Physical Sciences and Mathematics Commons^™

La Vida: Towards A Motivated Goal Reasoning Agent, Ursula Addison

Dissertations, Theses, and Capstone Projects

An autonomous agent deployed to operate over extended horizons in uncertain environments will encounter situations for which it was not designed. A class of these situations involves an invalidation of agent goals and limited guidance in establishing a new set of goals to pursue. An agent will benefit from some mechanism that will allow it to pursue new goals under these circumstances such that the goals are broadly useful in its environment and take advantage of its existing skills while aligning with societal norms. We propose augmenting a goal reasoning agent, i.e., an agent that can deliberate on and self-select …

Categorical Chain Conditions For Étale Groupoid Algebras, Sunil Philip

Dissertations, Theses, and Capstone Projects

Let R be a unital commutative ring and G an ample groupoid. Using the topology of the groupoid G, Steinberg defined an étale groupoid algebra RG. These étale groupoid algebras generalize various algebras, including group algebras, commutative algebras over a field generated by idempotents, traditional groupoid algebras, Leavitt path algebras, higher-rank graph algebras, and inverse semigroup algebras. Steinberg later characterized the classical chain conditions for étale groupoid algebras. In this work, we characterize categorically noetherian and artinian, locally noetherian and artinian, and semisimple étale groupoid algebras, thereby generalizing existing results for Leavitt path algebras and introducing new results for inverse …

Twisted Alexander Polynomials And Ptolemy Varieties Of Knots And Surface Bundles, Michael R. Marinelli

Dissertations, Theses, and Capstone Projects

The first focus of this dissertation is to compute Ptolemy varieties for triangulations of two infinite families of manifolds. Given an ideal triangulation of a cusped manifold, one can compute the Ptolemy variety and using it, obtain parabolic representations of the fundamental group. We compute certain obstruction classes for these manifolds, which are necessary to obtain the discrete faithful representation. This leads to our second focus of the dissertation, the twisted Alexander polynomial. The twisted Alexander polynomial (TAP) is a variation of the classical Alexander polynomial twisted by a representation of the fundamental group into a linear group. It was …

Shear Viscosity Of Quasi One-Dimensional Bec Tubes And Entanglement Negativity Conditions, Camilla Polvara

Dissertations, Theses, and Capstone Projects

Shear Viscosity of Quasi One-dimensional BEC Tubes

We consider layered Bose-Einstein condensates interacting via contact intra-condensate interacions and dipolar inter-condensate potentials, both of which dominate intercondensate tunneling (which we neglect for simplicity). For this system, we compute the normal modes, we study its localization properties by numerically computing the inverse participation ratio, and we compute the inter-tube shear viscosity.

Entanglement Negativity Conditions

This project explores bounds on entanglement negativity using operator inequalities, building on the results of [1]. We are looking for a way to quantify entanglement, as an alternative to calculating the full negativity, which would otherwise require the …

Interplay Of Magnetic Impurities And Superconductivity In Topological Materials, Didier Ndengeyintwali

Dissertations, Theses, and Capstone Projects

The interplay of superconductivity and magnetism has been a long-standing topic of interest since the discovery of superconductivity. In recent years it has been shown that topological superconductivity, which has promising applications such as in topological quantum computing, could result from such interplay. Motivated by the later results I study the effect of magnetic impurities in superconducting doped topological insulators, such as Iron based topological superconductors. I show that topological character of parent materials could lead to modifications in the structure of magnetic impurity induced in-gap states. Moreover, the superconductivity induced interaction between magnetic impurities in doped topological insulator would …

Geology Of Sinai Tholus, Thaumasia Plateau, Mars, Haley Mosher

Theses and Dissertations

A new geologic map of the Sinai Tholus region on the Thaumasia plateau, Mars reveals the structural, magmatic, and stratigraphic complexity that can be found in the Tharsis region on Mars, and may help answer key questions about the origin of the subvolcanic basement, evolution of the regional stress field, development of Valles Marineris, and magmatic history of the region. Sinai Tholus is a topographic high in a relatively flat, lava flow covered part of Thaumasia Plateau, just south of the central part of Valles Marineris. Here, five stratigraphic units and one generalized impact unit have been mapped at a …

The Characterization And Electrochemistry Of Natural Uranium Dioxide Under Long-Term Disposal Conditions, Martin D. M. Badley

Electronic Thesis and Dissertation Repository

This thesis describes the studies performed on a number of natural uranium dioxide (UO₂) specimens to determine a range of reactivities. This work will support the safety case for the long-term disposal of spent nuclear fuel in Canada. Under relevant long-term disposal conditions, water radiolysis could produce oxidizing conditions at the surface of the fuel, potentially leading to fuel corrosion and the release of radionuclides into the groundwater. The rate of such a process would be determined by the radiation dose rate from the fuel and the reactivity of the fuel, which will be determined by its composition, …

Open Quantum Systems In High Energy Physics, Bharath Sambasivam

Dissertations - ALL

Open quantum systems (OQS) are ubiquitous in various fields of physics, such as high energy physics, cosmology, atomic and molecular physics, and quantum optics. In some cases, there is a natural separation between the system and the environment, like the presence of a horizon in inflationary cosmology. In other cases, like field theories coupled to thermal baths or at finite chemical potential, it is not practical to simulate the large number of degrees of freedom making up the bath. The system of interest can be described by an effective theory upon integrating out the environment degrees of freedom. In certain …

Investigating The Cellular Localization, Trafficking, And Biological Function Of Ghrelin O-Acyltransferase, Sadie Xiao Hua Novak

Dissertations - ALL

Ghrelin O-acyltransferase (GOAT) catalyzes the acylation and activation of ghrelin, a peptide hormone involved in a range of physiological pathways and therapeutic target for metabolism-linked diseases such as obesity and diabetes. GOAT was determined to be localized in the membrane of the endoplasmic reticulum (ER) in early cell-based studies, but recent patient studies detected this integral membrane enzyme in blood plasma and urine. These findings challenge the current understanding of GOAT’s cellular localization, and it may provide a potential mechanism for ghrelin re-acylation by plasma membrane-resident GOAT. The work described in this dissertation aimed to define the intracellular trafficking mechanism …

Studies Towards Improved Gravitational Wave Detector Thermodynamics, Daniel Vander-Hyde

Dissertations - ALL

Since the first gravitational wave detection, the Laser Interferometric Gravitational Wave Observatories (LIGO) combined with an expanding and co-observing global gravitational wave network (i.e. Virgo, KAGRA) has worked to increase a novel and growing astronomical data catalog of gravitational wave detections. With each additional observing run, rates of detection continue to increase with iterative upgrades to detector technology. Discussed within this thesis are considerations pertinent to the improvement of Dual Recycled Fabry-Perot Michelson interferometer (DRFPMI) thermodynamics proposed during LIGO's third observing run (O3) for present and future detectors. The first chapter reviews fundamental material relevant to gravitational waves and how …

Competition Effects In An Intraguild Predation Model, Nicholas A. Eekhof

Electronic Thesis and Dissertation Repository

In the biological world, many interactions exist between various species. These interactions generally consist of predator-prey relationships, competition between species and beneficial relationships. One observed phenomenon, termed the fear effect, occurs when one species reacts to an increased risk of predation by another species. The fear response causes the affected species to reproduce and forage for food less. In some cases, the fear response can be beneficial, while in other times it can be harmful. In this thesis, we consider a four compartment food-chain model in which there exists a top-level predator, a mesopredator and two types of prey who …

Host-Pathogen Co-Evolution With Various Transmission Modes Of Infection And Density-Dependent Dynamics, Bita Ghodsi

Electronic Thesis and Dissertation Repository

Pathogens can be transmitted both vertically (from the parent to the offspring) and horizontally. Here, I model the co-evolution of pathogens and their hosts allowing for vertical and horizontal transmission and density-dependent host population growth. My analysis uses evolutionary game theory. I use computational methods to find that increasing vertical transmission does not always result in more benign disease outcomes. Instead, it can lead to higher pathogen-induced mortality. Furthermore, more benign outcomes evolve more readily when horizontal transmission is more profitable for the pathogen, and overall virulence increases as horizontal transmission becomes more profitable. The results also indicate that vertical …

Understanding Protein Deep Learning Models Through Explainability, Zahra Fazel

Electronic Thesis and Dissertation Repository

This thesis investigates the application of Explainable Artificial Intelligence (XAI) techniques to deep learning models in the field of protein analysis, specifically targeting protein language models and protein interaction site prediction models. Despite the increasing adoption of these sophisticated deep learning models in bioinformatics, their intrinsic complexity often results in a black-box nature, obscuring the understanding of their decision-making processes.

This research represents a thorough effort to integrate explanation methods within this context. We analyze the resulting interpretations using biological-specific statistical tests to enhance the transparency and interpretability of the models. This work evaluates the efficacy of current XAI methods …

Osculating Curves, Sepideh Bahrami

Electronic Thesis and Dissertation Repository

Consider a complex analytic curve $X$ in $\mathbb{C}^2$, along with a specific point $p \in X$. The primary concern arises in approximating geometrically the curve $X$ precisely at the point $p$. Analogously, in introductory calculus, students learn to compute the tangent line to the graph of a function $y=f(x)$ at a given point $p=(x_*,f(x_*))$ by utilizing the derivative of $f$ at $x_*$.

For analytical convenience, we assume a local representation of the curve $X$ using a power series expansion. This representation centers the point $p$ at the origin $(0,0) \in \mathbb{C}^2$. Thus, our mathematical input becomes a Taylor series:

\[ …

A Coarse-Grained Molecular Dynamics Study Of Gas Hydrate Formation And Dissociation, Meisam Adibifard

LSU Doctoral Dissertations

The study of gas hydrates has increased significantly over the last two decades because of their potential application in energy storage, production and transportation, water desalination, refrigeration, gas separation, etc. There is a significant interest in commercially developing natural gas hydrates because the energy content of methane hydrate reservoirs (MHRs) is at least twice that of all conventional fossil fuels combined. Additionally, due to the higher storage capacity of hydrates, it is proposed to sequester CO₂ in the form of CO₂ hydrate, thereby reducing the amount of greenhouse gases. Hence, hydrates offer a dual solution to two of …

Predictive Filtering-Based Image Inpainting, Xiaoguang Li

Theses and Dissertations

Image inpainting is an important challenge in the computer vision field. The primary goal of image inpainting is to fill in the missing parts of an image. This technique has many real-life uses including fixing old photographs and restoring ancient artworks, e.g., the degraded Dunhuang frescoes. Moreover, image inpainting is also helpful in image editing. It has the capability to eliminate unwanted objects from images while maintaining a natural and realistic appearance, e.g., removing watermarks and subtitles. Disregarding the fact that image inpainting expects the restored result to be identical to the original clean one, existing deep generative inpainting methods …

Mild Hydrothermal Crystal Growth Strategies For Complex Inorganic Metal Fluorides, Navindra Keerthisinghe

Theses and Dissertations

Inorganic metal fluorides have been investigated for their interesting magnetic and optical properties, their electrochemical behavior, and their ionic conductivity. Fluoride materials can accommodate metals in very low oxidation states, which can be advantageous for designing new magnetic materials. Specifically, mixed metal fluorides incorporating transition metal cations often exhibit interesting magnetic behavior, such as frustrated magnetism. However, many challenges are encountered during the synthesis of such fluoride materials, including the inability to perform reactions under ambient conditions and the involvement of toxic gases for fluorination during solid-state reactions. Therefore, solution growth techniques such as mild hydrothermal synthesis are currently utilized …

Synergetic And Orthogonal Switching In Dual Photochromic Metal-Organic Frameworks, Gina Rene Wilson

Theses and Dissertations

Cooperative behavior and orthogonal responses of two classes of coordinatively integrated photochromic molecules towards distinct external stimuli were demonstrated on the first example of a photo-thermo-responsive hierarchical platform. Synergetic and orthogonal responses to temperature and excitation wavelength are achieved by confining the stimuli-responsive moieties within a metal-organic framework (MOF), leading to the preparation of a novel photo-thermo-responsive spiropyran-diarylethene based material. Synergistic behavior of two photoswitches enables the study of stimuli-responsive resonance energy transfer as well as control of the photoinduced charge transfer processes, milestones required to advance optoelectronics development. Spectroscopic studies in combination with theoretical modeling revealed a nonlinear effect …

Impact Of Energy Allocation On Fish's Age And Weight At Maturation By Mathematical Models, Siyi Zhang

Electronic Thesis and Dissertation Repository

The age and weight at maturation are crucial traits in an organism’s life cycle, influencing its growth, survival, and reproduction. We propose a biphasic energy allocation model, distinguishing pre-maturity and post-maturity, to study the mechanisms of maturation and estimate the age and weight at maturation. This model is parameterized for female lake whitefish (Coregonus clupeaformis). We compare different functions involved in the model, estimate parameters, and do sensitivity analysis. Our results indicate that (i) weight at maturation is positively related to the fraction of energy allocated to growth which, by data fitting, is almost a constant; (ii) age …

Macro–Micro-Coupled Simulations Of Bead–Spring Breaking-Reforming Networks, Andrei Medved

Theses and Dissertations

In this work we investigate the dynamic behavior of bead-spring polymer solutions in viscoelastic fluids, which are essential in industries like materials science, biotechnology, and pharmaceuticals. The study leverages GPU-accelerated simulations and detailed modeling of polymer chain dynamics at the mesoscale, which enables efficient analysis of intricate fluid behaviors and the microscale dynamics of polymer chains. Additionally, the research examines the breaking-reforming dynamics of polymer chains, crucial for understanding phenomena such as shear thinning and thickening. The findings have broad applications, from improving inkjet printing and 3D printing technologies to developing new drug delivery systems and biocompatible materials. This work …

2023 Analysis Of Microplastics In Bed Sediments Of The Puget Sound In The Salish Sea, Mia Robbins

Environmental Science Undergraduate Theses

Pollution of bays and estuaries by microplastics is an increasingly pressing concern, especially in bodies of water surrounded by densely populated areas. Microplastics have been found in waters virtually everywhere. Microplastics are known to be vectors for harmful chemicals and can impact digestion and other physiological processes in organisms. Quantifying the number of microplastics in the Puget Sound can give a clearer picture of the local scope of this issue. With this work, we monitored the levels of microplastics in sediments at 50 sites in the Puget Sound and related them to 2021. Sediments were disaggregated and density separated to …

2023 Analysis Of Harmful Algae In Bed Sediments Of The Puget Sound In The Salish Sea, Peyton Scheschy

Environmental Science Undergraduate Theses

Alexandrium catenella is a toxic dinoflagellate that has two life stages, a dormant cyst form within bed sediment, and a vegetative form that swims freely in the water column. Both produce a saxitoxin that can bioaccumulate within shellfish and when ingested by mammals, could potentially lead to paralytic shellfish poisoning (PSP). This project looked at the distribution of cysts of A. catenella in the Salish Sea to inform shellfish harvesters of the potential for harmful algal blooms in their region. In order to analyze for cysts, sediment was collected at 50 stations throughout the Salish Sea. These samples were processed …

Modeling, Analysis, Approximation, And Application Of Viscoelastic Structures And Anomalous Transport, Yiqun Li

Theses and Dissertations

(Variable-order) fractional partial differential equations are emerging as a competitive means to integer-order PDEs in characterizing the memory and hereditary properties of physical processes, e.g., anomalously diffusive transport, viscoelastic mechanics and financial mathematics, and thus have attracted widespread attention. In particular, optimal control problems governed by fractional partial differential equations are attracting increasing attentions since they are shown to provide competitive descriptions of challenging physical phenomena. Nevertheless, variable-order fractional models exhibit salient features compared with their constant-order analogues and introduce mathematical difficulties that are not typical encountered in the context of integer-order and constant-order fractional partial differential equations.

This dissertation …

Deconvolving Provenance Signatures Of Pliocene-Pleistocene Coastal Loess Deposits Along The Atlantic Margin Of Argentina, Will Robert Quanrud

Theses and Dissertations

Dust derived from southern South America provides critical nutrients for autotropic marine biota in the South Atlantic Ocean, such that fluxes of wind-blown sediment may ultimately affect the concentration of atmospheric CO2. Expansive sand, silt, and loess deposits are exposed in Central Argentina, recording millions of years of eolian processes; however, the provenance and transport pathways of this dust remains unclear. Coastal loess deposits ranging in age from Pliocene to upper Pleistocene are present along the Atlantic margin of Argentina and provide information on sediment transport pathways for the last 4 million years. Nine samples of loess were collected and …

Advances In Chalcogenide Crystal Growth, Anna Berseneva

Theses and Dissertations

Chalcogenides are the cornerstone of the semiconductor and thermoelectric industries and are up-and-coming materials for superconductors, catalysis, and battery applications. Challenges in the synthesis of those materials emerge from the chalcogen’s volatility and the tendencies of chalcogenide to react with even trace quantities of oxygen. Nonetheless, many techniques have been applied to the growth of chalcogenide single crystals, which are convenient for structure determinations and intrinsic property measurements. This dissertation will detail synthetic strategies applied to the crystal growth of novel chalcogenide materials via molten flux preparation (Chapters 2, 4, and 5), hydrothermal synthesis (Chapter 1 and 3), and single-crystal-to-single …

Bayesian Methods In Analyzing The Diagnostic Accuracy\\ For Ordinal Ratings, Yun Yang

Theses and Dissertations

This dissertation focuses on ordinal classification ratings, which are commonly used in medical practice to assess the severity of a disease or condition. For example, a group of radiologists rate a set of mammograms and assign BI-RADS (Breast Imaging Reporting Data System) score for each mammogram. A Bayesian probit hierarchical model is first proposed to analyze this type of data. It links the ordinal ratings with both rater diagnostic skills and patient latent disease severity. Each rater diagnostic skills are quantified with two parameters, diagnostic bias and diagnostic magnifier. Patient latent disease severity is assumed to follow a different normal …

Object Classification, Detection And Tracking In Challenging Underwater Environment, Md Modasshir

Theses and Dissertations

The main contributions of this thesis is the applicability and architectural designs of deep learning algorithms in underwater imagery. In recent times, deep learning techniques for object classification and detection have achieved exceptional levels of accuracy that surpass human capabilities. However, the effectiveness of these techniques in underwater environments has not been thoroughly researched. This thesis delves into various research areas related to underwater environments, such as object classification, detection, semantic segmentation, pose regression, and semi-supervised retraining of detection models.

The first part of the thesis studies image classification and detection. Image classification is a fundamental process that involves assigning …

Generalizations Of The Graham-Pollak Tree Theorem, Gabrielle Anne Tauscheck

Theses and Dissertations

Graham and Pollak showed in 1971 that the determinant of a tree’s distance matrix depends only on its number of vertices, and, in particular, it is always nonzero. This dissertation will generalize their result via two different directions: Steiner distance k-matrices and distance critical graphs. The Steiner distance of a collection of k vertices in a graph is the fewest number of edges in any connected subgraph containing those vertices; for k = 2, this reduces to the ordinary definition of graphical distance. Here, we show that the hyperdeterminant of the Steiner distance k-matrix is always zero if …

Representation Dimensions Of Algebraic Tori And Symmetric Ranks Of G-Lattices, Jason Bailey Heath

Theses and Dissertations

Algebraic tori over a field k are special examples of affine group schemes over k, such as the multiplicative group of the field or the unit circle. Any algebraic torus can be embedded into the group of invertible n x n matrices with entries in k for some n, and the smallest such n is called the representation dimension of that torus. Representation dimensions of algebraic tori can be studied via symmetric ranks of G-lattices. A G-lattice L is a group isomorphic to the additive group Zⁿ for some n, along with an action …

Metal-Organic Frameworks For Global Environmental Challenges, Kyoungchul Park

Theses and Dissertations

Over the past few decades, there has been a demand for improving nuclear waste administration due to a significant increase in the utilization of nuclear energy. The driving force for proper nuclear waste disposal is evident when considering past nuclear catastrophes—such as Chernobyl and Fukushima—where radionuclide contamination of large bodies of water sparked public concern. In order to manage such radioactive species, the emerging areas of radionuclide sequestration, storage, separation, and sensing must be addressed in the upcoming years. This dissertation presents a potential candidate for addressing these challenges, called metal-organic frameworks (MOFs). Due to their porosity, high surface area, …