UNT Theses and Dissertations - 157 Matching Results

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Accelerated Corrosion Test with Operation Simulation of All-Aluminum Microchannel Heat Exchangers

Description: 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.
Date: May 2016
Creator: Vaughan, Haydn
Partner: UNT Libraries

The Acceptance and Use of Cloud Computing Services by Small and Medium Enterprises in Lagos, Nigeria

Description: This study explored the acceptance of cloud computing (CC) services by small and medium enterprises (SMEs) in Lagos, Nigeria, which has been missing from CC services literature. It aimed to understand the motivations for adoption, the uses of the services, and the benefits they derive from it. The uses and gratification theory was applied as the theoretic framework for this endeavor. An online survey with close-ended and open-ended questions was distributed to 1200 randomly selected participants through email. In total, 392 valid responses were collected and analyzed using descriptive statistics and categories. The results found that SMEs in Lagos, Nigeria had a low level of awareness and appreciation of CC services. The adoption rate was also low. Unlike their counterparts in other regions, SMEs primary concerns were service downtime, stable power supply, and better internet access. The study found that SMEs were not taking full advantage of the capabilities of CC services. Some sections, however, were doing better than others, such as the information and communications sub-sector. This study suggested that targeted interventions should be conducted to raise the awareness of CC services in SMEs, and to improve their efficient and effective use of CC services. The uses and gratification theory was appropriate for guiding this study to understand the acceptance and use of CC services by SMEs in Lagos, Nigeria.
Date: May 2017
Creator: Azogu, Olajumoke O
Partner: UNT Libraries

Adhesion and Surface Energy Profiles of Large-area Atomic Layers of Two-dimensional MoS2 on Rigid Substrates by Facile Methods

Description: 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.
Date: May 2016
Creator: Wu, Min
Partner: UNT Libraries

Age Friendly Cities: The Bureaucratic Responsiveness Effects on Age Friendly Policy Adoption

Description: Challenging a long-held attachment to the medical model, this research develops a cultural model placing local governments at the center of policy making and refocusing policy attention on mobility, housing, the built environment and services. To examine the phenomenon of age friendly policy adoption by cities and the magnitude of adoption, a 21-question web-based survey was administered to a sample of 1,050 cities from the U.S. Census having a population over 10,000 and having at least 14% of their population aged 65 years and over. The goal of the questionnaire was to help identify what kind of policy objectives cities establish to facilitate the opportunity for older adults to live healthy and independent lives in their communities as they age. Multiple linear and ordinal regression models examined the likelihood of policy action by cities and provide evidence as to why some cities support more age friendly policy actions than others. Evidence illustrates theoretical advancement providing support for a cultural model of aging. The cultural model includes multiple factors including bureaucratic responsiveness reflected in the management values of the administration. Findings show variation in the integration of a cultural awareness of aging in the municipality's needs assessment, strategic goals, citizen engagement strategies, and budgetary principles. Cities with a cultural awareness of aging are more likely to adopt age friendly policies. Findings also provide support for the argument that the public administrator is not the driving sole factor in decision making. A shared spaced with mobilized citizen need of individuals 65 and over is identified.
Date: May 2017
Creator: Keyes, Laura Marie
Partner: UNT Libraries

Analysis and Optimization of Graphene FET based Nanoelectronic Integrated Circuits

Description: 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 ...
Date: May 2016
Creator: Joshi, Shital
Partner: UNT Libraries

Application of Cyclic Polarization of Aluminum 3003 Used in All-Aluminum Microchannel Heat Exchangers

Description: All-aluminum microchannel heat exchangers are designed to significantly reduce refrigerant charge requirements, weight, reduced brazed joints, and decreased potential for leakage by increasing reliability. Al 3003 alloy is corrosion resistant and can be formed, welded, and brazed but the issue with all-aluminum heat exchangers is localized corrosion (pitting) in corrosive environments. Currently, there is no universally accepted corrosion test that all coil manufacturers use to characterize their products. Electrochemical testing method of cyclic polarization was employed in this investigation and relevant parameters including electrolyte corrosive agent and its concentration, electrolyte pH, and applied potential scan rate was varied to find an optimal set of parameters. Results of cyclic polarization of Al 3003 in electrolytes containing various concentrations of NaCl were compared with those of the tests in Sea Water Acidified Accelerated Test (SWAAT) electrolyte and it is shown the SWAAT electrolyte (4.2% sea salt acidified to pH of 2.9) is by far stronger (in terms of corrosivity) than typical 3.5% NaCl solution used in most corrosion testing. Corrosion rates (g/m2yr) of Al 3003 measured in this investigation were comparable to those provided by ISO 9223 standard corresponding to C1 through CX categories. Duration of cyclic polarization test is much shorter than that of SWAAT and results obtained in this test is more reproducible compared to those of SWAAT. Scanning electron microscopy micrographs show typical pit depths of about 50 μm.
Date: May 2015
Creator: Barnes, Javier
Partner: UNT Libraries

Assessing Social Determinants of Severe Mental Illness in High-Risk Groups

Description: The primary objective of this research was to explore the impact of possible social factors on non-institutionalized adults 18 years of age or older residing in the United States who exhibited severe mental illness (SMI). A holistic sociological model was developed to explain SMI by incorporating elements of social learning theory, social disorganization theory, and gender socialization theory with social demographic factors. Based on the holistic sociological model, the following factors were investigated: demographic aspects of age, education, income and gender; gender socialization; influence of neighborhood area; social network influence based on communication and interaction among peers and family members; and socially deviant behaviors such as frequently smoking cigarettes, drinking alcohol and using drugs specifically marijuana. The impact of these factors on SMI was examined. A sample of 206 respondents drawn from National Survey on Drug Use and Health, 2003 was assessed. These respondents had answered all the questions related to SMI; social deviant behaviors; neighborhood environment; and communications among peers, family members and friends; and the other studied factors. Ordinary linear regression with interaction terms was employed as a statistical tool to assess the impact of social determinants on SMI. Being female, living a disorganized neighborhood, and frequent and high levels of smoking cigarettes and drinking alcohol had a significant influence on SMI. This reevaluation and reexamination of the role of gender socialization path, socially deviant behaviors like smoking and drinking, and community construction on SMI provided additional insights. This research is one of the first to develop a more holistic sociological model on SMI and explored the previously untested interactive relationships. The limitations of this study suggest the need to test a potential recursive research model and explore additional bi-directional associations.
Date: May 2014
Creator: Sun, Qi
Partner: UNT Libraries

Association of Personality Facets with Unique Dimensions of PTSD

Description: The present study aims to examine which maladaptive and Big Five personality traits, as well as which lower order facets, are related to symptoms specific to PTSD (i.e., intrusions and avoidance). Unique effects were isolated by controlling for nonspecific general depression that occurs in the disorder but is not specific to it. 707 undergraduate students were administered a self-report online survey to assess their personality, trauma history, PTSD and mood symptoms. Additionally, data from 536 9/11 World Trade Center (WTC) responders who have been administered personality, PTSD, and mood surveys as part of a longitudinal study were analyzed. As expected, neuroticism was highly correlated with PTSD, but had fewer associations with PTSD dimensions after controlling for depression. Trust and agreeableness emerged as important, being negatively related to PTSD, while most maladaptive personality domains and facets were positively related to PTSD (perceptual dysregulation had the highest association). Other traits, such as antagonism and openness, were not significantly related to PTSD. There is growing evidence that clinical interventions can change personality traits; the present study provides new personality targets for intervention that are uniquely related to PTSD.
Date: May 2018
Creator: Shteynberg, Yuliya A
Partner: UNT Libraries

Automated Tree Crown Discrimination Using Three-Dimensional Shape Signatures Derived from LiDAR Point Clouds

Description: Discrimination of different tree crowns based on their 3D shapes is essential for a wide range of forestry applications, and, due to its complexity, is a significant challenge. This study presents a modified 3D shape descriptor for the perception of different tree crown shapes in discrete-return LiDAR point clouds. The proposed methodology comprises of five main components, including definition of a local coordinate system, learning salient points, generation of simulated LiDAR point clouds with geometrical shapes, shape signature generation (from simulated LiDAR points as reference shape signature and actual LiDAR point clouds as evaluated shape signature), and finally, similarity assessment of shape signatures in order to extract the shape of a real tree. The first component represents a proposed strategy to define a local coordinate system relating to each tree to normalize 3D point clouds. In the second component, a learning approach is used to categorize all 3D point clouds into two ranks to identify interesting or salient points on each tree. The third component discusses generation of simulated LiDAR point clouds for two geometrical shapes, including a hemisphere and a half-ellipsoid. Then, the operator extracts 3D LiDAR point clouds of actual trees, either deciduous or evergreen. In the fourth component, a longitude-latitude transformation is applied to simulated and actual LiDAR point clouds to generate 3D shape signatures of tree crowns. A critical step is transformation of LiDAR points from their exact positions to their longitude and latitude positions using the longitude-latitude transformation, which is different from the geographic longitude and latitude coordinates, and labeled by their pre-assigned ranks. Then, natural neighbor interpolation converts the point maps to raster datasets. The generated shape signatures from simulated and actual LiDAR points are called reference and evaluated shape signatures, respectively. Lastly, the fifth component determines the similarity between evaluated and reference shape ...
Date: May 2018
Creator: Sadeghinaeenifard, Fariba
Partner: UNT Libraries

Becoming Successful in Education: Beating the Odds, Despite a Background Entrenched in Poverty

Description: The purpose of this study was to investigate the impact of three relationships on academic achievement in mathematics in students of poverty. The three factors that were examined included: teacher-student relationships, parent-student relationships and peer- student relationships. The driving question for the research was as follows: Do external factors such as teacher-student relationships, parent-student relationships and peer-student relationships lead to academic success for students of poverty? The study employed a non-experimental, quantitative approach and utilized longitudinal data from a national database High School Longitudinal Study (HSLS) used a sample of 944 public and private high schools across the USA. A total 0f 28,240 were represented in the survey. Of these 28,240 students, 2641 were used in this study as identified by parental income below the poverty threshold. The outcome of the study indicated that there was little or no correlation between the three relationships and mathematics achievement (academic success). Correlations between the dependent variable (math achievement) and the independent variables even though some were statistically significant their weights had no concrete significance. The study recommends that several initiatives can be instated in schools to support and enhance academic achievement in students of poverty.
Date: May 2017
Creator: Thompson, Pauline A
Partner: UNT Libraries

Belief Transfers in Co-branding and Brand Extension and the Roles of Perceptual Fit

Description: Existing co-branding and brand extension research generally coalesces around two important constructs: perceptual fit and attitude toward the brand. Studies in co-branding and brand extension to date have generally emphasized the transference of affective elements of attitude from parent brand to the extension. Researchers and practitioners clearly need to learn more about the transfer of belief, the cognitive elements of attitude. Too little is currently known about whether and how beliefs are actually transferred in co-branding and brand extension applications, particularly in terms of perceptual fit. This dissertation investigates belief transfer and the effect of perceptual fit on belief transfer in co-branding and brand extension scenarios and develops answers to the following research questions: 1.Are different categories of beliefs transferable from parent brand to theextension? 2.How do various sub-dimensions of perceptual fit affect belief transfers fromparent brands to the extension? 3.How do different categories of beliefs affect consumers’ intentions to purchasethe extension products? Categorization Theory was used as the fundamental theory to build the hypotheses. This dissertation involved qualitative studies, belief scale development, and experimental design studies. The results revealed that aesthetic and functional beliefs are positively transferred from parent brand to the extension. The transfer of aesthetic beliefs is affected by the level of brand fit while the transfer of functional beliefs is independent upon the level of any perceptual fit construct. Finally, cognitive structure based on the strength of extension beliefs is more predictive upon the purchase intention. Findings will extend the co-branding and brand extension literature, especially in terms of the pattern of belief transfers that unfold subject to the influence of various perceptual fit constructs. The results will also provide additional insights about the role that perceptual fit plays in influencing categories of consumer beliefs as those beliefs are also influenced by the specific perceptual fits ...
Date: May 2015
Creator: Roswinanto, Widyarso
Partner: UNT Libraries

Bioinspired and biocompatible coatings of poly(butylene adipate-co-terephthalate) and layer double hydroxide composites for corrosion resistance

Description: 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.
Date: May 2016
Creator: Rizvi, Syed Hussain
Partner: UNT Libraries

Biomass-Derived Activated Carbon through Self-Activation Process

Description: 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.
Date: May 2016
Creator: Xia, Changlei
Partner: UNT Libraries

Brain Computer Interface (BCI) Applications: Privacy Threats and Countermeasures

Description: In recent years, brain computer interfaces (BCIs) have gained popularity in non-medical domains such as the gaming, entertainment, personal health, and marketing industries. A growing number of companies offer various inexpensive consumer grade BCIs and some of these companies have recently introduced the concept of BCI "App stores" in order to facilitate the expansion of BCI applications and provide software development kits (SDKs) for other developers to create new applications for their devices. The BCI applications access to users' unique brainwave signals, which consequently allows them to make inferences about users' thoughts and mental processes. Since there are no specific standards that govern the development of BCI applications, its users are at the risk of privacy breaches. In this work, we perform first comprehensive analysis of BCI App stores including software development kits (SDKs), application programming interfaces (APIs), and BCI applications w.r.t privacy issues. The goal is to understand the way brainwave signals are handled by BCI applications and what threats to the privacy of users exist. Our findings show that most applications have unrestricted access to users' brainwave signals and can easily extract private information about their users without them even noticing. We discuss potential privacy threats posed by current practices used in BCI App stores and then describe some countermeasures that could be used to mitigate the privacy threats. Also, develop a prototype which gives the BCI app users a choice to restrict their brain signal dynamically.
Date: May 2017
Creator: Bhalotiya, Anuj Arun
Partner: UNT Libraries

Case Studies to Learn Human Mapping Strategies in a Variety of Coarse-Grained Reconfigurable Architectures

Description: Computer hardware and algorithm design have seen significant progress over the years. It is also seen that there are several domains in which humans are more efficient than computers. For example in image recognition, image tagging, natural language understanding and processing, humans often find complicated algorithms quite easy to grasp. This thesis presents the different case studies to learn human mapping strategy to solve the mapping problem in the area of coarse-grained reconfigurable architectures (CGRAs). To achieve optimum level performance and consume less energy in CGRAs, place and route problem has always been a major concern. Making use of human characteristics can be helpful in problems as such, through pattern recognition and experience. Therefore to conduct the case studies a computer mapping game called UNTANGLED was analyzed as a medium to convey insights of human mapping strategies in a variety of architectures. The purpose of this research was to learn from humans so that we can come up with better algorithms to outperform the existing algorithms. We observed how human strategies vary as we present them with different architectures, different architectures with constraints, different visualization as well as how the quality of solution changes with experience. In this work all the case studies obtained from exploiting human strategies provide useful feedback that can improve upon existing algorithms. These insights can be adapted to find the best architectural solution for a particular domain and for future research directions for mapping onto mesh-and- stripe based CGRAs.
Date: May 2017
Creator: Malla, Tika Kumari
Partner: UNT Libraries

Catalytic Properties and Mechanical Behavior of Metallic Glass Powders

Description: Lack of crystalline order and microstructural features such as grain/grain-boundary in metallic glasses results in a suite of remarkable attributes including very high strength, close to theoretical elasticity, high corrosion and wear resistance, and soft magnetic properties. By altering the morphology and tuning of composition, MGs may be transformed into high-performance catalytic materials. In this study, the catalytic properties of metallic glass powders were demonstrated in dissociating toxic organic chemicals such as AZO dye. BMG powders showed superior performance compared to state of the art crystalline iron because of their high catalytic activity, durability, and reusability. To enhance the catalytic properties, high energy mechanical milling was performed to increase the surface area and defect density. Iron-based bulk metallic glass (BMG) of composition Fe48Cr15Mo14Y2C15B6 was used because of its low cost and ability to make large surface area by high energy ball milling. AZO dye was degraded in less than 20 minutes for the 9 hours milled Fe-BMG. However, subsequent increase in ball milling time resulted in devitrification and loss of catalytic activity as measured using UV-Visible spectroscopy. Aluminum-based bulk metallic glass (Al-BMG) powder of composition Al82Fe3Ni8Y7 was synthesized by arc-melting the constituent elements followed by gas-atomization. The particle size and morphology were similar to Fe-BMG with a fully amorphous structure. A small percentage of transition metal constituents (Fe and Ni) in a mostly aluminum alloy showed high catalytic activity, with no toxic by-products and no change in surface characteristics. Al-alloy particles, being light-weight, were easily dispersed in aqueous medium and accelerated the redox reactions. The mechanism of dye dissociation was studied using Raman and Infrared (IR) spectroscopy. Breaking of -C-H- and - C-N- bonds of AZO dye was found to be the primary mechanism. Mechanical behavior of individual BMG particles was evaluated by in situ pico-indentation in a scanning electron ...
Date: May 2017
Creator: Garrison, Seth Thomas
Partner: UNT Libraries

Characteristics of Mothers among Counselor Education Faculty

Description: Pre-tenured faculty in higher education and as well as mothers have reportedly struggled with low wellness levels, high demands, little social support, and an imbalance of work and home life. Mothers in higher education and in counselor education have reported struggling with work-life balance, high scholarly productivity, and long hours as well as the emotional and physical energy demands of working with counselors-in-training. A search of the professional literature revealed a paucity of quantitative research regarding demographic characteristics, wellness levels, and social support levels of mothers among counselor education faculty (MCEs). Participants for this study were faculties of counselor education programs recruited from the Holland List of Counseling Programs and from the Council for Accreditation of Counseling and Related Educational Programs online directory. A total of 180 MCEs participated (aged 29-63, with mean age 40.6 years; 83% Caucasian, 8% other, 5% African American, 3% Hispanic, <1% Asian). Results showed that faculty rank did not account for a significant difference among wellness scores of MCEs and that reported social support, tenure or non-tenure track, number of children in the care of MCEs, number of children under age 8, number of publications, and teaching workload accounted for 14% of the variance in wellness levels of MCEs. Specifically, reported higher teaching workload (β = -.194, rs2 = .35, p = .012) and higher social support (β = -.258, rs2 = .36, p = <.001) were found to be significant predictors of lower wellness levels among MCEs, both with small effects. Based on these results, MCEs may benefit from advocating that their departments and universities adapt to their unique needs to improve their levels of wellness and social support through mentoring, which, in turn, may result in not only their own increased productivity but also their students' increased wellness levels.
Date: May 2017
Creator: Jimenez, Kyrstin Anne
Partner: UNT Libraries

Characteristics of Primary Cilia and Centrosomes in Neuronal and Glial Lineages of the Adult Brain

Description: Primary cilia are sensory organelles that are important for initiating cell division in the brain, especially through sonic hedgehog (Shh) signaling. Several lines of evidence suggest that the mitogenic effect of Shh requires primary cilia. Proliferation initiated by Shh signaling plays key roles in brain development, in neurogenesis in the adult hippocampus, and in the generation of glial cells in response to cortical injury. In spite of the likely involvement of cilia in these events, little is known about their characteristics. Centrosomes, which are associated with primary cilia, also have multiple influences on the cell cycle, and they are important in assembling microtubules for the maintenance of the cell’s cytoskeleton and cilia. The cilia of terminally differentiated neurons have been previously examined with respect to length, incidence, and receptors present. However, almost nothing is known about primary cilia in stem cells, progenitors, or differentiated glial cells. Moreover, it is not known how the properties of cilia and centrosomes may vary with cell cycle or proliferative potential, in brain or other tissues. This dissertation focuses first on neurogenesis in the hippocampal subgranular zone (SGZ). The SGZ is one of the few brain regions in mammals that gives rise to a substantial number of new neurons throughout adulthood. The neuron lineage contains a progression of identifiable precursor cell types with different proliferation rates. This present study found that primary cilia were present in every cell type in the neuronal lineage in SGZ. Cilium length and incidence were positively correlated among these cell types. Ciliary levels of adenylyl cyclase type III (ACIII) levels relative to ADP-ribosylation factor-like protein 13b (Arl13b) was higher in neurons than in precursor cells and glia, and also changed with the cell cycle. G-protein coupled receptors, SstR3, MCHR1, and Gpr161 receptors were only found in neuronal cilia. The levels ...
Date: May 2015
Creator: Bhattarai, Samip Ram
Partner: UNT Libraries

El Cine De Terror Español Como Espejo De La Cultura Española

Description: This study traces the history and culture of Spain as seen through the lens of the nation´s production of horror cinema. Starting from the boom of Spanish horror film in the early 1960s, the thesis compares and contrasts the political and social aspects of Spanish society throughout three distinct eras of the 20th century: 1962 – 1975 (the boom of Spanish horror film through the Franco dictatorship), 1975 – 1999 (the transition to democracy through the end of the 20th century) and 2000 – present (the 21st century). Movies as diverse as Gritos en la noche (1962, Jesús Franco), ¿Quién puede matar a un niño? (1976, Narciso Ibáñez Serrador) and Angustia (1987, Bigas Luna) are framed by culturally-related anectodes as well as correlations to their respective social environments. Special attention has been paid to the production and release of each film, especially in regards to censorship during the Franco dictatorship. The results show that Spanish horror cinema has acted as a true mirror to culture, society and politics in its native country throughout the 20th century and that this trend will likely extend in to the future.
Date: May 2014
Creator: Donahue, Tyler
Partner: UNT Libraries

Collective Security and Coalition: British Grand Strategy, 1783-1797

Description: On 1 February 1793, the National Convention of Revolutionary France declared war on Great Britain and the Netherlands, expanding the list of France's enemies in the War of the First Coalition. Although British Prime Minister William Pitt the Younger had predicted fifteen years of peace one year earlier, the French declaration of war initiated nearly a quarter century of war between Britain and France with only a brief respite during the Peace of Amiens. Britain entered the war amid both a nadir in British diplomacy and internal political divisions over the direction of British foreign policy. After becoming prime minister in 1783 in the aftermath of the War of American Independence, Pitt pursued financial and naval reform to recover British strength and cautious interventionism to end Britain's diplomatic isolation in Europe. He hoped to create a collective security system based on the principles of the territorial status quo, trade agreements, neutral rights, and resolution of diplomatic disputes through mediation - armed mediation if necessary. While his domestic measures largely met with success, Pitt's foreign policy suffered from a paucity of like-minded allies, contradictions between traditional hostility to France and emergent opposition to Russian expansion, Britain's limited ability to project power on the continent, and the even more limited will of Parliament to support such interventionism. Nevertheless, Pitt's collective security goal continued to shape British strategy in the War of the First Coalition, and the same challenges continued to plague the British war effort. This led to failure in the war and left the British fighting on alone after the Treaty of Campo Formio secured peace between France and its last continental foe, Austria, on 18 October 1797.
Date: May 2017
Creator: Jarrett, Nathaniel W
Partner: UNT Libraries

Community-based Logistics and Supply Chain Management: Developing, Testing and Validating Conceptual Models

Description: 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 ...
Date: May 2016
Creator: Obaze, Yolanda
Partner: UNT Libraries

Community College Student Retention and Completion based on Financial Expenditures and Hispanic-Serving Status

Description: Despite declining community college funding being allocated increasingly on the basis of student success, U.S. community college student retention and completion rates over the past decade have either remained steady or decreased, especially for Latino students. Using descriptive statistics and multiple regression models with secondary data procured from the Integrated Postsecondary Education Data System (IPEDS), I analyzed student success rates—full time student retention and completion rates—based on community college financial allocations and Hispanic-serving institution (HSI) status. To equitably analyze community colleges in the sample (n = 909), I separated them into four groups based on institutional size as defined by the Carnegie Classification. Descriptive results indicated that instructional divisions spent an average of 43% of the college's total allocated budget—often more than three times the allocated budget of any other division. Regression results indicated that instructional expenditures had the most consistent impact on student success regardless of college size and that scholarship expenditures and academic support expenditures generally had a negative impact on student retention and completion rates. Regarding Latino student success in particular, findings indicated that the manner in which colleges allocated their funds impacted only small and medium-sized community colleges. Of the nine different types of institutional expenditures, only student services expenditures and public services expenditures had a statistically significant impact on Latino student success. Additionally regression analysis indicated that community college HSI status did not have a large impact on overall full-time student retention and completion rates but did have a significant impact on full-time Hispanic student retention and completion rates for all institution sizes. Findings of this study confirmed that HSI status does impact Latino student success in public community colleges. This finding is consistent with prior studies on the positive impact of instructional expenditures on student success rates. Further research on the specific elements within ...
Date: May 2017
Creator: DaSilva, Jose E.
Partner: UNT Libraries

A Comparative Evaluation of Functional Analytic Methods

Description: The individual functional analysis (FA) is the most widely used method to identify variables that influence the occurrence of problem behavior. Researchers often modify the FA after the analysis reveals undifferentiated responding. The interview-informed synthesized contingency analysis (IISCA) is one of the most substantial variations of the FA that builds upon the FA modifications. We evaluated the use of the two different functional analytic methods, the FA and IISCA, and the subsequent function-based treatment to reduce problem behavior for three children with autism spectrum disorder (ASD). The individual FA and the IISCA demonstrated differentiated responding for all participants. The treatment based on the results from the traditional FA was effective for all children. We discuss the implications of these findings.
Date: May 2018
Creator: Perkins, Crysta
Partner: UNT Libraries

Comparison of Heterogeneity and Heterogeneity Interval Estimators in Random-Effects Meta-Analysis

Description: Meta-analyses are conducted to synthesize the quantitative results of related studies. The random-effects meta-analysis model is based on the assumption that a distribution of true effects exists in the population. This distribution is often assumed to be normal with a mean and variance. The population variance, also called heterogeneity, can be estimated numerous ways. Accurate estimation of heterogeneity is necessary as a description of the distribution and for determining weights applied in the estimation of the summary effect when using inverse-variance weighting. To evaluate a wide range of estimators, we compared 16 estimators (Bayesian and non-Bayesian) of heterogeneity with regard to bias and mean square error over conditions based on reviews of educational and psychological meta-analyses. Three simulation conditions were varied: (a) sample size per meta-analysis, (b) true heterogeneity, and (c) sample size per effect size within each meta-analysis. Confidence or highest density intervals can be calculated for heterogeneity. The heterogeneity estimators that performed best over the widest range of conditions were paired with heterogeneity interval estimators. Interval estimators were evaluated based on coverage probability, interval width, and coverage of the estimated value. The combination of the Paule Manel estimator and Q-Profile interval method is recommended when synthesizing standardized mean difference effect sizes.
Date: May 2018
Creator: Boedeker, Peter
Partner: UNT Libraries