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 Collection: UNT Theses and Dissertations
Diabetes Status of Mexican Americans: Impact of Country of Birth

Diabetes Status of Mexican Americans: Impact of Country of Birth

Date: December 2014
Creator: Douglas, Megan E.
Description: In order to better tailor treatment to specific populations, factors which contribute to health disparities among different racial/ethnic groups must be examined. Among Mexican American individuals, the high rate of diabetes represents a significant contributor to overall health. The present study focuses on factors affecting diabetes status among Mexican Americans born in either Mexico or the United States using the 2007 – 2008 NHANES data set. Comparisons were made between diabetes status based on self-report and clinical classification using HbA1c. Results indicated that within the diabetic subsample, Mexican Americans born in Mexico were twice as likely to be incorrectly classified as non-diabetic, when they actually were diabetic, when using a self-report method. In contrast, nativity did not result in differences in diabetes incidence using the HbA1c clinical cut-score diagnostic classification. Age, BMI, gender, nativity, and health insurance coverage were found to have varying relationships to diabetes prevalence and HbA1c levels, but time in the U.S. for Mexico-born individuals was not found to uniquely predict diabetes incidence. Analyses also demonstrated that Mexico-born males, as compared to the other groups, had significantly higher HbA1c levels. Further research is necessary to better understand the relationships among these factors. However, findings do demonstrate a ...
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Direct Immersion Cooling Via Nucleate Boiling of Hfe-7100 Dielectric Liquid on Hydrophobic and Hydrophilic Surfaces

Direct Immersion Cooling Via Nucleate Boiling of Hfe-7100 Dielectric Liquid on Hydrophobic and Hydrophilic Surfaces

Date: December 2014
Creator: Joshua, Nihal E
Description: This study experimentally investigated the effect of hydrophobic and hydrophilic surfaces characteristics on nucleate boiling heat transfer performance for the application of direct immersion cooling of electronics. A dielectric liquid, HFE – 7100 was used as the working fluid in the saturated boiling tests. Twelve types of 1-cm2 copper heater samples, simulating high heat flux components, featured reference smooth copper surface, fully and patterned hydrophobic surface and fully and patterned hydrophilic surfaces. Hydrophobic samples were prepared by applying a thin Teflon coating following photolithography techniques, while the hydrophilic TiO2 thin films were made through a two step approach involving layer by layer self assembly and liquid phase deposition processes. Patterned surfaces had circular dots with sizes between 40 – 250 μm. Based on additional data, both hydrophobic and hydrophilic surfaces improved nucleate boiling performance that is evaluated in terms of boiling incipience, heat transfer coefficient and critical heat flux (CHF) level. The best results, considering the smooth copper surface as the reference, were achieved by the surfaces that have a mixture of hydrophobic/hydrophilic coatings, providing: (a) early transition to boiling regime and with eliminated temperature overshoot phenomena at boiling incipience, (b) up to 58.5% higher heat transfer coefficients, and (c) ...
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Effects of a Water Conservation Education Program on Water Use in Single-family Homes in Dallas, Texas

Effects of a Water Conservation Education Program on Water Use in Single-family Homes in Dallas, Texas

Date: December 2014
Creator: Serna, Victoria Faubion
Description: The City of Dallas Environmental Education Initiative (EEI) is a hands-on, inquiry-based, K-12 water conservation education program that teaches students concepts about water and specific water conservation behaviors. Few descriptions and evaluations, especially quantitative in nature, of water conservation education programs have previously been conducted in the literature. This research measured the quantitative effects and impacts of the education program on water use in single-family homes in Dallas, Texas. A total of 2,122 students in 104 classrooms at three schools in the Dallas Independent School District received hands-on, inquiry-based water conservation education lessons and the average monthly water use (in gallons) in single-family homes was analyzed to measure whether or not there was a change in water use. The results showed that over a period of one calendar year the water use in the single-family homes within each school zone and throughout the entire research area in this study experienced a statistically significant decrease in water use of approximately 501 gallons per home per month (independent, t-test, p>0.001). Data from this research suggests that EEI is playing a role in decreasing the amount of water used for residential purposes. Additionally, this research demonstrates the use of a quantitative tool by ...
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The Effects of Model Prompts on Joint Attention Initiations in Children with Autism

The Effects of Model Prompts on Joint Attention Initiations in Children with Autism

Date: December 2014
Creator: James-Kelly, Kimberly L
Description: The general purpose of the current study was to evaluate the effects of minimally intrusive prompting procedures and preferred stimuli on protodeclarative joint attention initiations in children diagnosed with autism spectrum disorder (ASD). Two boys and one girl diagnosed with ASD participated. The experimenter provided attention and social interaction following protodeclarative initiations throughout all phases of the study. During intervention, a model prompt was delivered every 30 s if the participant failed to initiate a bid for joint attention. Results for the first participant show that a model prompt was sufficient to increase the rate of protodeclarative initiations across stimulus sets. Generalization was seen across sets, but not across environments. Subsequently, the model prompt was sufficient to increase the rate of protodeclarative initiations across sets in a second setting (classroom). Results for the second participant are inconclusive. Data collected during the initial baseline condition show that she engaged in an incompatible verbal response across sets. When pictorial stimuli depicting highinterest items and activities were introduced, the rate of protodeclarative initiations increased over time. We then returned to original baseline condition and saw an initial decrease, followed by a steady increase in the rate of protodeclarative initiations. The third participant withdrew ...
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Effects of Non-homogenous Population Distribution on Smoothed Maps Produced Using Kernel Density Estimation Methods

Effects of Non-homogenous Population Distribution on Smoothed Maps Produced Using Kernel Density Estimation Methods

Date: December 2014
Creator: Jones, Jesse Jack
Description: Understanding spatial perspectives on the spread and incidence of a disease is invaluable for public health planning and intervention. Choropleth maps are commonly used to provide an abstraction of disease risk across geographic space. These maps are derived from aggregated population counts that are known to be affected by the small numbers problem. Kernel density estimation methods account for this problem by producing risk estimates that are based on aggregations of approximately equal population sizes. However, the process of aggregation often combines data from areas with non-uniform spatial and population characteristics. This thesis presents a new method to aggregate space in ways that are sensitive to their underlying risk factors. Such maps will enable better public health practice and intervention by enhancing our ability to understand the spatial processes that result in disparate health outcomes.
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Effects of Sertraline Exposure on Fathead Minnow (Pimephales Promelas) Steroidogenesis

Effects of Sertraline Exposure on Fathead Minnow (Pimephales Promelas) Steroidogenesis

Date: December 2014
Creator: Carty, Dennis R
Description: Sertraline is a selective serotonin reuptake inhibitor (SSRI) that is widely used for the treatment of depression and anxiety. Due to the abundant therapeutic use of sertraline, low levels have been detected in municipal wastewater effluents suggesting that aquatic organisms may be exposed. The purpose of this study was to evaluate the steroidogenic effects of sertraline on larval (FHM) and adult female fathead minnows (FFHM), Pimephales promelas. Larval FHM were exposed to 0.1, 1, and 10 µg/L sertraline for 28 days and analyzed via RT-qPCR for differential expression of 11β-Hydroxysteroid dehydrogenase (11β-HSD), 20β-Hydroxysteroid dehydrogenase (20β-HSD), aromatase (CYP19), and nuclear thyroid receptor alpha (TRα). FFHM were exposed to 3 or 10 µg/L sertraline for 7 days with the brain and ovary excised at exposure termination. Juvenile FHM exposed to 0.1 μg/L sertraline had a significant upregulation of both 20β-HSD and TRα. FFHM exposed to 10 µg/L sertraline had a significant upregulation of 11β-HSD expression in brain tissue, while no steroidogenic changes were observed in the FFHM ovary. Similarly, in FFHM brain tissue, CYP19 and 20β-HSD expression levels were significantly higher in fish exposed to 10µg/L sertraline compared to control. The significance of these findings with respect to survival, growth and reproduction ...
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Electoral Rules, Political Parties, and Peace Duration in Post-conflict States

Electoral Rules, Political Parties, and Peace Duration in Post-conflict States

Date: December 2014
Creator: Kisin, Tatyana Tuba Kelman
Description: This dissertation examines the following research question: Which types of electoral rules chosen in post-conflict states best promote peace? And are those effects conditional upon other factors? I argue that the effects are conditional upon the types of political parties that exist in the post-conflict environment. Although this explanation is contrary to scholars that speak of political parties as products of the electoral system, political parties often predate the choice of electoral system. Especially in post-conflict states, political parties play an important role in the negotiation process and hence in the design of the electoral rules. I argue that the effects of electoral rules on peace duration are mitigated by the degree to which a party system is broad (nonexclusive) or narrow (exclusive). I develop a theoretical model that led to three hypotheses focusing on the independent role that political parties play in mitigating the effects of electoral rules on peace duration. To test these hypotheses, I use the Cox proportional hazard model on 57 post-conflict states from 1990 to 2009 and had competitive elections. The empirical results show support for the main argument of this study. First, the findings show that electoral rules alone do not increase or decrease ...
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Electrical Conduction Mechanisms in the Disordered Material System P-type Hydrogenated Amorphous Silicon

Electrical Conduction Mechanisms in the Disordered Material System P-type Hydrogenated Amorphous Silicon

Date: December 2014
Creator: Shrestha, Kiran
Description: The electrical and optical properties of boron doped hydrogenated amorphous silicon thin films (a-Si) were investigated to determine the effect of boron and hydrogen incorporation on carrier transport. The a-Si thin films were grown by plasma enhanced chemical vapor deposition (PECVD) at various boron concentrations, hydrogen dilutions, and at differing growth temperatures. The temperature dependent conductivity generally follows the hopping conduction model. Above a critical temperature, the dominant conduction mechanism is Mott variable range hopping conductivity (M-VRH), where p = ¼, and the carrier hopping depends on energy. However, at lower temperatures, the coulomb interaction between charge carriers becomes important and Efros-Shklosvkii variable hopping (ES-VRH) conduction, where p=1/2, must be included to describe the total conductivity. To correlate changes in electrical conductivity to changes in the local crystalline order, the transverse optical (TO) and transverse acoustic (TA) modes of the Raman spectra were studied to relate changes in short- and mid-range order to the effects of growth temperature, boron, and hydrogen incorporation. With an increase of hydrogen and/or growth temperature, both short and mid-range order improve, whereas the addition of boron results in the degradation of short range order. It is seen that there is a direct correlation between the ...
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Electromagnetic Shielding Properties of Iron Oxide Impregnated Kenaf Bast Fiberboard

Electromagnetic Shielding Properties of Iron Oxide Impregnated Kenaf Bast Fiberboard

Date: December 2014
Creator: Ding, Zhiguang
Description: The electromagnetic shielding effectiveness of kenaf bast fiber based composites with different iron oxide impregnation levels was investigated. The kenaf fibers were retted to remove the lignin and extractives from the pores in fibers, and then magnetized. Using the unsaturated polyester and the magnetized fibers, kenaf fiber based composites were manufactured by compression molding process. The transmission energies of the composites were characterized when the composite samples were exposed under the irradiation of electromagnetic (EM) wave with a changing frequency from 9 GHz to 11 GHz. Using the scanning electron microscope (SEM), the iron oxide nanoparticles were observed on the surfaces and inside the micropore structures of single fibers. The SEM images revealed that the composite’s EM shielding effectiveness was increased due to the adhesion of the iron oxide crystals to the kenaf fiber surfaces. As the Fe content increased from 0% to 6.8%, 15.9% and 18.0%, the total surface free energy of kenaf fibers with magnetizing treat increased from 44.77 mJ/m2 to 46.07 mJ/m2, 48.78 mJ/m2 and 53.02 mJ/m2, respectively, while the modulus of elasticity (MOE) reduced from 2,875 MPa to 2,729 MPa, 2,487 MPa and 2,007 MPa, respectively. Meanwhile, the shielding effectiveness was increased from 30-50% to 60-70%, ...
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Ethnic Differences in Caregiving Style

Ethnic Differences in Caregiving Style

Date: December 2014
Creator: Rodriguez, R. Mishelle
Description: This study explored the caregiving styles of 306 grandparents raising grandchild across three ethnic groups (164 European Americans, 65 Latinos, and 77 African Americans). Significant differences were found in caregiving styles between European Americans and African Americans. Caregiver appraisal (burden, satisfaction, and Mastery) was found to be predictive of caregiving style across the entire sample, and differentially by ethnic group. Caregiver style was predictive of grandchild functioning across the entire sample, and differentially by ethnic group. Lastly, caregiver style was found to be predictive of grandparent well-being across the entire sample, and differentially by ethnic group. Implications are discussed in terms of the complex, multidimensional and culturally embedded nature of the caregiving experience and the importance of considering culture for optimal outcomes.
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