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"Independent Original and Progressive": Celebrating 125 Years of UNT
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Joshua C. Chilton first described UNT as “independent, original and progressive” in his inaugural speech opening the university in 1890. In the 125 years since then the university has more than lived up to his expectations. The University Archive holds countless photographs, artifacts and publications which tell the remarkable story of UNT from its beginnings in a downtown hardware store to its place today as the one of the nation’s largest public universities. This book features stories about the people and events that helped to define the character and spirit of UNT. Each story is illustrated with photographs and artifacts specially chosen from the Special Collections department and the Music Library, both part of the UNT Libraries, whose staff are proud to share these wonderful memories with you.​ digital.library.unt.edu/ark:/67531/metadc850080/
The UNT Music Library at 75: Selections from Its Special Collections
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The UNT Music Library boasts an interesting and vastly varied assortment of musical treasures in its special collections. This commemorative volume celebrates its 75th anniversary with a brief history of the Music Library and a selection of items from its unique collections. digital.library.unt.edu/ark:/67531/metadc850081/
Medical comorbidity in the course of bipolar disorder.
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Bipolar disorder is a serious illness affecting approximately 2-4% of the population and is one of the world’s leading causes of disability. In individuals with bipolar disorder, medical comorbidity associated with cardiovascular, respiratory and endocrine disorders is related to increased rates of mortality. Recent updates to multi-system inflammatory related conceptualizations of bipolar disorder focus on the unique power that medical illness and biological processes may play as factors associated with course and outcome in bipolar disorder. The current study examined medical comorbidity and its associations with various demographic and psychological variables in individuals with bipolar disorder, schizophrenia, and major depressive disorder with psychotic features followed for 10 years from their first hospital admission. When compared to an age, gender and race-matched control sample from the population, those with bipolar disorder had significantly higher medical comorbidity across a range of medical diagnoses both at 6 months and 10 years after first hospital admission. Ten years following initial hospitalization, individuals in all three diagnostic groups reported increased rates of diabetes (OR: 2.0 – 3.7), stroke (OR: 4.6 – 7.0) and asthma (OR: 1.9 - 3.1), and individuals with bipolar disorder reported increased rates of cancer (OR = 2.1). A number of psychological and demographic symptoms were examined for their ability to predict the development of medical illness across the assessment interval. Overall rates of medical illness were elevated both early in illness course and 10 years after diagnosis, suggesting that broad sequelae of multi-system inflammation are present early and progress over time. digital.library.unt.edu/ark:/67531/metadc849606/
Microstructural Phase Evolution In Laser Deposited Compositionally Graded Titanium-Chromium Alloys
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A compositionally graded Ti-xCr (10≤x≤30 wt%) alloy has been fabricated using Laser Engineered Net Shaping (LENSTM) to study the microstructural phase evolution along a compositional gradient in both as-deposited and heat treated conditions (1000°C followed by furnace cooling or air cooling). The alloys were characterized by SEM BSE imaging, XRD, EBSD, TEM and micro-hardness measurements to determine processing-structure-property relations. For the as-deposited alloy, α-Ti, β-Ti, and TiCr2 (C15 Laves) phases exist in varying phase fractions, which were influential in determining hardness values. With the furnace cooled alloy, there was more homogeneous nucleation of α phase throughout the sample with a larger phase fraction of TiCr2 resulting in increased hardness values. When compared to the air cooled alloy, there was absence of wide scale nucleation of α phase and formation of ω phase within the β phase due to the quicker cooling from elevated temperature. At lower concentrations of Cr, the kinetics resulted in a diffusionless phase transformation of ω phase with increased hardness and a lower phase fraction of TiCr2. In contrast at higher Cr concentrations, α phase separation reaction occurs where the β phase is spinodally decomposed to Cr solute-lean β1 and solute-rich β2 resulting in reduced hardness. digital.library.unt.edu/ark:/67531/metadc849610/
Inter
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This dissertation is has two parts: a critical essay on the lyric subject, and a collection of poems. In the essay, I suggest that, contrary to various anti-subjectivists who continue to define the lyric subject in Romantic terms, a strain of Post-Romantic lyric subjectivity allows us to think more in terms of space, process, and dialogue and less in terms of identity, (mere self-) expression, and dialectic. The view I propose understands the contemporary lyric subject as a confluence or parallax of imagined and felt subjectivities in which the subject who writes the poem, the subject personified as speaker in the text itself, and the subject who receives the poem as a reader are each repeatedly drawn out of themselves, into others, and into an otherness that calls one beyond identity, mastery, and understanding. Rather than arguing for the lyric subject as autonomous, expressive (if fictive) "I,” I have suggested that the lyric subject is a dialogical matrix of multiple subjectivities—actual, imagined, anticipated, deferred—that at once posit and emerge from a space whose only grounded, actual place in the world is the text: not the court, not the market, and not a canon of legitimized authors, but in the relatively fugitive realm of text. In this way, there is no real contradiction between what Tucker terms the intersubjective and the intertextual. The lyric space I am arguing for is ultimately a diachronic process in which readers take up the poem and bring that space partially into their bodies, imaginations, and consciousness even as the poem brings them out, or to the edge, of each of these. digital.library.unt.edu/ark:/67531/metadc849627/
Thermomechanical processing, additive manufacturing and alloy design of high strength Mg alloys.
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The recent emphasis on magnesium alloys can be appreciated by following the research push from several agencies, universities and editorial efforts. With a density equal to two-thirds of Al and one-thirds of steel, Mg provides the best opportunity for lightweighting of metallic components. However, one key bottleneck restricting its insertion into industrial applications is low strength values. In this respect, Mg-Y-Nd alloys have been promising due to their ability to form strengthening precipitates on the prismatic plane. However, if the strength is compared to Al alloys, these alloys are not attractive. The primary reason for low structural performance in Mg is related to low alloying and microstructural efficiency. In this dissertation, these terminologies are discussed in detail. A simple calculation showed that the microstructural efficiency in Mg-4Y-3Nd alloy is 30% of its maximum potential. Guided by the definitions of alloying and microstructural efficiency, the two prime objectives of this thesis were to: (i) to use thermomechanical processing routes to tailor the microstructure and achieve high strength in an Mg-4Y-3Nd alloy, and (ii) optimize the alloy chemistry of the Mg-rare earth alloy and design a novel rare—earth free Mg alloy by Calphad approach to achieve a strength of 500 MPa. Experimental, theoretical and computational approaches have been used to establish the process-structure-property relationships in an Mg-4Y-3Nd alloy. For example, increase in strength was observed after post aging of the friction stir processed/additive manufactured microstructure. This was attributed to the dissolution of Mg2Y particles which increased the alloying and microstructural efficiency. Further quantification by numerical modeling showed that the effective diffusivity during friction stir processing and friction stir welding is 60 times faster than in the absence of concurrent deformation leading to the dissolution of thermally stable particles. In addition, the investigation on the interaction between dislocations and strengthening precipitate revealed that, specific defects like the I1 fault aid in the accelerated precipitation of the strengthening precipitate in an Mg-4Y-3Nd alloy. Also, the effect of external field (ultrasonic waves) was studied in detail and showed accelerated age hardening response in Mg-4Y-3Nd alloy by a factor of 24. As the bottleneck of low strength is addressed, the answers to the following questions are discussed in this dissertation: What are the fundamental micro-mechanisms governing second phase evolution in an Mg-4Y-3Nd alloy? What is the mechanical response of different microstructural states obtained by hot rolling, friction stir processing and friction stir additive manufacturing? Is defect engineering critical to achieve high strength Mg alloys? Can application of an external field influence the age hardening response in an Mg-4Y-3Nd alloy? Can a combination of innovative processing for tailoring microstructures and computational alloy design lead to new and effective paths for application of magnesium alloys? digital.library.unt.edu/ark:/67531/metadc849628/
Investigation of the effect of particle size and particle loading on thermal conductivity and dielectric strength of thermoset polymers.
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Semiconductor die attach materials for high voltage, high reliability analog devices require high thermal conductivity and retention of dielectric strength. A comparative study of effective thermal conductivity and dielectric strength of selected thermoset/ceramic composites was conducted to determine the effect of ceramic particle size and ceramic particle loading on thermoset polymers. The polymer chosen for this study is bismaleimide, a common aerospace material chosen for its strength and thermal stability. The reinforcing material chosen for this study is a ceramic, hexagonal boron nitride. Thermal conductivity and dielectric breakdown strength are measured in low and high concentrations of hexagonal boron nitride. Adhesive fracture toughness of the composite is evaluated on copper to determine the composite’s adhesive qualities. SEM imaging of composite cross-sections is used to visualize particle orientation within the matrix. Micro-indentation is used to measure mechanical properties of the composites which display increased mechanical performance in loading beyond the percolation threshold of the material. Thermal conductivity of the base polymer increases by a factor of 50 in 80%wt loading of 50µm hBN accompanied by a 10% increase in composite dielectric strength. A relationship between particle size and effective thermal conductivity is established through comparison of experimental data with an empirical model of effective thermal conductivity of composite materials. digital.library.unt.edu/ark:/67531/metadc849629/
With the Earth in Mind: Ecological Grief in the Contemporary American Novel
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"With the Earth in Mind" responds to some of the most cutting-edge research in the field of ecocriticism, which centers on ecological loss and the grief that ensues. Ecocritics argue that ecological objects of loss abound--for instance, species are disappearing and landscapes are becoming increasingly compromised--and yet, such loss is often deemed "ungrievable." While humans regularly grieve human losses, we understand very little about how to genuinely grieve the loss of nonhuman being, natural environments, and ecological processes. My dissertation calls attention to our society's tendency to participate in superficial nature-nostalgia, rather than active and engaged environmental mourning, and ultimately activism. Herein, I investigate how an array of postwar and contemporary American novels represent a complex relationship between environmental degradation and mental illness. Literature, I suggest, is crucial to investigations of this problem because it can reveal the human consequences of ecological loss in a way that is unavailable to political, philosophical, scientific, and even psychological discourse. digital.library.unt.edu/ark:/67531/metadc849760/
Adhesion and Surface Energy Profiles of Large-area Atomic Layers of Two-dimensional MoS2 on Rigid Substrates by Facile Methods
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Two-dimensional (2D) transition metal dichalcogenides (TMDs) show great potential for the future electronics, optoelectronics and energy applications. But, the studies unveiling their interactions with the host substrates are sparse and limits their practical use for real device applications. We report the facile nano-scratch method to determine the adhesion energy of the wafer scale MoS2 atomic layers attached to the SiO2/Si and sapphire substrates. The practical adhesion energy of monolayer MoS2 on the SiO2/Si substrate is 7.78 J/m2. The practical adhesion energy was found to be an increasing function of the MoS2 thickness. Unlike SiO2/Si substrates, MoS2 films grown on the sapphire possess higher bonding energy, which is attributed to the defect-free growth and less number of grain boundaries, as well as less stress and strain stored at the interface owing to the similarity of Thermal Expansion Coefficient (TEC) between MoS2 films and sapphire substrate. Furthermore, we calculated the surface free energy of 2D MoS2 by the facile contact angle measurements and Neumann model fitting. A surface free energy ~85.3 mJ/m2 in few layers thick MoS2 manifests the hydrophilic nature of 2D MoS2. The high surface energy of MoS2 helps explain the good bonding strength at MoS2/substrate interface. This simple adhesion energy and surface energy measurement methodology could further apply to other TMDs for their widespread use. digital.library.unt.edu/ark:/67531/metadc849762/
Development of an Instrument to Measure the Level of Acceptability and Tolerability of Cyber Aggression: Mixed-Methods Research on Saudi Arabian Social Media Users
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Cyber aggression came about as a result of advances in information communication technology and the aggressive usage of the technology in real life. Cyber aggression can take on many forms and facets. However, the main focus of this study is cyberbullying and cyberstalking through information sharing practices that might constitute digital aggressive acts. Human aggression has been extensively investigated. Studies focusing on understanding the causes and effects that can lead to physical and digital aggression have shown the prevalence of cyber aggression in different settings. Moreover, these studies have shown strong relationship between cyber aggression and the physiological and physical trauma on both perpetrators and their victims. Nevertheless, the literature shows a lack of studies that could measure the level of acceptance and tolerance of these dangerous digital acts. This study is divided into two main stages; Stage one is a qualitative pilot study carried out to explore the concept of cyber aggression and its existence in Saudi Arabia. In-depth interviews were conducted with 14 Saudi social media users to collect understanding and meanings of cyber aggression. The researcher followed the Colaizzi’s methods to analyze the descriptive data. A proposed model was generated to describe cyber aggression in social media applications. The results showed that there is a level of acceptance to some cyber aggression acts due to a number of factors. The second stage of the study is focused on developing scales with reliable items that could determine acceptability and tolerability of cyber aggression. In this second stage, the researcher used the factors discovered during the first stage as source to create the scales’ items. The proposed methods and scales were analyzed and tested to increase reliability as indicated by the Cronbach’s Alpha value. The scales were designed to measure how acceptable and tolerable is cyber-bullying, cyber-stalking in Saudi Arabia and the sharing of some information in social media applications. The results show a strong tolerance level of those activities. This study is a valuable resource for advanced-level students, educators, and researchers who focus on cyber security, cyber psychology, and cyber aggression in social network sites. digital.library.unt.edu/ark:/67531/metadc849766/
A Phenomenology of Fostering Learning: Alternate Reality Games and Transmedia Storytelling
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This dissertation presents the essence of the experience of instructional designers and instructors who have used alternate reality games (ARGs) and transmedia storytelling (TS) for teaching and learning. The use of game-like narratives, such as ARGs and TS, is slowly increasing. However, we know little about the lived experiences of those who have implemented such transmedia experiences in formal or informal learning. The data consists of written transcripts from interviews with 11 co-researchers in the United States and Europe. Phenomenology was the guiding methodology. The study begins by reviewing storytelling and the use of games in learning, leading up to exploring the tradition of using ARGs and TS in learning contexts. The analysis was one of reduction leading to codes, summary stories, themes, and the essence of the experience. Co-researchers used many techniques to enlighten their learners including problem-solving, critical thinking, collaboration, encouragement, disruption, and connection-making. When successful, connection-making facilitates learner agency development by providing learners with the power to act by their own initiative. Action came through the communicated narratives and games that closely tied to real-world problems. In the context of these efforts, this study's co-researchers emerged as educational life-world learning-coaches, "sensei", who were each using strategies and techniques to move students toward meaningful real-world learning and the ability to make a difference in the world. The dissertation closes by exploring implications of this study for instructional designers and instructors interested in using alternate reality games and transmedia storytelling for teaching and learning purposes. digital.library.unt.edu/ark:/67531/metadc849769/
Predicting Posttraumatic Stress Disorder Symptoms During Adolescence: A Longitudinal Study of The Role of Hypothalamic-Pituitary-Adrenal (HPA) Axis Dysfunction
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Posttraumatic stress disorder (PTSD) is a trauma-related disorder that may develop in response to traumatic or stressful events. Dysfunction of the Hypothalamic-Pituitary-Adrenal (HPA) axis has been implicated in the disorder. Studies support such dysfunction as being a consequence of PTSD, rather than a precursor. However, most studies of the HPA are either cross-sectional or have been carried out in adults. The aim of the present study was to identify whether HPA dysregulation interacts with stressful experiences to increase the likelihood of developing PTSD symptoms in a community-recruited sample of healthy adolescent girls. Adolescent girls (N = 550) and one of their parents participated. Adolescents’ clinical symptoms were assessed at baseline and at a nine month follow-up. Saliva samples were collected from all adolescent participants at waking, 30 minutes after waking, and 8 pm on 3 consecutive days. Flattened diurnal slope of cortisol at baseline was associated with increased PTSD symptoms nine months later. Baseline cortisol awakening response (CAR) per se was not prospectively related to developing PTSD symptoms, but its interactions with stressful experience was associated with elevated PTSD symptoms at follow-up. Effects were small and need to be replicated in samples with more severe stressors, as well as more clinical levels of PTSD. Nevertheless, findings suggest that dysregulated basal HPA functioning may be involved in the development of PTSD symptoms. digital.library.unt.edu/ark:/67531/metadc849771/
Accelerated Corrosion Test with Operation Simulation of All-Aluminum Microchannel Heat Exchangers
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The HVAC&R industry is looking to transition from copper-aluminum heat exchangers to all-aluminum microchannel technology. The want for the transition stemmed from seeing the performance improvement of all-aluminum microchannel radiators in the automotive industry. Applications differ between the two industries; therefore, applying this technology for HVAC&R use must be validated. Research towards operating modes of an all-aluminum heat exchanger in a defined corrosive environment will provide the industry with a better understanding of heat exchanger design and heat exchanger material selection. The worth in this is preventing overdesign and producing more efficient heat exchangers. Furthermore, ASHRAE members and the corrosion community will find value in a defined corrosion system and corrosion test procedure. The information gained through past research has progressed assessment of material performance; however, the methods improperly simulate and expedite natural weathering. The most common method being used is the ASTM (American Society of Testing Materials) Sea Water Acetic Acid Test. The research discussed in this paper was focused on improving a standard corrosion system by implementing system modifications to simulate heat exchanger operation while performing a modified wet-dry cyclic test (e.g. ASTM G85 Annex 5). The goal is to produce results that are more representative of natural corrosion behavior and its forms. Current results were gathered from five of ten samples that underwent initial testing. Finally, possible improvements towards the chamber system and the test method, including the salt solution, are discussed. digital.library.unt.edu/ark:/67531/metadc849775/
Role of Combat Exposure and Insomnia in Student Veterans' Adaptation to College
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Since 2002, the number of veterans enrolled in universities has nearly doubled, although 30-40% of veterans fail to complete their degree. While research efforts to understand the challenges veterans face transitioning from military life to college has increased in recent years, few studies have looked beyond the effects of post-traumatic stress disorder (PTSD). Insomnia is the most frequently reported symptom of combat veterans and can have serious implications for college students. The purpose of this study was to examine the role of insomnia and student veteran adaptation to college relative to civilian students. College students (N = 588) were administered a Background Information Questionnaire, the Insomnia Severity Index, the Deployment Risk and Resilience Inventory, and the Student Adaptation to College Questionnaire. Results revealed that students with insomnia reported significantly lower adaptation to college than students without insomnia. Student veterans reported better academic and personal-emotional adaptation to college than civilian students, while civilians reported better social adjustment than veterans. Although combat veterans without insomnia scored consistently higher academic adjustment than non-combat veterans and civilian students, when present insomnia seemed to have a greater negative effect on combat veterans’ academic adjustment relative to civilian students. Furthermore, insomnia mediated the relationship between combat exposure and veteran’s personal-emotional adjustment to college. Implications and future directions for research are discussed. digital.library.unt.edu/ark:/67531/metadc849743/
Quality Management Theory Development and Investigation of the Constructs within an Organizational Framework
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Supply chain management (SCM) and quality management (QM) share some common literature and have overlapping domains that reinforce each other in the supplier and customer relationship management areas. Despite the recognized importance of supplier and customer relationships toward achieving quality goals, limited prior research examines whether SCM represents a distinct construct within the prominent existing quality focused organizational frameworks such as the Malcolm Baldrige National Quality Award (MBNQA). As a result of the absence of the SCM construct in the frameworks, the problem facing researchers is understanding the role of SCM in the implementation of QM practices within an organization. Such an understanding is key to QM theory development for the 21st century organizations. In order to conduct this investigation, we examine several well-studied quality focused organizational frameworks that are validated among the community of researchers, and, widely accepted among practitioners. However, which of these well-known quality management models serve as the best proxy for a quality focused organizational framework is an important area for research in order to better promote QM worldwide. This research involves three essays and uses a mixed methodology of qualitative and quantitative research. Essay 1 compares well-known national quality award frameworks such as the MBNQA, the Deming Prize, and the European Foundation for Quality Management (EFQM) Award through analysis of the extensive literature on each as well as examination of the government documents about the frameworks. Comparisons show the Baldrige framework most widely serves as basic model for national quality award frameworks to increase the awareness of quality and promote the best QM practices. After reviewing the categories and their weightings in the frameworks of MBNQA, the Deming Prize, and the EFQM Award, we identify opportunities to refine the frameworks and promote QM theory development. Essay 2 fills a critical research gap by assessing the effectiveness of the Baldrige framework within a government organization and by comparing the effectiveness of the categories of the Baldrige framework in government to the effectiveness of the categories in different industries. This study examines the relative effectiveness of each Baldrige category in the MBNQA 2013-2014 framework using data from a municipal government. It tests the hypothesized research model employing partial least squares - structural equation modeling (PLS-SEM). Drawing on contingency theory, it explores the commonalities and differences of the effectiveness of Baldrige categories across different industries by comparing our results with summarized prior research findings of interrelationships among the Baldrige categories. Essay 3 posits a restructured Baldrige framework after conducting a rigorous literature review on SCM and examining the Baldrige framework and categories associated with SCM. This work includes a longitudinal set of studies that test the hypothesized research model based upon the newly posited restructured theoretical framework using PLS-SEM on survey data from three different time periods over 20 years across a variety of organizations. The results support that the restructured framework provides a good model fit when the SCM construct is independently identified and included within the framework. The comparison from the longitudinal analysis provides significant insights for theory evolutions of leadership, SCM, and information systems constructs. Additionally, this longitudinal investigation over 20 years supports the evolution of the Baldrige framework as it was revised over time. Most importantly the work posits and supports the new theory development and shows the overarching importance of the SCM as a major organizational construct. digital.library.unt.edu/ark:/67531/metadc849744/
Eaten: A Novel
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This novel operates on two levels. First, it is a story concerning the fate of a young woman named Raven Adams, who is prompted into journeying westward after witnessing what she believes to be an omen. On another level, however, the novel is intended to be a philosophical questioning of western modes of “science-based” singular conceptualizations of reality, which argue that there is only one “real world” and anyone who deviates from this is “crazy,” “stupid,” or “wrong.” Raven as a character sees the world in terms of what might be called “magical thinking” in modern psychology; her closest relationship is with a living embodiment of a story, the ancient philosopher Diogenes, which she believes is capable of possessing others and directing her journey. As the story continues the reader comes to understand Raven’s perceptions of her reality, leading to a conceptualization of reality as being “multi-layered.” Eventually these layers are collapsed and unified in the final chapters. The novel makes use of many reference points including philosophy, classical mythology, folklore, religion, and internet social media in order to guide the reader along Raven’s story. digital.library.unt.edu/ark:/67531/metadc849746/
Quantum Coherent Control and Propagation in Lambda System
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Strong coherence in quasi-resonant laser driven system interferes with effective relaxations, resulting in behaviors like, coherent population trapping and Electromagnetically induced transparency. The Raman system can optimize this utilizing excited coherence in the lambda system when exposed to counter- intuitive pump-stokes pulses. The phenomenon can result in complete population transfer between vibrational levels called Stimulated Raman adiabatic passage(STIRAP). STIRAP and CHIRAP have been studied with Gaussian and chirped pulses. The optical propagation effects in dense medium for these phenomenon is studied to calculate the limitations and induced coherences. Further, the effect of rotational levels has been investigated. The molecular vibrational coherence strongly depends on the effect of rotational levels. The change in coherence interaction for ro-vibrational levels are reported and explained. We have considered the effects on the phase of radiation related to rotational mechanical motion of quantum system by taking advantages in ultra strong dispersion medium provided by quantum coherence in lambda system. The enhanced Fizeau effect on a single atom is observed. digital.library.unt.edu/ark:/67531/metadc849750/
Analysis and Optimization of Graphene FET based Nanoelectronic Integrated Circuits
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Like cell to the human body, transistors are the basic building blocks of any electronics circuits. Silicon has been the industries obvious choice for making transistors. Transistors with large size occupy large chip area, consume lots of power and the number of functionalities will be limited due to area constraints. Thus to make the devices smaller, smarter and faster, the transistors are aggressively scaled down in each generation. Moore's law states that the transistors count in any electronic circuits doubles every 18 months. Following this Moore's law, the transistor has already been scaled down to 14 nm. However there are limitations to how much further these transistors can be scaled down. Particularly below 10 nm, these silicon based transistors hit the fundamental limits like loss of gate control, high leakage and various other short channel effects. Thus it is not possible to favor the silicon transistors for future electronics applications. As a result, the research has shifted to new device concepts and device materials alternative to silicon. Carbon is the next abundant element found in the Earth and one of such carbon based nanomaterial is graphene. Graphene when extracted from Graphite, the same material used as the lid in pencil, have a tremendous potential to take future electronics devices to new heights in terms of size, cost and efficiency. Thus after its first experimental discovery of graphene in 2004, graphene has been the leading research area for both academics as well as industries. This dissertation is focused on the analysis and optimization of graphene based circuits for future electronics. The first part of this dissertation considers graphene based transistors for analog/radio frequency (RF) circuits. In this section, a dual gate Graphene Field Effect Transistor (GFET) is considered to build the case study circuits like voltage controlled oscillator (VCO) and low noise amplifier (LNA). The behavioral model of the transistor is modeled in different tools: well accepted EDA (electronic design automation) and a non-EDA based tool i.e. \simscape. This section of the dissertation addresses the application of non-EDA based concepts for the analysis of new device concepts, taking LC-VCO and LNA as a case study circuits. The non-EDA based approach is very handy for a new device material when the concept is not matured and the model files are not readily available from the fab. The results matches very well with that of the EDA tools. The second part of the section considers application of multiswarm optimization (MSO) in an EDA tool to explore the design space for the design of LC-VCO. The VCO provides an oscillation frequency at 2.85 GHz, with phase noise of less than -80 dBc/Hz and power dissipation less than 16 mW. The second part of this dissertation considers graphene nanotube field effect transistors (GNRFET) for the application of digital domain. As a case study, static random access memory (SRAM) hs been design and the results shows a very promising future for GNRFET based SRAM as compared to silicon based transistor SRAM. The power comparison between the two shows that GNRFET based SRAM are 93% more power efficient than the silicon transistor based SRAM at 45 nm. In summary, the dissertation is to expected to aid the state of the art in following ways: 1) A non-EDA based tool has been used to characterize the device and measure the circuit performance. The results well matches to that obtained from the EDA tools. This tool becomes very handy for new device concepts when the simulation needs to be fast and accuracy can be tradeoff with. 2)Since an analog domain lacks well-design design paradigm, as compared to digital domain, this dissertation considers case study circuits to design the circuits and apply optimization. 3) Performance comparison of GNRFET based SRAM to the conventional silicon based SRAM shows that with maturation of the fabrication technology, graphene can be very useful for digital circuits as well. digital.library.unt.edu/ark:/67531/metadc849755/
Electrodeposited Metal Matrix Composites for Enhanced Corrosion Protection and Mechanical Properties
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In the oil and gas industry, high corrosion resistance and hardness are needed to extend the lifetime of the coatings due to exposure to high stress and salt environments. Electrodeposition has become a favorable technique in synthesizing coatings because of low cost, convenience, and the ability to work at low temperatures. Electrodeposition of metal matrix composites has become popular for enhanced corrosion resistance and hardness in the oil and gas industry because of the major problems that persist with corrosion. Two major alloys of copper-nickel, 90-10 and 70-30, were evaluated for microbial corrosion protection in marine environments on a stainless steel substrate. Copper and copper alloys are commonly used in marine environments to resist biofouling of materials by inhibiting microbial growth. Literature surveying the electrodeposition of Cu-Ni incorporated with nano- to micro- particles to produce metal matrix composites has been reviewed. Also, a novel flow cell design for the enhanced deposition of metal matrix composites was examined to obtain the optimal oriented structure of the layered silicates in the metal matrix. With the addition of montmorillonite into the Ni and Cu-Ni matrix, an increase in strength, adhesion, wear and fracture toughness of the coating occurs, which leads to an increase corrosion resistance and longevity of the coating. These coatings were evaluated for composition and corrosion using many different types of instrumental and electrochemical techniques. The overall corrosion resistance and mechanical properties were improved with the composite films in comparison to the pure metals, which proves to be advantageous for many economic sectors including the oil and gas industry. digital.library.unt.edu/ark:/67531/metadc849736/
"For the Ruined Body"
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This dissertation contains two parts: Part I, "Self-Elegy as Self-Creation Myth," which discusses the self-elegy, a subgenre of the contemporary American elegy; and Part II, For the Ruined Body, a collection of poems. Traditionally elegies are responses to death, but modern and contemporary self-elegies question the kinds of death, responding to metaphorical not literal deaths. One category of elegy is the self-elegy, which turns inward, focusing on loss rather than death, mourning aspects of the self that are left behind, forgotten, or aspects that never existed. Both prospective and retrospective, self-elegies allow the self to be reinvented in the face of loss; they mourn past versions of selves as transient representations of moments in time. Self-elegies pursue the knowledge that the selves we create are fleeting and flawed, like our bodies. However by acknowledging painful self-truths, speakers in self-elegies exert agency; they participate in their own creation myths, actively interpreting and incorporating experiences into their identity by performing dreamlike scenarios and sustaining an intimate, but self-critical, voice in order to: one, imagine an alternate self to create distance and investigate the evolution of self-identity, employing hindsight and self-criticism to offer advice; two, reinterpret the past and its role in creating and shaping identity, employing a tone of resignation towards the changing nature of the self. This self-awareness, not to be confused with self-acceptance, is often the only consolation found. digital.library.unt.edu/ark:/67531/metadc849739/
Social Anxiety and Non-Medical Prescription Stimulant Use among College Students
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Current evidence suggests that non-medical prescription stimulant (NMPS) use is on the rise, particularly among college students. Identifying individuals at risk for regular and problematic use is a critical step towards the development of effective intervention efforts. A growing body of work has noted that individuals with elevated levels of social anxiety (SA) or social anxiety disorder are at an enhanced risk for developing substance use problems, including NMPS use disorder. Despite the relevance of SA and NMPS use among college students, no studies have attempted to examine subclinical SA or the relation between SA and NMPS use among college students specifically. Thus, the present study sought to extend this area by testing the relation of SA symptoms and NMPS use frequency among college students. A large online study of college students was conducted (N=1604) to identify 252 NMPS users (18-25 years; 68.3% female). A hierarchical linear regression was used to test the moderation of positive prescription stimulant expectancies on SA symptoms in predicting past year NMPS use frequency. A subsample of 15 participants was also brought into the lab to assess subjective (State Anxiety) and physiological (salivary cortisol) responding to a social stressor task. Overall, the current study did not provide evidence that SA, via retrospective self-report or real-time responding was related to past year NMPS use frequency. Additional research is needed to resolve the discrepancies between the present findings and prior work. digital.library.unt.edu/ark:/67531/metadc849701/
Virtual Entrepreneurship: Explicating the Antecedents of Firm Performance
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Prior research has examined entrepreneurial businesses spatially located in the physical or offline context; however, recent radical information and technological breakthroughs allow entrepreneurs to launch their businesses completely online. The growth of the online business industry has been phenomenal. Predictions for worldwide online sales estimate it to reach $2 trillion in 2016. Virtual entrepreneurship refers to the pursuit and exploitation of opportunities via virtual platforms. Web 2.0 cybermediaries offer web-based platforms that function similarly to traditional intermediaries in a virtual setting and minimize barriers to entry for virtual entrepreneurial firms. The use of such cybermediaries with increasing success suggests an implicit shift in the dominant logic that typically underpins the functioning of entrepreneurial firms operating in the physical world. In this relatively uncharted territory, marked by a focus on profit, cooperation, collaboration and community, three ideal-type institutional logics i.e. Market, Corporation and Community, blend together. It is posited that a Virtual Entrepreneurial Logic guides the norms, behaviors, and practices of entrepreneurial firms operating via these virtual platforms. This raises the question whether the blending of three ideal-type logics leads to the existence of different antecedents of performance. A business model antecedent addressing the economic dimension, a community antecedent addressing the community dimension and a co-creation antecedent addressing the collaborative dimension of the Virtual Entrepreneurial Logic were therefore empirically examined in this study. Thus, three research questions were investigated to explicate the antecedents. Primary data from 1396 virtual entrepreneurial firms was collected (business model antecedent n=366, community antecedent n=732 and co-creation antecedent n= 298) to test the proposed hypotheses. Results provided support for the three antecedents. This study makes important theoretical and practical contributions to understanding the domain of virtual entrepreneurship from a blended logics perspective. Using the theoretical lens provided by institutional logics helps shed light on the pivotal role played by cybermediary platforms in the Web 2.0 context. The primary role of synergistic effects, cooperative behavior, and collaboration have important implications for virtual entrepreneurship. Findings also contribute to other related streams in entrepreneurship such as microenterprises. The study offers theoretical extensions of prior work on co-creation to virtual small entrepreneurial ventures. From a practical standpoint, insights can help entrepreneurs to better understand and leverage performance drivers in virtual contexts in general and on cybermediary platforms in particular. digital.library.unt.edu/ark:/67531/metadc849704/
Unpacking Self in Clutter and Cloth: Curator as Artist/Researcher/Teacher
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This a/r/tographic dissertation offers opportunities to interrogate curator identity and curator ways of being in both public and private spaces. Instead of an authoritative or prescriptive look at the curatorial, this dissertation as catalogue allows for uncertainty, for messiness, for vulnerable spaces where readers are invited into an exhibition of disorderly living. Stitched throughout the study are stories of mothering and the difficulties that accompanied the extremely early birth of my daughter. Becoming a mother provoked my curating in unexpected ways and allowed me to reconsider the reasons I collect, display, and perform as a curator. It was through the actual curating of familial material artifacts in the exhibition Dress Stories, I was able to map the journey of my curatorial turns. My engagement with clothing in the inquiry was informed by the work of Sandra Weber and Claudia Mitchell, where dress as a methodology allows for spaces to consider autobiography, identity, and practice. It was not until the exhibition was over, I was able to discover new ways to thread caring, collecting, and cataloging ourselves as curators, artists, researchers, teachers, and mothers. It prompts curators and teachers to consider possibilities for failure, releasing excess, and uncaring as a way to care for self, objects, and others. digital.library.unt.edu/ark:/67531/metadc849713/
Biomass-Derived Activated Carbon through Self-Activation Process
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Self-activation is a process that takes advantage of the gases emitted from the pyrolysis process of biomass to activate the converted carbon. The pyrolytic gases from the biomass contain CO2 and H2O, which can be used as activating agents. As two common methods, both of physical activation using CO2 and chemical activation using ZnCl2 introduce additional gas (CO2) or chemical (ZnCl2), in which the CO2 emission from the activation process or the zinc compound removal by acid from the follow-up process will cause environmental concerns. In comparison with these conventional activation processes, the self-activation process could avoid the cost of activating agents and is more environmentally friendly, since the exhaust gases (CO and H2) can be used as fuel or feedstock for the further synthesis in methanol production. In this research, many types of biomass were successfully converted into activated carbon through the self-activation process. An activation model was developed to describe the changes of specific surface area and pore volume during the activation. The relationships between the activating temperature, dwelling time, yield, specific surface area, and specific pore volume were detailed investigated. The highest specific surface area and pore volume of the biomass-derived activated carbon through the self-activation process were up to 2738 m2 g-1 and 2.209 cm3 g-1, respectively. Moreover, the applications of the activated carbons from the self-activation process have been studied, including lithium-ion battery (LIB) manufacturing, water cleaning, oil absorption, and electromagnetic interference (EMI) shielding. digital.library.unt.edu/ark:/67531/metadc849716/
Hungering for Independence: The Relationship between Food and Morale in the Continental Army, 1775-1783
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An adequate supply of the right kinds of foods is critical to an army's success on the march and on the battlefield. Good food supplies and a dire lack of provisions have profound effects on the regulation, confidence, esprit de corps, and physical state of an army. The American War of Independence (1775-1783) provides a challenging case study of this principle. The relationship between food and troop morale has been previously discussed as just one of many factors that contributed to the success of the Continental Army, but has not been fully explored as a single issue in its own right. I argue that despite the failures of three provisioning system adopted by the Continental Congress - the Commissariat, the state system of specific supplies, and the contract system - the army did keep up its morale and achieve the victory that resulted in independence from Great Britain. The evidence reveals that despite the poor provisioning, the American army was fed in the field for eight years thanks largely to its ability to forage for its food. This foraging system, if it can be called a system, was adequate to sustain morale and perseverance. digital.library.unt.edu/ark:/67531/metadc849718/
Fatigue Behavior of A356 Aluminum Alloy
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Metal fatigue is a recurring problem for metallurgists and materials engineers, especially in structural applications. It has been responsible for many disastrous accidents and tragedies in history. Understanding the micro-mechanisms during cyclic deformation and combating fatigue failure has remained a grand challenge. Environmental effects, like temperature or a corrosive medium, further worsen and complicate the problem. Ultimate design against fatigue must come from a materials perspective with a fundamental understanding of the interaction of microstructural features with dislocations, under the influence of stress, temperature, and other factors. This research endeavors to contribute to the current understanding of the fatigue failure mechanisms. Cast aluminum alloys are susceptible to fatigue failure due to the presence of defects in the microstructure like casting porosities, non-metallic inclusions, non-uniform distribution of secondary phases, etc. Friction stir processing (FSP), an emerging solid state processing technique, is an effective tool to refine and homogenize the cast microstructure of an alloy. In this work, the effect of FSP on the microstructure of an A356 cast aluminum alloy, and the resulting effect on its tensile and fatigue behavior have been studied. The main focus is on crack initiation and propagation mechanisms, and how stage I and stage II cracks interact with the different microstructural features. Three unique microstructural conditions have been tested for fatigue performance at room temperature, 150 °C and 200 °C. Detailed fractography has been performed using optical microscopy, scanning electron microscopy (SEM) and electron back scattered diffraction (EBSD). These tools have also been utilized to characterize microstructural aspects like grain size, eutectic silicon particle size and distribution. Cyclic deformation at low temperatures is very sensitive to the microstructural distribution in this alloy. The findings from the room temperature fatigue tests highlight the important role played by persistent slip bands (PSBs) in fatigue crack initiation. At room temperature, cracks initiate along PSBs in the absence of other defects/stress risers, and grow transgranularly. Their propagation is retarded when they encounter grain boundaries. Another major finding is the complete transition of the mode of fatigue cracking from transgranular to intergranular, at 200 °C. This occurs when PSBs form in adjacent grains and impinge on grain boundaries, raising the stress concentration at these locations. This initiates cracks along the grain boundaries. At these temperatures, cyclic deformation is no longer microstructure- dependent. Grain boundaries don’t impede the progress of cracks, instead aid in their propagation. This work has extended the current understanding of fatigue cracking mechanisms in A356 Al alloys to elevated temperatures. digital.library.unt.edu/ark:/67531/metadc849720/
Design of New Monodentate Ligands for Regioselectivity and Enantioselectivity Tuning in Late Transition Metal Catalysis
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The ability of gold(I) to activate many types of unsaturated bonds toward nucleophilic attack was not widely recognized until the early 2000s. One major challenge in gold catalysis is the control over regioselectivity when there are two or more possible products as a result of complicated mechanistic pathways. It is well know that the choice of ligand can have dramatic effects on which pathway is being followed but very rarely are the reasons for this selectivity understood. The synthesis of new acyclic diaminocarbenes was developed and a study of the ligand effects on the regioselectivity of a gold-catalyzed domino enyne cyclization hydroarylation reaction and a Nazarov cyclization was undertaken. New chiral acyclic diaminocarbenes were also developed and tested along side new C3-symmetric phosphite ligands in an asymmetric intramolecular hydroamination of allenes. Structure activity correlations were developed for the potential use in further rational ligand design. The synthesis of 6a,7-dihydro-5-amino-dibenzo[c,g]chromene derivatives via a gold-catalyzed domino reaction of alkynylbenzaldehydes in the presence of secondary amines was developed. These were sent to be screened for biological activity. digital.library.unt.edu/ark:/67531/metadc849723/
Stable Nanocrystalline Au Film Structures for Sliding Electrical Contacts
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Hard gold thin films and coatings are widely used in electronics as an effective material to reduce the friction and wear of relatively less expensive electrically conductive materials while simultaneously seeking to provide oxidation resistance and stable sliding electrical contact resistance (ECR). The main focus of this dissertation was to synthesize nanocrystalline Au films with grain structures capable of remaining stable during thermal exposure and under sliding electrical contact stress and the passing of electrical current. Here we have utilized a physical vapor deposition (PVD) technique, electron beam evaporation, to synthesize Au films modified by ion implantation and codeposited ZnO hardened Au nanocomposites. Simultaneous friction and ECR experiments of low fluence (< 1x10^17 cm^-2) He and Ar ion implanted Au films showed reduction in friction coefficients from ~1.5 to ~0.5 and specific wear rates from ~4x10^-3 to ~6x10^-5 mm^3/N·m versus as-deposited Au films without significant change in sliding ECR (~16 mΩ). Subsurface microstructural changes of He implanted films due to tribological stress were analyzed via site-specific cross-sectional transmission electron microscopy (TEM) and revealed the formation of nanocrystalline grains for low energy (22.5 keV) implantation conditions as well as the growth and redistribution of cavities. Nanoindentation hardness results revealed an increase from 0.84 GPa for as-deposited Au to ~1.77 GPa for Au uniformly implanted with 1 at% He. These strength increases are correlated with an Orowan hardening mechanism that increases proportionally to (He concentration)1/3. Au-ZnO nanocomposite films in the oxide dilute regime (< 5 vol% ZnO) were investigated for low temperature aging stability in friction and ECR. Annealing at 250 °C for 24 hours Au-(2 vol%)ZnO retained a friction coefficient comparable to commercial Ni hardened Au of ~ 0.3 and sliding ECR values of ~35 mΩ. Nanoindentation hardness increases of these films (~2.6 GPa for 5 vol% ZnO) are correlated to microstructure via high resolution TEM and scanning electron microscope cross-sections to both Hall-Petch and Orowan strengthening mechanisms. Also presented is a correlation between electrical resistivity and grain size in the oxide dilute range based on the Mayadas-Shatzkes (M-S) electron scattering model. Using the M-S model in combination with a model describing solute drag stabilized grain growth kinetics we present a new technique to probe grain boundary mobility and thermal stability from in-situ electrical resistivity measurements during annealing experiments. digital.library.unt.edu/ark:/67531/metadc849672/
Highly Stretchable Miniature Strain Sensor for Large Dynamic Strain Measurement
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This thesis aims to develop a new type of highly stretchable strain sensor to measure large deformation of a specimen subjected to dynamic loading. The sensor was based on the piezo-resistive response of carbon nanotube(CNT)/polydimethysiloxane (PDMS) composites thin films, some nickel particles were added into the sensor composite to improve the sensor performance. The piezo-resistive response of CNT composite gives high frequency response in strain measurement, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measuring large strain (up to 26%) with an excellent linearity and a fast frequency response under quasi-static test, the delay time for high strain rate test is just 30 μs. This stretchable strain sensor is also able to exhibit much higher sensitivities, with a gauge factor of as high as 80, than conventional foil strain gauges. digital.library.unt.edu/ark:/67531/metadc849674/
Decision Makers’ Cognitive Biases in Operations Management: An Experimental Study
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Behavioral operations management (BOM) has gained popularity in the last two decades. The main theme in this new stream of research is to include the human behavior in Operations Management (OM) models to increase the effectiveness of such models. BOM is classified into 4 areas: cognitive psychology, social psychology, group dynamics and system dynamics (Bendoly et al. 2010). This dissertation will focus on the first class, namely cognitive psychology. Cognitive psychology is further classified into heuristics and biases. Tversky and Kahneman (1974) discussed 3 heuristics and 13 cognitive biases that usually face decision makers. This dissertation is going to study 6 cognitive biases under the representativeness heuristic. The model in this dissertation states that cognitive reflection of the individual (Frederick 2005) and training about cognitive biases in the form of warning (Kaufmann and Michel 2009) will help decisions’ makers make less biased decisions. The 6 cognitive biases investigated in this dissertation are insensitivity to prior probability, insensitivity to sample size, misconception of chance, insensitivity to predictability, the illusion of validity and misconception of regression. 6 scenarios in OM contexts have been used in this study. Each scenario corresponds to one cognitive bias. Experimental design has been used as the research tool. To see the impact of training, one group of the participants received the scenarios without training and the other group received them with training. The training consists of a brief description of the cognitive bias as well as an example of the cognitive bias. Cognitive reflection is operationalized using cognitive reflection test (CRT). The survey was distributed to students at University of North Texas (UNT). Logistic regression has been employed to analyze data. The research shows that participants show the cognitive biases proposed by Tversky and Kahneman. Moreover, CRT is significant factor to predict the cognitive bias in two scenarios. Finally, providing training in terms of warning helps participants to make more rational decisions in 4 scenarios. This means that although cognitive biases are inherent in the mind of people, management of corporations has the tool to educate its managers and professionals about such biases which helps companies make more rational decisions. digital.library.unt.edu/ark:/67531/metadc849675/
Community-based Logistics and Supply Chain Management: Developing, Testing and Validating Conceptual Models
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The field of Logistics and Supply Chain Management (LSCM) suggests that transactions, collaboration, and value are important in the supply and delivery of products and services to meet the need of impoverished end-consumers. In many cases, the application of LSCM is paramount in most strategic decision-making efforts. Therefore, this research explores the applications of LSCM processes and activities within the community-based context. The methodology used to address the research questions consisted of a hybrid of mixed methods. This mixed methodology provides three essays that investigate the application and development of LSCM in the community-based context. The essays address the flow of charitable products and services through supply chains. The dissertation does not pay close attention to the first-tier suppliers’ suppliers, which is looking at the originating flow of goods and services (raw materials, manufacturing, etc.). However, the dissertation puts a focus on products and services supplied to focal organizations and how these products are then passed on to end-consumers. Essay I looks at the transaction (costs) that ensue from the supply of charitable products. Essay II analyzes a social service ecosystem and investigates how the network of organizations enable the distribution of charitable products and services. Lastly, Essay III examines the delivery of valuable services to the end-consumers, and what tools Community-Based Enterprises (CBEs) should focus on to develop and retain end-consumers in impoverished communities. The research provides conceptual models that review some fundamental LSCM achievement gaps in supplying, delivering and providing social services to end users within impoverished communities. The dissertation draws upon literature from the fields of economics, marketing, social science, and logistics and supply chain management. The dissertation uses the primary research method of unstructured and semi-structured interviews, case studies, written survey instruments and system dynamics within three studies. The studies resolve to look into the term Community-Based Logistics and Supply Chain Management (CBLSCM) as employed by social service providers in the logistics and supply chain context and investigate how it applies to impoverished communities. The research identifies conceptual models that can be used to explain the role of LSCM within humanitarian aid context. The models offer insights on the managerial implications and evidence of using LSCM processes and techniques within impoverished communities. The research has considered that the type of transactional relationships, structure, shared value, service systems, and consumer value, retention and management mechanisms can be achieved utilizing LSCM. digital.library.unt.edu/ark:/67531/metadc849676/
Evaluating the Pulse Sensor as a Low-Cost and Portable Measurement of Blood Pulse Waveform
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This study was aimed at determining whether the digital volume pulse waveform using the Pulse Sensor can be used to extract features related to arterial compliance. The Pulse Sensor, a low-cost photoplethysmograph, measures green light reflection in the finger and generates output, which is indicative of blood flow and can be read by the low-cost Arduino UNO™. The Pulse Sensor code was modified to increase the sampling frequency and to capture the data in a file, which is subsequently used for waveform analysis using programs written in the R system. Waveforms were obtained using the Pulse Sensor during two 30-s periods of seated rest, in each of 44 participants, who were between the ages of 20 and 80 years. For each cardiac cycle, the first four derivatives of the waveform were calculated and low-pass filtered by convolution before every differentiation step. The program was written to extract 19 features from the pulse waveform and its derivatives. These features were selected from those that have been reported to relate to the physiopathology of hemodynamics. Results indicate that subtle features of the pulse waveform can be calculated from the fourth derivative. Feature misidentification occurred in cases of saturation or low voltage and resulted in outliers; therefore, trimmed means of the features were calculated by automatically discarding the outliers. There was a high efficiency of extraction for most features. Significant relationships were found between several of the features and age, and systolic, diastolic, and mean arterial blood pressure, suggesting that these features might be employed to predict arterial compliance. Further improvements in experimental design could lead to a more detailed evaluation of the Pulse Sensor with respect to its capability to predict factors related to arterial compliance. digital.library.unt.edu/ark:/67531/metadc849682/
The Effectiveness of a Professional Learning Community on Student Achievement in Elementary Reading and Mathematics in a Large Urban School District
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The study was to determine the impact of a Professional Learning Community on student achievement as measured by the state's criterion referenced reading and mathematics achievement tests. Data for this study were extracted from the school district's student database. Two cohorts of 90 students each were randomly selected from a population of approximately 600 students in 3 schools that participated in a Professional Learning Community (treatment) and 3 schools that did not (control). Professional Learning Communities known as PLCs, can serve as a major theoretical framework to promote the improvement of classroom teachers' instructional practice, teacher effectiveness and student achievement. Reading and mathemtics mean scale scores were extracted at three time points (year 1, year 2, and year 3) across three grades (grade 3, grade 4 and grade 5). Test for equality of variance found that no statistically significant difference existed between the mean scale scores of the two cohorts at the beginning of the study. The findings revealed that both cohorts trend toward increased academic achievement from year to year individually; however, when compared to each other, no statistically significant difference existed. Further research is indicated to examine each PLC for implementation, support and leadership as they relate to the PLC and a focus on instruction and learning. digital.library.unt.edu/ark:/67531/metadc849683/
"Goodness and Mercy": Stories
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The stories in this collection represent an increasingly transcultural world by exploring the intersection of cultures and identities in border spaces, particularly the Mexican-American border. Characters, regardless of ethnicity, experience the effects of migration and deportation in schools, hometowns, relationships, and elsewhere. The collection as a whole focuses on the issues and themes found in Mexican-American literature, such as loss, separation, and the search for identity. digital.library.unt.edu/ark:/67531/metadc849684/
Reactions and Interfacial Behaviors of the Water–Amorphous Silica System from Classical and Ab Initio Molecular Dynamics Simulations
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Due to the wide application of silica based systems ranging from microelectronics to nuclear waste disposal, detailed knowledge of water-silica interactions plays an important role in understanding fundamental processes, such as glass corrosion and the long term reliability of devices. In this dissertation, atomistic computer simulation methods have been used to explore and identify the mechanisms of water-silica reactions and the detailed processes that control the properties of the water-silica interfaces due to their ability to provide atomic level details of the structure and reaction pathways. The main challenges of the amorphous nature of the silica based systems and nano-porosity of the structures were overcome by a combination of simulation methodologies based on classical molecular dynamics (MD) simulations with Reactive Force Field (ReaxFF) and density functional theory (DFT) based ab initio MD simulations. Through the development of nanoporous amorphous silica structure models, the interactions between water and the complex unhydroxylated internal surfaces identified the unusual stability of strained siloxane bonds in high energy ring structure defects, as well as the hydroxylation reaction kinetics, which suggests the difficulty in using DFT methods to simulate Si-O bond breakage with reasonable efficiency. Another important problem addressed is the development of silica gel structures and their interfaces, which is considered to control the long term residual dissolution rate in borosilicate glasses. Through application of the ReaxFF classical MD potential, silica gel structures which mimic the development of interfacial layers during silica dissolution were created A structural model, consisting of dense silica, silica gel, and bulk water, and the related interfaces was generated, to represent the dissolution gel structure. High temperature evolution of the silica-gel-water (SGW) structure was performed through classical MD simulation of the system, and growth of the gel into the water region occurred, as well as the formation of intermediate range structural features of dense silica. Additionally, hydroxylated silica monomers (SiO4H4) and longer polymerized silica chains were formed in the water region, indicating that glass dissolution is occurring, even at short time frames. The creation of the SGW model provides a framework for a method of identifying how interfacial structures which develop at glass-water interfaces can be incorporated into atomistic models for additional analysis of the dissolution of silicates in water. digital.library.unt.edu/ark:/67531/metadc849660/
Lipidomic Analysis of Single Cells and Organelles Using Nanomanipulation Coupled to Mass Spectrometry
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The capability to characterize disease states by way of determining novel biomarkers has led to a high demand of single cell and organelle analytical methodologies due to the unexpected heterogeneity present in cells of the same type. Lipids are of particular interest in the search for biomarkers due to their active roles in cellular metabolism and energy storage. Analyzing localized lipid chemistry from individual cells and organelles is challenging however, due to low analyte volume, limited discriminate instrumentation, and common requirements of separation procedures and expenditure of cell sample. Using nanomanipulation in combination with mass spectrometry, individual cells and organelles can be extracted from tissues and cultures in vitro to determine if heterogeneity at the cellular level is present. The discriminate extraction of a single cell or organelle allows the remainder of cell culture or tissue to remain intact, while the high sensitivity and chemical specificity of mass spectrometry provides structural information for limited volumes without the need for chromatographic separation. Mass analysis of lipids extracted from individual cells can be carried out in multiple mass spectrometry platforms through direct-inject mass spectrometry using nanoelectrospray-ionization and through matrix-assisted laser/desorption ionization. digital.library.unt.edu/ark:/67531/metadc849662/
'My Tattooed Mind'
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This thesis features a collection of nonfiction essays. digital.library.unt.edu/ark:/67531/metadc849670/
Exploring Inorganic Catalysis with Electronic Structure Simulations
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Organometallic catalysis has attracted significant interest from both industry and academia due to its wide applications in organic synthetic transformations. Example of such transformations include the reaction of a zinc carbenoid with olefins to form cyclopropanes. The first project is a computational study using both density functional and correlated wavefunction methods of the reaction between ethylene and model zinc carbenoid, nitrenoid and oxenoid complexes (L-Zn-E-X, E = CH2, NH or O, L = X = I or Cl). It was shown that cyclopropanation of ethylene with IZnCH2I and aziridination of ethylene with IZnNHI proceed via a single-step mechanism with an asynchronous transition state. The reaction barrier for the aziridination with IZnNHI is lower than that of cyclopropanation. Changing the leaving group of IZnNHI from I to Cl, changes the mechanism of the aziridination reaction to a two-step pathway. The calculation results from the epoxidation with IZnOI and ClZnOCl oxenoids suggest a two-step mechanism for both oxenoids. Another important example of organometallic catalysis is the formation of alkyl arenes from arenes and olefins using transition metal catalysis (olefin hydroarylation). We studied with DFT methods the mechanism of a novel Rh catalyst (FlDAB)Rh(TFA)(η2–C2H4) [FlDAB = N,N’ -bis(pentafluorophenyl)-2,3-dimethyl-1,4-diaza-1,3-butadiene; TFA = trifluoroacetate] that converts benzene, ethylene and air-recyclable Cu(II) oxidants to styrene. Possible mechanisms are discussed. digital.library.unt.edu/ark:/67531/metadc849685/
Interfacial Electrochemistry of Cu/Al Alloys for IC Packaging and Chemical Bonding Characterization of Boron Doped Hydrogenated Amorphous Silicon Films for Infrared Cameras
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We focused on a non-cooling room temperature microbolometer infrared imaging array device which includes a sensing layer of p-type a-Si:H component layers doped with boron. Boron incorporation and bonding configuration were investigated for a-Si:H films grown by plasma enhanced chemical deposition (PECVD) at varying substrate temperatures, hydrogen dilution of the silane precursor, and dopant to silane ratio using multiple internal reflection infrared spectroscopy (MIR-IR). This study was then confirmed from collaborators via Raman spectroscopy. MIR-IR analyses reveal an interesting counter-balance relationship between boron-doping and hydrogen-dilution growth parameters in PECVD-grown a-Si:H. Specifically, an increase in the hydrogen dilution ratio (H2/SiH4) or substrate temperature was found to increase organization of the silicon lattice in the amorphous films. It resulted in the decrease of the most stable SiH bonding configuration and thus decrease the organization of the film. The new chemical bonding information of a-Si:H thin film was correlated with the various boron doping mechanisms proposed by theoretical calculations. The study revealed the corrosion morphology progression on aluminum alloy (Al, 0.5% Cu) under acidic chloride solution. This is due to defects and a higher copper content at the grain boundary. Direct galvanic current measurement, linear sweep voltammetry (LSV), and Tafel plots are used to measure corrosion current and potential. Hydrogen gas evolution was also observed (for the first time) in Cu/Al bimetallic interface in areas of active corrosion. Mechanistic insight that leads to effective prevention of aluminum bond pad corrosion is explored and discussed. (Chapter 4) Aluminum bond pad corrosion activity and mechanistic insight at a Cu/Al bimetallic interface typically used in microelectronic packages for automotive applications were investigated by means of optical and scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and electrochemistry. Screening of corrosion variables (temperature, moisture, chloride ion concentration, pH) have been investigated to find their effect on corrosion rate and to better understand the Al/Cu bimetallic corrosion mechanism. The study revealed the corrosion morphology progression on aluminum alloy (Al, 0.5% Cu) under acidic chloride solution. The corrosion starts as surface roughening which evolves into a dendrite structure and later continues to grow into a mud-crack type corrosion. SEM showed the early stage of corrosion with dendritic formation usually occurs at the grain boundary. This is due to defects and a higher copper content at the grain boundary. The impact of copper bimetallic contact on aluminum corrosion was explored by sputtering copper microdots on aluminum substrate. Copper micropattern screening revealed that the corrosion is activated on the Al/Cu interface area and driven by the large potential difference; it was also seen to proceed at much higher rates than those observed with bare aluminum. Direct galvanic current measurement, linear sweep voltammetry (LSV), and Tafel plots are used to measure corrosion current and potential. Hydrogen gas evolution was also observed (for the first time) in Cu/Al bimetallic interface in areas of active corrosion. Mechanistic insight that leads to effective prevention of aluminum bond pad corrosion is explored and discussed. Micropattern corrosion screening identified hydrogen evolution and bimetallic interface as the root cause of Al pad corrosion that leads to Cu ball lift-off, a fatal defect, in Cu wire bonded device. Complete corrosion inhibition can be achieved by strategically disabling the mutually coupled cathodic and anodic reaction cycles. digital.library.unt.edu/ark:/67531/metadc849696/
Let the Dogs Bark: The Psychological War in Vietnam, 1960-1968
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Between 1960 and 1968 the United States conducted intensive psychological operations (PSYOP) in Vietnam. To date, no comprehensive study of the psychological war there has been conducted. This dissertation fills that void, describing the development of American PSYOP forces and their employment in Vietnam. By looking at the complex interplay of American, North Vietnamese, National Liberation Front (NLF) and South Vietnamese propaganda programs, a deeper understanding of these activities and the larger war emerges. The time period covered is important because it comprises the initial introduction of American PSYOP advisory forces and the transition to active participation in the war. It also allows enough time to determine the long-term effects of both the North Vietnamese/NLF and American/South Vietnamese programs. Ending with the 1968 Tet Offensive is fitting because it marks both a major change in the war and the establishment of the 4th Psychological Operations Group to manage the American PSYOP effort. This dissertation challenges the argument that the Northern/Viet Cong program was much more effective that the opposing one. Contrary to common perceptions, the North Vietnamese propaganda increasingly fell on deaf ears in the south by 1968. This study also provides support for understanding the Tet Offensive as a desperate gamble born out of knowledge the tide of war favored the Allies by mid-1967. The trend was solidly towards the government and the NLF increasingly depended on violence to maintain control. The American PSYOP forces went to Vietnam with little knowledge of the history and culture of Vietnam or experience conducting psychological operations in a counterinsurgency. As this dissertation demonstrates, despite these drawbacks, they had considerable success in the period covered. Although facing an experienced enemy in the psychological war, the U.S. forces made great strides in advising, innovating techniques, and developing equipment. I rely extensively on untapped sources such as the Foreign Broadcast Information Service transcripts, Captured Document Exploitation Center files, and access to the U.S. Army Special Operations Command Archives. Additionally, I have digitized databases such as the Hamlet Evaluation System and Terrorist Incident Reporting System for Geographic Information System software analysis. The maps provide examples of the possibilities available to the historian using these datasets. digital.library.unt.edu/ark:/67531/metadc849646/
Bioinspired and biocompatible coatings of poly(butylene adipate-co-terephthalate) and layer double hydroxide composites for corrosion resistance
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Hierarchical arrangement of biological composites such as nacre and bone containing high filler (ceramic) content results in high strength and toughness of the natural material. In this study we mimic the design of layered bone microstructure and fabricate an optimal multifunctional bio-nanocomposite having strength, toughness and corrosion resistance. Poly (butylene adipate-co-terephthalate) (PBAT), a biodegradable polymer was used as a substrate material with the reinforcement of LDH (Layered double hydroxide) as a nanofiller in different concentrations to achieve enhancement in mechanical properties as well as processing related thermostability. Corrosion resistance was increased by mimicking a layered structured which incorporated a tortuous diffusion path. digital.library.unt.edu/ark:/67531/metadc849647/
Developing Policy for a Tech Program Based on Understanding Organizational Practices
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This thesis contributes to research that informs the studies of organizational management and organizational anthropology. It examines the internal hierarchy and organizational practices of a Tech Company and describes how findings contributed to policy recommendations aimed towards supporting a “guild” model for organizational success. The data collecting and research were undertaken while working as an employee of the Tech Program and subsequent analysis continued past the end of that phase of work. Methods included semi-structured interviews which captured the sentiments and understandings of employees within the organization, and a questionnaire which revealed sentiments and experiences from former employees. These were buttressed with participant observation engaged through a participatory action research methodology. Findings add to the work directed towards understanding the effect of Founder’s Syndrome within organizations. Additionally, this thesis contributes to a growing body of research centered on best practices for fostering positive organizational growth by creating lines of communication from front-line employees to management level employers. digital.library.unt.edu/ark:/67531/metadc849648/
Welcome to the Rest of It
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This creative nonfiction dissertation is a book of essays that explore the author's life and relationship to Upstate New York. The project also connects this experience to gender and trauma. Though the topics range from local history to cosmetic surgical procedures, the essays are collected by how they illuminate cultural tensions and universal truths. These essays are preceded by a critical preface that examines the differences between essays collections, books of essays, and argues for the recognition of narrative nonfiction as an artistic choice. digital.library.unt.edu/ark:/67531/metadc849651/
Learning from small data set for object recognition in mobile platforms.
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Did you stand at a door with a bunch of keys and tried to find the right one to unlock the door? Did you hold a flower and wonder the name of it? A need of object recognition could rise anytime and any where in our daily lives. With the development of mobile devices object recognition applications become possible to provide immediate assistance. However, performing complex tasks in even the most advanced mobile platforms still faces great challenges due to the limited computing resources and computing power. In this thesis, we present an object recognition system that resides and executes within a mobile device, which can efficiently extract image features and perform learning and classification. To account for the computing constraint, a novel feature extraction method that minimizes the data size and maintains data consistency is proposed. This system leverages principal component analysis method and is able to update the trained classifier when new examples become available . Our system relieves users from creating a lot of examples and makes it user friendly. The experimental results demonstrate that a learning method trained with a very small number of examples can achieve recognition accuracy above 90% in various acquisition conditions. In addition, the system is able to perform learning efficiently. digital.library.unt.edu/ark:/67531/metadc849633/
Forensic Analysis of Ink on Documents Using Direct Analyte-Probed Nanoextraction Coupled Techniques
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Analzying questioned documents in a nondestructive nature has been an issue for the forensic science community. Using nondestructive techniques such as video spectral comparator does not give reliable information due to the variations in gray or color levels that are distinguished differently by analysts. Destructive techniques such as chromatography give dependable, qualitative and quantitative, information but involves altering the evidentiary value of these questioned documents. The paradox of document examination becomes a problem when document evidence is involved, especially when trying to preserve its evidentiary value and critical data is needed. Thus, a nondestructive technique has been developed to solve the loopholes in document examinations. Direct analyte-probed nanoextraction (DAPNe) is a nanomanipulation technique that extracts ink directly off the document for further examination. A watermark is left, at most, post-extraction. DAPNe utilizes a tip emitter, pre-filled with a solvent, which is controlled in x-, y-, and z-coordinates via joystick controller and aspirates/extracts using a pressure injector. The versatility of this technique lies within the solvent chemistry and its capability to be coupled to various types of instrumentation. The extraction solvent can be altered to target specific components in the ink. For example, a chelator may be added to target metal ions found in ancient inks or methanol may be added to target certain organic resins and binding agents found in modern inks. In this study, DAPNe has been coupled to nanospray ionization mass spectrometry, fluorescence microscopy, Raman spectroscopy, matrix-assisted laser desorption ionization mass spectrometry, and laser ablation to solve questioned document concerns in the area of falsified or forged documents, redacted documents, and aging studies. digital.library.unt.edu/ark:/67531/metadc849635/
Enhancement of Light Emission from Metal Nanoparticles Embedded Graphene Oxide
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A fully oxidized state of graphene behaves as a pure insulating while a pristine graphene behaves as a pure conducting. The in-between oxide state in graphene which is the controlled state of oxide behaves as a semiconducting. This is the key condition for tuning optical band gap for the better light emitting property. The controlling method of oxide in graphene structure is known as reduction which is the mixed state of sp2 and sp3 hybrid state in graphene structure. sp2 hybridized domains correspond to pure carbon-carbon bond i.e. pristine graphene while sp3 hybridized domains correspond to the oxide bond with carbon i.e. defect in graphene structure. This is the uniqueness of the graphene-base material. Graphene is a gapless material i.e. having no bandgap energy and this property prevents it from switching device applications and also from the optoelectronic devices applications. The main challenge for this material is to tune as a semiconducting which can open the optical characteristics and emit light of desired color. There may be several possibilities for the modification of graphene-base material that can tune a band gap. One way is to find semiconducting property by doping the defects into pristine graphene structure. Other way is oxides functional groups in graphene structure behaves as defects. The physical properties of graphene depend on the amount of oxides present in graphene structure. So if there are more oxides in graphene structure then this material behaves as a insulating. By any means if it can be reduced then oxides amount to achieve specific proportion of sp2 and sp3 that can emit light of desired color. Further, after achieving light emission from graphene base material, there is more possibility for the study of non-linear optical property. In this work, plasmonic effect in graphene oxide has been focused. Mainly there are two kinds of plasmon effects have been studied, one is long range (surface) and short range (localized) plasmon. For long range plasmon gold thin film was deposited on partially reduced graphene oxide and for short range plasmon silver nanoparticles have used. Results show that there are 10-fold enhancement in light emission from partial graphene oxide coated with gold thin film while 4-fold enhancement from reduced graphene oxide solution with silver nanoparticles. Chemical method and photocatalytic method have been employed for the reduction of graphene oxide for the study of surface plasmon and localized plasmon. For the characterization UV-Vis spectrometer for absorption, spectrofluorophotometer for fluorescent emission, Raman spectrometer for material characterization, photoluminescence and time resolved photoluminescence have been utilized. Silver and gold nanoparticles are spherical of average size of 80 nm and 40 nm have been used as plasmons. digital.library.unt.edu/ark:/67531/metadc849637/
The One Electron Basis Set: Challenges in Wavefunction and Electron Density Calculations
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In the exploration of chemical systems through quantum mechanics, accurate treatment of the electron wavefunction, and the related electron density, is fundamental to extracting information concerning properties of a system. This work examines challenges in achieving accurate chemical information through manipulation of the one-electron basis set. digital.library.unt.edu/ark:/67531/metadc849642/
Evaluating a Sustainable Community Development Initiative Among the Lakota People on the Pine Ridge Indian Reservation
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This thesis details my applied thesis project and experience in the evaluation of a workforce development through sustainable constructio program. It describes the need of my client, Sweet Grass Consulting and their contractual partner, the Thunder Valley Community Development Corporation, in the evaluation of Thunder Valley CDC's Workforce Development through Sustainable Construction Program. My role involved the development of an extensive evaluation package for this program and data analysis of evaluation materials to support Thunder Valley CDC's grant-funded Workforce Development Program. I place the efforts of Thunder Valley CDC in the context of their community, the Pine Ridge Reservation of the Lakota People, and within an historical and contemporary context to highlight the implications of the efforts of Thunder Valley CDC. Using the theoretical frameworks of cultural revitalization and community economic development, I attempt to highlight two important components of Thunder Valley CDC's community development efforts - cultural revitalization for social healing, and development that emphasizes social, community and individual well-being. Thunder Valley CDC's Workforce Development through Sustainable Construction Program is still in its early stages, and so this first year of implementation very much represented a pilot phase. However, while specific successes are difficult to measure at this point, general successes are viewable in the daily operations of Thunder Valley CDC that examplify their stated mision and goals. These successes include initiatives that holistically address community needs; relevancy in the eyes of the community they serve; support for the community and for Program participants' unique challenges; and a cultural restoration and revitalization emphasis that underlies and strengthens all of this. The program thus has the potential to provide a model for community development by challenging dominant "development" paradigms and utilizing community resources and assets for community development that reflects the community's values and worldviews. digital.library.unt.edu/ark:/67531/metadc848222/
Synchrotron Radiation X-Ray Diffraction of Nickel-Titanium Shape Memory Alloy Wires during Mechanical Deformation
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Shape memory alloys (SMAs) are a new generation material which exhibits unique nonlinear deformations due to a phase transformation which allows it to return to its original shape after removal of stress or a change in temperature. It shows a shape memory effect (martensitic condition) and pseudoelasticity (austenitic condition) properties depends on various heat treatment conditions. The reason for these properties depends on phase transformation through temperature changes or applied stress. Many technological applications of austenite SMAs involve cyclical mechanical loading and unloading in order to take advantage of pseudoelasticity, but are limited due to poor fatigue life. In this thesis, I investigated two important mechanical feature to fatigue behavior in pseudoelastic NiTi SMA wires using high energy synchrotron radiation X-ray diffraction (SR-XRD). The first of these involved simple bending and the second of these involved relaxation during compression loading. Differential scanning calorimetry (DSC) was performed to identify the phase transformation temperatures. Scanning electron microscopy (SEM) images were collected for the initial condition of the NiTi SMA wires and during simple bending, SEM revealed that micro-cracks in compression regions of the wire propagate with increasing bend angle, while tensile regions tend to not exhibit crack propagation. SR-XRD patterns were analyzed to study the phase transformation and investigate micromechanical properties. By observing the various diffraction peaks such as the austenite (200) and the martensite (100), (110), and (101) planes, intensities and residual strain values exhibit strong anisotropy depending upon whether the sample is in compression or tension during simple bending. This research provides insight into two specific mechanical features in pseudoelastic NiTi SMA wires. digital.library.unt.edu/ark:/67531/metadc848138/
Competing Models of Hegemonic Masculinity in English Civil War Memoirs by Women
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This thesis examines the descriptions of Royalist and Parliamentarian masculinity in English Civil War memoirs by women through a close reading of three biographical memoirs written by Margaret Cavendish, duchess of Newcastle; Lady Ann Fanshawe; and Lucy Hutchinson. Descriptions of masculinity are evaluated through the lens of Raewyn Connell's theory of hegemonic masculinity to understand the impact two competing models of masculinity had on the social and political culture of the period. The prevailing Parliamentarian hegemonic masculinity in English Civil War memoirs is traced to its origins before the English Civil War to demonstrate how hegemonic masculinity changes over time. The thesis argues that these memoirs provide evidence of two competing models of Royalist and Parliamentarian masculinities during the Civil War that date back to changes in the Puritan meaning of the phrase “man of merit”, which influenced the development of a Parliamentarian model of masculinity. digital.library.unt.edu/ark:/67531/metadc848084/
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