Digital Commons Network^™

Design And Testing Of A Modular Laser System With Laser Machining And Bioprinting Capabilities, Jesus Gonzalez

Theses and Dissertations

This thesis introduces the applications of ultrafast lasers while focusing on their bioprinting capabilities. A custom system was designed to utilize a femtosecond laser for 2D and 3D applications. The characteristics of lasers allow them to be efficiently used in machining, 3D printing, research, and more. Their power and precision allow them to be used for delicate work such as bioprinting. Bioprinting is a field holding great potential to benefit society. Studies conducted over the years prove its usefulness in printing cells and biomaterials, while showing there is still much to improve upon before being able to print fully functioning …

Constructing Associative Rings From Certain Hypergroups, Oscar Gonzalez

Theses and Dissertations

Tight hypergroups give rise to associative rings if the so-called general normality condition holds\cite{ARTICLE:1}. We consider four examples of tight hypergroups which do not satisfy the general normality condition and show that they still give rise to associative rings. Our examples are HM332(24),HM10353(32), HM10933(32) and HM10941(32)[1].

Educator Perspectives Of High-Stakes Testing In An Urban School District In Deep South Texas, Sergio R. Garcia

Theses and Dissertations

The purpose of this study was to explore how the high-stakes testing setting and the state assessments have influenced elementary teachers and other school professionals’ approach to preparing students for standardized tests. Policymakers and the public see standardized tests as simple quantifiable measures of school quality and student learning. They assume that high stakes tests will influence teachers and students to try harder and that the results will be used rationally to benefit all students.

Fredrick Herzberg’s Motivation-Hygiene Theory was used as a framework for this research. Study participants included nine experienced elementary school educators in a large urban district …

The Digital Reading Experiences Of Middle School Readers: A Phenomenological Study, Laura A. Hayward

Theses and Dissertations

Reading digitally is part of the 21st century New Literacies, residing in the curriculum as a comprehension skill developed with print reading skills. Differences exist between purpose of digital reading and print reading, manifested in the association of digital reading as a mostly non-fiction genre, the immediacy to digital information and its relevance to a reader’s decision about the usefulness of the information. Contrastingly, print reading can be fiction or non-fiction with access to all the text. The differences suggest that learning focused on immediate evaluation, synthesis, and application of information while reading digitally should be taught in the context …

Histological Evidence Of Annual And Lunar Reproductive Rhythms Of Atlantic Sea Urchin, Arbacia Punctulata In The Gulf Of Mexico: Changes In Nutritive Phagocytes In Relation To Gametogenesis, Eleazar Hernandez Ii

Theses and Dissertations

Environmental phenomena such as temperature, photoperiod, tidal cycle, and lunar rhythm act as external cues that stimulate the reproductive activity of marine organisms. In this study, I report the annual and lunar reproductive cycles, and changes in nutritive phagocytes (NPs) in relation to gonadal maturation of Atlantic sea urchin (Arbacia punctulata, a primeval species). Monthly and weekly changes in gonadal development/maturation were observed histologically. In male, the testicular lobules were densely packed with sperm from June to August. In female, on the other hand, mature eggs first appeared in some ovaries in May, numerically increased from June to …

Non-Space: The Perception Of Reality, Carlos Limas

Theses and Dissertations

This is a formal study of real-world images that try to convey a clear approach to the way we look and relate to unexpected places that at first glance don’t exist in a metaphorical way or just don’t strike us as interesting or attractive. There’s no particular story to tell only the need to expose a different kind of beauty through my own personal subjective view and sensitivity expanding the criteria of my own esthetic values and context of a captured image in a particular scenario.

The perception of Non-Space relates directly to a well establish photography technique called Deadpan, …

The Acute Effects Of Warm-Up With And Without Blood Flow Restriction Cuffs On Lower Body Temperature, Flexibility, And Vertical Jump Power, Phillipe Thomas Lopez

Theses and Dissertations

Purpose: The purpose of this study was to determine the effect of blood flow restriction warmups (BFR-WU) on skin temperature (ST), range of motion (ROM), and vertical jump (VJ) performance.

Methods: Forty-seven participants performed WU’s with unilateral BFR application. Each participant took part in five different WU durations. Measurements of ST, ROM, VJ were taken at baseline, post-WU, and post-8min.

Results: Significant conditions main effect (p<0.05), condition*time (p<0.05), WUduration*condition (p<0.01), and conditions*time*sex interactions (p<0.05) were found by repeated measures ANOVA.

Conclusion: The current findings reveal that BFR-WU’s react differently throughout time, when compared to NBFR-WU, for ST and VJ performance, but not ROM. The length of duration was only significant …

Shattering Taciturnity: The Use Of Visual Arts As A Method Of Communication And Expression, Jesmil M. Maldonado Rodriguez

Theses and Dissertations

Silence an action that conceals a person’s memories, thoughts, emotions, fears, and insecurities, making them crave a method of expression. In this case, the Visuals Arts serves as an approach to investigate, create, understand, accept, and confront the darkness within the artist's psychological and emotional state. Inspiration taken from vibrant colors and insects found within Puerto Rico's natural sources, how these interact, relate, and consume the human within. By creating a series of artworks, the artist starts to comprehend how silence has taken over her life. Taciturnity has become the flame that ignited the artistic flow that leads to the …

The Correlation Among Metabolic Syndrome Risk Factors, Hemodynamics, And Arterial Elasticity In Hispanic College Students, Paloma J. Mendoza

Theses and Dissertations

PURPOSE: The purpose of this study was to determine the correlation among MetS risk factors, hemodynamics, and arterial elasticity in Hispanic students attending The University of Texas Rio Grande Valley.

RESULTS: Systolic blood pressure (SBP), diastolic blood pressure (DBP), and fasting glucose (GLU) were the only components of MetS that had a significant correlation with large arterial elasticity (SPB: males: -.477 and females: -.503; DBP: females: -.300; p

CONCLUSION: MetS risk factors significantly correlated with both arterial elasticity and hemodynamic components. Uniquely in this population, waist circumference and systemic vascular resistance was reversely associated.

Genetics And Morphology Of Invasive Tubastraea Species Within The Gulf Of Mexico: A Case Study Of Species Misidentification And Distribution, Amelia E. Mcclure

Theses and Dissertations

The invasive corals, Tubastraea coccinea and Tubastraea micrathus, are known to thrive in reefs within the Gulf of Mexico (GOM). Many studies have indicated that species within this genus are spreading throughout the western Atlantic due to their successful invasion on degraded and artificial reef systems. In the Northern GOM, artificial reefs have been created from decommissioned oil rigs and sunken vessels to provide a hard substrate for coral growth. Although, this method is demonstrating success, it is also facilitating, the dispersal of undesired species. The species, T. coccinea and T. micranthus, were thought to be the only …

Investigating The Use And Effectiveness Of The Istation Advanced Reading Program With Fourth-Grade At-Risk Struggling Readers, Andres Martinez

Theses and Dissertations

The purpose of this study is to investigate the effects of computer-based-instruction (CBI) and multimedia when used as an intervention with upper elementary students experiencing reading difficulties on the State of Texas Assessment of Academic Readiness (STAAR) Reading Assessments. The researcher employed a quantitative, causal-comparative research design for this study. A Texas supplemental reading program, the Istation Advanced Reading Program, was used as a Response to Intervention (RTI) for those at-risk students of failing their Reading STAAR Test in the fourth grade and to sustain an effective reading program district-wide.

Archived data was collected from three South Texas Title I …

Measuring Disaster Resiliency In The Rio Grande Valley, Alma R. Provencio

Theses and Dissertations

People are now becoming more conscious of the effects of climate change. They are seeking to understand how to manage their resources and prepare for when a disaster strikes. The growing studies of disaster resilience lend that opportunity. In this spatial and temporal study, disaster resilience was measured for each census tract within the four counties of the Rio Grande Valley. Utilizing GIS tools and methods, the study examines resilience patterns between 2010 and 2017.

Results showed that even though various census tracts from each of the four counties increased in resilience from 2010 to 2017, the overall total resilience …

A Landscape-Scaled And Community Ecology Approach To Wildlife Corridor Design In South Texas, James A. Stilley

Theses and Dissertations

A formidable challenge in landscape ecology is developing a sound resolution to mitigate the impacts of habitat fragmentation and restore connectivity to a degraded landscape. The problem is worldwide landscapes are becoming primarily anthropogenic and areas set aside for wildlife are small and isolated. Researchers’ have developed the concept of the wildlife corridor to mediate this situation but a proper methodology to implement this concept is still in its infancy. This study aims to uncover a quantitative and repeatable wildlife corridor design methodology based on the least cost analysis strategy with both a singular focal taxa approach and a comprehensive …

A Sinking Feeling: The Fate Of Concrete Pyramids Deployed In Artificial Reefs In The Texas Gulf Of Mexico, Cameron J. Moody

Theses and Dissertations

The deployment of 2,611 concrete pyramids in Texas gulf waters represents a significant undertaking. In collaboration with Texas Parks and Wildlife, bathymetric sidescan data was collected at three reefs hit by Hurricane Harvey from 2017 to 2019. All reefs lost significant pyramid height between 2017 and 2019. The pyramids demonstrated greater subsidence in the year when Harvey occurred and minimal subsidence the following year. Pyramids that moved outside the reefs were due to hurricane forces and shrimp trawl activity. Pyramids that remained inside the reef remained at their deployment location for two reefs. The pyramids remaining in the third reef …

Identifying The N Sources For Black Mangrove (Avicennia Germinans) In A South Texas Mangrove Forest, Ashley Elizabeth Murphy

Theses and Dissertations

Black mangrove (Avicennia germinans) in south Texas provide ecosystem services and benefits to humans including: habitat for wildlife, prevention of coastline erosion, and mitigation of natural disasters. One step to preserve their ecological functions is to identify and protect the source of their nitrogen (N). Nitrogen stable isotopes were sampled for one year beginning August 2018 and used as tracers to identify how mangroves obtain N. Total N in (A. germinans) and associated (Batis maritima) (plants) (2.1%) was more abundant than in cyanobacteria (0.6%) and sediment (0.1%). Plant d15N signatures (5.52‰) were more similar to sediment (5.21‰) than cyanobacteria (1.98‰), …

Evaluation Of The Most Significant Factors Influencing The Production Rates Of Highway Construction Activities, Angelica M. Neira

Theses and Dissertations

The utilization of realistic production rates is key for the accurate estimation of the contract time in highway projects. Several factors have an impact on production rates and change the total duration of construction projects. To organize and complete projects in a timely, quality and financially responsible manner, projects need to be scheduled carefully. Schedulers and planners of the Texas Department of Transportation (TxDOT) have been noticing that the estimated timelines are far from the reality and want to investigate if external factors can be the cause of this discrepancy. Some of the factors considered in this study are the …

Characterization Of Plasmids Harbored By Vibrio Cholerae Isolates Endemic To The Rio Grande Delta, Viviana Trevino

Theses and Dissertations

Cholera is a diarrheal disease responsible for considerable morbidity and mortality globally. Epidemics along the Rio Grande Delta were reported during the 1850s, and the etiological agent Vibrio cholerae, remains endemic, thus presenting a unique opportunity for a study of historical and biological relevance. V. cholerae strains were isolated from two locations: the Rio Grande River under a bridge linking Brownsville to Matamoros (site 21) and where the river empties into the Gulf of Mexico (site 42). Two strains from site 21, and one from site 42 were selected to isolate, subclone, sequence, assemble and annotate extra-chromosomal elements. Results …

Identity Fluidity, Empowerment, And Engendered Poverty: Performing A Veteran-Latina-Online-Graduate Student, Maricela Burns

Theses and Dissertations

The goal of this project is to use critical race theory and gendered discourse to shed light on engendered poverty, cultural capital and resilience in efforts to identify how the American educational system affects marginalized groups when the systems of power and privilege were not created for them. It is through a poignant narrative of one of these students (myself) in the educational system that I reflect, recollect, write and interweave my lived curriculum with what the literature says about ethnic experiences like mine. The efforts here serve to analyze the processes of constructing and building social and gender identity …

The Role Of Sediment Resuspension In Estuarine Inorganic Nutrient Cycling, Kirsten Jo Ayres

Theses and Dissertations

Time-scaling of estuarine inorganic nitrogen cycling contains many assumptions due to biogeochemical interactions. Nitrogen, often a limiting factor for primary production, is transformed and utilized by many estuarine organisms. Inorganic nitrogen is especially high in porewater. High nutrient pore water, contained within the interstitial spaces of sediment, has been assumed to influx high concentrations of inorganic nutrients into surface waters during resuspension events. These short-term resuspension events rapidly introducing high concentration of nutrients into the water column. In order to determine the internal time scale of inorganic nitrogen cycling, a box-model nutrient budget, horizontal in situ transects, and vertical nutrient …

Enabling High Quality Oxygen Measurements During Robotic Based Studies Of Ocean Ecological And Biogeochemical Processes, Brianna A. Alanis

Theses and Dissertations

Dissolved oxygen is an essential parameter necessary for understanding marine ecological and biogeochemical processes. New robotic vehicles and autonomous platforms are being applied to an even wider range of ecological and biogeochemical studies. Thus, arises the opportunity for matching the best possible oxygen sensing techniques and methods to these new platforms. In so doing, we can enable both more targeted and higher resolution oxygen measurements than previously possible and potentially use oxygen measurements for a wider range of applications, including in situ incubation experiments and primary productivity measurements. This thesis tested three different oxygen sensors in a trade study for …

Genetic Determinants Of Variation In The Gh/Igf-1 Axis And Their Relationship To Cardiometabolic Health, Rafael Luis Aguirre Guillen

Theses and Dissertations

Background: In a study of Mexican Americans, we performed analyses of GEI and pleiotropy in the axis in relation to MS. GH/IGF-1 axis components were studied. Model parameters and likelihoods were estimated by maximum likelihood.

Results: Pleiotropy was observed for IGFBP3 (p

Conclusions: IGF-I and IGFBP3 are genetically correlated with MS whereas MS influences the additive genetic variance in IGFBP1 variables mainly but also in IGF-I somewhat by virtue of the VH exhibited by IGF-I/IGFBP1.

Gulf Trade Networks And Family Ties: French Migration Via New Orleans To The Lower Rio Grande Valley, 1848-1881, Kristen D. Kline

Theses and Dissertations

This thesis considers economic and social aspects of French immigration to the Lower Rio Grande Valley (LRGV) of Texas during the mid-nineteenth century, with special emphasis on a small group of merchants who left France during the 1850s. It synthesizes the work of several scholars who have focused on French presence in the LRGV with others who have analyzed various economic facets of the LRGV during different periods between the eighteenth and twentieth centuries. This study attempts to situate five families into the context of nineteenth-century European migration to the Americas, as well as into the Gulf maritime economy on …

A Critical Bricoleur Assumes Positive Intent: Pablito's Problem, Paul Perez-Jimenez

Theses and Dissertations

This dissertation serves to further critical theory research through bricolage autoethnography of a Latinx English teacher from the Rio Grande Valley of Texas. The bricolage functions to unify reflective constructs that expose an emancipatory catharsis and painful reacquaintance with individual and cultural identity. This project offers the concept of a happening as a construct embedded with the ongoing, reflective, and liberating critical consciousness process. Four happenings are offered and establish that the dichotomies of oppression and liberation, how they happened, are happening or may happen are not easily recognizable unless critical introspection is involved. The leading happening titled Pablito’s Problem …

Dna Barcoding Reveals Unexpected Diversity In Octocorallia In The Northwestern Gulf Of Mexico, Chelsea L. Pavliska

Theses and Dissertations

Coral reefs are an integral tier of marine ecosystems. They provide habitat and foraging opportunities for many ecologically and economically important fishes. Protection of coral reef biodiversity and connectivity is imperative to the continued health and sustainability of marine fisheries. Mesophotic reefs, such as those found in the northwest Gulf of Mexico, have unique coral communities because of the limited light penetration at mesophotic depths (30 – 150m). Because there is limited knowledge in regards to the biodiversity of coral reefs of the northwestern Gulf of Mexico (GOM), particularly the South Texas Banks (STBs), thesis work presented here aims to …

Detecting Phone-Related Pedestrian Behavior Using A Two-Branch Convolutional Neural Network, Humberto Saenz

Theses and Dissertations

With the wide use of smart phones, distraction has become a major safety concern to roadway users. The distracted phone-use behaviors among pedestrians, like Texting, Game Playing and Phone Calls, have caused increasing fatalities and serious injuries. With the increasing usage of driver monitor systems on intelligent vehicles, distracted driver behaviors can be efficiently detected and warned. However, the research of phone-related distracted behavior by pedestrians has not been systemically studied. It is desired to improve both the driving and pedestrian safety by automatically discovering the phone-related pedestrian distracted behaviors. In this thesis, we propose a new computer vision-based method …

Women In Law Enforcement: The Impacts And Obstacles They Face In A Hispanic- And Male-Dominated Culture, Lisa M. Seiser

Theses and Dissertations

Despite a lack of female law enforcement representation in police departments across the country and especially in the Border Patrol, there have been minimal studies performed that focus on the obstacles women face in these professions. The purpose of this study was to attempt to understand the lived experiences of female law enforcement officers/border patrol agents in this male-dominated profession, but also adding the aspect of them working in a Hispanic-dominated culture.

The findings revealed these women in law enforcement working in a Hispanic area face many of the same obstacles as women in other parts of the country - …

Elementary Statistics Instructors' Uptake Of The Teaching Practices Recommended By The American Statistical Association, Marisol Sanchez Cortez

Theses and Dissertations

Previous studies point out there has been a wide gap, in the teaching of mathematics, between the practices recommended in the credential programs and the practices teachers actually do. The purpose of this study is to explore how consistent the teaching practices of introductory statistics instructors are to the recommendations endorsed by the American Statistical Association, to understand what their attitudes to the gap are, and to identify the factors that prevent the instructors from implementing the recommended practices. Data were collected from nine statistics instructors at a state university through survey, classroom observations, and interviews. Findings indicate that the …

An Advanced Approach For Contract Time Determination In Highway Projects, Cuauhtemoc Torres Cantu

Theses and Dissertations

In project management, finishing a project on schedule is one of the most important aspects. The Texas Department of Transportation (TxDOT) has been experiencing delays in some projects that can be accounted to an inaccurate project time estimation process. This research presents the development of a user-friendly and comprehensive computer-based contract time determination system. The enhanced system implements probabilistic scheduling techniques such as Program Evaluation and Review Technique, and Monte Carlo Simulation. Additionally, the application of a lognormal two-point PERT method is explored in this study. The new system proposes the use of a database of production rates based on …

Degree Of Bilingualism, Age, Income And Teacher Ratings Of Giftedness As Potential Predictors Of Dichotic Listening Performance, Francisco J. Sierra

Theses and Dissertations

Bilinguals and gifted individuals have consistently shown distinctive patterns of performance on measures of brain laterality and auditory processing. The purpose of this study is to examine the relationship between bilingualism, teacher ratings of giftedness, and auditory divided attention by comparing children and adults with income partialed out. Child participants from first to fifth grade were included in addition to an adult comparison group. Assessment of bilingualism, auditory divided attention, and giftedness occurred via the Woodcock-Munoz Language Survey-III (WMLS-III), the Dichotic Test of Attention (DITA), and the Hispanic Bilingual Gifted Screening Instrument (HBGSI). The main hypothesis of this study is …

Graphene-Fibers Hybrid Structures As Adsorbents For Heavy Metal Ions In Aqueous Solutions, Dulce C. Capitanachi

Theses and Dissertations

The project focuses on the study of graphene-fiber hybrid structures for adsorption of heavy metal ions in aqueous solutions. Polyvinyl alcohol-based graphene–fiber structures were created using centrifugal spinning and a carbonization process.

Characterization methods of the graphene–fiber hybrid structures (GFHS) include SEM, FTIR, TGA, and EDX. Single-step batch-type adsorption studies were performed to analyze the interaction of Cu (II) and Pb (II) ions onto GFHS surface. Different heavy metal ion concentrations were used, as well as a variation of pH values. Elemental analysis of the adsorbent’s surface after filtration experiments was studied by EDX and spectroscopy to verify the presence …