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Study of the Ds+ to K+K-e+ nu Decay Channel with the BaBar Experiment

Description: Charm semileptonic decays allow a validation of lattice QCD calculations through the measurement of the hadronic form factors, which characterize the effect of strong interaction in these reactions. The accuracy of such calculations is crucial for the improvement of the test of the standard model in flavor physics. This thesis presents a study of the D{sub s}{sup +} {yields} K{sup +}K{sup -}e{sup +}{nu}{sub e} channel using 214 fb{sup -1} recorded by de BAbar experiment. For events with a K{sup… more
Date: September 9, 2008
Creator: Serrano, Justine & /Orsay, IPN /SLAC
Partner: UNT Libraries Government Documents Department
open access

Experimental Study of the Spin Structure of the Neutron (3He) at low Q2: a connection between the Bjorken and Gerasimov-Drell-Hearn Sum Rules

Description: The authors have presented the motivations in gathering doubly polarized data in the quasi-elastic, resonance and DIS domains. These data were used to calculate the extended GDH integral. The comparison of this quantity with the spin dependent forward Compton amplitude {bar S}{sub 1} is of particular importance for the unification of the two strong interaction descriptions (nucleonic/hadronic vs. partonic) because {bar S}{sub 1} is the first quantity theoretically calculable in the full Q{sup 2… more
Date: October 9, 2000
Creator: Deur, Alexander
Partner: UNT Libraries Government Documents Department
open access

Indium Growth and Island Height Control on Si Submonolayer Phases

Description: Nanotechnology refers any technique that involves about object with nanoscale (10{sup -9} m) or even smaller. It has become more and more important in recently years and has changed our world dramatically. Most of modern electronic devices today should thanks to the miniaturizing driven by development of nanotechnology. Recent years, more and more governments are investing huge amount of money in research related to nanotechnology. There are two major reasons that nanostructure is so fascinate.… more
Date: May 9, 2009
Creator: Chen, Jizhou
Partner: UNT Libraries Government Documents Department
open access

Band anticrossing effects in highly mismatched semiconductor alloys

Description: The first five chapters of this thesis focus on studies of band anticrossing (BAC) effects in highly electronegativity- mismatched semiconductor alloys. The concept of bandgap bowing has been used to describe the deviation of the alloy bandgap from a linear interpolation. Bowing parameters as large as 2.5 eV (for ZnSTe) and close to zero (for AlGaAs and ZnSSe) have been observed experimentally. Recent advances in thin film deposition techniques have allowed the growth of semiconductor alloys co… more
Date: September 9, 2002
Creator: Wu, Junqiao
Partner: UNT Libraries Government Documents Department
open access

Resorption Rate Tunable Bioceramic: Si, Zn-Modified Tricalcium Phosphate

Description: This dissertation is organized in an alternate format. Several manuscripts which have already been published or are to be submitted for publication have been included as separate chapters. Chapter 1 is a general introduction which describes the dissertation organization and introduces the human bone and ceramic materials as bone substitute. Chapter 2 is the background and literature review on dissolution behavior of calcium phosphate, and discussion of motivation for this research. Chapter 3 is… more
Date: August 9, 2006
Creator: Wei, Xiang
Partner: UNT Libraries Government Documents Department
open access

Couples Magnetic and Structural Transitions in High-Purity Dy and Gd5SbxGe4-x

Description: Magnetic materials exhibiting magnetic phase transitions simultaneously with structural rearrangements of their crystal lattices hold a promise for numerous applications including magnetic refrigeration, magnetomechanical devices and sensors. We undertook a detailed study of a single crystal of dysprosium metal, which is a classical example of a system where magnetic and crystallographic sublattices can be either coupled or decoupled from one another. Magnetocaloric effect, magnetization, ac ma… more
Date: August 9, 2006
Creator: Chernyshov, Alexander S.
Partner: UNT Libraries Government Documents Department
open access

Automated High Throughput Protein Crystallization Screening at Nanoliter Scale and Protein Structural Study on Lactate Dehydrogenase

Description: The purposes of our research were: (1) To develop an economical, easy to use, automated, high throughput system for large scale protein crystallization screening. (2) To develop a new protein crystallization method with high screening efficiency, low protein consumption and complete compatibility with high throughput screening system. (3) To determine the structure of lactate dehydrogenase complexed with NADH by x-ray protein crystallography to study its inherent structural properties. Firstly,… more
Date: August 9, 2006
Creator: Li, Fenglei
Partner: UNT Libraries Government Documents Department
open access

High Resolution Studies of the Origins of Polyatomic Ions in Inductively Coupled Plasma-Mass Spectrometry

Description: The inductively coupled plasma (ICP) is an atmospheric pressure ionization source. Traditionally, the plasma is sampled via a sampler cone. A supersonic jet develops behind the sampler, and this region is pumped down to a pressure of approximately one Torr. A skimmer cone is located inside this zone of silence to transmit ions into the mass spectrometer. The position of the sampler and skimmer cones relative to the initial radiation and normal analytical zones of the plasma is key to optimizing… more
Date: August 9, 2006
Creator: Ferguson, Jill Wisnewski
Partner: UNT Libraries Government Documents Department
open access

Recrystallization of high temperature superconductors

Description: Currently one of the most widely used high {Tc} superconductors is the Bi-based compounds Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub z} and Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub z} (known as BSCCO 2212 and 2223 compounds) with {Tc} values of about 85 K and 110 K respectively. Lengths of high performance conductors ranging from 100 to 1000 m long are routinely fabricated and some test magnets have been wound. An additional difficulty here is that although Bi-2212 and Bi-2223 phases exist over a wide… more
Date: May 9, 1996
Creator: Kouzoudis, D.
Partner: UNT Libraries Government Documents Department
open access

Plasma channel and Z-pinch dynamics for heavy ion transport

Description: A self stabilized, free standing, z-pinch plasma channel has been proposed to deliver the high intensity heavy ion beam from the end of a driver to the fuel target in a heavy ion inertial fusion power plant. The z-pinch relaxes emittance and energy spread requirements requiring a lower cost driver. A z-pinch transport would reduce the number of beam entry port holes to the target chamber from over a hundred to four as compared to neutralized ballistic focusing thus reducing the driver hardware … more
Date: July 9, 2002
Creator: Ponce-Marquez, David
Partner: UNT Libraries Government Documents Department
open access

Structural and Magnetothermal Properties of Compounds: Yb5SixGe4-x,Sm5SixGe4-x, EuO, and Eu3O4

Description: The family of R{sub 5}Si{sub x}Ge{sub 4-x} alloys demonstrates a variety of unique physical phenomena related to magneto-structural transitions associated with reversible breaking and reforming of specific bonds that can be controlled by numerous external parameters such as chemical composition, magnetic field, temperature, and pressure. Therefore, R{sub 5}Si{sub x}Ge{sub 4-x} systems have been extensively studied to uncover the mechanism of the extraordinary magneto-responsive properties inclu… more
Date: May 9, 2007
Creator: Ahn, Kyunghan
Partner: UNT Libraries Government Documents Department
open access

Soft-Lithographical Fabrication of Three-dimensional Photonic Crystals in the Optical Regime

Description: This dissertation describes several projects to realize low-cost and high-quality three-dimensional (3D) microfabrication using non-photolithographic techniques for layer-by-layer photonic crystals. Low-cost, efficient 3D microfabrication is a demanding technique not only for 3D photonic crystals but also for all other scientific areas, since it may create new functionalities beyond the limit of planar structures. However, a novel 3D microfabrication technique for photonic crystals implies the … more
Date: August 9, 2006
Creator: Lee, Jae-Hwang
Partner: UNT Libraries Government Documents Department
open access

Quantum groups, non-commutative differential geometry and applications

Description: The topic of this thesis is the development of a versatile and geometrically motivated differential calculus on non-commutative or quantum spaces, providing powerful but easy-to-use mathematical tools for applications in physics and related sciences. A generalization of unitary time evolution is proposed and studied for a simple 2-level system, leading to non-conservation of microscopic entropy, a phenomenon new to quantum mechanics. A Cartan calculus that combines functions, forms, Lie derivat… more
Date: December 9, 1993
Creator: Schupp, P.
Partner: UNT Libraries Government Documents Department
open access

Multipole Analysis of Circular Cylindircal Magnetic Systems

Description: This thesis deals with an alternate method for computing the external magnetic field from a circular cylindrical magnetic source. The primary objective is to characterize the magnetic source in terms of its equivalent multipole distribution. This multipole distribution must be valid at points close to the cylindrical source and a spherical multipole expansion is ill-equipped to handle this problem; therefore a new method must be introduced. This method, based upon the free-space Green's functio… more
Date: January 9, 2006
Creator: Selvaggi, J
Partner: UNT Libraries Government Documents Department
open access

Transient Eddy Current Response Due to a Subsurface Crack in a Conductive Plate

Description: Eddy current nondestructive evaluation (NDE) is usually carried out by exciting a time harmonic field using an inductive probe. However, a viable alternative is to use transient eddy current NDE in which a current pulse in a driver coil produces a transient .eld in a conductor that decays at a rate dependent on the conductivity and the permeability of the material and the coil configuration. By using transient eddy current, it is possible to estimate the properties of the conductive medium and … more
Date: August 9, 2006
Creator: Fu, Fangwei
Partner: UNT Libraries Government Documents Department
open access

Computational Fluid Dynamics Simulation of Fluidized Bed Polymerization Reactors

Description: Fluidized beds (FB) reactors are widely used in the polymerization industry due to their superior heat- and mass-transfer characteristics. Nevertheless, problems associated with local overheating of polymer particles and excessive agglomeration leading to FB reactors defluidization still persist and limit the range of operating temperatures that can be safely achieved in plant-scale reactors. Many people have been worked on the modeling of FB polymerization reactors, and quite a few models are … more
Date: August 9, 2006
Creator: Fan, Rong
Partner: UNT Libraries Government Documents Department
open access

Investigation of the phase equilibria and phase transformations associated with the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} superconductor

Description: The solid solution region and reaction kinetics of the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (2212) superconductor were examined as a function of temperature and oxygen partial pressure. Crystallization studies from the glassy and molten states were undertaken to determine the phase transformation and kinetics associated with the formation of 2212 and other competing phases. Crystallization of nominal 2212 glasses was found to proceed in two steps with the formation of Bi{sub 2}Sr{sub 2{minus}x… more
Date: December 9, 1993
Creator: Holesinger, T.
Partner: UNT Libraries Government Documents Department
open access

Homometallic and Heterometallic Antiferromagnetic Rings: Magnetic Properties Studied by Nuclear Magnetic Resonance

Description: The aim of the present thesis is to investigate the local magnetic properties of homometallic Cr{sub 8} antiferromagnetic (AFM) ring and the changes occurring by replacing one Cr{sup 3+} ion with diamagnetic Cd{sup 2+} (Cr{sub 7}Cd) and with Ni{sup 2+} (Cr{sub 7}Ni). In the heterometallic ring a redistribution of the local magnetic moment is expected in the low temperature ground state. We have investigated those changes by both {sup 53}Cr-NMR and {sup 19}F-NMR. We have determined the order of … more
Date: May 9, 2012
Creator: Casadei, Cecilia
Partner: UNT Libraries Government Documents Department
open access

Quantum Monte Carlo Calculations Applied to Magnetic Molecules

Description: We have calculated the equilibrium thermodynamic properties of Heisenberg spin systems using a quantum Monte Carlo (QMC) method. We have used some of these systems as models to describe recently synthesized magnetic molecules, and-upon comparing the results of these calculations with experimental data-have obtained accurate estimates for the basic parameters of these models. We have also performed calculations for other systems that are of more general interest, being relevant both for existing… more
Date: August 9, 2006
Creator: Engelhardt, Larry
Partner: UNT Libraries Government Documents Department
open access

The effect of spacer ribs on Ledinegg type flow instabilities

Description: An experimental program has been completed which evaluated the effect of a flow obstruction in a heated channel on the onset of flow instability (OBI). The test channel was rectangular (80 {times} 3 mm), heated on one surface, and equipped with view ports. Tests were conducted in a flow controlled mode at heat fluxes of 370 kW/M{sup 2}, and 610 kW/m{sup 2}. Direct comparisons were made between the demand curve minimum for the unobstructed channel and a channel equipped with a 2.07 mm wide rib t… more
Date: September 9, 1993
Creator: Coutts, D. A.
Partner: UNT Libraries Government Documents Department
open access

Designing of Metallic Photonic Structures and Applications

Description: In this thesis our main interest has been to investigate metallic photonic crystal and its applications. We explained how to solve a periodic photonic structure with transfer matrix method and when and how to use modal expansion method. Two different coating methods were introduced, modifying a photonic structure's intrinsic optical properties and rigorous calculation results are presented. Two applications of metallic photonic structures are introduced. For thermal emitter, we showed how to de… more
Date: August 9, 2006
Creator: Kim, Yong-Sung
Partner: UNT Libraries Government Documents Department
open access

New perspectives in physics beyond the standard model

Description: In 1934 Fermi postulated a theory for weak interactions containing a dimensionful coupling with a size of roughly 250 GeV. Only now are we finally exploring this energy regime. What arises is an open question: supersymmetry and large extra dimensions are two possible scenarios. Meanwhile, other experiments will begin providing definitive information into the nature of neutrino masses and CP violation. In this paper, we explore features of possible theoretical scenarios, and study the phenomenol… more
Date: September 9, 2000
Creator: Weiner, Neal Jonathan
Partner: UNT Libraries Government Documents Department
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