UTSA Runner Research Press (Univ. of Texas at San Antonio)
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Physical activity and local blue/green space access during the COVID-19 pandemic
No full textPurpose: To examine whether local blue and green space access was associated with weekly physical activity frequency during the COVID-19 pandemic.
Design: Cross-sectional.
Setting: Population-based, nationally representative sample of U.S. adults (May and June 2021).
Sample: Adults, ages 18-94 (N = 1,771).
Measures: Self-reported data included the presence of blue spaces (e.g., lakes, outdoor swimming pools, riverside trails) and green spaces (e.g., parks, forests, or natural trails) in their neighborhoods, and days of physical activity per week (e.g., running, swimming, bicycling, lifting weights, playing sports, or doing yoga).
Analysis: Multiple Poisson regression assessed relationships between blue and green spaces and physical activity, with coefficients transformed into incidence risk ratios (IRR).
Results: Among participants, 67.2% reported living near a blue space and 86.1% reported living near a green space. Racial/ethnic and socioeconomic disparities in access to blue and green spaces were observed, with less access among non-Hispanic Black participants and those with lower income and educational attainment. Living near blue (IRR = 1.23, 95% CI = 1.10, 1.39) or green space (IRR = 1.25, 95% CI = 1.02, 1.54) was significantly associated with more frequent weekly physical activity.
Conclusion: Proximity to blue or green spaces is associated with more frequent physical activity during the COVID-19 pandemic. Health promotion efforts should include equitable strategies to improve accessibility to blue and green spaces.Social Wor
Apply Reinforcement Learning to Control Traffic Signals by Action Space Optimizations
No full textVehicle traffic systems can be improved by optimized traffic signal control. Performance metrics including accumulated waiting time and total fuel consumption are affected by different configurations of traffic signal controllers. This thesis describes a workflow for defining effective traffic signal controllers utilizing reinforcement learning. Configuration of components for reinforcement learning are explained, with a focus on phase set and action space definitions, to result in performance metrics improvement. A combinatorial search method where traffic signals were configured with different viable phase sets is presented, to identify individual phases of interest or concern. An improved phase set, now action space for the reinforcement learning agent(s), was then constructed composed of top performers from the combinatorial search. Analysis results show that reinforcement learning agents benefit from having an action space defined from highly ranked phases and learn to produce combined positive behaviors from different phase sets. At peak hours, morning, noon, and evening, of vehicle traffic simulation, optimized phase sets and action spaces produced a reduction in accumulated waiting time and fuel consumption.Electrical and Computer Engineerin
Los Efectos de la Alimentación Suplementaria en el Uso del Espacio de las Aves de Patio en San Antonio, Texas
No full textIn urban areas, supplementary food provided via bird feeders is abundant and aggregated, and thus may change the distribution of food. In so doing, bird feeders may act as hotspots of foraging behavior, allowing birds to reduce the time and area spent foraging. In this study, the effects of supplementary feeding on the space use of northern cardinals (Cardinalis cardinalis, hereafter cardinals) and northern mockingbirds (Mimus polyglottos, hereafter mockingbirds) were evaluated in the breeding season in San Antonio, Texas, United States, an urban, subtropical city. Specifically, in the Spring of 2023, 32 sites were initially and randomly allocated to a treatment of supplemented with bird feed (bird feeder) or not supplemented, and then switched halfway through a 42-day feeding experiment. The supplemented feed consisted of mixed seed and dried mealworms (Tenebrio molitor) and was provided by the residents in urban backyards. During the experiment, I used an automated radio-telemetry system to collect spatial movements of cardinals and mockingbirds relevant to supplemental feed to assess if hotspots of food affected foraging behavior compared to sites not supplemented. This study demonstrated that supplementary food did not have a significant effect on the space use of either species, but rather a tendency to affect the movements of cardinals. Despite the limitations of the study, including its short duration and small sample sizes, this research addressed existing knowledge gaps by providing new insights into the relationship between supplementary feeding and the space use of common backyard birds in urban areas.En áreas urbanas, la comida suplementaria proporcionada a través de comederos para aves es abundante y agregada, lo que puede alterar la distribución de alimentos. Al hacerlo, los comederos para aves pueden actuar como puntos críticos de comportamiento de forrajeo, permitiendo que las aves reduzcan el tiempo y el área dedicados a la búsqueda de alimento. En este estudio, se evaluaron los efectos de la alimentación suplementaria en el uso del espacio por parte de los cardenales rojos (Cardinalis cardinalis, en adelante cardenales) y los sinsontes norteños (Mimus polyglottos, en adelante sinsontes) durante la temporada de cría en San Antonio, Texas, Estados Unidos, una ciudad urbana y subtropical. Específicamente, en la primavera de 2023, 32 sitios fueron asignados inicialmente y al azar a un tratamiento de suplemento con comida para aves (comedero) o no suplementado, y luego se intercambiaron a la mitad de un experimento de alimentación de 42 días. La comida suplementaria consistió en una mezcla de semillas y gusanos de harina secos (Tenebrio molitor) y fue proporcionada por los residentes en patios urbanos. Durante el experimento, utilicé un sistema automatizado de radio-telemetría para recopilar los movimientos espaciales de cardenales y sinsontes en relación con la comida suplementaria para evaluar si los puntos críticos de alimento afectaron el comportamiento de forrajeo en comparación con los sitios no suplementados. Este estudio demostró que la comida suplementaria no tuvo un efecto significativo en el uso del espacio de ninguna de las especies, sino una tendencia a afectar los movimientos de los cardenales. A pesar de las limitaciones del estudio, incluidas su corta duración y tamaños de muestra pequeños, esta investigación abordó las brechas de conocimiento existentes al proporcionar nuevos conocimientos sobre la relación entre la alimentación suplementaria y el uso del espacio de las aves comunes de los patios traseros en áreas urbanas.Integrative Biolog
A Review of Research on Mathematics Teacher Educator Knowledge: Mapping the Terrain
No full textOver the past two decades, the landscape of research on mathematics teacher educators (MTEs) has grown considerably. One particular area of interest has focused on MTE knowledge and the ways in which it is developed and used in teaching practice. However, studies have conceptualized MTE knowledge in different ways and have employed considerably different methodologies and approaches to its study. In an effort to understand this varied landscape, we conducted an extensive review of research on the nature and development of MTE knowledge. This review provides a broad descriptive analysis of the existing theoretical and empirical research on MTEs' knowledge, explores the theoretical underpinnings of the existing frameworks for and studies on MTE knowledge, and considers implications for future research.Mathematic
Statistical and Spatial Analysis of Large Truck Crashes in Texas (2017–2021)
Get PDFFreight transportation, dominated by trucks, is an integral part of trade and production in the USA. Given the prevalence of large truck crashes, a comprehensive investigation is imperative to ascertain the underlying causes. This study analyzed 2017–2021 Texas crash data to identify factors impacting large truck crash rates and injury severity and to locate high-risk zones for severe incidents. Logistic regression models and bivariate analysis were utilized to assess the impacts of various crash-related variables individually and collectively. Heat maps and hotspot analysis were employed to pinpoint areas with a high frequency of both minor and severe large truck crashes. The findings of the investigation highlighted night-time no-passing zones and marked lanes as primary road traffic control, highway or FM roads, a higher posted road speed limit, dark lighting conditions, male and older drivers, and curved road alignment as prominent contributing factors to large truck crashes. Furthermore, in cases where the large truck driver was determined not to be at fault, the likelihood of severe collisions significantly increased. The study's findings urge policymakers to prioritize infrastructure improvements like dual left-turn lanes and extended exit ramps while advocating for wider adoption of safety technologies like lane departure warnings and autonomous emergency braking. Additionally, public awareness campaigns aimed at reducing distracted driving and drunk driving, particularly among truck drivers, could significantly reduce crashes. By implementing these targeted solutions, we can create safer roads for everyone in Texas.Civil and Environmental Engineering, and Construction Managemen
Pedagogizing Identity in Teacher Education Through Critical Autoethnographic Narrative
No full textIn this study, I report on my use of critical autoethnographic narrative (CAN) writing with English language teacher candidates (TCs) in a graduate-level teacher education course. In that iterative, scaffolded writing activity, I coached TCs to construct their teacher identity in narrative and make visible to themselves ideologies dominant in the sociopolitical context of language teaching. Drawing data from my CAN implementation in Spring 2023, I analyze Pamela’s (pseudonym) case to address this research question: How does she construct her English language teacher identity in a semester-long CAN writing activity? The qualitative data analysis demonstrates that Pamela’s language teacher identity involved: (a) becoming a social justice advocate, (b) grappling with neurodiversity, and (c) positioning language as an evolving local contextualized practice. Based on her positioning of language, she denies ‘one right way’ approach to language use, ‘teaching as correcting errors’ approach, and ‘assessment as gatekeeping’ approach as part of her teacher identity. Pamela’s CAN shows that the personal, professional, and political dimensions of language teaching are intricately intertwined in teacher identity, and that teacher identity construction involves tensions of competing ideologies in the sociopolitical context.Bicultural-Bilingual Studie
Atmospheric Pitting Corrosion of Austenitic Stainless Steel 316L Under Seawater and MgCl2 Solution Droplets
No full textThe full text of this item is not available at this time because the author has placed this item under an embargo until September 11, 2026.The maintenance and repair of the storage canister for spent nuclear fuel (SNF) are of importance to safely maintaining the national strategic fuel supply chain. End-of-life storage is an integral component of the infrastructure supporting the long-term viability of the existing U.S. reactor fleet. Stainless steels (SSs) are widely used as a structural material for nuclear power plants. In the dry storage of spent nuclear fuels within the concrete cask, SS canisters are used as an important barrier to separate SNF (radioactive material) and the environment. Due to the formation of protective passive film austenitic SSs have a wide spectrum of resistance to atmospheric corrosion. However, such passive film is susceptible to breakdown in the presence of chloride ions, resulting in pitting corrosion. In addition, the fabrication method of the canisters includes welding. If the material is not heat treated correctly, it can introduce a sensitized microstructure. In this research the initial stage of atmospheric corrosion of seawater and MgCl2 droplets on Austenitic SS316L was evaluated. The current research aims to understand the effect of droplet size, relative humidity (RH), sensitization, temperature, and salt type on the pitting corrosion of SS 316L in atmospheric environment under seawater and MgCl2 droplets. RH and temperature fluctuations tend to influence atmospheric pitting corrosion under natural exposure conditions. SS coupons loaded with seawater and MgCl2 droplets with the same chloride deposit density (CDD) and volume were subjected to 40 % and 85 %RH at room temperature (23 oC) and 50 oC exposures for 1 and 2 months. The effect of microstructure was investigated under atmospheric conditions. The result indicates that increase in temperature, droplet size and decrease in RH tends to decrease the pitting corrosion resistance. Moreover, the MgCl2 droplets showed more corrosive behavior than the seawater droplets. The environmental effect was also observed in pit morphology. The pitting resistance of unsensitized samples were compared with samples sensitized at 675 oC for 24 h and samples sensitized at 800 oC for 2 h. Microstructure characterization was analyzed using Scanning electron microscope (SEM) and elemental mapping was performed using SEM-EDS (energy dispersive spectroscopy). The degree of sensitization (DOS) was evaluated using double loop electrochemical potentiokinetic reactivation (DLEPR) test technique. Moreover, thermodynamic modeling was performed using ThermoCalc and JmatPro to predict the carbide content in the sensitized specimens. The samples sensitized at 675 oC for 24 h showed less resistance to pitting corrosion compared to other material conditions for both atmospheric pitting resistance test and electrochemical tests. The corrosion morphology at different RH, temperature, salt solutions and microstructural conditions were also investigated. Pitting corrosion resistance of these alloys was also evaluated, using cyclic polarization curves at room temperature (23 oC) and constant RH of 85%. For the evaluation of the corrosion mechanism, the pitting potential and re-passivation potential were determined under droplets. Moreover, cathodic polarization tests were conducted to investigate the cathodic kinetics for different salt solutions under atmospheric conditions. In addition, pitting resistance of new emergent materials, in this case 3D printed using selective laser melting (SLM) technique SS316 L and carbon nanotube reinforced SS 316L, was investigated. Carbon nanotube reinforced samples showed enhanced pitting resistance. The results from this work will provide knowledge, not currently existent in the literature for SS 316L (conventional and SLM) to inform the safe conditions to operate nuclear waste storages and predict their life-cycle under atmospheric conditions.Mechanical Engineerin
Adaptive Design and Inference for Step-Stress Accelerated Life Tests with Lifetimes from Exponential and Log-Location-Scale Families of Distributions
No full textThis dissertation focuses on the development of an adaptive design for step-stress accelerated life testing (ALT) to address the challenges posed by extended lifetimes of consumer products. The advancement in manufacturing has led to longer operational life spans, making it difficult to perform product life testing at normal operating conditions. Accelerated life testing mitigates this issue by subjecting units to higher stress levels to acquire lifetime information more quickly, which can then be used to estimate the product's lifetime under normal operation through extrapolation using a regression model.
However, testing units at higher stress levels presents technical difficulties. To overcome this challenge, an adaptive design of step-stress ALT is proposed in this work. The stress levels are determined sequentially based on information obtained from preceding steps. After each stress level, the model parameters are updated, and decisions regarding the next stress level are made using D-, C-, A-, E-, and M-optimality design criteria. The adaptive design and inference are illustrated using exponential lifetimes with progressive Type-I censoring for D- and C-optimality criteria, assuming a log-linear relationship between the mean lifetime and stress levels.
A comparative study is conducted between the adaptive step-stress ALT (ada-ssALT) and the simple step-stress ALT (ssALT) models. Numerical tuning of parameters is performed to reduce estimation bias and improve precision, along with determining confidence intervals using approximate and empirical approaches. Multiple design criteria, including D-, C-, A-, E-, and M- optimality criteria, are considered. Computational results demonstrate the superiority of ada-ssALT over ssALT. A real case study shows that the proposed algorithm outperforms ssALT in the presence of a shock effect.
Furthermore, the dissertation extends the adaptive step-stress ALT framework to incorporate a broader range of lifetime distributions. While the exponential distribution assumes a constant hazard function, a log-location-scale family enables the analysis of data with a shape parameter, providing flexibility. The generalized form of ada-ssALT is developed for lifetime distributions following a log-location-scale family at each stress level. This includes model formulation, maximum likelihood estimation, and derivation of the information matrix, assuming a linear relationship between the standardized stress level and the location parameter. A simulation study is conducted to compare the results of ada-ssALT with ssALT under various design criteria, including D, C, A, M, and E.Management Science and Statistic
Evolution Characteristics of Meteorological and Hydrological Drought in an Arid Oasis of Northwest China
No full textIn the context of global warming, the acceleration of the water cycle increases the risk of meteorological drought (MD) and hydrological drought (HD) in the arid region of Northwest China. The Manas River Basin is a typical agricultural oasis and the largest oasis farming area in Xinjiang, Northwest China. Droughts in this basin have significant implications for both agricultural production and the livelihoods of inhabitants. To evaluate the MD and HD and provide information for drought relief in the MRB, the standardized precipitation evapotranspiration index (SPEI) and standardized runoff index (SRI) were calculated using long-term rainfall and runoff data. Subsequently, combined with ArcGIS 10.3 software and the trend analysis method, the SPEI and SRI characteristics were evaluated at different time scales (1-, 3-, 6-, and 12-month). There were three main findings. First, both MD and HD were alleviated, with significantly more HD alleviation. MDs in spring and autumn exhibited a trend of aggravation. The SRIs in summer, autumn, and winter increased significantly at a confidence level of <i>p</i> &lt; 0.01, with an insignificant decline in spring. In the 2010s, the frequency of light drought of MD was stable at 10% to 20%, while severe and extreme droughts increased. The frequency of HDs has decreased since the 1990s. Second, on annual and seasonal scales, MDs occurred mainly as light and moderate droughts. The highest frequency of MD was 24% of moderate droughts in winter. Spatially, the northern region of the MRB was characterized by more frequent light and extreme droughts. Third, runoff in the Manas River Basin increased significantly during the 1990s, which may have been related to the acceleration of glacial retreat in the Tianshan Mountains. This study can effectively reveal the changes in meteorological and hydrological drought in NWC and provide the basis for risk decision-making and management for watershed managers.Earth and Planetary Science
From Pure to Puro: The Racialization of Space Within San Antonio's South Side
No full textThis thesis illuminates the history of San Antonio's South Side. While there is abundant literature on the area during San Antonio's colonial period, the South Side's twentieth century story is overlooked in the city's historical narrative. This absence from the historiography needs to be remedied because the South Side's history provides further understanding to the methods of indigenous displacement, the institutionalization of white supremacy, community formation, the methods of organization, and the reasons for grassroots activism.
During the mid- to late-nineteenth century, Anglo businessmen gained control of the former mission lands south of San Antonio's urban core. Their utilization of discriminatory practices led to the area's Anglicization. However, by the 1950s, ethnic Mexicans began to move into the South Side. Their newfound sense of socioeconomic mobility led to them challenging the area's longheld racial power structure. The Mexican-American presence in the South Side catalyzed former Anglo residents to move north, taking with them theirs and the city administration's financial and material resources. This resource reallocation led to the area's physical decline. The resultant infrastructural instabilities soon defined the South Side's colloquial identity. But, the ethnic Mexican residents did not let it define their self identities and notions of community. Their responses to the instabilities demonstrates not only their commitment to communal advancement, but also how deeply engrained white supremacy is within the city's foundation.Histor