Electronic Theses and Dissertations - Open Access

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12588/2237

This collection contains electronic UTSA theses and dissertations (ETDs), primarily from 2005 to present. The collection is not comprehensive; search the UTSA Library Catalog for a complete list of UTSA theses and dissertations.

All of the ETDs in this collection are available to the general public. However, authors are able to request an embargo. Embargoed ETDs will not be downloadable until after their embargo expires.

Authors of these ETDs have retained their copyright while granting UTSA Libraries the non-exclusive right to reproduce and distribute their works.

Former students are invited to broaden access to their thesis or dissertation by making it available in the Open Access collection. To initiate this process, or if you have any questions about the ETD collection, please contact rrpress@utsa.edu.


Recent Submissions

Now showing 1 - 20 of 368
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    Ultra-cold Electrolytic In-situ Resource Utilization (ISRU) for Fuel and Oxygen Production on Mars
    (2023) Chambers, Bradley
    Provisioning a crewed Mars mission from Earth, including 35,000-40,000kg of propellant needed for the return journey, is estimated to require ~400,000kg of propellant (fuel and oxidant) on 4–5 heavy lift launch vehicles. Thus, future crewed Martian missions necessitates “living off the land” through in-situ Resource Utilization (ISRU). The National Aeronautics and Space Administration (NASA) is considering deploying an ISRU electrolyzer 26 months before a human mission to produce 25,000–30,000 kg of oxygen (O2) using atmospheric CO2 abundantly present on Mars. This solid electrolyzer was tested using the Mars Oxygen ISRU-Experiment (MOXIE) device onboard the Perseverance rover. I studied a low-temperature electrolyzer that produces rocket propellant (CH4) and life-supporting oxygen utilizing Martian brines and atmospheric CO2 to remedy the pitfalls of MOXIE. I have completed the framework for this Martian ISRU life-support brine - CO2 electrolyzer by first modelling a hypothetical 10-cell, 100 cm2 electrode-area-per-cell, 50% faradaic efficiency (FE) electrolyzer, which produced 0.45 gW 1day-1 of CH4 and 3.55 gW 1day-1 of O2 at 2V/cell vs. MOXIE’s production of 2.5 gW 1day-1 of O2. This modelling was expanded to alternative configurations for Martian ISRU brine - CO2 electrolysis to produce CO, HCHO, CH3OH, C2H4, and C2H5OH to provide the industrial backbone needed to explore the solar system. Additionally, I have shown that silver wire pseudo-reference electrodes are stable for Martian brine electrochemistry. This electrode was integral to exploring the kinetics of the primary competing hydrogen evolution reaction in ambient Martian temperatures to address the anti-Arrhenius behavior recorded by other groups. The findings herein establish this technology as a promising ISRU methodology for sustainable Martian exploration.
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    Solar Power Generation and Predictions During Rapidly Changing Weather Conditions and Rainfall
    (2023) Marino, Daniele
    This comprehensive study merges two crucial aspects of solar energy predictions and generation: the impact of weather data collection time intervals on solar power predictions and the effects of precipitations on solar power generation and predictions, using advanced machine learning (ML) models. The first part of the study focuses on the challenge of predicting solar energy generation during dynamic weather conditions, particularly at sunrise and sunset, periods with high gradients of weather parameters. By fine-tuning the temporal granularity of weather data (?T), we aim to enhance the forecast accuracy of solar power production, especially during these critical times. This is achieved using Random Forest regression models. The study demonstrates that an optimized ?T can significantly improve prediction accuracy, with up 50% improvements for predictions during sunrise and sunset. The second part of the research addresses the impact of precipitations on solar power production and the accuracy of ML models in predicting solar energy output during events with and without precipitations. Utilizing a comprehensive dataset from Texas, this segment investigates the correlation between solar power output and precipitations, employing statistical error metrics like MSE and MAE. Our findings reveal a noticeable decline in energy yield from solar systems during precipitations and underscore the importance of integrating rainfall data as a predictive feature in the models. By doing so, we demonstrate an improvement in the model's forecasting accuracy, emphasizing the need to consider varying weather conditions in predictive modeling for solar energy. Together, these insights contribute significantly to the field of renewable energy, offering strategies for more effective solar energy harnessing and forecasting.
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    Optimizing Write Buffer Resource Sharing and Reducing Cache-miss Induced Instructions in Simultaneous Multi-threading Processors
    (2023) Sakib, Sudman
    Simultaneous Multi-Threading (SMT) is a processor design technique that offers improved resource utilization and higher instruction throughput by concurrently executing multiple threads and sharing key data path components. Its performance benefit comes from its capacity to dynamically allocate resources to the thread requiring them in each cycle. However, efficient distribution of critical shared resources, such as the write buffer, is essential for optimal performance. Threads characterized by a high incidence of long-latency cache misses dominating the write buffer’s resources can impact system performance. In some instances, the entire write buffer is occupied by store instructions that are all cache miss long latency instructions. Under such circumstances, it’s possible that a specific thread could monopolize the majority of the write buffer resources, leading to stalls for other threads. This thesis project proposes a method that addresses this issue by reducing the number of cache miss store instructions residing in the write buffer. The proposed allocation technique is considered a modification to the commit stage of the default algorithm by imposing a very simple control mechanism on assigning the write buffer entries. Specifically, this is achieved by reserving some write buffer entries for threads that have cache hit store instructions ready to be committed. The proposed method improved system performance on average by 10.5% to 47%, contingent on workload size and system configuration, ensuring fair execution among threads. In summary, the proposed algorithm provides a promising approach to mitigating performance issues related to write buffer utilization in SMT processors.
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    Disparities in Maternal Mortality, Metropolitan Status, and Socioeconomic Conditions in U.S. Counties
    (2023) Olowolaju, Samson Akingbade
    This dissertation explores the geographic differences in maternal mortality ratio in counties in the United States (US). Specifically, the dissertation examines how maternal sociodemographic characteristics and residential socioeconomic conditions such as metropolitan status, residential segregation, social deprivation, income inequality, and obstetric health care availability affect the risk of maternal deaths in US counties. Generalized Linear Bayesian Models (GLBM), including hierarchical Bayesian models, were used to estimate the association between maternal sociodemographic characteristics and residential socioeconomic conditions and maternal mortality risk ratios in US counties. A major conclusion is that non-metropolitan counties have a higher maternal mortality ratio compared to metropolitan counties in the US, even after controlling for maternal sociodemographic characteristics, residential socioeconomic conditions, and health care availability. Particularly, accounting for socioeconomic conditions, including healthcare access, maternal mortality risk ratios are notably elevated in Southern non-metropolitan counties in the United States compared to their counterparts in other regions, except for non-metropolitan counties in the Midwest region. Furthermore, the risk of maternal death during and after pregnancy for older women (aged 30 and above) is higher in non-metropolitan counties compared to urban counties. Moreover, the Isolation of the black population increases the maternal mortality ratio in US counties, controlling for degrees of rurality, social deprivation, and income inequality. Finally, the interaction between residents of different socioeconomic statuses (poor and non-poor) in a county has a protective effect on the maternal mortality ratio.
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    The discourse on educational technology in corporate advertising, landscape reports, and mass media
    (2023) Heinsfeld, Bruna Damiana
    This dissertation aims to critically examine discourses surrounding educational technology from various perspectives, including corporate discourse, educational landscape reports, and media representation. Using discourse analysis as a theoretical framework and methodological approach, this three-essay dissertation explores the discourse in the educational technology sector, the impact of the COVID-19 pandemic on such discourse, and the changing representations of technology in educational settings. The first paper investigates how corporations shape beliefs and perceptions about the role of technology in education through the dimensions of technological optimism, solutionism, and determinism. The second paper focuses on the EDUCAUSE Horizon Report, exploring its discourse on technology in the last three years. The third paper examines representations of technology in The New York Times’ Education section over a five-year period, highlighting the changing discourse surrounding technology integration in educational settings. This dissertation has broad implications for educators, policymakers, and the public in promoting informed perspectives on the role of technology in education. Overall, the three studies included in this work shed light on how corporate advertising, landscape reports, and mass media influence – and often shape – the discourse on educational technology, which calls for a critical analysis of how it is framed, presented, and “sold” to educational stakeholders and decision-makers.
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    Computational Frameworks for Subject-specific Prediction of Vertebral Fracture Risk
    (2023) Prado, Maria
    Aging leads to a significant decrease in bone mineral density (BMD), loss of muscle mass and strength, high risk for falls, and fractures. These musculoskeletal (MSK) changes significantly and negatively affect quality of life. Osteoporosis is a systemic skeletal disease in adults characterized by natural bone loss. Currently, about 20 million Americans over the age of 50 have osteoporosis while the prevalence increased from ∼10 million to >14 million people in 2020. Osteoporosis-related fractures affect nearly 2 million Americans annually and 9 million worldwide. Vertebral fractures, the hallmark of osteoporosis, cause substantial back pain and disability. Dual-energy X-ray absorptiometry (DXA) is the clinical gold-standard imaging technique for the estimation of 2D areal BMD (aBMD) as a surrogate for fracture risk. Quantitative computed tomography (QCT) provides a 3D measure of BMD and can more accurately describe bone heterogeneity and structure, addressing some of the disadvantages of DXA. When QCT is combined with finite element analysis (FEA) it can successfully be used to assess fracture properties of bones such as stiffness and failure loads. Besides bone properties, other can also affect the risk for fracture, including but not limited to spine curvatures and spinal loads. Skeletal muscle mass decline in older individuals can eventually result in altered spine curvature. Evaluation of spine loads can explain how loading on the various spine regions varies with physiological activities and over time, potentially leading to vertebral fractures. To address in vivo measurement challenges, MSK models can be developed to predict the loading of the intersegmental vertebral bodies during daily living activities.
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    Intelligent Signal Smoothing and Cumulative Sum Control Applied to Nuclear Source Search
    (2023) Squire, Michael
    Precise identification of activities associated with the use of nuclear materials – illicit or legal - is the main mission of nuclear security. Data analytics significantly contributes to that cause by recognizing patterns of interest and making inferences. In this thesis one new algorithm involving smoothing is introduced and another method which involves cumulative sum control (CUSUM) is used for abrupt change detection in gamma ray measurements. Such changes may designate activities pertaining to nuclear material, and thus, their fast and accurate detection is of paramount significance. The first method is based on the synergism of fuzzy number and data smoothing to label each datapoint in time series measurements as containing a potential threat or merely noise. The second method simply applies a derivative to a cumulative sum control. The methods were tested using five time series of real-world gamma measurements with infused peaks of varying magnitude and varying location. The ratio of the number of correctly identified peaks is recorded as a number between zero and one inclusive. On average the intelligent smoothing method identified 66.6% of the peaks correctly and the cumulative sum control method identified 83.4% of the peaks correctly.
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    Role of Plasmid Encoded Genes in the Pathopsyiology of Lyme Disease
    (2023) MacMackin, Taylor
    Borrelia burgdorferi (Bb), the tick-borne agent of Lyme disease, is a unique spirochete with limited metabolic capabilities and intimately dependent on host-derived nutrients to alter its gene expression profiles in response to conditions that are highly divergent during its tick and mammalian phases of infection. An array of zinc-dependent transcriptional and post-transcriptional regulators of gene expression have been identified while the intricacies of regulatory changes mediated by zinc as a co-factor during different stages of its infectious life cycle are yet to be fully understood. Bioinformatic and whole genome transcriptional analysis revealed the presence of Borrelia zinc-finger domain containing Protein (BziP) whose role in the patho-physiology of Bb is unknown. My hypothesis is that BziP is linked to housekeeping sigma factor σ70 and is thus essential for Bb’s survival during the tick and mammalian phases of infection. In order to test this hypothesis, constitutive expression of bziP in Bb was achieved by expressing bziP under the control of PflgB-a strong constitutive borrelial promoter using a borrelial shuttle vector pTM61 which also expressed green fluorescent protein to facilitate rapid isolation of transformants. Constitutive expression of bziP results in an increase in the levels of major regulators of gene expression such as BosR and RpoS with a concomitant increase in the levels of several lipoproteins such as Outer surface protein C (OspC) and Decorin Binding Proteins A/B (DbpA/B) critical for transmission, dissemination and survival of Bb in mammalian hosts. BziP contains two conserved CXXC motifs shown to be critical for zinc binding and both these motifs are known to play critical roles in the functions of BziP homologs present in other bacteria. Site-specific changes replacing the cysteine residues of two CXXC (C223SxxC226S and C198SxxC201S) motifs with serines and a histidine at position 202 with alanine (H202A) decreased the levels of BosR, RpoS and OspC. The C198SxxC201S motif and the H202A also show a decrease in expression in BziP itself, indicating that these two site-directed changes destabilize BziP. Phenotypic analysis of the morphology of mutants expressing either the wild type or site directed mutants revealed that spirochetes with three site specific changes have a more elongated rod-shape when compared to the wildtype. Taken together, the constitutive expression of BziP increases the expression of many essential mammalian virulence-related genes and the elongated rod-shaped spirochetes of site specifically altered strains suggest the possibility of BziP playing a key role in motility/morphology of Bb. Based on these phenotypic observations it is likely that BziP could play a critical role in the transmission and infectivity in the mammalian host as both motility/morphology is essential for Bb infection. RNA Seq analysis and infectivity phenotype of these mutants in the C3H/HeN mouse model of Lyme disease will further aid in our understanding of the role of BziP in patho-physiology of Bb.
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    The Development of Leadership Excellence and Global Cultural Intelligence
    (2023) Wengelnik, Cate
    Leadership constructs and leadership development efforts have undergone drastic changes in the last few years. While traditional curricular college leadership development programs on the undergraduate level have focused on top-to-bottom leadership approaches, new, innovative leadership development programs have been incorporated into the management curriculum at some institutions of higher education. The purpose of this qualitative multiple case study was to understand how Senior Business undergraduate students at one research institution of higher education in Texas understand leadership. The research questions for this study were: How do Business college students understand and discuss leadership? In what ways has leadership manifested from the students’ experiences? In this context, student participants who demonstrated leadership experience in- or outside of their educational journey who were in their senior year at the College of Business were included in this study. These student participants were classified as emerging leaders with experience of various leadership constructs in the classroom environment and through on-campus or off-campus leadership engagements. Research data were obtained through semi-structured in-depth interviews and student reflective journals. The findings produced four themes: The participants’ individual leadership practices have been influenced through their environment growing up; the participants’ personality traits have enabled them to succeed as leaders; inclusive leadership practices were grounded in all participant’s leadership philosophy and learning journey as emerging leaders; and the participants understand inclusive leadership in correlation to global cultural intelligence on high-performance teams.
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    Application of Superabsorbent Polymer to Modify Soil Engineering Properties
    (2023) Jafari, Elahe
    Soil moisture content fluctuates considerably due to environmental changes, particularly in clay, which can undergo volume changes and loss of strength with increasing water content. The use of superabsorbent polymer (SAP) as an additive to maintain soil moisture stability is proposed in this study. SAP is non-toxic, vegetation-friendly, and inexpensive, making it suitable for numerous geotechnical applications. The first essay investigates the effect of SAP on the engineering properties of clay through compaction tests and direct shear tests on different ratios of SAP-soil mixtures. The results show that addition of SAP to clay increases the optimum water content of clay and decreases its maximum dry density. At the moistures lower than optimum water content, SAP slightly reduces the cohesion of SAP-soil mixtures while the friction angle remains nearly unchanged. However, both cohesion and friction angle of SAP-soil mixtures improve significantly by raising the SAP ratio in water contents higher than optimum water content. Addition of SAP to soil restricts shear strength fluctuations caused by moisture changes and enhances stability and consistency in the soil's dry density. The second essay establishes the soil-water characteristic curve (SWCC) for soil and different mixtures of soil with SAP to determine the impact of SAP on the suction potential of clay for the suction range of 0-20MPa. Comparing the resulted SWCC for soil and SAP-soil mixtures shows that saturated water holding capacity of clay improves by 860% by adding 2% SAP. When SAP is mixed with soil, it achieves only about 35% of its swelling potential due to the constraining properties of the soil structure, even when the mixture is fully saturated. Among the trained models to predict the suction potential of SAP-soil mixtures, mathematical polynomial interpolation and K-nearest-neighbors (KNN) techniques are shown to have the most accurate predictions based on the R-squared and mean squared error (MSE). In the third essay, an assessment is carried out to determine the Atterberg limits and swelling behavior of soil mixtures containing SAP under various loads. Moreover, this essay investigates the leaching and dissolution properties of SAP, as well as its long-term effectiveness in response to wetting-drying cycles in the field. The Atterberg tests revealed that as the ratio of SAP in the soil mixture increased, both the liquid limit (LL) and plastic limit (PL) rose. The plasticity index (PI) increases exponentially by raising the SAP ratio. The swelling of SAP-soil mixtures increases with SAP ratio. However, applying 20 kPa of normal stress restricts the maximum axial strain to 2.17% for SAP-soil mixtures. The swelling of soil+0.5%SAP under 10 kPa of pressure is simulated using GeoStudio, employing the Finite Element Method by integrating SIGMA/W and SEEP/W. This simulation exhibits a significant correlation with the swelling observed during the experimental phase. The wetting-drying cycle tests reveal that, following five cycles, the SAP exhibits insignificant leaching tendencies from the soil. While the maximum absorbency of SAP in a saturated state declines marginally with each repetition of wetting-drying cycles, the reduction remains consistent after the fourth cycle. As a whole, these essays offer a comprehensive analysis of the potential advantages of utilizing SAP as an additive to maintain soil moisture stability, with a specific emphasis on clay soils.
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    The Role of Fractalkine-mediated Neuroprotection in the Diabetic Retina
    (2023) Rodriguez, Derek
    Diabetic retinopathy (DR) is a leading cause of blindness worldwide due to hallmarks that include neuronal loss, microgliosis, and vasculature damage. Evidence suggests neurodegeneration and neuronal loss precedes vascular dysfunction in early diabetes. Inflammation caused by microglia exacerbates retinal pathology. Microglia, the resident immune cells of the central nervous system (CNS), become activated due to hyperglycemia and are believed to contribute to the development of DR. The microglia-neuronal crosstalk mediated by CX3CR1 and fractalkine (CX3CL1; FKN) signaling provides a neuroprotective environment in several neurological diseases. FKN is a protein expressed on neuronal membranes (mFKN) and undergoes constitutive cleavage to release a soluble domain (sFKN), while the C-terminal fragment (ctFKN), localized in the intracellular face of the cell membrane can translocate to the nucleus of neurons, inducing cell survival. The role by which mFKN, sFKN, and ctFKN regulate retinal function are still unknown. This dissertation is sought to investigate the microglia-neuronal signaling axis (CX3CR1/FKN) in regulating microglial physiology in the diabetic retina and highlighted the contributions of mFKN and sFKN on microglia-mediated inflammation using recombinant adeno-associated viruses (rAAVs), address the contribution of full-length FKN and ctFKN to retinal inflammation in our models of diabetes. Here, we show that prophylactic administration of sFKN, but not mFKN, prevented vascular and neuronal damage, and improved visual acuity in FKN knockout (FKN-KO) mice at onset and early stages of DR. Additionally, therapeutic delivery of sFKN at onset stages DR reversed vascular dysfunction; minimized vascular tortuosity and fibrin(ogen) deposition, enhanced gap- and tight-junction integrity, and visual acuity during early stages of DR. Lastly, we found that FKN is an essential molecule, by which the ctFKN undergoes nuclear localization during diabetes, suggesting to enhance neuronal cell survival and maintenance. Altogether, these data indicate that FKN signaling serve as an alternative pathway to implement translational and therapeutic approaches to minimize retinal pathology and improve neuronal function.
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    Learning the Game: A Narrative Inquiry Into Tenure-Track Black Women Faculty’s Perceptions of Institutional Support
    (2023) Victor, Jasmine
    The first Black woman professor in the U.S. was hired in 1859, yet Black women are still underrepresented in faculty roles and experience the academy in unique ways. While Black women faculty offer special contributions to research, teaching, and service rooted in their Blackness and womanhood; unfortunately, certain barriers to their professional success exist that, if unaddressed, result in their departure from the academy, and therein lies the problem. The purpose of this narrative study was to investigate the ways Black women faculty on the tenure track author their experiences in the academy based on their perceptions of support from the institutions where they work. Using Black feminist thought and perceived organizational support as frameworks, this study’s data was collected through individual interviews and journal entries from six Black women faculty on the tenure track at 4-year Hispanic Serving Institutions (HSIs) in Texas. Four themes emerged from the data: the participants’ (1) foundational narratives, (2) positive perceptions of support, (3) negative perceptions of support, and (4) response to institutional support or the lack thereof. The study’s findings contributed to recommendations that support a change in behavior for higher education administrators, encouragement for new and aspiring Black women faculty on the tenure-track, and the underresearched area of Black women faculty’s experiences at HSIs.
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    Leveraging museum genomics to unravel species boundaries and historical biogeography of nocturnal African primates (Galagidae)
    (2023) Penna, Anna Paula Casselli
    Tropical rainforests harbor most of Earth’s biodiversity, yet our understanding of rainforest biotas remains vastly incomplete. Knowledge gaps on species richness and endemism hamper conservation measures and inferences in ecology and evolution. In the African rainforests, characterizing species diversity and distributions has been challenging owing to sociopolitical, bureaucratic, and logistic impediments. This dissertation employs a museum genomics approach to study primate diversity and evolution in Africa’s western Guinean-Congolian forests and eastern forest mosaics. To this goal, I focus on the broadly distributed yet poorly known galagos, or bushbabies. Chapter 1 reviews the systematics and taxonomy of the family Galagidae and discusses unresolved questions in the clade’s evolution. Chapter 2 examines the mitochondrial DNA diversity of the small-eared greater galagos (Otolemur garnettii), challenging current taxonomic schemes and revealing undescribed diversity. Given challenges to sample wild populations to support genetic work, Chapter 3 develops a framework for the extraction, sequencing, and analysis of DNA sequence data from century-old museum specimens. It then applies this framework for the assessment of exogenous contamination and phylogenetic inference in the whole infraorder Lorisiformes (galagos, lorises, angwantibos, and pottos). Finally, Chapter 4 extends this museomics framework to unravel lineage diversity within western dwarf galagos (Galagoides), employing whole genomes to characterize spatial genetic patterns and their correspondence with morphological divergence among populations. This dissertation illustrates the extraordinary potential of archival DNA to improve knowledge on species diversity, ranges, and speciation. This improved knowledge will support historical biogeography and biodiversity conservation in Africa’s rainforests and beyond.
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    GEOAI for Urban Resilience: Strategic Optimization of Power Grids and Electric Vehicle Fleet Charger Networks
    (2023) Nunez, Ana Marcela
    The accelerating change towards electrification in the transportation sector poses a significant threat to the stability of existing power grid infrastructure. It is necessary to change how utility companies manage their existing assets in the power grid. The unmanaged expansion of EV adoption threatens the power grid stability regarding power loss due to outages, costly updates to the infrastructure, and asset damage during outages. Focusing on the increasing prevalence of Electric Van fleets in the United States, this thesis proposes the integration of Geographic Information Systems and optimization tools to create a secure space for digitally formulating and testing operational algorithms for power grid asset arrangements before implementation in the physical world. The need to rely on Geographic Information Systems (GIS) arises from its capability to generate digital data based on their physical locations. The research breaks down the problem into three subproblems: synthetic data generation and modeling, fleet allocation optimization problem, and strategic path planning for cable installation. The creation of synthetic data for customer demands and feeder capacities and the creation of synthetic distribution feeders mapped to real geospatial topologies solved the problem of exposing sensitive data. The synthetic data provided a viable alternative, allowing us to generate datasets without compromising the privacy of clients and utility companies’ privacy. The optimization model strategically allocates electric vehicle fleets across the power grid, considering customer power demands and feeder capacities while minimizing operational costs. Finally, we propose a path planning for connecting clients to the power grid without affecting the environment. By proposing this comprehensive framework, the thesis aims to contribute to urban infrastrucvi ture’s sustainable and resilient development. The summarized roadmap provides cities worldwide with direction on incorporating electric vehicle fleets into existing power grids, ensuring the increasing demand for electricity doesn’t affect the current power grid clients and infrastructure and maintaining a reliable, cost-effective, and environmentally conscious power grid infrastructure.
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    Culturally Modified Trees in the Southern Blue Mountains of Eastern Oregon
    (2023) Quintanilla, Desiree Cristina
    The purpose of this thesis is to identify factors that play a role in the location of a type of culturally modified tree created by Native Americans, known as cambium peeled trees, within the Malheur National Forest in eastern Oregon. Cambium peeled trees (CPTs) are created by peeling back the outer bark to reach the inner layer of bark called cambium. Over the past 50 years, archaeologists have realized the existence and the importance of CPTs. These trees are living archaeological sites that are susceptible to environmental factors like age, fire, drought and disease and human activities such as logging and defacement. By identifying environmental factors that play a role in the location of CPTs it is possible to identify areas within the Malheur National Forest in which these trees can be located and thus ensure their protection.
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    "[H]ow We Are Supposed to Conduct Ourselves": Crafting Maternal Facultad Counterstories to Contest Mexican-American Master Narratives of Motherhood
    (2023) Chairez, Yvette
    This dissertation sets out to study the ways in which maternal facultad - the embodied, experiential knowledge of Latina mothers - may function as counterstory to the patriarchal master narratives of the legendary foremothers - la Malinche, la Virgen de Guadalupe, and La Llorona - that exist to influence the perceptions of mothers in Mexican/Mexican-American/Latinx cultural texts. Through a borderlands studies lens I conducted a Chicana feminist rhetorical analysis that uncovers and presents the maternal facultad of these mother figures and offers it as counterstory to the master narratives at play in the texts. I have inferred that the following three broad elements of knowledge may faithfully be explored as the foundations of one's maternal facultad in instances where the mother is unable to speak on her maternal facultad herself: 1) testimonios, 2) historical context, and 3) embodied knowledge. I analyzed primarily Mexican-American cultural texts in the genres of literary fiction, life-writing, and art where the master narratives of the foremothers are being applied as frameworks for how the mother-characters/rhetors experiences are understood and expressed. Through my analysis I found that when information from these three elements is stitched together, counterstories take shape that reveal more complete pictures of the mothers' experiences in the corpus I have chosen and, thus, show how the master narratives of the foremothers may be harming these mothers, and the institution of motherhood as a whole.
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    Affordances of STEM-Related Skills at a Nature Preschool: A Multiple Case Study of Children's Engagement in Free Play
    (2023) Mifflin, Melissa M.
    The purpose of this multiple case study was to explore affordances for STEM-related skills in a nature preschool in central Texas. Observations were conducted along with the collection of videos and photographs of four preschool-aged participants. Informal interviews were also implemented during data collection and observations. Semi-formal interviews were performed with the teacher, teaching assistant, and one parent from each of the participants. The three main findings were 1. The creek, by the water, provided a location for observation and stillness, affording more science-related skills than other subjects. 2. Many STEM affordances were in climbable features with mostly math-related skills, followed by science, technology, and engineering-related skills. 3. Graspable/detached objects altered STEM affordances with technology and engineering-related skills happening more than science and math-related skills. Recommendations for future research are to conduct more studies on STEM nature play and research how to increase affordances based on environmental qualities. Implications for administration are to hire high-quality teachers and provide training on the natural environment and emergent curriculum. The community can connect children with native plants and wildlife. Policy should break down barriers based on proximity to nature, disabilities, and socioeconomic status. Children learn through play. Nature play provides affordances for STEM-related skills.
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    Relationship Between Postural Stability and Auditory Processing in Children With Autism Spectrum Disorder
    (2023) Siqueiros, Jesus Emmanuel
    This study investigates the intricate relationship between sensory processing and postural control in children with autism spectrum disorder (ASD), focusing on the influence of auditory noise. Thirty-two children, aged 6-12, participated in playful experiments during a summer camp, including 21 with ASD and 11 typically developing (TD). Utilizing a force plate, participants performed tandem stance under two auditory conditions: heavy rain noise at an intensity of 75-80dB (NOISE) and 43-47dB (NORMAL). Postural stability was assessed through the duration of tandem stance, low- and high-frequency components of center of pressure (CoP) velocity. Sensory difficulties were measured using the Sensory Processing Measures, Second Edition (SPM™-2), a parent-report survey.Results indicate that 16 ASD children successfully completed the task, standing longer in tandem under NOISE compared to NORMAL, while all TD children achieved the maximum duration. CoP velocity decreased in NOISE for both groups, with significant differences in the low-frequency component between ASD and TD participants. Further analysis within the ASD group revealed that those with severe auditory difficulties exhibited reduced postural stability, particularly in the low-frequency component under NOISE. However, sensory challenges in other domains did not significantly impact postural stability.In sum, this research demonstrates the positive influence of appropriate auditory stimuli on postural control in children with ASD. While affirming the feasibility of the inclusive, community-centered approach, future studies should employ diverse conditions and larger sample sizes to elucidate underlying mechanisms. This exploration contributes to a deeper understanding of sensory-motor interactions in ASD, providing a foundation for potential therapeutic interventions.
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    Examining the Association Between Neighborhood Walkability and Cardiovascular Health in Texas and Bexar County
    (2023) Awadhesh Kumar, Anamika
    Built environment plays a significant role in improving cardiovascular health. Neighborhood walkability can be seen as an important determinant of increased physical activity, thus can confer against coronary heart disease and traditional risk factors- high BP, high cholesterol, diabetes, and obesity. This project investigates the relationship between neighborhood walkability and coronary artery disease (CAD) and its risk factors at the census tract level in Texas and Bexar County separately. Additionally, it explores the mediation impact of the related risk factors on the relationship between walkability and coronary artery disease. The CDC's Places dataset, which provides the prevalence of CAD and risk factors on census tracts level, is linked with the walkability index, calculated from the US Environmental Protection Agency data. The research demonstrates a relevant decrease in the prevalence of CAD and traditional risk factors across walkability quartiles in Texas. However, there is no significant stepwise decrease is found in the prevalence of cardiovascular disease and walkability index in Bexar County. The disparity in results of the two research areas can be attributed to a smaller number of census tracts and local factors of Bexar County. Because of inconsistent findings in the prevalence of cardiovascular health within walkability quartiles in San Antonio, the regression and mediation analysis are performed for only Texas.Moreover, Spearman's correlation tests confirm a significant negative relationship between the walkability index (WI) and CAD and its risk factors in Texas. Even after adjusting for various factors, a continuous walkability index remains significantly associated with a lower prevalence of CAD in Texas. Furthermore, the association between the walkability index and CAD appears to be partially mediated by the prevalence of high blood pressure, high cholesterol, diabetes, and obesity. Overall, the analysis indicates that neighborhood walkability is linked to reduced cardiovascular risk factors and CAD prevalence in Texas. Moreover, the prevalence of risk factors partially mediates the relationship between walkability and CAD.
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    Racial Disparities in Black-White Maternal Mortality in the United States
    (2023) Assogba, Albert Kofi
    This study examines the disparities in maternal mortality between Black and White women in the United States from 2015 to 2019. It explored the persistent Black-White disparities in maternal mortality, shedding light on the factors contributing to these disparities. Assessed the impact of Medicaid expansion under the Affordable Care Act (ACA) by analyzing maternal mortality rates in states that implemented Medicaid expansion at different time points across the United States and explored the relationship between maternal age at first birth, parity, and adverse pregnancy outcomes among Black and White women, providing insights into potential contributing factors to adverse pregnancy outcomes. Data from the US Mortality Data (2009-2019), Natality Data (National Center for Health Statistics (NCHS), 2009-2019), the American Community Survey (5-year Estimates, 2019), and Area Health Resources File (2015-2019) were analyzed. The findings indicated that communities with a greater proportion of Black residents tended to experience more hospital shutdowns for obstetric services. In contrast, states that broadened their Medicaid programs witnessed lower rates of maternal mortality and lack of insurance. Black women were discovered to be at an increased risk of unfavorable pregnancy outcomes compared to White women, irrespective of whether it was their first or second childbirth. The study infers that the expansion of Medicaid under the ACA has a direct impact on maternal health results. Nonetheless, a joint effort from healthcare providers, policymakers, researchers, and communities is crucial to eradicate racial inequalities in maternal health and guarantee equal chances for secure and healthy pregnancies.