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.
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Item A Case Study of a Dual Language School: Principal and Teacher Perspectives(2018) Ponce, Gilberto MartinThe purpose of this qualitative case study is to investigate the characteristics of a sustained dual language campus as well as the contributions made by the schools building principal. The exploration of the principals driving emphasis in the school may give insight into how to continue to sustain a progressive dual language program, and the understandings a principal must have when leading a dual language school. In-depth interviews were conducted to collect data from various teachers of at least five years of experience at the dual language campus as well as the building principal of said campus. A total of six teachers and one principal were interviewed once individually, then the teachers were broken into two focus groups of three members. The questions for the interviews were framed under a culturally relevant pedagogy model, then the responses were analyzed to form a new model of sustainability. The results of this study indicate that building principals must critically reflect on some cultural aspects of the school, specifically: a reflection of cultural consciousness, a belief that dual language education is an equitable practice, and advocacy for students and high achievement are necessary. Leaders of dual language campus' must validate the student's cultural wealth; this includes their role in the school, community, home and how language plays an important role in the functioning of the sustainability. Finally, principals should understand that the process of reflection and re-evaluation is constant and should continue as such.Item A Case Study of Leadership Practices in a Dual Language Program(2024) Almanza, OliviaThe purpose of this qualitative study was to investigate the perception of the principal and teachers regarding what transformational leadership practices meet the needs of EBs in a DLI PK-8th grade campus in South Texas. The research site was selected for having 40% emergent bilingual students. The campus principal has been implementing a comprehensive 80:20 dual language immersion program for more than five years, and the campus has received an “A†rating from the Texas Education Agency based on State of Texas Assessment of Academic Readiness (STAAR) assessments more than once. Data were collected from the research site by utilizing Seidman (2006) interview series which consist of three rounds of structured interviews from the principal, two interviews from two bilingual teachers, and one from the focus group which consisted of three bilingual teachers. Following Saldaña’s (2021) coding process, the data were collected, categorized, and given a code aligned to the transformational leadership theory. The main themes that emerged on the leadership practices used to implement a comprehensive dual language program in a PK-8th grade campus are the following: (1) Build a Shared Vision through Stakeholder Involvement; (2) Model School Practices and Advocate; (3) Build relationships, Empower, and Distribute Leadership; (4) Facilitate Teacher Reflection for Student and School Improvement. The findings indicate that the principal set structures to transform a traditional school to a dual language immersion campus. He engaged stakeholders in building the vision of the school and modeled practices that he expected his staff to emulate. One of the core leadership practices that he implemented was collaboration and used it to engage staff in working as a team as they met and discussed school progress. He built positive relationships with staff, students, and families. He inspired his subordinates to explore new approaches, empowered them, and increased capacity. He also created space for students to meet with him so they could express campus improvements that needed to be made based on their lens. Transformational leadership practices have had a positive effect in a dual language campus in obtaining high levels of performance of teachers which ensured high academic achievement of students.Item A Comparison of Dayside Magnetopause Reconnection at the Rotationally Driven Magnetosphere of Saturn and the Solar Wind Driven Magnetosphere of the Earth(2021) Sawyer, Rhyan PatricThis dissertation focuses on the study of various aspects of magnetic reconnection, including factors that may influence this phenomenon such as suppressing onset, as well as the response of the plasma environment as a result of magnetic reconnection. The first part of the dissertation explores magnetic reconnection at the rotationally driven magnetosphere of Saturn. By using signatures of heated electron flows and a maximum magnetic shear model, it was possible to determine if reconnection was occurring and where the reconnection site was at Saturn's magnetopause. Results are presented of several reconnection events at the magnetopause of Saturn. The next part presents the calibration of two ion electrostatic analyzers that were carried on the Twin Rocket to Investigate Cusp Electrodynamics 2 sounding rockets. These ion instruments were utilized to explore magnetic reconnection by measuring ion plasma distributions at the Earth's low altitude northern magnetospheric cusp. Utilizing the calibrated ion instruments, the next part presents two studies of ion dynamics within the cusp. The first study presents evidence that warm plasma cloak material was present at low altitudes on cusp field lines. These results suggest warm plasma cloak material was able to precipitate to low altitudes on an open flux tube. The second study presents evidence of a convecting ionospheric upflowing conic distribution within the cusp at low altitudes. These results allow for the determination of the convection velocity using low energy ion distributions. This dissertation presents an ensemble of various aspects of magnetic reconnection, pushing our knowledge ever forward.Item A comparison of different methods for calculating tangent-stifess matrices in a massively parallel computational peridynamics code(2013) Brothers, Michael D.In order to maintain the quadratic convergence properties of the first-order Newton's method in quasi-static nonlinear analysis of solid structures it is crucial to obtain accurate, algorithmically consistent tangent-stiffness matrices. For an extremely small class of nonlinear material models, these consistent tangent-stiffness operators can be derived analytically; however, most often in practice, they are found through numerical approximation of derivatives. A goal of the study described in this thesis was to establish the suitability of an under-explored method for computing tangent-stiffness operators, referred to here as 'complex-step'. Compared are four methods of numerical derivative calculation: automatic differentiation, complex-step, forward finite difference, and central finite difference in the context of tangent-stiffness matrix calculation in a massively parallel computational peridynamics code. The complex-step method was newly implemented in the peridynamics code for the purpose of this comparison. The methods were compared through in situ profiling of the code for Jacobian accuracy, solution accuracy, speed, efficiency, Newton's method convergence rate and parallel scalability. The performance data was intended to serve as practical guide for code developers and analysts faced with choosing which method best suit the needs of their application code. The results indicated that complex-step produces Jacobians very similar, as measured by a low l 2 norm of element wise difference, to automatic differentiation. The values for this accuracy metric computed for forward finite difference and central finite difference indicated orders of magnitude worse Jacobian accuracy than complex-step, but convergence vstudy results showed that convergence rate and solution was not strongly affected. Ultimately it was speculated that further studies on the effect of Jacobian accuracy may better accompany experiments conducted on plastic material models or towards the evaluation of approximate and Quasi-Newton's methodsItem A complex finite element method to compute accurate weight functions(2012) Wagner, DavidAnalytically extending the finite element method to the complex domain provides a means to determine accurately the weight function of a crack in a twodimensional object of any specific shape. When the imaginary part of a two dimensional finite element model's nodal coordinates represents a small opening mode increase of a modeled crack's length, the openingmode weight function for that crack may be determined directly from the solution's complex displacements and complex strain energy calculation. The accuracy of this novel method is limited only by the fidelity of the finite element mesh used to model the object.Item A Comprehensive Quantitative Evaluation of Rotator Cuff Muscle Properties Using Novel Imaging Techniques and Muscle Regenerative Therapeutics(2023) Treviño, Jose Hernandez, IIIThe current course of treatment for rotator cuff tears depends on numerous factors, such as tear size, intramuscular fatty infiltration, metabolic diseases, muscular atrophy, age, and muscle stiffness. These multiple factors affecting muscles and tendons are evaluated in the clinical setting via various diagnostics imaging tools and physical manipulations of the shoulder. However, current clinical methods present several limitations that prevent a comprehensive, quantitative, and accurate estimation of muscle properties and rotator cuff tear prognosis. As a result, treatment for such defects that have failed conservative management depends solely on surgical techniques. Thus, novel non-invasive imaging approaches that quantify muscle properties should be developed to aid clinicians during surgical planning and implementation of rehabilitation protocols. Furthermore, novel therapeutics should be designed to improve muscle quality and reduce the high rates of repair failures. For this purpose, the goal of the current study was twofold: first, to develop imaging approaches to quantify the properties of the rotator cuff muscles to improve diagnosis and rehabilitation management; second, to investigate the feasibility of novel therapeutics that can be used for muscle regeneration. The objectives of the current study were to quantify the degenerative properties (i.e., volumetric intramuscular fatty infiltration, atrophy, and stiffness) using magnetic resonance imaging (MRI) and ultrasound shear wave elastography (SWE) imaging of the rotator cuff muscles and to determine the response of skeletal muscle precursor cells when exposed to therapeutics involved in age-associated cell dysfunction. We have developed the following aims to reach our goal and objective: Specific Aim 1: Quantify the volumetric distribution of degenerative properties in the supraspinatus muscle using novel magnetic resonance imaging techniques. Specific Aim 2: Determine the role and activity of the individual sub-regions of the infraspinatus muscle and teres minor muscle using ultrasound shear wave elastography during external shoulder rotation. Specific Aim 3: Evaluate the effect of novel therapeutic interventions on muscle regenerative properties. Successful outcomes from this study will allow for a more comprehensive and quantitative evaluation of skeletal muscles and pave the way for developing novel therapeutics that can restore muscle function, eventually reducing the high incidence of repair re-tears.Item A Conceptual Model for Environmental Sustainability: A Case Study of Two Small Counties in the Texas Eagle Ford Shale Region(2017) Adeoye, Oyinkansola OlamideEnvironmental sustainability is an extension of the concept of sustainability that focuses on the importance of understanding the interconnectivity between natural and socio-economic systems without compromising resource capacity. In this study, it is incorporated into a framework that applies to the sustainable development of small counties in the South Texas region of the Eagle Ford Shale. The research involved a qualitative approach through the distribution of a questionnaire to a surveyed sample of Texas residents from Gonzales and Karnes counties. The purpose of the questionnaire was to obtain the expressed perspectives of residents regarding the impacts of shale development on their quality of life. These locations of interest were selected because of the different levels of shale development they experienced. Aspects of quality of life were analyzed as indicators of the survey responses to open and closed-ended questions. Participants described and scaled variables regarding impacts, benefits, and notable changes they experienced from the development of shale resources in their counties. Content analysis was used to obtain results relevant to developing the conceptual model for environmental sustainability proposed in this study. Findings showed that the sample of participating residents highly identified with socio-economic interests compared to environmental interests, considering that when the study was conducted shale oil and gas production was in decline as a result of fallen global energy prices. In this study the terms sustainability and sustainable development were used interchangeably, while development was addressed in a broad sense, referring to the overall improvement of quality of life.Item A Consequential Validity Study of a State English Language Proficiency Assessment: The Texas English Language Assessment Program (TELPAS)(2021) Collier, Jo-KateWith this study I investigate the consequential validity of a state English language proficiency (ELP) assessment, following Messick's (1989) expanded theory on validity. I examined intended and unintended consequences of the Texas English Language Proficiency Assessment System (TELPAS) through stakeholder perceptions. TELPAS is a federally required annual assessment used to measure the English proficiency of English learner (EL) students enrolled in public schools in Texas. TELPAS is a high-stakes test impacting over a million EL students and their campuses and districts (Texas Education Agency [TEA], 2020). In 2019-20, Texas planned for increased stakes regarding TELPAS as its role within state and federal accountability systems became more impactful due to implementation of new federal requirements under the Every Student Succeeds Act (ESSA, 2015). The law requires that states embed results from state ELP testing within state accountability systems (ESSA, 2015) eliminating multiple systems of accountability but increasing the stakes for ELP testing by giving it a higher profile. Research advocating more robust validity studies of ELP assessment instruments is needed (Chalhoub-Deville, 2020). With this study I contribute to such a body of research by conducting a mixed methods investigation, using survey research and semi-structured interviews, of aspects of the consequential validity of TELPAS. I explore key stakeholders' perceptions of the intended and unintended consequences of TELPAS.Item A critical analysis of Nikolaus Pevsner's theory of the origin of the Modern Movement(2013) Carroll, Michael PatrickWith Pioneers of the Modern Movement, Nikolaus Pevsner evoked a controversy which has survived for over three quarters of a century. Following years of acerbic condemnation, it is generally accepted that Pevsner's theory tracing the origin of the Modern Movement to William Morris and Walter Gropius has been discredited. I believe that the critics' own stylistic biases, combined with Pevsner's provocative polemics, have obscured the value of a theory designed to reveal the genesis of a narrowly-defined movement in architecture. The conclusions within this thesis follow an extensive review of the works of authors who are critical of Pioneers, research of literature relating to factors influential to the evolution of the Modern Movement in Germany, and an in-depth study of Pioneers itself. Those who extrapolate Pevsner's theory in an attempt to suggest that it is meant as an explanation for the source of the broader phenomenon of modern architecture do a disservice to this work. As a complete history of modern architecture, Pioneers is limited in scope. Contrary to being a detriment, this brevity makes it an excellent source for introducing a discourse on modern architecture to the fledgling theorist.Item A critical examination of language ideologies and identities of Cambodian foreign-trained university lecturers of English(2014) Boun, SovichethThe global spread of English has resulted in differing views among scholars who attributed it, on the one hand, to choices made by national actors for political and economic integration and, on the other hand, to linguistic imperialism from first-world English-speaking countries. In Cambodia, despite its momentum, the spread of English and English language teaching (ELT) has not been critically examined. More research is needed that examines the sociological and political aspects of English and ELT in Cambodia. As Pennycook (1994) maintained, the spread of English and ELT is imbued with cultural, economic, political and ideological meanings, irreducible to the examination of its functionalist roles as natural, neutral and beneficial. Drawing on language ideology and community of practice perspectives, this study explores the interrelations among language ideologies, classroom practices and the negotiation of identities. Data collected in the Spring of 2013 in Cambodia include interviews with university lecturers who received their master's degrees in ELT-related fields abroad, classroom observations, social observations, and relevant documents and artifacts. The findings reveal four ideological categories around which the participants expressed a range of ideological views about English and English language teaching: (1) image and status of English; (2) image and status of Khmer; (3) native speakers vs. non-native speakers; and (4) English language teaching. These various ideologies have been attributed to four sociocultural contexts of their experiences which include personal observations/experiences, prior learning/education, teaching experiences, and educational experiences abroad. The findings also indicate how these ideologies contribute to the participants' negotiation of teaching practices and formation of identities. This study adds to the current understanding of the global spread of English, the native speaker ideology, the communicative language teaching, and the transnationalization of TESOL education.Item A Detailed Monte Carlo and Measurement-Based Assessment of Gold Nanoparticle Dose Enhancement for Ir-192 HDR Brachytherapy, External Beam Radiation Therapy and Image Contrast Enhancement for Computed Tomography (CT) and Cone Beam CT(2020) Gray, TaraRadiation therapy has long been one of oncologists' most effective weapons to combat cancer. Advances in beam shaping and imaging-guided approaches have paved the way towards more effective forms of radiation therapy with fewer side effects experienced by cancer patients. However, innovative strategies which can localize the effects of ionizing radiation while minimizing damage to surrounding tissue by lowering the overall dosage are still needed. One promising strategy is the use of targeted gold nanoparticles to locally enhance radiation while also providing image contrast enhancement. The ultimate goal of this research project was to develop an optimized nanoparticle-based method for image enhancement and radiation sensitization. In order to accomplish this goal, four specific aims were pursued: (1) Computationally-aided design to predict and interpret the dose enhancing effects of gold nanoparticles both on the macroscopic and microscopic scale using accurate x-ray and radioactive source geometry with different sizes, concentrations and shapes of gold nanoparticles, (2) Experimental synthesis of different sizes and concentrations of radiation-enhancing gold nanoparticles and developing optimal experimental dose enhancement and image contrast enhancement measurement set-ups guided by Monte Carlo simulations, (3) Experimental characterization of the local radiation dose enhancement and image contrast enhancing effects due to different sizes and concentrations of gold nanoparticles, and (4) Experimental in vitro investigation of the radiobiological effects of gold nanoparticles. Three novel aspects of this project also distinguish it from previous studies of nanoparticle-enhanced radiation therapy. First, the theoretical gold nanoparticle dose enhancement at different therapeutic radiation therapy energies staring with Ir-192 and going up to 18 MV energy and for different imaging modalities (Computed Tomography and Cone Beam Computed Tomography), was rationally guided by Monte Carlo computer simulations, involving accurate radiation beam and radiation source set-ups, to determine the optimum nanoparticle size, concentration and surface area to volume ratio (on the nanometer scale) that maximizes X-ray interactions at these energy ranges both macroscopically and microscopically. Second, these simulations were utilized to guide the optimal gold nanoparticle (GNP) size and concentration to produce optimal dose enhancement experimentally and guide the experimental set-up for experiments involving both imaging and therapy enhancement, with the long-term goal of developing theranostic applications. Thirdly, in vitro cell studies were performed by irradiating C-33a cervical cancer cells, dosed with different concentrations of GNPs, with 18 MV energy to observe the enhanced radiobiological cell killing effects of GNPs with different doses of high energy radiation using a Trypan Blue assay. The key areas of focus of this project are medical physics and radiation oncology, and the secondary areas of focus are imaging and biomedical engineering.Item A discourse analysis of U.S. national and state language policies: restraining English instruction for refugee adults(2012) Whitney, Diana Maria JosephinaUsing a (critical) discourse analytic approach, this thesis examines how refugee policies at different scales (state and national) interact and entextualize specific perspectives on second language acquisition. Policy texts examined include the Refugee Act (1980), Code of Federal Regulations (2011), Texas Administrative Code (2004), Request for Proposals (RFP) for Refugee Social Services (2008), and the Refugee Social Services Provider Manual (2008). This study contrasts discourses of language acquisition and learning as reflected in policy documents with principles of second language learning to determine how these texts support or do not support long-term goals for English language development, integration, and self-sufficiency. The data show how discourses embedded in policies frame English as a Second Language (ESL) programs as an employability service with a principal focus on the achievement of economic self-sufficiency. Moreover, the discourses in the current policies, I show, have significant pedagogical implications, particularly in the allocation of federal funding for educational programs.Item A Finite Element-based Adaptive Energy Response Function Method for Curvilinear Progressive Fracture(2018) Wagner, DavidAn adaptive arbitrary-order curvilinear progressive 2D crack growth algorithm is presented. The method uses the ZFEM hypercomplex finite element program to compute arbitrary order derivatives of strain energy with respect to self-similar or perpendicular crack extensions, and then constructs a family of Taylor series functions of strain energy versus crack growth direction. An adaptive algorithm automatically selects the best high-degree polynomial to extrapolate a curvilinear crack path, and adjusts the length of the crack growth increment added during each simulation step to maintain the crack path and model energy within desired tolerances. The method is automated such that the full crack path from inception to failure is computed with multiple FE analyses. Numerical examples up to fifth order are presented and compared against experiments.Item A Grounded Theory Study of the Re-Entry Process of Teen Parents' Return to School After Dropping Out(2013) Melton, Brenda LeeWithout the rich stories of the experiences of teen parents who drop out of school and then re-enter, we do not have a total picture of the dropout phenomenon and how best to address the issues for this marginalized group. Using the research strategies of Charmaz' social constructivist grounded theory, Melton has gathered detailed stories about overcoming obstacles, connecting with others, and finding resources to complete their high school education. The pivotal role of school counselors as advocates becomes even more imperative to support teen parents in completing their education. Hopefully, this research has added depth to the understanding of what works, what is needed, and what interventions are most effective with teen parents. By using the Relational-Cultural Theoretical lens, Melton has developed the Model of Relational Resilience and Marginalization of Teen Parents who Re-enter High School after Dropping Out to better understand of the experiences of teen parents by defining their needs, exploring their resiliency, and highlighting the importance of protective factors and relationships in returning students to school.Item A Longitudinal Analysis of Adolescent Substance Use, Adverse Childhood Experiences, and Health Lifestyle Towards the Development of Substance Use Disorder Outcomes Among Young Women in the United States(2023) Sharmin, SarahWomen's substance use disorder is a critical public health problem, as its adverse impact extends beyond the individual to intergenerational and national levels. This study aimed to determine the association between early substance use during adolescence, adverse childhood experiences, and a healthy lifestyle with the development of substance use disorders in emerging and young adulthood. This study utilized data from the nationally representative National Longitudinal Study of Adolescent to Adulthood (Add Health) dataset. Three statistical techniques were employed: binary logistic regression, latent class analysis, and discrete-time analysis. The logistic regression models found that adolescents' early substance use (OR=1.62, CI: 1.29-2.03) and adverse childhood experiences (OR=1.34, 1.09-1.64) were significantly associated with the development of substance use disorders in emerging adulthood (ages 18-26) among women. Subsequently, latent class analysis was utilized to create a latent adolescent health lifestyle class to understand its association with the development of substance use disorders in young adulthood. A discrete-time analysis technique was applied to examine the transition to substance use disorders among women from adolescence to young adulthood. Adolescents (ages 12-17) with unhealthy lifestyles, substance use, and adverse childhood experiences exhibited a higher hazard ratio (HR=2.19, CI: 1.69-2.83) for transitioning to substance use disorders compared to those with protective lifestyles and no substance use or adverse experiences in young adulthood (ages 27-32). The present study significantly contributes to the understanding of the trajectory of substance use disorder development in women from adolescence to young adulthood.Item A mother that protects you: Community performance, identity, and values within the contrade and Palio di Siena(2016) Reid, Jessica MarieIn this thesis, the Palio horse race and the contrade (neighborhood) structure of Siena Italy are examined. Using thick description and grounded theory, ideas of residency, age, and identity construction are investigated among the contradaioli of Siena. It is of interest to see how these factors affect identity performativity on an individual and societal level. The value and increasing role of contradaioli women will also be discussed, as it is a topic that contradicts initial perceptions of women as a suppressed group. Although residency status within the contrada was previously known as the focal point of identity, over time its significance has shifted to account for a modern world with increased population mobilization. Residency patterns found to exist in Siena are reflected in the type and level of labor contributions made based on how far they lived from their contrada. Despite the initial perception that gender was the main factor that impacted participation and labor contributions, it was revealed that it was not the only significant variable and, in fact, age and residency was a more prominent dynamic to consider.Item A Multiple Case Study of Culturally Responsive Women Leaders in Southwest Texas Elementary Schools(2022) Castillo, Cynthia AnnThis study sought to extend the knowledge of the real-world application of leadership practices relevant and responsive to commonly marginalized students. This study focused on leadership practices of school leaders including principals and assistant principals through the lens of the theoretical framework crafted by Muhammad Khalifa (2018) titled Culturally Responsive School Leadership. This research provides a different perspective of school leadership and could help inform school administrators and district leaders regarding ways to implement leadership practices that would serve the specific needs of school communities. This study also identified the challenges that are faced in the efforts of serving as a culturally responsive school leader. The research design is a multiple case study (Merriam, 1998) model, in which two principals and one assistant principal took part in a three-interview series, discussing their personal and professional experiences with regard to education from their K-12 experiences through their school leader experiences. Two themes emerged from this study, including sense of belonging and serving the needs of the school community. Through these themes the findings suggest that school leaders in Southwest Texas employ Culturally Responsive School Leadership (Khalifa, 2018) by creating inclusive environments for their students and families, and by rejecting exclusionary practices. Different life experiences influenced all three school leaders as they do the work to lead schools with a majority of students of color. Common influences found across all three participants include the impact of their own cultural and socio-economic backgrounds from their upbringings, as well as experiences, good and bad, in the education system. Prospective school principals and assistant principals may benefit from this knowledge as they develop their own leadership style in preparation for the role of school leader. As higher education practitioners work to prepare prospective school leaders, the dissemination of non-traditional, community-based school leadership practices could be included in graduate coursework. Finally, this study could also contribute to the small but growing body of literature regarding Culturally Responsive School Leadership (Khalifa, 2018).Item A Narrative Case Study Situating Funds of Knowledge for Teaching Mathematics in the Lives of Three Latina Mother-Prospective Elementary Teachers(2022) Elmore, Traci LeThe purpose of this study is to explore how to raise awareness of, validate, and value the diverse knowledge bases that mother-prospective teachers have based in their prior experiences from within their families and backgrounds. Using a funds of knowledge (FoK) for teaching mathematics (Aguirre et al. 2012; Civil, 2007; Foote, 2009; González, et al., 2005) theoretical lens, this cross-cases study situates and interprets the narrative accounts of three Latina mothers and prospective teachers (PTs) as they reflect across their teacher preparation program experiences at a Hispanic-Serving Institution in the southwestern United States. As such, the study investigates 1) how Latina mother-PTs interpret utilizing children’s home and community FoK, especially for teaching mathematics, across their elementary teacher preparation program; and 2) the personal strengths and experiences Latina mother-PTs draw upon to inform their thinking about utilizing learner FoK for teaching mathematics. Results show that FoK is understood as the background knowledge and smartness from prior experiences outside of school that all learners possess. Further, students’ FoK should be used explicitly in instruction and are best uncovered through authentic relationships of care and trust with students and their families. Influenced by their mothers and grandmothers, Latina mother-PTs discuss leveraging educational and experience-based knowledge to help others succeed in the US school system. Implications for mathematics teacher educators include valuing and validating the familial and linguistic strengths that PTs from nondominant backgrounds bring with them to learning and teaching mathematics especially in their roles as significant adults in the lives of children.Item A Phenomenological Study of the Lived Wellness Experiences of Student Counselors in Practicum and Internship Who Are Concurrently Employed as Human Health Service Workers(2019) Dixon, Hannah CorneliusBurnout is prevalent among the helping professions. Professional counseling ethics direct counselors to practice and maintain wellness and self-care in an effort to avoid burnout and impairment. In addition, student counselors who maintain employment are at a higher risk of burnout. The current study explored the lived wellness experiences of student counselors in practicum or internship whom are concurrently employed as human health service workers. Eleven participants submitted demographic data and completed a semi-structured interview. I qualitatively analyzed the data using the transcendental phenomenological approach (Moustakas, 1994). The analysis derived eight themes and six subthemes. Primary thematic findings include burnout/role strain, compromise, the self-care hypocrisy, active self-care, mentorship, and mutual benefit of dual roles. Implications for student counselors and counselor preparation are provided. Limitations of the study and recommendations for future research are suggested.Item A PHREEQC Model of the Geochemical Variation across a Freshwater and Saline Water Interface, Edwards Balcones Fault-Zone Aquifer, South-Central Texas(2019) Webster, PhilipIn south central Texas, an area of brackish-water has been proposed to have developed by mixing in a zone of convergent flow of freshwater from the Edwards Balcones Fault-Zone aquifer and saline water from further downdip in the Edwards Group. To test the hypothesis, results of a geochemical model, developed using PHREEQC, are statistically analyzed and compared to analyses of chemical composition from monitoring wells along a transect from freshwater to saline water. Modeling geochemical variation across the interface can be used to explore mixing effects between freshwater and saline water and help highlight areas in the conceptual model that need further research. Simulation results are compared to monitoring wells to assess error, but the model is not calibrated in the traditional sense, rather all parameter combinations are simulated to establish a best-fit. The model included mixing of multiple water end-members and reactions between groundwater, calcite, dolomite, and gypsum. Water-mineral reactions were constrained by target saturation index of the minerals. Each parameter was assigned a range and interval. Simulations with different end-member combinations yielded different trends in total dissolved concentration (TDS) and ionic ratios across the simulated brackish-water zone, whereas changing percent contribution of end-members affected variability around the trends. Best-fit lines of the geochemical trends are calculated to compare different trends. Overall, geochemical trends across the simulation target saturation index values had the most significance. Mixing of freshwater and saline water causes an oversaturation with respect to calcite and, in most simulations, undersaturation to dolomite. The latter environment favors dedolomitization. Simulated supersaturation of groundwater with respect to calcite was controlled by changes in activity coefficients of calcite (Ca2+) and carbonate (CO32--) ions between the freshwater and saline end members. The extent of the simulated mixing zone that is undersaturated with respect to dolomite is dependent on the PCO2 of the saline endmember. Dolomite is undersaturated throughout the whole simulated mixing zone when using the most representative PCO2; as PCO2 decreases, the dolomite saturation curve increases causing parts of the simulated mixing zone to be oversaturated.