Physical Sciences and Mathematics Commons^™

Motor Imagery Eeg Decoding For Brain-Computer Interfaces: Structured Representation, Transfer, And Drift, Yiming Shen

Graduate Doctoral Dissertations

Motor imagery EEG decoding is often summarized by the accuracy of a final classifier, but the classifier is only the last stage of the pipeline. Before classification, the signal has already been shaped by preprocessing, feature extraction, source-session organization, and adaptation. This dissertation studies how feature representation, source-session transfer, and drift shape reliable MI-EEG decoding for brain-computer interfaces.

It first studies within-session decoding on public MI-EEG datasets using nested validation that keeps preprocessing, feature fitting, and model selection inside the training folds. This analysis separates gains from feature representation from gains due to nonlinear classification, and relates both comparisons to …

The Grasshopper's Journey To The Bloch Sphere, David Llamas

Graduate Doctoral Dissertations

The Grasshopper Problem asks a simple geometric question. A grasshopper lands on a lawn of fixed area and jumps a fixed distance in a random direction. What shape of lawn maximizes the probability that the grasshopper remains on the lawn after jumping? The jump rule is rotationally symmetric, but the best lawns do not have to be. This dissertation studies how that symmetry breaking occurs, maps the continuum problem to a novel constrained spin system, and uses the spherical Grasshopper Problem to compare quantum singlet correlations with classical local models.

For planar lawns, boundary-integral and perturbative calculations explain why the …

Redesigning Quantum Theory, Matthew Weiss

Graduate Doctoral Dissertations

QBism understands quantum mechanics to be probability theory supplemented by additional nonclassical coherence conditions. In this dissertation, we develop these nonclassical coherence conditions from first principles, emphasizing the role of a well chosen reference measurement. After treating standard probability on subjective Bayesian lines, we demonstrate an equivalence between the QBist approach and the existing framework of generalized probabilistic theories. We show that the fundamental nonclassical coherence relation may almost always be taken to be a gentle modification of the law of total probability, and give a coherentist account of when an experimental scenario has a classical explanation. Finally, we show …

A Statistical Mechanics Approach To Reinforcement Learning, Jacob Adamczyk

Graduate Doctoral Dissertations

Reinforcement learning (RL), the study of optimal decision-making over long timescales in stochastic systems, has recently seen remarkable advances due in large part to the efforts of the deep learning community. RL has witnessed great success in solving problems in video games, robotics, biological control, and language modeling. However, a unified statistical mechanics framework to understand and develop the corresponding algorithms is lacking. To address this issue, we begin by showing that the reinforcement learning problem can be formulated and solved using the tools of statistical mechanics. Drawing on physical principles of free energy minimization and invariance, we address important …

Multicomponent Reaction-Initiated Synthesis Of Polyheterocyclic Compounds, Ashutosh Nath

Graduate Doctoral Dissertations

Efficient synthesis of novel heterocycles with biological interest remains a challenge in modern organic chemistry. This dissertation presents the development of efficient synthetic strategies that combine multicomponent reactions (MCRs) with sequential reactions for rapid access a diverse array of polyheterocyclic compounds. The projects are: 1) Groebke-Blackburn-Bienaymé (GBB) reaction followed by N-acylation and Friedel-Crafts (FC) cyclization for the construction of imidazopyridine- and indole-fused azepinones involving an unusual ring-expansion process. 2) Modified GBB condensation products for intramolecular Diels-Alder (IMDA) cycloaddition and dehydrative re-aromatization to access imidazopyridine-fused isoquinolinones. 3) Integration of the Ugi-three component reaction (Ugi-3CR) and Pictet-Spengler (PS) reaction followed by …

Dynamics Of Swimming Microorganisms At Structured Liquid Crystal Interfaces, Vajra Sabhapathy Badha

Graduate Doctoral Dissertations

Active matter systems are self-driven units that consume energy to generate motion and mechanical stresses, producing non-equilibrium states of broad physical significance. Examples include synthetic microswimmers and migrating cells. Motile bacteria are a widely studied biological example because their self-propelled motion, hydrodynamic interactions, and collective organization are strongly coupled to local environmental conditions. Their swimming is sensitive to interfacial viscoelasticity, ordering, confinement, and hydrodynamic boundary effects, making them useful for investigating how interfaces regulate active biological motion. Because bacterial accumulation and attachment at interfaces are central to colonization and biofilm formation, these interactions are relevant to both active matter physics …

Enterococcus Abundance, Distribution, And Environmental Controls At A Sandy Shoreline, South Carolina, Usa, Helen Kehoe

Electronic Theses and Dissertations

Water quality monitoring crucially protects the health of beachgoers around the world. However, water-adjacent sediments, such as sandy beaches, are known to harbor harmful bacteria, yet are not monitored despite their intensive recreational use. This project monitored the abundance of fecal indicator bacteria (FIB), specifically Enterococci, in sandy beach sediments at beaches routinely monitored for water quality in Myrtle Beach and North Myrtle Beach, South Carolina. Surface sediment core sampling (0-5 cm) in the swash zone was conducted once per month for 4 months at 24 beaches in tandem with state-accredited surf-water FIB monitoring using IDEXX’s Enterolert test (Standard Method …

Spatial Variation In Resource Use And Species-Level Trophic Niches Of White And Brown Shrimp In North Inlet–Winyah Bay, South Carolina, Josie Bryan

Electronic Theses and Dissertations

Atlantic white (Penaeus setiferus) and brown shrimp (Penaeus aztecus) are ecologically and economically important species in the southeastern United States, supporting coastal food webs and valuable commercial fisheries. To understand their trophic dynamics in the North Inlet-Winyah Bay estuary, we conducted a spatial and temporal analysis using carbon (δ¹³C), nitrogen (δ¹⁵N), and sulfur (δ³⁴S) stable isotopes to evaluate trophic position and basal source contributions across three habitat types (river, bay, and marsh). Linear models were used to evaluate the effects of size (rostrum–carapace length, RCL, in mm), habitat, and species on trophic position, as well as the effects of habitat …

Comparison Of River Plume Classification Methods Using In-Situ Data, Payton Merica

Electronic Theses and Dissertations

River plumes transport terrigenous materials into the ocean, such as nutrients, pollutants, or sediment. These plumes can be separated into regions, including the source region, near-field, mid-field, and far-field, historically defined broadly by the governing forces in each region. Existing methods for classifying these plume regions are limited and often only take into account a subset of influencing factors. This study seeks to compare prior plume region classification methods, such as the Froude number and Rossby radius of deformation, to dominant dynamics within each region using momentum scaling proposed by Garvine (1995). Comparisons were derived from observational data collected during …

Long-Term Trends And Drivers Of Commercial Shrimp Fisheries Across The Southeastern U.S. Atlantic Coast, Trinity Assels

Electronic Theses and Dissertations

Long-term dynamics of southeastern U.S. Atlantic commercial shrimp fisheries reflect interacting environmental and socioeconomic processes rather than uniform regional decline. However, integrated, multi-state assessments linking these drivers to fishery-dependent indicators remain limited for the region. This study analyzed over four decades (1980–2023) of confidential fishery-dependent data from coastal South Carolina, Georgia, and northeastern Florida, focusing on the region where white and brown shrimp dominate commercial landings. Segmented regression analysis was used to identify structural shifts in long-term trends of landings, participation, and catch-per-unit-effort (CPUE), while multiple linear regression models identified seasonal temperature variables associated with interannual variation in shrimp CPUE. …

Presence And Impact Of Herbicides On Intertidal Benthic Communities, Marco Sanderson

Electronic Theses and Dissertations

The growing reliance and widespread use of herbicides on a global scale is negatively affecting non-targeted biota and, consequently, their ecosystems. Herbicide levels and their impacts have been extensively researched around the world in riverine and lacustrine ecosystems. However, studies of the levels and effects of herbicides on coastal intertidal benthic communities have been lacking. This study focused on testing spectrophotometric methodologies for herbicides (atrazine and glyphosate) and documenting their presence and levels in sediment, water, and biotic tissue of intertidal coastal beaches and marshes of Waties Island and Singleton Swash, Horry County, South Carolina. A laboratory microcosm was employed …

Fabrication Of Objectives For Imaging Ultracold Lithium, Danelle Akanova

Dartmouth College Master’s Theses

This thesis develops a documented, reproducible procedure for building diffraction-limited microscope objectives entirely from catalog singlets, for imaging ultracold 6Li atoms in a ring-trap experiment. The objectives must resolve micron-scale features through a 5 mm fused-silica vacuum window, operate at multiple wavelengths, fit inside a 48 mm magnet bore, and contain no conductive or magnetic material, because the surrounding coils switch 0.1 T fields on microsecond timescales. Commercial long-working-distance objectives are universally housed in metal, which the eddy-current constraint rules out, and custom fabrication of a suitable non-conductive matched pair is estimated at nearly $200k.

The procedure is developed and …

Development Of Quantum Cryptographic Algorithm For Next Generation Secure Systems, Gururaja Ts Mr

Theses and Dissertations

The rapid advancement of digital communication and quantum technologies are developing at an accelerated pace makes cybersecurity and data protection a big challenge. The traditional cryptographic methods are increasingly under attack by phishing, brute force, cryptanalytic attack and threats of quantum computing. This research presents a quantum-secure communication based on Quantum Random Number Generator (QRNG), Quantum Key Distribution (QKD), Quantum Image Encryption (QIE) and secure quantum key access using a dongle-based hardware.

QRNG models were designed in the quantum simulator and hardware. The sequences produce high entropy and they passed the statistical randomness tests with p-values higher than 0.01 indicates …

Correlative In Situ Nonlinear Optical Characteriztion Of Plasmonic Colloidal Nanoparticle Growth Dynamics, Stena C. Peterson

LSU Doctoral Dissertations

Colloidal noble metal nanoparticles are of extreme interest as nanomaterials and for the wide variety of their possible applications in nanomedicine. The unique linear and nonlinear optical processes associated with these nanomaterials can be studied using a variety of spectroscopic techniques including extinction, second harmonic generation (SHG), and two-photon fluorescence (TPF) spectroscopy. In order to better understand and optimize these nanomaterials for their desired applications, it is important to investigate the growth and photophysical dynamics associated with gold nanoparticles, silver-gold core-shell (Ag-Au CS) nanoparticles, and gold-silver-gold core-shell-shell (Au-Ag-Au CSS) nanoparticles in addition to how their size, surface morphology, composition. and …

Molecular Interactions Of The Gas–Solid Interface: Svocs On Swelling Clays And San Joaquin Soil Surfaces, Liesl T. Jensen

Electronic Theses and Dissertations

Soil-derived mineral dust plays an important role in atmospheric chemistry by acting as a reactive interface for gas–particle interactions that influence the fate and transport of organic contaminants. Among soil components, clay minerals dominate surface reactivity due to their high surface area, structural complexity, and the presence of chemically active sites arising from cation exchange capacity and surface acidity. Environmental conditions, particularly relative humidity, further regulate these interactions by altering surface accessibility and competitive adsorption processes.

Despite the recognized importance of mineral dust, gas-phase interactions between organic compounds and clay minerals remain insufficiently understood, particularly under atmospherically relevant conditions. This …

Compact 1 Ghz Electron Paramagnetic Resonance Spectrometers For Preclinical Imaging Studies, Tanden A. Hovey

Electronic Theses and Dissertations

Magnetic resonance is one of the most generally useful scientific techniques. New horizons of understanding are revealed as technological advances make possible explorations of nuclear spins and electron spins at higher and lower magnetic fields and electromagnetic frequencies. While the greatest current effort is on ever higher magnetic fields and microwave frequencies, both in nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR), the Eaton lab focusses on developing high signal-to-noise performance EPR at low microwave frequencies. EPR provides information about O2, pH, viscosity, glutathione concentrations, and reactive oxygen species in living organisms that MRI cannot. To yield clinically or …

Three-Dimensional Cell And Nuclear Geometries Inform Tissue Level Fluid Mechanics During Epithelial Remodeling, Liam Joseph Russell

Electronic Theses and Dissertations

During epithelial remodeling, mechanical and molecular programs must coordinate to drive the cell shape changes that enable new tissue topologies. Dynamic morphogenesis requires epithelia to preferentially exhibit solid- or fluidlike properties depending on developmental and biophysical constraints. Convergent extension in the Drosophila germband epithelium is one such remodeling event, during which the lateral ectoderm lengthens by two-fold along the primary body axis while concomitantly shortening orthogonally. This process is an incredibly dynamic and attractable system for studying tissue morphogenesis mechanics in vivo.

Germband extension is driven by oriented cell intercalation through T1 transitions, where cells directionally interdigitate with one another …

Field-Like- And Self-Spin-Orbit Torques In Magnetic Multilayer Films, Kyle Jeffrey Peterson

Electronic Theses and Dissertations

Spin-orbit torques (SOTs) have been realized as an energy efficient mechanism to manipulate and drive magnetization dynamics in magnetic multilayer films. Their damping-like and field-like components provide distinct pathways for controlling the magnetization, enabling switching, sustaining magneto-oscillations, and driving domain-wall motion with potential applications in nonvolatile memory, spin-based logic, and microwave signal generation. However, the accurate quantification and interpretation of these torques remains complicated by experimental sensitivity, the co-symmetry of the Oersted field and the effective field due to the field-like torque, and assumptions regarding the material layers from which the torques originate. The body of work set forth in …

A Longitudinal Study Of Achilles Tendon Adaptation In Ncaa Division I Female Gymnasts: Associations With Menstrual Status, Birth Control Use, Pain, Limb Dominance, And Training Exposure, Mattie Jane Hyde

Electronic Theses and Dissertations

This longitudinal study evaluated Achilles tendon (AT) thickness in 22 NCAA Division I (DI) female gymnasts across three consecutive seasons in relation to menstruation, birth control use, pain, limb dominance, training week, and year of collegiate competition. Weekly ultrasound and athlete survey data were analyzed using mixed-effects models for absolute AT thickness and change in thickness from baseline measurements. Associations were primarily characterized by interactions rather than uniform effects of individual predictors. A Pain × Limb Dominance × Week × Year interaction was associated with both thickness outcomes across season-specific and combined analyses, with relationship directions varying by limb, season …

Extreme Geomagnetic Storm Effects On Earth's Radiation Belts Observed By Calet On The International Space Station, Anthony W. Ficklin

LSU Doctoral Dissertations

This dissertation examines changes in Earth's energetic-particle environment using measurements from the Calorimetric Electron Telescope (CALET) on the International Space Station. Although CALET was designed primarily for high-energy cosmic-ray and gamma-ray observations, its count rates provide nearly continuous measurements of particles of ~1 MeV and above. The analysis uses the CHDX, CHDY, and IMC4X channels, which have approximate electron thresholds of $>\!1.5$, $\!>3.4$, and $\!>8.2$~MeV and proton thresholds of $>\!17$, $\!>37$, and $\!>52$~MeV, respectively. Because these measurements do not identify particle species, the observations are interpreted using their geographic and geomagnetic distributions, the relative …

Physical Design Automation For Next Generation Ics: Graph And Machine Learning Based Approaches, Dr. Kritanta Saha

Doctoral Theses

Integrated Circuit (IC) technology has progressed significantly over the last six decades, culminating in billions of transistors on a chip. The widely used 193 nm immersion lithography process exceeds modern feature sizes, leading to layout pattern distortions and electrical violations. Mitigation techniques such as Multiple Patterning and Optical Proximity Correction become ineffective below 45 nm, prompting the development of several Next-Generation Lithography (NGL) methods such as Extreme Ultraviolet Lithography (EUVL), Multiple Electron Beam Lithography (MEBL). MEBL employs thousands to millions of e-beams in parallel to overcome throughput limitations. A 2D layout is partitioned into vertical stripes by stitch-lines (SLs), each …

Digital Presence In Live Hybrid Performance, Luke Cargill

Dartmouth College Master’s Theses

This thesis examines how digital presence, the sense that a digital performer is socially and performatively "there," is designed and tested in live hybrid performance. Drawing on four practice-based projects (Vicarious, Voltage, Vicarious: Encore Edition, and SUPER BLOOM), the first phase identifies a recurring but empirically untested claim: that digital presence depends on interactivity and co-presence with live performers, though these factors were always entangled in practice.

The second phase tests this claim directly. A new mini-performance, featuring the first fully AI-driven digital character in this line of work, was produced for controlled comparison. Using a 3 (intro type: AI-driven, …

Developing Field And Spaceflight Microscopy, Nikki Johnston

Dissertations and Theses

Designing for spaceflight favors the reduction of unnecessary features and cost-cutting, whether thisbe computation, hardware, or procedure. Resources are spent toward fortification and mission success over convenience. Such design goals paired with the relatively smaller budgets of academia lead us to do as much as we can in-house and use open-source as much as we can without compromising mission success. We also believe that thoroughly testing technology in extreme environments on earth is necessary for the success of a flight instrument. We focus on microscopy for life detection. I have spent my time here learning methods of hand-building microscopes to …

Lightweight End-To-End Cryptographic Framework With Semantic Qos For Ar-Based Telesurgery, Pavan Kumar Satram

Masters Theses

This thesis presents the design, implementation, and evaluation of a lightweight end-to-end cryptographic framework integrated with a semantic quality-of-service classification system for augmented reality based telesurgery. Telesurgery can deliver expert surgical care to underserved populations, but adoption has been limited by unresolved cybersecurity, network performance, and resilience challenges. The core tension is that strong encryption adds latency that may exceed the clinical safety threshold, while unencrypted systems remain vulnerable to attacks that could endanger patients during live procedures.

The framework addresses this tension through a dual-edge security middlebox that performs per-flow encryption using semantically selected ciphers: AES-128-GCM for latency-critical haptic …

Electronic Structure Discretization And Compression Using Diagonal Basis Sets, Casey Lee Dowdle

Dartmouth College Ph.D Dissertations

Numerically solving the electronic structure problem is a fundamentally difficult problem due to the exponential growth in the dimension of the Hilbert space as the system size increases. In order to solve problems at a chemically relevant accuracy, both the choice of basis set and numerical method are important factors that are intrinsically connected.

In this thesis, we study the discretization and resulting compression of electronic Hamiltonians using diagonal basis sets. A diagonal basis set approximately diagonalizes the matrix and tensor representations of the one- and two-body potentials. This can reduce storage, simplify matrix-vector products, and lower the complexity of …

Behavior Of Magnetic Reconnection In The Relativistic Regime Under The Presence Of Shear Flows And Guide Field, Sarah Peery

Dartmouth College Ph.D Dissertations

Magnetic Reconnection is a ubiquitous phenomenon in plasma, where magnetic energy is released into plasma thermal and kinetic energy through the rearrangement of magnetic topology. In this study we derive fluid scaling models to predict the steady state and onset behavior of magnetic reconnection in the highly magnetized (relativistic) regime, in the presence of plasma shear flows and a (out-of-plane) guide field. We use 2.5D kinetic particle-in-cell simulations to motivate and validate these models. We find that, similar to the non-relativistic regime, shear flows parallel to the reconnecting magnetic field will delay reconnection onset and slow outflow jets. They can …

Synthesis, Utilization And Biological Evaluation Of Β-Hairpin Peptides As Inhibitors Of Immune Checkpoints, Sarah Naylon

Electronic Theses and Dissertations 2020 - Present

Peptide therapeutics have emerged as promising alternatives to monoclonal antibodies because of their smaller size, improved tissue penetration, and synthetic versatility. Yet their broader application is often limited by poor structural stability, rapid clearance, and reduced target residence times. This dissertation describes the design, synthesis, structural characterization, and biological evaluation of β-hairpin peptides as inhibitors of immune checkpoints and as peptide vaccine scaffolds while developing strategies to overcome these limitations. At first a series of antibody-derived β-hairpin peptides (mimics of complementary determining region heavy-chain 3: CDR-H3s) as covalent inhibitors of the PD-1/PD-L1 immune checkpoint were investigated. Electrophilic warheads were incorporated …

Long-Term Effects Of Harvesting Disturbance And Site Preparation On Soil Properties And Tree Growth In A Loblolly Pine (Pinus Taeda) Forest, Kyle M. Caccamesi

LSU Master's Theses

Productivity decline between rotations has long been a concern in intensively managed forest plantations. Research done over the last century has provided greater clarity on why this phenomenon occurs. The objective of this research was to observe long-term soil and tree growth characteristics that are likely to be influenced by operational harvesting activities. The experiment was conducted in Washington Parish, Louisiana on a site dominated by Ruston soil series, a well-drained, fine loamy, siliceous and thermic typic Paleudult. A randomized complete block design with 2 x 2 x 2 factorial treatments was used. The treatment factors were harvesting method, fertilization, …

Machine Learning Applications To Physical Processes, William Charles

Arts & Sciences Graduate Student Theses and Dissertations

This thesis demonstrates how machine learning techniques can solve computationally challenging problems across diverse areas of physics, from high-energy astrophysics to condensed matter systems, accelerating traditional computation. My first contribution addresses the computational expense of Monte Carlo calculations for radiative processes in relativistic plasmas. I develop a neural network sampling method that enables fast sampling from an arbitrary probability density, and demonstrate the method on inverse Compton scattering, achieving a speedup of up to an order of magnitude beyond standard methods. My second contribution addresses the structure and radiation of neutron star magnetospheres. I use physics-informed neural networks to model …

X-Ray Emission From V1674 Her (Nova Her 2021) And Characterization Of Cebr3 Detectors For Gamma-Ray Spectrometry, Tekeba Olbemo

Arts & Sciences Graduate Student Theses and Dissertations

Novae are thermonuclear explosions on the surface of the white dwarf in a close binary system. They are multi-wavelength transients emitting across the electromagnetic spectrum from radio to gamma-rays. This thesis primarily focuses on the X-ray emission from one particular nova, V1674 Her. V1674 Her (Nova Her 2021) is known for its ultra-fast decline time of ��2 ∼ 1 day. This under normal circumstances implies massive white dwarf potentially approaching the Chandrasekhar limit. We test this for V1674 Her by measuring its mass via X-ray spectroscopy method. The method calculates X-ray emission from physically motivated model of post-shock accretion column …