Digital Commons Network^™

Mitigating Calcium Oxychloride Damage In Cementitious Paste And Concrete Utilizing Supplementary Cementitious Materials, Casey Jones

Graduate Theses and Dissertations

It is understood among engineers in the United States (U.S.) that improvement is needed throughout the transportation infrastructure. In the 2021 Infrastructure Report Card produced by the American Society of Civil Engineers, the roadways of this nation merit a D. This leaves room for improvement in order to provide durable pavements throughout this nation. Areas with significant winter weather may have exacerbated effects in decreased roadway longevity due to freezing/thawing cycles and the use of chemical deicers to mitigate gelid roadway conditions. Much research focuses on surface scaling and reinforcement corrosion using these materials; however, joint deterioration, due to chemical …

Centropoly: The Structure Of Educational Failures In The U.S., Martha Bradley-Dorsey

Graduate Theses and Dissertations

How did a country birthed in individual liberty and voluntary associations create just the opposite in its inflexible, layered, government-controlled public education system? Here, using public choice theory, I explain how near-sighted and unrelated reforms, often based in private motives, gave us what I call the public education centropoly – a hybrid government organization consisting of a set of monopolies layered beneath two additional government levels that especially fails disadvantaged students.

After defending the use of public choice theory (Chapter 1) and summarizing the U.S. public education system formation (Chapter 2), in Chapter 3 I examine the Elementary and Secondary …

Machine Learning & Big Data Analyses For Wildfire & Air Pollution Incorporating Gis & Google Earth Engine, Abdullah Al Saim

Graduate Theses and Dissertations

The climatic condition, the vegetation type, and the landscape of the United States have made it susceptible to wildfires. This research is divided into two parts based on the analysis of two different aspects of wildfires of two distinct regions. The first part of the study investigates the wildfire susceptibility in Arkansas. Arkansas is a natural state, and it is heavily dependent on its forest and agricultural resources. During the last 30 years, more than 1,000 wildfires occurred in Arkansas and caused more than 10,000 acres of burned areas. Therefore, identifying wildfire-susceptible areas is crucial for ensuring sustainable forest and …

Child-Centered Play Therapy’S Impact On Externalized Behaviors Of Children Who Have Experienced Trauma: A Single-Case Research Design, Timothy "T.J." Schoonover

Graduate Theses and Dissertations

Adverse childhood experiences (ACEs) are defined as exposure to emotional abuse, physical abuse, sexual abuse, emotional neglect, physical neglect, loss of a parent, domestic violence, family member with addiction, family member with depression or mental illness, and family member incarcerated (Felitti et al., 1998). ACEs have been studied for many years and have shown to have long term negative health and social-emotional outcomes and costs the world over $1 trillion a year (Bellis et al., 2019; Felitti et al., 1998; Hughes et al., 2017). Due to the emotional, physical, and dollar amount cost to not addressing the impact of ACEs …

On Human Rights And Structural Justice, Robert Howard

Graduate Theses and Dissertations

The rights literature is full of accounts of rights, and each captures important aspects of the nature and function of rights. But none of the leading theories offers a comprehensive account of the nature and function of rights that both stands up under the pressure of counterexamples and can buck accusations of internal inconsistency.

In this paper I embrace much of Nicholas Wolterstorff's work on justice and the relation of human rights to worth, and I propose changes to his account in order to strengthen it. I evoke the works of Johan Galtung, Richard Rubenstein, and Elizabeth Anderson in order …

Evaluating The Efficiency Of Markov Chain Monte Carlo Algorithms, Thuy Scanlon

Graduate Theses and Dissertations

Markov chain Monte Carlo (MCMC) is a simulation technique that produces a Markov chain designed to converge to a stationary distribution. In Bayesian statistics, MCMC is used to obtain samples from a posterior distribution for inference. To ensure the accuracy of estimates using MCMC samples, the convergence to the stationary distribution of an MCMC algorithm has to be checked. As computation time is a resource, optimizing the efficiency of an MCMC algorithm in terms of effective sample size (ESS) per time unit is an important goal for statisticians. In this paper, we use simulation studies to demonstrate how the Gibbs …

Signal Processing And Data Analysis For Real-Time Intermodal Freight Classification Through A Multimodal Sensor System., Enrique J. Sanchez Headley

Graduate Theses and Dissertations

Identifying freight patterns in transit is a common need among commercial and municipal entities. For example, the allocation of resources among Departments of Transportation is often predicated on an understanding of freight patterns along major highways. There exist multiple sensor systems to detect and count vehicles at areas of interest. Many of these sensors are limited in their ability to detect more specific features of vehicles in traffic or are unable to perform well in adverse weather conditions. Despite this limitation, to date there is little comparative analysis among Laser Imaging and Detection and Ranging (LIDAR) sensors for freight detection …

The Application Of Complex Systems Science To Political Philosophy, Benjamin Nicholas House

Graduate Theses and Dissertations

Although complex systems science is relevant to problems of political philosophy, the intersection of these two disciplines has not been studied in depth. Complex systems are made up of multiple interdependent parts whose interactions create emergent properties. This interdependence makes these systems “fat-tailed”: low-probability events can have a major impact on the system. Complex systems engineers have formulated a series of rules of thumb for approximating an “evolutionary” environment. Contemporary human civilization is a complex system; because of this, governments need to become adaptable and approximate the evolutionary environment by fostering policy innovation while at the same time promoting mechanisms …

Understanding The Importance Of Ambition In The Workplace, Jeff Bean

Graduate Theses and Dissertations

Though a common term, ambition is a multifaceted concept that is vastly under researched despite it being labeled necessary for success in the workplace. Of even greater irony is that several sources indicate a significant majority of the reason that employees leave organizations is due to a perceived lack of career development or opportunity, a problem that speaks directly to talent management practices. In light the costly nature of this problem and the presence of sophisticated talent management professionals in large and medium-sized organizations which comprise half or more of the workforce, it causes one to question the assumptions that …

The Effect Of A Mindfulness-Based Intervention On Attention And Cognitive Control As A Function Of Smartphone Notifications., Joshua D. Upshaw

Graduate Theses and Dissertations

Barriers to accessing mobile technology, particularly smartphones, have decreased substantially since the iPhone’s release in 2007, resulting in increased ownership and usage across all ages, genders, and races. Despite their ubiquity in our society, relatively little empirical work has investigated the influence of smartphones on our higher order executive functioning. Prior work has linked smartphone use with impaired cognitive control during cognitively demanding tasks, especially in heavier smartphone users. The goals of the current study were twofold. First, the study aimed to examine the effects of smartphone notifications on cognitive control and attention. And second, to determine the effects of …

Essays On Spatial Econometrics Application In Study Of Conflict And Economic Activity, Ahmed Sadek Yousuf

Graduate Theses and Dissertations

Spatial interaction and the locational structure between observations as well as availability of satellite derived data has meant a richer and more exhaustive exploration of topics relevant in development topics, particularly in areas of subnational economic activity and conflict. This research leverages thus spatial econometric techniques to dynamically decompose impacts from socio-economic determinants on conflict incidence (with setting in Sub-Saharan Africa). Later I also present a statistical framework (based on extension of Henderson’s approach (2012)) to augment official income figures at district / county level with multiple satellite derived signals, with specific context given to developing countries.

In the first …

What Makes A Lie? A Novel Study Investigating The Difference Between Deliberate Lies And Honest Mistakes, Andrew Christopher Provenzano

Graduate Theses and Dissertations

Previous research on lie detection suggests that people use cues to deception to make a true-false judgment about a statement. However, no prior research has investigated what factors cause others to classify known false statements as an intentional lie or an "honest" mistake. This dissertation reports two studies that sought to answer this question. Experiment 1 consisted of a diary study where participants reported false statements and then described their reason for classifying the statements as a deliberate lie or honest mistake. In Experiment 2, participants completed a semi-structured interview where they described various false statements and why they classified …

Medical Error Disclosure: A Content Analysis Of State Legislation, Teresa Kathleen Sparks

Graduate Theses and Dissertations

Medical error is a public health problem in the United States (U.S.), causing approximately 250,000 hospital deaths per year. Health care leaders and policy-makers have identified medical error disclosure as one of many viable evidence-based solutions to address the problem of medical error – leading to increased transparency in health care, improved patient outcomes, potential medical malpractice cost reduction, and decreased health care provider distress and turnover. Unfortunately, health care providers are often hesitant to practice disclosure and are not required to do so in most U.S. jurisdictions. A qualitative inquiry using content analysis was conducted to understand the language …

"A Rabble Rouser All The Time": Jim Johnson And The Politics Of Massive Resistance In Arkansas, Marie Cathryn Totten

Graduate Theses and Dissertations

James D. “Jim” Johnson was an Arkansas politician best known for his racism, commitment to segregation, and failed gubernatorial campaigns. Johnson makes appearances in some of Arkansas’ most notorious political moments in the 20th century. He campaigned for the Dixiecrats in 1948, led the state’s first major protest against integration in 1955, pushed Governor Orval Faubus to become a segregationist in 1956, and lost multiple elections in the 1960s. Although not victorious at the polls, Johnson had a tremendous influence on Arkansas politics in the middle of the 20th century. He made integration a viable political issue in the state …

Direct Torque Control For Silicon Carbide Motor Drives, Mohammad Hazzaz Mahmud

Graduate Theses and Dissertations

Direct torque control (DTC) is an extensively used control method for motor drives due to its unique advantages, e.g., the fast dynamic response and the robustness against motor parameters variations, uncertainties, and external disturbances. Using higher switching frequency is generally required by DTC to reduce the torque ripples and decrease stator current total harmonic distortion (THD), which however can lower the drive efficiency. Through the use of the emerging silicon carbide (SiC) devices, which have lower switching losses compared to their silicon counterparts, it is feasible to achieve high efficiency and low torque ripple simultaneously for DTC drives.

To overcome …

Negative Urgency's Influence On State-Level, Emotion-Based Changes In Alcohol-Related Cognitions, Noah Wolkowicz

Graduate Theses and Dissertations

This project expanded on the Acquired Preparedness Model of Risk (APMR) by examining how Negative Urgency (NU), the tendency to act rashly in negative emotional states, affects emotion-based changes in alcohol cognitions to produce risk for alcohol use. The APMR prioritizes the role of outcome expectancies as the means through which traits such as NU, convey alcohol use risk. However, this model treats these cognitions as static and often fails to assess their valence; further, alcohol-cognitions fluctuate in response to negative emotions and may become more salient during these states. Therefore, this study examined: 1) how NU impacts negative emotion-based, …

Computational Modeling Of Black Phosphorus Terahertz Photoconductive Antennas Using Comsol Multiphysics With Experimental Comparison Against A Commercial Lt-Gaas Emitter, Jose Isaac Santos Batista

Graduate Theses and Dissertations

This thesis presents computational models of terahertz (THz) photoconductive antenna (PCA) emitter using COMSOL Multiphysics commercial package. A comparison of the computer simulated radiated THz signal against that of an experimentally measured signal of commercial reference LT-GaAs emitter is presented. The two-dimensional model (2D) aimed at calculating the photoconductivity of a black phosphorus (BP) PCA at two laser wavelengths of 780 nm and 1560 nm. The 2D model was applied to the BP PCA emitter and the LT-GaAs devices to compare their simulated performance in terms of the photocurrent and radiated THz signal pulse. The results showed better performance of …

Discipline Disproportionality Of Black Students With Disabilities: Principals' Perspectives, Wanda L. Van Dyke

Graduate Theses and Dissertations

The purpose of this study is to examine the problem of practice found in discipline disproportionality of Black students with disabilities in an urban school district with a majority Black student and teacher population. Through personal interviews with building level administrators, data was gained to determine common themes that impact discipline disproportionality of Black students with disabilities. A qualitative inquiry approach, in the form of a case study was used to determine principals’ perspectives about factors that may impact discipline disproportionality. Student disciplinary records were examined to verify disproportionality and investigate patterns and categories related to students with and without …

Of Biodiversity, Boundaries, And Distribution: The Myxomycetes Of The Philippines And Beyond, Sittie Aisha Bustamante Macabago

Graduate Theses and Dissertations

This dissertation contains a compilation of independently performed studies primarily focusing on the myxomycetes (plasmodial slime molds) from the Philippines and integrating local and worldwide data to demonstrate regional and global trends. The major themes include the following: (I) a review of the diverse group of spore-producing amoeboid protists, including the myxomycetes; (II-IV) diversity assessments in three different groups of islands in the Philippine archipelago; (V) mapping the myxomycetes found in the Philippines for databasing and analyzing the geocoded data; (VI) a study on regional boundaries, including the Philippines, using myxomycete species composition; and, (VII) creating a global species distribution …

An Experimental Study Of Evaporites On Titan: Implications For Lake Composition And Future Missions, Ellen Czaplinski

Graduate Theses and Dissertations

Titan is the only other planetary body in the solar system with liquid on the surface. With a surface temperature and pressure of 89 – 94 K and 1.5 bar (N2), respectively, Titan’s lakes are comprised of liquid hydrocarbons, predominantly methane and ethane. Over time, Titan’s lakes may evaporate, leaving behind residual deposits (evaporites). The evaporation processes and composition of the evaporites is poorly understood. I address these outstanding questions by experimentally investigating the physical and spectral properties of evaporites at Titan surface conditions using an experimental chamber.

Chapter 1 addresses the formation of ethylene evaporites. Ethylene evaporites form more …

Naturalistic Decision Making In First Sales Calls: A Narrative Study Of Experienced Technical Sales Professionals, Douglas Williams

Graduate Theses and Dissertations

The first conversation between business-to-business sellers and new customers comes with the potential for both opportunity and risk. Sellers spend substantial effort gaining the right to engage in a first call with a potential customer. This study fills a gap in the literature by exploring the role of Naturalistic Decision Making (NDM) and how it impacts the way experienced technology sales professionals navigate first conversations with new customers. NDM explores how experienced professionals make decisions in high-stakes, real world situations that are ambiguous, time-pressured, and have poorly defined goals. While NDM studies have been performed in other professional disciplines, none …

Impact Of Covid-19 On The Severe Acute Malnutrition Admissions Among Children Under 5 Years Of Age Seeking Nutrition Services In Afghanistan, Sahar Sayedy

Graduate Theses and Dissertations

The purpose of the study was to assess the impact of COVID-19 on the number of admissions of severe acute malnutrition among children under 5 years of age seeking nutrition services in Afghanistan especially in the provinces where the prevalence of COVID-19 was high, for the period of February – September 2020. The study used comparison and analysis of secondary datasets of the Integrated Management of Acute Malnutrition – a national program for detection and management of moderate and severe acute malnutrition in the country.

This study analyzed the association between COVID-19 cases and severe acute malnutrition (SAM) admissions of …

Privacy-Preserving Cloud-Assisted Data Analytics, Wei Bao

Graduate Theses and Dissertations

Nowadays industries are collecting a massive and exponentially growing amount of data that can be utilized to extract useful insights for improving various aspects of our life. Data analytics (e.g., via the use of machine learning) has been extensively applied to make important decisions in various real world applications. However, it is challenging for resource-limited clients to analyze their data in an efficient way when its scale is large. Additionally, the data resources are increasingly distributed among different owners. Nonetheless, users' data may contain private information that needs to be protected.

Cloud computing has become more and more popular in …

Structural And Electronic Properties Of Few-Layer Monochalcogenides, Brandon Joel Miller

Graduate Theses and Dissertations

This work discusses a new class of materials with novel properties that have only recently begun being studied. These materials are two-dimensional group IV-VI monochalcogenides, so named because they are formed from group IV (carbon group) and group VI (chalcogens) elements. These materials display several interesting physical properties such as ferroelasticity and ferroelectricity, and the contents within Chapters Two, Three, and Four concern a collaborative effort between theory and experiment between our group at the University of Arkansas and Dr. Kai Chang at the Max Planck Institute of Microstructure Physics in Halle, Germany in studying these properties. This thesis is …

Design And Validation Of A High-Power, High Density All Silicon Carbide Three-Level Inverter, Zhongjing Wang

Graduate Theses and Dissertations

Transportation electrification is clearly the road toward the future. Compared to internal combustion engine, the electrified vehicle has less carbon-dioxide emission, less maintenance costs and less operation costs. It also offers higher efficiency and safety margin. More importantly, it relieves human’s dependence on conventional fossil energy. In the electrification progress, the revolution of electric traction drive systems is one of the most important milestone. The traction system should keep high efficiency to avoid performance reduction. Moreover, the motor drive should be designed within limited space without sacrificing output power rating. Based on the road map from US Drive Electrical and …

A Multicase Study Exploring The Motivation Of Support Staff In The Office Of The Registrar, April M. Martin

Graduate Theses and Dissertations

Although a large body of research exists within higher education that focuses on factors related to faculty motivation and student motivation, there is limited research concentrated on the motivation of college and university administrative staff. This study examined how job duties, work processes, elements of the work environment, and leadership styles are related to employee motivation, specifically the motivation of front-line support staff who work in the Office of the Registrar. Additionally, I aimed to identify any disconnect between what support staff need and want from supervisors in the Office of the Registrar pertaining to motivation and supervisors’ behavior to …

The 'I' In First-Person Thought And What Is Meant By Self-Knowledge, Aaron Morris

Graduate Theses and Dissertations

There has been a great deal of disagreement over what exactly it is that is being referenced by the first-person pronoun, ‘I.’ Immanuel Kant believed the ‘I’ associated with a thinking subject is just a formal representation of the substantially existing subject. This raises the question about whether or not ‘I’ is actually a referring expression? In this paper I explore two accounts from both sides of the debate which opens up a dialectical space for determining a positive answer for this question. On the one hand, ‘I’ is said to be a referring term for the speaker or utterer …

High Temperature Degradation In Gan-Based Hall Effect Sensors, Alexis Anne Krone

Graduate Theses and Dissertations

This research focuses on understanding the effects of accelerated aging through temperature and environment on novel gallium nitride-based Hall effect magnetic field sensors and determining device reliability under electric vehicle operating conditions. The device reliability was modeled using accelerated aging for the temperatures of 200 °C, 350 °C, 450 °C, and 600 °C under various time steps unique to each temperature and either air, which is identical to operating circumstances, or argon, which would model the hermetic packaging environment. Using a high temperature furnace and oven, devices underwent high temperature storage tests at a chosen temperature and time step. Afterwards, …

Evaluating The Economics Of Gluten-Free Households, Keia Mornys Alicia Jones

Graduate Theses and Dissertations

Over the past two decades, the diagnoses of gluten allergies and celiac disease has increased significantly. Although there has been no development of a cure for either ailment, these conditions can be managed by the elimination of glutenous foods from a person’s diet. In previous studies, the financial cost of replacing or excluding glutenous foods was higher than the financial cost of diets that do not exclude gluten. The objective of this study is to examine the differences in the economic feasibility of a conventional diet in comparison to a gluten-free diet. Using a sample of foods and prices from …

Characterization Of Iron-Sulfur Cluster Biogenesis In Methanogenic Archaea, Thomas Modlin Deere

Graduate Theses and Dissertations

Iron-sulfur (Fe-S) clusters are among the oldest cofactors on the planet, used by proteins in almost all forms of life on Earth to carry out processes ranging from energy transfer to DNA replication. Among the organisms believed to use these Fe-S proteins more extensively than almost any others are the methanogens, an ancient lineage of archaeal microbes that produce methane as a required product of their metabolism. Methane, the primary component of commercial natural gas, is both a potent greenhouse gas and an important fossil fuel. It can also be renewably produced as a biofuel. Biogenic methane is almost entirely …