Physical Sciences and Mathematics Commons^™

Synthesis And Radiolabeling Of Potassium Trifluoroborate Benzylidene Anabaseine Derivatives, Aaron Landon Smith

Doctoral Dissertations

Anabaseine has demonstrated a high, non-selective, affinity for the α7- bungarotoxin sensitive neuronal nicotinic acetylcholine receptor binding site found in small cell lung carcinoma. The benzylidene anabaseine derivatives of anabaseine have shown a selective affinity for these binding sites. These studies suggest that radiolabeled benzylidene anabaseine derivatives could act as potential imaging agents to aid in the early detection of lung cancer.

This dissertation outlines the strategy and methods employed in the synthesis of a family of potassium trifluoroborate derivatives of benzylidene anabaseine and their subsequent halogenation. Two of the trifluoroborate salts were converted to their radiolabeled analogues for potential …

Scheduling Tasks With Precedence Constraints On Heterogeneous Distributed Computing Systems, Zhiao Shi

Doctoral Dissertations

Efficient scheduling is essential to exploit the tremendous potential of high performance computing systems. Scheduling tasks with precedence constraints is a well studied problem and a number of heuristics have been proposed.

In this thesis, we first consider the problem of scheduling task graphs in heterogeneous distributed computing systems (HDCS) where the processors have different capabilities. A novel, list scheduling-based algorithm to deal with this particular situation is proposed. The algorithm takes into account the resource scarcity when assigning the task node weights. It incorporates the average communication cost between the scheduling node and its node when computing the Earliest …

Adsorption Of Small Molecules On Mgo And Graphite, Peter Nikolaivich Yaron

Doctoral Dissertations

The physical adsorption of molecules on metal oxide surfaces has direct implications in a number of industrial applications such as; catalysis, electronics, and fuel cells to name a few. Despite the large number of adsorption studies to date, only a small number of systems can be explained with the most advanced ab initio calculations currently available.

One of the simplest metal oxide systems to study is magnesium oxide due to its simple cubic rock-salt structure. Using a patented method, nearly defect-free MgO cubes can be synthesized with a narrow size distribution exposing exclusively the (100) equilibrium crystal face. The use …

Synthesis And Characterization Of Complex Polymer Architectures, Brandon Scott Farmer

Doctoral Dissertations

Anionic polymerization based upon high vacuum technique has been used to synthesize different star polymers using varying linking techniques. In particular chlorosilanes, divinylbenzene, and polyhedral oligomeric silsesquioxane (POSS) chlorosilane derivatives were used in the synthesis of star polymers. These polymers, along with polymers synthesized by others, have been characterized by a range of methods in this work.

A series of polyisoprene (PI) stars were synthesized from dimethylaminopropyllithium (DMAPLi) and subsequently hydrogenated to form poly (ethylene-co-propylene) (PEP) these were characterized by size exclusion chromatography (SEC) coupled with online two angle laser light scattering (TALLS). These polymers were synthesized in an attempt …

Regularization Of The Particle-Particle Interaction In The Nuclear Density Functional Theory, Piotr Jerzy Borycki

Doctoral Dissertations

In this work we show how to regularize the ultraviolet divergences appearing in the local pairing term of the energy density functional. Our approach, entirely rooted in the framework of the Density Functional Theory, is based on the regularization of local densities and currents and can be applied to various classes of energy density functionals. We demonstrated, that for the particular choice of the pairing term of energy density functional, our procedure gives the same regularization scheme to the one obtained earlier by the means of the pairing gap regularization.

We also investigated the non-unitarity of the Bogoliubov tranformation due …

The Effect Of Mobile Phase Composition And Temperature On The Adsorption Behavior Of Tryptophan, Tarab Jamil Ahmad

Doctoral Dissertations

Single-component adsorption isotherm data were acquired by frontal analysis for tryptophan on a C₁₈-Kromasil packed column, using acetonitrile-water solutions of various compositions (2.5, 5, and 7.5% ACN + 1% ACOH). These isotherms have a complex behavior, exhibiting at least one clear inflection point at an intermediate concentration and, possibly, another such point, close to the origin. The isotherm for 2.5 % ACN has the strongest curvature. At high concentrations, all these isotherms tend toward a limit, showing that the adsorbent has a finite saturation capacity. At low concentrations, these isotherms seem to exhibit langmuirian behavior. The isotherm model …

Direct Integration Of Surface Enhanced Raman Spectroscopy As A Detection Mode For Microfluidic Separations And Fluid Handling: Μfluidic-Sers, Raynella Magdalene Connatser

Doctoral Dissertations

The arena of microfluidics (µfluidics) has grown over the past decade to encompass myriad separation techniques and exploit copious detection modes. The direct integration of a vibrational spectroscopic detection technique, rich with structural information, onto a platform that is portable and potentially highly controllable such as µfluidics, could offer redress for some of the problems inherent in many of the electrophoretically driven separations carried out on said devices. Herein, this direct integration is explored, and methods of device fabrication, spectroscopic data collection conditions, analytical figures of merit of the detection technique, and separations method development results are discussed. The creation …

A Measurement Of The Top Quark Mass With A Matrix Element Method, Adam Paul Gibson '96

Doctoral Dissertations

We present a measurement of the mass of the top quark. Our event sample is selected from proton-antiproton collisions, at 1.96 TeV center-of-mass energy, observed with the CDF detector at Fermilab's Tevatron. We consider a 318 pb^-1 dataset collected between March 2002 and August 2004. We select events that contain one energetic lepton, large missing transverse energy, exactly four energetic jets, and at least one displaced vertex b tag. Our analysis uses leading-order tt and background matrix elements along with parameterized parton showering to construct event-by-event likelihoods as a function of top quark mass. From the 63 events observed …

Membrane Systems With Limited Parallelism, Bianca Daniela Popa

Doctoral Dissertations

Membrane computing is an emerging research field that belongs to the more general area of molecular computing, which deals with computational models inspired from bio-molecular processes. Membrane computing aims at defining models, called membrane systems or P systems, which abstract the functioning and structure of the cell. A membrane system consists of a hierarchical arrangement of membranes delimiting regions, which represent various compartments of a cell, and with each region containing bio-chemical elements of various types and having associated evolution rules, which represent bio-chemical processes taking place inside the cell.

This work is a continuation of the investigations aiming to …

Potential Subsurface Structures And Hydrocarbon Reservoirs In The Southern Appalachian Basin Beneath The Cumberland Plateau And Eastern Highland Rim, Tennessee, Kentucky, And Southwestern Virginia, Jonathan Charles Evenick

Doctoral Dissertations

Oil and gas exploration in the southern Appalachian basin is typically concentrated around areas with historically proven reserves and very limited prospecting is conducted elsewhere in the region. To remove possible correlation problems and promote regional prospecting a standardized picking methodology was established in geophysical logs for the Middle Ordovician carbonate lithofacies (Nashville-Stones River Groups). This methodology was then used to correlate the units across Cumberland Plateau of Tennessee, Kentucky, and Virginia, from the Nashville-Jessamine domes to the Clinchport-Whiteoak Mountain thrust in the Valley and Ridge. The same lithofacies may extend in Ohio, Pennsylvania, and New York, suggesting a standardized …

Solute Transport And U(Vi) Reactivity In Natural Heterogeneous Sediments, Melanie A. Mays

Doctoral Dissertations

The primary goal of this research was to determine the relationship between sedimentary geology and solute transport parameters. The overall hypothesis was that the transport of reactive and nonreactive solutes can be predicted using observable sedimentary depositional characteristics. The objective was to test this hypothesis by performing a variety of quantitative transport experiments in intact layered sediment samples. In this study, I used natural materials to explore 1) how mineralogical composition influenced the fate and transport of uranium(VI), 2) the relationship between heterogeneous sedimentary layering and preference for direction of flow, and 3) the mechanisms of solute transport in a …

Growth And Superconductivity Of Pb And Pb-Bi Alloys In The Quantum Regime, Mustafa Murat Ozer

Doctoral Dissertations

Superconductivity is a collective quantum phenomenon that is inevitably suppressed in reduced dimensionality. Questions of how thin superconducting wires or films can be before they lose their superconducting properties have important technological ramifications and go to the heart of understanding formation, coherence, and robustness of the superconducting state in quantum confined geometries. Suppression of superconductivity in low dimensions is usually attributed to thermal or quantum fluctuations, or to pair-breaking Coulomb interactions in the presence of strong disorder. Control and quantification of a film’s disorder length scale remained a critical experimental obstacle, however. Here, we exploit quantum confinement of itinerant electrons …

Asymtre: Building Coalitions For Heterogeneous Multi-Robot Teams, Fang Tang

Doctoral Dissertations

This dissertation addresses the problem of synthesizing task solution strategies for a hetero- geneous robot team to accomplish multi-robot tasks by sharing sensory and computational resources. The approach I developed is called ASyMTRe, which stands for Automated Synthesis of Multi-robot Task solutions through software Reconfiguration, pronounced “Asymmetry”. When dealing with heterogeneous teams, it is challenging to determine how the capabilities of each team member can be appropriately utilized to facilitate the accomplishment of the team-level goal. The ASyMTRe approach provides a way for the robots to reason about how to solve a task depending on their individual capabilities. The fundamental …

Manifestations Of Broken Symmetry: The Surfaces Phases Of Ca2−XSrXRuo4, Robert G. Moore Ii

Doctoral Dissertations

The discovery of superconductivity in Sr₂RuO₄ has renewed vigor in the study of correlated electron systems. The evolution of a p-wave superconducting state from a para- magnetic 2-dimensional Fermi liquid shows the ruthenate superconductivity is anything but conventional. Sr₂RuO₄ is isostructural with La₂CuO₄, the parent compound for the high temperature superconducting family La2_−xSr_xRuO₄. The substitution of Ca²⁺ for Sr²⁺ generates a different structure involving a static rotation and tilt of the RuO₆ octahedral, however, the antiferromagnetic insulating ground state of Ca …

Ab-Initio Calculations Of The Charge-Density Response In Complex Materials, Oscar Dario Restrepo Tovar

Doctoral Dissertations

Our main goal is to have a realistic description of the charge excitations in complex materials in the range of energies such as the coulomb energy U, which is in the eV range. Spectra of these charge excitations, for a large range of wave vector transfers, may provide signatures of the underlying electronic structures. The charge-density response function calculated within Time-dependent Density functional (TDDFT) is an ideal theoretical framework for the calculation of these excitations, since comparison with experimental data (in particular with non-resonant inelastic x-ray scattering experiments) can be done in absolute units (without the need of any adjustable …

Neutron Scat- Tering In The Novel Quantum Magnets: Livo2 And Dmacucl3, Wei Tian

Doctoral Dissertations

The behavior of magnetic systems in the extreme quantum limit is one of the most interesting forefront areas in condensed matter physics. This dissertation investigates two particularly interesting quantum magnets: LiVO₂ and DMACuCl₃. Systematic studies were performed on single crystal samples using different experimental techniques, especially inelastic neutron scattering. Detailed experimental results and corresponding model calculations are presented and discussed in this dissertation.

LiVO₂ is a good candidate to study the interplay between “magnetic frustration” and orbital ordering. V³⁺ ions in LiVO₂ form a triangular lattice involving threefold degenerate t_2g orbitals. LiVO2 undergoes …

Three Population Models Applied To Competition, Disease And Invasion, Erika Asano

Doctoral Dissertations

In this work, we present three diffrent types of population models. The first two models are examined in the context of optimal control problems. The third involves the construction of an invasion model using a significant amount of data.

The first model describes the interaction of three populations, motivated by a combat scenario. One of the three populations can switch the mode of alliance with the other two populations between cooperation and competition. The other two populations always compete with each other. In this system of parabolic partial differential equations, the control is the function which measures the strength of …

Two Biological Applications Of Optimal Control To Hybrid Differential Equations And Elliptic Partial Differential Equations, Wandi Ding

Doctoral Dissertations

In this dissertation, we investigate optimal control of hybrid differential equations and elliptic partial differential equations with two biological applications. We prove the existence of an optimal control for which the objective functional is maximized. The goal is to characterize the optimal control in terms of the solution of the opti- mality system. The optimality system consists of the state equations coupled with the adjoint equations. To obtain the optimality system we differentiate the objective functional with respect to the control. This process is applied to studying two prob- lems: one is a type of hybrid system involving ordinary differential …

Cohomological Dimension With Respect To Nonabelian Groups, Atish Jyoti Mitra

Doctoral Dissertations

This dissertation addresses three aspects of cohomological dimension of metric spaces with respect to nonabelian groups.

In the first part we examine when the Eilenberg-Maclane space (n = 1) of the abelianization of a solvable group being an absolute extensor of a metric space implies the Eilenberg-Maclane space of the group itself is an absolute extensor. We also give an elementary approach to this problem in the case of nilpotent groups and 2-dimensional metric spaces.

The next part of the dissertation is devoted to generalizations of the Cencelj- Dranishnikov theorems relating extension properties of nilpotent CW complexes to its homology …

Adaptive Discontinuous Galerkin Finite Element Methods For Second And Fourth Order Elliptic Partial Differential Equations, Michael A. Saum

Doctoral Dissertations

A unified mathematical and computational framework for implementation of an adaptive discontinuous Galerkin (DG) finite element method (FEM) is developed using the symmetric interior penalty formulation to obtain numerical approximations to solutions of second and fourth order elliptic partial differential equations. The DG-FEM formulation implemented allows for h-adaptivity and has the capability to work with linear, quadratic, cubic, and quartic polynomials on triangular elements in two dimensions. Two different formulations of DG are implemented based on how fluxes are represented on interior edges and comparisons are made. Explicit representations of two a posteriori error estimators, a residual based type and …

Stochastic Propagation Modeling And Early Detection Of Malicious Mobile Code, Xin Xu

Doctoral Dissertations

Epidemic models are commonly used to model the propagation of malicious mobile code like a computer virus or a worm. In this dissertation, we introduce stochastic techniques to describe the propagation behavior of malicious mobile code. We propose a stochastic infection-immunization (INIM) model based on the standard Susceptible-Infected-Removed (SIR) epidemic model, and we get an explicit solution of this model using probability generating function (pgf.). Our experiments simulate the propagation of malicious mobile code with immunization. The simulation results match the theoretical results of the model, which indicates that it is reliable to use INIM model to predict the propagation …

Forest Certification And Nonindustrial Private Forest Landowners: Assessing Awareness, Acceptance, And Educational Preferences, David Chester Mercker

Doctoral Dissertations

In 1977, forest certification originated in West Germany through the Blue Angel Program by authorizing the use of eco-labels for certification of environmental products. Emerging as a tool to attain sustainable forestry, certification provided for a voluntary, market approach to sustainable forest management, rather than traditional regulatory approaches.

Forest certification moved swiftly into the global arena, and by the mid 1990s, it was a topic of intense interest in the United States. The situation for forest certification in the U.S. is somewhat unique because such a large percentage to total forest area is controlled by nonindustrial private forest owners. The …

The Role Of Specific Interactions On The Dispersion And Properties Of Carbon Nanotube-Polymer Nanocomposites, Asif Rasheed

Doctoral Dissertations

This dissertation presents work that exammes the role of specific chemical interactions in enhancing the dispersion of carbon nanotubes in a polymer matrix. Carbon nanotubes (CNT) possess unique mechanical, electrical and thermal properties hence can have a number of potential applications including high strength, light weight composites. Due to strong interaction among nanotubes, they stay as aggregates and hence their full potential for application is severely limited. Utilization of specific chemical interactions to induce/improve miscibility in polymer blends is well known. In this thesis, this approach is applied to carbon nanotubes polymer composites to enhance the dispersion of nanotubes in …

Superdeformation And High Spin Spectroscopy Studies On 174Hf, Martin Krassimirov Djongolov

Doctoral Dissertations

High-spin states of the nucleus ¹⁷⁴Hf were populated using the heavy-ion reactions at the Atlas accelerator facility at the Argonne National Laboratory and the 88" cyclotron facility at the Lawrence Berkeley National Laboratory. The de-exciting [gamma] rays are detected with the GAMMASPHERE spectrometer. In this nucleus, eight superdeformed bands are observed for the first time. Studies on these bands as well as eight bands with normal deformation are performed. The hypothesis for presence of a triaxial shape at high deformation in ¹⁷⁴Hf is tested via lifetime measurements of the states of the superdeformed structures. The deduced quadrupole moments …

Scalable Techniques For Fault Tolerant High Performance Computing, Zizhong Chen

Doctoral Dissertations

As the number of processors in today’s parallel systems continues to grow, the mean-time-to-failure of these systems is becoming significantly shorter than the execu- tion time of many parallel applications. It is increasingly important for large parallel applications to be able to continue to execute in spite of the failure of some components in the system. Today’s long running scientific applications typically tolerate failures by checkpoint/restart in which all process states of an application are saved into stable storage periodically. However, as the number of processors in a system increases, the amount of data that need to be saved into …

Spectroscopic Investigations In Chiral Crystalline And Solution Phases, Andrew Thomas Fischer

Doctoral Dissertations

Chirality is an interesting phenomenon that is not completely understood, and the present work broadens the present body of knowledge using various methods. Crystallization experiments of glycine have confirmed the previously reported phenomenon of nonphotochemical laser induced nucleation (NPLIN), and experiments utilizing a geometry with focused lasers may also display NPLIN, though the results indicate that new factors such as pH of the irradiated solution may affect the crystallizing process. Sodium bromate, NaBrO₃, may also crystallize via NPLIN, though the results are not as conclusive as the glycine experiments. For both glycine and sodium bromate, sound waves produced …

Magnetism And Transport Properties Of Transition Metal Oxides And Nanoparticles, Dane Thomas Gillaspie

Doctoral Dissertations

This dissertation is devoted to the study of the properties of transition metal oxides in both thin film and nanocrystalline forms.

The first section is devoted to the transport properties of manganese oxide thin film samples. The colossal magnetoresistance in these materials is usually explained using double-exchange, but this explanation is only partially correct. Recent theoretical and experimental work has shown that these compounds have a strong tendency towards phase-separation. The impact of strain on phase separation has been investigated by growing films of La_5/8-0.3Pr_0.3Ca_3/8MnO₃ on a variety of substrates. Very small changes …

The Role Of Novel Magnetic Interactions In Surface-Supported Magnetic Nanodot Assemblies, Maria Asuncion Torija Juana

Doctoral Dissertations

The manipulation of matter at the atomic scales facilitates understanding of the fundamental properties of magnetism and opens the possibility of designing systems with novel magnetic properties with limitless industrial applications. This thesis seeks to identify nano-scale magnetic coupling mechanisms in nanostructures assemblies and to better understand different magnetic phases and the associated transitions. This was accomplished through the study of three prototype systems: Fe nanodots of controlled size and density on single crystal substrates of nonmagnetic metals, fractal – dimensional Fe on Cu(111), and FeGe nanowires on Ge(111). The first system shows the presence of a novel magnetic coupling …

Applications Of Modern Statistical Methods To Analysis Of Data In Physical Science, James Eric Wicker

Doctoral Dissertations

Modern methods of statistical and computational analysis offer solutions to dilemmas confronting researchers in physical science. Although the ideas behind modern statistical and computational analysis methods were originally introduced in the 1970’s, most scientists still rely on methods written during the early era of computing. These researchers, who analyze increasingly voluminous and multivariate data sets, need modern analysis methods to extract the best results from their studies.

The first section of this work showcases applications of modern linear regression. Since the 1960’s, many researchers in spectroscopy have used classical stepwise regression techniques to derive molecular constants. However, problems with thresholds …

Iterative Reconstruction Of Cone-Beam Micro-Ct Data, Thomas Matthew Benson

Doctoral Dissertations

The use of x-ray computed tomography (CT) scanners has become widespread in both clinical and preclinical contexts. CT scanners can be used to noninvasively test for anatom- ical anomalies as well as to diagnose and monitor disease progression. However, the data acquired by a CT scanner must be reconstructed prior to use and interpretation. A recon- struction algorithm processes the data and outputs a three dimensional image representing the x-ray attenuation properties of the scanned object. The algorithms in most widespread use today are based on filtered backprojection (FBP) methods. These algorithms are rela- tively fast and work well on …