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Development of a Hybrid Molecular Ultraviolet Photodetector based on Guanosine Derivatives

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Modern studies on charge transfer reaction and conductivity measurements of DNA have shown that the electrical behavior of DNA ranges from that of an insulator to that of a wide bandgap semiconductor. Based on this property of DNA, a metal-semiconductor-metal photodetector is fabricated using a self-assembled layer of deoxyguanosine derivative (DNA base) deposited between gold electrodes. The electrodes are lithographically designed on a GaN substrate separated by a distance L (50nm < L < 100nm). This work examines the electrical and optical properties of such wide-bandgap semiconductor based biomaterial systems for their potential application as photodetectors in the UV region wherein most of the biological agents emit. The objective of this study was to develop a biomolecular electronic device and design an experimental setup for electrical and optical characterization of a novel hybrid molecular optoelectronic material system. AFM results proved the usage of Ga-Polar substrate in conjugation with DG molecules to be used as a potential electronic based sensor. A two-terminal nanoscale biomolectronic diode has been fabricated showing efficient rectification ratio. A nanoscale integrated ultraviolet photodetector (of dimensions less than 100 nm) has been fabricated with a cut-off wavelength at ~ 320 nm.
Date: December 2005
Creator: Liddar, Harsheetal
System: The UNT Digital Library

Art Criticism and the Gendering of Lee Bontecou's Art, ca. 1959 - 1964

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This thesis identifies and analyzes gendering in the art writing devoted to Lee Bontecou's metal and canvas sculptures made from the 1959 - 1964. Through a careful reading of reviews and articles written about Bontecou's constructions, this thesis reconstructs the context of the art world in the United States at mid-century and investigates how cultural expectations regarding gender directed the reception of Bontecou's art, beginning in 1959 and continuing through mid-1960s. Incorporating a description of the contemporaneous cultural context with description of the constructions and an analysis of examples of primary writing, the thesis chronologically follows the evolution of a tendency in art writing to associate gender-specific motivation and interpretation to one recurring feature of Bontecou's works.
Date: December 2005
Creator: Estrada-Berg, Victoria
System: The UNT Digital Library

Surface Plasmon Based Nanophotonic Optical Emitters

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Group- III nitride based semiconductors have emerged as the leading material for short wavelength optoelectronic devices. The InGaN alloy system forms a continuous and direct bandgap semiconductor spanning ultraviolet (UV) to blue/green wavelengths. An ideal and highly efficient light-emitting device can be designed by enhancing the spontaneous emission rate. This thesis deals with the design and fabrication of a visible light-emitting device using GaN/InGaN single quantum well (SQW) system with enhanced spontaneous emission. To increase the emission efficiency, layers of different metals, usually noble metals like silver, gold and aluminum are deposited on GaN/InGaN SQWs using metal evaporator. Surface characterization of metal-coated GaN/InGaN SQW samples was carried out using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Photoluminescence is used as a tool for optical characterization to study the enhancement in the light emitting structures. This thesis also compares characteristics of different metals on GaN/InGaN SQW system thus allowing selection of the most appropriate material for a particular application. It was found out that photons from the light emitter couple more to the surface plasmons if the bandgap of former is close to the surface plasmon resonant energy of particular metal. Absorption of light due to gold reduces the …
Date: December 2005
Creator: Vemuri, Padma Rekha
System: The UNT Digital Library

Water systems, water policy, and Karst terrain: An analysis of the complex relationships between geology, economy, public perceptions, and policy in southern Trelawny, Jamaica.

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Jamaica has an abundance of freshwater resources, however, a lack of infrastructure makes treated, piped water inaccessible in many areas. Through literature reviews and site visits, this thesis is an analysis of how the people and land, and money and policy, interact with one another in relation to Jamaica's freshwater resources and water infrastructure. Special attention is given to the island's type-example Cockpit karst geology; tourism, mining, and farming's relation to this karst; types of water delivery systems in rural southern Trelawny's Cockpit Country; southern Trelawny residents' perceptions of the water situation; and policy and development goals in the context of Jamaica and southern Trelawny. I hope to bring attention to the unique social, geologic, and developmental context of water in Jamaica, and more specifically to garner attention for major water infrastructure improvements in south Trelawny. A number of recommendations for improvements with policy and infrastructure are made.
Date: December 2005
Creator: McCall, Sarah
System: The UNT Digital Library
Hydrological Impacts of Urbanization: White Rock Creek, Dallas Texas (open access)

Hydrological Impacts of Urbanization: White Rock Creek, Dallas Texas

This research project concerns changes in hydrology resulting from urbanization of the upper sub-basin of the White Rock Creek Watershed in Collin and Dallas Counties, Texas. The objectives of this study are: to calculate the percent watershed urbanized for the period of 1961 through 1968 and the period of 2000 through 2005; to derive a 1960s average unit hydrograph and a 2000s average unit hydrograph; and, to use the two averaged hydrographs to develop a range of hypothetical storm scenarios to evaluate how the storm response of the watershed has changed between these two periods. Results of this study show that stormflow occurs under lower intensity precipitation in the post-urbanized period and that stormflow peaks and volumes are substantially larger compared to the pre-urbanized period. It is concluded that changes in watershed surface conditions resulting from urbanization have lowered the precipitation-intensity threshold that must be surpassed before storm run-off is generated.
Date: December 2005
Creator: Vicars, Julie Anne Groening
System: The UNT Digital Library
Capacity and Throughput Optimization in Multi-cell 3G WCDMA Networks (open access)

Capacity and Throughput Optimization in Multi-cell 3G WCDMA Networks

User modeling enables in the computation of the traffic density in a cellular network, which can be used to optimize the placement of base stations and radio network controllers as well as to analyze the performance of resource management algorithms towards meeting the final goal: the calculation and maximization of network capacity and throughput for different data rate services. An analytical model is presented for approximating the user distributions in multi-cell third generation wideband code division multiple access (WCDMA) networks using 2-dimensional Gaussian distributions by determining the means and the standard deviations of the distributions for every cell. This model allows for the calculation of the inter-cell interference and the reverse-link capacity of the network. An analytical model for optimizing capacity in multi-cell WCDMA networks is presented. Capacity is optimized for different spreading factors and for perfect and imperfect power control. Numerical results show that the SIR threshold for the received signals is decreased by 0.5 to 1.5 dB due to the imperfect power control. The results also show that the determined parameters of the 2-dimensional Gaussian model match well with traditional methods for modeling user distribution. A call admission control algorithm is designed that maximizes the throughput in multi-cell …
Date: December 2005
Creator: Nguyen, Son
System: The UNT Digital Library
The glocalization and acculturation of HIV/AIDS: The role of communication in the control and prevention of the epidemic in Uganda. (open access)

The glocalization and acculturation of HIV/AIDS: The role of communication in the control and prevention of the epidemic in Uganda.

Grounded in the social constructivism tradition, this study examined the role of communication in the glocalization and acculturation of HIV/AIDS by a section of sexually active Ugandans then living in Rakai district during the advent of the epidemic in 1982. Sixty-four women and men participated in ten focus group discussions in Rakai and Kampala districts. Five themes emerged from the data highlighting how individuals and communities made sense of the epidemic, the omnipresence of death, how they understood the HIV/AIDS campaign, and how they are currently coping with its backlash. The study concludes that HIV/AIDS is socially constructed and can be understood better from local perspectives rather than from a globalized view. The study emphasizes the integration of cultural idiosyncrasies in any health communication campaigns to realize behavioral change.
Date: December 2005
Creator: Muwanguzi, Samuel
System: The UNT Digital Library
A New Approach to Texas Groundwater Management: An Environmental Justice Argument to Challenge the Rule of Capture (open access)

A New Approach to Texas Groundwater Management: An Environmental Justice Argument to Challenge the Rule of Capture

Texas is the last remaining state to utilize the rule of capture, a doctrine based on English Common Law, as a means of regulating groundwater resources. Many of the western states originally used the rule of capture to regulate their groundwater resources, but over time, each of these states replaced the rule of capture with other groundwater laws and regulations. The Texas Water Development Board (TWDB) State Water Plan, Water for Texas-2002, warned Texans if current water usage and laws do not change, there will be an unmet need of 7.5 million acre-feet of water annually by 2050. This caused individuals in state and local government to begin asking the question, "How are we going to meet our future water needs?" In the search for a solution to the water shortage problem people have divided themselves into two groups: one wants to consider the implementation of water conservation measures to reduce per capita water use in order to meet future demands; while the other group wants to spend millions of dollars to build reservoirs and dams along with laying thousands of miles of pipeline to move water around the state. The fact that Texas has yet to come up with …
Date: December 2005
Creator: Purvis, Jody
System: The UNT Digital Library
Synthesis and X-ray Diffraction Structures of 2-(2-thienylidene)-4,5-bis-(diphenylphosphino)-4-cyclopenten-1,3-dione and fac-BrRe(CO)3[2-(2-thienylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione] (open access)

Synthesis and X-ray Diffraction Structures of 2-(2-thienylidene)-4,5-bis-(diphenylphosphino)-4-cyclopenten-1,3-dione and fac-BrRe(CO)3[2-(2-thienylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione]

Treatment of 4,5 bis-(diphenylphosphino)-cyclopenten-1,3 dione with thiophene carboxyaldehyde in dichloromethane, in the presence of molecular sieves results in a new heterocyclic compound, 2-(2-thienylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (ligand), with a high yield. This product was characterized by using both IR and NMR spectroscopic techniques and the solid-state structure of the ligand was determined using X-ray crystallography. When the ligand was treated with the solvent stabilized intermediate of ReBr(CO)5 with THF, a monomeric metal complex, fac-BrRe(CO)3[2-(2-thienylidene)-4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione] was the result. The solid-state structure of the monomeric metal complex was determined using X-ray crystallography. Photolysis and thermolysis studies of the complex will be further explored.
Date: December 2005
Creator: Pingali, Aparna
System: The UNT Digital Library
Forsythia (open access)

Forsythia

Forsythia is a collection of poetry that examines the transformative power of observation.
Date: December 2005
Creator: Pike, Brianna J.
System: The UNT Digital Library
The Life History and Contributions to the Ecology of Camelobaetidius variabilis Wiersema 1998 (Ephemeroptera: Baetidae) in Honey Creek, Oklahoma (open access)

The Life History and Contributions to the Ecology of Camelobaetidius variabilis Wiersema 1998 (Ephemeroptera: Baetidae) in Honey Creek, Oklahoma

A study of the life history and ecology of Camelobaetidius variabilis was conducted in Honey Creek, OK from February 2003-April 2004. Nymph development was assessed using changes in external morphology. Laboratory reared nymphs were used to calculate number of degree days to complete development (772 degree days at 20.8° C ±.38° C), which was used to determine voltinism. Field collected nymph microhabitat distribution was used in assessing microhabitat distribution. Nymphal thermoregulation was assessed during the winter and spring by comparing nymphal numbers present in shaded and un-shaded habitats. Camelobaetidius variabilis nymphs showed preference for algal microhabitats during the spring and leaf packs in the winter. Nymphs inhabited leaf packs to increase metabolic rate during the winter. Increased temperatures aid in development of nymphs. Camelobaetidius variabilis exhibited a multivoltine life cycle with six overlapping generations.
Date: December 2005
Creator: Perry, Heather A.
System: The UNT Digital Library
Wine & Beer (open access)

Wine & Beer

Wine & Beer tells the story of childhood friends Brian and Vic who, after spending some time apart, deal with the tensions of sexual orientation after they attempt to renew their friendship. At the beginning it seems that Vic's sexuality will not be a problem, but after the two friends hang out in a local bar, Brian realizes his hometown is not as tolerant as he is. The couple is faced with family and social concerns, which goes from the argumentative to the violent. As the main characters try to mingle with the conservative town, they soon find themselves looked upon by a small town resistant to change. This 35-minute film explores homophobia and violence in small town USA.
Date: December 2005
Creator: Maysonet, Joel R.
System: The UNT Digital Library
Children, Adolescents, and English Witchcraft (open access)

Children, Adolescents, and English Witchcraft

One area of history that historians have ignored is that of children and their relationship to witchcraft and the witch trials. This thesis begins with a survey of historical done on the general theme of childhood, and moves on to review secondary literature about children and the continental witch trials. The thesis also reviews demonological theory relating to children and the roles children played in the minds of continental and English demonologists. Children played various roles: murder victims, victims of dedication to Satan, child-witches, witnesses for the prosecution, victims of bewitchment or possession, and victims of seduction into witchcraft. The final section of the thesis deals with children and English witchcraft. In England children tended to play the same roles as described by the demonologists.
Date: December 2005
Creator: Martin, Lisa A.
System: The UNT Digital Library
GIS Modeling of Wetlands Elevation Change in Response to Projected Sea Level Rise, Trinity Bay, Texas (open access)

GIS Modeling of Wetlands Elevation Change in Response to Projected Sea Level Rise, Trinity Bay, Texas

This study is a test of a methodology to predict changes in elevation and shoreline position of coastal wetlands in Trinity Bay, Texas, in response to projected sea level rise. The study combines numerical modeling and a geographic information system. A smoothing technique is used on a United States Geographical Survey (USGS) digital elevation model to obtain elevation profiles that more accurately represent the gently sloping wetlands surface. The numerical model estimates the expected elevation change by raster cell based on input parameters of predicted sea level rise, mineral and organic sedimentation rates, and sediment autocompaction rates. A GIS is used to display predicted elevation changes and changes in shoreline position as a result of four projected sea level rise scenarios over the next 100 years. Results demonstrate that this numerical model and methodology are promising as a technique of modeling predicted elevation change and shoreline migration in wetlands. The approach has potential utility in coastal management applications.
Date: December 2005
Creator: Lee, Erica Anne
System: The UNT Digital Library
Bach's Mass in B minor: An Analytical Study of Parody Movements and their Function in the Large-Scale Architectural Design of the Mass (open access)

Bach's Mass in B minor: An Analytical Study of Parody Movements and their Function in the Large-Scale Architectural Design of the Mass

Most studies of the Mass in B Minor deal with the history of the work, its reception history, primary sources, performance practice issues, rhetoric, and even theological and numerical symbolism. However, little research focuses on an in-depth analysis of the music itself. Of the few analytical studies undertaken, to date only a limited number attempt to explain Bach's use of parody technique or unity in the whole composition. This thesis focuses on understanding three primary concerns in regards to the Mass in B minor: to comprehend how preexistent material was adapted to the context of the Mass, how this material functions in the network of the entire composition, and how unity is achieved by means of large-scale voice leading. The results of this study not only provide new information about this monument of Western music, but also provide insight to the deep sense of large-scale structure in Bach's work.
Date: December 2005
Creator: Pérez Torres, René
System: The UNT Digital Library
Customer Perceptions of Fairness in Hotel Revenue Management. (open access)

Customer Perceptions of Fairness in Hotel Revenue Management.

The purpose of the study was to determine customer perceptions of fairness concerning pricing policies charged by the hotel industry, and to examine how different outcomes in pricing policies affect customer perceptions of fairness. Convenience-Interception survey sampling was used to collect 460 sample data at the Dallas Love Field Airport. After analyzing data, one can infer that when revenue management information was provided, customers are satisfied. Further, age, education, Airline FFP enrolled and redeem miles, and pricing based on marketing channels plays an imperative role in this study.
Date: December 2005
Creator: Sanghavi, Punit
System: The UNT Digital Library
Attrition in Longitudinal Studies Using Older Adults: A Meta-Analysis (open access)

Attrition in Longitudinal Studies Using Older Adults: A Meta-Analysis

Longitudinal methods have become an improved and essential means of measuring intra-individual change over time. Yet one of the greatest and most hazardous drawbacks studying participants over multiple sessions can be the loss of participants over time. This study attempts to illuminate the problem of attrition in longitudinal research by estimating the mean effect sizes for participant loss across 57 studies published in 13 prestigious journals which regularly use older participants. Results estimate overall attrition to be around 34% of the original sample. The subsequent break down of attrition into its subtypes yield mean effect sizes for attrition due to Refusal (8%), Loss of contact (10%), Illness (6%), and Death (14%) in studies sampling from adults 50 years or older. Analyses were then conducted via meta-analytic one-way ANOVA and weighted regression to identify possible moderators of overall attrition and their four subtypes.
Date: December 2005
Creator: Rhodes, Anthony Ryan
System: The UNT Digital Library
Rainfall-runoff changes due to urbanization: a comparison of different spatial resolutions for lumped surface water hydrology models using HEC-HMS. (open access)

Rainfall-runoff changes due to urbanization: a comparison of different spatial resolutions for lumped surface water hydrology models using HEC-HMS.

Hydrologic models were used to examine the effects of land cover change on the flow regime of a watershed located in North-Central Texas. Additionally, the effect of spatial resolution was examined by conducting the simulations using sub-watersheds of different sizes to account for the watershed. Using the Army Corps of Engineers, Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS), two different modeling methods were evaluated at the different sub-watershed resolutions for four rainfall events. Calibration results indicate using the smaller spatial resolutions improves the model results. Different scenarios for land cover change were evaluated for all resolutions using both models. As land cover change increased, the amount of flow from the watershed increased.
Date: December 2005
Creator: Redfearn, Howard Daniel
System: The UNT Digital Library
An evaluation of two performance pay systems on the productivity of employees in a certified public accounting firm. (open access)

An evaluation of two performance pay systems on the productivity of employees in a certified public accounting firm.

This study examined the effects of switching from an incentive pay system solely based on productivity to a scorecard-based incentive pay system. Performance of staff and senior accountants was analyzed across three departments for a two-year baseline and a three-year intervention period. Results showed that percent of charge hour goal remained high during the study. Once the scorecard-based incentive system was implemented, performance on the other line items increased or remained at or above goal levels. Incentive payouts were generally higher under the second incentive plan than under the first for top performers. Possible explanations for data trends, weaknesses of the measures within the scorecard, measure/line item alternatives and implications for future research are also discussed.
Date: December 2005
Creator: Shelton, Bryan
System: The UNT Digital Library
"They Don't Make'em Like They Used To": Cultural Hegemony and the Representation of White Masculinity in Recent U.S. Cinema (open access)

"They Don't Make'em Like They Used To": Cultural Hegemony and the Representation of White Masculinity in Recent U.S. Cinema

The purpose of this work is to illuminate how white male hegemony over women and minorities is inscribed through the process of film representation. A critical interrogation of six film texts produced over the last decade yields pertinent examples of how the process of hegemonic negotiation works to maintain power for the ever changing modes of postindustrial masculinity. Through the process of crisis and recuperation the central male characters in these films forge new, more acceptable attributes of masculinity that allow them to retain their centrality in the narrative.
Date: December 2005
Creator: Schneider, Matthew
System: The UNT Digital Library
A Question of Queerness: Case Studies of Contemporary American Television (open access)

A Question of Queerness: Case Studies of Contemporary American Television

This project utilizes a case study approach to explore the various ways in which the portrayals of gay people have changed on American television. Three contemporary programs - Will & Grace, Queer Eye for the Straight Guy and The L Word - are examined as examples of how far American television has progressed in terms of treating gay people with respect. Whether those shows move beyond merely presenting gay characters and into a level of actively challenging mainstream views on gay people is also examined. Findings suggest different factors affect the ability of the individual programs to test said views - including the genres to which each belongs, and their presence on network television (Will & Grace), basic cable (Queer Eye for the Straight Guy) or premium cable (The L Word). While all three programs show some tendencies toward queerness, they also take steps toward negotiating with mainstream culture, indicating that complete queerness may be an unattainable goal on American television.
Date: December 2005
Creator: Bentley, Jon Alexander
System: The UNT Digital Library
The Effects of Rate of Responding on Retention, Endurance, Stability, and Application of Performance on a Match-to-sample Task. (open access)

The Effects of Rate of Responding on Retention, Endurance, Stability, and Application of Performance on a Match-to-sample Task.

Fluent performance has been described as the retention, endurance, stability, and application of the material learned. Fluent performers not only respond quickly during training, they also make many correct responses during training. The current study used a within-subject design to analyze the effects of increased response rates on Retention, Endurance, Stability, and Application tests. Number of correct responses and number of unprompted, correct responses in error correction procedures were yoked for individual participants across an Accuracy-plus-Rate training condition and an Accuracy-Only training condition. One participant scored better in tests that followed the Accuracy-Only condition. One participant showed results that slightly favor the Accuracy-plus-Rate training condition. The two participants whose response rates were successfully reduced in the Accuracy-Only condition performed better on all tests that followed the Accuracy-plus-Rate condition.
Date: December 2005
Creator: Wheetley, Brook
System: The UNT Digital Library
Indoor Propagation Modeling at 2.4 GHz for IEEE 802.11 Networks (open access)

Indoor Propagation Modeling at 2.4 GHz for IEEE 802.11 Networks

Indoor use of wireless systems poses one of the biggest design challenges. It is difficult to predict the propagation of a radio frequency wave in an indoor environment. To assist in deploying the above systems, characterization of the indoor radio propagation channel is essential. The contributions of this work are two-folds. First, in order to build a model, extensive field strength measurements are carried out inside two different buildings. Then, path loss exponents from log-distance path loss model and standard deviations from log-normal shadowing, which statistically describe the path loss models for a different transmitter receiver separations and scenarios, are determined. The purpose of this study is to characterize the indoor channel for 802.11 wireless local area networks at 2.4 GHz frequency. This thesis presents a channel model based on measurements conducted in commonly found scenarios in buildings. These scenarios include closed corridor, open corridor, classroom, and computer lab. Path loss equations are determined using log-distance path loss model and log-normal shadowing. The chi-square test statistic values for each access point are calculated to prove that the observed fading is a normal distribution at 5% significance level. Finally, the propagation models from the two buildings are compared to validate the …
Date: December 2005
Creator: Tummala, Dinesh
System: The UNT Digital Library
Analysis of the One-Horned Rhinoceros (Rhinoceros Unicornis) Habitat in the Royal Chitwan National Park, Nepal. (open access)

Analysis of the One-Horned Rhinoceros (Rhinoceros Unicornis) Habitat in the Royal Chitwan National Park, Nepal.

This study analyzes the remaining suitable habitat of the one-horned rhinoceros, Rhinoceros unicornis, in Royal Chitwan National Park of Nepal. An April 2003 Landsat image was classified into eight land cover types: wetland, sand, water, mixed forest, sal forest, agriculture, settlement, and grassland. This image was converted into habitat suitability maps using cover, food, and water. The rhinoceros prefers grassland habitat with oxbow lakes and closed canopy during the monsoon season. Nominal values of five parameters were used to create a map of habitat suitability index. The map was categorized into four habitat classes: highly unsuitable, unsuitable, moderately suitable habitat, and suitable. Landscape metrics, patch metrics and class metrics associated with habitat were determined through the use of FRAGSTATS.
Date: December 2005
Creator: Thapa, Vivek
System: The UNT Digital Library