Digital Commons Network^™

A Trust-Based Relay Selection Approach To The Multi-Hop Network Formation Problem In Cognitive Radio Networks, Brandy Michelle Tyson

LSU Doctoral Dissertations

One of the major challenges for today’s wireless communications is to meet the growing demand for supporting an increasing diversity of wireless applications with limited spectrum resource. In cooperative communications and networking, users share resources and collaborate in a distributed approach, similar to entities of active social groups in self organizational communities. Users’ information may be shared by the user and also by the cooperative users, in distributed transmission. Cooperative communications and networking is a fairly new communication paradigm that promises significant capacity and multiplexing gain increase in wireless networks. This research will provide a cooperative relay selection framework that …

Holecene Paleoenvironmental Reconstruction From The Shark River Estuary, Everglades, Florida, Qiang Yao

LSU Doctoral Dissertations

This dissertation examines the paleoecological records from the Shark River Estuary in the southwestern part of the Everglades National Park (ENP), Florida, with primary goal of reconstructing the Holocene history of the coastal mangrove ecosystem in the Florida Coastal Everglades. Roughly 15 meters of sediments were collected from 4 study sites and subjected to loss-on ignition, palynological, and X-ray fluorescence analyses. According to the literature, the earliest communities of Rhizophora mangle (red mangrove) occurred prior to 8,000 cal yr BP in the south-central area of the Belize Barrier Reef Platform. Between 7,000 and 5,000 cal yr BP, Rhizophora was established …

First-Principles And Many-Body Methods: Implementations And Applications To Study Spintronic Materials, Ryky Nelson

LSU Doctoral Dissertations

Diluted magnetic semiconductors (DMSs) and magnetoresistive materials are instrumental for the development of spintronic technology. Before we are able to engineer spintronic devices, it is necessary to understand the properties of materials from which spintronic devices are made, otherwise time and other resources will be wasted. In this thesis, we investigate some aspects of diluted magnetic semiconductors and a magnetoresistive material Ta2PdSe6 with first-principle and many-body methods. Particularly, we investigate the Mn valence in (Ga,Mn)N and derive low-energy models of (Ga,Mn)N by making use of a first-principles Wannier-function analysis. Additionally, we also study the disorder-driven localization in DMSs with the …

Photoelectrons And Recombining Electrons In Atomic And Molecular Systems, Kristen D'Ann Fulfer

LSU Doctoral Dissertations

This work in this dissertation explores how photoelectrons enter and exit atoms and molecules. The electron rescattering events which may occur during photoionization or photorecombination processes play a dominant role in the understanding of how photoelectrons enter and exit molecules, which is intrinsically linked to how chemical reactions occur. Chapters 3-4 of this dissertation present evidence of vibrational mode specific breakdown of the Franck-Condon Principle in the photoionization of low symmetry molecules, acrolein and the singly halogenated thiophenes, due to resonant and non-resonant electron rescattering dynamics. In Chapters 5-6, the disentanglement of the valence electronic structure, as well as evidence …

Optimized Aperiodic Multilayer Structures For Absorbers And Thermal Emitters, Christopher H. Granier

LSU Doctoral Dissertations

In this dissertation, we begin with a brief introduction to nanophotonics. In particular, we will focus on the theory of computational electricity and magnetism, specifically, the method used for this research, the transfer-matrix method. We will also provide discussions of the principles which motivate the analysis of the multilayer structures: Planck's blackbody distribution, Kirchoff's law, and thermodynamics. Finally, we will provide a brief discussion of computer-based optimization algorithms, specifically NLOPT (a library which provides computational packages for nonlinear optimization) and genetic algorithms. This background information is necessary to understand discussions which occur in later chapters.

Chapter 2 will discuss multilayer …

Exploring Superconductivity In Chiral Structured Aube, Drew Jared Rebar

LSU Doctoral Dissertations

AuBe is a noncentrosymmetric superconductor with the B20 FeSi-type structure. Noncentrosymmetric superconductors are expected to give rise to unconventional superconductivity due to spin orbit coupling and a mixed spin-singlet, spin-triplet state. The B20 structure of AuBe is particularly interesting since this is one of the only known crystal structures for bulk magnetic skyrmions in materials such as MnSi and Cu2OSeO3. The superconducting state was characterized by specific heat, dc magnetization, ac susceptibility, and resistivity. Specific heat revealed AuBe to host an isotropic gap characteristic of predominantly s-wave spin-singlet pairing in the weak coupling limit. Magnetization and susceptibility measurements revealed a …

Well-Quasi-Ordering By The Induced-Minor Relation, Chanun Lewchalermvongs

LSU Doctoral Dissertations

Robertson and Seymour proved Wagner's Conjecture, which says that finite graphs are well-quasi-ordered by the minor relation. Their work motivates the question as to whether any class of graphs is well-quasi-ordered by other containment relations. This dissertation is concerned with a special graph containment relation, the induced-minor relation. This dissertation begins with a brief introduction to various graph containment relations and their connections with well-quasi-ordering. In the first chapter, we discuss the results about well-quasi-ordering by graph containment relations and the main problems of this dissertation. The graph theory terminology and preliminary results that will be used are presented in …

Development Of Transition Metal-Catalyzed Polymerization Reactions And Their Applications For The Preparation Of Well-Defined Conjugated Polymer Architectures, Carlos Anthony Chavez

LSU Doctoral Dissertations

The synthesis of conjugated polymers and design of complex materials based on them have become increasingly popular as the demand for low-cost efficient and processible optoelectronic and semiconducting devices escalates. While advanced applications of polymeric materials require some degree of sophistication, success can be achieved through careful consideration of polymerization techniques and methodologies. Controlling critical aspects of the polymerization process allows for synthesis of complex macromolecular architectures possessing unique and novel properties that may be worth of further comprehensive investigation. This dissertation primarily focuses on the development and preparation of well-defined hierarchical macromolecular architectures. The foundation of this work encompasses …

Rényi Quantum Conditional Mutual Information And Parity Quantum Optical Metrology, Kaushik Parasuram Seshadreesan

LSU Doctoral Dissertations

This is a two-part thesis strung together by a common underlying theme—quantum correlations. We present some new characterizations and quantifications of quantum correlations and an application of one such correlation—entanglement—for quantum technology.

In Part I of the thesis, we use a Rényi generalization of the quantum conditional mutual information (QCMI) to define and study new measures of quantum entanglement and quantum discord. In particular, using a quantity derived from a Rényi QCMI, we introduce: a) the geometric squashed entanglement, a faithful entanglement measure, which is a lower bound on the squashed entanglement and which reduces to the geometric measure of …

Design And Validation Of A Prototype Collimation System With Reduced Applicator Weights For Elekta Electron Therapy Beams, Garrett Michael Pitcher

LSU Doctoral Dissertations

The objective of this study was to design an electron collimation system for Elekta Infinity accelerators with significantly reduced applicator weights, while maintaining acceptable in-field beam flatness and out-of-field leakage dose. The design was restricted to 6-20 MeV beams for 6x6 to 25x25 cm2 applicators at 100 cm SSD with the MLCi2 treatment head. In Aim1, measured off-axis profiles showed that the current Elekta collimation system met dose flatness (4%) and IEC leakage dose specifications in the patient plane for custom 7, 13, and 20 MeV beams at MBPCC. Also, Monte Carlo (MC) calculations based on MBPCC beam models sufficiently …

Wavelets, Coorbit Theory, And Projective Representations, Amer Hasan Darweesh

LSU Doctoral Dissertations

Banach spaces of functions, or more generally, of distributions are one of the main topics in analysis. In this thesis, we present an abstract framework for construction of invariant Banach function spaces from projective group representations. Coorbit theory gives a unified method to construct invariant Banach function spaces via representations of Lie groups. This theory was introduced by \Fch\, and \Gro\, in \cite{FG,FG1, FG2,FG3} and then extended in \cite{CO2}. We generalize this concept by constructing coorbit spaces using projective representation which is first studied by O. Christensen in \cite{O1}. This allows us to describe wider classes of function spaces as …

Developing Recognition Criteria For Current-Wave-Enhanced Sediment Gravity Flows, Kathryn Christine Denommee

LSU Doctoral Dissertations

Sedimentary fabrics preserved in the rock record provide some of the best evidence for interpreting paleo-depositional conditions. Muddy sediments in particular are important paleoenvironmental archives, preserving the most complete stratigraphic record of any rock type in basinal settings. However, the full range of mechanisms responsible for the deposition of muddy sediments, particularly in high-energy settings, remains poorly understood. Although frequently observed in modern settings, muddy prodeltaic deposits are rarely identified in the rock record, in part because no catalogue of easily distinguishable recognition criteria exists for this class of mudstones. In order to help overcome this deficiency, this dissertation project …

Synthetic Methods Development Towards The Total Synthesis Of Chlorosulfolipids, Andres Villalpando

LSU Doctoral Dissertations

The focus of this dissertation is the development of a novel chlorination reaction utilizing a triphosgene-amine based mixture towards the total synthesis of chlorosulfolipids, a subclass of naturally occurring organohalogen natural products. This novel, mild chlorination reaction will be utilized under a global chlorination strategy to chlorinate multiple alcohol substituents in one synthetic operation. Chapter one details the history of chlorosulfolipids from the early stages of their isolation, relevant structural elucidation techniques, appropriate biosynthetic discoveries, and their biological relevance to a thorough investigation of the total syntheses completed to date. These compounds demonstrate a range of biological activities and have …

On The Development Of Analytical Methodologies To Interrogate The Lipid Dynamics And Phase Transition Resulting From The Reduction Of Stimuli-Responsive Vesicles, James Edward Winter

LSU Doctoral Dissertations

The potential is great for liposome drug delivery systems that provide specific contents release at diseased tissue sites upon activation by upregulated enzymes; however, this potential will only come to fruition with mechanistic knowledge of the contents release process. NAD(P)H:quinone oxidoreductase type 1 (NQO1) is a target for reductively-responsive liposomes, as it is an enzyme upregulated in numerous cancer tissues and is capable of reducing quinone propionic acid (QPA) trigger groups to hydroquinones that self-cleave from dioleolylphosphatidylethanolamine (DOPE) liposome surfaces, thereby initiating contents release. This research targets the development of analytical methodologies to observe and characterize the dynamics and resulting …

Design And Application Of Task-Specific Organic Salts For Chemical And Biochemical Sensing, Waduge Indika Subodha Galpothdeniya

LSU Doctoral Dissertations

There is an increasing demand for development of new sensors and sensor strategies for accurate detection and discrimination of various analytes. In this regard, colorimetric and fluorometric sensor approaches have attracted considerable attention, primarily because they represent facile and inexpensive analytical tools. In this dissertation, I discuss the design and application of sensors and sensor arrays using task specific organic salts: ionic liquids (ILs) and a group of uniform materials based on organic salts (GUMBOS). As compared to typical ionic compounds, these two classes of organic salts exhibit relatively lower melting points due to bulky organic cations and/or anions. Interestingly, …

Platinum Complexes With Tridentate Ligands As Models For Active Monofunctional Anticancer Drugs, Chase Koby Andrepont

LSU Doctoral Dissertations

Pt(II) complexes bind preferentially at N7 of G residues of DNA, causing DNA structural distortions associated with anticancer activity. Some distortions induced by difunctional cisplatin are also found for monofunctional Pt(II) complexes with carrier ligands having bulk projecting toward the guanine base. This ligand bulk can be correlated with impeded rotation about the Pt–N7(guanine) bond. The objective of this study is to understand the influences of in-plane bulk of Pt(Ltri)G adducts (Ltri = tridentate carrier ligand, G = guanine derivative bound to a metal, but not tethered to another nucleobase). NMR spectroscopy provided conclusive evidence that Pt(Ltri)G (Ltri = di-(2-picolyl)amine …

Synergistic Properties-Driven Synthesis Of Aluminides, Antiomonides, And Bioceramics, Pilanda Watkins-Curry

LSU Doctoral Dissertations

The synthesis, characterization, and properties of selected intermetallics and ceramic materials are presented in this dissertation. In our quest to grow single crystal intermetallics from the metal flux technique, new strategies were employed to avoid thermodynamically stable phases and to ensure sample homogeneity of the crystalline product for structure elucidation and accurate measurements of their magnetic and electrical properties. The relationship between the complex crystal structures and magnetic properties are reported for LnCo2Al8 (Ln = La-Nd, Sm, Yb), CeCo2-xMnxAl8 (0 < x < 1), and Pr2Fe4-xCoxSb5 (1 ≤ x < 3). The discovery of magnetic frustration in LnCo2Al8 (Ln = Ce, Nd) and complex magnetic ordering coupled with large positive magnetoresistance of up to 150% and 60% at 200 K with relatively low field of H = 1 T in Pr2Fe4-xCoxSb5 (x ≈ 2 and 2.5) is also reported. The demand of new inorganic solid materials as scaffolds for the engineering of bone tissue has led to the synthesis of calcium magnesium silicates such as, diopside (CaMgSi2O6), akermanite (Ca2MgSi2O7), monticellite (CaMgSiO4), and merwinite (Ca3Mg(SiO4)2)) for studying dimensionality and mechanical properties. This dissertation highlights the synergism of solid state chemistry at the interface of condensed matter physics and biological engineering. The discovery of compounds with tunable magnetic, electrical, and mechanical properties will be described herein.

I. Synthesis Of Ascarosides For Chemical Biology Studies In Caenorhabditis Elegans, Ii. A Photochemical Approach To Delavayine, And Iii. Remote Hydroxylation By Radical Translocation And Polar Crossover, Kyle Allen Hollister

LSU Doctoral Dissertations

The foci of this dissertation are the synthesis of analogs for chemical biology studies, synthetic chemistry method development (with an emphasis on photochemistry), and the application of these methods toward total synthesis. Chapter 1 outlines the synthesis of an array of pheromone analogs that are derivatives of the dideoxy sugar ascarylose. Referred to as ascarosides, such compounds have recently been shown to influence important biological processes in the model organism Caenorhabditis elegans. C. elegans secretes ascarosides into its environment, where the compounds then act as signaling molecules by providing information on factors like population density. Chapter 2 describes the biological …

Nanoscale Gumbos: Size-Control, Characterization, And Applications As Enantioselective Molecularly Imprinted Polymers And Fluorescent Materials, Suzana Hamdan

LSU Doctoral Dissertations

Nanomaterials derived from a group of uniform materials based on organic salts (GUMBOS) have been introduced into the scientific literature through many analytical, biological, and technological applications. These nanomaterials, referred to as nanoGUMBOS, have been shown to display a number of interesting properties including fluorescence, magnetism, tumor targeting, and optoelectronic properties. Herein, we present major studies on nanoGUMBOS including synthesis and size-control, chiral molecular imprinting in polymers, as well as investigation of optical properties and quantum yield of fluorescent semiconductor-based nanoGUMBOS. Various strategies were introduced for production of well-defined nanoGUMBOS. Specifically, several methods based on sonochemistry, microwave, cyclodextrin, and surfactant-assisted …

Analysis Of Nonlinear Dispersive Model Equations, Jacob Grey

LSU Doctoral Dissertations

In this work we begin with a brief survey of the classical fluid dynamics problem of water waves, and then proceed to derive well known evolution equations via a Hamiltonian Variational approach. This method was first introduced in the seminal work of Walter Craig, et al. \cite{CG}. The distinguishing feature of this scheme is that the Dirichlet-Neumann operator of the fluid domain appears explicitly in the Hamiltonian. In the second and third chapters, we utilize the Hamiltonian perturbation theory introduced in \cite{CG} to derive the Benjamin-Bona-Mahony (BBM) and Benjamin-Bona-Mahony-Kadomtsev-Petviashvili (BBM-KP)equations. Finally, we briefly review the existence theory for their corresponding …

String Searching With Ranking Constraints And Uncertainty, Sudip Biswas

LSU Doctoral Dissertations

Strings play an important role in many areas of computer science. Searching pattern in a string or string collection is one of the most classic problems. Different variations of this problem such as document retrieval, ranked document retrieval, dictionary matching has been well studied. Enormous growth of internet, large genomic projects, sensor networks, digital libraries necessitates not just efficient algorithms and data structures for the general string indexing, but indexes for texts with fuzzy information and support for queries with different constraints. This dissertation addresses some of these problems and proposes indexing solutions. One such variation is document retrieval query …

Scanning Probe Investigations Of Nanopatterned And Thermo-Responsive Polypeptoids And The Design Of A Sample Stage For Force Modulation Microscopy, Lu Lu

LSU Doctoral Dissertations

Protocols for patterning nanostructures of polymers were developed to enable scanning probe microscopy (SPM) studies of surface properties at the molecular level. A chemically selective surface for patterning polymers was generated by combining particle lithography with organosilane immersion. Poly(N-allyl glycine), a biocompatible and backbone degradable polypeptoid, was grown on Si(111) at confined amine sites using surface-initiated polymerization (also known as the “graft from” approach). A thermo-responsive random copolypeptoid, poly[(N-ethyl glycine)32-r-(N-butyl glycine17)], was pre-synthesized and attached onto a patterned organosilane surface using a thiol-ene click reaction (“graft to” approach). The phase transitions of the copolypeptoid nanostructures in an aqueous environment was …

Cellulose Nanofibers From Energycane Bagasse And Their Applications In Core-Shell Structured Hydrogels, Yiying Yue

LSU Doctoral Dissertations

Cellulose fibers (Cellulose I, cellulose II and cellulose I/II Hybrid fibers) were successfully extracted from energycane bagasse by using a combined NaOH and NaClO2 treatment. After the delignification process, most lignin and hemicellulose were removed with a 27.4wt% yield of cellulose fibers, and the mean diameter of cellulose fibers decreased from 137±46 (raw fiber bundles) to 12±5μm (unpacked fibers). The raw bagasse fibers showed a three-step pyrolysis process, while isolated cellulose fibers had a one-step pyrolysis process. NaClO2 treatment caused the reduction of cellulose thermal stability due to its acting on lignin and cellulose. With 10h NaOH treatment, the ribbon …

A New Method In Distribution Theory With A Non-Smooth Framework, Yunyun Yang

LSU Doctoral Dissertations

In this work, we present a complete treatment of the theory of thick distributions and its asymptotic expansion. We also present several applications of thick distributions in mathematical physics, function spaces, and measure theory. We also discuss regularization using different surfaces. In the last chapter we present some recent applications of distributions in clarifying the moment terms in the heat kernel expansion, and in explaining the relation between the heat kernel expansion and the cylinder kernel expansion.

Left-Orderability, Cyclic Branched Covers And Representations Of The Knot Group, Ying Hu

LSU Doctoral Dissertations

A group G is called left-orderable if one can find a total order on G, which is preserved under left multiplication. In this paper we first give a sufficient condition for the fundamental group of the nth cyclic branched cover of the three sphere over a prime knot K to be left-orderable, in terms of representations of the knot group. Then we make use of this criterion to study the left-orderability of fundamental groups of cyclic branched covers over two-bridge knots and satellite knots.

Gumbos As Matrices For Matrix-Assisted Laser Desorption Ionization Time Of Flight Mass Spectrometry, Hashim Abdullah Al Ghafly

LSU Doctoral Dissertations

This work involves the investigation of a group of uniform materials based on organic salts (GUMBOS) as matrices for matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF) for analysis of hydrophobic biomolecules. GUMBOS are new class of materials that show great promise as MALDI matrices because they are able to form a thin-layer on the MS target, thereby enhancing the sample homogeneity, signal intensity, and shot-to-shot reproducibility. The detection of hydrophobic peptides using MALDI-TOF MS remains a challenge because the majority of matrices utilized are hydrophilic thereby exhibiting low affinity for hydrophobic molecules. To address this, I …

Attosecond Transient Absorption In Gases And High Harmonic Generation In Solids, Mengxi Wu

LSU Doctoral Dissertations

We present a theoretical study of attosecond transient absorption in gases and high harmonic generation in solids. In this thesis, different features in the attosecond transient absorption laser-dressed spectrum are studied, including features near bright (dipole allowed) atomic states and features that appear approximately one or two laser photons away from the bright states due to the laser-induced coupling to dark (non-dipole allowed) states. The calculations are carried out using both numerical and analytic solutions to the time-dependent Schr\"odinger equation (TDSE). From these solutions, several models of time-dependent absorption and electron dynamics at the femtosecond time scale are presented. We …

Single Molecule Electrophoresis And Optical Detection Using Thermoplastic Nanofluidic Devices: An Experimental And Simulation Study, Kumuditha Madushanka Weerakoon Ratnayake

LSU Doctoral Dissertations

Nanofludic devices provide a great platform for single molecular analysis. The unique phenomena in nanoscale gained such interest in investigating the single molecular behavior in nanochannels. Sizes less than 200 nm in one or two-dimensional structures have lead to fascinating observations not accessible in microscale. When a single molecule translocates through a nanotube it interacts with channel walls by adsorption/ desorption, van der Waals interactions and hydrophilic interactions providing a mechanism for separation without any extra additives. Moreover, double layer thickness governed by the background electrolyte plays a vital role. We report single molecular electrophoresis phenomena in nanochannels and nanoslits …

Anisotropic Spacetimes And Black Hole Interiors In Loop Quantum Gravity, Anton Joe

LSU Doctoral Dissertations

This thesis deals with understanding quantum gravitational effects in those anisotropic spacetimes which serve as black hole interiors. Two types of spacetime are investigated. Kantowski-Sachs spacetime and Bianchi-III LRS spacetime. The former, in vacuum, is the interor spacetime for Schwarzschild black holes. The latter is the interior for higher genus black holes. These spacetimes are studied in the context of loop quantum cosmology. Using effective dynamics of loop quantum cosmology, the behavior of expansion and shear scalars in different proposed quantizations of the Kantowski-Sachs spacetime with matter is investigated. It is found that out of the various proposed choices, there …

Nuclear Structure Of 26si And 32cl For Astrophysics, Liudmyla Afanasieva

LSU Doctoral Dissertations

We studied the nuclear structure of two isotopes, 26Si and 32Cl, important for understanding stellar explosions like novae and Type I X-ray bursts. The 31S(p,γ)32Cl reaction rate influences the enrichment of sulfur observed in some nova ejecta, but the uncertainty in the rate spans as much as an order of magnitude and arises from uncertainties in the properties of resonances corresponding to excited states in 32Cl. We populated states in 32Cl via the 10B(24Mg,2n)32Cl reaction using the Argonne Tandem-Linac Accelerator System (ATLAS), with a 75 MeV beam of 24Mg bombarding a 200 μg/cm2 10B target. Gamma rays emitted from recoiling …