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A Measurement of the Lifetime of the Lambda_b Baryon with the CDF Detector at the Tevatron Run II

Description: In March 2001 the Tevatron accelerator entered its Run II phase, providing colliding proton and anti-proton beams with an unprecedented center-of-mass energy of 1.96 TeV. The Tevatron is currently the only accelerator to produce {Lambda}{sub b} baryons, which provides a unique opportunity to measure the properties of these particles. This thesis presents a measurement of the mean lifetime of the {Lambda}{sub b} baryon in the semileptonic channel {Lambda}{sub b}{sup 0} {yields} {Lambda}{sub c}{s… more
Date: December 1, 2004
Creator: Unverhau, Tatjana Alberta Hanna & U., /Glasgow
Partner: UNT Libraries Government Documents Department
open access

Search for Gauge Mediated Supersymmetry in the gamma gamma missing ET Channel

Description: We present results on a search for Gauge Mediated Supersymmetry in the di-photon final state using Run II data collected by the D0 Experiment at the Fermilab Tevatron Collider. We discuss event selection, Standard Model backgrounds, and the lower limits on the lightest neutralino and chargino masses resulted from this analysis.
Date: December 1, 2004
Creator: Kesisoglou, Stilianos Isaak & U., /Brown
Partner: UNT Libraries Government Documents Department
open access

A Measurement of the production cross section of top-antitop pairs in proton-antiproton collisions at a center of mass of 1.96 TeV using secondary vertex b-tagging.

Description: A measurement of the t{bar t} pair production cross section is presented using 162 pb{sup -1} of data collected by the CDF experiment during Run II at the Tevatron. t{bar t} events in the lepton+jets channel are isolated by identifying electrons and muons, reconstructing jets and transverse missing energy, and identifying b jets with a secondary vertex tagging algorithm. The efficiency of the algorithm is measured in a control sample using a novel technique that is less dependent on the simulat… more
Date: December 1, 2004
Creator: Bachacou, Henri
Partner: UNT Libraries Government Documents Department
open access

A Measurement of the Mass of the Top Quark in Lepton + Jets Events at CDF

Description: This document presents a measurement of the top quark mass using the CDF run II detector at Fermilab. Colliding beams of protons and anti-protons at Fermilab's Tevatron ({radical}s = 1.96 TeV) produce top/anti-top pairs, which decay to W{sup +}W{sup -} b{bar b}; events are selected where one W decays hadronically, and one W decays to either e or {mu} plus a neutrino. The data sample was collected between March 2002 and September 2003, and corresponds to an integrated luminosity of approximately… more
Date: December 1, 2004
Creator: Brubaker, Erik Matthews
Partner: UNT Libraries Government Documents Department
open access

Solvation!

Description: This dissertation consists of two closely related parts: theory development and coding of correlation effects in a model potential for solvation, and study of solvent effects on chemical reactions and processes. The effective fragment potential (EFP) method has been re-parameterized, using density functional theory (DFT), more specifically, the B3LYP functional. The DFT based EFP method includes short-range correlation effects; hence it is a first step in incorporating the treatment of correlat… more
Date: December 19, 2004
Creator: Adamovic, Ivana
Partner: UNT Libraries Government Documents Department
open access

Oxidation Behavior and Chlorination Treatment to Improve Oxidation Resistance of Nb-Mo-Si-B Alloys

Description: This thesis is written in an alternate format. The thesis is composed of a general introduction, two original manuscripts, and a general conclusion. References cited within each chapter are given at the end of each chapter. The general introduction starts with the driving force behind this research, and gives an overview of previous work on boron doped molybdenum silicides, Nb/Nb{sub 5}Si{sub 3} composites, boron modified niobium silicides and molybdenum niobium silicides. Chapter 2 focuses on … more
Date: December 19, 2004
Creator: Behrani, Vikas
Partner: UNT Libraries Government Documents Department
open access

New Palladium-Catalyzed Approaches to Heterocycles and Carbocycles

Description: The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I{sub 2}, ICl, PhSeCl, PhSCl and p-O{sub 2}NC{sub 6}H{sub 4}SCl to give the corresponding halogen-, selenium- and sulfur-containing disubstituted isoquinolines and naphthyridines, respectively. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. This meth… more
Date: December 19, 2004
Creator: Huang, Qinhua
Partner: UNT Libraries Government Documents Department
open access

Group 4 Metalloporphyrin diolato Complexes and Catalytic Application of Metalloporphyrins and Related Transition Metal Complexes

Description: In this work, the first examples of group 4 metalloporphyrin 1,2-diolato complexes were synthesized through a number of strategies. In general, treatment of imido metalloporphyrin complexes, (TTP)M=NR, (M = Ti, Zr, Hf), with vicinal diols led to the formation of a series of diolato complexes. Alternatively, the chelating pinacolate complexes could be prepared by metathesis of (TTP)MCl{sub 2} (M = Ti, Hf) with disodium pinacolate. These complexes were found to undergo C-C cleavage reactions to p… more
Date: December 19, 2004
Creator: Du, Guodong
Partner: UNT Libraries Government Documents Department
open access

Hole Burning Imaging Studies of Cancerous and Analogous Normal Ovarian Tissues Utilizing Organelle Specific Dyes

Description: Presented in this dissertation is the successful demonstration that nonphotochemical hole burning (NPWB) imaging can be used to study in vitro tissue cellular systems for discerning differences in cellular ultrastructures due to cancer development. This has been accomplished with the surgically removed cancerous ovarian and analogous normal peritoneal tissues from the same patient and the application of a fluorescent mitochondrion specific dye, Molecular Probe MitoFluor Far Red 680 (MF680), com… more
Date: December 19, 2004
Creator: Matsuzaki, Satoshi
Partner: UNT Libraries Government Documents Department
open access

Nuclear reactions with 11C and 14O radioactive ion beams

Description: Radioactive ion beams (RIBs) have been shown to be a useful tool for studying proton-rich nuclides near and beyond the proton dripline and for evaluating nuclear models. To take full advantage of RIBs, Elastic Resonance Scattering in Inverse Kinematics with Thick Targets (ERSIKTT), has proven to be a reliable experimental tool for investigations of proton unbound nuclei. Following several years of effort, Berkeley Experiments with Accelerated Radioactive Species (BEARS), a RIBs capability, has … more
Date: December 9, 2004
Creator: Guo, Fanqing
Partner: UNT Libraries Government Documents Department
open access

GaAs Blocked-Impurity-Band Detectors for Far-Infrared Astronomy

Description: High-purity and doped GaAs films have been grown by Liquid-phase epitaxy (LPE) for development of a blocked impurity band (BIB) detector for far-infrared radiation. The film growth process developed has resulted in the capability to grow GaAs with a net active impurity concentration below 1 x 10{sup 13} cm{sup -3}, ideal for the blocking layer of the BIB detector. The growth of n-type LPE GaAs films with donor concentrations below the metal-insulator transition, as required for the absorbing la… more
Date: December 21, 2004
Creator: Cardozo, Benjamin Lewin
Partner: UNT Libraries Government Documents Department
open access

Solidification at the High and Low Rate Extreme

Description: The microstructures formed upon solidification are strongly influenced by the imposed growth rates on an alloy system. Depending on the characteristics of the solidification process, a wide range of growth rates is accessible. The prevailing solidification mechanisms, and thus the final microstructure of the alloy, are governed by these imposed growth rates. At the high rate extreme, for instance, one can have access to novel microstructures that are unattainable at low growth rates. While the … more
Date: December 19, 2004
Creator: Meco, Halim
Partner: UNT Libraries Government Documents Department
open access

Fabrication of Ceramic Layer-by-Layer Infrared Wavelength Photonic Band Gap Crystals

Description: Photonic band gap (PBG) crystals, also known as photonic crystals, are periodic dielectric structures which form a photonic band gap that prohibit the propagation of electromagnetic (EM) waves of certain frequencies at any incident angles. Photonic crystals have several potential applications including zero-threshold semiconductor lasers, the inhibition of spontaneous emission, dielectric mirrors, and wavelength filters. If defect states are introduced in the crystals, light can be guided from … more
Date: December 19, 2004
Creator: Kang, Henry Hao-Chuan
Partner: UNT Libraries Government Documents Department
open access

Benchmarking: More Aspects of High Performance Computing

Description: The original HPL algorithm makes the assumption that all data can be fit entirely in the main memory. This assumption will obviously give a good performance due to the absence of disk I/O. However, not all applications can fit their entire data in memory. These applications which require a fair amount of I/O to move data to and from main memory and secondary storage, are more indicative of usage of an Massively Parallel Processor (MPP) System. Given this scenario a well designed I/O architectur… more
Date: December 19, 2004
Creator: Ravindrudu, Rahul
Partner: UNT Libraries Government Documents Department
open access

Coupling Temperature Control with Electrochemically Modulated Liquid Chromatography: Fundamental Aspects and Applications

Description: The primary focus of the doctoral research presented herein has been the integration of temperature control into electrochemically modulated liquid chromatography (EMLC). The combination of temperature control and the tunable characteristics of carbonaceous EMLC stationary phases have been invaluable in deciphering the subtleties of the retention mechanism. The effects of temperature and E{sub app} on the retention of several naphthalene disulfonates were therefore examined by the van' Hoff rel… more
Date: December 19, 2004
Creator: Ponton, Lisa M.
Partner: UNT Libraries Government Documents Department
open access

Morphological Control of Multifunctional Mesoporous Silica Nanomaterials for Catalysis Applications

Description: I found an efficient method to control the morphology of the organically monofunctionalized mesoporous silica materials by introducing different types of organoalkoxysilanes in a base-catalyzed co-condensation reaction. The monofunctionalized materials exhibit different particle morphologies relative to the pure MCM-41 material. The concentration dependence of the morphology is a critical factor to determine the final particle shape. A proposed mechanism of the shape evolution is also offered. … more
Date: December 19, 2004
Creator: Huh, Seong
Partner: UNT Libraries Government Documents Department
open access

Development of Chiral LC-MS Methods for small Molecules and Their Applications in the Analysis of Enantiomeric Composition and Pharmacokinetic Studies

Description: The purpose of this research was to develop sensitive LC-MS methods for enantiomeric separation and detection, and then apply these methods for determination of enantiomeric composition and for the study of pharmacokinetic and pharmacodynamic properties of a chiral nutraceutical. Our first study, evaluated the use of reverse phase and polar organic mode for chiral LC-API/MS method development. Reverse phase methods containing high water were found to decrease ionization efficiency in electrospr… more
Date: December 19, 2004
Creator: Desai, Meera Jay
Partner: UNT Libraries Government Documents Department
open access

Microstructural Development in Al-Si Powder During Rapid Solidification

Description: Powder metallurgy has become an increasingly important form of metal processing because of its ability to produce materials with superior mechanical properties. These properties are due in part to the unique and often desirable microstructures which arise as a result of the extreme levels of undercooling achieved, especially in the finest size powder, and the subsequent rapid solidification which occurs. A better understanding of the fundamental processes of nucleation and growth is required to… more
Date: December 19, 2004
Creator: Genau, Amber Lynn
Partner: UNT Libraries Government Documents Department
open access

Critical Behavior of Thermal Expansion and Magnetostriction in the Vicinity of the First order transition at the Curie Point of Gd5(SixGe1-x)4

Description: Thermal expansion (TE) and magnetostriction (MS) measurements have been conducted for Gd{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} with a series of x values to study its critical behavior in the vicinity of transition temperatures. It was found that the Curie temperature of Gd{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} for x 0 {approx} 0.5 is dependent on magnetic field, direction of change of temperature (Tc on cooling was lower than Tc on heating), purity of Gd starting material, compositions, material pr… more
Date: December 19, 2004
Creator: Han, Mangui
Partner: UNT Libraries Government Documents Department
open access

Catalyzed hydrogenation of nitrogen and ethylene on metal (Fe, Pt) single crystal surfaces and effects of coadsorption: A sum frequency generation vibrational spectroscopy study

Description: High-pressure catalytic reactions and associated processes, such as adsorption have been studied on a molecular level on single crystal surfaces. Sum Frequency Generation (SFG) vibrational spectroscopy together with Auger Electron Spectroscopy (AES), Temperature Programmed Desorption (TPD) and Gas Chromatography (GC) were used to investigate the nature of species on catalytic surfaces and to measure the catalytic reaction rates. Special attention has been directed at studying high-pressure reac… more
Date: December 15, 2004
Creator: Westerberg, Staffan Per Gustav
Partner: UNT Libraries Government Documents Department
open access

Ultrasonic Concentration in a Line-Driven Cylindrical Tube

Description: The fractionation of particles from their suspending fluid or noninvasive micromanipulation of particles in suspension has many applications ranging from the recovery of valuable reagents from process flows to the fabrication of microelectromechanical devices. Techniques based on size, density, solubility, or electromagnetic properties exist for fulfilling these needs, but many particles have traits that preclude their use such as small size, neutral buoyancy, or uniform electromagnetic charact… more
Date: December 15, 2004
Creator: Goddard, G.R.
Partner: UNT Libraries Government Documents Department
open access

Performance Study and Dynamic Optimization Design for Thread Pool Systems

Description: Thread pools have been widely used by many multithreaded applications. However, the determination of the pool size according to the application behavior still remains problematic. To automate this process, in this thesis we have developed a set of performance metrics for quantitatively analyzing thread pool performance. For our experiments, we built a thread pool system which provides a general framework for thread pool research. Based on this simulation environment, we studied the performance … more
Date: December 19, 2004
Creator: Xu, Dongping
Partner: UNT Libraries Government Documents Department
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Quantum Chemistry, and Eclectic Mix: From Silicon Carbide to Size Consistency

Description: Chemistry is a field of great breadth and variety. It is this diversity that makes for both an interesting and challenging field. My interests have spanned three major areas of theoretical chemistry: applications, method development, and method evaluation. The topics presented in this thesis are as follows: (1) a multi-reference study of the geometries and relative energies of four atom silicon carbide clusters in the gas phase; (2) the reaction of acetylene on the Si(100)-(2x1) surface; (3) an… more
Date: December 19, 2004
Creator: Rintelman, Jamie Marie
Partner: UNT Libraries Government Documents Department
open access

Gas Sensors Based on Ceramic p-n Heterocontacts

Description: Ceramic p-n heterocontacts based on CuO/ZnO were successfully synthesized and a systematic study of their hydrogen sensitivity was conducted. The sensitivity and response rates of CuO/ZnO sensors were studied utilizing current-voltage, current-time, and impedance spectroscopy measurements. The heterocontacts showed well-defined rectifying characteristics and were observed to detect hydrogen via both dc and ac measurements. Surface coverage data were derived from current-time measurements which … more
Date: December 19, 2004
Creator: Aygun, Seymen Murat
Partner: UNT Libraries Government Documents Department
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