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 Degree Discipline: Physics
Distribution of Nighttime F-region Molecular Ion Concentrations and 6300 Å Nightglow Morphology

Distribution of Nighttime F-region Molecular Ion Concentrations and 6300 Å Nightglow Morphology

Date: December 1970
Creator: Brasher, William Ernest, 1939-
Description: The purpose of this study is two-fold. The first is to determine the dependence of the molecular ion profiles on the various ionospheric and atmospheric parameters that affect their distributions. The second is to demonstrate the correlation of specific ionospheric parameters with 6300 Å nightglow intensity during periods of magnetically quiet and disturbed conditions.
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A Study of Solar Cosmic Ray Flare Effects

A Study of Solar Cosmic Ray Flare Effects

Date: May 1971
Creator: Keath, Edwin P. (Edwin Paul), 1938-
Description: The purpose of this study is to determine the characteristics of the solar cosmic ray flux. This report describes the design and construction of a cosmic ray detector system used in this study and describes the analysis of the data obtained from these systems.
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On Chaos and Anomalous Diffusion in Classical and Quantum Mechanical Systems

On Chaos and Anomalous Diffusion in Classical and Quantum Mechanical Systems

Date: August 1998
Creator: Stefancich, Marco
Description: The phenomenon of dynamically induced anomalous diffusion is both the classical and quantum kicked rotor is investigated in this dissertation. We discuss the capability of the quantum mechanical version of the system to reproduce for extended periods the corresponding classical chaotic behavior.
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Synthesis and Study of Engineered Heterogenous Polymer Gels

Synthesis and Study of Engineered Heterogenous Polymer Gels

Date: August 1998
Creator: Chen, Yuanye
Description: This dissertation studies physical properties and technological applications of engineered heterogenous polymer gels. Such gels are synthesized based on modulation of gel chemical nature in space. The shape memory gels have been developed in this study by using the modulated gel technology. At room temperature, they form a straight line. As the temperature is increased, they spontaneously bend or curl into a predetermined shape such as a letter of the alphabet, a numerical number, a spiral, a square, or a fish. The shape changes are reversible. The heterogenous structures have been also obtained on the gel surface. The central idea is to cover a dehydrated gel surface with a patterned mask, then to sputter-deposit a gold film onto it. After removing the mask, a gold pattern is left on the gel surface. Periodical surface array can serve as gratings to diffract light. The grating constant can be continuously changed by the external environmental stimuli such as temperature and electric field. Several applications of gels with periodic surface arrays as sensors for measuring gel swelling ratio, internal strain under an uniaxial stress, and shear modulus have been demonstrated. The porous NIPA gels have been synthesized by suspension technique. Microstructures of newly ...
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Charge State Distributions in Molecular Dissociation

Charge State Distributions in Molecular Dissociation

Date: December 1998
Creator: Renfrow, Steven N. (Steven Neal)
Description: The present work provides charge state fractions that may be used to generate TEAMS relative sensitivity factors for impurities in semiconductor materials.
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Fluorine Adsorption and Diffusion in Polycrystalline Silica

Fluorine Adsorption and Diffusion in Polycrystalline Silica

Date: December 1998
Creator: Jin, Jian-Yue
Description: The measurement of fluorine penetration into archeological flint artifacts using Nuclear Reaction Analysis (NRA) has been reported to be a potential dating method. However, the mechanism of how fluorine is incorporated into the flint surface, and finally transported into the bulk is not well understood. This research focuses on the study of the fluorine uptake phenomenon of flint mineral in aqueous fluoride solutions. Both theoretical and experimental approaches have been carried out. In a theoretical approach, a pipe-diffusion model was used to simulate the complicated fluorine transportation problem in flint, in which several diffusion mechanisms may be involved.
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Two-Fold Role of Randomness: A Source of Both Long-Range Correlations and Ordinary Statistical Mechanics

Two-Fold Role of Randomness: A Source of Both Long-Range Correlations and Ordinary Statistical Mechanics

Date: December 1998
Creator: Rocco, A. (Andrea)
Description: The role of randomness as a generator of long range correlations and ordinary statistical mechanics is investigated in this Dissertation. The difficulties about the derivation of thermodynamics from mechanics are pointed out and the connection between the ordinary fluctuation-dissipation process and possible anomalous properties of statistical systems is highlighted.
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Criticality in Cooperative Systems

Criticality in Cooperative Systems

Date: May 2012
Creator: Vanni, Fabio
Description: Cooperative behavior arises from the interactions of single units that globally produce a complex dynamics in which the system acts as a whole. As an archetype I refer to a flock of birds. As a result of cooperation the whole flock gets special abilities that the single individuals would not have if they were alone. This research work led to the discovery that the function of a flock, and more in general, that of cooperative systems, surprisingly rests on the occurrence of organizational collapses. In this study, I used cooperative systems based on self-propelled particle models (the flock models) which have been proved to be virtually equivalent to sociological network models mimicking the decision making processes (the decision making model). The critical region is an intermediate condition between a highly disordered state and a strong ordered one. At criticality the waiting times distribution density between two consecutive collapses shows an inverse power law form with an anomalous statistical behavior. The scientific evidences are based on measures of information theory, correlation in time and space, and fluctuation statistical analysis. In order to prove the benefit for a system to live at criticality, I made a flock system interact with another similar ...
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Zinc Oxide Nanoparticles for Nonlinear Bioimaging, Cell Detection and Selective Cell Destruction

Zinc Oxide Nanoparticles for Nonlinear Bioimaging, Cell Detection and Selective Cell Destruction

Access: Use of this item is restricted to the UNT Community.
Date: May 2013
Creator: Urban, Ben E.
Description: Light matter interactions have led to a great part of our current understanding of the universe. When light interacts with matter it affects the properties of both the light and the matter. Visible light, being in the region that the human eye can "see," was one of the first natural phenomenon we used to learn about our universe. The application of fundamental physics research has spilled over into other fields that were traditionally separated from physics, being considered two different sciences. Current physics research has applications in all scientific fields. By taking a more physical approach to problems in fields such as chemistry and biology, we have furthered our knowledge of both. Nanocrystals have many interesting optical properties. Furthermore, the size and properties of nanocrystals has given them applications in materials ranging from solar cells to sunscreens. By understanding and controlling their interactions with systems we can utilize them to increase our knowledge in other fields of science, such as biology. Nanocrystals exhibit optical properties superior to currently used fluorescent dyes. By replacing molecular dyes with nanoparticles we can reduce toxicity, increase resolution and have better cellular targeting abilities. They have also shown to have toxicity to cancer and antibacterial ...
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A New Approach for Transition Metal Free Magnetic Sic: Defect Induced Magnetism After Self-ion Implantation

A New Approach for Transition Metal Free Magnetic Sic: Defect Induced Magnetism After Self-ion Implantation

Date: May 2013
Creator: Kummari, Venkata Chandra Sekhar
Description: SiC has become an attractive wide bandgap semiconductor due to its unique physical and electronic properties and is widely used in high temperature, high frequency, high power and radiation resistant applications. SiC has been used as an alternative to Si in harsh environments such as in the oil industry, nuclear power systems, aeronautical, and space applications. SiC is also known for its polytypism and among them 3C-SiC, 4H-SiC and 6H-SiC are the most common polytypes used for research purposes. Among these polytypes 4H-SiC is gaining importance due to its easy commercial availability with a large bandgap of 3.26 eV at room temperature. Controlled creation of defects in materials is an approach to modify the electronic properties in a way that new functionality may result. SiC is a promising candidate for defect-induced magnetism on which spintronic devices could be developed. The defects considered are of room temperature stable vacancy types, eliminating the need for magnetic impurities, which easily diffuse at room temperature. Impurity free vacancy type defects can be created by implanting the host atoms of silicon or carbon. The implantation fluence determines the defect density, which is a critical parameter for defect induced magnetism. Therefore, we have studied the influence ...
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