Physical Sciences and Mathematics Commons^™

Extreme Precipitation Events And Population Exposure: Site Recommendations For The Future Tennessee Mesonet, Victoria G. Redlund

Electronic Theses and Dissertations

This study examines frequency of and population exposure to extreme rainfall events in Tennessee to guide the placement of future mesonet weather stations. Using 1991-2021 daily nClimGrid precipitation records, extreme events were defined as events of rainfall ≥50 mm. These events were collated on an annual scale and normalized alongside square-root-scaled population densities derived from Landscan to develop extreme rainfall vulnerability maps. Results highlight where extreme rainfall is most frequent relative to population densities in each county. The findings were compared with models of mesonet suitability and feasibility to determine how meteorological needs correlate with siting needs such as land …

Ontogeny And The Effects Of Perinatal Stress In The First Immature Skeleton Of Teleoceras Aepysoma (Perissodactyla, Rhinocerotidae), Joe Gajewski

Electronic Theses and Dissertations

Recovery of an immature fossil rhinoceros (Teleoceras aepysoma) skeleton (ETMNH 32999) from the Gray Fossil Site in Tennessee offers the first insights into the ontogeny of the species. ETMNH 32999 is interpreted to be a subadult male in an age class equivalent to ~17-20% of potential lifespan. Comparative analyses support the hypothesis that subadults of related taxa are typically ~91% of average adult size in most dimensions. However, certain cranial dimensions are substantially lower than expected in ETMNH 32999, averaging only ~74% of the average conspecific adult. Such departure from typical growth rates is suggested to be attributable …

Utilizing Physics Informed Neural Networks For Disrupted Signal Dynamics, Nicholas J. Joyner

Electronic Theses and Dissertations

Physics-informed neural networks (PINNs) have been used in many applications including engineering and physical sciences. PINNs allow the incorporation of a priori understanding of a process’ structure into the modeling. We attempt to leverage the PINN structure toward the evaluation of disruptions to classical dynamical models by combining elements of ordinary differential equations into our loss function with sigmoidal gating to balance the penalties for deviations from the data with those for structural deviations. This enables the identification of the signal structure and the limits of disruption influence. As a use case, we consider stock value from 2019-2021, which expresses …

Mechanism Of Formation Of Guanine-Guanine Crosslinks As Products Of One-Electron Oxidation Of 1-Methylguanosine In Acidic Medium, Ibrahim Braimah Mr

Electronic Theses and Dissertations

Reactive oxygen species (ROS) from normal metabolism and environmental exposure may cause oxidative DNA damage. Guanine (G) is the most oxidizable nucleobase. One-electron oxidation (OEO) of G in produces guanine radical cation (G•⁺), which deprotonates to form guanyl radical G(-H)•.This radical exists in two tautomeric forms: G(N1-H)• and G(N2-H)•. Dimerization of guanyl radical yields G-G cross-links (D1/D2); a tautomeric form for dimer formation remains elusive. This study presents the first characterization of G• dimerization products from the OEO of 1-MeGuo in acidic medium. Photolysis at 470 nm in the presence of S₂O₈²⁻ and Ru(II)(bpy)₃²⁺ generates two major stereoisomers (D1AW* and …

Durable, Distributed Llm Inference On Cots Devices, Brycen E. Dunn

Electronic Theses and Dissertations

The advancement of Large Language Models (LLMs) has fundamentally changed the nature of natural language processing. The substantial memory requirements of frontier models creates a significant barrier to entry, centralizing inference. This thesis presents the design and implementation of a distributed inference framework designed to democratize LLMs by leveraging commodity devices. The framework combines the resources of heterogeneous COTS devices into a unified compute pool, enabling the inference of models exceeding a single device's memory capacity. A novel Task Partitioning Engine (TPE) analyzes model architectures, profiles node capabilities, and supports pipeline and expert parallelism strategies. The primary contribution is a …

Integrated Geophysical, Geotechnical, And Mineralogical Characterization Of Expansive Weches Formation Soils In East Texas: Implications For Infrastructure Design, Samuel Annobil

Electronic Theses and Dissertations

This study investigates the geotechnical, geophysical, and mineralogical characteristics of soils derived from the Weches Formation in Nacogdoches County, East Texas, with emphasis on the relationships among electrical resistivity, moisture condition, compaction state, and mineralogical composition. The Weches Formation is well known for producing clay-rich, moisture-sensitive soils that pose challenges to subgrade performance because of their plasticity and swelling behavior. Representative soil samples were collected and subjected to laboratory testing, including particle size analysis, Atterberg limits, Standard Proctor compaction, free swell tests, electrical resistivity measurements, and X-ray diffraction (XRD) mineralogical analysis. The soils are predominantly fine-grained and clay-rich, with USCS …

Stability Of Paraffin-Insulated Nitrogen-Doped Carbon Fiber Ultramicroelectrodes, Maxwell H. Kwakwah

Electronic Theses and Dissertations

Nitrogen-doped carbon materials can facilitate the reduction oxygen-oxygen bonds, a key step in electroreduction of both O₂ (an important reaction in energy applications) and H₂O₂ (an important reaction in sensing and biosensing). Our lab previously demonstrated that thermal decomposition of urea in the presence of carbon fiber (CF) results in an N-doped carbon material that exhibits good electrocatalytic properties for H₂O₂ reduction. However, previous methods of insulating single N-doped CF via laser heating of borosilicate capillaries and epoxy to prepare ultramicroelectrodes (UMEs) seemed to adversely affect surface nitrogen contents and electrocatalytic properties. More recent work that utilized paraffin to …

Discrete-Event Simulation: A Leslie System Model For Transportation Demography, Md Zobaer Ahammad

Electronic Theses and Dissertations

Transportation systems are influenced by demographic change, household formation,and patterns of vehicle ownership. These factors affect long-run transportation demand and congestion levels within urban infrastructure. Understanding how demographic dynamics interact with transportation behavior is therefore important for analyzing the long-term evolution of transportation systems. This thesis develops a modeling framework that integrates discrete-event simulation with a Leslie-type matrix model to study transportation–demography interactions.Simulation outputs are aggregated to construct a transition matrix describing changes in transportation states. This matrix acts as a linear (or affine) transformation on the transportation state vector, allowing the system to be analyzed as a discrete linear …

Machine-Learning Landslide Susceptibility And Runout Modeling In The Nolichucky River Gorge After Hurricane Helene, Grace Braver

Electronic Theses and Dissertations

Extreme rainfall from Hurricane Helene (September 2024) triggered widespread landslides across the southern Appalachian region, highlighting the need for rapid landslide susceptibility assessments that capture both landslide initiation and downstream runout. Traditional susceptibility models often focus solely on initiation zones, limiting their ability to identify which slopes will generate destructive landslides or where material will travel. This study addresses that gap by (1) integrating Geographic Information System (GIS)-based machine learning susceptibility modeling using ArcGIS Pro: Maximum Entropy (MaxEnt) and Random Forest-Based and Boosted Classification and Regression (FBBC) and (2) the U.S. Geological Survey (USGS) Grfin (Growth, Flow, and Inundation) runout …

Addressing The Problems Of Data Variations, Quality, And Scarcity In Training Deep Neural Networks, Jian Sun

Electronic Theses and Dissertations

The performance of deep neural networks (DNNs) is strongly influenced by the characteristics and quality of the underlying datasets. This Ph.D. dissertation addresses three pervasive data challenges-imbalance, quality degradation, and scarcity-that commonly hinder the effectiveness of DNNs in computer vision (CV) and natural language processing (NLP) applications.

Class imbalance remains one of the most frequent causes of degraded model generalization. While Focal Loss effectively mitigates inter-class imbalance by assigning higher weights to minority classes, it struggles with intra-class imbalance, particularly in video datasets where longer clips dominate feature representation. To address this, I implement and utilize …

Development And Application Of Lc-Ms/Ms Methods For The Determination Of Environmental Contaminants, Mawuli Wilson-Cee Macdonald

Electronic Theses and Dissertations

Environmental contaminants such as neonicotinoids and bisphenols are increasingly detected at ultratrace concentrations in environmental and consumer matrices, necessitating sensitive and efficient analytical methodologies. This dissertation presents the development, validation, and application of liquid chromatography–tandem mass spectrometry (LC–MS/MS) methods coupled with simplified sample preparation techniques. In Chapter 2, a direct aqueous injection (DAI) LC–MS/MS method was developed for the analysis of five neonicotinoids in surface water, eliminating extensive sample preparation. The method demonstrated strong linearity (R² = 0.993–0.998), with limits of detection (LOD) ranging from 0.5 to 4 ng/L and lower limits of quantification (LLOQ) of 10–50 ng/L. Accuracy (80–120%) …

Floodwater Salinity And Flood Duration Regulate Greenhouse Gas Production In High- Latitude Coastal Wetland And Tundra Soils, Mia J. Dicianna

Electronic Theses and Dissertations

Coastal high-latitude ecosystems are increasingly flooded from storm surges associated with climate change, exposing soils that were historically infrequently inundated to higher-salinity waters for longer durations. Sub-Arctic wetlands and tundra store large amounts of carbon, yet how flooding characteristics, particularly flood duration, influence microbial mineralization and, consequently, greenhouse gas (GHG) production in these soils remains poorly understood. We conducted a full-factorial microcosm incubation experiment in which coastal wetland and tundra soils were subjected to simulated flooding with three durations (1, 3, and 10 days) and four salinity treatments (unflooded, freshwater, 3 ppt, and 12 ppt) and measured carbon dioxide (CO2) …

Impacts Of Management Practices And Soil Properties On Free-Living Nitrogen Fixation In Eastern South Dakota, Laura Galvan Nuevo

Electronic Theses and Dissertations

Free-living nitrogen (N) fixation (FLNF) may represent a sustainable pathway to supplement crop N demand in agroecosystems, yet edaphic and management factors regulating this process under field conditions remain poorly understood in the Northern Great Plains. Using 15N2 direct method to quantify potential FLNF (pFLNF) and baseline FLNF (bFLNF), this thesis investigates how crop rotations (2-, 3-, and 4-year systems), tillage management (conventional vs. no-till), cover cropping, and soil properties affect the potential of free-living diazotrophs to supply N via FLNF in a long-term no-till corn-based system in Southeastern South Dakota. A two-year field study evaluated pFLNF across four growing …

Evaluating Planting Methods For Native Seed Production And Exploring Granivory In The Northern Great Plains, Allison Dollen

Electronic Theses and Dissertations

Temperate grasslands have faced immense losses due to land use change in the last 150 years and less than half of the overall grasslands that once covered North America remain today. A portion of historic and remaining U.S. grasslands are located within the northern Great Plains (NGP) region which is home to over 1,600 species of native plants and provides many ecosystem services and economic benefits. Initiatives to restore grasslands and their ecosystem services are currently underway, but barriers such as limited native seed supply and granivory hinder restoration efforts. My first chapter addresses knowledge gaps in planting methods for …

Improving Human Dimensions Of Conservation Planning: Challenges And Opportunities For Sustainable Conservation Outcomes, Vivian Hulugh

Electronic Theses and Dissertations

Conservation planning is important to ensure both ecological and social benefits of natural resources, including the maintenance of functional ecosystems and stable wildlife populations as well as the provision of resources that communities rely on. Yet, the integration of the human dimensions of conservation planning remains limited in practice. This thesis examines conservation planning in South Dakota and within Joint Venture (JV) partnerships, using qualitative methods to identify challenges and opportunities for more effective and coordinated planning. In chapter one, I examine how collaboration, public participation, and the use of climate information are integrated conservation planning in South Dakota and …

The Spacetime Finite Element Method For Investigations Into Physics Ghost Systems And Time Parallel Preconditioning, Jax Wysong

Electronic Theses and Dissertations

This work operates on two fronts, focusing on interesting physical phenomena before turning our attention to an interesting numerical math problem. First, using the spacetime finite element method (FEM), we investigate a PDE system consisting of two Klein Gordon equations, which are coupled nonlinearly through the potential energy. The system contains a ghost (negative kinetic energy term). Systems such as these are generally deemed physically unstable, resulting in infinite energy in finite time. However, recent work has shown that this is not always the case. We investigate multiple scenarios arising from different initial conditions to characterize if/when a ghost system …

Chemical Load: An Unseen Herbicide Filter In Restored Prairies?, Rylie Franklin

Electronic Theses and Dissertations

Community Assembly Theory is a framework used to describe the process by which species from a regional species pool disperse and encounter various abiotic and biotic conditions that act as filters, limiting which species will populate a specific local community. Prairie restoration success can be improved by understanding abiotic and biotic filters. As agricultural practices have adopted integrated weed management plans, that include the use of both chemical and non-chemical techniques, another filter needs to be considered during restoration: the chemical load of soils, i.e., herbicide residue from recent on-site applications and herbicide drift from adjacent areas. To examine the …

Discovery Of The Multi-Ion Bridge Intermediate: A Computational Exploration Of The Mechanism For Azomethine Ylide Formation From N-Oxides, Martin J. Neal

Electronic Theses and Dissertations

Density functional theory (DFT) provides a method for calculating the ground-state energies of complex molecular systems through evaluating the electron density instead of the full wave function. When results match either experimental outcomes, calculations with DFT offer a computationally efficient method to help explain chemical phenomena. The transformation of tertiary amine N-oxides to azomethine ylides, a simple route to the precursor for 1,3-dipolar cycloadditions that result in the pyrrolidine scaffolds found in natural products, has received only minimal attention due to concerns that its mechanism includes a highly electrophilic intermediate. Utilizing DFT to model the mechanism of the conversion …

A Sedimentary Source Of Rare Earth Elements In The North Atlantic, Rylee D. Lindner

Electronic Theses and Dissertations

Individually and as a series, the Rare Earth Elements (REEs) are powerful geochemical tracers of environmental processes. However, ambiguities in the oceanic budgets of the REEs hamper their application. Growing evidence suggests a sedimentary benthic flux via the pore water is the major source of REEs to the ocean, with extrapolated estimates of this flux being equivalent in magnitude to that “missing” from modern budgets. However, existing pore water REE data are available from only a few locations globally with no representative dataset from the open North Atlantic. This data scarcity limits our ability to constrain flux estimates and understand …

Thermal And Non-Thermal Mass Transport Effects In Plasmon-Assisted Electrochemistry., Md Al Amin

Electronic Theses and Dissertations

Plasmon-assisted electrochemistry has received attention due to its effects of hot charge carriers, photothermal heating, and enhanced electromagnetic field impact on electrochemical transformation. These effects have contributed to lowering the onset potential and increasing the reaction kinetics. Numerous studies have been employed to differentiate the effect of photothermal heating from hot charge carriers on the electrochemical reaction. Most of these studies have been employed to measure and quantify the photothermal heating effects at equilibrium temperature; however, localized heating from the incident light does not result in homogeneous heating across the electrochemical cell. Many studies investigating the photothermal heating effect in …

A Persistent Homology Framework For Scrna-Seq: Assessing Clustering Robustness And Quantifying Preprocessing And Integration Effects On Topological Features., Jonah Daneshmand

Electronic Theses and Dissertations

As single-cell RNA sequencing (scRNA-seq) data expands, robust methods for integrating diverse datasets are critical. This dissertation applies Persistent Homology (PH), a technique from Topological Data Analysis (TDA), to a collection of scRNA-seq datasets spanning eight tissue types to quantify how data integration affects topological features and biological interpretability. We assessed global topological structure using Betti curves, Euler characteristics, and persistence landscapes across raw, normalized, and integrated data representations. Our analysis revealed a performance inversion: while conventional methods excelled on unintegrated data, high-granularity topological methods, particularly those sensitive to global data structure, became superior after integration. This suggests a synergy …

Direct And Satellite-Based Quantification Of Greenhouse Gas Fluxes In Small Ponds., Mark Christopher Tierney

Electronic Theses and Dissertations

As evidenced by their historic losses due to anthropogenic activities, wetlands are undervalued ecosystems that provide numerous ecosystem services, from recreational opportunities to carbon (C) storage. However, these wetlands are also the largest natural source of atmospheric methane (CH₄). Additionally, small water bodies (< 10,000 m²) are disproportionately large emitters relative to larger lakes and reservoirs. As construction and restoration efforts proceed, it is crucial to identify wetlands that need restoration and to understand the factors driving both greenhouse gas (GHG) fluxes and the C balance of these systems. This dissertation investigates the drivers of greenhouse gas fluxes …

Synthesis, Characterization, And Chemical Reactivity Of Calcium-Alginate Hydrogel Beads Containing Metal Nanoparticles And Nanoclusters., Rajiv Kumar Singh

Electronic Theses and Dissertations

This dissertation explores the synthesis, stability, and reactivity of various metal nanoparticles (NPs) and nanoclusters (NCs) of varied size and stabilizers contained within millimeter-sized calcium alginate (Ca-Alg) hydrogel polymer beads. Hydrogel beads synthesized by combining sodium alginate with Au or Ag NPs stabilized with trisodium citrate (Cit) and adding dropwise into a 4.0 M Ca²⁺ solution remained stable and contained within the beads. Those synthesized Au, Pd and AuPd NCs stabilized with glutathione (SG) became partially released from the hydrogel within a day. The synthesis of beads containing aggregated Cit Au NPs occurs by inducing aggregation with tetrakis(hydroxymethyl) phosphonium …

Synthesis Of Phenyl-Substituted Zinc Dipyrrin Photosensitizer For Carbon Dioxide Reduction, Stephen Ankomah

Electronic Theses and Dissertations

The release of CO₂ from fossil fuel combustion drives the need for its conversion into more sustainable options like CO and CH₄ via photocatalytic reduction. This process requires a catalyst, sensitizer, and electron donor. Zinc dipyrrin-based complexes are promising photosensitizers, offering an alternative to expensive, rare-metal-based systems. Most first-row transition metal dipyrrin compounds have short excited-state lifetimes due to rapid nonradiative decay, but Zn(II) dipyrrin complexes stand out. With a d¹⁰ configuration, they lack deactivating ligand field states and can access long-lived triplet states through a charge-separated intermediate. A phenyl-substituted Zn(II) dipyrrin complex was synthesized and studied using NMR to …

Divergent Responses Of Branched-Chain And Straight-Chain Lipid Membranes To Butanol Stress Revealed By All-Atom Molecular Dynamics Simulations, Joshua Olaf Aggrey

Electronic Theses and Dissertations

Membrane integrity under chemical stress is critical to cellular survival and industrial microbial bioproduction, yet the molecular basis of bilayer resilience remains poorly understood. Using all-atom molecular dynamics simulation, we compare the effect of increasing concentrations of 1‑butanol on membranes composed of straight-chain (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC) and branched-chain (1-anteiso-palmitoyl-2-palmitoyl-sn-glycero-3-phosphocholine, APPC) lipids, which differ in the point of attachment of a single methyl group. In the absence of butanol, both membranes exhibit well-ordered architectures consistent with experimental benchmarks; however, under increasing solvent stress, their behaviors diverge markedly. DPPC membranes display gradual thinning, modest area per lipid …

Floodplain Lake Hydrodynamic And Morphodynamic Connections Through Hydraulic Modeling Along The Pee Dee River, Sc, Charles Cj Mina

Electronic Theses and Dissertations

Rivers have been essential in the success of humankind. This reliance has created a vested interest in studying the rivers' environmental history through using floodplain deposits, with the assumption that coarser sediments correlate to higher discharge floods. However, shifting hydrological connectivity and hydrodynamics can complicate this correlation in primary repositories of flood deposits, oxbow lakes, by altering the texture of sediments delivered to them. Studying these complications is essential for quantifying paleoflood magnitude using the sediment record, but has been difficult, as the currently used index of hydrological connectivity relies on water stage, which does not reflect the sediment flux …

The Food Truck: A Multi-Product Newsvendor With Expectile Risk, Sekyiwaah Nuamah

Electronic Theses and Dissertations

The Newsvendor Problem is a fundamental model in Operation Research and Supply Chain Management used to determine the optimal order quantity under uncertain demand to minimize expected costs.
This research extends the classical Newsvendor problem to a multi--product setting, addressing the risk of asymmetric cost structures faced by a food truck. This thesis introduces expectile risk measures to quantify and manage uncertainty in demand, moving beyond traditional risk metrics. To evaluate the impact of expectile-based decision-making, we analyze three types of demand distributions--simple, symmetric, and skewed. For skewed distributions, we apply linear spline inverse interpolation to derive expectile values from …

Stochastic Functional Data-Driven Models For Real-Time Battery Health Forecasting Under Dynamic Operating Conditions, Joshua Owusu

Electronic Theses and Dissertations

This thesis provides an effective statistical model to predict the real-time state of lithium-ion batteries for reliable Battery Management Systems (BMS). It highlights battery data (voltage, current, temperature) as smooth functional curves. The principal method demonstrates diminishing trends to health outcomes like State of Health (SoH) and Remaining Useful Life (RUL) by employing Functional Principal Component Analysis (FPCA) and Bayesian Functional Linear Models (FLMs). The primary objective is to figure out how uncertain forecasts are. Simulations demonstrate that the highest accuracy (lowest MSE) is achieved through low noise levels along with large sample sizes. The final system provides a highly …

Topic Modeling And Culturomic Analysis Of 30,000 Books Over 100 Years Using Gensim, Michael A. Freeman

Electronic Theses and Dissertations

This thesis explores the cultural influence of historical events on English-language fiction published between 1820 and 1929. Using a corpus of 30,256 digitized books from Project Gutenberg, Latent Dirichlet Allocation (LDA) topic modeling was applied to identify recurring themes across eleven decades. The study sought to determine whether historically significant events could be detected within fictional narratives. One clear instance emerged: Napoleon Bonaparte and the Napoleonic Wars appeared explicitly in the 1820s corpus. Beyond this, several thematic patterns were observed—such as maritime language in the 1840s, national identity in the 1880s, and youth-oriented dialogue in the early 20th century—that plausibly …

Geochemical Analysis Of The Eagle Ford Shale In Webb And Dimmit Counties, Tx, Natalie G. Girlinghouse

Electronic Theses and Dissertations

The Late Cretaceous Eagle Ford Shale of South Texas is a mixed carbonate–siliciclastic succession that serves as both a prolific hydrocarbon source and reservoir. This study integrates chemostratigraphy, mineralogical analysis, and elemental ratio proxies to reconstruct depositional environments and assess controls on detrital influx, paleoproductivity, and redox conditions across multiple cores in Webb and Dimmit counties. Major, trace, and redox-sensitive elements were evaluated alongside Total Organic Content (TOC) and carbonate content to identify stratigraphic trends and environmental shifts.

Results reveal distinct geochemical signatures between the Upper and Lower Eagle Ford Shale, with the Lower Eagle Ford characterized by elevated Al-rich …