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LSU Doctoral Dissertations

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Full-Text Articles in Physical Sciences and Mathematics

Experience-Based Language Acquisition: A Computational Model Of Human Language Acquisition, Brian Edward Pangburn Jan 2002

Experience-Based Language Acquisition: A Computational Model Of Human Language Acquisition, Brian Edward Pangburn

LSU Doctoral Dissertations

Almost from the very beginning of the digital age, people have sought better ways to communicate with computers. This research investigates how computers might be enabled to understand natural language in a more humanlike way. Based, in part, on cognitive development in infants, we introduce an open computational framework for visual perception and grounded language acquisition called Experience-Based Language Acquisition (EBLA). EBLA can “watch” a series of short videos and acquire a simple language of nouns and verbs corresponding to the objects and object-object relations in those videos. Upon acquiring this protolanguage, EBLA can perform basic scene analysis to generate …


Precursors For Copper Chemical Vapor Deposition, Muna Bufaroosha Jan 2002

Precursors For Copper Chemical Vapor Deposition, Muna Bufaroosha

LSU Doctoral Dissertations

The main objective of this study was to synthesize precursors that are capable of producing copper films of high quality by chemical vapor deposition (CVD). We investigated some copper(I) and copper(II) complexes as precursors for chemical or photochemical vapor deposition. In chapter 2, we synthesized a series of Cu(hfac)2(amine) adducts, where hfac- is hexafluoroacetylacetonate and the amines are: dimethylamine, isopropylamine, allylamine, pyrrolidine, and piperidine. The efficiency of these adducts compared to Cu(hfac)2(H2O) as Cu-CVD precursors was examined under hydrogen. We found that among these amine adducts, Cu(hfac)2(allylamine)2 gave the best …


Mode Specific Photoionization Dynamics In Polyatomic Molecules, Gerald Jeffery Rathbone Jan 2002

Mode Specific Photoionization Dynamics In Polyatomic Molecules, Gerald Jeffery Rathbone

LSU Doctoral Dissertations

The work presented in this dissertation presents new work on polyatomic photoionization. In these investigations, the broad range behavior of both allowed and forbidden vibrational modes in linear triatomic systems were studied to understand mode specific aspects of photoionization. The current study is made possible by the experimental strategy of exploiting high resolution photoelectron spectroscopy and the high brightness of third generation synchrotron radiation sources. The data is taken typically tens of eV’s past the ionization potential. The strategy that I employ is to probe alternative vibrational modes which are frequently affected differently following resonant ionization. Such vibrationally resolved data …


Nonlinear Dynamics In Nuclear Structure, Guergana Stoianova Stoitcheva Jan 2002

Nonlinear Dynamics In Nuclear Structure, Guergana Stoianova Stoitcheva

LSU Doctoral Dissertations

New collective coordinates that describe the deformation of atomic nuclei in terms of solitary waves (rotons) that are solutions of an underlying nonlinear liquid drop dynamics are introduced. The rotons, which are highly localized surface excitations, are shown to be intelligent states of an underlying angular momentum algebra, and furthermore, to adiabatically decouple from the rotational motion of the nucleus. An expansion of the roton profile in terms of surface multipoles shows that although the quadrupole mode (&lambda= 2) dominates, there are significant contributions from other even multipoles with &lambda= 4, 6, 8, etc. The picture of nuclear deformation that …


The Ligase Detection Reaction: The Evolution Of A Mutation Detection Strategy, Hannah D. Farquar Jan 2002

The Ligase Detection Reaction: The Evolution Of A Mutation Detection Strategy, Hannah D. Farquar

LSU Doctoral Dissertations

Early detection of genetic mutations is important for control of diseases such as cancer and Alzheimer's. Early detection requires methods that detect small amounts of mutated DNA in very large amounts of normal or wild type DNA. One method to detect mutated DNA is the ligase detection reaction (LDR). Since its inception LDR has evolved greatly from a simple detection reaction after PCR amplification to PCR/RE/LDR, a scheme which uses nucleoside base analogs in PCR to convert wild type sequences to sequences containing restriction endonuclease (RE) sites which can then be cleaved leaving only mutant sequences for detection by LDR. …


Mixed-Symmetry Shell-Model Calculations In Nuclear Physics, Vesselin Gueorguiev Gueorguiev Jan 2002

Mixed-Symmetry Shell-Model Calculations In Nuclear Physics, Vesselin Gueorguiev Gueorguiev

LSU Doctoral Dissertations

Advances in computer technologies allow calculations in ever larger model spaces. To keep our understanding growing along with this growth in computational power, we consider a novel approach to the nuclear shell model. The one-dimensional harmonic oscillator in a box is used to introduce the concept of an oblique-basis shell-model theory. By implementing the Lanczos method for diagonalization of large matrices, and the Cholesky algorithm for solving generalized eigenvalue problems, the method is applied to nuclei. The mixed-symmetry basis combines traditional spherical shell-model states with SU(3) collective configurations. We test the validity of this mixed-symmetry scheme on 24Mg and …


Ontogeny And Intervals Of Development In Five Reef-Associated Species Of Blenny From The Northern Gulf Of Mexico (Teleostei: Blenniidae), James G. Ditty Jan 2002

Ontogeny And Intervals Of Development In Five Reef-Associated Species Of Blenny From The Northern Gulf Of Mexico (Teleostei: Blenniidae), James G. Ditty

LSU Doctoral Dissertations

I examined patterns and timing of ontogeny and relative growth in five species of blenny (Teleostei: Blenniidae) from the northern Gulf of Mexico by assigning a suite of discrete character state scores to ontogenetic events (10 external traits; 218 total specimens). This is the first study to evaluate developmental patterns in reef-associated fishes relative to the timing of metamorphosis and settlement by applying scaling techniques and statistical methods to quantify, differentiate, and select criteria for defining intervals of development across taxa. Blennies settle at a common state of ontogeny and share a common pattern of body and fin/cirrus growth. Three …


Fast Scalable Visualization Techniques For Interactive Billion-Particle Walkthrough, Xinlian Liu Jan 2002

Fast Scalable Visualization Techniques For Interactive Billion-Particle Walkthrough, Xinlian Liu

LSU Doctoral Dissertations

This research develops a comprehensive framework for interactive walkthrough involving one billion particles in an immersive virtual environment to enable interrogative visualization of large atomistic simulation data. As a mixture of scientific and engineering approaches, the framework is based on four key techniques: adaptive data compression based on space-filling curves, octree-based visibility and occlusion culling, predictive caching based on machine learning, and scalable data reduction based on parallel and distributed processing. In terms of parallel rendering, this system combines functional parallelism, data parallelism, and temporal parallelism to improve interactivity. The visualization framework will be applicable not only to material simulation, …


Molecular Dynamics Simulations Of Adhesion And Nanoidentation Of Gallium Arsenide, Francis Brent Neal, Jr. Jan 2002

Molecular Dynamics Simulations Of Adhesion And Nanoidentation Of Gallium Arsenide, Francis Brent Neal, Jr.

LSU Doctoral Dissertations

The purpose of this dissertation is to investigate the nanoscale hardness of gallium arsenide thin films and the elastic-plastic behavior of gallium arsenide under an indenter. These investigations were carried out using molecular dynamics (MD) simulations. The simulations are based on interatomic potentials that accurately reproduce many properties of bulk GaAs. The MD simulations performed required scalable and efficient algorithms for implementation on large parallel computers. Nanoindentation simulations were performed using an ideal indenter that was held rigid during the simulation. To reduce the transient effects due to loading, the traversal of the indenter was interrupted periodically to allow the …


Peroxynitrite-Mediated Oxidations: Nitration And Nitrosation, Rachel Bolzan Jan 2002

Peroxynitrite-Mediated Oxidations: Nitration And Nitrosation, Rachel Bolzan

LSU Doctoral Dissertations

Using a direct ultraviolet second-derivative spectroscopy method, three peroxynitrite preparative methods were investigated for the nitrite and nitrate present either as impurities or produced during peroxynitrite decomposition: (I) ozonation of azide, reaction of hydrogen peroxide with (II) isoamyl nitrite and (III) nitrous acid. The oxidation of morpholine by peroxynitrite in the presence and absence of added carbonate gives N-nitromorpholine and N-nitrosomorpholine. Nitration and nitrosation of morpholine are catalyzed by low levels of CO2; however, excess CO2 dramatically reduces the yields of nitrosation but not nitration, and the combined yields of the products are about the same under …


The Combined Effects Of Salinity And Sulfide On The Growth And Physiology Of The Freshwater Marsh Plant Pancium Hemitomon J.A. Schultes, James Wesley Pahl Jan 2002

The Combined Effects Of Salinity And Sulfide On The Growth And Physiology Of The Freshwater Marsh Plant Pancium Hemitomon J.A. Schultes, James Wesley Pahl

LSU Doctoral Dissertations

Vegetative response to saltwater intrusion into coastal freshwater wetlands is governed by the combined effects of increased salinity and porewater sulfide concentrations. I conducted a series of experiments to address the primary hypothesis that growth of Panicum hemitomon is adversely affected by an interaction between salinity and sulfide stresses associated with saltwater intrusion, and the mechanisms for decreased growth are alterations in the metabolic and morphological adaptations needed for a plant to survive in a flooded environment. I exposed marsh sods to a factorial treatment arrangement of three salinities (0, 2, and 4 ppt) and three porewater sulfide concentrations (0, …


Tidal Dynamics In The Bab El Mandab Strait, Ewa Jarosz Jan 2002

Tidal Dynamics In The Bab El Mandab Strait, Ewa Jarosz

LSU Doctoral Dissertations

The Bab el Mandab Strait is where the transition occurs between two noticeably different tidal regimes: the Gulf of Aden, where tidal fluctuations are mixed and have a range in excess of 2 m, and the Red Sea, where the tides are principally semidiurnal and their range is less than 1 m. Within the Strait, observations collected between May of 1995 and July of 1997 indicate that tidal currents are a mixed type and dominant constituents are the K1 and M2. The vertical structure of the tidal currents is complicated, differs between semidiurnal and diurnal constituents, and …


A Monotone Follower Control Problem With A Nonconvex Functional And Some Related Problems, Jamiiru Luttamaguzi Jan 2002

A Monotone Follower Control Problem With A Nonconvex Functional And Some Related Problems, Jamiiru Luttamaguzi

LSU Doctoral Dissertations

A generalized one-dimensional monotone follower control problem with a nonconvex functional is considered. The controls are assumed to be nonnegative progressively measurable processes. The verification theorem for this problem is presented. A specific monotone follower control problem with a nonconvex functional is then considered in which the diffusion term is constant. The optimal control for this problem, which is explicitly given, can be viewed as tracking a standard Wiener process by a non anticipating process starting at 0. For some parameters values, the value function for this monotone follower control problem is shown to be C2 and for other …


On The Stabilization And Regularization Of Rational Approximation Schemes For Semigroups, Simone Flory Jan 2002

On The Stabilization And Regularization Of Rational Approximation Schemes For Semigroups, Simone Flory

LSU Doctoral Dissertations

In this work we discuss consistency, stability and convergence of rational approximation methods for strongly continuous semigroups on Banach spaces. The Lax-Chernoff theorem shows that in this setting consistency and stability assumptions are necessary to obtain strong uniform convergence of approximation methods. We investigate rational approximation methods for strongly continuous semigroups and their consistency properties, with special emphasis on A-stable methods and Padé-type approximations. In particular, we discuss the stability and convergence properties of these schemes, including the stability of the well-known and widely used Backward-Euler and Crank-Nicolson Schemes. Furthermore, we modify stabilization techniques developed by Hansbo, Larsson, Luskin, Rannacher, …


Artificial Peptides Containing Ca,A- Disubstituted Amino Acids: Synthesis, Conformational Studies, And Application As Β-Strand Mimics, Yanwen Fu Jan 2002

Artificial Peptides Containing Ca,A- Disubstituted Amino Acids: Synthesis, Conformational Studies, And Application As Β-Strand Mimics, Yanwen Fu

LSU Doctoral Dissertations

Short peptides containing Cα,α-dipropylglycine (Dpg) at alternating sequence positions were synthesized and examined for conformational behavior. Peptide assembly was performed using Fmoc-solid-phase chemistry where the coupling with PyAOP could be significantly enhanced at elevated temperature. Circular dichroism (CD) and NMR conformational studies revealed that incorporation of Dpg residues induced folded structures into peptides. It was observed that Dpg residues adopted helical conformation in a helix-promoting sequence. The resulting helical structure was comprised of consecutive β-turns whose structure was stabilized by salt bridge in aqueous solution. In this study, the preparation of sterically and polyfunctional Cα,α-disubstituted amino …


Outcrop To Subsurface Stratigraphy Of The Pennsylvanian Hermosa Group Southern Paradox Basin U.S.A., Alan Lee Brown Jan 2002

Outcrop To Subsurface Stratigraphy Of The Pennsylvanian Hermosa Group Southern Paradox Basin U.S.A., Alan Lee Brown

LSU Doctoral Dissertations

Pennsylvanian (Desmoinesian) sedimentary rocks within the Paradox Basin Four Corners area of the western United States afford a unique opportunity to study the development of sedimentary successions in a complex marine to nonmarine depositional setting. The close association of thick intervals of nonmarine fan-delta facies adjacent to and in time equivalent position to marine carbonate-evaporite facies suggests complex relationships between the factors affecting deposition. Development of an effective scheme to differentiate the depositional signatures from within these sedimentary successions is the primary goal of this study. To achieve this goal, two objectives were pursued. The first was to calibrate the …


Exotic Integral Witt Equivalence Of Algebraic Number Fields, Changheon Kang Jan 2002

Exotic Integral Witt Equivalence Of Algebraic Number Fields, Changheon Kang

LSU Doctoral Dissertations

Two algebraic number fields K and L are said to be exotically integrally Witt equivalent if there is a ring isomorphism W(OK) ~ W(OL) between the Witt rings of the number rings OK and OL of K and L, respectively. This dissertation studies exotic integral Witt equivalence for totally complex number fields and gives necessary and sufficient conditions for exotic integral equivalence in two special classes of totally complex number fields.


Barium And Lithium In Foraminifera: Glacial-Interglacial Changes In The North Atlantic, Jenney M. Hall Jan 2002

Barium And Lithium In Foraminifera: Glacial-Interglacial Changes In The North Atlantic, Jenney M. Hall

LSU Doctoral Dissertations

The trace element content of calcareous foraminifera provides a powerful tool to the study of glacial-interglacial changes in the physical and chemical properties of the ocean. Foraminifera incorporate barium in direct proportion to its concentration in seawater. Using barium as a nutrient proxy, Ba/Ca in benthic Planulina wuellerstorfi is used to reconstruct changes in thermocline ventilation and mid-depth circulation in the North Atlantic during the last glacial and deglacial time. Rivers are concentrated in barium compared to surface seawater. Therefore, barium in planktonic Neogloboquadrina pachyderma is used to identify deglacial meltwater in the Arctic Ocean. Foraminiferal Li/Ca was analyzed to …


Explicit Multiplicative Relations Between Gauss Sums, Brian J. Murray Jan 2002

Explicit Multiplicative Relations Between Gauss Sums, Brian J. Murray

LSU Doctoral Dissertations

H.Hasse conjectured that all multiplicative relations between Gauss sums essentially follow from the Davenport-Hasse product formula and the norm relation for Gauss sums. While this is known to be false, very few counterexamples, now known as sign ambiguities, have been given. Here, we provide an explicit product formula giving an infinite class of new sign ambiguities and resolve the ambiguous sign in terms of the order of the ideal class of quadratic primes.


Branch, Crown, Tree And Stand Water Flux In An 180-Year-Old Loblolly Pine Plantation After Thinning, Fertilization, And Throughfall Exclusion Treatments, Shufang Yu Jan 2002

Branch, Crown, Tree And Stand Water Flux In An 180-Year-Old Loblolly Pine Plantation After Thinning, Fertilization, And Throughfall Exclusion Treatments, Shufang Yu

LSU Doctoral Dissertations

Branch and tree sap flux density (SFD) was measured to evaluate the effects of thinning, fertilization, and throughfall exclusion treatments on water use by loblolly pine (Pinus taeda L.) trees. Variations in SFD at different radial xylem depths were also examined to improve estimates of tree water use from sap flux density measured in the outer sapwood. This study was conducted in an 18-year-old loblolly pine plantation in central Louisiana in 1999. The results revealed that SFD was higher in the outer xylem than in the inner xylem and large trees had higher SFD than small trees. Thinning increased daily …


Synthesis And Properties Of Novel Macrocycles And Related Chromophoric Benzenoid Compounds, Jorge O. Escobedo Cordova Jan 2002

Synthesis And Properties Of Novel Macrocycles And Related Chromophoric Benzenoid Compounds, Jorge O. Escobedo Cordova

LSU Doctoral Dissertations

The synthesis and properties of some macrocyclic compounds of interest are presented. Resorcinarenes with functionalized conjugated rigid rods made of oligo-p-phenylenes would lead to an entirely new class of functional, soluble, well-defined architectures impacting a variety of multidisciplinary research efforts. The general synthetic design described in this document could be readly extrapolated to include other electronic systems such as heteroaromatics and polyenes. An extensive collaborative study of chromophore formation in resorcinarene solutions is also described here. The study reveals that upon oxidation, the reversible conversion to acyclic precursors occur first, and then these precursors undergo oxidation to quinoid-type compounds (xanthenes). …


Fabricating Microfluidic Devices In Polymers For Bioanalytica Applications, Sean M. Ford Jan 2002

Fabricating Microfluidic Devices In Polymers For Bioanalytica Applications, Sean M. Ford

LSU Doctoral Dissertations

The research presented in this document focuses on the fabrication, characterization and application of microfluidic systems fabricated in poly(methyl methacrylate) (PMMA) with the emphasis focused on the fabrication processing steps. Microfluidic devices were produced in PMMA using X-ray lithography. The fabrication methods investigated were sacrificial mask, polyimide membrane mask and embossing techniques. PMMA microfluidic devices fabricated using X-ray lithography were characterized using scanning electron microscopy (SEM) and optical microscopy, while analytical techniques such as electroosmotic flow determination, separations, and fluorescent microscopy were used to characterize fluid transport in these devices. A novel method for the heat annealing of PMMA to …


Electronic And Structural Properties Of Rare Gas Cation Clusters, Jose Alejandro Gascon Jan 2002

Electronic And Structural Properties Of Rare Gas Cation Clusters, Jose Alejandro Gascon

LSU Doctoral Dissertations

We study structure and ground and excited state properties of rare gas cation clusters, Rg+N, for N=3-60. The main goal is to understand how the positive charge is delocalized over the cluster and the relationship between cluster geometry and delocalization. He+N, Ar+N, and Xe+N are selected as representatives of the rare gas elements. We perform Monte Carlo simulations to obtain finite temperature properties of the energy spectrum. The Hamiltonian of the system is based on a semi-empirical model whose parameters are obtained through the fitting of experimental and calculated …


Hydrodynamics And Freshwater Diversion Within Barataria Basin, Dongho Park Jan 2002

Hydrodynamics And Freshwater Diversion Within Barataria Basin, Dongho Park

LSU Doctoral Dissertations

In order to understand the physical processes in the Barataria estuary, a previously developed two-dimensional, depth-integrated hydrodynamic model is applied to simulate estuarine processes. The equations for conservation of mass and momentum predict specific physical processes when forced by tidal and salinity variations at the open boundaries, wind forcing patterns, precipitation and evaporation over the model domain, and freshwater runoff as point sources. This study is focused on examining the impact of freshwater dispersion from the freshwater sources. Thus, a hydrologic model was developed to estimate runoff. Furthermore grid size was reduced, a new advective code added, and baroclinic effects …


Capillary And Microdevice Electrophoretic Tools For Genetic Analyses: Heteroduplex Analysis For Tuberculosis Drug Susceptibility And Ligase Detection Reaction For Colorectal Cancer Detection, Gloria Thomas Jan 2002

Capillary And Microdevice Electrophoretic Tools For Genetic Analyses: Heteroduplex Analysis For Tuberculosis Drug Susceptibility And Ligase Detection Reaction For Colorectal Cancer Detection, Gloria Thomas

LSU Doctoral Dissertations

The traditional format of electrophoresis, the slab gel, is quickly being replaced by capillary and microdevice platforms, which offer improvements in cost, resolution, speed, quantitation and automation in genetic analyses. These techniques also employ a variety of separation matrices while the slab gel is limited to agarose and polyacrylamide. The research presented here explores the use of these electrophoretic formats for the detection of single nucleotide mutations using two genetic models associated with human disease. Slab gel based heteroduplex analysis (HDA), a popular mutation scanning method, uses a specially designed universal heteroduplex generator (UHG) containing controlled variation to enhance the …


Synthesis And Study Of New Materials For The Visual Detection Of Biomolecules, Ming He Jan 2002

Synthesis And Study Of New Materials For The Visual Detection Of Biomolecules, Ming He

LSU Doctoral Dissertations

The visual determination of saccharides has been of interest for well over a century. Sugars are a relatively challenging class of compounds to analyze. They exhibit great structural similarity as well as transparency in the visible region. The sensing of specific saccharides could aid the monitoring of disease or industrial fermentation products. Herein I present new methods allowing for simple and rapid visual detection of sialic acid, fructose and a homologous series of prototypical neutral oligosaccharides, the linear maltodextrins, containing up to seven glucose residues. The new methods allow for selective color detection of fructose in a large excess of …


Techniques To Explore Time-Related Correlation In Large Datasets, Sumeet Dua Jan 2002

Techniques To Explore Time-Related Correlation In Large Datasets, Sumeet Dua

LSU Doctoral Dissertations

The next generation of database management and computing systems will be significantly complex with data distributed both in functionality and operation. The complexity arises, at least in part, due to data types involved and types of information request rendered by the database user. Time sequence databases are generated in many practical applications. Detecting similar sequences and subsequences within these databases is an important research area and has generated lot of interest recently. Previous studies in this area have concentrated on calculating similitude between (sub)sequences of equal sizes. The question of unequal sized (sub)sequence comparison to report similitude has been an …


Complexity And Heuristics In Ruled-Based Algorithmic Music Composition, Nigel Gwee Jan 2002

Complexity And Heuristics In Ruled-Based Algorithmic Music Composition, Nigel Gwee

LSU Doctoral Dissertations

Successful algorithmic music composition requires the efficient creation of works that reflect human preferences. In examining this key issue, we make two main contributions in this dissertation: analysis of the computational complexity of algorithmic music composition, and methods to produce music that approximates a commendable human effort. We use species counterpoint as our compositional model, wherein a set of stylistic and grammatical rules governs the search for suitable countermelodies to match a given melody. Our analysis of the complexity of rule-based music composition considers four different types of computational problems: decision, enumeration, number, and optimization. For restricted versions of the …


X-Ray Spectroscopy Of Geometrically Constrained Systems, Edward Earl Doomes Jan 2002

X-Ray Spectroscopy Of Geometrically Constrained Systems, Edward Earl Doomes

LSU Doctoral Dissertations

Hard X-rays (2 KeV or greater) are used as spectroscopic tools in the characterization of chemical systems. X-ray absorption near edge structure (XANES) spectroscopy is used to characterize multiple groups of chemicals in a systematic fashion. This thesis focuses on chemical systems that in some context have geometrical constraints on their structure. They include self-assembled n-alkanethiol monolayers that are tethered to silver substrates, cyclic sulfides, and (Bis(diphenylphosphino) alkane tetracarbonyl metal complexes. The study of n-alkanethiol monolayers on Ag(111) contains the first observation in the literature of an anomalous resonance in the 18 carbon monolayer. A new interpretation of a subthreshold …


Scientific And Management Perspectives In Wetland Groundwater Hydrology, Lorna Veronica Inniss Jan 2002

Scientific And Management Perspectives In Wetland Groundwater Hydrology, Lorna Veronica Inniss

LSU Doctoral Dissertations

Wetland groundwater hydrology was investigated at different spatial scales to assess the usefulness of the information to coastal managers. Specific objectives were to: (1) review studies related to coastal groundwater discharge, evaluating techniques and identifying controls; (2) understand regional trends in groundwater flow along the U.S. East and Gulf coasts; (3) evaluate the applicability of naturally occurring radioisotopes as indicators of groundwater in a shallow deltaic system; and (4) evaluate groundwater-surface water exchange within Barataria Basin, Louisiana. Results of the review confirmed discharge estimates vary over several orders of magnitude, due to differences in precipitation and tidal prisms. In addition, …