Physical Sciences and Mathematics Commons^™

Mercury Biomagnification In Aquatic Food Webs Of Great Smoky Mountains National Park, Zachary Winston Clark

Masters Theses

Mercury is a widespread pollutant threatening human, fish, and ecosystem health on a global scale. Biomagnification concentrates mercury in upper trophic level organisms including predatory fishes, a primary route of dietary mercury exposure for humans. However, mercury biomagnification is not well understood in stream ecosystems, especially in places with no known point sources of contamination. A 2016 study revealed that Smallmouth Bass Micropterus dolomeiu mercury concentrations varied between three streams in Great Smoky Mountains National Park (GSMNP), Tennessee USA. However, the reason for this spatial variation in mercury concentrations is not understood. Our objectives were to (1) measure environmental and …

Volcanic Glass As A Proxy For Paleotopography Suggests New Features In Late-Miocene Oregon, Julian Cohen, John Bershaw, Richard Hugo

Geology Faculty Publications and Presentations

Volcanic glass has been used extensively as a paleoaltimeter. Deuterium (²H) concentrations in glass have been found to be stable over geologic timescales, making δ²H (also known as δD) a reliable proxy for ancient water chemistry. However, continued work revolves around better understanding how different factors affect preserved water in volcanic ash. Here, we analyze δD in the Rattlesnake Tuff (RST), a widespread ca. 7 Ma ash-flow tuff, and create a paleoisoscape to assess variations in δD across Oregon during that time. To this end, 16 ash samples were collected across central and eastern Oregon from …

Photoelectic Driven Decomposition Of Uracil Via Hard X-Ray Irradiation, Trimaan Malik

UNLV Theses, Dissertations, Professional Papers, and Capstones

Radiation damage into biological samples creates substantial challenges across a wide range of fields, from biochemistry to materials science. This comprehensive study investigates the effects of x-ray irradiation on uracil, the only nucleobase exclusive to Ribonucleic acid (RNA), to understand how doping with 10% (by mass) of specific powdered elements impacts the sustained radiation damage. The experiments were conducted at the Brockhouse Undulator Beamline of the Canadian Light Source synchrotron. Virgin and doped uracil samples were irradiated with hard x-rays, above their respective absorption edges, and studied with x-ray diffraction to compare their decomposition behaviors. The Uracil reflections on the …

Affinity-Enhanced Microdialysis Using Covalent Organic Frameworks (Cofs) Applied To Various Non-Steroidal Anti-Inflammatory Drugs (Nsaids) And Their Metabolites, Kehinde Adedeji Olubanjo

Graduate Theses and Dissertations

Microdialysis is a valuable tool in neurosciences and pharmaceutical sciences, aiding research in drug-related areas. However, it faces a notable limitation in sampling hydrophobic analytes due to their adherence to the probe materials brought about by non-specific adsorption, thereby reducing relative recovery or overall extraction. In this work, two affinity agents, polydimethylsiloxane (PDMS) beads suspended in sodium dodecyl sulfate (SDS) surfactant and covalent organic frameworks I(COFs) were employed as affinity agents in microdialysis for the extraction of hydrophobic drugs. When PDMS beads were employed as affinity agents, at the flow rate of 1 µL/min the relative recovery of both the …

Determining The Climatic Effects Of The Central Atlantic Magmatic Province Across The End Triassic Mass Extinction In The Elliot Formation, Southern Africa, Danielle Elizabeth Oberg

Graduate Theses and Dissertations

Understanding the intricate relation between carbon-cycle perturbations, climate change, and biodiversity stability is crucial in the face of ongoing anthropogenic greenhouse-gas emissions. This thesis explores the impacts of rapid climate change induced by carbon-cycle perturbations and their potential repercussions on global climate. Large igneous provinces, particularly the Central Atlantic Magmatic Province, offer a lens through which to examine the nexus of volcanic activity, mass extinctions, and climate change. The emplacement of Central Atlantic Magmatic Province, covering vast regions across continents, emitted substantial amounts of carbon dioxide, profoundly impacting global climate and ecosystems. The end-Triassic Mass Extinction, attributed to Central Atlantic …

Investigate The Importance Of Local Magnetic Moment And Magnetic Interaction In Superconducting Fese Monolayer Using Density Functional Calculations, Sudip Pokharel

Graduate Theses and Dissertations

In this dissertation, we present two projects to study superconducting FeSe monolayer using first-principles density functional calculations. Monolayer FeSe/SrTiO3 system has very different properties as compared to its bulk counterpart in terms of critical superconducting temperature, Fermi surface topology and antiferromagnetic (AFM) stability. For FeSe monolayer, local magnetic moment (LMM) and AFM fluctuation are closely linked to superconductivity. However, LMM is not studied enough for FeSe monolayer. For FeSe/SrTiO3 system, the substrate SrTiO3 constrains the in-plane lattice constant for FeSe and also plays a crucial role in the onset and enhancement of superconductivity by providing charge transfer. The height of …

The Gravitational Wave Peep: Improved Modeling Of Highly Eccentric Emris For Lisa Signal Confusion Noise, Daniel J. Oliver

Graduate Theses and Dissertations

Scattering events around a massive black hole will occasionally toss a stellar-mass compact object into an orbit around the massive black hole, beginning an extreme mass ratio inspiral. The early stages of such a highly eccentric orbit will not produce detectable gravitational waves as the source will only be in a suitable frequency band briefly when it is close to periapsis during each long-period orbit. This burst of emission, firmly in the millihertz band, is the gravitational wave peep. While a single peep is not likely to be detectable, if we consider an ensemble of such subthreshold sources, spread across …

Analysis And Construction Of Artificial Neural Networks For The Heat Equations, And Their Associated Parameters, Depths, And Accuracies., Shakil Ahmed Rafi

Graduate Theses and Dissertations

This dissertation seeks to explore a certain calculus for artificial neural networks. Specifi- cally we will be looking at versions of the heat equation, and exploring strategies on how to approximate them. Our strategy towards the beginning will be to take a technique called Multi-Level Picard (MLP), and present a simplified version of it showing that it converges to a solution of the equation �� ∂ ud�� (t, x) = (∇2xud) (t, x). ∂t We will then take a small detour exploring the viscosity super-solution properties of so- lutions to such equations. It is here that we will first encounter …

Investigations Into The Expansion Of Breslow-Type Intermediate Reactivity Via Radical C-N Bond Homolysis, Jacklyn Simpson

Graduate Theses and Dissertations

The Breslow intermediate is a key intermediate in catalytic transformations like the benzoin condensation and Stetter reaction. These intermediates were first postulated by Ronald Breslow in 1958. Since then, a number of researchers have sought to prove their existence and expand upon the reactions possible using these intermediates. In the sixty plus years since this intermediate was first postulated the reaction scope has expanded significantly, Breslow and breslow-type intermediates have expanded to encompass benzothiazoles, imidazoles, benzoimidazoles, triazoles, thiadiazoles, diamino type structures, and most recently pyridine structures. The expansion of these reactions has opened up new avenues of exploration and previously …

Characterizing The Role Of Chemo-Mechanical Couplings In The Activation Process Of Proteins That Undergo Conformational Changes, Ugochi Isu

Graduate Theses and Dissertations

Proteins are not static entities; rather, they are dynamic macromolecules that undergo conformational changes to perform their biological functions. These structural transitions are often coupled to chemical events such as lipid interactions, or changes in the cellular environment. Understanding the intricate interplay between chemical perturbations and the resulting mechanical response is crucial for elucidating the activation mechanisms of proteins. This dissertation aims to characterize the role of chemo-mechanical couplings in the activation process of two G protein-coupled receptors (GPCRs): Cannabinoid Receptor 1 (CB1) and Metabotropic Glutamate Receptor 1 (mGluR1). We employ molecular dynamics simulations to investigate the conformational landscapes of …

Derived Jet Schemes And Arc Spaces, And Arithmetic Arc Space Representability, C. Eric Overton-Walker

Graduate Theses and Dissertations

Associated to a given scheme X one can define geometric and arithmetic notions of jet schemes and arc spaces. We develop a construction of the geometric jets and arcs in the setting of derived schemes and explore consequences thereof. In particular, we prove an analogous theorem to that of one by Tommaso de Fernex and Roi Docampo concerning the cotangent sheaves of geometric jets and arcs. Our version then produces many subsequent results which allow us to prove stronger versions of results concerning geometric jets and arcs by removing unnecessary hypotheses. Separately, we explore evidence as to why, in contrast …

Geochemical Analysis Of Basement Rock As A Potential Metal Source In Mississippi Valley-Type Ores, Southern Midcontinent U.S.A., Mackenzie Margaret Moorhead

Graduate Theses and Dissertations

Mississippi Valley-Type (MVT) ores are epigenetic, sedimentary hydrothermal base metal deposits that exist worldwide with type localities in the midcontinent United States. These Permian-aged sulfide ores represent an extraordinary concentration of economic metals, Pb and Zn. Ore deposits occur in vast districts that have a rich mining history. The Pb and Zn from these deposits account for 24% of worldwide reserves. The geologic processes responsible for MVT ore genesis are not fully understood, especially the sourcing of ore constituents. In the midcontinent, the Ouachita Orogeny expelled saline hydrothermal brines in response to high rates of subsidence. These fluids migrated through …

Fabrication And Characterization Of Black Phosphorus Terahertz Photoconductive Antennae, Katie Michelle Welch

Graduate Theses and Dissertations

Advancements in terahertz (THz) imaging systems, particularly for applications like post-surgical analysis of breast cancer, have led to the exploration of novel materials such as black phosphorus as the active material for a THz photoconductive antenna (PCA). This thesis, motivated by innovative techniques developed at the University of Arkansas, investigates the potential of black phosphorus as a material to enhance the performance of THz PCAs, focusing on generation efficiency and bandwidth. Previous implementations of BP as THz emitters have shown limitations, highlighting the need for thorough material characterization and optimized fabrication processes. Therefore, we adopted a dual-phase approach to this …

Advancing Compact Modeling Of Electronic Devices: Machine Learning Approaches With Neural Networks, Mixture Density Networks, And Deep Symbolic Regression, Jack Robert Hutchins

Masters Theses

This thesis pioneers the integration of deep learning techniques into the realm of compact modeling, presenting three distinct approaches that enhance the precision, efficiency, and adaptability of compact models for electronic devices. The first method introduces a Generalized Multilayer Perception Compact Model, leveraging the function approximation capabilities of neural networks through a multilayer perception (MLP) framework. This approach utilizes hyperband tuning to optimize network hyperparameters, demonstrating its effectiveness on a HfOx memristor and establishing a versatile modeling strategy for both single-state and multistate devices.

The second approach explores the application of Mixture Density Networks (MDNs) to encapsulate the inherent stochasticity …

Evaluation Of Avian Use Of Agricultural Cover Crops During The Winter, Migration Stopover, And The Breeding Season In Tennessee, Brittany Panos

Masters Theses

The U.S. Department of Agriculture Natural Resources Conservation Service administers the cover crop program to provide technical and financial assistance to agricultural producers to sow herbaceous plant seeds to establish cover crops to protect agricultural fields from soil erosion during the non-growing season (late fall through spring). Soil retention and water quality benefits have been documented, but potential benefits for avian wildlife remain largely unknown. I used line-transect avian and vegetation surveys to examine use of cover crop fields by birds during the non-breeding period (winter), migration, and the breeding season. I compared avian use of cover crop fields with …

N-Methylation Of Amphetamine By Phenylethanolamine N- Methyltransferase: Implications For Chronic Therapeutic Use, Mackenzie Pavlik

Master's Theses

In current forensic analysis, the presence of methamphetamine in a sample is routinely presumed to reflect methamphetamine abuse. This is due to the expectation that individuals either abusing, or receiving amphetamine for therapeutic purposes (e.g. as treatment for ADHD) will not generate any significant levels of methamphetamine as a product of metabolism. We have hypothesized however, that because amphetamine can serve as a substrate for methylation by phenylethanolamine n-methyltransferase (PNMT), (which will be in equilibrium with the reverse demethylation reaction) some individuals chronically taking amphetamine for therapeutic purposes may generate low levels of methamphetamine that would show up on a …

Mathematical Modeling And Examination Into Existing And Emerging Parkinson’S Disease Treatments: Levodopa And Ketamine, Gabrielle Riddlemoser

Undergraduate Honors Theses

Parkinson’s disease (PD) is the second most common neurodegenerative disease across the world, affecting over 6 million people worldwide. This disorder is characterized by the progressive loss of dopaminergic neurons within the substantia nigra pars compacta (SNpc) due to the aggregation of α-synuclein within the brain. Patients with PD develop motor symptoms such as tremors, bradykinesia, and postural instability, as well as a host of non-motor symptoms such as behavioral changes, sleep difficulties, and fatigue. The reduction of dopamine within the brain is the primary cause of these symptoms. The main form of treatment for PD is levodopa, a precursor …

Enhancing Security And Usability In Password-Based Web Systems Through Standardized Authentication Interactions, Anuj Gautam

Doctoral Dissertations

Password-based authentication is the predominant method for securing access on the web, yet it is fraught with challenges due to the web’s lack of inherent design for authentication. Password managers have emerged as auxiliary tools to assist users in generating, storing, and inputting passwords more securely and efficiently. But both the browser and the server are oblivious of the password manager’s presence, leading to usability and security issues. However, because the web wasn’t originally built to accommodate password-based authentication, password managers serve as a temporary fix and encounter several usability and security problems that limit their widespread use. This dissertation …

Information Based Approach For Detecting Change Points In Inverse Gaussian Model With Applications, Alexis Anne Wallace

Electronic Theses, Projects, and Dissertations

Change point analysis is a method used to estimate the time point at which a change in the mean or variance of data occurs. It is widely used as changes appear in various datasets such as the stock market, temperature, and quality control, allowing statisticians to take appropriate measures to mitigate financial losses, operational disruptions, or other adverse impacts. In this thesis, we develop a change point detection procedure in the Inverse Gaussian (IG) model using the Modified Information Criterion (MIC). The IG distribution, originating as the distribution of the first passage time of Brownian motion with positive drift, offers …

Traffic Analysis Of Cities In San Bernardino County, Sai Kalyan Ayyagari

Electronic Theses, Projects, and Dissertations

This research offers an in-depth analysis of vehicular traffic within San Bernardino County, California, aiming to spotlight congestion areas and suggest improvements for more efficient and sustainable transportation. Leveraging 2021 data from StreetLight Data, traffic patterns in 15 key cities were examined based on their population sizes, covering various vehicle types to dissect dynamics and flow. The methodology focused on analyzing trip purposes and metrics to calculate Vehicle Miles Traveled (VMT) and its influence on congestion and environmental factors.

Findings indicate considerable disparities in traffic volume, purposes, and timings across different urban areas, with population density and intercity connections significantly …

Truck Traffic Analysis In The Inland Empire, Bhavik Khatri

Electronic Theses, Projects, and Dissertations

This study undertakes a meticulous examination of truck traffic within the Inland Empire, focusing on the distribution and dynamics of medium and heavy-duty vehicles, to advocate for the region's transition to electric trucks. Utilizing advanced spatial analysis and data from Streetlight Data, it segments the region into six subregions, revealing distinct traffic patterns and environmental impacts. Notably, the research uncovers that the North Center and West zones, integral to the logistics and warehousing sectors, exhibit the highest traffic volumes, significantly influencing air quality and infrastructure.

Quantitative results from 2021 illustrate a pronounced disparity in truck activity: medium-weight vehicles accounted for …

Artificial Intelligence's Ability To Detect Online Predators, Olatilewa Osifeso

Electronic Theses, Projects, and Dissertations

Online child predators pose a danger to children who use the Internet. Children fall victim to online predators at an alarming rate, based on the data from the National Center of Missing and Exploited Children. When making online profiles and joining websites, you only need a name, an email and a password without identity verification. Studies have shown that online predators use a variety of methods and tools to manipulate and exploit children, such as blackmail, coercion, flattery, and deception. These issues have created an opportunity for skilled online predators to have fewer obstacles when it comes to contacting and …

On Cheeger Constants Of Knots, Robert Lattimer

Electronic Theses, Projects, and Dissertations

In this thesis, we will look at finding bounds for the Cheeger constant of links. We will do this by analyzing an infinite family of links call two-bridge fully augmented links. In order to find a bound on the Cheeger constant, we will look for the Cheeger constant of the link’s crushtacean. We will use that Cheeger constant to give us insight on a good cut for the link itself, and use that cut to obtain a bound. This method gives us a constructive way to find an upper bound on the Cheeger constant of a two-bridge fully augmented link. …

Classification Of Remote Sensing Image Data Using Rsscn-7 Dataset, Satya Priya Challa

Electronic Theses, Projects, and Dissertations

A novel technique for remote sensing image scene classification is employed using the Compact Vision Transformer (CVT) architecture. This model strengthens the power of deep learning and self-attention algorithms to significantly intensify the accuracy and efficiency of scene classification in remote sensing imagery. Through extensive training and evaluation of the RSSCNN7 dataset, our CVT-based model has achieved an impressive accuracy rate of 87.46% on the original dataset. This remarkable result underscores the prospect of CVT models in the domain of remote sensing and underscores their applicability in real-world scenarios. Our report furnishes an elaborate account of the model's architecture, training …

An Empirical Study On The Efficacy Of Llm-Powered Chatbots In Basic Information Retrieval Tasks, Naja Faysal

Electronic Theses, Projects, and Dissertations

The rise of conversational user interfaces (CUIs) powered by large language models (LLMs) is transforming human-computer interaction. This study evaluates the efficacy of LLM-powered chatbots, trained on website data, compared to browsing websites for finding information about organizations across diverse sectors. A within-subjects experiment with 165 participants was conducted, involving similar information retrieval (IR) tasks using both websites (GUIs) and chatbots (CUIs). The research questions are: (Q1) Which interface helps users find information faster: LLM chatbots or websites? (Q2) Which interface helps users find more accurate information: LLM chatbots or websites?. The findings are: (Q1) Participants found information significantly faster …

Leveraging Blockchain Technology To Revamp The Vehicle Electrification Journey: Perspectives Of Accountability And Economic Circularity, Eva Escobar Brown

Electronic Theses, Projects, and Dissertations

The automotive industry is undergoing a significant transition accelerated by global emission regulations for a phase out of internal combustion engines (ICEs) and a transition toward the adoption of electric vehicles (EVs). While regulatory measures and incentivized adoption for EVs presents opportunities for reducing emissions and promoting sustainability, it also poses complex challenges. The EV industry faces potential production challenges, particularly in the sourcing, manufacturing, and lifecycle management of critical minerals and raw materials for electric vehicle batteries (EVBs). With a heavy reliance on a steady and diversified supply of critical minerals such as lithium, cobalt and rare earth elements, …

Crash Detecting System Using Deep Learning, Yogesh Reddy Muddam

Electronic Theses, Projects, and Dissertations

Accidents pose a significant risk to both individual and property safety, requiring effective detection and response systems. This work introduces an accident detection system using a convolutional neural network (CNN), which provides an impressive accuracy of 86.40%. Trained on diverse data sets of images and videos from various online sources, the model exhibits complex accident detection and classification and is known for its prowess in image classification and visualization.

CNN ensures better accident detection in various scenarios and road conditions. This example shows its adaptability to a real-world accident scenario and enhances its effectiveness in detecting early events. A key …

Grey Relational Analysis And Canonical Correlation Analysis Of Air Pollution In Three Kentucky Counties, Sarah Hartman

Masters Theses & Specialist Projects

Air pollution is a crucial factor that affects both the environment and public health. Various methods are available for assessing air quality and pollution levels, such as regression models, principal component analysis, and factor analysis tools. However, some of these methods present issues in multicollinearity and the nature of collected data. It is important to recognize that air pollution data is often uncertain, incomplete, and contains limited valid data points. Weather conditions and economic activities are also factors that can affect air pollution. With growing communities in Kentucky (KY), it is essential to address these factors as the state has …

Synthesis Of Gold Nanoparticles Via Pulsed Liquid Ablation For Use In The Photodynamic Therapy Of Bacteria, Justice Ben Yosef

Masters Theses & Specialist Projects

With the ever-increasing threat of antibiotic resistant bacteria, alternative treatment methods have been developed including photodynamic therapy (PDT). Within the PDT process, photosensitizers are used to generate reactive oxygen species (ROS) and facilitate the cell termination process. This work lays the conceptual foundation for the functionalization of the photosensitizer methylene blue (MB) with gold nanoparticles (AuNPs) and INF-55 as a potential inhibitor of the AcrAB-TolC efflux pump to enhance the effectivity of the PDT process.

AuNPs were synthesized using pulsed laser ablation in an aqueous citrate solution. Both nanosecond and picosecond pulse durations, as well as both 532 nm and …

Process Modeling The Neuroprotective Effects Of A Plant-Based Diet On Parkinson's Disease, Julia Mitchell

Undergraduate Honors Theses

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by motor symptoms such as tremors, bradykinesia, rigidity, and postural instability. Recent research suggests an avenue for potential neuroprotection through dietary intervention, specifically the adoption of a plant-based diet. A plant-based diet predominantly comprises foods derived from plants, emphasizing fruits, vegetables, grains, legumes, and nuts while minimizing or excluding animal products. This thesis aims to explore the biochemical pathways implicated in PD progression and the potential impact of dietary choices on these pathways. The investigation focuses on several key pathways: alpha-synuclein aggregation, the blood-brain barrier crossing of levodopa, oxidative stress, ferroptosis, …