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 Collection: UNT Theses and Dissertations
Application of Cyclic Polarization of Aluminum 3003 Used in All-aluminum Microchannel Heat Exchangers

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

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Date: May 2015
Creator: Barnes, Javier
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 ...
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Belief Transfers in Co-branding and Brand Extension and the Roles of Perceptual Fit

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

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Date: May 2015
Creator: Roswinanto, Widyarso
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 ...
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Characteristics of Primary Cilia and Centrosomes in Neuronal and Glial Lineages of the Adult Brain

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

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Date: May 2015
Creator: Bhattarai, Samip Ram
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 ...
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Determinants of Citizens’ 311 Use Behaviors: 311 Citizen-initiated Contact, Contact Channel Choice, and Frequent Use

Determinants of Citizens’ 311 Use Behaviors: 311 Citizen-initiated Contact, Contact Channel Choice, and Frequent Use

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Date: May 2015
Creator: Wu, Wei-Ning
Description: Facing increasingly complex policy issues and diminishing citizen satisfaction with government and service performance, managing the quality of citizen relationship management has become a main challenge for public managers. Solutions to complex policy problems of service performance and low level of citizen participation often must be developed by encouraging citizens to make their voices heard through the various participation mechanisms. Reflecting on this need, the municipal governments in the U.S. have developed centralized customer systems for citizen relationship management. 311 centralized customer system (named 311 in this study) has the functions of citizen-initiated contact, service-coproduction, and transaction, and many local governments launch 311 to maintain or enhance their relationship with the public. Using 311 is an easy and free technically for citizens, but ensuring some degree of citizen engagement and citizens’ 311 use has been challenging for local public managers of municipalities. Despite calls for the importance of 311 in the service and information delivery process, fair treatment and access to use of governmental information, citizen participation, government responsiveness, and citizen satisfaction, to the best of our understanding, no empirical studies explore citizens’ 311 behaviors in the micro and individual level in the field of public administration. This dissertation provides ...
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The Effect of Curcumin Supplementation on Physical and Biological Indices of Delayed Onset Muscle Soreness and Inflammation Following Muscle Injury

The Effect of Curcumin Supplementation on Physical and Biological Indices of Delayed Onset Muscle Soreness and Inflammation Following Muscle Injury

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Date: May 2015
Creator: Venable, Adam Steven
Description: In this project, the effects of dietary polyphenols on exercise-induced muscle damage and vascular health are examined. Dietary polyphenols exert well-known anti-inflammatory effects; however, how these effects are realized with respect to vascular health and EIMD is relatively unknown. I begin by reviewing the available literature surrounding the impact of three dietary polyphenols (curcumin, catechins, and quercetin) on inflammation associated with EIMD. It is well established that their primary means of anti-inflammation is through alterations of NF-κB and AP-1 transcription activities. Given this, their inclusion into training strategies seems reasonable. Consistent evidence is presented making a case for the anti-inflammatory effects of dietary polyphenols following EIMD. I follow this review up by completing an in-depth study on the consumption of curcumin prior to EIMD. I found curcumin (1000 mg/day) can reduce subjective soreness and decrease inflammation compared to placebo controls. To further understand the effects of dietary polyphenols on health, I investigate the effects of a four-week supplementation period of cocoa (catechins) on vascular. I concluded that atherogenic risk in obese women is reduced after consumption of cocoa. In addition to these experimental projects, I developed two novel methods that can be used to investigate vascular health (EMP concentration) and ...
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Effects of Auditor-provided Tax Services on Book-tax Differences and Investors’ Mispricing of Book-tax Differences

Effects of Auditor-provided Tax Services on Book-tax Differences and Investors’ Mispricing of Book-tax Differences

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Date: May 2015
Creator: Luo, Bing
Description: In this study, I investigate the effect of auditor-provided tax services (ATS) on firms’ levels of book-tax differences and investors’ mispricing of book-tax differences. The joint provision of audit and tax services has been a controversial issue among regulators and academic researchers. Evidence on whether ATS improve or impair the overall accounting quality is inconclusive as a result of the specific testing circumstances involved in different studies. Book-tax differences capture managers’ earnings management and/or tax avoidance intended to maximize reported financial income and to minimize tax expense. Therefore, my first research question investigates whether ATS improve or impair audit quality by examining the relation between ATS and firms’ levels of book-tax differences. My results show that ATS are negatively related to book-tax differences, suggesting that ATS improve the overall audit quality and reduce aggressive financial and/or tax reporting. My second research question examines whether the improved earnings quality for firms acquiring ATS leads to reduced mispricing of book-tax differences among investors. Recent studies document that despite the rich information about firms’ future earnings contained in book-tax differences, investors process such information inefficiently, leading to systematic pricing errors among firms with large book-tax differences. My empirical evidence indicates that ATS mitigate ...
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Explaining Economic Development Strategies Using Product Differentiation Theory: a Reconceptualization of Competition Among City Governments

Explaining Economic Development Strategies Using Product Differentiation Theory: a Reconceptualization of Competition Among City Governments

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Date: May 2015
Creator: Overton, Michael R
Description: Local governments do not operate in a vacuum. Instead, they are part of a complex “polycentric” system of governments where politically autonomous and self-ruled cities compete with one another over taxable wealth. Missing from the scholarship on metropolitan governance is an understanding of the factors driving competition among local governments. The purpose of this dissertation is to fill this gap by examining how interjurisdictional competition over economic development impacts a city’s choice of strategies for attracting business and residential investment and how those strategies affect revenue collection. First, this dissertation examines whether cities, knowing the economic development strategies of their neighboring cities, pursue similar types of businesses? Or do cities strategically target different types of businesses as a way to avoid the negative consequences of competition? Second, this dissertation explores what impact the decision to pursue similar or dissimilar businesses has on the revenue collection of local governments. Using spatial data analysis to analyze a sample of 2,299 cities, this dissertation finds general support for both theoretical frameworks presented. Overall, the findings from both analyses provide unique insights into metropolitan governance and interjurisdictional competition.
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Forward Genetic Characterization of Medicago Truncatula Tnt1 Insertion Mutants Defective in Nodule Development and Symbiotic Nitrogen Fixation

Forward Genetic Characterization of Medicago Truncatula Tnt1 Insertion Mutants Defective in Nodule Development and Symbiotic Nitrogen Fixation

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Date: May 2015
Creator: Kadel, Khem L.
Description: Legumes are unique plants because they form special structures “nodules”, via symbiotic relationships with rhizobial bacteria present in the soil. Once rhizobia mature inside nodules, they fix atmospheric nitrogen providing a source of bioavailable nitrogen to the plant. To discover novel genetic components involved in the legume-rhizobia symbiosis by using forward genetic screening, we have isolated Medicago truncatula Tnt1 insertion mutants in the R108 ecotype, which are defective in nodule development and symbiotic nitrogen fixation in response to Sinorhizobium meliloti. Out of three mutants NF11044, NF11217 and NF8324, one of the mutants showed brown nodules and Fix- phenotype that is defective in symbiotic nitrogen fixation. The other two mutants showed white nodules and Fix- phenotype, also indicator of defects in symbiotic nitrogen fixation. To identify the underlying mutation causing the phenotype, we have developed molecular genetic markers by obtaining genomic sequences flanking the Tnt1 insertions by TAIL-PCR and Illumina sequencing. To carry out co-segregation analysis, back-crossed BC1F2 segregating populations were obtained. These are being phenotyped, genotyped and analyzed for co-segregation of the phenotype with the Tnt1 genetic markers. Back-crossing also has the effect of reducing the Tnt1 insertions, which are not linked to the nodulation defective phenotypes. Out of the ...
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Friendship, Politics, and the Good in Aristotle's Nicomachean Ethics

Friendship, Politics, and the Good in Aristotle's Nicomachean Ethics

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Date: May 2015
Creator: Pascarella, John Antonio
Description: In Aristotle's Nicomachean Ethics, Books VIII and IX provide A philosophic examination of friendship. While these Books initially appear to be non sequiturs in the inquiry, a closer examination of the questions raised by the preceding Books and consideration of the discussion of friendship's position between two accounts of pleasure in Books VII and X indicate friendship's central role in the Ethics. In friendship, Aristotle finds a uniquely human capacity that helps readers understand the good is distinct from pleasure by leading them to think seriously about what they can hold in common with their friends throughout their lives without changing who they are. What emerges from Aristotle's account of friendship is a nuanced portrait of human nature that recognizes the authoritative place of the intellect in human beings and how its ability to think about an end and hold its thinking in relation to that end depends upon whether it orders or is ordered by pleasures and pains. Aristotle lays the groundwork for this conclusion throughout the Ethics by gradually disclosing pleasures and pains are not caused solely by things we feel through the senses, but by reasoned arguments and ideas as well. Through this insight, we can begin ...
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Manipulations of Sucrose/proton Symporters and Proton-pumping Pyrophosphatase Lead to Enhanced Phloem Transport But Have Contrasting Effects on Plant Biomass

Manipulations of Sucrose/proton Symporters and Proton-pumping Pyrophosphatase Lead to Enhanced Phloem Transport But Have Contrasting Effects on Plant Biomass

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Date: May 2015
Creator: Khadilkar, Aswad S
Description: Delivery of photoassimilate, mainly sucrose (Suc) from photoautotrophic source leaves provides the substrate for the growth and maintenance of sink tissues such as roots, storage tissues, flowers and fruits, juvenile organs, and seeds. Phloem loading is the energized process of accumulating solute in the sieve element/companion cell complex of source leaf phloem to generate the hydrostatic pressure that drives long-distance transport. In many plants this is catalyzed by Suc/Proton (H+) symporters (SUTs) which are energized by the proton motive force (PMF). Overexpression of SUTs was tested as means to enhance phloem transport and plant productivity. Phloem specific overexpression of AtSUC2 in wild type (WT) tobacco resulted in enhanced Suc loading and transport, but against the hypothesis, plants were stunted and accumulated carbohydrates in the leaves, possibly due to lack of sufficient energy to support enhanced phloem transport. The energy for SUT mediated phloem loading is provided from the PMF, which is ultimately supplied by the oxidation of a small proportion of the loaded photoassimilates. It was previously shown that inorganic pyrophosphate (PPi) is necessary for this oxidation and overexpressing a proton-pumping pyrophosphatase (AVP1) enhanced both shoot and root growth, and augmented several energized processes like nutrient acquisition and stress responses. ...
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