Digital Commons Network^™

Identification Of Inhibitors Of The Glutaminyl And Prolyl Trna Synthetases From Pseudomonas Aeruginosa, Yaritza Escamilla

Theses and Dissertations

Antibiotic resistance is a growing global threat and bacterial infections caused by antibiotic resistant bacteria have become increasingly difficult and expensive to treat with most current antibiotics. Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen and a leading cause of nosocomial infections and is the leading cause of mortality in cystic fibrosis patients. Aminoacyl-tRNA synthetases (aaRSs) are a class of enzymes that catalyze the covalent attachment of amino acids to their cognate tRNAs during protein biosynthesis. The glutaminyl- tRNA synthetase from P. aeruginosa was over-expressed, enzymatically characterized and developed into a screening platform for the discovery of chemical compounds that inhibit …

A Case Study Of Hispanic Stem Teacher Preparation, Pamela L. Groves

Theses and Dissertations

There is a shortage of Science, Technology, Engineering, and Mathematics (STEM) teachers in the US (Aragon, 2016; National Science Board, 2003). Hispanics are underrepresented in STEM teaching (Aragon, 2016; Texas Education Agency, 2017; US Census Bureau, 2016b; US Department of Education, n.d.). In order to improve the state of STEM teaching in the US we must tap into this underrepresented group. This exploratory case study examined the experiences of Hispanic students pursing STEM teacher preparation and how the UTeachRGV program impacts student persistence and retention.

UTeachRGV is a STEM teacher preparation program at the University of Texas Rio Grande Valley …

Effects Of Elevated Temperature On Gonadal Functions, Cellular Apoptosis, And Oxidative Stress In Atlantic Sea Urchin (Arbacia Punctulata), Jackson B. Johnstone

Theses and Dissertations

Increasing surface sea water temperatures effect on growth, reproduction and development in marine organisms. Sea urchins are excellent indicator species and ideal model organisms to focus on. In this study, I tested the effect of higher temperatures on reproductive functions, heat shock protein (HSP, a chaperone protein produced by cells in response to heat stress) and nitrotyrosine protein (NTP, an indicator of reactive nitrogen species, RNS) expressions, cellular apoptosis, and ceolomic fluid (CF, a body fluid which regulates important physiological processes) conditions in Atlantic sea urchin at three different temperatures. Ten sea urchins were placed in each of six aquariums …

Contributions Of Historical Ecology To Ecological Services Assessments In The Lower Rio Grande Valley Texas, Julianna Katherine Schaefer Kurpis

Theses and Dissertations

Historic and current anthropogenic land-use activities affect ecological functions and ecosystem services quality. The clearing of native Tamaulipan thorn forest and riparian forests for agricultural use and expansion followed by rapid urbanization and population growth resulted in profound ecological impacts to the Lower Rio Grande Valley (LRGV), Texas. The goals of this study are 1) document trends in land use change and vegetation health in the LRGV 2) evaluate and demonstrate the application of the Ecosystem Services Identification & Inventory Tool (ESII Tool) for collecting ecological data and measuring percent ecological performance and 3) use historical ecology indicators to compare …

A Snapshot Of The Age, Growth, And Reproductive Status Of Gray Triggerfish (Balistes Capriscus, Gmelin 1789) On Three Artificial Reefs In The Northwest Gulf Of Mexico, Adam M. Lee

Theses and Dissertations

Age, growth, and reproductive status of gray triggerfish (Balistes capriscus) were identified from 2015-2016 on artificial reefs in the northwest Gulf of Mexico. Individuals ranged from 232-432 mm fork length with and a mean fork length of 319 mm. Individuals from age 0.2 to 5.2 yrs were observed with a weight to length relationship of Wg = 1.1 x -104 x FL2.7 (r2 = 0.94, n = 112), where FL = fork length (mm) and Wg = weight (g). A von Bertalanffy growth equation of Lt = 326(1 - e - 0.9 (t + 1.71)) was calculated irrespective …

The Snail Communities Of The Lower Rio Grande Valley, Briante Shevon Lewis Najev

Theses and Dissertations

The lower Rio Grande Valley are three lowest latitudinal counties of south Texas. This unique, subtropical, semi-arid environment has the last remaining Tamaulipan Thornforest in the USA. The Tamaulipan Thornforest of Texas occupies less than 2% of their former range. Before this habitat possibly dwindles even more there has been a comprehensive survey of terrestrial snails in intact, altered, and urban areas of the valley.

We have found a 16397 of snails in intact sites with a high species richness at 17; followed by altered sites with an abundance of 12143 snails and a species richness of 15. There were …

Polymeric Pvdf Fibers For Piezoelectric Applications In Energy Harvesting, Misael E. Martinez

Theses and Dissertations

This work focuses on developing and characterizing the piezoelectric response of Cerium doped Polyvinylidene Fluoride (PVDF) fine fibers and the effects of dopants and alignment on the formation of the β-phase and consequently on the piezoelectric performance. Six sets of fiber mats were prepared varying the concentration (2.5–7.5wt%) of Cerium (III) Nitrate-Hexahydrate and Ammonium-Cerium (IV) Sulfate-Dihydrate. Fiber mats were developed using the Forcespinning® technique and the angular velocity and dopant concentration were adjusted to obtain a synergy between fiber yield and fiber diameter. Fourier Transform Infrared Spectroscopy showed a significant enhancement in the PVDF β-phase and inhibition of the non-polar …

Investigating The Efficacy Of Jak2/Stat3 And Pi3k/Mtor Inhibitory Therapy On Glioblastoma And Basal Breast Cancer Cell Lines, Neftali Vazquez

Theses and Dissertations

The JAK2/STAT3 and PI3K/mTOR pathways are upregulated in cancer cells. STAT3 promotes a positive feedback loop for the stem program whereas PI3K inhibits FOXOs tumor suppressor role and mTOR promotes tumorigenic advancement. Particularly GBM and BBC are aggressive cancers that have a stem cell population that makes them difficult to treat and metastatic. We investigate the effects of a combination therapy that inhibits JAK2/STAT3 and PI3K/mTOR output aiming to lower stem cell expression and promote apoptosis. Our collected data indicates that the dual inhibition induced apoptosis, but it also increased the stem cell signature. The findings pave way for the …

Effects Of Global Warming On Gonadal Functions, Cellular Apoptosis, And Oxidative Stress In The American Oyster, Sarah B. Nash

Theses and Dissertations

Global warming due to climate change is predicted to intensify the heat stress in marine and coastal organisms, affecting their development, growth and reproductive functions. In this study. I analyzed gonadal development, heat shock protein 70 (HSP70), nitrotyrosine protein (NTP), dinitrophenyl (DNP) expressions, cellular apoptosis, and coelomic fluid (CF) conditions in American oyster. Oysters were placed in six aquariums and exposed to control (24°C), medium (28°C), and high (32°C) temperatures for one week. Higher temperature significantly decreased the number of eggs and sperm. CF protein concentrations also declined compared to control. In contrast, CF pH and HSP70 expression in gonad …

Curriculum Change: A Study On Teacher Perceptions Of Curriculum Change On Content Standards, Tiffany Kessler-Hopek

Theses and Dissertations

In the United States, curriculum has encountered frequent changes throughout years. The main initiative of educational change has three main components, and they are to increase the quality and rigor of the curriculum, have a common curriculum, and prepare students for secondary education. The standards in the state of Georgia have changed from Georgia Performance Standards and Common Core State Standards to the more recent Georgia Standards of Excellence. By the school year 2018-2019, the Georgia Standards of Excellence should be fully adopted. An explanatory sequential mixed methods study was conducted to examine the perceptions of teachers on curriculum change …

Factors Related To The Assessment Of The Effectiveness Of Environmental Management Systems (Ems) At Airports, Kainan Li

Theses and Dissertations

The purpose of this study was to identify factors that can be used to assess the effectiveness of EMS at airports in the United States (U.S.). A survey research methodology was used for this study in two phases. The first phase of the research study included a preliminary expert opinion survey of airport managers and other individuals acting in a supervisory role to determine and discuss how EMS help improve environmental performance, and ranked factors that may be related to assessing the effectiveness of EMS. The second survey was constructed based on feedback from these experts and targeted airport employees …

Smartphone Use In Children’S Shows: A Qualitative Content Analysis, Dylan Mckinley Fleming

Theses and Dissertations

This study analyzes media messages through the lenses of social cognitive theory and cultivation theory. Specifically, this study focuses on messages about smartphone use in children’s cartoons. This study found smartphones are portrayed in a positive manner in the majority of the episodes. Themes of smartphone use included learning, helping, and increasing social standing in the case of capturing content for vlogs. Characters who modeled smartphone use were brave and helpful, but in some cases distracted. Outcomes for smartphone use were overwhelmingly positive. Based on the widespread usage of smartphones in real life, smartphone usage is only going to become …

Resilience To Post-Traumatic Stress Symptoms In Child Survivors Of Childhood Sexual Abuse, Caroline Witek

Theses and Dissertations

Just as adults may develop post-traumatic stress disorder (PTSD) after being exposed to death, serious injury, or sexual violence, so too may children. Childhood sexual abuse (CSA) is one traumatic event that has been linked to the development of post-traumatic stress symptoms (PTSS) in children. While the literature to date has drawn strong connections between CSA and subsequent psychopathology (including PTSD diagnoses), and explored factors contributing to resilience to psychopathology development, comparatively little research has been conducted on factors that increase child CSA survivors’ resilience to post-traumatic stress symptom development. Furthermore, much of the research to date has explored long-term …

Validation Of An External Bioreactor Filtration Loop Prototype For A Tissue Engineering Test Bed, Jonah Martin Melegrito

Theses and Dissertations

As a cell line thrives within a culture, some of the cells undergo the natural process of death. Whether it is due to apoptotic or necrotic causes, cell death is a significant hurdle for tissue engineering and cell cultivation. When cells attached to a scaffold die, they slough off from the scaffold into the bloodstream. If left unchecked, these dead cells and any cellular waste products accumulate and could affect the living cells’ ability to survive. The objective of this thesis was to construct a separation system that can filter away any unwanted suspended solids while allowing nutrients to recycle …

Residence Time Distribution (Rtd) Analysis Of A Bioreactor's External Recirculation Loop For A Tissue Engineering Test Bed, Adrien Hosking

Theses and Dissertations

Currently, in tissue engineering, the focus is on morphing cells into a particular type of tissue by hand, rather than automating the process. Automating cell feeding and waste removal, alone, still requires the removal of cells from their culture to perform imaging and analysis. Without the ability to automate the imaging in a way that does not risk cell death, the advantages of automating the feeding and waste removal are largely lost. By building a fully automated tissue engineering test bed, the capacity for cell reproducibility and cell yield increases significantly. This thesis outlines the design, some initial testing, and …

Design And Synthesis Of 5-Oxo-Ete Receptor Antagonists; And Synthesis Of Neuroprostanes As A Biomarker For The Diagnosis Of Alzheimer’S Disease, Rui Wang

Theses and Dissertations

1) 5-Oxo-ETE (7, Scheme 1) is the most potent eosinophil chemoattractant among all lipid mediators and it can also stimulate a late-phase asthma attack. It is formed by the biotransformation of arachidonic acid (AA, 1, Figure 1). 5-Oxo-ETE (7) elicits eosinophil migration both in vitro and in vivo when injected intradermally in humans, acting via the highly selective OXE receptor (OXE-R). Our group postulated that a selective OXE-R antagonist might be a useful therapeutic agent in late phase asthma. As a result, the first and only series of OXE receptor antagonists which are structural mimics of 5-oxo-ETE (7) have been …

Hrv - Ecg Generator: Software For Testing Heart Rate Variability Detection, Matthew Joseph Pogorelec

Theses and Dissertations

Heart rate variability (HRV) has been shown to serve as an effective diagnostic and prognostic tool in a variety of clinical applications, including for patients who have suffered from myocardial infarction, sepsis and liver cirrhosis. There currently exist a variety of devices and software to quantify HRV based on RR interval series collected from ECG data. However, as the uses for HRV expand, a greater variety of devices for different applications are being designed and developed. Thus, it is useful to have available a method for efficiently testing preliminary software. The HRV/ECG Generator software is designed to build both an …

Synthesis Of Photoactive Molecules And Silicon Containing Compounds, Mozhgan Navidi

Theses and Dissertations

Retinoids are a class of synthetic and natural molecules that are functionally and structurally related to Vitamin A. They have various biological roles and potential therapeutic values. Providing treatment for eye diseases requires more detailed understanding of the visual process. However, investigating every aspect of the visual phenomenon is constrained by the difficulties involved in the synthesis of pure retinoids with the desired stereochemistry. Therefore, developing a suitable and valuable synthetic route for 11-cis-retinal and its analogues is highly desirable. The first chapter of this dissertation explains new synthetic pathways for 11-cisretinal. In addition, the total synthesis of stereoselectively deuterium-labeled …

Photocleavable Endogenous And Exogenous Molecules, Charitha Madhusanka Guruge

Theses and Dissertations

The spatiotemporal regulation of biomolecules in their physiological environment is an essential aspect of biological research. In neuroscience, the activity of neurotransmitters can be regulated by protecting the molecules with photoresponsive protecting groups (PPGs), also known as cages. Diverse set of PPGs have been developed for caging of biomolecules. PPGs can be categorized based on their absorbing wavelengths (ranging from UV to near-IR) and photochemical properties (quantum yield, photo-cross section, solubility). PPGs absorb light and undergo intramolecular electron transitions and bond rearrangements that result in the release of the caged substrates. Hence, the caging of a specific substrate is unique …

Vegetation Response To Intense Holocene Dry Events In The Andes And Amazon Basin, Majoi De Novaes Nascimento

Theses and Dissertations

By using the natural laboratory of past climate change I ask: How resilient are extant tropical forest ecosystems to climatic forcing? Do tropical forests systems show gradualistic or threshold responses to past climate change? How do climate forcings change floristic composition? And do humans amplify or suppress the effects of natural climate variability through land use? My study is set in western Amazonia and in the eastern flank of the Andes, regions renowned for high endemism and cultural importance. The time scale of the study spans the Mid-Holocene Dry Event (MHDE, c. 9000 to 4000 years ago), arguably the most …

Ontogeny Of Similarity And Disparity In Length-At-Age Of Coral Reef Fishes In The Family Acanthuridae Between Marine Protected And Fished Areas, Mathias Tjarko Cramer

Theses and Dissertations

Drastic reductions in the harvestable biomass of exploited fish populations on coral reefs and other marine coastal ecosystems have been hypothesized to be a consequence of astronomical and unrelenting fishing pressures, particularly in the coastal small-scale and sustenance fisheries of the world. It has recently been proposed that the causal relationship between fishing pressure and fish biomass is rooted in the negative effects of size-selective fishing mortality, which consequently instigates directional shifts in phenotype (i.e., fishing induced evolution). To mitigate the effects of unsustainable fishing pressures, parcels of traditional fishing grounds have been designated as Marine Protected Areas (MPAs). To …

Ecological Responses To Eutrophication And Restoration In A Shallow Subtropical Estuary, Xiao Ma

Theses and Dissertations

Like many other estuaries in the world, the Indian River Lagoon (IRL) is experiencing serious environmental health challenges in recent years. Ecosystem challenges include the connected phenomena of Harmful Algal Blooms (HABs) due to eutrophication and accumulation of fine-grained organic-rich sediments on the benthos. Fine-grained organic-rich sediments, referred to as “muck”, is a source of nutrients and fuels algal blooms in the water column, and excess particles associated with algal blooms sink to bottom and contribute to muck. This dissertation aims to better understand these problems by addressing two main objectives: first, to determine whether key herbivorous mesozooplankton have the …

Formal Trust Architecture For Assuring Trusted Interactions In The Internet Of Things, Milankumar Patel

Theses and Dissertations

The Internet of Things (IoT) has provided a flexible platform for a large number of heterogeneous devices to dynamically join and leave the network. This enhances the availability of a diverse range of services provided by a network. However, this dynamic expansion of the network with mobile IoT devices introduces a major challenge to security especially related to management of trust across the IoT platforms. Furthermore, IoT is open and distributed in nature, which allows the integration and registration of diverse entities. Thus arises the necessity for a mechanism that can ensure the selection of secure and trusted devices as …

Qualitative Analysis Of The Nonlinear Double Degenerate Parabolic Equation Of Turbulent Filtration With Absorption, Adam Prinkey

Theses and Dissertations

The goal of the dissertation is to pursue qualitative analysis of the mathematical model of turbulent polytropic filtration of a gas in a porous media with reaction or absorption described by the second order nonlinear double degenerate parabolic equation ∂u ∂t − ∂ ∂x F [ ∂u m ∂x ] + Q(u) = 0, (1) where F(y) = |y| p−1 y, Q(u) = buβ , m, p, β > 0, b ∈ R. In the absence of the reaction term there is a finite speed of propagation with an expanding interface in the case of slow diffusion (mp > 1), and infinite …

Parametric Methods For Analysis Of Survival Times With Applications To Organ Transplantation, Farag Hamad

Theses and Dissertations

In this dissertation, we have two main objectives. First, we introduce a hybrid method to model hazard function. Different approaches have been used for modeling survival times including parametric, semi-parametric, and non-parametric models. Non-parametric and semi-parametric models are commonly used for survival time analysis due to their flexibility. However, the parametric models are in high demand because of their predictive power. A challenging task is to extend semi-parametric methods and design full parametric models for analysis of survival times by estimating a set of unknown parameters. In the proposed method, the nonparametric estimate of the survival function by Kaplan Meier …

Object Enhancement, Noise Reduction, Conversion And Collection Of Spatiotemporal Image Data, Michael Izaguirre Jr.

Theses and Dissertations

In this report, a variety of cellular dynamics are enhanced and analyzed utilizing various algorithms and filter for contrast enhancement. This report will also illustrate the underlying complexities of processing compressed data received from certain type of sensors, their default applications, various methods in converting compressed data to compatible universal uncompressed formats allowed in scientific applications, various methods of image and video capture, guidelines in ethical image manipulation, various methods of frame extraction, and analyzing/processing video images. These methods and processes purposely utilize freeware and public domain software to lower the cost of reproducibility for all.

Comparative, Lithology-Based Biogeography Of Phreatophytic And Non-Phreatophytic Matrices Along A North-South Gradient Of The South Texas Sand Sheet, Christopher Joaquin Munoz

Theses and Dissertations

A 70km-long, N-S stratigraphic cross-section spanning the entirety of the South Texas Sand Sheet (STSS) has been rendered along Texas Interstate 69C. The cross-section indicates localized zones of substantial STSS thickness (>4m) as well as zones where the underlying Goliad Formation is either exposed or just below the surface (<0.5m). Spatial patterns of both phreatophytic and non-phreatophytic vegetation assemblages were analyzed by means of remote sensing and in situ herbaceous species evaluations. Biogeographic patterns were comprised of three vegetation matrices: P. glandulosa-dominated, Q. virginiana-dominated and a matrix of herbaceous plants. The geographic distribution of vegetation assemblages corresponded to specific lithological parameters and features. Namely, Q. virginiana concentration exhibited a positive linear relationship with the lithological parameter of STSS thickness (P =2.122x10-11) (α = 0.05). P. glandulosa/V. farnesiana …

High-Powered Led Assembly As Replacement For Conventional Hbo Lamps In High Resolution, High Magnification Microscopy System, Christian Y. Miranda Solis

Theses and Dissertations

Through decades, fluorescence microscopy has relied on mercury vapor lamps as its main light source due to their high power, broad spectrum, and bright bands generated. The use of mercury vapor lamps has remained fundamentally associated with the required lighting equipment of research laboratories. However, as time progresses, mercury vapor lamps have been slowly replaced with technologies that offered longer lifetimes, less hazardous waste, and output light at similar intensities. LED technology has been actively used in biological research, but was limited by price, lower intensities, and stability. The recent development of LED technology has allowed for further understanding and …

Investigating Limitations To Nitrogen Fixation By Leguminous Cover Crops In South Texas, Stephanie L. Kasper

Theses and Dissertations

Many farms use leguminous cover crops as a nutrient management strategy to reduce their need for nitrogen fertilizer. Biological nitrogen fixation (BNF) depends on a symbiotic relationship between legumes and nitrogen-fixing rhizobia. Under certain conditions despite inoculation with appropriate rhizobial strains, this symbiosis fails to form. Such failure was observed in a 14-acre winter cover crop trial in the Rio Grande Valley of Texas when three legume species (forage pea, crimson clover, and hairy vetch) produced no signs of nodulation and nitrogen fixation. This study examined nitrogen, phosphorus, moisture, micronutrients and biotic interference as potential causes for the failure and …

Early Educator Awareness Of Autism Spectrum Disorder In Preschool Hispanic Populations, Karla Cecilia Vidaurri

Theses and Dissertations

Christensen et al. (2016) highlights how "there are disparities by race/ethnicity in estimated ASD prevalence, particularly for Hispanic children, as well as disparities in the age of earliest comprehensive evaluation and presence of a previous ASD diagnosis or classification, suggesting that access to treatment and services might be lacking or delayed for some children" With an increase in autism prevalence and Hispanic population, there's a crucial demand for effective servicing and referrals for early identification of Autism.

The aim of this study was to analyze how prepared early educators are in identifying children that fall under the category of autism …