Physical Sciences and Mathematics Commons^™

Enhancing User Queries In Scientific Visualization With Distribution Information, Christopher Johnson

Doctoral Dissertations

Scientific visualization is concerned with the graphical portrayal of data. Using symbols, color, and natural perceptual cues, humans gain insight into collections of raw numbers that may not be as efficiently processed in non-graphical formats. For simple data, visualization may require only a simple mapping between numeric values and a color scale. But modern scientific, economic, and social data is far from simple. Multiple variables, duration of time, fine resolutions, and wide sampling have yielded data sets of unprecedented complexity. The mapping between such data and its visual appearance is difficult to define. The works described here attempt to make …

Optical Modeling Of Schematic Eyes And The Ophthalmic Applications, Bo Tan

Doctoral Dissertations

The objectives of this dissertation are to advance and broaden the traditional average eye modeling technique by two extensions: 1) population-based and personalized eye modeling for both normal and diseased conditions, and 2) demonstration of applications of this pioneering eye modeling.The first type of representative eye modeling can be established using traditional eye modeling techniques with statistical biometric information of the targeted population. Ocular biometry parameters can be mathematically assigned according to the distribution functions and correlations between parameters. For example, the axial dimension of the eye relates to age, gender, and body height factors. With the investigation results from …

Multiscale Modeling Of The Electronic, Optical, And Magnetic Properties Of Low-Dimensional Metal Systems, Ke Zhao

Doctoral Dissertations

This thesis presents a study of the electronic, optical and magnetic properties of low-dimensional metal systems across multiple scales, using a variety of theoretical techniques including microscopic phenomenological model, ab initio density functional theory (DFT) and classical electromagnetics.

In the study of the interaction between a molecule and metal substrate, a new mechanism of the chemical enhancement for surface-enhanced Raman scattering (SERS) was discovered. Through a microscopic phenomenological model, it has been demonstrated that 102-104 chemical enhancement may originate from the coupling between an electric field parallel to the surface of a metal substrate and the perpendicular vibration mode of …

Search For Electron Antineutrinos From The Sun With Kamland Detector, Oleg Victorovic Perevozchikov

Doctoral Dissertations

In this dissertation I present the results of the search for the electron antineutrinos from the Sun with Kamioka Liquid scintillator Anti-Neutrino Detector (KamLAND). There is no known direct production of the electron antineutrinos in the Sun. However, in the some theoretical models with the large neutrino magnetic moment antineutrinos from the Sun can be produced e.g. via Spin Flavor Precession mechanism (SFP). Search for solar antineutrinos potentially can provide new information about fundamental properties of neutrinos. The most sensitive one-kiloton antineutrino detector KamLAND gives the possibility to search for such antineutrinos.

The analysis described in this dissertation is based …

Assembling The Blue Ridge And Inner Piedmont: Insights Into The Nature And Timing Of Terrane Accretion In The Southern Appalachian Orogen From Geologic Mapping, Stratigraphy, Kinematic Analysis, Petrology, Geochemistry, And Modern Geochronology, Arthur James Merschat

Doctoral Dissertations

Detailed geologic mapping, SHRIMP U-Pb zircon geochronology, geochemistry, petrology, and structural and kinematic analyses were applied to decipher the structure, tectonic heredity, and Paleozoic accretionary history of suspect terranes of the southern Appalachian Blue Ridge (BR) and Inner Piedmont (IP). Detailed geologic mapping in the Waynesville and Sam Knob 7.5-minute quadrangles recognized the Great Balsam Mountains window cored by sillimanite I and II zone Dahlonega gold belt rocks, overthrust by migmatitic biotite gneiss of the Cartoogechaye terrane to the northwest, and migmatitic Tallulah Falls Formation of the Tugaloo terrane to the southeast. Suspect terranes of the BR and IP consist …

Adaptive Discontinuous Galerkin Finite Element Methods, Haihang You

Doctoral Dissertations

The Discontinuous Galerkin Method is one variant of the Finite Element Methods for solving partial differential equations, which was first introduced by Reed and Hill in 1970’s [27]. Discontinuous GalerkinMethod (DGFEM) differs from the standard Galerkin FEMthat continuity constraints are not imposed on the inter-element boundaries. It results in a solution which is composed of totally piecewise discontinuous functions. The absence of continuity constraints on the inter-element boundaries implies that DG method has a great deal of flexibility at the cost of increasing the number of degrees of freedom. This flexibility is the source of many but not all of …

Studies On A Polarized Proton Target For Reactions With Radioactive Ion Beams, Juan Pablo Urrego-Blanco

Doctoral Dissertations

Over the last few years, much progress has been made towards the understanding of basic properties of nuclei with extreme neutron to proton ratios. However, the study of phenomena involving spin polarized nuclei near the drip lines remains practically unexplored. The importance of such studies lies in the fact that the most complete knowledge of the scattering matrix is obtained in reactions with polarized particles. The purpose of this dissertation was to explore the feasibility of using polarized probes in reactions with exotic nuclei. We identified areas where reactions between Radioactive Ion Beams (RIBs) and light polarized targets open a …

Experimental Studies Of Exotic Negative Ions, Shaun Gerald Ard

Doctoral Dissertations

Although negative ions have been studied extensively for quite some time, their study continues to offer insight into developing and refining quantum chemical modeling techniques. Negative ion states remain difficult to treat ab initio due to the significant electron-electron correlation, thus putting a premium on experimental results to guide the way. Experimental techniques such as Electrospray Ionization (ESI) and Rydberg Electron Transfer (RET) have made study of some exotic negative ions in the gas phase possible for the first time. Multiply Charged Anions (MCAs) of several families of molecules were studied using Collision Induced Dissociation (CID) and Infrared Multi Photon …

Single Walled Carbon Nanotube Networks As Transparent Conductors, Matthew Patrick Garrett

Doctoral Dissertations

A variety of technological applications depend on transparent conducting films, and carbon nanotubes have the properties required to serve in that role. Single-walled carbon nanotube networks have been studied as transparent conductors in order to understand and optimize their electrical and optical properties. Nanotube films are complex networks of semiconducting and metallic nanotubes, bundled and branched in multifarious directions, with different strength connections between bundles. Chemical modification of nanotubes and inclusion of non-nanotube material can further alter network properties. Separating the contributions of all aspects of the network is a necessary but daunting task in order to optimize nanotube films. …

Spectroscopic Imaging For The Detection And Identification Of Bacterial Contaminations, Michael Gilbert

Doctoral Dissertations

There exist many types of harmful bacteria that can contaminate foods and cause serious illness, which often have their own best courses of treatment. This requires the classification of different types of bacteria. Traditional methods of bacterial identification, while able to provide accurate classification, are often very time-consuming processes. In the case of a potentially fatal bacterial infection, time is often of the essence. FTIR spectroscopy is a faster, more practical alternative that can discriminate different strains of bacteria, based on their spectral signatures, with high confidence.

Bacterial contaminations on food exist as small, localized colonies that must be found …

Countable Groups As Fundamental Groups Of Compacta In Four-Dimensional Euclidean Space, Ziga Virk

Doctoral Dissertations

This dissertation addresses the question of realization of countable groups as funda- mental groups of continuum. In first chapter we discuss classical realizations in the category of CW complexes. We introduce Eilenberg-Maclane spaces and their topological properties. The second chapter provides recent developments on realization question such as those of Shelah, Keesling, ... The third chapter proves the realization theorem for countable groups. The re- sulting space is compact path connected, connected subspace of four dimensional Euclidean space.

Optimal Control Applied To Population And Disease Models, Rachael Lynn Miller Neilan

Doctoral Dissertations

This dissertation considers the use of optimal control theory in population models for the purpose of characterizing strategies of control which minimize an invasive or infected population with the least cost. Three different models and optimal control problems are presented. Each model describes population dynamics via a system of differential equations and includes the effects of one or more control methods.

The first model is a system of two ordinary differential equations describing dynamics between a native population and an invasive population. Population growth terms are functions of the control, constructed so that the value of the control may affect …

Small And Large Scale Limits Of Multifractal Stochastic Processes With Applications, Jennifer Laurie Sinclair

Doctoral Dissertations

Various classes of multifractal processes, that is processes that display different properties at different scales, are studied. Most of the processes examined in this work exhibit stable trends at small scales and Gaussian trends at large scales, although the opposite can also occur. Many natural phenomena exhibit a fractal structure depending on some scaling factor, such as space or time. Thus, these types of processes have many useful modeling applications, including Biology and Economics. First, generalized tempered stable processes are defined and studied, following the original work on tempered stable processes by Jan Rosinski [16]. Generalized tempered stable processes encompass …

Two-Step Variations For Processes Driven By Fractional Brownian Motion With Application In Testing For Jumps From The High Frequency Data, Shiying Si

Doctoral Dissertations

In this dissertation we introduce the realized two-step variation of stochastic processes and develop its asymptotic theory for processes based on fractional Brownian motion and on more general Gaussian processes with stationary increments. The realized two-step variation is analogous to the realized 1, 1-order bipower variation introduced by Barndorff-Nielsen and Shephard [8] but mathematically is simpler to deal with. The powerful techniques of Wiener/Itˆo/Malliavin calculus for establishing limit laws play a key rule in our proofs. We include some stochastic simulations as an illustration of our theory. As a result of our study, we provide test statistics for testing for …

Novel Approach To Ocular Photoscreening, Kevin Charles Baker

Doctoral Dissertations

Photoscreening is a technique that is typically applied in mass pediatric vision screening due to advantage of its objective, binocular, and cost-effective nature. Through the retinal reflex image, ocular alignment and refractive status are evaluated. In the USA, this method has screened millions of preschool children in the past years. Nevertheless, the efficiency of the screening has been contentious. In this dissertation, the technique is reviewed and reexamined. Revisions of photoscreening technique are developed to detect and quantify strabismus, refractive errors, and high-order ocular aberrations. These new optical designs overcome traditional design deficiencies in three areas:

First, a Dynamic Hirschberg …

A Theoretical Study Of Methanol Oxidation Mechanisms By Methanol Dehydrogenase Enzymes For Fuel Cell Applications, Nagesh B. Idupulapati

Doctoral Dissertations

Enzymes are considered for electrochemical generation of power in fuel cells. Methanol dehydrogenase (MDH) is one such enzyme, which has been used as an anodic catalyst for a methanol-fed biofuel cell producing enough power for small electronic device applications. In practice, however, there are power output limitations associated with this MDH fuel cell, which may potentially be eliminated or reduced if the reactivity of this enzyme during the oxidation of methanol at the molecular level is clearly understood.

Two mechanisms for the methanol oxidation process by MDH have been proposed in the literature, Addition-Elimination (A-E) and Hydride Transfer (H-T), but …

Computational Study Of Pristine And Titanium-Doped Sodium Alanates For Hydrogen Storage Applications, Gopi Krishna Phani Dathar

Doctoral Dissertations

The emphasis of this research is to study and elucidate the underlying mechanisms of reversible hydrogen storage in pristine and Ti-doped sodium aluminum hydrides using molecular modeling techniques. An early breakthrough in using complex metal hydrides as hydrogen storage materials is from the research on sodium alanates by Bogdanovic et al., in 1997 reporting reversible hydrogen storage is possible at moderate temperatures and pressures in transition metal doped sodium alanates. Anton reported titanium salts as the best catalysts compared to all other transition metal salts from his further research on transition metal doped sodium alanates. However, a few questions remained …

Text Summarization Using Concept Hierarchy, Xiaomei Huang

Doctoral Dissertations

This dissertation aims to create new sentences to summarize text documents. In addition to generating new sentences, this project also generates new concepts and extracts key sentences to summarize documents. This project is the first research work that can generate new key concepts and can create new sentences to summarize documents.

Automatic document summarization is the process of creating a condensed version of the document. The condensed version extracts the key contents from the original document. Most related research uses statistical methods that generate a summary based on word distribution in the document. In this dissertation, we create a summary …

Computational Simulation Of Strain Localization: From Theory To Implementation, Shouxin Wu

Doctoral Dissertations

Strain localization in the form of shear bands or slip surfaces has widely been observed in most engineering materials, such as metals, concrete, rocks, and soils. Concurrent with the appearance of localized deformation is the loss of overall load-carrying capacity of the material body. Because the deformation localization is an important precursor of material failure, computational modeling of the onset and growth of the localization is indispensable for the understanding of the complete mechanical response and post-peak behavior of materials and structures. Simulation results can also be used to judge the failure mechanisms of materials and structures so that the …

Chasing Μ, Joseph P. Cannon

Doctoral Dissertations

Conducting and semiconducting, π-conjugated polymers are promising materials for micro- and nano-optoelectronic applications because of their widely tunable physical, electrical, and optical properties. These polymers have been used to fabricate a number of electronic devices including field-effect transistors, light-emitting diodes, and photovoltaic cells. However, widespread commercial application of these devices has yet to be realized, due in part to poor electronic transport characteristics and device degradation.

Nanostructuring of conjugated polymers by various methods has demonstrated marked improvements in molecular ordering and electronic transport. In this research, nanoscale, tubular structures of semiconducting polymers fabricated by template wetting nanofabrication procedures are explored. …

Discrete Nondeterministic Modeling Of Biochemical Networks, John R. Jack

Doctoral Dissertations

The ideas expressed in this work pertain to biochemical modeling. We explore our technique, the Nondeterministic Waiting Time algorithm, for modeling molecular signaling cascades. The algorithm is presented with pseudocode along with an explanation of its implementation. The entire source code can be found in the Appendices. This algorithm builds on earlier work from the lab of Dr. Andrei Nun, the advisor for this dissertation. We discuss several important extensions including: (i) a heap with special maintenance functions for sorting reaction waiting times, (ii) a nondeterministic component for handling reaction competition, and (iii) a memory enhancement allowing slower reactions to …

Crustal Modification By Tectonic Events And Upper Mantle Anisotropy Beneath The Midcontinent Rift And New Madrid Seismic Zone: Insights From Receiver Function Studies And Teleseismic Shear Wave Splitting, Moikwathai Moidaki

Doctoral Dissertations

"The earth's crust and upper mantle have been continually modified by tectonic processes such as rifting, earthquake activity. In this dissertation, shear wave splitting and receiver function techniques were employed to study the extent of crustal and upper mantle modifications beneath the New Madrid Seismic Zone (NMSZ) and the Midcontinent Rift (MCR). Shear wave splitting analysis in the MCR reveals the presence of fossilised anisotropy along the rift axis...In the NMSZ, anticipated rift-parallel fast directions associated with vertical magmatic dikes or along-rift flow, rift-orthogonal fast directions from small-scale convection, or reduction in splitting times as a result of vertical asthenospheric …

Interference Effects Due To Projective-Target Nucleus Scattering In Single Ionization Of Molecular Hydrogen By 75 Kev Proton Impact, Jason S. Alexander

Doctoral Dissertations

"Doubly-differential cross-sections for the single ionization of molecular hydrogen by 75 keV proton impact have been measured as a function of the projectile scattering angle and energy loss and compared to available theoretical models. Interference structures are directly observed in the scattering angular dependence of the DDCS. The phase angle appears to be most sensitive to the projectile angle but not as sensitive to the electron energy, suggesting that the projectile - target nucleus interaction plays a central role in the interference. The large-angle structures disappear at electron speeds near the projectile speed. This may be due to a focusing …

Fully Differential Cross Sections For Four-Body Scattering Processes, Allison L. Harris

Doctoral Dissertations

"While the original concept of the atom can be traced back to the ancient Greeks, current knowledge of the atom is due largely to the study of atomic collisions. The structure of atoms is now fairly well understood, but the understanding of their interactions remains incomplete. In atomic collisions, the particles involved in the collision interact through the Coulomb force, which is known exactly. However, for Coulomb forces, the solution of the Schrödinger equation can only be obtained analytically for two mutually interacting particles. As a result, when more than two particles are involved, theory must resort to approximations. The …

The Cretaceous-Paleogene Transition In The Northern Mississippi Embayment, S.E. Missouri: Palynology, Micropaleontology, And Evidence Of A Mega-Tsunami Deposit, Tambra L. Eifert

Doctoral Dissertations

"Upper Cretaceous to lower Paleogene sedimentary rocks in Southeastern Missouri record the northwest extension of the Mississippi Embayment, yet very little information exists about them due to lack of exposures. Access to borehole and trench material and well logs provided an opportunity to study the sedimentology, palynology and micropaleontology of the three formations spanning the Cretaceous-Paleogene (K-Pg) boundary interval: Owl Creek (Cretaceous) and Clayton and Porters Creek (Paleocene). Lithologic features, palynomorphs (mainly spores, pollen, dinoflagellate cysts), dispersed organic matter, and foraminifera were used to interpret biostratigraphy, paleovegetation, paleoclimatic and depositional conditions, thereby creating a framework upon which further questions involving …

Holomorphic Extensions In Toric Varieties, Malgorzata Aneta Marciniak

Doctoral Dissertations

"The dissertation describes the Hartogs and the Hartogs-Bochner extension phenomena in smooth toric varieties and their connection with the first cohomology group with compact support and sheaf coefficients. The affirmative and negative results are proved for toric surfaces and for line bundles over toric varieties using topological, analytic, and algebraic methods"--Abstract, page iii.

A Study Of The Beneficial Role Of Thiol Antioxidant Supplementation In Various Forms Of Glutathione Deficiency, Linu Sara Abraham

Doctoral Dissertations

"Oxidative stress plays a major role in the pathology of numerous disorders afflicting humans, ranging from neurodegenerative diseases, to cancer, and heavy metal toxicity. Scientists are on the constant lookout for new and better antioxidants that have the ability to slow, if not stop the harmful degenerative effects of free radicals in oxidative stress related disorders. Both synthetic and naturally occurring compounds are being constantly screened for their antioxidant properties. This study attempted to evaluate the abilities of a thiol antioxidant, N-Acetylcysteine amide (NACA), to protect cells from the harmful effects of glutathione depletion in two different models of oxidative …

Investigating The Impact Of Microbial Interactions With Geologic Media On Geophysical Properties, Caroline A. Davis

Doctoral Dissertations

"The goals of this study were to investigate the effect of: (1) microbial metabolic byproducts, microbial growth, and biofilm formation on the low frequency electrical properties of porous media, (2) biofilm formation on acoustic wave properties, and (3) the natural electrical (self-potential) signatures associated with an in-situ biological permeable reactive barrier (PRB). The results suggest: (1) increases in electrolytic conductivity are consistent with increased concentrations of organic acids and biosurfactants; (2) mineral weathering promoted by organic acids causes increases in electrolytic conductivity, concomitant with increases in major cation concentrations; (3) interfacial conductivity generally parallels microbial cell concentrations and biofilm formation; …

Investigation Of The Interactions Between Selected Nanoparticles And Human Lung Carcinoma Cells At The Single Cell And Single Particle Level, Isaac Stayton

Doctoral Dissertations

"The recent advances in nanomaterials development and applications have sparked concerns regarding the safety of these materials in living organisms. This body of work investigates specific interactions between chosen nanoparticles and living human lung carcinoma (A549) cells"--Abstract, page iv.

Electrodeposition Of Inorganic Materials With Tailored Shapes And Chiral Morphologies, Elizabeth A. Kulp

Doctoral Dissertations

"This dissertation investigates the electrodeposition of metal oxide films and biomaterial deposits on polycrystalline and single crystal substrates. Paper I describes the mechanisms and the characterization of an electrodeposited polycrystalline insulator, ceria (CeO₂), on Hastelloy substrates produced by the electrochemical oxidation of Ce(III) acetate complexes. In Paper II, epitaxial films of magnetite (Fe₃O₄) and ferrihydrite (Fe₁₀O₁₄(OH)₂) are deposited on gold single crystals. Paper III reports the electrodeposition of epitaxial Fe₃O₄ and zinc ferrite (ZnFe₂O₄) periodic nanostructures known as superlattices by pulsing between two potentials. Papers IV and V describe chiral electrodeposition. In Paper IV, epitaxial, chiral orientations of cupric oxide …