UARK (University of Arkansas )
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Contrastive Loss in Recommendation Systems
No full textA recommendation system is a bridge between users and products, which is widely used in e-commerce such as Amazon and Netflix. This study investigates the use of Graph Neural Networks (GNNs), Light Graph Convolution Network(LightGCN) and Graph Sample and Aggregate (GraphSAGE), in the recommendation system on two categories of Amazon review datasets ( All Beauty and Tools and Home Improvement ). The novelty of this work includes combining supervised and self-supervised learning through Weighted Approximate Rank Pairwise (WARP) and Information Noise-Contrastive Estimation (InfoNCE) losses, to optimize the embeddings of users and recommended items in the shape of a ranking list. The results show that GraphSAGE outperforms LightGCN, and more specifically, among GraphSAGE models, the one with the combination of WARP and InfoNCE losses performs very well. The reasons behind these improvements could be that GraphSAGE leverages the node features to capture both collaborative and content-based signals. Moreover, it samples a fixed number of neighbors, not all of them, which reduces the noise’s impact, specifically in sparse and large datasets. GraphSAGE uses the ReLU activation function, which makes it capable of learning non-linear behaviors, such as price sensitivity. Besides the model, contrastive learning (InfoNCE) offers robustness and consistency by creating two augmented views of a graph. Optimization in InfoNCE aims to make these two graphs’ embeddings similar. Overall, this work contributes to recommendation systems through feature engineering, novel loss design, and scalability solutions for large-scale data. It can be shown that contrastive loss will improve this system’s performance significantly
The Fate of Intra- and Extracellular Antibiotic Resistance Genes Through Advanced Wastewater Treatment Process
No full textMore areas across the globe are becoming affected by water stress or water scarcity. The decrease in available freshwater due to overconsumption reveals the direct need to consider other sources for necessities such as drinking water or food production. Agricultural irrigation uses 70% of the world’s freshwater, making the focus on safe and reliable reclaimed water for agricultural reuse imperative. However, contaminants of emerging concern (CECs), such as antibiotics and their resulting antibiotic resistance genes (ARGs), can spread and affect human health if reclaimed water is not treated to the proper level. Antibiotics are widely used in human medicine and animal husbandry, developing into the problem of antibiotic resistance. ARGs can multiply throughout the environment via vertical or horizontal gene transfer (HGT) and can be present as intra- or extracellular DNA (iDNA and eDNA, respectively). eDNA can bind to sediment and particulate matter, shielding it from possible degradation and inactivation by wastewater treatment plant (WWTP) processes. WWTPs are typically unable to target and remove eARGs; however, advanced treatment processes for reclaimed water may be able to remove them. This study measured ARGs in various environmental samples, including lakes, ponds and wastewater treatment facilities with a pilot advanced treatment train. Five ARGs corresponding with resistance to different antibiotic classes (tetracyclines, sulfonamides, and macrolides) were quantified using qPCR. Different levels of ARGs were detected in all samples collected. A separation protocol was also tested for iDNA and eDNA in water samples by investigating the recovery efficiency of each. However, results from this study showed that the proposed separation protocol has a low recovery efficiency for eDNA, and that more research on iDNA and eDNA separation is needed in the future. Moreover, the advanced treatment processes in the pilot facility exhibited inconsistent ARG removal rates at all ozone dosages tested, which is most likely attributed to the differences in individual ARG structures, as well as the sequence of advanced treatment processes
Limb Regeneration in Damselflies Based on Developmental Stage
No full textInjury is common in wild animals, yet some species possess an adaptive advantage: regeneration. Enallagma vesperum, a species of damselfly, exhibits this regenerative ability, though its persistence and effectiveness across developmental stages remain poorly understood. While previous studies indicate that regeneration ceases following adult emergence, it is unclear whether this ability also diminishes prior to the final larval molt. This study investigated the effectiveness of limb regeneration in E. vesperum across early and late larval instars. I hypothesized that earlier instars would exhibit greater regenerative success due to fewer competing energetic demands compared to later instars, which may prioritize resources for processes such as tissue differentiation and physiological preparation for metamorphosis. My results support this prediction, demonstrating that E. vesperum in early developmental stages exhibited much greater limb regenerative success than those in later stages. These findings highlight the role of developmental timing in shaping regenerative capacity and suggest potential trade-offs between regeneration and other growth-related processes as larvae approach metamorphosis
Leadership, Culture, and Operational Excellence: An Experiential Study of Aldi’s District Manager Internship
No full textThis thesis highlights the organizational strategy, culture, and operating structure of the grocery retailer Aldi, as well as examines the experiential learning gained through the company’s District Manager Internship Program. Aldi’s immense success as a global leader in the grocery retail industry is rooted in the company’s commitment to its three core values of simplicity, consistency, and responsibility. These values drive both business practices and employee culture. Through firsthand experience in the internship within the Olathe Division, I gained exposure to Aldi’s retail operations, leadership expectations, and management processes. My experiences included learning the company’s standard operating procedures, conducting store walks with store managers, audits, supported the hiring process, and managing store challenges. The main component of this internship involved creating and conducting a research project on employee training compliance. This project included developing a survey for over 100 store managers in the division and analyzing real-time data from multiple stores. Findings from this process revealed gaps in employee training methods, training fatigue, and inconsistencies in protocol adherence. By presenting these issues, along with the data and actionable recommendations to divisional leadership, this project contributed insights that emphasized the need for improved communication, a more streamlined training process, and better alignment between corporate expectations of employees and in-store realities. Overall, this experiential study demonstrated how structured internship with Aldi cultivated leadership skills, informed operational improvements, and supported Aldi’s continued success as a leading and efficient grocery retailer
Onward, Christian Soldiers: The Material Rhetoric of Becoming Fascist in Parachurch Scouting Organizations
No full textThis thesis provides a material rhetorical analysis of Trail Life USA and American Heritage Girls, two Christian nationalist scouting organizations that aim to renew and restore their cultural dominance across America. In examining how these programs route children’s bodies through ritual and affective indoctrination, I find that a fascist becoming underpins these groups’ (re)production of perfect, patriotic children. The first chapter discusses how boys enrolled in Trail Life USA become fascist as self-defense against American boyhood’s perceived eradication. Trail Life USA restores masculinity through rituals of autogenetic sovereignty, returns to originality through homosocial and affective intensity, and invocations of exceptional heritage in defense of their civic, political, and martial authority. In the second chapter, I examine how American Heritage Girls transcend the affective gender binary while remaining tethered to the antifeminist fascism. To preserve their second-rate citizenship under white male supremacy, girls elevate themselves through performances of countercultural authenticity and punishing threats by exercising masculine affect and authority. This thesis argues that scouts’ embodied experiences in these programs function as virtual repetitions of combined pastness and futurity, through which children become the affects and agents of fascism
A Multicomponent Microneedle Patch for the Delivery of Meloxicam for Veterinary Applications
No full textVeterinary medicine requires innovative drug delivery strategies to enhance therapeutic efficacy while minimizing stress and handling. This dissertation explores the development and application of biodegradable microneedle patches for the transdermal delivery of meloxicam in livestock, offering a minimally invasive alternative to traditional administration methods. The research investigates the fabrication and characterization of microneedles using polyvinyl alcohol, collagen, and chitosan blends, demonstrating their mechanical strength, biocompatibility, and ability to facilitate sustained drug release. In vitro and in vivo evaluations confirm effective skin penetration, dissolution, and localized drug delivery. Pharmacokinetic studies highlight anatomical site-dependent variations in drug absorption, emphasizing the need for strategic placement to optimize systemic bioavailability. Additionally, the limited solubility of MEL is identified as a key factor influencing drug uptake, prompting consideration of solubility-enhancing approaches. Beyond technical validation, this work explores the translational potential of microneedle technology in veterinary pain management, addressing challenges such as regulatory compliance, market adoption, and economic feasibility. Findings underscore the potential of microneedle patches to improve livestock welfare and streamline drug administration practices. Future research should focus on optimizing formulation strategies, expanding therapeutic applications, and advancing commercialization efforts to integrate this technology into routine veterinary care
Hierarchical Model for Multivariate Spatial Data with Application to Occurrence of Chronic Diseases: Hypertension and Diabetes
No full textChronic non-communicable diseases (NCDs), particularly hypertension and diabetes, are growing public health concerns in low- and middle-income countries like Bangladesh. These diseases often co-occur and exhibit notable spatial heterogeneity influenced by socio-demographic and environmental factors. This thesis presents a Bayesian multivariate spatial probit modelling framework to jointly analyze the prevalence of hypertension and diabetes using data from the 2022 Bangladesh Demographic and Health Survey (BDHS). The study incorporates individual-level covariates—such as age, sex, BMI, education, and wealth index—and a spatially structured random effects model, which is modelled via intrinsic Conditional Autoregressive (ICAR) priors at the district level. Gibbs sampling is employed to estimate model parameters and latent spatial effects. Results reveal significant spatial clustering in disease risk and strong associations between chronic conditions and socio-demographic factors. The joint modelling approach enhances estimation efficiency and facilitates the identification of high-risk districts where public health interventions are likely to have the most significant impact. Model performance is evaluated using the Deviance Information Criterion (DIC), effective parameter count, and Moran’s I statistic to confirm spatial dependencies. This research provides an integrated statistical tool for understanding the co-distribution of chronic diseases and supports evidence-based policy planning in Bangladesh
Between Compliance and Commitment: Community College Administrators and the Politics of DEI Policy Implementation
No full textThis qualitative case study explores how community college administrators navigate the complex and politically charged landscape of diversity, equity, and inclusion (DEI) policy implementation in the face of evolving state legislation. Grounded in Michael Lipsky’s theory of Street-Level Bureaucracy, the research examines how mid- to senior-level administrators perceive their interpretations, mediations, and actions on DEI mandates in contexts where such policies are contested or pressured. Using semi-structured interviews with administrators across multiple community colleges, the study investigates the tension between institutional commitment to DEI values and the necessity to comply with external political and legal directives. The study contributes to the literature on higher education governance, state policymaking and administrative discretion, offering implications for how colleges can maintain inclusive practices under the strain of increasing political polarization and policy rollback
Factors Associated with Farm Service Agency Direct Farm Ownership Loan Delinquency
No full textThis thesis investigates the factors associated with loan defaults in the USDA\u27s Direct Farm Ownership (FO) loan program, emphasizing factors that affect how long it takes to default. This study uses a Cox Proportional Hazards model on a dataset of more than 47,000 loan records originated during 2011-2020 to identify loan characteristics, financial factors, and geographic settings related to the likelihood and timing of delinquency, which is defined as being 90 days past due. Recent research has focused on differences in loan outcomes based on demographics. This study, on the other hand, focuses on loan size, interest rates and terms, and borrower solvency, liquidity, and previous credit history, including loan restructuring, as risk factors. Kaplan-Meier survival curves and multivariate hazard ratios show that factors like high debt-to-asset ratios, high interest rates, and previous restructurings increase delinquency risk significantly. There is also a lot of variation in the chances of loans surviving in different regions. For example, loans in the Southern Seaboard and Eastern Uplands have higher hazard rates. The results also show that borrowers who get targeted loans based on their experience, gender, or race and ethnicity are more likely to be late on their payments. These results have direct effects on how to assess risk and make policies in agricultural finance. They show that we need to create more nuanced ways to help borrowers and tailor loan servicing strategies
Host-virus Interaction Dynamics Using Sulfolobus Spindle-shaped Virus and Host Sulfolobales System
No full textThe Sulfolobus Spindle-shaped virus (SSV) is among the most studied archaeal viruses, particularly in extreme environments. This virus predominantly infects multiple Crenarchaea from the Sulfolobaceae family. These hosts thrive in extreme environmental conditions, such as sulfuric hot springs, with a pH of 2 to 4 and a temperature of 76-80˚C. Sulfolobales exhibit a wide geographical distribution across volcanic hot springs. The Sulfolobus Spindle-shaped Virus (SSV), encompassing strains such as SSV1 and SSV8, employs a non-lytic replication strategy in hosts belonging to the order Sulfolobales. The SSV-Sulfolobales system can be cultured in liquid and gellan gum solid media. A comprehensive study has been performed to determine the host range of a specific SSV type and identify the hosts susceptible to SSV infection. This study examines the multiple methods used in SSV titering and the impact of each virus particle count technique on the interactions between single viruses and single hosts (SVSH) across multiple sympatric and allopatric host-virus pairs. This involves conducting proteomic analysis, such as the regulation of heat shock proteins (HSP) of the host after each round of SVSH infection. This study focuses on two viruses: a low-virulence strain (SSV1) and a highly virulent strain (SSV8), which infect hosts of the Sulfolobales from various biogeographic regions. SSV infection in Sulfolobales hosts resulted in growth inhibition; hence, SSV infection may potentially serve as an environmental stressor on hosts and regulate Archaeal group II chaperonins (also known as Heat Shock Proteins). This study focuses on the transcriptomic and proteomic regulation of Heat Shock Proteins in the S. solfataricus P2 strain infected with SSVs (e.g., SSV1 and SSV8). It compares the outcomes with those of uninfected controls to explore whether viral infection induces sufficient stress to upregulate Heat Shock Proteins (HSPs). This dissertation elucidates how variations in elemental mass influence elemental stoichiometry, which, in turn, can either promote host growth or facilitate virus propagation by using the SVSH on S. islandicus (both natural and cured strain) infected with SSV1 and SSV8. This pivotal research will explore previously uncharted territories and a positive correlation between relative virulence and elemental stoichiometry in stably SSV-infected Sulfolobales. One of the future aspects of this study will be to complement the genomic and transcriptomic analysis of both the host and the virus, which may contribute to providing a definitive understanding of their differential interactions. Key Words: Sulfolobales, Sulfolobus Spindle-shaped Virus (SSV), Crenarchaea, SVSH, heat shock proteins, infection dynamics, relative virulence