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  Access Rights: Use restricted to UNT Community
  Partner: UNT Libraries
 Decade: 2010-2019
 Degree Level: Master's
 Collection: UNT Theses and Dissertations
Ab Initio and Density Functional Investigation of the Conformer Manifold of Melatonin and a Proposal for a Simple Dft-based Diagnostic for Nondynamical Correlation

Ab Initio and Density Functional Investigation of the Conformer Manifold of Melatonin and a Proposal for a Simple Dft-based Diagnostic for Nondynamical Correlation

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Date: August 2013
Creator: Fogueri, Uma
Description: In this work we address two problems in computational chemistry relevant to biomolecular modeling. In the first project, we consider the conformer space of melatonin as a a representative example of “real-life” flexible biomolecules. Geometries for all 52 unique conformers are optimized using spin-component scaled MP2, and then relative energies are obtained at the CCSD (T) level near the complete basis set limit. These are then used to validate a variety of DFT methods with and without empirical dispersion corrections, as well as some lower-level ab initio methods. Basis set convergence is found to be relatively slow due to internal C-H…O and C-H…N contacts. Absent dispersion corrections, many DFT functionals will transpose the two lowest conformers. Dispersion corrections resolve the problem for most functionals. Double hybrids yield particularly good performance, as does MP2.5. In the second project, we propose a simple DFT-based diagnostic for nondynamical correlation effects. Aλ= (1-TAE [ΧλC]/TAE[XC])/λ where TAE is the total atomization energy, XC the “pure” DFT exchange-correlation functional, and ΧλC the corresponding hybrid with 100λ% HF-type exchange. The diagnostic is a good predictor for sensitivity of energetics to the level of theory, unlike most of the wavefunction-based diagnostics. For GGA functionals, Aλ values approaching unity ...
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The Academic Steroid: Nonmedical Use of Prescription Stimulants at a North Texas University

The Academic Steroid: Nonmedical Use of Prescription Stimulants at a North Texas University

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Date: December 2014
Creator: Pennington, Cody W
Description: The goal of this study was to determine the extent, motivations, and justifications of nonmedical prescription stimulant use among the population at a large public university in the North Texas region. Participants consisted of 526 undergraduate students enrolled at the studied university during the spring and summer 2014 semesters. The findings of the study suggest that the nonmedical use by students was higher than the findings in much of the current literature, but was within the parameters established in the literature. The primary motivation for nonmedical use was academic in nature and was justified by moderation of nonmedical use to strategic academic times.
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Acute Effects of the Antibiotic Streptomycin on Neural Network Activity and Pharmacological Responses

Acute Effects of the Antibiotic Streptomycin on Neural Network Activity and Pharmacological Responses

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Date: December 2014
Creator: Zeng, Wei Rong
Description: The purpose of this study is to find out that if antibiotic streptomycin decreases neuronal network activity or affects the pharmacological responses. The experiments in this study were conducted via MEA (multi-electrode array) technology which records neuronal activity from devices that have multiple small electrodes, serve as neural interfaces connecting neurons to electronic circuitry. The result of this study shows that streptomycin lowered the spike production of neuronal network, and also, sensitization was seen when neuronal network pre-exposed to streptomycin.
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Anchor Nodes Placement for Effective Passive Localization

Anchor Nodes Placement for Effective Passive Localization

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Date: August 2010
Creator: Pasupathy, Karthikeyan
Description: Wireless sensor networks are composed of sensor nodes, which can monitor an environment and observe events of interest. These networks are applied in various fields including but not limited to environmental, industrial and habitat monitoring. In many applications, the exact location of the sensor nodes is unknown after deployment. Localization is a process used to find sensor node's positional coordinates, which is vital information. The localization is generally assisted by anchor nodes that are also sensor nodes but with known locations. Anchor nodes generally are expensive and need to be optimally placed for effective localization. Passive localization is one of the localization techniques where the sensor nodes silently listen to the global events like thunder sounds, seismic waves, lighting, etc. According to previous studies, the ideal location to place anchor nodes was on the perimeter of the sensor network. This may not be the case in passive localization, since the function of anchor nodes here is different than the anchor nodes used in other localization systems. I do extensive studies on positioning anchor nodes for effective localization. Several simulations are run in dense and sparse networks for proper positioning of anchor nodes. I show that, for effective passive localization, the ...
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“The Angular Degrees of Freedom” and Other Stories

“The Angular Degrees of Freedom” and Other Stories

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Date: December 2014
Creator: Feagin, Aprell McQueeney
Description: The preface, " Performing Brain Surgery: The Problematic Nature of Endings in Short Fiction," deals with the many and varied difficulties short story writers encounter when attempting to craft endings. Beginning with Raymond Carver and Flannery O’Connor and moving to my own work, I discuss some of the obscure criteria used to designate a successful ending, as well as the more concrete idea of the ending as a unifying element. Five short stories make up the remainder of this thesis: "In-between Girls," "Crocodile Man," "Surprising Things, Sometimes Amusing," "Good Jewelry," and "The Angular Degrees of Freedom."
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Challenge the Silence

Challenge the Silence

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Date: August 2012
Creator: Peterson, Erica
Description: This collection of personal essays about incest, abuse, and depression explores the lasting effects of an invisible childhood. The essays follow the protagonist from the age of five to her early twenties. Her brother, at a young age, becomes sexually abusive of her and her sisters, and her parents fail to protect their daughters. The family is divided as the older girls strive to defend their little sisters, while their parents attempt to excuse their son. When her brother is finally sent away, the protagonist is left to salvage what remains of her relationships with her parents.
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A Chorus of Trees

A Chorus of Trees

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Date: August 2010
Creator: Lyons, Renée Kathleen
Description: This two-part thesis includes a critical preface and a collection of my poems. Using three poems-Louise Glück's "Lullaby," Bob Hicok's "Poem for My Mother's Hysterectomy," and Nick Flynn's "Memento Mori"-the critical preface examines how, in poetry, the transformation of a body negotiates trauma and triggers a conceptual shift, the creation and revision of identity, and the release of the duende's inspirational force. The collection of poetry that follows seeks to transfigure the body as a way to explore the nuanced traumas of human experience.
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El Cine De Terror Español Como Espejo De La Cultura Española

El Cine De Terror Español Como Espejo De La Cultura Española

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Date: May 2014
Creator: Donahue, Tyler
Description: This study traces the history and culture of Spain as seen through the lens of the nation´s production of horror cinema. Starting from the boom of Spanish horror film in the early 1960s, the thesis compares and contrasts the political and social aspects of Spanish society throughout three distinct eras of the 20th century: 1962 – 1975 (the boom of Spanish horror film through the Franco dictatorship), 1975 – 1999 (the transition to democracy through the end of the 20th century) and 2000 – present (the 21st century). Movies as diverse as Gritos en la noche (1962, Jesús Franco), ¿Quién puede matar a un niño? (1976, Narciso Ibáñez Serrador) and Angustia (1987, Bigas Luna) are framed by culturally-related anectodes as well as correlations to their respective social environments. Special attention has been paid to the production and release of each film, especially in regards to censorship during the Franco dictatorship. The results show that Spanish horror cinema has acted as a true mirror to culture, society and politics in its native country throughout the 20th century and that this trend will likely extend in to the future.
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A Comprehensive Modeling Framework for Airborne Mobility

A Comprehensive Modeling Framework for Airborne Mobility

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Date: December 2013
Creator: Xie, Junfei
Description: Mobility models serve as the foundation for evaluating and designing airborne networks. Due to the significant impact of mobility models on the network performance, mobility models for airborne networks (ANs) must realistically capture the attributes of ANs. In this paper, I develop a comprehensive modeling framework for ANs. The work I have done is concluded as the following three parts. First, I perform a comprehensive and comparative analysis of AN mobility models and evaluate the models based on several metrics: 1) networking performance, 2) ability to capture the mobility attributes of ANs, 3) randomness levels and 4) associated applications. Second, I develop two 3D mobility models and realistic boundary models. The mobility models follow physical laws behind aircraft maneuvering and therefore capture the characteristics of aircraft trajectories. Third, I suggest an estimation procedure to extract parameters in one of the models that I developed from real flight test data. The good match between the estimated trajectories and real flight trajectories also validate the suitability of the model. The mobility models and the estimation procedure lead to the creation of “realistic” simulation and evaluation environment for airborne networks.
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Control and Automation of a Heat Shrink Tubing Process

Control and Automation of a Heat Shrink Tubing Process

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Date: August 2014
Creator: Yousefi Darani, Shahrokh
Description: Heat shrink tubing is used to insulate wire conductors, protect wires, and to create cable entry seals in wire harnessing industries. Performing this sensitive process manually is time consuming, the results are strongly dependent on the operator’s expertise, and the process presents safety concerns. Alternatively, automating the process minimizes the operators’ direct interaction, decreases the production cost over the long term, and improves quantitative and qualitative production indicators dramatically. This thesis introduces the automation of a heat shrink tubing prototype machine that benefits the wire harnessing industry. The prototype consists of an instrumented heat chamber on a linear positioning system, and is fitted with two heat guns. The chamber design allows for the directing of hot air from the heat guns onto the wire harness uniformly through radially-distributed channels. The linear positioning system is designed to move the heat chamber along the wire harness as the proper shrinkage temperature level is reached. Heat exposure time as a major factor in the heat shrink tubing process can be governed by controlling the linear speed of the heat chamber. A control unit manages the actuator position continuously by measuring the chamber’s speed and temperature. A model-based design approach is followed to design ...
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