Digital Commons Network^™

Evolution Semigroups For Well-Posed, Non-Autonomous Evolution Families, Austin Keith Scirratt

LSU Doctoral Dissertations

The goal of this dissertation is to expand Berhard Koopman's operator theoretic global linearization approach to the study of nonautonomous flows. Given a system with states x in a set \Omega (the state space), a map t\to \gamma(t,s,x) (t\geq s \geq 0) is called a global flow if it describes the time evolution of a system with the initial state x \in \Omega at time t \geq s \geq 0. Koopman's approach to the study of flows is to look at the dynamics of the observables of the states instead of studying the dynamics of the states directly. To do …

Black Girl Magic: How Black Women Administrators Navigate The Intersection Of Race And Gender In Workspace Silos At Predominantly White Institutions, Allison Michelle Smith

LSU Doctoral Dissertations

In choosing to look at the impact of white racially homogeneous work environments, if any, in relation to Black women higher education administrators, this research was grounded in Patricia Hill Collins’ Black Feminist Thought. Utilizing Black Feminist Thought, rooted in intersectionality, provided a sturdy foundation for one interested in conducting research specific to Black women, whether the discourse is race, gender, and/or any other intersecting identities. Black Feminist Thought conveys the message that Black women have similar yet different experiences from White women and similar yet different experiences from Black men, while simultaneously having shared yet different experiences than other …

Method Of The Riemann-Hilbert Problem For The Solution Of The Helmholtz Equation In A Semi-Infinite Strip, Ashar Ghulam

LSU Doctoral Dissertations

In this dissertation, a new method is developed to study BVPs of the modified Helmholtz and Helmholtz equations in a semi-infinite strip subject to the Poincare type, impedance and higher order boundary conditions. The main machinery used here is the theory of Riemann Hilbert problems, the residue theory of complex variables and the theory of integral transforms. A special kind of interconnected Laplace transforms are introduced whose parameters are related through branch of a multi-valued function. In the chapter 1 a brief review of the unified transform method used to solve BVPs of linear and non-linear integrable PDEs in convex …

Developing A Mathematically Informed Approach To Musical Narrative Through The Analysis Of Three Twentieth-Century Monophonic Woodwind Works, Wesley James Bradford

LSU Doctoral Dissertations

This project applies mathematically informed narrative to monophonic music in the twentieth century, with a focus on three works for solo woodwinds: Debussy’s Syrinx (flute), Stravinsky’s Three Pieces for Clarinet, and Britten’s “Bacchus” from Six Metamorphoses after Ovid, Op. 49 (oboe). This music poses difficulties for traditional analytical methods due to a lack of explicit harmonies and unusual pitch language that is neither functionally tonal nor serially atonal. Additionally, these pieces present a variety of challenges due to differences in length, number of movements, and presence or absence of programmatic elements. Therefore, nontraditional methods could be beneficial for understanding these …

A Conditioned Gaussian-Poisson Model For Default Phenomena, Tyler Brannan

LSU Doctoral Dissertations

We introduce a new model to study the behavior of a portfolio of defaultable assets. We refer to this model as the Gaussian-Poisson model. It builds upon one-factor Gaussian copula models and Poisson models (specifically Cox processes). Our model utilizes a random variable Y along with probability measures ℙ^• and ℙ^†. The measures ℙ^• and ℙ^† will act as market pricing measures and are obtained via conditioning. The random variable Y will act as a default descriptor.

We provide the distribution of Y under both ℙ^• and ℙ^†. We use a conditional …

Direct Measurements Of Nuclear Reactions In Hot Stellar Environments, Kevin Thomas Macon

LSU Doctoral Dissertations

Understanding the origins of intermediate mass nuclei requires accurate knowledge of nuclear reaction rates. This thesis addresses two projects targeting measurements of nuclear cross sections relevant in hot astrophysical environments. Direct measurements of neutron capture on ⁶⁷Zn and ⁶⁸Zn were performed using the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center (LANSCE). A new ⁶⁸Zn(n,&gamma) cross section in the neutron energy range from 150 eV to 850 keV and Maxwellian-Averaged Cross Sections from 20 keV-100 keV are presented along with the details of the analysis. These reaction rates are important for …

Vegetation Influences Microbial Community Structure And Methane Emissions In Southeastern Louisiana Wetlands, Anthony Jason Rietl

LSU Doctoral Dissertations

Methane has a warming potential 28 times that of carbon dioxide and has been increasing in the Earth’s atmosphere since 1750. An understanding of the dynamics of methane emissions from natural sources is becoming increasingly important as we may need to mitigate emissions from these sources in the future to help reduce the effects of climate change. Wetlands are the single largest natural source of methane; however, little attention has been given to how plant species, biota, and interactions between above and belowground communities and microbial communities may affect methane emissions. First, microbial community structure and function was assessed for …

Peptidomimetic Polymers: Advances In Monomer Design And Polymerization Methods, Brandon Andrew Chan

LSU Doctoral Dissertations

This work is focused on the design, synthesis and characterization of polypeptide and polypeptoid polymers. The former are composed of amino acid repeat units and possess intramolecular hydrogen bonding interactions allowing for the self-assembly into well-defined secondary structures (e.g. α-helix). Polypeptoids are based on N-alkyl substituted glycine and lack intramolecular hydrogen bonding interactions, resulting in enhanced proteolytic stability and thermal processability. Physicochemical properties of polypeptoids are strongly dependent on the side chain structures, allow for control of the solubility, crystallinity, and conformation of the polymers. Well-defined polypeptides and polypeptoids are synthesized by the ring-opening polymerization (ROP) of their corresponding N-carboxyanhydride …

Contemporary Organic Transformations Enabled By Novel Cationic Processes, Caitlan Elizabeth Ayala

LSU Doctoral Dissertations

This dissertation focuses on the development of synthetic methodologies in organic synthesis in two different areas. Chapter 1 discusses the more recent examples of transforming alcohols to their corresponding alkyl chlorides. The first area of our group’s research interest is the development of a mild chlorination method from unactivated alcohols, detailed in Chapter 2. Chapter 3 provides an insight into the history of oxyallyl cations, the basis of the second methodology development project in our laboratory. This chapter focuses on the traditional reactions that utilize these reactive intermediates, and it also showcases the concept of direct nucleophilic addition and the …

Circumstellar Dust Shells: Clues To The Evolution Of R Coronae Borealis Stars, Edward Joseph Montiel

LSU Doctoral Dissertations

The existence of extended, cold dust envelopes surrounding R Coronae Borealis (RCB) stars has been known about for over 30 years. RCB stars are an exotic group of extremely hydrogen-deficient, carbon-rich supergiants that are known for their spectacular declines in brightness (up to 8 mags) at irregular intervals. There are three possible origins of these envelopes: (1) they are fossil planetary nebulae (PNe), indicating that RCB stars formed via a final Helium-shell flash; (2) they are the remnant material from the merger of a CO and a He white dwarf binary, (3) they have been constructed from dust ejection events …

Intracontinental Neotectonics: Case Studies From The Tian Shan Orogen And Kuqa Fold-Thrust Belt, Cindy M. Colón

LSU Doctoral Dissertations

This dissertation focuses on the kinematic properties of intracontinental deformation during short geologic time scales. Using three case studies this work characterizes active deformation at varying spatial scales within the continental interior of Eurasia. The far-field effect of the Cenozoic Indo-Asia collision is the driving force controlling deformation within the Eurasian continental interior. Active deformation across the intracontinental Tian Shan range challenges the plate tectonic model that proposes crustal deformation is concentrated along plate boundaries. This work further constrains the active kinematics of intracontinental motion that is necessary to understand the dynamics of the Eurasian intracontinental system. The two standing …

Conjunctive Management Of Water Resources Under Climate Change Projection Uncertainty, Amir Mani

LSU Doctoral Dissertations

Goal of this study is to investigate the impacts of climate change projection uncertainty on conjunctive use of water resources. To pursue this goal first, a conjunctive-use model is developed for management of groundwater and surface water resources via mixed integer linear fractional programming (MILFP). The conjunctive management model maximizes the ratio of groundwater usage to reservoir water usage. A conditional head constraint is imposed to maintain groundwater sustainability. A transformation approach is introduced to transform the conditional head constraint into a set of mixed integer linear constraints in terms of groundwater head. A supply network is proposed to apply …

Hybrid Inorganic Core- Conjugated Polymer Shell Nanoparticles Prepared By Surface-Initiated Polymerization, Sourav Chatterjee

LSU Doctoral Dissertations

Hybrid core-shell nanoparticles have attracted attention due to their unique characteristics which combine properties of the inorganic core and organic shell in a way that generates new properties which do not exist for the two individual parts. This makes them promising candidates for the design of stimuli-responsive materials, chemo- and biosensors, and various biomedical applications. In this dissertation research, we designed and prepared a series of hybrid environmentally responsive nanoparticles where fluorescent block copolymers, including various combinations of polythiophene (PT), poly(p-phenylene) (PPP), poly(3-hexylthiophene) (P3HT) and polyallene (PA), were grafted on the surface of inorganic nanoparticles using surface-confined Kumada catalyst-transfer polymerization. …

Coastal Ecosystem Resiliency After Major Disturbances, Giovanna Mcclenachan

LSU Doctoral Dissertations

Disturbances are a common occurrence in coastal ecosystems and can provide opportunity for adaptation and renewal in healthy systems; hurricanes bring mineral accretion to a marsh, floods provide a pulse of freshwater and nutrients to estuaries, and fires increase species diversity and abundance in forests. Humans, however, have depleted the resiliency of many coastal systems via top down and bottom up mechanisms, leaving these ecosystems more vulnerable to both natural and anthropogenic disturbances. Louisiana’s wetlands have been modified for centuries via canals, levees, agricultural impoundments, etc., leading to a decreased resiliency to land loss. The Deepwater Horizon (DWH) oil spill …

Interactions Between Local Magnetic Moments And Itinerant Charge Carriers In Fe-Based Systems, Yan Wu

LSU Doctoral Dissertations

The interactions between magnetic moments and electrons are essential in creating many of the unique properties of magnetic systems. In this thesis, I focused on two Fe-based systems employing multiple experimental techniques to investigate the coupling between localized magnetic moments and conducting charge carriers in two systems with tendencies to order into itinerant magnetic phases.\\ With systematic investigations of Fe$_{1-y}$Co$_y$Si, we discovered a field depended non-Fermi-Liquid (non-FL) behavior near its insulator-metal-transition (IMT) that appears to share the same mechanism as previously discovered in Mn doped FeSi - the underscreened Kondo effect.\\ A similar interaction of the charge carrier moments screening …

The Influence Of Enrollment In Career And Technical Education Courses On The Achievement Of High School Special Education Students, Melinda Simoneaux Partin

LSU Doctoral Dissertations

This dissertation joins a conversation in the special education arena about the academic and vocational agenda for special education high school students. It explores the influence of enrollment in Career Technical Education (CTE) courses on the achievement of high school special education (SPED) students. The purpose of this study was to compare the achievement of special education (SPED) students enrolled in Career Technical Education (CTE) courses with special education (SPED) students who were not enrolled in Career Technical Education (CTE) courses. The study was designed to determine whether or not SPED students enrolled in CTE improved on the academic scores …

Analysis Of Disruptions In The Gulf Of Mexico Oil And Gas Industry Supply Chain And Related Economic Impacts, Negar Dahitaleghani

LSU Doctoral Dissertations

Catastrophic events are human and economic tragedies in collaboration. Oil spills have enormous impacts on the local economy of the area and for the local labor markets. The Deepwater Horizon oil spill was caused by an explosion on semisubmersible drilling rig (Macondo) on April 20, 2010. Another regional disaster, Hurricane Katrina as it ripped over the core of the Gulf of Mexico producing zone, one of the most important oil and gas production region. With Geological complexities, continued of drilling and production in GoM increases the risk of having leak/spill. Therefore, the Econometrics methods, and Modeling to forecast impacts of …

Design And Analysis Of Geothermal Wellbore Energy Conversion System Working On Zero Mass Withdrawal Principle, Ildar Akhmadullin

LSU Doctoral Dissertations

This project is sponsored by the Department of Energy of the United States and dedicated to development of electricity production from the low-enthalpy geothermal reservoirs. The prime interest are reservoirs that are characterized by low temperature of heat source located in deep saline aquifers with high permeable rock. Usually energy production from these resources are not economical by using a conventional binary power plant approach. The presented PhD work is a study of a new system that utilizes a single-well technology and working on supercritical power cycle (PC). The wellbore energy conversion system is operating with Zero Mass Withdrawal (ZMW) …

Structure And Dynamics Of Layered Transition Metal Compounds Driven By Broken Symmetry, Chen Chen

LSU Doctoral Dissertations

Correlated Electron Systems have attracted attention because of their complex phase diagrams that often contain several exotic phases that cannot be understood at all with traditional ideas. This is driven by the competition between many low-lying states, competing to be the ground state. That means by tuning parameters like temperature, pressure, magnetic _x000C_field, or doping concentration, one phase would be suppressed and another emerges. These phases are in such a delicate balance that they compete and interact with each other, and experimentally we can always find a way to alter this balance. In this work, two systems have been investigated: …

Dynamics Of Land Building And Ecological Succession In A Prograding Deltaic Floodplain, Wax Lake Delta, La, Usa, Azure Elizabeth Bevington

LSU Doctoral Dissertations

Deltas are globally important locations of diverse ecosystems, human settlement and economic activity that are threatened by reduced sediment delivery, accelerated sea level rise, and subsidence. In this dissertation I investigated a number of aspects of the ecosystem development over time within an actively prograding river dominated delta along the northern Gulf of Mexico coast. I outlined a conceptual model of deltaic floodplain wetland establishment and succession focused on the vegetated deltaic floodplain ecosystem, which includes subtidal, intertidal and supratidal zones. This was used to guide the experimental design and statistically driven hypothesis testing in order to ascertain the validity …

Thiol-Acrylate Polymerization Kinetics And Applications In Microfluidics, Michael Perrin Tullier

LSU Doctoral Dissertations

The reaction kinetics and some applications in the field of microfluidics for thiol-acrylate Michael addition polymerizations using multifunctional monomers have been researched and are presented here. The polymerization rate constants for base-catalyzed systems were found to increase with increasing thiol and acrylate functionality, which was attributed to the intramolecular interactions between functional groups. The nucleophile-initiated thiol-acrylate Michael addition polymerization kinetics were monitored via FTIR, and it was determined that the increase in the rate of reaction in these multifunctional systems was significantly less dramatic than the increase observed in monofunctional systems. While no radical polymerization was observed during most typical …

An Investigation Of Environmentally Persistent Free Radical (Epfr) Formation In Contaminated Soils Using Surrogate-Based Model Systems, Ugwumsinachi Godwin Nwosu

LSU Doctoral Dissertations

Environmentally persistent free radicals (EPFRs) have recently attracted attention due to their properties that detrimental to the health of living organisms. Earlier studies devoted to the formation of combustion generated particulate matter (PM) showed that EPFRs formed as a result of the association of aromatic chlorinated hydrocarbons with transition metal centers. Based on our previous studies, the amounts of EPFRs formed at Superfund soil sites contaminated with pentachlorophenol (PCP) are ~30 times higher compared to those formed at the neighboring uncontaminated soil sites, showing that EPFR formation is not confined to combustion generated particle. In order to design viable remediation …

Production Of Fermentable Sugars From Energy Cane Bagasse, Saeed Oladi

LSU Doctoral Dissertations

Lignocellulosic biomass contains cellulose and hemicellulose which are composed of hexose and pentose sugars. These sugars can be used in the sustainable production of fuels and chemicals. However, the recalcitrant nature of lignocellulosic biomass makes this conversion a challenging process. An effective pretreatment can remove lignin, solubilize the hemicellulose, decrease cellulose crystallinity, and prepare the biomass for enzymatic hydrolysis and conversion into green renewable chemicals. The research study presented in this dissertation addressed some of the challenges associated with the conversion of lignocellulosic biomass into green fuels and chemicals. This study was divided into three main goals. The first goal …

Immune Gene Variation And Susceptibility To Upper Respiratory Tract Disease In Gopher Tortoises, Jean Pierre Elbers

LSU Doctoral Dissertations

The immune system defends the host from bacteria, fungi, parasites, and viruses. The immune system is partially under genetic control through immune response genes, such as those of the major histocompatibility complex (MHC) whose nucleotide variation influences the host’s ability to recognize foreign pathogens and can influence disease susceptibility. Populations of threatened species generally possess low levels of genetic variation, and genetically depauperate hosts may be at greater risk of infectious disease contributing to extirpations because they also possess low immunogenetic variation. My dissertation examines the relationship between immunogenetic variation and disease susceptibility and the factors that influence innate immune …

Evaluation Of Ammonia Volatilization And Zinc Nutrition Of Experimental Zinc Sulfate Coated Urea Fertilizers In A Drill-Seeded Delayed Flood Rice Production System, Nutifafa Adotey

LSU Doctoral Dissertations

Approaches in controlling nitrogen (N) loss from preflood fertilizer applications in delayed flood rice (Oryza stiva) production in the mid-southern U.S.A. typically involves treating urea with urease inhibitors like N-(n-butyl) thiophosphoric triamide (NBPT). Limited research exists on managing N utilizing the combined effects of treating urea with a urease inhibitor and subsequently adding a physical zinc (Zn) sulfate coating. Zinc deficiency is also a major soil fertility constraint in flooded rice production. The objectives of this study were to: (i) determine the ammonia volatilization potential of experimental zinc sulfate coated urea (ZSCU) fertilizers on four rice soils in a controlled …

Towards Theory And Applications Of Generalized Categories To Areas Of Type Theory And Categorical Logic, Lucius Traylor Schoenbaum

LSU Doctoral Dissertations

Motivated by potential applications to theoretical computer science, in particular those areas where the Curry-Howard correspondence plays an important role, as well as by the ongoing search in pure mathematics for feasible approaches to higher category theory, we undertake a detailed study of a new mathematical abstraction, the generalized category. It is a partially defined monoid equipped with endomorphism maps defining sources and targets on arbitrary elements, possibly allowing a proximal behavior with respect to composition. We first present a formal introduction to the theory of generalized categories. We describe functors, equivalences, natural transformations, adjoints, and limits in the generalized …

Exploration Of Bimetallic Nickel And Cobalt Complexes For Catalytic Oxidative Cleavage Of Alkenes And Hydroformylation, Ciera Vonn Duronslet

LSU Doctoral Dissertations

The “old” bimetallic nickel complexes, meso- and rac-Ni2Cl4(et,ph-P4) were investigated as possible “catalysts” for the oxidative cleavage of alkenes using an unsaturated fatty acid, oleic acid, as the substrate. The “new” bimetallic nickel complexes with a stronger chelating tetraphosphine ligand, meso- and rac-Ni2Cl4(et,ph-P4-Ph), were also synthesized and tested for the oxidative cleavage of oleic acid. All four dinickel complexes were found to be active for the oxidative cleavage of oleic acid, producing extremely small amounts of aldehyde product. The Stanley research group also discovered the oxidative cleavage of alkenes using only the “old” et,ph-P4 tetraphosphine ligands with no metal centers. …

Synthesis And Characterization Of Cyclic Polypeptoids By Organo-Mediated Controlled Zwitterionic Ring-Opening Polymerization And Development Of Redox-Responsive Polypeptoid Micelles As Drug Delivery Carriers, Ang Li

LSU Doctoral Dissertations

Peptoids are peptidomimetic polymers, which have attracted much attention over the past two decades. They have similar building blocks to peptides, and the similarity makes the backbone of peptoids hydrophilic and biocompatible.1 Two types of peptoid polymers are under development. One is sequence-defined peptoids, which exhibit excellent bioactivities.2 Another one is polypeptoids. The good biocompatibility and highly tunable side chain substituents allow polypeptoids to be used broadly in future biomedical applications. Varying polymer architectures, including linear polymers, cyclic polymers, comb-like polymers, and dendrimers can provide distinctive properties to the polymers. Cyclic polymers employ a cyclic architecture and lack chain ends, …

Advanced Monte Carlo Methods For The Study Of Nucleation, Troy David Loeffler

LSU Doctoral Dissertations

The process of nucleation is an essential part of understanding and controlling phase changes in a wide array of systems. In the past theories such as Classical Nucleation Theory have been used as a tool to aid experimentalist in the study of phase mechanisms. However, recent studies have shown in detail that theories such as this are not reliable, given that it can mispredict nucleation rates by several orders of magnitude. As a result newer methodologies must be developed into order to improve upon these deficiencies. In this study we use atomistic simulations to examine the non-ideal deviations from classical …

Simulation Studies For Relative Importance Of Unconventional Reservoir Subgrid Scale Physics Parameters, Yaakoub Youssef El Khamra

LSU Doctoral Dissertations

In this endeavor we attempt to better understand gas transport in shale gas reservoirs, specifically the impact and effects of different physical phenomena. We start by documenting the nature of the reservoirs and the need for accurate modeling of various physical phenomena in multiple interconnected continua. The physical phenomena of interest include non-linear Forchheimer flow, Knudsen diffusion in the form of slip "Klinkenberg" flow and adsorption/desorption. The numerical methods used in the reservoir simulator are also introduced, along with a derivation of the main equations used. Various verification and validation results are compared against manufactured and analytical solutions and finally …