in the underlying demand for air travel, followed by the price of jet fuel. Equipage related factors, such as the number of equipped airports in the network or the cost of improved equipage, have a comparatively minor influence on airline profit. Of these secondary factors, the assumed decrease in trip or segment distance enabled by improved equipage systems has the greatest impact on profit. Ability to retrofit aircraft and entry-in-service date of equipped aircraft has the greatest impact on the number of equipped aircraft in the fleet.^

]]> Ryan Patrick Foley Engineering, Aerospace|Engineering, Environmental http://docs.lib.purdue.edu/dissertations/AAI1535009 http://docs.lib.purdue.edu/dissertations/AAI1535009 Wed, 22 May 2013 15:45:06 PDT This thesis is oriented toward developers, owners, operators and investors of renewable energy projects. With increasing demand of renewables, our energy dependence comes down to reducing costs associated with this sector so as to compete with the existing sources. One way of valuing investment potential is to determine and then compare the overall value derived by investing in a particular project. Several engineering and financial levers, one of which is operation and maintenance, affect this value. ^ This thesis provides a useful visual aid to owners and operators by which they can operate and maintain their wind farm so as to achieve maximum value throughout its lifetime. All the necessary components that go into developing a business model of a wind farm project will be discussed. Finally, this tool is valid within the assumptions that are explicitly stated. Real world data and trends are used to provide a practical approach to the optimization.^

]]> Kevin Fernandes Alternative Energy|Engineering, Aerospace|Engineering, Electronics and Electrical|Engineering, Industrial|Energy http://docs.lib.purdue.edu/dissertations/AAI1535008 http://docs.lib.purdue.edu/dissertations/AAI1535008 Wed, 22 May 2013 15:45:05 PDT In digital wireless communication systems, the development of computationally intensive blocks not only increases functionality and improves quality but also leads to more power consumption. Many studies have been done to show how to make trade-offs between energy (supply voltage scaling) and quality for a single DSP (Digital Signal Processing) block. However, within a digital communication system, there is more than one DSP block. For example, in an OFDM (Orthogonal Frequency Division Multiplexing) system, the two most computationally intensive blocks are IFFT (Inverse Fast Fourier Transform) and FFT (Fast Fourier Transform). If the supply voltage of IFFT is over-scaled to achieve lower power consumption, leading to some approximation in the IFFT block, the parameters of FFT should also be adjusted to achieve the best match for the approximated IFFT. Hence, it is clear that there is a need to build a cross layer design framework to achieve optimized energy and quality trade-offs for the system as a whole under supply voltage over-scaling. In this thesis, we propose a new design framework for digital wireless communication systems, which can achieve an energy-quality efficient system under given channel condition by appropriate scaling of supply voltage.^

]]> Deliang Fan Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI1534995 http://docs.lib.purdue.edu/dissertations/AAI1534995 Wed, 22 May 2013 15:45:04 PDT Previous research has shown that dietary variety augments energy intake over a single meal, and possibly over the longer term. The aims of this study were to examine dietary variety consumed by US adults in recent years and the relationships of six types of dietary variety with BMI and micronutrient intakes. Analyses were conducted on one day of dietary data, including adults 21-60 years from the National Health and Nutrition Examination Survey 2003-04 and 2005-06 who were not pregnant or lactating, had a BMI of 18.5 to 100, and were not missing dietary recall information. The total sample and a subsample of biologically plausible dietary reporters were analyzed. In the total sample MyPlate variety and energy-weak variety were inversely related to BMI, while MyPlate and energy-dense variety were positively related to BMI for plausible reporters. High energy-weak variety reduced the odds of overweight or obesity in the total and plausible samples. In only the plausible sample, MyPlate, micronutrient-dense, and energy-dense variety increased the odds. All variety scores were positively associated with micronutrient intakes (mean%EAR) for 15 micronutrients in the total sample and remained positive, although attenuated, for MyPlate, energy-dense and micronutrient-dense variety. In the total sample all variety types reduced the odds for not meeting the EAR, in the plausible sample; energy-dense variety, MyPlate, and micronutrient-dense variety reduced these odds. Based on the association with increased BMI, specific types of dietary variety should be studied experimentally for their potential causal role in the obesity epidemic separately from overall variety.^

]]> Rachel Eve Ebner Health Sciences, Nutrition|Health Sciences, Epidemiology http://docs.lib.purdue.edu/dissertations/AAI1534994 http://docs.lib.purdue.edu/dissertations/AAI1534994 Wed, 22 May 2013 15:45:03 PDT Settlement of the Midwest, with the subsequent conversion of tallgrass prairie to agricultural fields, has led to a drastic reduction of soil carbon (C). As agricultural fields are returned to grasslands, it is important to understand the factors influencing rates of C and nitrogen (N) accrual in order to better predict C storage rate and capacity. In this study, we first evaluated the effect of soil texture, plant productivity, species richness and C4 grass-legume complementarity on soil C and N. In addition, we used a chronosequence approach to estimate the rate of soil C and N accrual. Soil samples were collected at depths up to 90 cm from remnant prairies, high-diversity prairie restorations, medium and low-diversity plantings enrolled in the Conservation Reserve Program (CRP), and crop fields in Newton County, IN and Lee County, IL. Vegetation surveys and biomass collections were conducted in the prairie and conservation areas to estimate plant species richness, functional group abundance, and productivity. ^ We found that soil silt + clay content was the most important predictor for soil C and N content, in Newton and Lee Counties. Difference among field treatments fell along lines of soil texture, as fields with high silt + clay content were the first to be converted to agriculture due to their greater productivity compared to the sandy prairie remnants. As predicted, soil C and N increased with plant productivity. However, we found soil C and N decreased with species richness. There was no effect of legumes on soil C and N content in C4 grass dominated grasslands. ^ In our chronosequence study, soil C and N increased with time since restoration, however the pattern was not significant over the initial chronosequence when remnant prairies were excluded. After omitting remnant prairies, the relationship between C and time since restoration was strengthened when variance due to silt + clay content was accounted for in the Newton County MD and LD restorations and Lee County low silt + clay restoration chronosequence, through residual analysis. Standardized multiple linear regression (MLR) showed soil C and N increased with silt + clay content both counties, and decreased with species richness, particularly in Lee County. Standardized MLR showed C and N to increase with field age in Newton County, but decrease with field age in Lee County. This may be due to leaching of C and N because the oldest restorations were located in areas with greater slope and well-drained soils. Labile soil C decreased slightly with time since restoration in both Newton and Lee Counties.^

]]> Katherine M Duszynski Biology, Ecology|Agriculture, Soil Science|Agriculture, Range Management http://docs.lib.purdue.edu/dissertations/AAI1534993 http://docs.lib.purdue.edu/dissertations/AAI1534993 Wed, 22 May 2013 15:45:02 PDT We proposed and conducted a simulation study to investigate both the effect of residual stress and tool wear on the distribution of rolling contact fatigue life. Distributions of both crack initiation life and propagation life have been studied by introducing normally distributed randomness in residual stress. Simulation results show that lognormal distribution is the most suitable distribution to describe the distribution of rolling contact fatigue life assuming the residual stress follows a normal distribution. Results are validated by comparing the simulation results with previous rolling contact fatigue test results. The simulation results showed good agreement on lower maximum Hertzian stress area on the average value for fatigue life with previous experimental results. ^ Experimental investigation of the tool wear effect on rolling contact fatigue life has been performed on AISI 1045 steel. The fatigue lives for three levels of tool wear were investigated and compared. It has been shown experimentally that tool wear can introduce as large as 33 times of fatigue life differences between machined pieces. Comparison between predicted fatigue life and experimental fatigue life were investigated. However, due to the large variation in the experimental fatigue life results, we cannot make a firm conclusion on the accuracy of the predicted model.^

]]> Jing Ding Engineering, Industrial http://docs.lib.purdue.edu/dissertations/AAI1534992 http://docs.lib.purdue.edu/dissertations/AAI1534992 Wed, 22 May 2013 15:45:01 PDT Strict noise regulations at major airports and increasing environmental concerns have made prediction and attenuation of jet noise an active research topic. Large eddy simulation coupled with computational aeroacoustics has the potential to be a significant research tool for this problem. With the emergence of petascale computer clusters, it is now computationally feasible to include the nozzle geometry in jet noise simulations. In high Reynolds number experiments on jet noise, the turbulent boundary layer on the inner surface of the nozzle separates into a turbulent free shear layer. Inclusion of a nozzle with turbulent inlet conditions is necessary to simulate this phenomenon realistically. This will allow a reasonable comparison of numerically computed noise levels with the experimental results. Two viscous wall boundary conditions are implemented for modeling the nozzle walls. A characteristic-based approach is compared with a computationally cheaper, extrapolation-based formulation. In viscous flow over a circular cylinder under two different regimes, excellent agreement is observed between the results of the two approaches. The results agree reasonably well with reference experimental and numerical results. Both the boundary conditions are thus found to be appropriate, the extrapolation-based formulation having an edge with its low cost. This is followed with the crucial step of generation of a turbulent boundary layer inside the nozzle. A digital filter-based turbulent inflow condition, extended in a new way to non-uniform curvilinear grids is implemented to achieve this. A zero pressure gradient flat plate turbulent boundary layer is simulated at a high Reynolds number to show that the method is capable of producing sustained turbulence. The length of the adjustment region necessary for synthetic inlet turbulence to recover from modeling errors is estimated. A low Reynolds number jet simulation including a round nozzle geometry is performed and the method is found to be successful in producing a turbulent shear layer. Imposition of larger turbulent integral length scales at the inlet is found to be effective in achieving a quicker recovery of turbulent fluctuations at low Reynolds numbers.^

]]> Nitin S Dhamankar Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI1534990 http://docs.lib.purdue.edu/dissertations/AAI1534990 Wed, 22 May 2013 15:45:00 PDT This thesis researched the effects of environments, microphone spacing, and source variations on the blind sound source separation Degenerate Unmixing Estimation Technique (DUET). Sound analysis as a tool to monitor environments has become common in healthcare, consumer, and security industries. Monitoring sounds in an environment could also be applicable in the power industry to save electrical energy. The most common forms of sound analysis are sound identification and localization which use a variety of sound feature extraction and pattern recognition techniques. The most important and common problem for feature extraction in pattern recognition systems is the presence of noise from multiple sources. ^ Sound source separation offers an innovative solution to improve sound identification and localization systems. The DUET algorithm is a blind sound source separation algorithm developed for anechoic mixtures, but previous research has suggested that the DUET algorithm's performance in echoic environments should be studied. This thesis aimed to determine if the DUET algorithm is capable of detecting and separating multiple unknown sound sources in an echoic environment. ^ This research tested the DUET algorithm's performance for sound source detection and separation, to better understand the effects of the environment, microphone spacing, and source variations. The sample set consisted of two real and one clean environment, three microphone spacings, and fifteen sound source combinations. The data was collected using high quality professional grade recording equipment. Matlab was used to process the data and the researcher visually inspected all histograms and listened to all sound source estimations to analyze the DUET algorithm's performance. These results were finally assessed using a success rate percentage metric. Both the DUET algorithm's performance and the final results were analyzed for both physical and spatial sound sources. ^ This research confirms that both sound source detection and separation of multiple unknown sound sources in echoic environments is possible using the DUET algorithm; however, the environment, microphone spacing, and source variations all have impacts, usually negative, on the DUET algorithm's performance in echoic environments. The overall success rates were on average around 50% for both source detection and separation when only two spatial sources were present. Experiments with three or four sources showed success rates below 25%. This suggests that the DUET algorithm, without modification, is not effective for practical source detection or separation in echoic environments. While many problems exist when using the DUET algorithm in echoic environments for source detection and separation, solutions and other applications are possible using the algorithm.^

]]> Blair R Conner Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI1534991 http://docs.lib.purdue.edu/dissertations/AAI1534991 Wed, 22 May 2013 15:45:00 PDT Despite the increased focus on improving student retention and graduation rates in higher education and steady increases in the number of first-generation and low-income students enrolling in college, there continues to be a deficit in research focused on how social class relates to student success. Recognizing the important role of belonging and identity in student outcomes, this thesis aims to add to the growing body of research focused on exploring the experiences of lower-income and first-generation college students as they attend college. This project uses semi-structured interviews with six first-generation and lower-income college students at a large-Midwestern public institution to examine their experiences. Using Bourdieu's concepts of capital and habitus, I examine how students' experiences impact their sense of belonging. Then, applying the tenets of social identity theory, this thesis explores student identity as it relates to their experiences of belonging both at the university and at home. The results of this research are consistent with literature indicating that lower-income and first-generation college students face many barriers in their path to obtaining a college degree. And while findings indicate that these barriers can impact students' identities in negative ways, the results also indicate that students' develop strong positive identities associated with their lower-income, first-generation college student status as well. The results point to some important implications for practice, including the need for colleges and universities to focus on creating an institutional culture that is not only tolerant of diverse student experiences, but that also recognizes their experiences as valuable. These conclusions indicate the need for more research to continue to explore the complexity associated with first-generation and lower-income student identity and the way in which it develops.^

]]> Erin Lion DeRosa Education, Sociology of|Education, Higher http://docs.lib.purdue.edu/dissertations/AAI1534988 http://docs.lib.purdue.edu/dissertations/AAI1534988 Wed, 22 May 2013 15:44:59 PDT This study investigates children's influence in the selection of family dining-out options. To further understand the connection between children's influence on family dining-out consumption and practical behaviors, we studied children's role in relation to family communication patterns. Moreover, we tested items of different dining-out influence categories to confirm differing degrees of health and nutrition concerns between parents and children. Additionally, children's demographic characteristics were also examined as predictors influencing family dining-out choices. The empirical assessment of this research was cast in the context of family restaurants. Subjects for this study focused on Taiwanese family consumers. This study offers practical implications for owners of food-service facilities in the development of family-friendly menus and services and in the development of future marketing strategies.^

]]> Yang-Su Chen Business Administration, Marketing|Sociology, Individual and Family Studies http://docs.lib.purdue.edu/dissertations/AAI1534989 http://docs.lib.purdue.edu/dissertations/AAI1534989 Wed, 22 May 2013 15:44:59 PDT This study is to examine the accuracy of DVH data exported from the Gamma Knife treatment planning system (Leksell GammaPlan, LGP) to the external beam treatment planning system, Varian ECLIPSE version 10. Different sizes of target volume, ranging from approximately 0.5 cm³ to 30 cm³, were created in LGP and exported to ECLIPSE with different calculation grid sizes (0.6 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm). The relationships between the sizes of the target and the grid sizes were obtained by comparing the DVH data reviewed in ECLIPSE with the DVH calculated in LGP. A general DVH comparison method, gamma analysis, was used. The results indicated that dose grid resolution does not significantly influence DVHs of larger targets (> 5 cm³) . As the gamma criteria were set more strictly, gamma value became more sensitive to the grid size. There was a trend that the gamma analysis passing rate increased as the selected grid size decreased with the identical target and as the target size increased with the same grid size selected. To conclude, dose grid resolution, target size and the dose distribution around the edge of the target were the three principal factors which influenced the accuracy of LGP DVH data in the linear accelerator TPS. This study is not limited to LGP exporting to ECLIPSE, it can be applied to any TPS exporting to another TPS.^

]]> Jing-Ni Chen Health Sciences, Radiology http://docs.lib.purdue.edu/dissertations/AAI1534986 http://docs.lib.purdue.edu/dissertations/AAI1534986 Wed, 22 May 2013 15:44:58 PDT Electroslag remelted (ESR) ingots of INCOLOY alloys 800 and 825 are particularly prone to macroscale slag inclusions and microscale cleanliness issues. Formation of these structures near the ingot surface can cause significant production yield losses (∼10%) due to the necessity of extensive surface grinding. Slag inclusions from near the outer radius of the toe end of alloy 800 and 825 ingots were found to be approximately 1 to 3 mm in size and have a multiphase microstructure consisting of CaF₂, CaTiO₃, MgAl ₂O₄, MgO and some combination of Ca₁₂Al₁₄ O₃₂F₂ and/or Ca₁₂Al₁₄O ₃₃. These inclusions were often surrounded by fields of 1 to 10 μm cuboidal TiN particles. A large number of TiN cuboids were observed in the ESR electrode with similar size and morphology to those observed surrounding slag inclusions in the ESR ingots, suggesting that the TiN particles are relics from ESR electrode production process. Samples taken sequentially throughout the EAF-AOD processes showed that the TiN cuboidals that are found in ESR ingots form between tapping the AOD vessel into the AOD ladle and the casting of ESR electrodes. ^ Analysis of slag skin at various heights of alloy 825 ingots revealed that the phase fraction of CaF₂ decreased, whereas TiCaO ₃ and Ca₁₂Al₁₄O₃₂F₂ increased, from toe to head. The observed increase in TiO₂ content suggests that at most a two-fold increase in viscosity of the slag would be expected. Similar analysis of alloy 800 ingots did not reveal significant trends in slag skin composition, possibly due to differences in ingot geometry or the presence of Al toe additions during the remelting of alloy 800. Directional solidification experiments were conducted to determine the solidification sequences of two common ESR slags: Code 316 (33% CaF₂, 33% CaO, and 33% Al₂O₃) and Code 59 (50% CaF₂, 20% CaO, 22% Al₂O₃, 5% MgO, and 3% TiO₂). In both cases the changes in slag phase fraction as a function of solidification time were not as significant as predicted. This suggests substantial solute concentrations within each phase, significant gas phase reactions or insufficient imposed temperature gradient for directional planer solidification. Optical microscopy and SEM analysis revealed a dendritic structure with Ca₁₂ Al₁₄O₃₂F₂ as the primary phase and significant interdendritic porosity. EDS analysis showed that Al segregates to the primary phase while F segregates to the interdendritic regions. Parametric studies using a numerical model of ESR suggests that the ESR process is quite sensitive to changes in slag electrical conductivity and not very sensitive to changes in slag viscosity.^

]]> Jonathan D Busch Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI1534985 http://docs.lib.purdue.edu/dissertations/AAI1534985 Wed, 22 May 2013 15:44:57 PDT There is increasing consensus that regeneration of a variety of commercially and/or ecologically favored forest tree species benefits from maintaining partial canopy cover. American chestnut (Castanea dentata (Marsh.) Borkh.) was once an important element of North American eastern temperate forests before the introduction of a foreign pathogen decimated the population. A blight-resistant, backcross chestnut hybrid has been developed and chestnut reintroduction will occur in part using reforestation under partial canopy. In the first experiment (CHAPTER 2), American chestnut bareroot (1+0) seedlings from three orchard sources (orchards) were grown under one of three light availabilities (high, 76%; medium, 26%; and low, 8% full PAR) and subjected to one of two levels of water availability (well-water and water stressed induced mid-season). In the second study (CHAPTER 3), the effects of overstory and herbaceous root competition on growth and survival of American chestnut and northern red oak (Quercus rubra L.) seedlings planted following midstory removal (14% transmittance) over three years were examined; leaf physiological traits were measured on surviving American chestnut seedlings during the third year. ^ In the first experiment (CHAPTER 2), light availability and water stress interacted to affect many seeding physiological and morphological traits. Seedlings growing under medium and high light wilted at lower leaf Ψ _pd (144 and 150% respectively) than low light seedlings. Recovery of relative net photosynthesis (A_net) and stomatal conductance (g_s) over a 2-4 week recovery period was greater in low and medium light, A_net (160 and 164%, respectively) and g_s (162-181%, respectively), than in high light. Recovery of relative A_net and g_s was lower (53-62% and 43-62%, respectively) under high light for one orchard source than the other two, though most other orchard effects were non-significant. As light availability was reduced, light became limiting to the extent that adding an additional stress (in this case water stress) had no impact on a number of growth and morphological traits. ^ In the second experiment (CHAPTER 3), overstory root competition reduced the relative aboveground growth of both species (51-60%). Herbaceous root competition had no effect on seedling growth, yet reduced survival (81%) in northern red oak. American chestnut showed greater net photosynthetic assimilation (8%), stomatal conductance (13%), and leaf N concentration (4%) in the absence of overstory root competition. American chestnut had greater relative aboveground growth compared to northern red oak (112 to 122% for height and DBH, respectively), and its relative height growth was more responsive to the removal of overstory root competition (197%). ^ Results from the first experiment suggest that intermediate light levels provided the most favorable conditions for seedlings to cope with and recover from water stress. The medium and high light treatments imposed in this study apparently improved seedling capacity to maintain leaf turgor under low leaf Ψ _pd, while the low and medium light treatments imposed in this study provided enough shade to increase relative A_net and g_s recovery, likely due to alleviated harsh environmental conditions. Findings from the second experiment suggest that under partial-canopy conditions, overstory root competition limited seedling growth and physiological development during establishment. Collectively, results from these studies demonstrate both positive and negative aspects of American chestnut development in shaded environments, and also indicate that regeneration of American chestnut under partial canopy is a viable restoration method.^

]]> Caleb Edward Brown Agriculture, Forestry and Wildlife|Biology, Plant Physiology http://docs.lib.purdue.edu/dissertations/AAI1534984 http://docs.lib.purdue.edu/dissertations/AAI1534984 Wed, 22 May 2013 15:44:57 PDT A growing body of evidence indicates that concussions depend not only on a single offending head impact, but also on the series of subconcussive head impacts prior to concussion. Talavage et al. have shown that several subjects in their cohort of high school football players exhibit substantial changes in their neural health due to subconcussive blows without developing any outward symptoms. They probed neural health through the use of functional magnetic resonance imaging (fMRI). Breedlove et al. subsequently demonstrated that changes in fMRI correlate with the number and location of head impacts experienced throughout the football season. ^ This work builds upon the analysis of Breedlove et al. Regression models based on an updated and expanded data set are presented. This analysis confirms that the number and location of subconcussive head impacts are factors in eliciting deleterious changes in neural health as measured by fMRI. Further analysis indicates that the peak linear acceleration of head impacts is also a factor in eliciting changes in fMRI. Collectively, these results indicate that the subconcussive injury mechanism is analogous to mechanical fatigue or soft tissue overuse injury. Furthermore, comparison of player head impacts based on position (i.e., linemen versus skill positions) indicates that player position may be a risk factor for subconcussive injury due to the large number of head impacts characteristic of linemen. ^ These analyses help elucidate the connection between head impact biomechanics and subconcussive pathophysiology. Analyses indicate that improvements in football equipment and changes in coaching and rules would likely have a protective effect in the prevention of subconcussive and concussive injury in football. ^

]]> Evan L Breedlove Biology, Neuroscience|Engineering, Biomedical|Health Sciences, Recreation|Biophysics, Biomechanics http://docs.lib.purdue.edu/dissertations/AAI1534982 http://docs.lib.purdue.edu/dissertations/AAI1534982 Wed, 22 May 2013 15:44:56 PDT Many binary star systems (e.g., pulsar-white dwarf) are known to possess significantly smaller companions, such as an exoplanet, in large orbits about the binary. Given that binary star systems exist far from the Earth, the interactions comprising their dynamical environment are unknown. Fundamentally, the motion of the exoplanet may be modeled using pairwise point-mass gravitational contributions from each of the two stars, assumed to possess similar masses. In this investigation, however, a three-body interaction is also considered. This extra force contribution is selected to depend inversely upon the product of the distances between the three bodies. The resulting model is constructed to reduce to the well-known circular restricted three-body problem as the three-body interaction is scaled to zero. A numerical frequency analysis is employed to examine the properties and prevalence of retrograde periodic and quasi-periodic orbits in the exterior region in the circular restricted three-body problem for a large mass ratio. Using these results as a baseline, a similar analysis is completed for various constants scaling the three-body interaction. The influence of this additional contribution is explored using the computed fundamental frequencies, which reflect changes in the underlying ordered dynamics in the vicinity of the binary. Poincaré maps are employed to confirm and explore the results of the frequency analysis. The results from this preliminary investigation suggest that the dynamics of an exoplanet in a large orbit about a binary star system are significantly altered by the inclusion of a three-body interaction.^

]]> Natasha Bosanac Physics, Astrophysics http://docs.lib.purdue.edu/dissertations/AAI1534983 http://docs.lib.purdue.edu/dissertations/AAI1534983 Wed, 22 May 2013 15:44:56 PDT The flaviviruses, including yellow fever, dengue, and West Nile viruses are pathogens that affect millions of people each year. Despite the wide prevalence of flavivirus infections, there are no treatment options after infection occurs. A high-throughput study aimed at developing new flavivirus therapeutics previously identified two candidate antiviral compounds, 3394 and 4088, that proved to target yellow fever nonstructural protein 4B (NS4B). NS4B's role in infection is poorly understood, and thus it was of interest to better understand NS4B's function in infection as well as develop the compounds as antivirals. To this end, a variety of biochemical techniques were employed to determine whether the compounds target any of the known functions of NS4B. Specifically, it was determined that the compounds do not inhibit NS4B oligomerization, its interaction with NS3 or NS5, its immune response evasion activity, or its targeting to the endoplasmic reticulum membrane. Immunofluorescence imaging, qRT-PCR, and synergy assays with C75 (a fatty acid synthase inhibitor) proved that the compounds target some function of NS4B necessary in early replication complex formation, suggesting a function of NS4B that has not yet been characterized. Furthermore, second generation compounds with reduced cytotoxicity target NS4B in a similar manner, thus proving that these compounds are excellent therapeutic candidates and can be used to gain insight into NS4B's role in infection.^

]]> Carolyn G Botting Biology, Virology http://docs.lib.purdue.edu/dissertations/AAI1534980 http://docs.lib.purdue.edu/dissertations/AAI1534980 Wed, 22 May 2013 15:44:55 PDT A parallel-through-the-road (PTTR) plug-in hybrid electric vehicle (PHEV) pairs an engine powering the front wheels of a vehicle with an electric motor powering the rear wheels. This arrangement gives the flexibility of being able to operate the vehicle in an all-electric mode, an all biodiesel mode, or a combination of both to create maximum power. For this work, a 1.7 L CIDI engine running on biodiesel will be the engine being used and a 103 kW Magna motor will power the rear wheels. In order to power the motor, a high voltage (HV) energy storage system (ESS) needs to be designed and integrated into the vehicle. ^ The goal for the mechanical design of the ESS is to create a structure that will enclose all of the batteries and battery control modules to protect them from environmental factors such as dirt and water as well as to prevent them from becoming dislodged in the event of a collision. The enclosure will also serve as a means to protect the consumer from the dangers of HV. The mechanical design also entailed designing a cooling system that will keep the batteries operating in an acceptable temperature range while they are charging and discharging. ^ The electrical design focused on designing a HV system that could adequately supply enough current flow to each component to meet the peak loading condition yet be able to disconnect should a fault occur to prevent component damage. The system was also designed with safety in mind. Controllers will constantly be monitoring both the HV and LV systems to make sure that each is isolated from the other. Should a controller detect a problem, it will disconnect the HV system. The electrical system will have a high voltage interlock loop (HVIL). The HVIL will be a continuous LV circuit that passes through every HV connector and various switches, so that, if a connector is unplugged or a switch is flipped, the circuit will open. A controller will be monitoring the HVIL for LV. Should it not detect LV, the controller will disconnect the HV system. ^ Several simulations and calculations were conducted as to whether six or seven batteries should be used. Seven batteries will allow the vehicle to accelerate quicker and have lower fuel consumption and emissions produced. However, there are several integration and cooling challenges that arise when trying to integrate seven batteries onto the vehicle. In the end, these challenges outweighed the benefits of seven batteries, and the six battery system was chosen. ^ On top of all of the design and simulation results discussed above, there were also many lessons learned in regards to managing the design team involved in this project. The best way found to keep all members on task was to split the project into smaller sections, create a timeline with specific tasks and corresponding completion dates, and assign a person to be responsible for each task. This helped to gauge whether the project was behind schedule but also gave each member a responsibility and ownership to the project. It was also established that the best way to transmit data was to have a secure, networked drive that allowed members to access it from any computer at any time. This gave members the flexibility to work whenever and wherever was most convenient for them and allowed them to easily share data amongst members without having to attach large files to emails.^

]]> Bryan Whitney D Belt Alternative Energy|Engineering, Automotive|Energy http://docs.lib.purdue.edu/dissertations/AAI1534981 http://docs.lib.purdue.edu/dissertations/AAI1534981 Wed, 22 May 2013 15:44:55 PDT The aim of this study was to measure the benefits and advantages perceived by Chinese parents of overseas summer camps by developing a framework in regard to several specific aspects of the camp and finding out how these attributes affected the overall perceptions of these camps to Chinese parents. Comparing the holistic development sought by local market of overseas summer camps, the analysis highlights the educational advantages of the overseas summer camps for Chinese market, particularly for the benefits of learning a foreign language, having children ready for future overseas study and getting complement to Chinese-style education. Results also suggest that educational resource of summer camp destination was identified as the most significant pull factor attracting Chinese parents. Specifically, advanced education system and selective well-known universities of the country or region where camp located are seen as highly appealing components of summer camp products from parents' perspectives. ^

]]> Chen Bi Recreation http://docs.lib.purdue.edu/dissertations/AAI1534978 http://docs.lib.purdue.edu/dissertations/AAI1534978 Wed, 22 May 2013 15:44:54 PDT The idea of using parallel coil arrays in magnetic resonance imaging (MRI) has been the focus of much research, specifically for the case in which multiple receive coils are used. Most prior transmit coil array research aims to match the excitation pattern as closely as possible to some theoretically designed target excitation. In order to improve the signal-to-noise ratio (SNR) these arrays are often used in conjunction with a high B ₀ field, resulting in adverse effects to both the patient and the image quality. The transmit coils must combat all of these effects. Past approaches attempt to optimize the physical properties of the system, despite the fact that these might lead to suboptimal reconstructed images. An additional development in recent years in MRI is that of coil selection in the receive coil array. Doing this reduces reconstruction time by choosing the coils which contribute the most to the reconstructed image. We propose taking a multiple-input multiple-output (MIMO) signal processing perspective for parallel transmit and receive signaling in which we try to optimize a performance metric given the constraints of the system. Given joint sensitivity information for the coils in the transmit and receive arrays, we can work within these constraints to maximize an objective function (e.g., SNR) given by combining techniques from sensitivity encoding (SENSE) and MIMO signal processing. The optimization of the objective function will be used to directly improve image quality. We use a process akin to beamforming to pick gain terms on the pulses generated by the transmit coils in order to optimize the chosen objective function to obtain better image quality. We propose techniques using small tip-angle assumption. We also combine this transmit optimization with receive coil selection.^

]]> Stephen Beckley Engineering, Biomedical|Engineering, Electronics and Electrical|Health Sciences, Radiology http://docs.lib.purdue.edu/dissertations/AAI1534976 http://docs.lib.purdue.edu/dissertations/AAI1534976 Wed, 22 May 2013 15:44:53 PDT Continuous flow microwave heating is an emerging technology in thermal processing of liquid, viscous, or pumpable food products such as carrot puree. Carrot (Daucus carota) is one of the world's leading vegetable crops. Consumption of carrot has increased due to its pleasant flavor, nutritious content and perceived health benefits related to vitamin A. Conventional thermal processing of carrot puree requires long processing times at high temperatures to inactivate Clostridium botulinum and achieve commercial sterility during the shelf life of the product. The excessive heat treatment causes degradation of nutrients, color, flavor, and texture. Microwave heating has advantages over conventional heating such as short come-up time, fast and efficient volumetrically heating. ^ In the present study, carrot puree was thermally processed by a lab-scale 6-kW continuous flow microwave system at 90°C and 141°C at different holding times. Carrot puree was also processed conventionally by a tubular heat exchanger to compare with microwave processing. In spite of differences in processing conditions, the effects of continuous flow microwave heating on color and carotenoids (&agr;-, β-carotene) content of carrot puree were found superior as compared to conventional heating. At high sterilization temperatures isomerization of β-carotene which could contribute to lower vitamin A activity was significantly lower (55%) in microwave processed carrot puree than its conventionally heated counterparts. In addition, in-vitro bioaccessibility studies indicated that heating of carrot puree increased the bioaccessibility of α- and β-carotenes between 5 to 22%, and thus their potential bioavailability. These findings support that efficacy of continuous flow microwave heating in preserving quality of carrot puree as compared to conventional heating methods.^

]]> Gulsah Bakir Agriculture, Food Science and Technology http://docs.lib.purdue.edu/dissertations/AAI1534977 http://docs.lib.purdue.edu/dissertations/AAI1534977 Wed, 22 May 2013 15:44:53 PDT The objective of this research is to apply recently developed femtosecond (fs) coherent anti-Stokes Raman scattering (CARS) spectroscopy diagnostic techniques on an unsteady jet diffusion flame. With the advantage of using a 5kHz repetition rate laser system, higher data rates can be achieved which will provide information of transient processes occurring in the diffusion flame which occur on time scales smaller than those measurable using current nanosecond CARS techniques. ^ In the experiment pump and Stokes pulses arrive at the probe volume simultaneously while the probe pulse is chirped using a 30 cm glass rod. The glass rod introduces a chirp in the probe pulse which forces the different frequency components of the pulse to leave the glass rod at different times due to their interaction with different indices of refraction. The pump and Stokes pulses excites the Raman transition and while the transitions first oscillate in phase they degenerate to their own natural frequencies which causes interference and Raman coherence decay. The chirped probe pulse interacts with this coherence to create the CARS signal while mapping the coherence decay to the frequency of the CARS signal. ^ CARS spectra is recorded in a near adiabatic Hencken burner and used as reference temperature spectra. Spectra is then recorded in an unsteady jet diffusion flame over various different radial positions at three different heights above the nozzle, x/d = 0.6, 2.0, and 15.0. The spectra recorded as a reference is input into an already developed spectral fitting code to calculate various laser parameters while holding the temperature constant. The laser parameters are then used to fit experiment spectra recorded in the jet flame to determine the temperature. Temperatures are detected in the jet flame from 400-2500 K while using laser parameters which provide low error levels when fitting to shots in those temperature ranges.^

]]> Devashish S Bangar Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1534595 http://docs.lib.purdue.edu/dissertations/AAI1534595 Wed, 22 May 2013 15:44:52 PDT The purpose of this study was to compare the quality of supervision and organizational culture existing within residential treatment centers (RTCs) serving youth as they influence the incidence of burnout among direct care staff. A survey designed to measure these components was completed by 128 direct care staff from Indiana and Chicago-based RTCs. While Supervision and Organizational Culture did not correlate strongly with Burnout in the multivariate regression analysis, the analysis did indicate that the main two factors correlated the most significantly with higher burnout scores were `working first shift' and `receiving health insurance' as a benefit. Supervision did show higher correlation with the Burnout, Emotional Exhaustion, and Depersonalization variables than did Organizational Culture, with Organizational Culture having stronger correlation than Supervision with Personal Accomplishment, but none of these correlations were significant. Findings suggest that RTCs need to be conscious of how the demands of first shift work differ from those of other shifts, and provide supervisors with additional training to help them understand why their first shift employees could be more prone to burnout so they can provide the support necessary to help them cope.^

]]> Steven Ryan Smethers Education, Social Sciences|Psychology, Industrial http://docs.lib.purdue.edu/dissertations/AAI1534596 http://docs.lib.purdue.edu/dissertations/AAI1534596 Wed, 22 May 2013 15:44:52 PDT The task of a keyword recognition system is to detect the presence of certain words in a conversation based on the linguistic information present in human speech. Such keyword spotting systems have applications in homeland security, telephone surveillance and human-computer interfacing. General procedure of a keyword spotting system involves feature generation and matching. In this work, new set of features that are based on the psycho-acoustic masking nature of human speech are proposed. After developing these features a time aligned pattern matching process was implemented to locate the words in a set of unknown words. A word boundary detection technique based on frame classification using the nonlinear characteristics of speech is also addressed in this work. Validation of this keyword spotting model was done using widely acclaimed Cepstral features. The experimental results indicate the viability of using these perceptually significant features as an augmented feature set in keyword spotting.^

]]> Padmalochini Umakanthan Engineering, General|Energy http://docs.lib.purdue.edu/dissertations/AAI1534594 http://docs.lib.purdue.edu/dissertations/AAI1534594 Wed, 22 May 2013 15:44:51 PDT Burying beetles, Nicrophorus orbicollis are unusual among insects in that they provide biparental care. They preserve carrion destined for their young by covering the flesh with oral and anal secretions having antimicrobial immune molecules. Immune defense mounted by individuals for the benefit of others is called social immune system and expected to be as costlier as other forms of immunity. Here we used the burying beetle, Nicrophorus orbicollis, a species that obligatory breed on carcasses of small vertebrates to investigate the role of nutrient rich carcasses and social immunity as antimicrobial strategies. We manipulated competition between beetles and microbes by providing beetles with fresh carcass, dipped carcasses, carcasses burdened with heat killed bacteria, and stale ones that had reached advanced putrefaction. We examined the effects of carcasses quality on life time reproductive output and costs of mounting a social immune response in the burying beetle. ^ Our experiments suggest that higher levels of microbial competition on the carcass have strong detrimental effects on beetle reproductive success and larval growth. ^ We conclude that microbe rich breeding environment has selected for an atypical pattern of immune defense with a significant up regulation of social and personal immunity and this eventually reduces lifetime reproductive success. We suggest that the costliness of the immune response is a source of tradeoff between immunity and other life-history traits, such as reproduction and parental care.^

]]> Manoj Sabnani Biology, General|Biology, Ecology|Biology, Microbiology|Health Sciences, Immunology http://docs.lib.purdue.edu/dissertations/AAI1534592 http://docs.lib.purdue.edu/dissertations/AAI1534592 Wed, 22 May 2013 15:44:50 PDT Resources play a fundamental role in immune response and reproductive effort and life strategy in insects. The biparental burying beetle Nicrophorus orbicollis regulates brood size according to resource availability, but costs of mounting an immune response during a reproductive bout are not known. Carcass size manipulation and nylon implantation was done which elucidated a trade-off between reproduction and immunity, and the resulting life strategy changes were analyzed. By testing phenoloxidase and lysozyme-like activity we showed that there was an increase in the immune system in breeding females, with differing levels of phenoloxidase and lytic activity depending on the amount of resources available during reproduction. Immune-compromised individuals showed increased phenoloxidase activity, higher rates of encapsulation, and decreased lysozyme-like activity when stressed with manipulated resources. A trade-off was elucidated between immune parameters measured, supporting terminal investment behavior and allocation of resources to the current reproductive bout.^

]]> Jeffrey D Radloff Biology, General|Biology, Ecology|Biology, Entomology http://docs.lib.purdue.edu/dissertations/AAI1534593 http://docs.lib.purdue.edu/dissertations/AAI1534593 Wed, 22 May 2013 15:44:50 PDT Computational fluid dynamics simulation is a tool to better understand the behavior of the gas-solid flow and in-furnace performance of blast furnace. This thesis consists of four parts. First, development and use of a mathematical model to predict the burden distribution which has a great effect on gas distribution and furnace efficiency. Second, simulate the blast furnace shaft process considering chemical reactions, heat exchanges, and gas-solid flow dynamics. Third, validate the burden distribution model and shaft simulation model using plant measurement. Fourth, to conduct parametric study of the major operational parameters i.e. effect of PCI rate, natural gas injection, bosh gas temperature, moisture add, oxygen enrichment, chimney size, and furnace geometry. Simulation is conducted using plant data and a good agreement is observed comparing with plant measurement. The parametric study showed that it is possible to improve the furnace performance by oxygen enrichment, adding moisture. It is also possible to decrease the coke rate by charging more PCI and increasing natural gas injection. Chimney size and furnace geometry can also affect a lot on the gas distribution and pressure drop. The burden distribution model and shaft CFD model can be used as a combination tool to predict the internal condition of a blast furnace.^

]]> Taifur Rahman MD. Engineering, General|Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1534588 http://docs.lib.purdue.edu/dissertations/AAI1534588 Wed, 22 May 2013 15:44:49 PDT The main purpose of this work is to develop a wind energy conversion system model to analyze the behavior of a permanent magnet synchronous generator (PMSG) for variable speed application. The PMSG modeling in this study is done using the approach of state space representation of the d-q models theory for AC machines. ^ In this work, the MATLAB/Simulink programming and graphical environment has been used to develop the wind energy conversion system modeling and simulation. This modeling includes the wind turbine and the PMSG models. Using this simulation tool, the dynamic analysis and performance evaluation has been achieved for a 1KW PMSG. All the system components and system response have been observed closely under different wind speeds. ^ This research analyzes the model of a variable speed wind turbine equipped with 1 KW PMSG. The wind energy conversion system is emulated with a complete test-bed to validate the theoretical and simulation results. The test-bed includes the PMSG, a Three-phase induction motor, a rectifier, sensors measuring the generators line-to-line voltages, two phase currents, the rectifier's output DC current and the rotational speed of the shaft. A variable frequency drive (VFD) is used to control the motor for providing variable speeds to the PMSG for analyzing the behavior. A charge controller is used for a battery charging application of the system.^

]]> Sudeshna Khan Engineering, General|Engineering, Electronics and Electrical|Energy http://docs.lib.purdue.edu/dissertations/AAI1534591 http://docs.lib.purdue.edu/dissertations/AAI1534591 Wed, 22 May 2013 15:44:49 PDT This pilot study examined whether or not txtspk was prevalent in formal student writing at the high school sophomore level. The study was based on Plester, et al's (2008) study that broke down txtspk into five different categories. The study was done in as scientific a method as was possible given the time constraints of the teachers who cooperated with their students to participate in the study. ^ The findings suggest that there is no indication of txtspk transferring over into the formal writing of high school sophomores. This supports the ideas that researchers in technology and learning have posited indicating that despite the new word that have come into the English language because of technology, students are aware of when it is proper to use txtspk and when it is not. ^ There are some limitations to this study, a few of which include the depth of training of the proctors of the writing sample, the training of the readers, and the number of writing samples that were collected. However, this pilot study offers an glimpse into what other, more in-depth studies might show.^

]]> Raymond Adam Palasz Education, General|Language, Rhetoric and Composition http://docs.lib.purdue.edu/dissertations/AAI1534587 http://docs.lib.purdue.edu/dissertations/AAI1534587 Wed, 22 May 2013 15:44:48 PDT The area of Future Internet research focuses on developing a new network with similar magnitude as today's Internet but with more demanding and complex design goals and specifications. It strives to solve the issues identified in today's Internet, by capitalizing on the advantages of emerging new technologies in the area of computer networking such as OpenFlow, Autonomic computing or Cloud Computing. By combining these technologies and applying them together significant progress is made in the development of an enhanced, more complex, but also more secure, reliable and scalable Internet. ^ This thesis focuses on the development of a complete system, designed with the new requirements of the Future Internet in mind, which builds on OpenFlow, Autonomic Computing and Cloud Computing technologies, and aims to provide, monitor and enhance the very popular video streaming service of today's Internet. One of the main goals is to show, how such a system can function under unstable, changing network conditions, how it can dynamically learn its environment recognize potential service degradation problems and react to these in an autonomic manner without the need for human intervention. ^

]]> Levente Ilyes Engineering, General|Engineering, Electronics and Electrical|Information Science http://docs.lib.purdue.edu/dissertations/AAI1534584 http://docs.lib.purdue.edu/dissertations/AAI1534584 Wed, 22 May 2013 15:44:48 PDT The primary objectives of this study include the numerical simulation of small scale Helical Twisted Vertical Axis Wind Turbine (VAWT) to analyze flow field through and around it and to determine suitable siting conditions along with the wake consideration generated by the turbine rotation. Siting of the small scale VAWT is a prime concern to maximize power output from the turbine. The numerical simulation approach has advantages for obtaining the effect on flow field to determine the wake effect resulting from the turbine. Numerical simulations of fluid flow for VAWTs have been analyzed. Governing properties of the flow field are measured (i.e. velocity fluctuation and wake effects) for various conditions by the commercial software Fluent®. Simulation has been conducted for the steady state condition and the phenomenon can be described by the Navier Stokes equations. The aerodynamic performance of VAWT has been simulated using Computational Fluid Dynamics (CFD). The variation of the variable characteristics for different elevations, conditions and geometries has been considered. Simulation of the VAWT is done based on wind tunnel testing conditions as a standard formulation for the all types of wind turbine testing numerically. Design conditions were based on the VAWT currently installed and operated on the roof of the Student Union Library (SUL) building on the Purdue University Calumet Campus. Validation of this type work is generally done experimentally from the commercial point of view. Recommendations for the possible improvement of the existing turbine and potential siting have been made.^

]]> Sanjit Kumar Basak Alternative Energy|Engineering, General|Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1534583 http://docs.lib.purdue.edu/dissertations/AAI1534583 Wed, 22 May 2013 15:44:47 PDT Recent advancement in wireless communications and electronics has enabled the development of Wireless Sensor Networks (WSN). WSNs are being deployed in a variety of location-aware applications, where the measurement of data is meaningless without accurate location. Many localization algorithms have been proposed in order to increase the accuracy and minimize the cost requirements. Artificial intelligence techniques such as Fuzzy logic and neural networks can be utilized as effective methods to satisfy these requirements. ^ In this thesis, we present two efficient artificial intelligence-based localization algorithms for WSNs. In the first algorithm, we implement a Sugeno-type fuzzy system with a collaborative communication feedback to achieve an accurate and cost effective two- dimensional (2D) localization system. In the second algorithm, the idea of the 2D localization using neural network is extended to achieve a three-dimensional (3D) localization with simplicity, location accuracy, and low cost. The proposed approach is also able to localize mobile nodes with unpredictable movement patterns. The simulation results depict the performance and the effectiveness of each approach.^ Keywords: Wireless sensor network, Fuzzy logic, Neural networks, Localization, Location accuracy, Cost effective, Mobility.^

]]> Mohammad Jaser Abdel-hadi Engineering, Electronics and Electrical http://docs.lib.purdue.edu/dissertations/AAI1534559 http://docs.lib.purdue.edu/dissertations/AAI1534559 Wed, 22 May 2013 15:44:47 PDT P-glycoprotein, a member of the ATP-binding cassette family of transporters, is an efflux transporter that transports a wide range of drugs and hence has significant effects on the disposition of its substrates. A number of drug-drug interactions have been attributed to modulation of P-gp function in different tissues. Digoxin is a P-gp substrate that is not metabolized and is almost exclusively transported by P-gp. It is considered a sensitive and specific probe and is recommended by the U.S. FDA for in vitro and in vivo assessment of P-gp transport function. Green tea is a widely used dietary ingredient and herbal supplement worldwide. Polyphenols in green tea have been shown to modulate P-gp function in vitro and hence the possibility of clinically significant DDI when green tea is co-administered with P-gp substrates needs to be investigated. This study was conducted to study the effects of green tea on P-gp function, in humans, using digoxin as a P-gp probe. ^ To compare digoxin pharmacokinetics with and without the co-administration of green tea, a cross-over design was employed. Eight healthy volunteers were enrolled in and completed the two-phase study. Plasma samples for determination of digoxin concentrations were collected for the first 4 hrs in both phases. A pharmacokinetic non-compartmental analysis was performed to derive digoxin pharmacokinetic (PK) parameters (area under the digoxin plasma concentration-time curve "AUC_(0-4)", maximum plasma concentration "C_max", and time for maximum plasma concentration "t_max"). In addition, digoxin pharmacodynamic (PD) parameters (area under the effect curve for PR interval "AUEC_PR-24", area under the effect curve for heart rate "AUEC_HR-24", maximum change in PR interval from baseline within 24 hrs "MAX_PR-24", and maximum change in heart rate from baseline within 24 hrs "MAX_HR-24") were derived from electrocardiographic measurements collected during each of the two phases. Digoxin PK and PD parameters from each of eight subjects were compared between the two phases using a paired Student's t-test or Wilcoxon signed rank test (for non-normally distributed data) to test for any significant differences associated with co-administration of green tea. ^ Digoxin median C_max and t_max values were similar in both water and green tea phases whereas mean AUC_(0-4) was slightly, but not statistically significantly, higher on the water phase (p=0.148). The mean (±SD) AUEC_PR-24 values were 4043 (±704) and 3907 (±660) msec*hr for water and green tea phases (p=0.064). Similarly, the mean AUEC_HR-24 was similar for the two phases (1704±129 and 1670±187 bpm.hr, respectively, p=0.42). The mean (±SD) Max _PR-24 for the water phase (11.1±8.3) was more than double that for the green tea phase (5.0±5.7) although the difference was not statistically significant (p=0.124). Conversely, the median Max_HR-24 for the water phase (5.5, range=0-44) was less than half that for the green tea phase (12, range=10-45) but the difference did not reach statistical significance (p=0.058). Other than few asymptomatic and reversible episodes of bradycardia and prolonged PR intervals, no subjects experienced any adverse effects of the co-administration of digoxin and green tea. ^ In conclusion, acute green tea administration does not cause any significant changes in digoxin pharmacokinetics or digoxin mediated cardiac electrocardiographic effects. Co-administration of green tea and digoxin (0.5 mg) is well tolerated and not associated with any significant adverse effects. Consequently, co-administration of green tea (at amounts similar to those used in this study) with P-gp substrates is not expected to lead to significant changes in substrate exposure and hence the combination can be considered safe.^

]]> Ahmed Nader Ahmed Mohamed Mohamed Health Sciences, Pharmacology|Health Sciences, Pharmacy http://docs.lib.purdue.edu/dissertations/AAI1534424 http://docs.lib.purdue.edu/dissertations/AAI1534424 Wed, 22 May 2013 15:44:46 PDT The expansion of a fictional world occurs when a previous narrative of fiction is perpetuated through future publication. The task of the author is to maintain believability with the reader by adhering to the same fictional standards left by the previous publication. If there is minimal departure from the original content then the reader will accept the new addition to the fictional world. If believability is broken then the reader can become so displeased that it might lead to consequences in the fictional world. The fans of Sherlock Holmes influenced Sir Arthur Conan Doyle to resurrect the world's greatest detective because his demise simply broke the persona of Sherlock Holmes, destroyed the fictional world, and thus displeased the reader. ^ Traditionally, the expansion of a fictional world falls to its creator and original author. However, there are instances where a collaborative effort of multiple authors has expanded a fictional world by working in the same narrative, thus strengthening believability through a system of self-editing and recognition from other authors' publications. I will use the term "contributive" narrative to describe this process while analyzing the realm of professional publication and the personal creativity of fan fiction. ^ H.P. Lovecraft and his circle of authors utilized contributive narrative to expand upon Lovecraft's Cthulhu Mythos. Through the non-formal editorial influences of H.P. Lovecraft, the circle created a type of game where each author's contribution receives verification through another author's publication. Lovecraft's non-formal editorial influence made sure that the core elements of his Cthulhu Mythos, concepts of cosmic horror, and the making of weird tales were maintained. This informal editorial regulation between colleagues draws a distinct comparison to the Algonquin Circle where the members regulated the quality of the content in circulation. While on the surface there is a parallel between the editorial process of the Algonquin Circle and Fanfic, in the form of criticism that crosses the line into savage insults, on a deeper level the two are quite different. While both rely on peer review to edit and control the group dynamic, within the Algonquin Circle is a concentrated group of individuals in the professional field of writing and publication devoted to an exclusive sense of satirical humor. The first filter of the Algonquin Circle was acknowledgement through publication. This exclusivity is in direct opposition to the open forum of Fanfic where anyone can submit unpublished work to be critiqued by any reader. The editorial criticism found in the Lovecraft Circle can be considered less vicious than in the Algonquin Circle. ^ The Lovecraft Circle stands as a hybrid example of a controlled Fanfic that expands a fictional world using techniques from contributive narrative, publication, and acknowledgment. With the support of literary theories and research from accredited Lovecraft scholars, there is concrete evidence that the Lovecraft Circle can be classified as a true literary circle that stands apart from postmodern writing circles.^

]]> Joseph A Lesny Literature, General|Literature, American http://docs.lib.purdue.edu/dissertations/AAI1531030 http://docs.lib.purdue.edu/dissertations/AAI1531030 Wed, 22 May 2013 15:44:46 PDT Unprecedented capabilities for the detection of nuclear particles are presented by tensioned metastable fluid states which can be attained via tailored resonant acoustic systems such as the acoustic tensioned metastable fluid detection (ATMFD) system. ATMFD systems are under development by our group at Purdue University. Radiation detection in ATMFD systems is based on the principle that incident nuclear particles interact with the dynamically tensioned fluid wherein the intermolecular bonds are sufficiently weakened such that even fundamental particles can be detected over eight orders of magnitude in energy with intrinsic efficiencies far above conventional detection systems. Experimentation was performed to prove that these detection events form preferentially in the direction of incoming radiation, therefore, enabling the capability to ascertain information on directionality of incoming radiation—an unprecedented development in the field of radiation detection. This study presents the development of directional capabilities of the ATMFD system by utilizing enhanced signal processing-cum- signal analysis, refined computational algorithms, and on demand enlargement of the detector sensitive volume. Advances in the development of the directional capabilities of the ATMFD system were accomplished utilizing a combination of experimentation and theoretical modeling. Modeling methodologies include Monte-Carlo based nuclear particle transport using MCNP5 and complex multi-physics based assessments accounting for acoustic, structural, and electromagnetic coupling of the ATMFD system via COMSOL’s Multi-physics simulation platform. Benchmarking and qualification studies have been conducted with special nuclear material (SNM)(Pu-based neutron-gamma sources). These results show that the ATMFD system, in its current configuration, is capable of locating the direction of a hidden radioactive source to within 30° with ~100% confidence. ^

]]> Brian C Archambault Engineering, Nuclear http://docs.lib.purdue.edu/dissertations/AAI1530493 http://docs.lib.purdue.edu/dissertations/AAI1530493 Wed, 22 May 2013 15:44:45 PDT Economic analysis is an important component for the decision-making involved in highway projects. However, the Indiana Department of Transportation (INDOT) lacks a uniform and comprehensive methodology or model to evaluate highway improvement projects. This research project seeks to fill that gap. The preferred methodology is called life-cycle benefit cost analysis. The two key parts in the proposed model, Indiana Life-Cycle Benefit Cost Model (ILCBCM), are agency costs and user benefits. Agency costs include initial costs, routine maintenance costs, rehabilitation costs, and salvage value of the facility. User benefits contain travel time savings, vehicle operating cost savings, and accident reduction savings. By analyzing Indiana's traffic data and referring to the existing methods used in other highway agencies, the framework and calculation procedures for each module are developed. The probabilistic analysis model is then incorporated into ILCBCM so that the outputs can be expressed as ranges of values with likelihoods of occurrence, which is more realistic when evaluating projects with high risks. In order to illustrate the overall economic analysis process, a software application, called Indiana Economic Analysis Tool (IEAT), is developed. A case study was performed to reflect the convenience and flexibility of the software.^

]]> Guangyuan Zhao Economics, General|Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI1530494 http://docs.lib.purdue.edu/dissertations/AAI1530494 Wed, 22 May 2013 15:44:45 PDT HUB-based telerobotics is the study of the design and development of networked telerobots in the HUB environments. In this thesis, collaborative control mechanisms are investigated for more efficient and effective utilization of telerobots in the HUB, compared with conventional networked telerobots. In direct control scheme, an aggregation algorithm is used to integrate multiple control signals from operators for robot control. The aggregation is dynamically adjusted according to operators' performance. In supervisory control scheme, structured collaborative insights management is developed to support innovation idea exchanges and consensus decision-making. In addition, networked agent-based conflict and error prevention is investigated for early conflict/error detections to reduce the risk of damage. ^ Two cases of HUB-based telerobotic systems are implemented in this work. In case study A, networked telerobots are used for a simulated nuclear plant decommissioning through vision-based hand gesture interface. The experiments show that collaborative control is more effective and less susceptible to conflicts/errors than the standard single operator control. The system can reliably recognize operators' hand gestures with a 96% detection rate in cluttered backgrounds. Collaboration between experts and novice operators can reduce the time to complete the multi-step task, compared to a single operator, either an expert or novice. In case study B, a HUB-based telerobot is integrated into a collaborative engineering design system for experimental electronic device (including both hardware and software design). Compared with other collaborative design tools and networked telerobots, the system for collaborative electronics design is an economical and powerful integrated collaboration support system which enhances productivity and sharing of knowledge by collaborative intelligence and innovations by designers.^

]]> Hao Zhong Engineering, Computer|Engineering, Industrial|Engineering, Robotics http://docs.lib.purdue.edu/dissertations/AAI1530491 http://docs.lib.purdue.edu/dissertations/AAI1530491 Wed, 22 May 2013 15:44:44 PDT In order to further scale down Si CMOS technology beyond 10 nm node, alternative high-mobility channel materials are needed. The low-field high electron mobility for narrow bandgap III-V semiconductors such as InAs and InSb and high hole mobility for Ge and GaSb make them possible to operate at low drain and gate bias voltages thus with low power dissipation. To enable high-mobility channel materials for logic applications, the oxide/semiconductor interface quality is essential. ^ In this thesis, I mainly focus on the interface studies of atomic-layer-deposited (ALD) Al₂O₃ as gate dielectric on narrow bandgap materials such as InSb and InAs, for n-channels and GaSb and Ge for p-channels. By using multi-frequency capacitance-voltage (C-V) and conductance-voltage (G-V) approaches, we can determine the D_it (Interface Trap Density) vs energy level within the semiconductor bandgap. The interface study includes both (100) and (111) orientations since the atomic structure on different crystal orientations plays a very important role in terms of the interface quality. We apply the Trap Neutral Level (TNL) concept at the "defective" oxide/semiconductor interfaces to explain the experimental results, in particular, at InAs MOS interface. ^ In addition to the interface study, we also investigate to apply complex oxides or higher-κ dielectrics on III-V or Ge in order to reduce the equivalent-oxide-thickness (EOT) down to 1-2 nm as required by International Semiconductor Technology Roadmap[1]. We discover ALD complex oxides (such as La_xY_1-xO₃ with κ∼20) can be epitaxial grown on Ge(111) and other (111) oriented semiconductor surfaces. Detailed interface characterizations of La_xY_1-xO ₃ on Ge (111) and Ge (100) are presented in this thesis.^

]]> Jingyun Zhang Engineering, Electronics and Electrical|Nanotechnology http://docs.lib.purdue.edu/dissertations/AAI1530492 http://docs.lib.purdue.edu/dissertations/AAI1530492 Wed, 22 May 2013 15:44:44 PDT While China is one of the most popular destinations for expatriates, it is also a place in which many struggle to succeed. Expatriates—a critical component of the complex business environment that is developing in China and East Asia as a result of rising direct foreign investment—are challenged in multiple life domains by their overseas' experiences. Much research has been conducted on the working lives and adaptations of expatriates to their new environments, but their leisure activities have largely been ignored. This study explores leisure behaviors of expatriates in China and the effect of these behaviors on their level of cross-cultural adaptation. The present study investigated the leisure behavior changes of expatriates who moved to China and how such changes related to their overall life adjustment in the new country by examining their cross-cultural adaptation level. The current research included two stages: quantitative and qualitative. The quantitative study examined the leisure behavior changes in daily and vacation settings of 205 respondents and how those changes corresponded to different levels of cross-cultural adaptation. The results demonstrated that general patterns of leisure participation changed after expatriates started living and working in China. They also suggested that higher levels of cross-cultural adaptation were present in expatriates who started new leisure activities in both daily and vacation settings, especially if those expatriates had higher host language capacity. The qualitative study explored motives of and barriers to the leisure experience of 19 expatriates living in China through personal interviews. The constraints they reported include lack of resources and facilities, as well as language barriers. In the vacation setting, changes in leisure activities participation were discussed under the following thems: frequency, destination choices, activities, and destination facilities. This research sheds light on the changes that expatriates experience in leisure life, both in daily and vacation settings and assists expatriates with better expatriation experiences. It serves as a useful starting point for future investigation about leisure studies of expatriates and provides rich information for industry practitioners and employers to better assist expatriates with life adjustment in the new environment. Limitations and recommendations for future research were also included.^

]]> Xuan Zhang Asian Studies|Sociology, Theory and Methods|Cultural Resources Management http://docs.lib.purdue.edu/dissertations/AAI1530489 http://docs.lib.purdue.edu/dissertations/AAI1530489 Wed, 22 May 2013 15:44:43 PDT With an increasing number of people traveling with their dog(s), dog-friendly hotels have emerged to meet the specific need of dog owners. Since hotels that allow dogs need to take care of both dog-owning and non-dog-owning guests, regulations about dogs at hotels are critical to the hotel management. The present study investigates people's attitudes towards dogs in hotel settings from the perspective of hotel pet policies. A clear and effective hotel pet policy is found to be a necessity for dog-friendly hotels to protect both the hotel and its guests. Results indicate important issues regarding dogs at hotels and attitudinal differences among groups of respondents. The research also found that inaccessibility to information of current hotels that allow dogs and a lack of dog-friendly accommodations may result in the gap of the dog-friendly segment in the hotel industry. Practical guidelines especially about hotel pet policies are provided to hoteliers who want to compete in the dog-friendly hospitality segment.^

]]> Yawei Zhang Sociology, Theory and Methods|Business Administration, Management|Sociology, Public and Social Welfare http://docs.lib.purdue.edu/dissertations/AAI1530490 http://docs.lib.purdue.edu/dissertations/AAI1530490 Wed, 22 May 2013 15:44:43 PDT Communities across the United States and elsewhere have turned to various community based events to celebrate local heritage and culture. This study investigated the relationship between the attributes of community-based heritage events and participants' perceived value. A conceptual model based on the Means-End theory was proposed and empirically tested. The context of the empirical study was a community-based heritage event in a town located in the Midwestern region of the United States. The results of this study highlighted four attribute factors of community-based heritage festivals, namely, Historical Re-enactment, Social Interactions, Event Design and Physical Facets. Each attribute factor contributed differently to the perceived value dimensions. Furthermore, participants' perceived benefits of their festival experience mediated the relationships between event attributes and perceived value. The theoretical and practical implications of the findings also are discussed.^

]]> Wenqian Zhang Sociology, Theory and Methods http://docs.lib.purdue.edu/dissertations/AAI1530488 http://docs.lib.purdue.edu/dissertations/AAI1530488 Wed, 22 May 2013 15:44:42 PDT Global warming concerns our society, and one of the most challenging scientific questions is specifically how the global climate will change. Greenhouse gases (e.g., CO₂ & CH₄) have been recognized as playing a significant role in climate change. In order to analyze climate change, it is important to know what carbon fluxes and pool sizes are now, and how they are going to change in the future. In this project, I use a process-based biogeochemical model, the Terrestrial Ecosystem Model (TEM) to quantify the major greenhouse gas (CO₂ & CH₄) exchanges in the region of Northern Eurasia in the late 20^th (1970-2000) and 21^st century. I use a 31-year historical climate dataset from 1970 to 2000, and also data from six MIT Integrated Global System Modeling Framework (MIT-IGSM) simulation climate scenarios and four Intergovernmental Panel on Climate Change (IPCC) SRES simulation climate scenarios from 2001 to 2100 to examine carbon changes (CO₂ & CH₄) in this region. I compare these ten simulation scenarios through a sensitivity and uncertainty analysis. For the late 20^th century, the terrestrial ecosystems in this region are estimated to emit CH₄ at a rate of 22 Tg CH₄ yr-1 (1 Tg = 1012g), while the net sink of CO₂ is about 0.09 Pg C yr^-1 (1 Pg = 10¹⁵g). The region, therefore, is estimated to emit 0.22 Pg CO₂ equivalent greenhouse gases into the atmosphere, given the assumption that a greenhouse effect of 1 g CH₄ is equivalent to that of 25 g CO₂ on a weight basis. Large discrepancies in model estimations are found for different climate change scenarios in the 21^st century. Greenhouse gas emissions in the region are predicted to increase up to 58 Tg CH ₄ yr-1 and 3 Pg CO₂ yr-1 by the end of 21^st century. I also find that, under the IPCC A1FI scenario, the region has the largest emissions of these greenhouse gases, and becomes a carbon source, while the IPCCB1 scenario provides the most conservative estimates relative to the other scenarios.^

]]> Zhiwei Zhang Biology, Ecology|Environmental Sciences http://docs.lib.purdue.edu/dissertations/AAI1530486 http://docs.lib.purdue.edu/dissertations/AAI1530486 Wed, 22 May 2013 15:44:41 PDT Optimal Definitions of Residue Contact Definitions: Effective encoding of residue contact information is crucial for protein structure prediction since it has a unique role to capture long-range residue interaction as compared with other commonly used scoring terms. The residue contact information can be incorporated in structure prediction in several different ways, including in the form of statistical residue contact potentials or to use predicted residue contacts as restraints or an additional term in the scoring function. To seek the most effective definition of residue contacts for the template-based protein structure prediction, we evaluated thirty different contact definitions, varying bases of contacts and distance cutoffs, in terms of their ability to identify proteins of the same fold. ^ We found that, overall, the residue contact pattern can distinguish protein folds best when contacts are defined for residue pairs whose Cβ atoms are at 6.5 Å or closer to each other. Lower fold recognition accuracy was observed when inaccurate threading alignments were used to identify common residue contacts between protein pairs. In the case of threading, alignment accuracy strongly influences the fraction of common contacts identified among proteins of the same fold, which eventually affects the fold recognition accuracy. The largest deterioration of the fold recognition was observed for β-class proteins when the threading methods were used because the average alignment accuracy was worst for this class. When results of fold recognition were examined for individual proteins, we found that the effective contact definition depends on the fold of the proteins. A larger distance cutoff is often advantageous for capturing spatial arrangement of the secondary structures, which are not physically in contact. For capturing contacts between neighboring β strands, considering the distance between C&agr; atoms is better than the Cβ-based distance because the side-chain of interacting residues on β strands sometimes point to opposite directions. ^ Participation in CASP9: We participated the 9th Experiment on the Critical Assessment of Techniques for Protein Structure Prediction (CASP9), using template-based protein structure prediction method SUPRB. Structure models were evaluated by comparing to experimentally solved structures in terms of RMSD values and GDT-TS scores. Results suggested valid performance on some of the targets yet room of improvement for SUPRB method.^

]]> Chao Yuan Biology, Bioinformatics|Biophysics, General http://docs.lib.purdue.edu/dissertations/AAI1530487 http://docs.lib.purdue.edu/dissertations/AAI1530487 Wed, 22 May 2013 15:44:41 PDT Zakrajsek, Andrew James. M.S.M.E., Purdue University, May 2012. Experimental and Numerical Analysis of Water Blast Mitigation: Focusing on Solid Water Barriers, Water Sprays, and Water-Sheets. Major Professor: Steven F. Son. School of Mechanical Engineering. An explosion yielding a blast wave can cause catastrophic damage to people and property. To mitigate damage from such an event, a number of investigators have proposed the use of water in various configurations as a shield around a target. Water is very easily controlled, stored, and acquired which makes it a robust choice for a possible source of a readily available blast mitigant. Multiple water configurations were experimentally and numerically tested to compare and understand the potential of various water configurations as possible blast mitigants. The study of multiple water configurations yielded two main focuses for this research. One of the focuses of this research was to compare multiple water configurations to better explain the underlying physical blast mitigating mechanisms associated with water blast mitigation and blast mitigation in general. The other focus was to highlight the most advantageous water configuration for possible large scale blast mitigation shielding for a high risk target. ^ The experimental work was completed by testing multiple water configurations under blast loading. Each water configuration was experimentally tested with an explosively driven shock tube and specific diagnostic measurement equipment. The water configurations tested include solid water barriers, water sprays, and water-sheets. The mass of water was shown to be relatively similar for the solid water barriers, water-sheet, and water spray. Therefore general blast mitigating comparisons between each water configuration were made knowing minimal mass loading effects were present. The results of each water configuration test helped highlight specific advantageous blast mitigating mechanisms. These advantageous mitigating mechanisms were shown to be; continuous surface areas, impedance mismatches, unconfined masses, controlling for breakup of water configuration, and mass loading. The understanding of these blast mitigating mechanisms meet the first focus and can be used to help design future water mitigation systems or other blast mitigating materials. ^ The most advantageous blast mitigating water configurations was found to be an unconfined free-flowing water-sheet. Here, an approximate water-sheet thickness of 0.3 cm was tested. The results show that the water-sheet mitigates the initial peak overpressure and impulse of the blast. Further insights into the underlying physics are revealed by a numerical simulation using Sandia's CTH hydrocode. In simulations and experiments, the air behind the water-sheet experiences two distinct pressure peaks. An initial pressure rise results from the passage of a low pressure blast wave (M ≈ 1) through the intact sheet and into the air downstream of the water-sheet. Following this, the water-sheet breaks apart due to an increase in pressure on the forward surface caused by the buildup of the subsonic detonation products. Passage of the detonation products after breakup results in a second rise in pressure behind the water-sheet. In simulations, an initial perturbation of the water-sheet is shown to affect the breakup time significantly. Additional simulations show that increasing the sheet thickness tends to increase the blast wave mitigation. These results indicate that it may be possible to optimize the thickness and surface morphology of a water-sheet to effectively mitigate damages due to explosive blast waves through the use of a water-sheet shield. ^

]]> Andrew James Zakrajsek Engineering, General|Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1530484 http://docs.lib.purdue.edu/dissertations/AAI1530484 Wed, 22 May 2013 15:44:40 PDT Powerful and programmable Graphics Processing Units have become commonplace in consumer-grade computers sold or built today. These GPUs have not only made it possible for users to play the latest video games, but also conduct high performance computing at a relatively inexpensive cost. The CUDA Framework, by NVIDIA, allows users to create or run highly parallel programs that run on a computer's GPU. One application of highly parallel computing is for brute forcing passwords. This research analyzes the performance of NVIDIA GPU's for cracking the passwords of encrypted files stored within ZIP archives. The research conducted aims to fill in gaps in existing research. Specifically, this research examines the relationship that the number of encrypted files has on a brute force time. Additionally, this research compares performance across different encryption types and file sizes. The results of the research were significant, adding to the knowledge of GPU-accelerated ZIP file brute force attacks.^

]]> John A. Yamich Information Technology|Computer Science http://docs.lib.purdue.edu/dissertations/AAI1530485 http://docs.lib.purdue.edu/dissertations/AAI1530485 Wed, 22 May 2013 15:44:40 PDT In this thesis, two types of contact problems are studied by different methods. In the first, a multi-scale model enables investigation of the effect of surface roughness on adhesive contact. Molecular dynamics simulation captures the atomic-scale effects of individual asperities while a finite element model captures the micro-scale contact mechanics. The relationship between force and distance predicted by the atomistic model is introduced into the finite element model through non-linear hysteretic springs which will be assigned random lengths and distribution to form the rough surface over the finite element model. The multi-scale model predicts how the energy loss, quantified by the hysteresis loop formed by loading and unloading data, is affected by indentation depth and surface roughness. The other contact problem is a practical engineering problem of multiple asperities with random radii and distribution in a contact with a rigid plate that is analyzed via a 2-D finite element model. The solution starts with the investigation of single asperity where the numerical results are verified by the analytical solution of the Hertzian theorem. Then the number of asperities is increased and the load required for a full contact of those asperities is calculated. The results reveal a linear relationship between the load and the number of asperities. In summary, this thesis has presented a detailed analysis on introducing the atomic simulation results into a finite element model. In addition, a much larger engineering model is also built to extend our work for a better understanding of multi-scale simulation of nanoindentation.^

]]> Lingqi Yang Engineering, Mechanical|Nanotechnology http://docs.lib.purdue.edu/dissertations/AAI1530483 http://docs.lib.purdue.edu/dissertations/AAI1530483 Wed, 22 May 2013 15:44:39 PDT This investigation explored the role data visualization in the scientific community and its effect on the cognitive ability of an individual. The research attempted to answer the question, " Whether appropriate data visualization helps in better understanding of corporate financial data?" and used quantitative methods to gain an insight. Participants in the study were divided into two groups of 30 each, with one group receiving the treatment devised for the research and the other using the common prevalent method. Both the groups were subjected to a test, based upon the analysis of which a conclusion was derived. The subjects were tested on their cumulative scores on the test as well as the time taken to complete the test. The resulting analysis concluded that visualization did influence the scores and time taken although the difference was more prominent for the scores than for the time. This meant that the particular visualization impacted the accuracy more than the speed. Although this could be disputed by the inverse relationship shared by accuracy and speed, it is in line with the purpose of a true visualization which should aid in better understanding of the underlying data and its relationships.^

]]> Fizi Yadav Design and Decorative Arts|Computer Science http://docs.lib.purdue.edu/dissertations/AAI1530481 http://docs.lib.purdue.edu/dissertations/AAI1530481 Wed, 22 May 2013 15:44:38 PDT The Kyoto Protocol has prompted many nations to begin taking steps to reduce the total greenhouse gases they emit. Public opinion has also shifted with respect to nuclear energy. In recent decades, the U.S. government began encouraging and incentivizing the engineering, procurement, and construction of new nuclear power plants through several policy actions. The exorbitant cost of nuclear construction and the daunting regulatory process has slowed down bringing new projects on line; but there are now 12 projects currently under active review by the U.S. Nuclear Regulatory Commission (NRC) that will include up to 20 new nuclear power reactors.^ The U.S. is at the dawn of a "Nuclear Renaissance" that will soon end a 30-year hiatus in the construction of nuclear power plants. The motivation for this resurgence includes environmental stewardship, energy security, and economics. The nuclear construction industry will play a key role in the success or failure in this next generation of nuclear projects. However, many professionals who possess the knowledge and experience of the last generation of nuclear construction projects have retired or will retire soon. Research is therefore crucial in order to retain this past body of knowledge and, most importantly, adapt it to construction techniques and technologies which have become available since the last generation of nuclear power plants were constructed.^ A literature review was conducted in order to assess the overall readiness of the nuclear construction industry for this resurgence and provide recommendations to enhance that readiness in preparation for the next generation of nuclear construction projects. Our areas of focus included human capital readiness, advanced construction technologies, nuclear project lifecycles, past lessons learned, regulations, and safety. The available descriptive statistics provided the relative importance of these various issues; and Importance-Performance Analysis was utilized in order to delineate the potential impact of 70 advanced construction technologies on future nuclear construction projects. Factor analysis was ultimately conducted in order to summarize 76 activities associated with the nuclear project life-cycle into 12 aspects associated with the successful delivery of nuclear construction projects.^ This research identified a shortage of available qualified nuclear construction professionals as well as the nuclear infrastructure to ensure the training and education of new and existing professionals. The findings of this research prompt the development of a nuclear construction body of knowledge (BOK) and the creation of a curriculum in the field of nuclear construction engineering and management. Development of this critical BOK will consider the lessons of past nuclear construction projects, technological developments, and industry evolutions during the 30-year hiatus, as well as provide an innovative vision of the future of nuclear construction. Although many advanced construction technologies are available for deployment on nuclear construction projects, many may not meet the needs of the industry or may be developed beyond the optimal needs of the industry. Careful consideration of the recommended future research would significantly benefit the construction industry in a resurgence of nuclear power projects.^

]]> Erik R Wright Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI1530482 http://docs.lib.purdue.edu/dissertations/AAI1530482 Wed, 22 May 2013 15:44:38 PDT This sensory study evaluated the impact of nutrition labeling on the sensory ratings and intention to purchase a commercial cinnamon coffee cake. The study was conducted in a Sam's Club store and in an atrium of Marriott Hall at Purdue University with 205 participants in the spring of 2012. ^ The cakes were presented under three conditions: no information (control group), information with the "regular fat" product tasted first (original order group) and information with the "low fat" product tasted first (reverse order group). The results indicated there was a generally high acceptance of low fat products and the sensory perception of cakes was robust with regards to the nutrition information except for the children under 10 years of age. Labeling a product low fat will positively impact consumers' stated willingness to purchase the product. This was observed both for males and females, although females tended to be more attentive than males to the nutrition information. In addition, age and gender statistically interacted with each other in influencing consumers' decision making process and this was largely driven by the females' responses. Consumers 18 to 60 years of age showed a positive attitude to using nutrition information while consumers 10 to 17 years of age and consumers above 60 years of age were indifferent to the nutrition information. The decision of children under 10 years of age were influenced by unexpected factors, such as parents' suggestions. Even so, they were more likely to choose the cake labeled regular fat. The findings add complementary value to previous researches in this area and provide theoretical and empirical value to the consumers, restaurateurs, marketers and policy makers.^

]]> Yizhe Xu Agriculture, Food Science and Technology|Health Sciences, Nutrition http://docs.lib.purdue.edu/dissertations/AAI1530479 http://docs.lib.purdue.edu/dissertations/AAI1530479 Wed, 22 May 2013 15:44:37 PDT This thesis looks at the relationship between the addition of various dietary treatments for gastric ulcers and their effects on gastric ulcerations in the esophageal area of the stomach of gestating sows. Other potential effects of the gastric ulceration treatments; gastric pH, salivary pH, heart rate, and oral stereotypies, were also measured.^ In the first study, testing was done to determine the difference in the ability of two oral antacids to increase gastric pH in gilts. Both ranitidine, an H₂-receptor blocker, and omeprazole, a proton-pump inhibitor, were fed to gilts on a rotational schedule while gastric pH was recorded throughout the day. While there was no significant difference in gastric pH when gilts were fed diets with the control diet or omeprazole, the ranitidine diet produced significantly lower gastric pH than the control diet and omeprazole diet. Therefore, the omeprazole may be diet more effective than ranitidine in raising gastric pH and maintaining a higher gastric pH over time in gilts.^ In the second study, gastric ulcer treatments were started at day 30 of gestation and included control, omeprazole, high dietary fiber in the form of 25% soybean hulls, and 2% sodium bicarbonate. These treatments were added to the gestation and lactation diets of pregnant sows and gilts. At day 30, 60, and 90 of gestation, endoscopies were performed on the sows and gilts to determine the levels of gastric ulceration, saliva samples were collected to determine salivary pH, video was recorded to collect data on oral stereotypies, and heart rate was monitored before and after feeding. Endoscopies were also performed on the stomachs of recently slaughtered sows to compare with direct morphological scoring. There were no significant differences in dietary treatment effects on ulceration rate, however, numerically, sows fed the sodium bicarbonate diet did not increase stomach ulcer scores from gestation days 30 to 60, while sows fed the high fiber diet had the least increase in stomach ulcer scores from gestation days 60 to 90. Dietary treatments had no effect on sow behavior with the exception that sows fed sodium bicarbonate had increased water drinking activity. The endoscopy validation performed on the sow stomachs showed moderate agreement between ulcer scores when viewed through an endoscope and examined morphologically. However, the endoscopy consistently uncerscored the ulceration, which could suggest that differences in ulceration in the sows and gilts fed treatment diets may have been larger but due to limitations of the endoscopic examination, these differences were not apparent.^

]]> Stephanie L Wisdom Agriculture, General|Agriculture, Animal Culture and Nutrition|Psychology, Behavioral Sciences http://docs.lib.purdue.edu/dissertations/AAI1530480 http://docs.lib.purdue.edu/dissertations/AAI1530480 Wed, 22 May 2013 15:44:37 PDT Niemann-Pick Type C (NPC) is an autosomal recessive lysosomal storage disorder caused by mutations in one of two genes npc1 or npc2 which encode important cholesterol trafficking proteins (1). Both NPC1 and NPC2 are necessary for the movement of free cholesterol from the late endosomes/lysosomes to the ER where it can be esterified and further modified for biological use. Disruption of cholesterol trafficking leads to build up of cholesterol and other lipids in the late endosomes and lysosomes in all cells of the body (Fig. 1). Patients experience progressive neurodegeneration and liver dysfunction leading to premature death (2).^ 2-hydroxypropyl-β-cyclodextrin (HPβCD) and Miglustat are currently the only FDA approved treatments for this disease, and more treatment options are needed. I used the fluorescent cholesterol analog, dehydroergosterol (DHE) packaged in low-density lipoprotein (DHE-LDL) for easy uptake by cells to monitor cholesterol uptake and storage in a cell culture model of NPC. I found that cells containing NPC1 mutation retained more DHE after 12 hour incubation than wild-type (WT) cells. Moreover, treatment with HPβCD reduces DHE labeling of NPC cells to the level of WT cells. I attempted to use this assay to test several polyrotaxane compounds but found that the drug vehicle, dimethyl sulfoxide, eliminated both differential uptake of DHE and HPβCDs ability to decrease DHE labeling in NPC cells.^

]]> Rachel E Wright Health Sciences, Pharmacology|Health Sciences, General http://docs.lib.purdue.edu/dissertations/AAI1530477 http://docs.lib.purdue.edu/dissertations/AAI1530477 Wed, 22 May 2013 15:44:34 PDT The objective of this research is to determine and analyze the effect a significant change in the speed of reaction (chemical kinetics) has on combustion instability in a single-element rocket combustor. This is carried out using computational fluid dynamics (CFD) and is a continuation of previous work on CFD modeling of combustion instability. Specifically, the goal is to determine whether the combustion will have the same, greater, or less instability with a significant decrease in the speed of reaction in the combustor. Other flow characteristics such as temperature, vorticity, and Rayleigh index are also analyzed and compared with those obtained with the original reaction speed.^ The combustor modeled is a single-element, longitudinal rocket combustor with a choked exhaust nozzle. The fuel is JP-8 and decomposed hydrogen peroxide is used as the oxidizer. The propellants are introduced to the combustion chamber coaxially and are non-premixed. Due to time and computational restraints, a number of simplifications are made to the computational model. These include using 2D axisymmetric modeling, using a single-step global combustion model, and neglecting two-phase effects.^ The results obtained show that the instability is slightly decreased by using the slower chemical kinetics. The results also show that a number of different and often competing phenomena contribute to the instability of the flow. Overall, the large change in chemical kinetics did not have a great effect on the stability of the combustion, although some flow characteristics were greatly changed. This research indicates that there are many contributing factors to combustion instability and the CFD can help in determining which factors are of greatest import for a given combustor.^

]]> Alexander Thomas Whiteman Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI1530478 http://docs.lib.purdue.edu/dissertations/AAI1530478 Wed, 22 May 2013 15:44:34 PDT This study is concerned with understanding the role of the material and the body in communication, explored through a phenomenological study of bike commuters. Through the act of biking to work, bike commuters resist cultural, transportation, and workplace norms. The communication of this resistance takes place primarily through cyclists' bodies, actions, interactions with space, and the material artifacts of biking (i.e., helmets, bike bags, or the bike itself). As bike commuters make themselves present in the space of the road or bring their helmet into their office, they express resistance through material presence. These material and embodied acts also serve as an impetus for discursive resistance as bike commuters' co-workers or neighbors inquire about their activities and initiate conversations. Additionally, bike commuters function as an organization through their collective resistance to transportation norms. However, these cyclists resist being organized as they emphasize the individual nature of their activity.^ This research provides several theoretical contributions. It proposes a rethinking of resistance in which resistive activities need not be planned and intentional, but can occur through mundane and everyday activities. Additionally, the findings suggest that the powerful can resist, challenging that which gives them their legitimacy. Resistance also can be a pleasurable activity, it does not need to be sacrificial. Furthermore, this study suggests a new way of thinking about material and embodied communication, where the material does not need to symbolize something or be spoken through by a human, but can speak for itself. Finally, this research illustrates the hybrid constitution of organizations between human and non-human agents, demonstrating that non-human agents can act in ways contrary to human intentions to form an organization. In addition to these theoretical contributions, this research provides a methodological contribution to the field of communication by introducing a new methodology, video autoethnography, for researching lived experience. This methodology is particularly suitable for studying material and spatial practices that are mobile, but also provides the capability to document experiences from the perspective of the participant, incorporate reflexivity of such experiences, and facilitate the articulation of experience and context in new ways.^

]]> Elizabeth Dorothea Wilhoit Speech Communication|Sociology, Organization Theory http://docs.lib.purdue.edu/dissertations/AAI1530476 http://docs.lib.purdue.edu/dissertations/AAI1530476 Wed, 22 May 2013 15:44:33 PDT Single- and two-phase heat transfer during jet impingement of a perfluorinated dielectric liquid, FC-72, on a silicon test chip is experimentally investigated. Integrated heaters and temperature-sensing diodes in the test chip provide precise heat flux control and local temperature measurements, respectively. A test section is custom-built to determine the effects of nozzle diameter, number of nozzles, ratio of nozzle separation from the surface to nozzle diameter (H/D), and Reynolds number. The number of nozzles investigated ranges from 1 to 121, nozzle diameter ranges from 0.4 mm to 3 mm, and the spacing ratio H/D from 1 to 4. The best performing test case was the 9 × 9 array with D = 0.4 mm and Re = 2000, which was able to dissipate 118 W/cm ² of heat flux during nucleate boiling. Experimental results for single-phase and two-phase heat transfer are compared to predictions from correlations in the literature and show good agreement.^

]]> Don A West Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1530475 http://docs.lib.purdue.edu/dissertations/AAI1530475 Wed, 22 May 2013 15:44:33 PDT Virtual communities and organizations must have members, and leaders, who are trained and prepared to develop informed and creative solutions to globally complex problems. Some previous studies have shown the online virtual world (VW) application known as Second Life (SL) can be engaged as an effective virtual media toward team performance for students while removing the hindrances of lost nuances inherent of other communication technology. It is believed that by engaging students in an immersive three-dimensional (3-D) socialized environment to enhance the educational practice for learners coming out of the digital age, the learning capability of the students will be enriched and supplemented by a more interactive atmosphere. This study analyzes the perceptions of two undergraduate classes toward the introduction and use of virtual media in a large, lecture-formatted classroom environment. As an attempt to provide feedback, without trying to prove or disprove any educational theories, this study hoped to show that virtual media can successfully be employed to supplement the educational experience, enhance class work and learning strategies for the students, and create team/group associations that work efficiently and effectively when students were challenged with real life situations in a virtual environment. Instead, this study found student's generally detested the use of the technology, had a perceived lack of appreciation for the technological advancements in the classroom, and felt forced into participating in the assimilation of the technology or group collaborations whether required of the assignment or not. Perceptually, this study shows it made no difference whether students had any previous experiences with VWs, what their class designation was (freshman, sophomore, etc.), if they were male or female, or their involvement with the VW platform, particularly if they had experience with other VW systems or interactive game settings.^

]]> Amy Caryn Warneka Education, Pedagogy|Education, Adult and Continuing|Education, Higher http://docs.lib.purdue.edu/dissertations/AAI1530474 http://docs.lib.purdue.edu/dissertations/AAI1530474 Wed, 22 May 2013 15:44:32 PDT Over the past ten years, animated films have become increasingly more important to the movie industry. Their increasing popularity is evident when looking at box office hits like Shrek, Kong Fu Panda, and Ice Age, to name a few.^ No one will deny that some animated movies are more attractive to audiences than others. Previous studies show that a film's story is the decisive factor that makes a film a success or a flop. The story plays a central role in bringing in an audience and thus determining a film's critical acclaim and financial success. The story concept ties together various elements that are all closely related and together contribute to the overall effect of an animated film. This research aims to explore the relationship between an animated film's story and its popularity in order to better understand what makes a successful film as well as provide a useful reference for animation studios as they are deciding whether or not to pursue a certain script.^

]]> Meng Wang Cinema http://docs.lib.purdue.edu/dissertations/AAI1530472 http://docs.lib.purdue.edu/dissertations/AAI1530472 Wed, 22 May 2013 15:44:31 PDT Using a qualitative research approach, this study investigated the thoughts and feelings of students regarding the question, "what factors need to be considered when Reverse Engineering (RE) methodology is incorporated into engineering curricula?" The participants in the study were from the Introduction to Graphics for Manufacturing course at the West Lafayette campus of Purdue University. An RE survey was given to the all students enrolled in the course and 10 select students were given the opportunity to use a 3D handheld scanner in a hands-on learning exercise. Each of the 10 students underwent two interviews with questions pertaining to the study, the course, the technology, and the factors they felt were important to RE. The instructor for the course and an industry professional were interviewed to support the data gathered from the student interviews. The outcome of the study was a list of factors that students, the instructor, and the industry professional felt were important to RE implementation. This study provides information important to implementing RE into engineering curricula and suggestions for future research in the field of RE.^

]]> Trevor W Wanamaker Engineering, General http://docs.lib.purdue.edu/dissertations/AAI1530473 http://docs.lib.purdue.edu/dissertations/AAI1530473 Wed, 22 May 2013 15:44:31 PDT The identification of the center of gravity is crucial in determining the behavior and performance of the vehicle, which incorporates handling characteristics and rollover assessment. Conventional methods for locating the center of gravity are either based on labor intensive and subjective static measurements, or enable active road-handling control strategies that are designed for worst case scenarios. Despite the large number of methods that already exist for locating the center of gravity in vehicles, the use of operational data facilely available from measurements, presents a novel approach. This work focused on a near real-time method for identifying the center of gravity of a ground vehicle based solely on a kinematic approach and requires only a few dynamic measurements.^ A theoretical foundation of the method was developed and derived from the translational and rotational aspects of a simplified half-car model. By replacing the restoring forces with the equivalent inertial forces in the analytical model, an expression for the center of gravity was established, which does not explicitly depend on uncertain vehicle parameters. The final development stage of the method averages the extracted pitch motion of the vehicle by evaluating only the acceleration measurements that are opposite in direction to estimate the center of gravity in a ground vehicle. A simulation was conducted to evaluate the performance and robustness of the method by adding unbiased noise to represent more realistic measurements. The method was then demonstrated on a testing vehicle using a two-post vehicle simulator. The accuracy of the estimations proved to be a viable approach for identifying the center of gravity based purely on dynamic responses. Simulated damage and damping conditions on the testing vehicle was experimentally implemented to demonstrate the ability of the method to identify damage influenced by stiffness and damping, including the effects of these damages on the center of gravity.^

]]> Bryan Ye-Wen Wang Engineering, Mechanical http://docs.lib.purdue.edu/dissertations/AAI1530471 http://docs.lib.purdue.edu/dissertations/AAI1530471 Wed, 22 May 2013 15:44:30 PDT The purpose of this research was to evaluate affordable technologies that are capable of providing attractive, cost-effective energy savings to the housing industry. The research did so by investigating the 2011 Solar Decathlon competition, with additional insight from the Purdue INhome. Insight from the Purdue INhome verified the importance of using a three step design process to design a net-zero energy building. In addition, energy consumption values of the INhome were used to compare and contrast different systems used in other houses.^ Evaluation of unbiased competition contests gave a better understanding of how a house can realistically reach net-zero. Upon comparison, off-the-shelf engineering systems such as super-efficient HVAC units, heat pump hot water heaters, and properly designed photovoltaic arrays can affordably enable a house to become net-zero. These important and applicable technologies realized from the Solar Decathlon will reduce the 22 percent of all energy consumed through the residential sector in the United States. In conclusion, affordable net-zero energy buildings can be built today with commitment from design professionals, manufacturers, and home owners.^

]]> Jordan P Wallpe Engineering, General|Sustainability|Energy http://docs.lib.purdue.edu/dissertations/AAI1530470 http://docs.lib.purdue.edu/dissertations/AAI1530470 Wed, 22 May 2013 15:44:30 PDT Global competition and improvements in technology are occurring at speeds never before experienced in human history. Today's organizations are compelled to continually innovate and change or otherwise face the threat of becoming irrelevant or nonexistent. This study uses W. Edwards Deming's System of Profound Knowledge and Brian Joiner's Fourth Generation Management theories as frameworks to explore the effects providing knowledge workers with online training in online collaboration environments has on attitudes, confidence, and willingness to participate.^ The literature review explores the topics of employee empowerment and positive changes in customer satisfaction, organizational quality, and responsiveness. The literature suggest that providing organizational members can improve employee empowerment. Recently eLearning and online collaboration environments have presented very positive opportunities toward the goal of improving employee empowerment.^ This study's key finding is, in brief: knowledge worker's attitudes, confidence, and willingness to participate in online collaboration environments can be positively affected through the administration of online training and simulation towards effective tool use.^

]]> Patrick L Vogt Business Administration, Management|Education, Adult and Continuing http://docs.lib.purdue.edu/dissertations/AAI1530461 http://docs.lib.purdue.edu/dissertations/AAI1530461 Wed, 22 May 2013 15:44:29 PDT The purpose of this qualitative study was to explore the racial identity development of Midwest second-generation Asian Americans in family and school contexts. Six second-generation Asian American college students were interviewed individually. The central phenomenon that emerged was that gender, family and school contexts facilitate the racial identity development for second-generation Asian Americans in the Midwest. Other important themes and subthemes are presented. Implications of the findings and direction for future research are also discussed.^

]]> Xia Hua Asian American Studies|Education, Guidance and Counseling|Psychology, Counseling http://docs.lib.purdue.edu/dissertations/AAI1530454 http://docs.lib.purdue.edu/dissertations/AAI1530454 Wed, 22 May 2013 15:44:29 PDT After fire, water, and mold disasters, archival institutions rely on the restorers responding to moderate and catastrophic disasters. In the absence of the archival staff for reasons including area evacuation, institutional policy, and others, the restorers need knowledge in the training topics found in specific subject matters in order to save the various types of archival materials found in special collections and archives.^ An online survey package was distributed to archival staff and restorers to collect data on ranking importance for a body of knowledge consisting of three subject matters: indoor environment (7), recovery (7), and processing (7). The archival staff (n = 185) and restorers ( n = 52) participated in a two-group study (n = 237). The level of significance was set at p< .05. When archival staff and restorers ranked importance on the 21 training topics for a suggested training program, the groups exhibited statistically significant differences in five training topics. The archival staff found training topics on building triage (for damaged archival materials), controlling ultraviolet light damage, and preventing pest damage more important for restorers to learn prior to entering archival institutions post-disaster. If the restorers gain knowledge on the 21 training topics in the Chart of a Body of Knowledge in Archival Disaster Restoration, then they could fill the knowledge gap highlighted by this study.^

]]> Craig Evans Passley Education, Continuing http://docs.lib.purdue.edu/dissertations/AAI1530419 http://docs.lib.purdue.edu/dissertations/AAI1530419 Wed, 22 May 2013 15:44:28 PDT High tunnels are a form of protected agriculture that aids in season extension by creating a favorable microclimate using trapped solar heat. Tunnel structure is similar to a simple greenhouse, usually comprised of stretched plastic over a large ribbed frame. High tunnels are used extensively around the world for the production of high value crops. In 2010, the USDA-NRCS initiated a high tunnel funding program that aided in the erection of 4,500 new high tunnels across the U.S. in 2010 and 2011. As high tunnel use continues to rise, basic research is needed in this production system to investigate its effectiveness and begin developing specialized IPM solutions to pest-related problems. This study involved production of three crops: tomato, broccoli, and cucumber in three high tunnels as well as three comparison field plots over the 2010 and 2011 growing seasons. Season extension, yield, and fruit quality (size and marketability) were compared among traditional field plots and three different production systems within the tunnels: traditional black plastic mulch, containerized soilless production, and rockwool; however, the rockwool system was quickly abandoned after several failed attempts to maintain plant quality. Season extension was the most dramatic for tomatoes—fruit was harvested in the high tunnels more than two months before the field. Tomato size was also larger in the tunnels and there was a greater percentage of marketable fruit compared to the field. Conversely yield was not significantly different between production systems in the tunnel and the field for tomatoes. There was no significant difference in the broccoli or cucumber size between the high tunnel and the field; however, high tunnel yield was significantly greater for cucumbers and broccoli. There was no significant difference in the cucumber marketability, but broccoli marketability was significantly higher in the field. The containerized soilless production within the tunnel showed no significant advantages--decreased yields, smaller fruit, and lower fruit marketability. Pest density was also compared between the high tunnel and the field. Greenhouse pests were more prevalent in the high tunnels throughout the season. Common field pests such as hornworms and cucumber beetles were not significantly different between the high tunnel and the field; however the crucifer caterpillar complex including imported cabbageworms, diamond back moths, and cabbage loopers was significantly denser within the high tunnels. Multiple insecticide treatments were made in the high tunnels for various pests throughout the season. These results show that pest density is not significantly different in high tunnels compared to the field—implementing integrated pest management techniques is necessary in high tunnels just as it is in the field; however components may need optimized for this specialized form of production. Further research should aid in developing IPM decision making protocols for high tunnel producers.^

]]> Sarah L Thompson Biology, Entomology|Agriculture, Horticulture|Agriculture, General http://docs.lib.purdue.edu/dissertations/AAI1530413 http://docs.lib.purdue.edu/dissertations/AAI1530413 Wed, 22 May 2013 15:44:27 PDT The long term reliability of polymer-based thermal interface materials (TIM) is essential for modern electronic packages which require robust thermal management. The challenge for today's materials scientists and engineers is to maximize the heat flow from integrated circuits through a TIM and out the heat sink. Thermal cycling of the electronic package and non-uniformity in the heat flux with respect to the plan area can lead to void formation and delamination which re-introduces inefficient heat transfer. Measurement and understanding at the nano-scale is essential for TIM development. Finding and documenting the evolution of the defects is dependent upon a full understanding of the thermal probes response to changing environmental conditions and the effects of probe usage. The response of the thermal-displacement measurement technique was dominated by changes to the environment. Accurate measurement of the thermal performance was hindered by the inability to create a model system and control the operating conditions. This research highlights the need for continued study into the probe's thermal and mechanical response using tightly controlled test conditions.^

]]> Jason Scott Steill Nanotechnology|Engineering, Materials Science http://docs.lib.purdue.edu/dissertations/AAI1530342 http://docs.lib.purdue.edu/dissertations/AAI1530342 Wed, 22 May 2013 15:44:26 PDT The purpose of this study was to listen to the voices of Mexican Americans in the Del Paso Heights neighborhood of Sacramento, California in order to understand the their health beliefs regarding diabetes. Utilizing the culture-centered approach (Dutta, 2008) as a conceptual framework, I conducted interviews with eleven Mexican American women and sought to uncover alternative constructions of health meanings located within their lived experiences. This study engaged in dialogue with participants from this minority culture to foreground their voices and to discover the themes that emerge from their stories. The culture-centered approach compelled me, as the researcher, to listen to these voices and acknowledge their expertise in defining health beliefs and identifying structural barriers to pursuing good health. Culture-centered research emphasizes the co-construction of health meanings with cultural participants, which has implications for health communication theory and practice because it offers an alternate perspective to cultural sensitivity approaches, which currently dominates health communication research that deals with culture.^

]]> Kacy Rodriguez Speech Communication|Health Sciences, Public Health|Hispanic American Studies http://docs.lib.purdue.edu/dissertations/AAI1530337 http://docs.lib.purdue.edu/dissertations/AAI1530337 Wed, 22 May 2013 15:44:25 PDT The storage layer is a significant factor in the capital cost, energy cost and performance of servers and data-centers. Emerging high-performance, low-energy, non-volatile, solid-state storage media show enormous potential to solve the storage performance and energy problems. However, the high cost-per-byte of solid-state media has hindered wide-spread adoption in servers. Thus we propose a new, cost-effective architecture - SieveStore - that enables the use of solid-state media to significantly filter access to storage ensembles. This work makes three key contributions. First, we make the case for highly-selective, storage-ensemble-level disk-block caching based on our observations that block accesses of storage ensembles exhibit extremely skewed popularity, and though the degree of skew for the ensemble as a whole remains invariant, the popular block set is dynamic across storage volumes of both the same and different servers, and in time for the same server. Second, we show that selective cache allocation - sieving - fundamentally enables efficient ensemble-level disk-caching. Third, we propose two variants of SieveStore. The first variant SieveStore-D) selectively batch-allocates cache space at discrete time-intervals. The second variant (SieveStore-C) allocates cache space continuously via a hysteresis-based, lazy allocation policy. Based on traces from a storage ensemble representing the block accesses of 13-servers, over a period of one week, we find that sieving and ensemble-level caching each contribute to SieveStore's cost-effectiveness. Both variants of SieveStore achieve significantly higher hit ratios than unsieved ensemble-level disk-caching (35%-50% more, on average) while using only 1/7^th the number of SSD drives. Further, ensemble-level caching is a strictly superior cost-performance point compared to per-server caching.^

]]> Timothy A Pritchett Engineering, Computer|Computer Science http://docs.lib.purdue.edu/dissertations/AAI1530339 http://docs.lib.purdue.edu/dissertations/AAI1530339 Wed, 22 May 2013 15:44:25 PDT Erosive effects in Polybutadiene Acyrlonitrile and Hydroxyl Terminated Polybutadiene based composite propellants are investigated using a planar geometry combustor. An adjustable port-to-throat area ratio allows high and low port Mach numbers to be evaluated at multiple pressures. Head, mid, and aft motor pressure instrumentation as well as aft burning rate measurements using an ultrasonic transducer provide the necessary information about the operation of the motor. Erosive burning was studied using the classical Lenoir Robillard model, a modified form of Dickenson's model, the Thompson McClure model, and the Saderholm model. Erosive burning parameter estimates were made by fitting to an inferred burning rate based upon pressure measurements and by matching to pressure reconstructions. The experiment covers chamber conditions ranging from 300 psi to 700 psi and port Mach numbers from 0.1 to 0.7. Data and reconstructions of 8 tests are included and indicate that the Lenoir Robillard model is best suited of the models considered to estimate erosive burning using inferred burning rate alone. In addition, no significant differences were observed in regards to erosive burning for the PBAN and HTPB propellants studied herein.^

]]> Andrew Karl Rettenmaier Engineering, Aerospace http://docs.lib.purdue.edu/dissertations/AAI1530318 http://docs.lib.purdue.edu/dissertations/AAI1530318 Wed, 22 May 2013 15:44:24 PDT The purpose of this study was to explore the ways school counselors are supporting students from military families with deployed or deploying parents in terms of emotional, behavioral, academic, and psychosocial support, as well as the methods used for identifying this student population at school. Seventy-seven professional school counselors from the state of Indiana participated in the study by answering the researcher-created survey, Identifying and Supporting Military Students Descriptive Questionnaire. The discussion includes best practice interventions being used, areas for future professional development, methods and responsibility for identifying students from military families, and school counselor awareness and support for this student population. Implications of the study and directions for future research are also discussed.^

]]> Courtney Marie Oliver Education, Guidance and Counseling http://docs.lib.purdue.edu/dissertations/AAI1530306 http://docs.lib.purdue.edu/dissertations/AAI1530306 Wed, 22 May 2013 15:44:23 PDT This research was conducted to provide greater depth into the ability of STEP AP 203 Edition 2, JT, and 3D PDF to translate and preserve information while using a benchmark model. The benchmark model was designed based on four industry models and created natively in the five industry leading 3D CAD programs. The native CAD program models were translated using STEP, JT, and 3D PDF. Several criteria were analyzed along the paths of translation from one disparate CAD program to another. Along with the analysis of the three interoperable file formats a survey was conducted to determine how well the benchmark model captures what is used in industry and whether a benchmark model could be used for an industry or company. Several industry experts participated in the survey to determine what important criteria does a potential benchmark model need to capture. The conclusions of the research show that neither interoperable file format out-performs the other for a majority of the analysis criteria. The survey suggests that a benchmark model could be used in an industry or company and the general structure of this benchmark.^

]]> Dillon McKenzie-Veal Engineering, Computer|Computer Science http://docs.lib.purdue.edu/dissertations/AAI1529917 http://docs.lib.purdue.edu/dissertations/AAI1529917 Wed, 22 May 2013 15:44:20 PDT The purpose of this thesis was to examine the moderating effects positive sibling relationships have on an individual's differentiation and romantic relationship satisfaction when having witnessed Intimate Partner Violence (IPV) as a child. There has been a significant amount of research related to the negative effects of IPV but little on what may reduce some of the negative outcomes. ^ To gather the data, the researcher administered a questionnaire to individuals 18 years and older who had at least one sibling and had been in a romantic relationship at for at least 6 months when completing the survey ( N = 238). The survey included questions related to sibling relationships, the individual's current romantic relationship, differentiation, and violence or conflict that was witnessed as a child, as well as several demographic questions. ^ The results of this study demonstrated that sibling relationships had an effect on individuals who have witnessed IPV, although not always having a moderation effect. These results indicate the need for continued research on the effects of sibling relationships. The study also found a single item measuring the frequency of witnessing parental conflict and disagreements that was more predictive of differentiation and romantic relationship satisfaction than an 8-item measure. This may signify the need to examine the types of negative interactions children witness more carefully to determine the effects. This information can be used in relation to treatment as well as to help establish preventative strategies that may be used by clinicians to treat this population. ^

]]> Hillary Paige Rawlings Health Sciences, Mental Health|Psychology, Behavioral|Psychology, Developmental http://docs.lib.purdue.edu/dissertations/AAI1529854 http://docs.lib.purdue.edu/dissertations/AAI1529854 Wed, 22 May 2013 15:44:18 PDT Bolt-A-Blok system is a unitized, post-tensioned, structural system comprised of concrete blocks, tensioned steel bolts, and bars, eliminating the need for traditional mortar. This thesis presents a refined procedure to calculate the flexural capacity of the Blot-A-Blok wall system based on results of construction tests. The objective is to develop an analysis procedure to determine strain in the bolts, and as a result, the stress in bolts at failure. Flexural capacities computed using the assumptions of bonded connections are compared with test results and with strength calculations performed by a researcher at Pennsylvania State University. Applications of the proposed method include design of residential basement walls and other simply supported walls, such as those used in "big-box" stores.^

]]> Yuxing Yang Engineering, Civil http://docs.lib.purdue.edu/dissertations/AAI1529855 http://docs.lib.purdue.edu/dissertations/AAI1529855 Wed, 22 May 2013 15:44:18 PDT Globalization and environmental problems have drawn attention to hotel operations around the world. In response to those and other reasons including cost reducing and philanthropy, hotels have adopted a variety of socially responsible activities. Previous research of Corporate Social Responsibility (CSR) in the hotel industry has centered on Western countries since CSR is commonly regarded as a Western value. Little information about CSR has been disclosed in relation to the Chinese hotel industry. The aim of the present study attempts to examine dominant CSR practices in Chinese hotel industry and how hotel managers perceive the concept of CSR. Since traditional Chinese values share many common values with CSR, the present study also attempts to understand if those traditional Chinese values influence hotel managers' perspectives of CSR. ^ After conducting 17 in-depth interviews with Chinese hotel managers, the present study's results indicate that Chinese hotels have been working on various CSR activities, but they rarely promote those practices to the public. Smaller hotels seldom engage in CSR practices because of low profits. Among the hotels that have conducted various CSR activities, most managers believe that human nature or inner desire is the major motivation to commit to CSR. Benefits, long-term development, and other reasons are secondary motivations. The study's results also show that traditional Chinese values have significant influence on managers' perspectives towards CSR. The teachings of Confucianism have been the prevalent traditional value that influence managers' perspectives. Detailed results will be discussed in Chapter 5.^

]]> Chan Yu Business Administration, Management http://docs.lib.purdue.edu/dissertations/AAI1529852 http://docs.lib.purdue.edu/dissertations/AAI1529852 Wed, 22 May 2013 15:44:17 PDT World literature, according to David Damrosch, is "writing that gains in translation" (288). Literary texts, unlike informative texts, either gain or lose in translation. A text that gains can have a life beyond national literature. For students, world literature often consists of texts listed on the syllabi. The study of world literature, therefore, inevitably faces a number of issues regarding translation and text selection. ^ While ideally everyone should learn more languages, in practice we are often limited by our own knowledge, both linguistically and culturally. Scholars have cautioned us that comparative reading can often miss the real complexity and peculiarity of a work in favor of the so called universalities. Some even go as far as claiming comparison as violence against the other. However, to discard comparison as a whole would be counter-productive. ^ There are different ways to teach world literature. What is important, especially given the declining desire to read among students these days, is to find an approach that helps the student develop a spontaneous response, foster an interest and form a habit of reading. In this thesis, I use one topic, namely the father-son relationship, to tie together a group of texts ranging from Ancient Greek epics to young adult novels, and try to examine how that often problematic relationship is depicted by various authors from different areas and time periods, in the hope that a readily accessible topic like this would generate the students' interest and provide them with a starting point for further discussions.^

]]> Bing Yan Literature, Comparative http://docs.lib.purdue.edu/dissertations/AAI1529853 http://docs.lib.purdue.edu/dissertations/AAI1529853 Wed, 22 May 2013 15:44:17 PDT Multiple sclerosis (MS) is a severe neurodegenerative disease signified by motor impairment caused by conduction block of demyelinated axons in the central nervous system. The mechanism of axonal conduction loss is believed to be largely due to the exposure of potassium channels resulting from myelin damage and increasing outward current. Consistent with this notion, potassium channel blockers are known for restoring conduction in the demyelinated axons. Consequently, such treatment has been identified as a key therapeutic strategy to restore function in MS. ^ In the current study, we have established an ex vivo rat spinal cord axonal demyelination model produced by acute exposure of acrolein which has been linked to myelin damage in MS. Using a well-established double sucrose gap recording system, acrolein was applied to isolated strips of spinal cord to induce acrolein-mediated functional loss by monitoring compound action potential (CAP) conductance. The current study demonstrates that acrolein can lead to the reduction of CAP amplitudes, providing direct evidence supporting the role of acrolein in spinal cord injury. We also confirm the acrolein-mediated myelin damage via morphological evaluation such as plastic section taken from the acrolein-exposed spinal cord. ^ We have further shown that a novel potassium channel blocker, 4-AP-3-MeOH can restore axonal conduction in acrolein-damaged axons due to the enhancement of CAP. The degree of improvement in axonal conduction by 4-AP-3-MeOH is significant and comparable to that induced by the bench mark potassium channel blocker 4-AP in similar preparation. While 4-AP is an FDA-approved medication to improve walking ability in MS patients, its narrow therapeutic range and significant side effects limit its effectiveness in clinical application. Previous studies have indicated that unlike 4-AP, 4-AP-3-MeOH can restore axonal conduction without adversely changing electrophysiological properties. In addition, 4-AP-3-MeOH is 10 times more potent than 4-AP in restoring axonal conduction. Therefore, 4-AP-3-MeOH is likely a viable alternative for MS patients in which 4-AP treatment is ineffective.^

]]> Rui Yan Biology, Neuroscience http://docs.lib.purdue.edu/dissertations/AAI1529850 http://docs.lib.purdue.edu/dissertations/AAI1529850 Wed, 22 May 2013 15:44:16 PDT The focus of this work is on the prosodic acquisition of native Deaf children acquiring American Sign Language (ASL). Discussion of the acquisition is centered on prosodic elements: phrase-final sign duration lengthening, phrase-final transition duration lengthening, blinks, eyebrow behavior, head tilts, body tilts, and drop hands. Data was acquired from four adult signers, five older children (7;8-8;5) and two younger children (5;0-5;3) naturally acquiring ASL. The task was to retell, in ASL, a Sylvester and Tweety cartoon. ^ The results demonstrate that there is a varied profile of acquisition across th