Digital Commons Network^™

Internalism, Externalism, And The Phenomenology Of Epistemic Justification, Steven Winterfeldt

Theses and Dissertations--Philosophy

This dissertation applies a phenomenological method of analysis to the dispute between analytic internalists and externalists regarding epistemic justification. Traditionally, the justification condition on knowledge has been interpreted as an internal condition, but the growing popularity of the externalist antithesis has placed internalism on the defensive. Ultimately, however, the dispute appears to have fallen into an impasse. I identify a set of four arguments or cases that, when taken together, prompt us to adopt a set of contradictory conclusions about the necessary and sufficient conditions for justified belief. Moreover, none of the analytic views of justification surveyed seem to be …

Harnessing Ethnicity For Effective Leadership: Reimagining Ethnic Politics As An Institutional Asset In Africa, Obaloluwa A. Aka

Theses and Dissertations--Political Science

Ethnic identity remains one of the most enduring forces shaping political behavior and leadership in Africa. Often viewed as a source of division, this study reframes ethnicity as an institutional asset capable of fostering accountability and enhancing leadership quality. Drawing on Afrobarometer Round 9 data from 35 African countries, the paper shows that ethnicity consistently predicts vote choice affirming its political salience. Rather than treating this as a democratic obstacle, the analysis demonstrates that when mediated through trusted traditional leaders, ethnic identity can strengthen satisfaction with democracy, trust in institutions, and perceptions of governance. Logistic regression models reveal that trust …

Towards A Sociological Theory Of Consent And Coercion In Sexual Violence Against Women, Lisa Kistler

Theses and Dissertations--Sociology

Recent data estimate that 26.8% of adult women in the U.S. have experienced rape in their lifetime. In this context, the phrase “consent to sex” is a prominent narrative countering sexual violence. Yet, there is no consensus on the meaning of consent, nor how the practice of consent is affected by coercion, resulting in a puzzle of consent. In response, the present project brings together existing research and theory to conceptualize consent and coercion in new ways. It asks, broadly, how do different forms of coercion complicate sexual consent and contribute to sexual violence against women today and answers this …

A Comprehensive Exploration Of Stress And Depressive Symptoms In Farm Populations, Julie C. Derringer

Theses and Dissertations--Nursing

High rates of depression and suicide continue to be a concern, despite four decades of growing research into the mental health of farmers. Most farmers have an awareness of a need for improved mental health, but a lack of knowledge persists. As agricultural production demands increase and the number of family farms decreases, the stress placed upon farmers to support the food chain is higher than ever. Understanding the association between farm demands and resources among farmers is key for the development and implementation of programs to decrease occupational stress and depressive symptoms to improve mental health outcomes across farming …

Using Hyperactive Shp-2 Mutants, A Phosphatase, To Identify Interactions With The Rna Helicase Ddx3, Devin Montgomery

Theses and Dissertations--Pharmacy

Protein-protein interactions are critical in cellular signaling pathways. This project investigates binding interactions between SHP-2, a tyrosine phosphatase, and DDX3, an RNA helicase. There is a specific focus on the impact that gain-of-function SHP-2 mutations may impact binding to DDX3 via conformational change. Using immunoprecipitation protocols as well as western blotting we were able to provide insights into SHP-2 molecular mechanisms and subsequent binding to DDX3.

Anxiolytic Intervention: Modulation Of Cell Types Due To Nicotine Withdrawal, Taylor Elder

Theses and Dissertations--Pharmacy

Nicotine use disorder (NUD) remains a leading cause of preventable disease, yet the neurobiological mechanisms underlying nicotine withdrawal are incompletely understood. Emerging evidence implicates neuroimmune signaling and astrocytic regulation of glutamate in shaping the withdrawal-associated affective phenotype. This dissertation investigated these processes using multiple nicotine administration paradigms including osmotic minipump implant, cigarette smoke exposure, and nicotine vapor inhalation to model diverse routes of human nicotine intake.

Chapter 2 examines the effects of these three modes of administration on neuroinflammation and validation of nicotine delivery. Nicotine exposure was confirmed through receptor [³H]Epibatidine nAChR binding assay and serum cotinine measurements. …

Investigating The Role Of Dynamic Signaling Of Nrg3-Erbb4 In The Prefrontal Cortex In Mediating Nicotine Withdrawal Phenotypes, Emily Prantzalos

Theses and Dissertations--Pharmacy

While several pharmacotherapies are currently available for nicotine use disorder (NUD), smoking cessation success rates remain below 10% each year. The molecular mechanisms underlying failed quit attempts continue to represent a critical gap in our knowledge. However, recent advances in understanding the genetic contributions to nicotine dependence offer a promising avenue for developing more effective cessation therapies. Prior research has identified genetic variation in Neuregulin 3 (Nrg3) and its cognate receptor ErbB4 as potential contributors to affective nicotine withdrawal (WD) phenotypes and cessation outcomes. Therefore, this dissertation aims to systematically investigate the region-specific, functional role of the Neuregulin Signaling Pathway …

Leveraging Transcriptomics And Behavior To Investigate Potential Neuronal And Glial Drivers Of Substance Use Disorder Endophenotypes, Jack V. Keady

Theses and Dissertations--Pharmacy

Over 54 million Americans needed substance use treatment in 2023. While there are many facets of substance use disorder, two major issues of interest are the negative reinforcing aspects of substances of abuse, manifesting in part as withdrawal symptomologies, and why a subset of people who use substances of abuse escalate to a use disorder. Nicotine exposure models were used to investigate the mechanisms of withdrawal endophenotypes, as smoking is the leading cause of preventable death in the United States, and a fentanyl self-administration model was used to probe individual differences in escalation phenotypes, as 80% of overdose deaths in …

The Impact Of Maternal Environmental Exposures On The Immune Landscape Of The Maternal-Fetal Interface, Heather E. True

Theses and Dissertations--Pharmacy

Maternal environmental exposures and inflammation are known to impact fetal development in utero as well as increase the risk for chronic diseases later in life. Therefore, it is essential that we understand how the maternal environment alters placental structure and immune function.

Therefore, we isolated fetal (chorionic villous) tissues from the placentas of healthy pregnant participants (control) and those with inflammatory conditions, including SARS-COV-2 infection, pregravid obesity, and opioid use disorder. Isolated placental leukocytes were subjected to a series of assays to uncover the phenotypic, functional, and transcriptional (single-cell RNA-sequencing) landscape of placental immune cells. Additional placental tissues were subjected …

Collision Avoidance Information System Utilizing Machine Learning Image Recognition, Michael W. Long

Theses and Dissertations--Mining Engineering

This thesis addresses significant safety challenges presented by powered haulage fatalities in underground mining by developing and evaluating a machine learning-driven Collision Avoidance Information System (CAIS). The research utilized a ZED 2i camera to capture both RGB and depth data for enhanced spatial awareness in visually limited underground environments. A specialized dataset of underground mining equipment was captured from limestone and zinc mines, annotated, and used to train a segmentation network. The CAIS was field-tested in diverse underground settings, achieving an accuracy of 82% in a limestone mine similar to the training data, but a lower accuracy of 45% in …

The Dynamic Material Response Of Csa Cement Using A Split Hopkinson Bar, Elliott L. Morgan

Theses and Dissertations--Mining Engineering

The University of Kentucky Center for Applied Energy Research (CAER) Cementitious Materials Group is developing a pourable Calcium Sulphoaluminate (CSA) cement-based concrete for rapid repair applications. Due to dynamic events like vehicle strikes, ballistic events, or other dynamic loading events, the dynamic material characteristics are important for understanding how the material will respond. A large diameter Split Hopkinson Pressure Bar (SHPB) was used to test samples of the pourable CSA cement and determine its dynamic material properties in the early strength development phase. 24 samples were tested in 7 day intervals for 28 days. Samples were prepared targeting a length …

Temporal Machine Learning For Predicting Accidents And Violations In The Mining Industry, Nathan T. Kelley

Theses and Dissertations--Mining Engineering

This thesis examines the predictive capability of a temporal machine learning model for forecasting future accidents and violations at individual mines, based on historical data. Mine accidents were categorized by accident classification and violations were categorized by the Part Section. The primary datasets utilized were the mine safety and health administration’s (MSHA’s) Accident Injuries and Violations datasets. The available datasets were cleaned and organized by mine type and commodity, then divided into separate subsets for training, validating, and testing. Different models, cutoff metrics, learning rates, number of hidden layers, data processing methods, data processing divisions, number of points observed …

An Autonomous Robotic Inspection System For Underground Mines Using Unmanned Aerial Vehicles (Uavs), Kiazoa M. Joao

Theses and Dissertations--Mining Engineering

Underground mining environments pose unique safety challenges for workers due to poor visibility, unstable ground conditions, and the absence of GPS signals. To adhere to safety and health standards, underground mines are required to perform safety inspections regularly. Conventional safety inspections require personnel to enter the hazardous environment, highlighting the need for a safer, remote alternative. The use of UAVs for safety inspection in underground mines is a somewhat novel idea but has shown great promise. While Unmanned Aerial Vehicles (UAVs) cannot eliminate all hazards associated with mining, they provide critical support by accessing hazardous or restricted zones that are …

Analysis Of Dynamic And Final Surface Subsidence Movements Over Subcritical Panels In The Eastern Us, Mauricio Parra Valencia Sr

Theses and Dissertations--Mining Engineering

Subsidence prediction is a critical field in mining engineering, focusing on anticipating ground movements caused by underground coal extraction. Accurately forecasting these movements is essential for protecting surface structures and infrastructure from damage. However, despite extensive research by mining professionals worldwide, reliable prediction remains challenging, especially in complex environments like subcritical mining areas and locations characterized by highly variable topography. These conditions introduce non-linear rock mechanics that often complicate the application of traditional predictive models. This thesis utilizes measured subsidence data related to the extraction of two adjacent longwall panels in a deep coal mine in the eastern US to …

Analysis Of Ptfe Radial Lip Seals For Wheel Bearing Applications, Madison Vogt

Theses and Dissertations--Mechanical and Aerospace Engineering

A numerical analysis was conducted to investigate the viscoelastic effects of nonlinear materials on the sealing zone and contact pressure distribution of radial lip seals in a conventional geometric topology. The use of nonlinear materials in radial lip seal applications is desirable to improve operation and reliability of rotating machinery due to their high operating temperatures, chemical compatibility, and low friction coefficients. Examples include, but are not limited to, seals within industrial air compressors, turbine engines, aircraft landing systems, chemical processing equipment, and Freon pumps. This work focuses on analyzing the nonlinear viscoelastic response of pure Polytetrafluoroethylene (PTFE) and PTFE …

Simplified Molecular Diagnostics Methods For Environmental Testing Of Pathogens And Other Applications, Mohammad Dehghan Banadaki

Theses and Dissertations--Mechanical and Aerospace Engineering

Environmental Surveillance (ES) has emerged as a powerful tool to monitor the emergence and persistence of a pathogen within a facility or community using wastewater/water analysis. Over the past four years, implementation of ES has experienced an explosive acceleration, driven by efforts to monitor the spread of SARS-CoV-2, which has made ES a routinely used public health tool in many locations. We can now use ES to measure the emergence/presence/abundance of different viruses (e.g., SARS-CoV-2, influenza, mpox), bacteria (e.g., E. coli, V. cholerae, antibiotic-resistant strains), fungi (e.g., C. auris), and other biological markers indicative of infectious diseases. However, its broad …

Determination And Limitations Of Blocked Forces In Industrial Settings, Matthew Smither

Theses and Dissertations--Mechanical and Aerospace Engineering

Transfer path analysis methods have been used for decades to determine noise and vibration paths emanating from machinery. In its advent, the machinery source had to be disconnected from the receiver it was attached to in order to gain useful information about each. Further advances in methodology allowed for determining machinery input forces without decoupling them from the structures they were attached to. However, these methods were limited in that the machinery and structures were required to be treated as a system. Thus, any force data obtain was only useful in the configuration it was measured in. Finally, a method …

In-Situ Characterization Of Damage Mechanisms In Ceramic Matrix Composites, Cle' E. Sanchez

Theses and Dissertations--Mechanical and Aerospace Engineering

Ceramic Matrix Composites have many advantages, attracting the nuclear, aerospace, and automotive industries with their high heat stability, strength, and oxidation resistance. However, challenges are presented when machining these materials due to the brittle properties and complicated microstructure. The objective of this project was to identify damage mechanisms that occur when a CMC is orthogonally machined and the cutting mechanics are observed in-situ, followed by post-cut characterization of the as-machined surface morphology. In this analysis, the main variable is the feed rate, which can influence the damage mechanisms, such as matrix failure (matrix cracking) or fiber failure (pullout). Through this …

In Situ Bourbon Barrel Measurements Of Alcohol By Volume And Liquid Depth Using Borosilicate Glass Probes And Near Infrared Absorption Spectroscopy, Trent T. Reed

Theses and Dissertations--Mechanical and Aerospace Engineering

In pursuit of measuring different variables present in bourbon barrels, absorption spectroscopy was utilized to ensure that different ethanol and water concentrations can be differentiated using a broadband light source and near infrared spectrometer in a simple cuvette-based testing setup. The intensity and absorption plots gathered of different ethanol and water mixtures were then analyzed using proper orthogonal decomposition (POD) to break down the data into modes which represent specific variables of interest, specifically ethanol concentration or alcohol by volume (ABV). The modes were then utilized to find mode constants to represent the data taken from cuvette samples which were …

Numerical Investigation Of Wind Disturbance Around A Multirotor Uav In Crosswind And Vertical Flight, Garrison Page

Theses and Dissertations--Mechanical and Aerospace Engineering

Uncrewed Aerial Vehicles (UAVs) are being increasingly utilized in a wide range of research applications, especially in meteorology. This is due to such factors as their ease of use, maneuverability compared to other forms of data collection, and for rotor- craft, the ability to hover. However, the rotorwash generated by UAVs can introduce significant disturbances, potentially affecting measurement accuracy from sensors. While several studies have investigated the rotorwash of individual UAVs utilizing Particle Image Velocimetry (PIV) and Computational Fluid Dynamics (CFD), there is limited exploration into how different rotor configurations and external wind conditions influence regions of turbulent flow around …

Growth Kinetics And Stability Of Metal Halide Perovskite Nanocrystals: Influence Of Stirring Speed And Water Exposure, You-Lin Huang

Theses and Dissertations--Mechanical and Aerospace Engineering

Cesium lead bromide (CsPbBr₃) perovskite nanocrystals (NCs) have garnered significant interest due to their exceptional optoelectronic properties, including high photoluminescence quantum yield, tunable bandgap, and excellent carrier dynamics. These attributes make them promising candidates for applications in light-emitting diodes, photovoltaics, and sensing technologies. However, optimizing their synthesis and improving their environmental stability remain critical challenges. This dissertation explores the growth kinetics of CsPbBr₃ NCs, focusing on the effects of stirring speed and water exposure on their structural and optical properties.

The synthesis of CsPbBr₃ NCs was performed using both mechanochemical (MC) and antisolvent methods, enabling an …

Acoustic Characterization Of A Quadcopter Using A Test Stand, Jared Schmal

Theses and Dissertations--Mechanical and Aerospace Engineering

Unmanned Aerial Vehicles (UAVs) with multirotor propulsion and control, commonly called drones or multicopters, generate a complex acoustic field that is not entirely understood. Many components and their interactions contribute to the overall noise level and behavior of the acoustic field. However, performing acoustic measurements on a multicopter in a confined space, such as a small anechoic chamber, can be an extremely difficult and time-consuming process. A test stand was developed to allow for rapid and safe acoustic measurements in a controlled environment. The design, development, and initial measurements are discussed. The performance and acoustic response are assessed to examine …

Analysis Of Closed-Loop Dynamical Systems Using Relu Nns, Pouya Samanipour

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis develops a framework for analyzing the stability and invariance properties of closed-loop dynamical systems whose dynamics are derived from neural networks with rectified linear units (ReLUs). The ReLU neural network defines continuous piecewise affine (PWA) functions, which makes them ideal for analysis using polyhedral geometry and optimization techniques. To begin, we introduce two exact algorithms for enumerating polytopic regions of affine behavior induced by ReLU networks: a half-space-based method that checks the feasibility of activation patterns and a geometric vertex-based method. Using these methods, we are able to perform precise region-wise analysis, and these methods serve as the …

In-Situ Informed Modeling And Characterization Of Friction And Built-Up Edge In Machining Of Aerospace Alloys, Avery Hartley

Theses and Dissertations--Mechanical and Aerospace Engineering

Machining is by no means a new manufacturing process. However, it is separated from other traditional deformation processes by its extreme temperatures and strain rates. The function and life of a multitude of products and mechanical components are dependent on the material properties induced by changing the surface through machining. Furthermore, the tools used within machining are often expensive and material reserves are sparse. The understanding the mechanics of the machining process, especially related to the friction of the tool and workpiece, helps to further the life of tools and parts to minimize economic and environmental impact.

Current friction modeling …

Engineering A Novel Solvent Regenerator That Leverages Electrochemically Induced Ph Swings For Direct Air Capture And Hydrogen Generation, Emmanuel Aluhunmile Ohiomoba

Theses and Dissertations--Mechanical and Aerospace Engineering

Direct Air Capture (DAC) is considered to be a key component for achieving global net-negative emissions. However, to capture CO₂ at the low concentrations in the atmosphere requires materials with high affinity for CO₂. This makes the solvent-based chemical approach for DAC more applicable compared to physical approaches. Nonetheless, regenerating the capture solvent presents a significant challenge due to high heat requirements for thermal decomposition of carbonates. Leveraging electrochemical principles provides an opportunity to simplify the regeneration process, thus, this work focuses on engineering an electrochemical solvent regenerator for recovering alkaline solvents for DAC, with co-production of …

Machining-Induced Residual Stress Modeling Using Physics-Informed Neural Networks, Md Mehedi Hasan

Theses and Dissertations--Mechanical and Aerospace Engineering

Process-induced residual stress (RS) plays a critical role in determining the structural integrity, fatigue life, corrosion resistance, and dimensional stability of manufactured components. Tensile residual stress can be harmful to the machined workpiece by lowering fatigue strength, while compressive residual stress helps to prevent such issues. Therefore, accurate prediction and control of machining-induced residual stresses are essential for optimizing manufacturing processes and enhancing component performance. However, existing modeling approaches—empirical, analytical, and numerical—often have limited predictive accuracy, demand extensive calibration, or involve high computational costs. Traditional finite element analysis (FEA) provides modeling insights but is constrained by its high computational cost …

Scaling Investigations Of Wall-Bounded Turbulent Flow, Nikolay Gustenyov

Theses and Dissertations--Mechanical and Aerospace Engineering

This dissertation investigates the scaling behavior, structural organization, and modeling of turbulence in wall-bounded flows across a wide range of Reynolds numbers and surface conditions. Through high-resolution experimental studies in zero-pressure- gradient turbulent boundary layers and pipe flows (2000 < Reτ < 38 200), the wall- dependence of turbulent length scales is examined with a focus on both small-scale dissipative motions and large-scale structures. When external intermittency is properly accounted for, dissipative motions are shown to obey inner scaling even in outer- scaled regions, while large-scale motions exhibit outer scaling behavior deep into the inner region. These findings are consistent across internal (pipe) and external (boundary layer) flows and are reflected in distinct features of the longitudinal wavenumber spectrum.

The dissertation also explores the development of a turbulent boundary layer transitioning from a smooth solid wall to a liquid surface. An internal boundary layer forms in response to stochastic surface waves, resulting in increased turbulence intensity and displaced momentum relative to solid-wall cases. Near the liquid surface, turbulence generation aligns with wavenumbers corresponding to the surface waves, introducing distinct small-scale …

Development Of An Immersed Boundary Method-Wall Modeled Large Eddy Simulation Approach For Incompressible Flows And Aeroacoustic Predictions, John C. Higgins

Theses and Dissertations--Mechanical and Aerospace Engineering

The performance capabilities of rotorcraft have improved significantly in the past decade as both manned and unmanned rotorcraft become a larger part of future transportation systems. Private companies as well as various government offices have worked to develop capabilities ranging from transportation/package delivery to intelligence/surveillance to livestock monitoring. Their practicality in both rural and urban areas, however, is questionable due to the significant tonal and broadband noise which is produced by the rotors. Public acceptance of rotorcraft, namely small Unmanned Aerial Vehicles (sUAVs), in transportation systems is an issue largely associated with the noise generation and it's effect on nearby …

Fluid Pathways For Enhanced Mass Transfer In The Micro Regime: Applications In Novel Pumpless Redox Flow Cell And Zinc Finger Protein-Based Dna Detection, Shaikh Al Mahmud Bhuiyan

Theses and Dissertations--Mechanical and Aerospace Engineering

Precise fluid transport through microscale geometries can help optimize electrochemical and biochemical processes by maximizing the mass transfer rate of reactants. By introducing intricate structural features inside microchannels, it is possible to manipulate the fluid motion and direct the flow towards any surface of interest. In this study, we have demonstrated that rationally designed fluid pathways can improve the performance of electrochemical and biochemical systems.

The emergence of additive manufacturing has enabled rapid fabrication of robust structures with intricate features to guide fluid motion. However, their application in nonaqueous electrochemical systems has been limited due to their interaction with organic …

Direct Numerical Simulation Of Pulsating Flow In Curved Pipes: Insights Into Aortic Dissection In Humans, Gokul Anugrah Gopakumar

Theses and Dissertations--Mechanical and Aerospace Engineering

This dissertation investigates the hemodynamics of pulsating blood flow in curved vessels through direct numerical simulations (DNS), with the overarching aim of uncovering fluid dynamic mechanisms linked to the onset and progression of aortic dissection in humans. The work is structured in two parts: (i) fundamental studies in idealized geometries and (ii) preliminary investigations in patient-specific anatomies. In the first part, curved pipe models representing the aortic arch are used to isolate the effects of pulsation frequency, amplitude ratio, and curvature ratio on transitional and turbulent flow dynamics. The simulations reveal that curvature-driven centrifugal forces shift the peak velocity toward …