Degree Discipline

Solution based temperature of Perovskite-type oxide films and powders (open access)

Solution based temperature of Perovskite-type oxide films and powders

Conventional solid state reactions are diffusion limited processes that require high temperatures and long reaction times to reach completion. In this work, several solution based methods were utilized to circumvent this diffusion limited reaction and achieve product formation at lower temperatures. The solution methods studied all have the common goal of trapping the homogeneity inherent in a solution and transferring this homogeneity to the solid state, thereby creating a solid atomic mixture of reactants. These atomic mixtures can yield solid state products through {open_quotes}diffusionless{close_quotes} mechanisms. The effectiveness of atomic mixtures in solid state synthesis was tested on three classes of materials, varying in complexity. A procedure was invented for obtaining the highly water soluble salt, titanyl nitrate, TiO(NO{sub 3}){sub 2}, in crystalline form, which allowed the production of titanate materials by freeze drying. The freeze drying procedures yielded phase pure, nanocrystalline BaTiO{sub 3} and the complete SYNROC-B phase assemblage after ten minute heat treatments at 600{degrees}C and 1100{degrees}C, respectively. Two novel methods were developed for the solution based synthesis of Ba{sub 2}YCu{sub 3}O{sub 7-x} and Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}. Thin and thick films of Ba{sub 2}YCu{sub 3}O{sub 7-x} and Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} were synthesized by …
Date: April 1, 1995
Creator: McHale, J.M. Jr.
System: The UNT Digital Library
A Comparison of Cognitive Moral Development of Accounting Students at a Catholic University with Secular University Accounting Students (open access)

A Comparison of Cognitive Moral Development of Accounting Students at a Catholic University with Secular University Accounting Students

Previous research has shown that accountants may be inadequate moral reasoners. Concern over this trend caused the Treadway Commission (1987) and the Accounting Education Change Commission (1990) to call for greater integration of ethics into the student's training. Ponemon and Glazer (1990) found a difference in cognitive moral development (CMD) between accounting students at a public university and a private university with a liberal arts emphasis. This study expands Ponemon and Glazer's research by examining two liberal arts universities, one a private, secular institution and one a Catholic institution. The primary research question asks if Catholic university accounting students manifest greater CMD growth than secular university accounting students. Additionally, this study examines and compares the priority that accounting students from the different institutions place on ethical values versus economic values. It was expected that Catholic university accounting students would manifest both greater CMD growth and a greater concern for ethical values over economic values when compared with non-Catholic university accounting students. The study utilized a two-phase approach. In the first phase, an organizational study of two institutions was made to determine how each strives to integrate moral development into their accounting students' education. In the second phase, lower-division and senior …
Date: April 1998
Creator: Koeplin, John P. (John Peter)
System: The UNT Digital Library
Legacies of Power: The Cultural Heritage of Theological White Supremacy, A Case Study of Ku Klux Konfederatism in Denton County Texas, 1850-1930 (open access)

Legacies of Power: The Cultural Heritage of Theological White Supremacy, A Case Study of Ku Klux Konfederatism in Denton County Texas, 1850-1930

Undergraduate thesis exploring modern American racism as the result of the nation's legacy of theological white supremacy and its deep-rooted racial issues that remain unresolved because of the theo-mythologies embedded at the core of the nation's foundational fabric that have been and continue to be largely unaccounted for in corrective racial discourse through a case study of Denton, Texas. By employing localized interdisciplinary methodological approaches aimed at unveiling the theo-myth which underscores the modern American racial ontology, this study examines how theological white supremacy was homogenized into popular culture in Denton County Texas following the Civil War via neo-Confederate Ku Klux Klan movement, which the author calls Ku Klux Konfederatism, that continues its influence today through localized theo-political institutions, sociocultural systems and cultural 'norms.'
Date: April 20, 2020
Creator: Luther Rummel, Jessica Rae
System: The UNT Digital Library
Spectra of $gamma$-rays from capture of 2 eV to 9 x 10$sup 4$ eV neutrons by $sup 181$Ta (open access)

Spectra of $gamma$-rays from capture of 2 eV to 9 x 10$sup 4$ eV neutrons by $sup 181$Ta

Using new experimental techniques, the spectra of $gamma$-rays from the capture of neutrons by $sup 181$Ta were measured at the Livermore 100-MeV linac for neutrons from 2 eV to 9 x 10$sup 4$ eV with a (Ge(Li)-NaI) three-crystal spectrometer. Individual primary $gamma$-ray lines were resolved to 1778-keV excitation in $sup 182$Ta. Neutron resonances were resolved to 200-eV neutron energy. Data analysis techniques and codes were developed to extract positions and intensities of resolved transitions from the large data matrices accumulated in this experiment. Techniques were developed to unfold the unresolved $gamma$- ray spectra using the simple response of the three-crystal spectrometer. The resolved transition data were used to place 110 states with spin and parity assignments in the $sup 182$Ta level diagram below 1780-keV excitation. A set of 1240 E1 transition strengths were analyzed to extract 1.38 +- 0.11 degrees of freedom for the most likely chisquared fit to the distribution of widths. The E1 strength function was extracted for E/sub gamma/ = 4 to 6 MeV and compared with previous results. The $gamma$-ray spectra for E/sub gamma/ = 1.5 to 6.1 MeV were unfolded for neutron energy groups between 20 and 9 x 10$sup 4$ eV. Below 5-MeV $gamma$-ray …
Date: April 30, 1976
Creator: Stelts, M. L.
System: The UNT Digital Library
Electroweak Production of the Top Quark in the Run II of the D0 Experiment (open access)

Electroweak Production of the Top Quark in the Run II of the D0 Experiment

The work exposed in this thesis deals with the search for electroweak production of top quark (single top) in proton-antiproton collisions at {radical}s = 1.96 TeV. This production mode has not been observed yet. Analyzed data have been collected during the Run II of the D0 experiment at the Fermilab Tevatron collider. These data correspond to an integrated luminosity of 370 pb{sup -1}. In the Standard Model, the decay of a top quark always produce a high momentum bottom quark. Therefore bottom quark jets identification plays a major role in this analysis. The large lifetime of b hadrons and the subsequent large impact parameters relative to the interaction vertex of charged particle tracks are used to tag bottom quark jets. Impact parameters of tracks attached to a jet are converted into the probability for the jet to originate from the primary vertex. This algorithm has a 45% tagging efficiency for a 0.5% mistag rate. Two processes (s and t channels) dominate single top production with slightly different final states. The searched signature consists in 2 to 4 jets with at least one bottom quark jet, one charged lepton (electron or muon) and missing energy accounting for a neutrino. This final …
Date: April 1, 2006
Creator: Clement, Benoit & /Strasbourg, IReS
System: The UNT Digital Library
The Effect of Initial Conditions on the Nonlinear Evolution of Perturbed Interfaces Driven by Strong Blast Waves (open access)

The Effect of Initial Conditions on the Nonlinear Evolution of Perturbed Interfaces Driven by Strong Blast Waves

In core-collapse supernovae, strong blast waves drive interfaces susceptible to Rayleigh-Taylor (RT), Richtmyer-Meshkov (RM), and Kelvin-Helmholtz (KH) instabilities. In addition, perturbation growth can result from material expansion in large-scale velocity gradients behind the shock front. Laser-driven experiments are designed to produce a strongly shocked interface whose evolution is a scaled version of the unstable hydrogen-helium interface in core-collapse supernovae such as SN 1987A. The ultimate goal of this research is to develop an understanding of the effect of hydrodynamic instabilities and the resulting transition to turbulence on supernovae observables that remain as yet unexplained. In this dissertation, we present a computational study of unstable systems driven by high Mach number shock and blast waves. Using multi-physics radiation hydrodynamics codes and theoretical models, we consider the late nonlinear instability evolution of single mode, few mode, and multimode interfaces. We rely primarily on 2D calculations but present recent 3D results as well. For planar multimode systems, we show that compressibility effects preclude the emergence of a regime of self-similar instability growth independent of the initial conditions (IC's) by allowing for memory of the initial conditions to be retained in the mix-width at all times. The loss of transverse spectral information is demonstrated, …
Date: April 27, 2004
Creator: Miles, A
System: The UNT Digital Library
Relative Yields of Nitrogen-17 Produced by 190-Mev Deuteron Bombardment (open access)

Relative Yields of Nitrogen-17 Produced by 190-Mev Deuteron Bombardment

"Yields of N¹⁷ relative to that produced in LiF have been measured in the 190-Mev deflected deuteron and the 380-Mev alpha beams of the 184-inch synchrocyclotron. The measurements have been performed in all the light elements from 0 through V, with the exception of Sc and the noble gases. In addition, yields were measured in the separated isotopes of Mg...Comparisons are made with other types of yield studies performed with neutrons and protons, and the areas of agreement are noted."
Date: April 13, 1955
Creator: Chupp, Warren William
System: The UNT Digital Library
Instrumentation for Continuously Recording Plasma-Induced Frequency Shifts of Two Microwave Cavity Resonances (open access)

Instrumentation for Continuously Recording Plasma-Induced Frequency Shifts of Two Microwave Cavity Resonances

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Date: April 1, 1974
Creator: Evans, R. P.
System: The UNT Digital Library
Classical Inspiration and Modern Expression: Greek Art Turned Fauve, Constructivist, Dada, and Pop (open access)

Classical Inspiration and Modern Expression: Greek Art Turned Fauve, Constructivist, Dada, and Pop

Senior colloquium written by a student in the UNT Honors College discussing Greek sculpture and architecture as filtered through the Fauve, Constructivist, Dada, and Pop artistic movements. The author takes examples of Grecian sculpture, recreates them in each of the other styles, and discusses the results.
Date: April 27, 1991
Creator: Capen, Sheri
System: The UNT Digital Library
Search for new physics in electron-tau final states in proton - antiproton collisions at 1.96 TeV (open access)

Search for new physics in electron-tau final states in proton - antiproton collisions at 1.96 TeV

During the last decades, particle physicists have studied the tiniest building blocks of matter--the quarks and the leptons--and the forces between them in great detail. From these experiments, a theoretical framework has been built that describes the observed results with high precision. The achievement of this theory, which is referred to as the Standard Model of elementary particle physics, was the elaboration of a unified description of the strong, weak and electromagnetic forces in the framework of quantum gauge-field theories. Moreover, the Standard Model combines the weak and electromagnetic forces in a single electroweak gauge theory. The fourth force which is realized in nature, gravity, is too weak to be observable in laboratory experiments carried out in high-energy particle physics and is not part of the Standard Model. Although the Standard Model has proven highly successful in correlating a huge amount of experimental results, a key ingredient is as yet untested: the origin of electroweak symmetry breaking. Currently, the only viable ansatz that is compatible with observation is the Higgs mechanism. It predicts the existence of a scalar particle, called the Higgs boson, and the couplings to the fundamental Standard Model particles, however not its mass. An upper limit on …
Date: April 1, 2006
Creator: Noeding, Carsten
System: The UNT Digital Library
Search for large extra dimensions in the exclusive photon + missing energy channel in p anti-p collisions (open access)

Search for large extra dimensions in the exclusive photon + missing energy channel in p anti-p collisions

A search was conducted for evidence of large extra dimensions (LED) at Fermi National Accelerator Laboratory's Tevatron using the D0 detector. The Tevatron is a p{bar p} collider at a center of mass energy of 1.96 TeV. Events with particles escaping into extra dimensions will have large missing energy. The search was carried out using data from a total luminosity of 197 {+-} 13 pb{sup -1} with an observable high transverse momentum photon and a large transverse missing energy. The 70 observed events are consistent with photons produced by standard known reactions plus other background processes produced by cosmic muons. The mass limits on the fundamental mass scale at 95% confidence level for large extra dimensions of 2, 4, 6 and 8 are 500 GeV, 581 GeV, 630 GeV, and 668 GeV respectively.
Date: April 1, 2006
Creator: Lazoflores, Jose A.
System: The UNT Digital Library
Measurement of cross-section (p anti-p --> Z0) x BF (Z0 --> tau anti-tau) at s**(1/2) = 1.96-TeV using the D0 detector at the Tevatron (open access)

Measurement of cross-section (p anti-p --> Z0) x BF (Z0 --> tau anti-tau) at s**(1/2) = 1.96-TeV using the D0 detector at the Tevatron

In this thesis the first measurement of {sigma}(p{bar p}) {yields} Z{sup 0} {yields} {tau}{bar {tau}} with the D0 detector at the Tevatron is presented. The tau pair candidates are recorded by the D0 detector using p{bar p} interactions at a center-of-mass energy of 1.96 TeV. Events in which one tau decays into a muon and the other tau final state is hadronic with one charged particle are selected for this analysis. The selection criteria for the hadronic tau decay are based on the tau final state, hence for two channels of one-prong taus: single charged pion ({tau}{sub {pi}}) and rho decays ({tau}{sub {rho}}). The selection is based on simple cuts on a number of discriminating variables and the cut values have been optimized for the best cross section measurement. Of hadronic tau candidates that have been reconstructed as {tau}{sub {pi}} candidates, 0.801 {+-} 0.017 {+-} 0.066 pass the selection cut; in the case of {tau}{sub {rho}} taus, the selection efficiency is 0.676 {+-} 0.009 {+-} 0.009. Of all QCD jets that are reconstructed as hadronic tau candidates, 0.0093 {+-} 0.0002 pass the {tau}{sub {pi}} selection cuts and 0.0122 {+-} 0.0002 the {tau}{sub {rho}} cuts. The cross section has been measured …
Date: April 1, 2004
Creator: Duensing, Silke & U., /Nijmegen
System: The UNT Digital Library
WW production cross section measurement and limits on anomalous trilinear gauge couplings at sqrt(s) = 1.96-TeV (open access)

WW production cross section measurement and limits on anomalous trilinear gauge couplings at sqrt(s) = 1.96-TeV

The cross section for WW production is measured and limits on anomalous WW{gamma} and WWZ trilinear gauge couplings are set using WW {yields} ee/e{mu}/{mu}{mu} events collected by the Run II D0 detector at the Fermilab Tevatron Collider corresponding to 1 fb{sup -1} of integrated luminosity at {radical}s = 1.96 TeV. Across the three final states, 108 candidate events are observed with 40.8 {+-} 3.8 total background expected, consistent with {sigma}(p{bar p} {yields} WW) = 11.6 {+-} 1.8(stat) {+-} 0.7(syst) {+-} 0.7(lumi) pb. Using a set of SU(2){sub L} {direct_product} U(1){sub Y} conserving constraints, the one-dimensional 95% C.L. limits on trilinear gauge couplings are -0.63 < {Delta}{kappa}{sub {gamma}} < 0.99, -0.15 < {lambda}{sub {gamma}} < 0.19, and -0.14 < {Delta}g{sub 1}{sup Z} < 0.34.
Date: April 1, 2008
Creator: Cooke, Michael P. & U., /Rice
System: The UNT Digital Library