Digital Commons Network^™

Real Time Adaptive Control Of A Pid Via Genetic Algorithm Machine Learning Systems, Cemre Tas

Graduate Theses and Dissertations

The most common control method that is utilized by all industries across the world is the proportional-integrative-derivative controller (PID) due the relatively low cost and complexity of the system. However, there are draw-backs with PIDs, it is not adaptative to a changing system, so it works on nominal systems, and it starts breaking down when a system begins to have a non-linear response. The method chosen to overcome both is the utilization of machine learning with the use of genetic algorithms.

This method allows any PID system to be capable of adapting in real-time, while not adding significant additional cost …

Quantifying The Effects Of Urbanization On Stream Nutrient Loads And Decomposition, Caroline Anscombe

Graduate Theses and Dissertations

Urban stream syndrome (USS) refers to the common symptoms of degradation in urban streams globally. Two symptoms of USS are increased nutrient and salt concentrations in streams, affecting ecosystem structure and function. Excess nutrients negatively impact freshwater ecosystems, placing downstream habitats at risk of eutrophication and harmful algal blooms. Excess salt runoff, derived from road salt application, is toxic to freshwater organisms and affects leaf litter decomposition, the base of aquatic food webs. Here, I aimed to quantify the effects of nutrient pollution and salinization on urban water quality and ecosystem function. Despite the widespread consequences of nutrient pollution, most …

Utility Of John Deere's See & Spray Ultimate In Southern U.S. Row Crops, Tristen Avent

Graduate Theses and Dissertations

Row crop producers across the southern United States are observing a boom in technological advancement to improve operational efficiency. Additionally, environmental concerns and reduced profit margins drive the adoption of targeted pesticide application technologies like the John Deere See & Spray. This technology is relatively new, introduced in 2022, and producers need more insight into the shortcomings, potential herbicide savings, and the economic benefits of adoption. Since 2021, research has been conducted in Keiser, AR, with additional collaborative projects in Mississippi, North Carolina, Indiana, and Illinois. Five different objectives were addressed in this research: 1) to determine the impact of …

Crispr-Cas9 Integration Of Salmon Elovl2 In Zebrafish Enhances Lc-Pufa Biosynthesis And Growth Across Diets, Waleed Sami J. Al-Bachry

Graduate Theses and Dissertations

Fish are a rich source of EPA and DHA, which are well-known long-chain polyunsaturated fatty acids (LC-PUFAs). The sustainable production of these essential fatty acids poses significant challenges, mainly due to our dependence on marine fish and certain nuts. CRISPR-Cas system was utilized to insert the elongation of long-chain fatty acids-like2 (Elovl2) gene from Salmo salar into Danio rerio. Elovl2 was introduced at 10-15-minute post-fertilization, and successful integration confirmed by PCR genotyping, sequencing and expression of EGFP. Approximately 67% of injected embryos successfully exhibited EGFP and sequence results verified the gene integration of Salmo salar Elovl2 at the first start …

Nonparametric Methods For Bayesian Community Detection In Complex Networks, Kedran Young

Graduate Theses and Dissertations

Network analysis is becoming an increasingly popular interdisciplinary area of study, with emerging interest in fields like sociology, biology, economics, and ecology. Within the niche of network analysis, capturing the community structure of a network is one important achievement that many statisticians have been working toward over recent decades. The most popular modeling technique for latent community detection is the Stochastic Block Model (SBM), which falls into the category of latent variable models and will serve as the baseline model throughout this thesis. SBM is widely regarded as the most effective community detection method as it detects latent community membership …

Gender, Politics, And Power: How Women Presidential Candidates Are Framed By News Narratives, Victoria Hernandez

Graduate Theses and Dissertations

The aim of this study was to look at the coverage of the presidential campaigns of Hillary Clinton in 2016 and Kamala Harris in 2024 during the Democratic National Convention, and analyze the differences in regard to gender, race, and political bias. The examination of these news narratives helps explore a question of whether journalists report with bias when covering politics. The researcher analyzed 11 published pieces from five mainstream media outlets. Findings of the study show that bias is unavoidable even when a journalist strives for objectivity which does not exist in newsrooms across the political spectrum. The findings …

Investigating Evolution Through The Lens Of Ai-Driven Protein Exploration And Phylogenetic Modeling, Mataya Duncan

Graduate Theses and Dissertations

Recent advances in computational biology, artificial intelligence, and sequencing technologies have enabled new perspectives for addressing longstanding questions in evolutionary biology. Increased computational power has made large-scale simulations feasible for investigating diverse aspects of evolutionary and phylogenetic modeling. Similarly, deep learning algorithms now allow for the prediction of reasonably accurate tertiary protein structures, unlocking the potential for investigating diversity and evolution of protein structure across a broad range of organisms. This thesis presents two studies that target different aspects of evolutionary inference from unique perspectives. Yet, the share an overarching goal of presenting new perspectives on the evolutionary basis of …

Experiences Of Black Senior Housing Officers At Predominantly White Institutions In The South, Christian M. Robinson

Graduate Theses and Dissertations

This study examines the lived experiences of Black Senior Housing Officers (SHOs) at predominantly white institutions (PWIs) in the Southern United States. This narrative inquiry study interviewed nine Black SHOs who worked at Southern PWIs. The findings of this study are that participants emphasized that racism remains a significant and present concern at their institutions as informed by Critical Race Theory (CRT). One participant stressed the importance of Black professionals fully understanding the historical context of the South when working in higher education, noting that this knowledge was critical for survival and success. Many participants also described how effective mentorship …

Multi-Decadal Land Change Dynamics In Indonesia: Disentangling The Cycle Of Agricultural Land Conversions, Urbanization, And Deforestation, Wei Lun Tay

Graduate Theses and Dissertations

Land use and land cover change (LULCC) significantly impacts Earth’s environmental, climatic, and human systems, especially in tropical regions rich in natural resources and undergoing rapid development. This study examined the spatiotemporal dynamics of LULCC in Indonesia between 2003 and 2023 using remote sensing and geographic information systems/science (GISci) and explored knowledge gaps in agricultural land conversions and the impact of food security programs such as the Food Estate Program. This study employed the Moderate Resolution Imaging Spectroradiometer (MODIS) MCD12Q1 land cover data available through Google Earth Engine, and classified land cover changes into four dominant categories: forest land, mixed …

Variation In Stress Response Regulation Across Natural Isolates Of Saccharomyces Cerevisiae, Crystal Christine Crook

Graduate Theses and Dissertations

The stress response of Saccharomyces cerevisiae is a valuable area of study for understanding cellular adaptation mechanisms that govern survival in fluctuating environments. This dissertation investigates stress response regulation in yeast through the roles of Hog1 mitogen-activated protein kinase (MAPK) and the post-transcriptional regulator Mkt1, a key post-transcriptional regulator, in diverse wild yeast isolates. Hog1 is traditionally known for its central role in osmotic stress regulation in the high-osmolarity glycerol (HOG) pathway. This study expands the functional scope of Hog1 to include oxidative and ethanol-induced stress responses.

In parallel, we investigate post-transcriptional regulation of stress responses by the Mkt1 interactome, …

Elucidating The Mechanisms Of Collagenase H From Hathewaya (Clostridium) Histolytica In Collagen Degradation And Developing A Cross-Linked Platform For Efficient Capture And Release Of Adeno-Associated Virus Serotype 2 (Aav2), Adjoa Otubea Bonsu

Graduate Theses and Dissertations

In biological systems, Hathewaya (Clostridium) histolytica secretes collagenases that degrade structural collagen in host tissues and cause tissue necrosis. Despite their detrimental effects, these enzymes have significant therapeutic potential by effectively digesting various collagen subtypes to treat connective tissue disorders. The bacterium produces two homologous collagenases, ColG and ColH, with a catalytic module crucial for hydrolyzing collagen and binding domains, including collagen-binding domains (CBDs) and polycystic kidney disease-like domains (PKDs), for substrate interaction.

Although the crystal structure of the catalytic module of collagenase G (ColG) has been determined, shedding light on its chew-and-digest mechanism, the structure of collagenase H (ColH) …

Land Cover Effects On Stream Water Chemistry In The Upper Saline River Watershed, Brandy Everett

Graduate Theses and Dissertations

Non-point source (NPS) pollutants and the conversion of natural areas to anthropogenic uses are one of the most critical stressors on water quality. The Upper Saline River Watershed has seen an increase in anthropogenic land cover over the last two decades, leading it to be previously identified as a 319 NPS priority watershed in Arkansas. This study used publicly available data to assess the magnitude and trends of total nutrients (TN and TP) at both the watershed and site level scale. Results suggest a decrease of 2.6%/yr in TN concentrations and 1.5%/yr in TP concentrations at the watershed scale. While …

Advanced Numerical Techniques For Multiscale Simulations In Biofluid Dynamics, Justin Tamico Jack

Graduate Theses and Dissertations

The study of anisometric particle suspensions and congenital heart defects (CHDs) involve exploring complex phenomena within the biological sciences. The former subject dives into the phase behavior of liquid crystals (LCs), particularly the influence of the shape anisotropy of rod-like nanoparticles on phase transitions, through the implementation of statistical techniques involving molecular dynamics (MD). Conversely, the latter topic focuses on the assessment and management of severe congenital arterial stenoses, such as those found in Williams-Beuren syndrome (WS), through advanced multi-scale computational fluid dynamics (CFD) simulations. Both areas emphasize the importance of detailed analysis and the use of advanced numerical modeling …

Advancing Molecular Tools For The Study Of Rubus Viruses, Andrea Sierra-Mejia

Graduate Theses and Dissertations

Since blackberry yellow vein disease (BYVD) was first described, the blackberry virome has expanded significantly. BYVD is a complex disease associated with over ten viruses, yet the role of each virus in its etiology remains understudied. Studying the effect of each virus in disease development requires the identification of single infections; however, this task has been difficult for BYVD, with all field collected material over the past two decades consistently found infected by multiple viruses. Given the diversity of viruses associated with the disease and their different modes of transmission, obtaining pure virus cultures necessitate transmission of individual viruses via …

Effects Of Fast And Slow-Wilting Soybean Genotypes On Plant-Herbivore Interactions, Jessica Ayala

Graduate Theses and Dissertations

Soybean [Glycine max (L.) Merr.] is one of the most important food crops in the world due to its multiple uses in agriculture sector. A major limiting factor in soybean production system is drought stress, causing up to 80% reduction in yield. Due to climate change and associated rise in ambient temperatures, water scarcity is a major concern in crop production, and consequently researchers are turning to soybean accessions that demonstrate better water use efficiency (WUE) traits. However, field grown soybean is also under severe pressure from insect herbivores, often accounting for a 30% reduction in yield. Among these, …

Integrating Sustainability And Food Safety Through Quantitative Microbial Risk Assessment And Life Cycle Assessment Of Low-Moisture Foods, Jessica Bain

Graduate Theses and Dissertations

Food safety and sustainability are critical concerns in the food industry. However, these areas are often evaluated separately, leading to an incomplete understanding of the overall impact of food production on human health. This dissertation aims to integrate food safety with sustainability to provide a comprehensive assessment of the impact of low-moisture foods on human health, using the almond processing supply chain as a case study.

In addition to conducting life cycle assessments (LCA) of almond processing, wheat flour production, and dried apple processing, this dissertation aims to create a framework to bridge the gap between sustainability and food safety. …

Frogs On A Plain: Spatial Ecology Of Crawfish Frogs In Arkansas’ Remnant Prairies, Elliot T. Lassiter

Graduate Theses and Dissertations

The prairie peninsula was an expansive and important habitat that covered much of midwestern North America, from Canada to Arkansas, USA. But the prairie peninsula has shrunk by as much as 99% since 1830, and therefore, land acquisition and public/private partnerships are critical for the preservation of prairies and their associated species. In Arkansas, one species that benefits from protected prairies is the Crawfish Frog (Lithobates areolatus), which is currently declining precipitously throughout its range. Adult Crawfish Frogs spend most of their lives in terrestrial refugia (crayfish burrows), making them highly vulnerable to habitat loss and fragmentation, thereby …

Investigating The Perceived Invisibility Of The Black Woman Leader In Fortune 500 Companies: Understanding Career Pathways Based On Insight And Intersectionality, Shana Jones Yarberry

Graduate Theses and Dissertations

There is a gap in the literature when examining the intersectionality of race, gender, and class. There is additional distance when evaluating the impact each intersection has on the career development of Black Women (BW) in Fortune 500 companies. The purpose of this study was to use a qualitative approach to investigate how the intersectionality of race, gender, and class impact the career advancement of BW while also identifying perceived barriers, historical patterns of career movement, and organizational efforts to support the ascension of BW in senior leadership. The Systems Theory Framework of Career Development and Intersectionality Theory were examined …

Predicting Different Psychological Profiles Amongst Substance Users., Zach J. Gray

Graduate Theses and Dissertations

Substance use disorders (SUDs) are some of the most prevalent issues facing society. As SUDs are highly individualized in how they manifest, recent work has attempted to classify distinct profiles of drug users to better understand what factors put someone at risk for shifting from casual substance use to developing a substance use disorder (SUD). Common risk factors for SUD development include stressor exposure, difficulties with emotion regulation, personality, and risky decision-making. As many of the behaviors that constitute SUDs are exhibited prior to potential diagnosis, developing “profiles” that combine these traits and experiences could eventually predict SUDs. The current …

Synthesis And Process Optimization Of Cellulose Nanocrystals From Miscanthus X. Giganteus For Commercial Viability, Jaspreet Kaur

Graduate Theses and Dissertations

Cellulose nanocrystals (CNCs), derivatives of an abundant biopolymer, i.e., cellulose, are emerging as promising alternatives to petrochemical-based products due to their unique properties, including biodegradability, low toxicity, high strength, low density, large surface area and low coefficient of expansion. CNCs have diverse applications ranging from food packaging and textiles to drug delivery and medical implants, etc. Despite their potential, the widespread commercialization of CNCs faces significant hurdles owing to the high environmental burden and production costs. They are mainly driven by the commonly used source utilized for CNC synthesis i.e., wood and the intensive synthesis process i.e., requirement of …

Influence Of Hydrologic And Anthropogenic Disturbance On Stream Populations And Communities, Sarah Frances Sorensen

Graduate Theses and Dissertations

Disturbances occur when an external force modifies a habitat, destroying living space, removing food resources, or altering or destroying habitat structure. In lotic systems, a primary source of disturbance is hydrologic disturbance, including drought and flood. Hydrologic disturbances lead to increased mortality rates and dispersal out of disturbed habitats, causing population sizes to decrease and changes to community structures. More research is needed on how disturbances impact stream species and communities, as disturbances are predicted to become more intense with climate change. This dissertation aims to understand how disturbance influences streams at both the population and community level, through a …

Exploring The Capabilities Of Classifier-Free Guidance In Recommendation Tasks, Noah Buchanan

Graduate Theses and Dissertations

This thesis addresses the problem of recommending items to users based on their ratings of items through a diffusion recommender system. Regular recommender systems are already capable of efficient recommendation through conventional methods such as collaborative or content-based filtering. Diffusion is a new type of generative AI that aims to improve our previous AI's shortcomings in the generative domain, like Variational Autoencoders (VAEs) and Generative Adversarial Networks (GANs). We use diffusion to create a recommender system that mirrors the sequence users take when browsing and rating items. The current methods of recommendation with diffusion do not use the new innovation …

Multimodal Spectroscopy To Study Tumor Microenvironmental Changes In Vivo, April Mordi

Graduate Theses and Dissertations

Every year there are millions of new cancer diagnoses and deaths worldwide. While great strides have been made in technologies and drugs for cancer treatment, there is still a need to understand tumor response to therapy as many patients still endure treatment failure after completing their treatment regimen. Current clinical imaging techniques for detecting response to therapy are utilized weeks to months after the course of treatment, and present limitations to measuring response during treatment. Optical spectroscopy techniques can help meet this need to determine the response of tumors to treatment as it allows for near real-time in vivo characterization …

The Impact Of Wild Pigs (Sus Scrofa) On Avian Occupancy And Vegetation Structure, Kenneth Wilson

Graduate Theses and Dissertations

Invasive species, particularly wild pigs (Sus scrofa), pose a significant threat to native ecosystems through both direct and indirect impacts. Wild pigs are large-bodied omnivorous species that can consume a wide variety of plants and animals and are known for destructive foraging behaviors, which likely threatens avian communities through habitat alteration and can impact the long term structure of ecosystems where they are present.

In chapter 1, we used a combination of avian point count surveys, vegetation assessments, and camera trap surveillance to quantify how the occupancy of breeding birds in bottomland hardwood forests changed in relation to …

Causal Discovery In Time Series Data Using Deep Learning Techniques, Saima Zahin Farhana Absar

Graduate Theses and Dissertations

Causal structure learning from observational data has been an active field of research over the past decades. In the literature, different algorithms and models have been proposed, such as constrained-based methods and score-based methods including the emerging deep learning-based methods. However, most of the approaches apply to static and non-dynamic data only. In many applications, the data is temporal. For example, monitoring systems, weather surveillance systems, and stock data, to name but a few. Incorporating temporal information is an important extension of the causal discovery field. With the growth of observational data these days, the discovery of causal relationships from …

Neural Network Architecture Search Enabled Wide-Deep Learning (Nas-Wd) Integrated Hyperspectral Imaging Understanding For Woody Breast In Poultry Processing, Chaitanya Kumar Reddy Pallerla

Graduate Theses and Dissertations

The development and implementation of a Wide & Deep (WD) learning model tailored for classification and regression tasks utilizing spectral data provides a robust solution to evaluate woody breast (WB) conditions in poultry fillets. This process begins with thorough data preprocessing, which includes loading spectral and classification datasets, imputing missing values with medians, and splitting the data into training and testing sets to ensure rigorous model evaluation. The WD model architecture integrates wide linear models and deep neural networks to harness the strengths of both approaches. The wide component excels at memorizing sparse feature interactions, while the deep component captures …

Two-Photon Imaging For Characterizing Tumor Microenvironmental Changes In Non-Small Cell Lung Cancer Associated With Metastatic Recurrence, Paola Monterroso Diaz

Graduate Theses and Dissertations

Lung cancer remains the leading cause of cancer deaths, comprising nearly 25% of all cancer deaths (Sung et al., 2021a). The five-year survival rate of patients with non-small cell lung carcinoma (NSCLC) remains significantly low given that over half present with locally advanced or metastatic disease at time of diagnosis, and experience tumor recurrence following therapeutic intervention (Tamura et al., 2015; Uramoto & Tanaka, 2014). Current evaluation techniques to assess treatment response are lacking, given they are implemented several weeks after treatment completion and are solely based on anatomical changes in tumor size, forgoing other criteria such as functional or …

Blend Matters: Interactions Of Rice Cultivars On Milling, Physico-Chemical & End Use Traits, Bindu Regonda

Graduate Theses and Dissertations

Rice blending or mixing of different rice cultivars, a common practice in the industry, significantly impacts processing efficiency and end-product quality, yet its effects on end products remain understudied. This research investigated the implications of blending contemporary Arkansas rice cultivars through two comprehensive studies focusing on milling yields and physicochemical properties, instantization, and parboiling processes. Five long-grain cultivars, including hybrids (RT 7521 FP, RT 7321 FP, XP 753) and purelines (Ozark, CLL 16), were blended in various combinations and different drying.

The first study revealed that blending significantly affected milling yields and physicochemical attributes. Pre-drying blending yielded better results compared …

Carbon Dioxide Dynamics In The Carbonate Critical Zone, Savoy Experimental Watershed, Arkansas, Usa, Michael Darvin Jones

Graduate Theses and Dissertations

The dynamics of carbon dioxide (CO₂) within the Earth’s critical zone (CZ) are essential for driving spatial and temporal variations of carbonate dissolution and precipitation, which are fundamental to subsurface porosity and permeability development. However, there is still a significant knowledge gap regarding the patterns of CO₂ transport and production within the carbonate critical zone (CCZ). In this study, we investigated these dynamics within a mantled karst terrain at the Savoy Experimental Watershed (SEW) in Northwest Arkansas.

Previous monitoring of partial pressure of CO₂ (PCO₂) and dissolution rates at karst springs in …

Comparison Of Statistical And Machine Learning Genomic Prediction Methods In Plant Breeding: Case Studies In Maize And Soybean, Igor Kuivjogi Fernandes

Graduate Theses and Dissertations

Plant breeding is essential to increase genetic gain and food production worldwide. This study was conducted to evaluate new ways to use machine learning (ML) to tackle plant breeding challenges, where two ideas were tested — the first chapter focuses on how to combine genetic and environmental data using ML to improve the prediction of maize grain yield in multi-environment trials, while the second chapter centers on how to couple feature selection of molecular markers with ML to enhance prediction of yield in soybean, and, in both cases, ML approaches were compared to well-established statistical methods greatly adopted by the …