Digital Commons Network^™

Development Of A Framework For The Calibration Of Rpas, A 3d Finite Element Analysis Tool For Rigid Pavements, Abbasali Taghavighalesari

Open Access Theses & Dissertations

The accurate analysis of rigid pavements requires a reliable modeling procedure based on integrating mechanistic analysis methods (i.e. closed-form solutions or numerical methods) and empirical observations (i.e. field measurements and laboratory test results). The use of the finite element method to model the response of rigid pavements has increased in recent decades due to its capability to incorporate the complexity of material behavior, traffic information, and environmental condition. Researchers from the University of Texas at El Paso developed the software Rigid Pavement Analysis System (RPAS) to comprehensively analyze the response of concrete pavements under different geometric configurations, foundation models, temperature …

Development And Validation Of The Perinatal Mental Health Literacy Scale Among Latinas, Irma Y. Torres-Catanach

Open Access Theses & Dissertations

Psychiatric disorders in pregnancy and in the first year after childbirth are considered a significant health complication of the perinatal period (O'Hara & Wisner, 2014). The prevalence of perinatal mood disorders has been shown to be higher among women from racial/ethnic minority groups (Gavin et al., 2011; Melville et al., 2010). As the largest racial/ethnic minority group in the U.S., Latinas are disproportionately affected by these disparities. Despite the volume of research examining the prevalence of and treatment for perinatal psychiatric disorders, there is a dearth of knowledge focused on educational approaches that aim to reduce perinatal mental health disparities. …

Secondary Student Perceptions Of School Climate Elements And Self-Reported Academic Self-Efficacy As Factors Of School Continuous Improvement, Marianne Arzadon Torales

Open Access Theses & Dissertations

State and national agencies recognize the link between school quality and student academic and behavioral outcomes. Research has shown that a positive school climate and high academic self-efficacy are associated with positive academic and behavioral student outcomes. Determining the school climate factors that contribute to academic self-efficacy will add to the limited research on the relationship between these two constructs and provide information to prospective and current school leaders in cultivating an effective school.

A multiple regression was used to determine how student-perceived school climate factors predict self-reported student academic self-efficacy and of these factors, which one provided the strongest …

Applications Of Ornstein-Uhlenbeck Type Stochastic Differential Equations, Osei Kofi Tweneboah

Open Access Theses & Dissertations

In this Dissertation, we show with plausible arguments that the Stochastic Differential Equations (SDEs) arising on the superposition and coupling system of independent Ornstein-Uhlenbeck process is a new method available in modern literature that takes the properties and behavior of the data into consideration when performing the statistical analysis of the time series.

The time series to be analyzed is thought of as a source of fluctuations, and thus we need a model that takes this behavior into consideration when performing such analysis. Most of the standard methods fail to take into account the physical behavior of the time series, …

Photovoltage Enhancement For Stable Perovskite Solar Cells With A Temperature-Controlled Grain Growth Technique, Luis Eduardo Valerio

Open Access Theses & Dissertations

By performing strong characterizations methods, one can begin to fully understand the chemistry and composition behind a great performing perovskite solar cell. Understanding how the interaction between layers inside a solar cell is driven by the temperature and overall environment is a key element to improve the fabrication process and overall efficiency of such cells. This Thesis will present a study of the hybrid organic-inorganic, mixed-cation, mixed-halide, temperature and thickness-controlled perovskite solar cell. A constant power conversion efficiency (PCE) ranging between 15-17% and an open circuit voltage V¬oc above 1.05 V for a wide-band gap perovskite cell is presented.

The Effects Of Advancing Stages Of Pregnancy On Balance And Stair Locomotion In Healthy Females, Heather Vanderhoof

Open Access Theses & Dissertations

Background: One in four females fall while pregnant, which may lead to injury, hospitalization, or birth complications. No empirical research has been conducted on single-limb support (SLS) balance or joint kinematics during stair locomotion in pregnant and postpartum females. The aim of this study was to quantify possible alterations to postural control and stair kinematics in advancing stages of pregnancy when compared to non-pregnant females. Methods: This cross-sectional study compared eighteen females, consisting of six non-pregnant controls, five 2nd trimester, four 3rd trimester, and three postpartum. Center of pressure excursion area data were obtained during static balance trials on a …

Computational Methods For Creep Modeling, Ricardo Vega

Open Access Theses & Dissertations

Creep is an important phenomenon present in the power generation and aerospace industry. Creep is a mechanism that degrades the quality of a part, such as the turbines used in different industries, when elevated temperatures and loads are applied. Creep damage can cause critical failures that can cost millions of dollars and as such, prevention is important. A multitude of creep models exist to help with design and failure prevention. These models are applied using computational tools which allows the engineer to properly predict the life of a part or other material properties. In this work various creep numerical optimization …

Synthesis And Advanced Manufacturing Of Polymer Structures And Their Composites, Bethany Rose Wilburn

Open Access Theses & Dissertations

The following research work performed embodies three unique studies of polymer structures and their composites. In general, polymers are viscoelastic, insulative materials that are used for a wide variety of applications within industrial, aerospace, and biomedical fields. Polymers have been studied and optimized for any particular use by chemically synthesizing unique micro-structures, altering the physical properties through fabrication and post-processing, and utilizing 3D printing to achieve complex geometries. In the past decade, additive manufacturing (AM) has drawn extensive attention across academia, industry, and government agencies. It offers unprecedented advantages such as design freedom, rapid prototyping, and customization. In this work, …

Managerial Entrenchment And Financial Reporting Comparability, Qifeng Wu

Open Access Theses & Dissertations

This study examines whether managerial entrenchment has an association with firms' financial statement comparability. I find that managerial entrenchment has a significant negative association with financial statement comparability, providing a new notion about the management influence on financial reporting quality. Moreover, by using the business segment as a proxy for business complexity, I find that the variation of accounting comparability with its peer firms mainly stems from managers' investment choice. This finding supports FASB's assertion that financial statement comparability is a reporting quality that should be enhanced among firms with similar economic events. Lastly, I test if managerial entrenchment mitigates …

Characterization Of The Anti-Viral Activity Of Schlafen13, Jordan Winfield

Open Access Theses & Dissertations

Schlafen13 (Slfn13) is an enzyme that belongs to the Schlafen family whose expression and function is not very well characterized. The N-terminal has a pseudo dimer structure that contains its catalytic site. There is no characterization functionally or structurally of the C-terminal of Slfn13 other than the prediction of a region with helicase activity. The objective of my Thesis was to increase our understanding of the Slfn family of proteins. Currently, Slfn13 is reported to play a role in the differentiation of monocytes and to function as an endoribonuclease that cleaves tRNA and rRNA molecules in a site-dependent sequence-independent manner. …

Impact Of Interface Condition On Performance Of Thin Asphalt Overlays, Cheng Zhu

Open Access Theses & Dissertations

Asphalt overlay has been widely used in the United States as a cost-effective maintenance approach to keep the pavement in a satisfactory condition. In recent years, many studies have been conducted to investigate the overlay asphalt mix design, overlay pavement design, and quality control/quality assurance for the asphalt overlay pavement. In Texas, thin overlays (lift thickness less than 2 in.) and ultra-thin overlays (lift thickness of 0.5 in. to 0.75 in.) seem to be more beneficial than conventional asphalt overlays. For this type of overlay, the bonding condition between the overlay and existing AC layer is crucial for the pavement …

Two Essays On Executive Compensation, Michael Abrokwah

Open Access Theses & Dissertations

This doctoral dissertation examines the effect of an exogenous event on Executive compensation and the relationship between executive compensation and earnings management undertaken by the firm.

My first essay presents evidence that natural disasters have an effect on CEO compensation. Our main findings are that option compensation is lower for CEOs in counties where a natural disaster occurred. Furthermore, in the year of the disaster, stock compensation is higher among CEOs in natural disaster counties when compared to those in non-disaster counties. When considering liquidity, option compensation levels are lower for firms with below average liquidity levels but stock compensation …

Burning, Nicolas Cooper

Open Access Theses & Dissertations

Burning is a book of poetry about occult magic, the Catholic eye, the mind jewel, and the color of my skin under the summer sun. It is about my meditations in the shade under desert trees and the visions I had there about access, love, and social class. Burning is the flaming desire inside of me for success and recognition, and yet at the same time homage to the Zen Buddhist precepts of non-attachment and acceptance. It is my thirsting for the lost américa's touch somewhere between endless sands and yellow-painted concrete, about my parallel aspirations for poetic duende and …

Ingo Websites, Image Circulation, And Visual Representations Of Development In African Countries: Exploring Local Perceptions, Ruby Pappoe

Open Access Theses & Dissertations

This project critically examines the visual and digital representations of African countries on Savethechildren.org, Oxfam.org, Mamahope.org, and Waterislife.com, using Ethnographic Content Analysis (ECA), Critical Discourse Analysis (CDA), and focus group interviews. Grounded in interdisciplinary conversations within rhetoric and composition, intercultural technical communication, postcolonial studies, and development studies, this project reveals how inequalities of the past continue to exist in both visual and digital forms on international NGO websites. It shows that although these organizations seek to promote development and social change in low- and middle-income communities in Africa, the online content they use not only engender but keep in constant …

The Scramble For Texas: European Diplomacy And Imperial Contest In The Republic Of Texas, 1835-1846, Penelope Lea Jacobus

Open Access Theses & Dissertations

The story that this Dissertation analyses is the attempted European penetration of the North American borderlands during the independence of the Texas Republic. It will analyse how the independence of Texas ties into new forms of imperialism exercised by Europeans and U.S.-Americans during the first half of the nineteenth century, a time when shifting ideas about freedom and coercion, international law and rights, civilisation, nationhood, and trade redefined imperial possibilities. Imperialism in the nineteenth century had to be increasingly compatible with ideas of freedom and justice, such as free trade, free labour and the use of fair legal tenets in …

Laplacian Spectra Of Kneser-Like Bipartite Graphs, Cesar Iram Vazquez

Open Access Theses & Dissertations

Given a,b ∈N such that a > b we define a Kneser-like bipartite graph G(a,b), whose two bipartite sets of vertices represent the a-subsets and b-subsets of S = {1,...,a + b + 1}, and whose edges are pairs of vertices X and Y such that X ∩Y = ∅. We prove that the eigenvalues of the Laplacian matrix of graphs G(a,1) are all nonnegative integers. In fact, we describe these eigenvalues, and their respective multiplicities.

Density Functional Calculations On Single Molecular (1d) And Van Der Waals Bi -Layered (2d) Magnets., Md Shamsul Alam

Open Access Theses & Dissertations

Low-dimensional magnetic materials show novel properties that is not seen in bulk magnets. The weak interactions such as spin-orbit interactions, electron correlation, van der Waals interaction in case magnetic bi-layers, play an important role in determining the properties of the system. Using density functional theory, we computationally investigated two categories of magnetic material- 1: Single Molecular Magnets (SMM) 2: Van der Waals layered Cr-Halide magnets. We used different classes of density functionals to examine the spin ordering and magnetic anisotropy barriers in several single molecule magnets - Mn12, Co4, Ni4, V15. We find that the magnetic anisotropy barrier significantly depends …

Associations Of Traffic Related Air Pollution With Physical Activity And Cardiorespiratory Health Outcomes In At-Risk Populations From El Paso, Texas, Juan Aguilera

Open Access Theses & Dissertations

Exposure to air pollution from traffic-related emissions is a considerable preventable cause of respiratory and cardiovascular diseases. However, the impacts on at-risk populations, such as children with asthma and low-income residents, are yet to be fully understood in the border city of El Paso, TX. This dissertation focused on the most common traffic-related pollutants which include particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), and ozone (O3). The research described in this work provides an overview of air pollution measurements and shares insights from three different studies in our region.

People with asthma are more likely adversely affected by traffic …

Synthesis Of Nanotemplated, Glucose-Derived Adsorbents For The Removal Of Organic And Inorganic Pollutants From Water, Luis Alfonso Barrera

Open Access Theses & Dissertations

With an ever-present rise in population, along with an increase in industrial and manufacturing plants, contamination of potable water has become a global concern. While water treatment facilities exist which can help with the purification of water from bacterial and organic contaminants, these facilities are expensive to set in place and maintain. Therefore, in impoverished areas, point of use (POU) purification systems are often preferred, such as filters made from activated carbon. These filters are inexpensive and relatively easy to install and use. However, while activated carbons generally display excellent adsorption capabilities towards organic contaminants, their adsorption towards inorganic pollutants …

Toward Automated Region Detection & Parcellation Of Rat Brain Tissue Images, Alexandro Arnal

Open Access Theses & Dissertations

People who analyze images of biological tissue often rely on segmentation of structures as a preliminary step. In particular, laboratories studying the rat brain manually delineate brain regions to position scientific findings on a brain atlas to propose hypotheses about the rat brain, and ultimately, the human brain. Our work intersects with the preliminary step of delineating regions in images of brain tissue via computational methods.

We investigate pixel-wise classification or segmentation of brain regions using ten histological images of brain tissue sections stained for Nissl substance, and two deep learning models: U-Net and Tile2Vec. Our goal is to assess …

A Performance-Based Analysis Of Balanced Mix Designs, Elias Aaron Castillo

Open Access Theses & Dissertations

The Superpave design procedure was established to provide a more representative design methodology and to minimize typical pavement distresses such as fatigue cracking and permanent deformation. This Superpave design methodology was developed on the premise that the voids in mineral aggregate can evaluate the quality and constructability of asphalt mixture during the design and production phases. With the increased use of recycled materials, recycling agents, modified binders and warm mix asphalt additives, several highway agencies including the Texas Department of Transportation (TxDOT), have investigated whether the Superpave volumetric-based design method is enough to ensure appropriate performance of the final product. …

Comparing Predictive Performance Of Statistical Learning Models On Medical Data, Francis Biney

Open Access Theses & Dissertations

This work investigates the predictive performance of 10 Machine learning models on three medical data including Breast cancer, Heart disease and Prostate cancer. Furthermore, we use the models to identify risk factors that contribute significantly to these diseases.

The models considered include; Logistic regression with L1 and L_2 penalties, Principal component logistic regression(PCR-LR), Partial least squares logistic regression(PLS-LR), Multivariate adaptive regression splines(MARS), Support vector machine with Radial Basis Kernel (SVM-RBK), Random Forest(RF), Gradient Boosting Machines(GBM), Elastic Net (Enet) and Feedforward Neural Network(FFNN). The models were grouped according to their similarities and learning style; i) Linear regularized models: LR-Lasso, LR-Ridge and …

The Influence Of Over-Ground Versus Treadmill Walking On Gait Mechanics In Children With Autism Spectrum Disorder, Emily Ann Chavez

Open Access Theses & Dissertations

Treadmill (TM) walking may be a way to combat obesity and socio-behavioral barriers associated with children with Autism Spectrum disorder (ASD), though tripping-risk has not yet been assessed for this population through use of spatial-temporal gait analysis. The aim of this project/study was to examine spatial-temporal walking mechanics and lower extremity tripping descriptors between over ground (OG) and TM gait conditions in children with ASD compared to children with neurotypical development (NT). Kinematics data were obtained through tridimensional motion analysis where participants, 10 children with ASD and 9 age- and sexmatched NT controls, were outfitted with retroreflective markers on their …

Method Development For The Analysis Of Fatty Acids In Adipose Tissue Using Stir Bar Sorptive Extraction Coupled With Gas Chromatography-Mass Spectrometry, Angela Marisol Encerrado Manriquez

Open Access Theses & Dissertations

The project was aimed to develop an easy and sensitive analytical tool to study the role of fatty acids (FAs) profile in periprostatic adipose tissue (PPAT) and prostate cancer (PCa). PCa is the second leading cause of cancer-related death among American men. Although obesity has been mostly ruled out by many researchers as a risk factor for developing PCa, it has shown to be associated with PCa metastasis and progression. Periprostatic adipose tissue, which was present on 48% of prostatic surfaces, has been reported to act as energy sources for facilitating a positive microenvironment for PCa tumor progression. To understand …

Ketamine Pre-Exposure Does Not Influence Later-Life Responses To Reward-Related Stimuli In Female C57bl/6 Mice, Israel Garcia

Open Access Theses & Dissertations

Preclinical work indicates that exposure to traditional antidepressant medications, in adolescent and adult female subjects, alters reward-related behavior later in life. In recent years, the anesthetic ketamine (KET), now used as a fast-acting antidepressant, has shown promising therapeutic efficacy for the management of depression. However, the potential long-term behavioral consequences of KET exposure across development have not been thoroughly assessed. Thus, to address this issue, we examined if KET exposure, during adolescence or early adulthood, results in enduring alterations in responsivity to the rewarding properties of sucrose and cocaine later in life. Specifically, female C57BL/6 mice were randomly assigned to …

Cellular Response Of Metallic Materials And Microstructure Entropy Guided Understanding Of Strength In Biomedical Austenitic Stainless Steels, Na Gong

Open Access Theses & Dissertations

Austenitic stainless steels and cobalt-chrome alloys are used to fabricate biomedical devices with good mechanical strength, excellent wear and corrosion resistance. Cellular activity of Zr-modified Co-Cr-Mo alloys and osteoblast functions on Cu-containing and Cu-free austenitic stainless steel were studied. Experiments on the influence of Zr addition to Co-Cr-Mo alloys and Cu-containing austenitic stainless steel clearly demonstrated that cell adhesion, proliferation and cell-substrate interactions were favorably modulated in the presence of Zr and Cu. Additionally, stronger vinculin focal adhesion contact and signals associated with actin stress fibers together with extracellular matrix protein, fibronectin, were observed. Furthermore, comparative studies on the effect …

El Clima En Casas Norteñas, David Hiriart

Open Access Theses & Dissertations

A novel

Some Fermi-Lowdin Orbital Self-Interaction Correction Studies On Atomic Systems, Christopher Alexis Ibarra

Open Access Theses & Dissertations

Density Function Theory (DFT) is a popular quantum chemistry calculation method with many appeals but also deficiencies. Many modification and additions to the method have been made over the years, such as self-interaction corrections and new density functional approximations. We review here the theoretical background needed for a basic understanding of quantum chemistry calculations. In addition, we present the quantum chemistry calculation method used in this paper called Fermi-Lowdin Self-Interaction Correction (FLOSIC), including the base code it was implemented on, the Naval Research Laboratory Molecular Orbital Library (NRLMOL) Code, and the resulting modified code simply called FLOSIC. Furthermore, we explore …

A Probabilistic Creep Constitutive Model For Creep Deformation, Damage, And Rupture, Md Abir Hossain

Open Access Theses & Dissertations

The structural analysis of Industrial Gas Turbine (IGT), Aeroengine, Gen IV nuclear components under in-service conditions at various stress and temperature are susceptible to time-dependent creep deformation and creep induced failure. Such failure phenomena are exacerbated by the randomness in material properties, oscillating loading conditions, and other sources of uncertainty. The demand for physically based probabilistic creep modeling is highly sought by alloy designers. The objective of this study is to develop and validate a probabilistic creep-damage model incorporating multi-sources of uncertainty to replace the traditional deterministic and empirical decision-based modeling. In this study, the deterministic Sine-hyperbolic (Sinh) creep-damage model …

Mathematical Modeling Of Microemulsification Processes, Numerical Simulations And Applications To Drug Delivery, Ogochukwu Nneka Ifeacho

Open Access Theses & Dissertations

Microemulsion systems are a great pharmaceutical tool for the delivery of formulations containing multiple hydrophilic and hydrophobic ingredients of varying physicochemical properties. These systems are gaining popularity because of its long shelf life, improved drug solubilisation capacity, easy preparation and improvement of bioavailability. Despite the advantages associated with the use of microemulsion systems in pharmaceutical industries, the major challenge impeding their use has been and continues to be the lack of understanding of these systems.

Microemulsions can be mathematically modeled by an initial boundary value problem involving a sixth order nonlinear time dependent equation. In this Thesis, we present a …