UNT Theses and Dissertations - 138 Matching Results

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An Adaptive Linearization Method for a Constraint Satisfaction Problem in Semiconductor Device Design Optimization

Description: The device optimization is a very important element in semiconductor technology advancement. Its objective is to find a design point for a semiconductor device so that the optimized design goal meets all specified constraints. As in other engineering fields, a nonlinear optimizer is often used for design optimization. One major drawback of using a nonlinear optimizer is that it can only partially explore the design space and return a local optimal solution. This dissertation provides an adaptive optimization design methodology to allow the designer to explore the design space and obtain a globally optimal solution. One key element of our method is to quickly compute the set of all feasible solutions, also called the acceptability region. We described a polytope-based representation for the acceptability region and an adaptive linearization technique for device performance model approximation. These efficiency enhancements have enabled significant speed-up in estimating acceptability regions and allow acceptability regions to be estimated for a larger class of device design tasks. Our linearization technique also provides an efficient mechanism to guarantee the global accuracy of the computed acceptability region. To visualize the acceptability region, we study the orthogonal projection of high-dimensional convex polytopes and propose an output sensitive algorithm for projecting polytopes into two dimensions.
Date: May 1999
Creator: Chang, Chih-Hui, 1967-
Partner: UNT Libraries

Comparative Biochemistry and Evolution of Aspartate Transcarbamoylase from Diverse Bacteria

Description: Aspartate transcarbamoylase (ATCase) catalyzes the first committed step in pyrimidine biosynthesis. Bacterial ATCases are divided into three classes, A, B and C. Class A ATCases are largest at 450-500, are. dodecamers and represented by Pseudomonas ATCase. The overlapping pyrBC' genes encode the Pseudomonases ATCase, which is active only as a 480 kDa dodecamer and requires an inactive pyrC'-encoded DHOase for ATCase activity. ATCase has been studied in two non-pathogenic members of Mycobacterium, M. smegmatis and M. phlei. Their ATCases are dodecamers of molecular weight 480 kDa, composed of six PyrB and six PyrC polypeptides. Unlike the Pseudomonas ATCase, the PyrC polypeptide in these mycobacteria encodes an active DHOase. Moreover, the ATCase: DHOase complex in M. smegmatis is active both as the native 480 kDa and as a 390 kDa complex. The latter lacks two PyrC polypeptides yet retains ATCase activity. The ATCase from M. phlei is similar, except that it is active as the native 480 kDa form but also as 450,410 and 380 kDa forms. These complexes lack one, two, and three PyrC polypeptides, respectively. By contrast,.ATCases from pathogenic mycobacteria are active only at 480 kDa. Mycobacterial ATCases contain active DHOases and accordingly. are placed in class A1 . The class A1 ATCases contain active DHOases while class A2 ATCases contain inactive DHOases. ATCase has also been purified from Burkholderia cepacia and from an E. coli strain in which the cloned pyrB of B. cepacia was expressed. The B. cepacia ATCase has a molecular mass of 550 kDa, with two different polypeptides, PyrB (52 kDa) and PyrC of (39 kDa). The enzyme is active both as the native enzyme at 550 kDa and as smaller molecular forms including 240 kDa and 165 kDa. The ATCase synthesized by the cloned pyrB gene has a molecular weight of 165 kDa composed ...
Date: May 1999
Creator: Hooshdaran, Massoumeh Ziba
Partner: UNT Libraries

The Effect of Quality and Color Visual Aids on Immediate Recall, Attitude Toward Speaker, and Attitude Toward Speech

Description: Thirty years of empirical research on visual aids have produced inconsistent results--perhaps because the quality and color of those visuals were inconsistent. The purpose of this study was to determine what effects quality and color of instructional transparencies used in an informative speech have on listener recall and attitudes toward speaker and speech. A total of 709 community college and university students in 36 intact classes were randomly assigned to one of four visual treatment groups (poor-quality black/white, high-quality black/white, poor-quality color, or high-quality color) or one of two control groups (no-speech or no-visuals). A videotaped speech was projected onto a large screen at the right of the room; visual aids (each shown for approximately 30 seconds) were projected onto another screen set immediately to the left. Recall was measured by a 10-item multiple choice test; attitude toward speech and speaker were each measured by six seven-item semantic differential scales. Analysis of variance indicated that the type of transparencies used in an informative speech have a definite effect on immediate recall and attitude toward the speech, but no effect on attitude toward speaker. All four treatment groups scored significantly higher on recall than the no-speech and no-visual control groups. Log percent of change showed poor color to produce the lowest scores (still 13% better than control) and quality color to produce the highest scores (19.5'% better). Analysis found listeners to have a more positive attitude toward the speech when quality color, quality black/white, or poor black/white visuals were used. It appears that any visual (even a poor quality one) produces better recall than no visuals. Speakers with the time to produce quality visuals should add color; speakers who pay little attention to quality would be advised to use black/white visuals. Implications for future research are suggested.
Date: May 1999
Creator: Hamilton, Cheryl A. (Cheryl Ann)
Partner: UNT Libraries

Isolation and Characterization of a New Capsule-Forming Bacterium

Description: A unique, previously undescribed Gram-negative bacterium was isolated from several soils in Texas and extensively characterized in this study. The cells measured 1-2 by 4-6 μm. The distinguishing characteristic of the bacterium is the extraordinary capsular material which surrounds the cells. The new isolates are aerobic, mesophilic, non motile and have the ability to utilize a variety of organic compounds as the sole source of carbon and energy. The organism grows optimally at 30° C and the optimal pH lies between 7.0-8.0. The isolates produce catalase but oxidase is not produced. They do not produce indole or hydrogen sulfide. The organism can hydrolyze gelatin and Tween 80 but not starch, esculin and casein. The major cellular fatty acid is anteiso 15:0. The guanine and cytosine content is 58-62 mole%. The organism's taxonomic position was further established by specific gene probes, 16S rRNA homology, DNA homology and "ribotyping." These data showed that it was most closely related to members of the genus Paenibacillus, although somewhat divergent from other species classified in this genus. After careful evaluation of the results obtained during this study, it is proposed that this unique bacterium be named Paenibacillus velasolus sp. nov.
Date: May 1999
Creator: Thongmee, Acharawan
Partner: UNT Libraries

An Analysis of a Title I Inclusive Middle School Program in Texas over a Three Year Period: A Case Study

Description: The purpose of this study was to describe a Title I inclusion program in a north Texas middle school, to evaluate the degree of its success as a high achieving program, and to analyze how closely it met the requirements of the Improving America's Schools Act of 1994. Data were collected from the learning facilitators and teachers at the middle school with the permission of the school district. This study began with extensive research on the nature of adolescents and the beliefs and characteristics of high achieving middle schools. It addressed the steps which were recommended in the literature to improve middle schools and benefit students that are at-risk of failing to master the curriculum at their grade level. The researcher concluded by reporting effective strategies being used in middle school at-risk programs. These are strategies noted by experts as successful in identified programs. The population for this study was seventh and eighth grade Title I students who attended middle school during the 1992-1993, 1993-1994, 1994-1995 and 1995-1996 school years. The data collected by the researcher are presented in two parts: the description of the Title I inclusion program; and the results of the Texas Assessment of Academic Skills tests in reading and math, the Shaw-Hiehle Math Tests, and the Gates-MacGinitie Reading Tests. Findings from this study suggest that the program met the requirements of a Title I program established by the federal government. The test scores for the middle school improved during the three years of the program. The Title I inclusion program met the requirements of the Improving America's Schools Act. Finally, the Title I students were successful working in classrooms with other students on challenging curriculum which met the State's content and performance standards. These findings have implications for other middle schools who are developing Title I ...
Date: May 1999
Creator: Restivo, Janet DiMaria
Partner: UNT Libraries

Brief Symptom Inventory: Music and Non-Music Students

Description: The present study is a comparison of music and non-music students with respect to their response patterns on the Brief Symptom Inventory as well as several demographic questions. The sample consisted of 148 non-music students and 141 music students at three levels: (1) freshmen/sophomore; (2) juniors/seniors; and (3) graduate students. Music students consisted of volunteers from several different music classes and non-music students were volunteers from non-music classes. There were no significant differences found among or between groups for the BSI subscales. However, music students were significantly less likely to have gone to counseling in the past and to seek professional counseling for future problems. Recommendations for psycho-educational interventions with musicians are discussed as well as suggestions for future research.
Date: August 1999
Creator: Young, James A. (James Alan), 1968-
Partner: UNT Libraries

Biodiversity of Dragonflies and Damselflies (Odonata) of the South-Central Nearctic and Adjacent Neotropical Biotic Provinces

Description: The south-central United States serves as an important biogeographical link and dispersal corridor between Nearctic and Neotropical elements of western hemisphere odonate faunas. Its species are reasonably well known because of substantial collections, but there has been no concerted effort to document the extent of biodiversity and possible geographic affinities of dragonflies and damselflies of this region. The recent discoveries of Argia leonorae Garrison, Gomphus gonzalezi Dunkle and Erpetogomphus heterodon Garrison from southern and western Texas and northern Mexico suggest that Odonata species remain to be discovered in this area, particularly from far south Texas and northern Mexico. I have documented a total of 12,515 records of Odonata found in 408 counties within the south-central U.S. A total of 73 species of damselflies and 160 species of dragonflies was revealed in the region. The 233 (197 in Texas) Odonata species are distributed among 10 families and 66 genera. Illustrated family, generic, and species-level keys are provided. Since the beginning of this work in the Fall of 1993, one species has been added each to the Louisiana and Oklahoma faunas, and 12 species have been added, previously unreported from Texas, including four new to the U.S. The area of highest Odonata biodiversity overall (161 spp.) is in the Austroriparian biotic province. The greatest degree of faunal similarity between the south-central U.S. and other intra-continental regions was observed for the eastern (64%) United States. Diversity is a function of area, and as expected, the numbers of breeding birds and Odonata, in each contiguous U.S. state are positively correlated (r=0.376, n=33, p=0.031). There is, however, no strong correlation between land area and species diversity within the region, but those natural biotic provinces (Austroriparian, Texan, Balconian) where aquatic systems and topographic heterogeneity are the greatest provide a broader spectrum of potential Odonata habitats and ...
Date: May 1999
Creator: Abbott, John C.
Partner: UNT Libraries

Factors Influencing How Students Value Asynchronous Web Based Courses

Description: This dissertation discovered the factors influencing how students value asynchronous Web-based courses through the use of qualitative methods. Data was collected through surveys, observations, interviews, email correspondence, chat room and bulletin board transcripts. Instruments were tested in pilot studies of previous semesters. Factors were identified for two class formats. The asynchronous CD/Internet class format and the synchronous online Web based class format. Also, factors were uncovered for two of the instructional tools used in the course: the WebCT forum and WebCT testing. Factors were grouped accordingly as advantages or disadvantages under major categories. For the asynchronous CD/Internet class format the advantages were Convenience, Flexibility, Learning Enhancement, and Psychology. The disadvantages included Isolation, Learning Environment, and Technology. For the synchronous online Web based class format the advantages were Convenience, Flexibility, Human Interaction, Learning Enhancement and Psychology, whereas the disadvantages included Isolation, Learning Environment and Technology. Concurrently, the study revealed the following factors as advantages of the WebCT Forum: Help Each Other, Interaction, Socialization, Classroom News, and Time Independent. The disadvantages uncovered were Complaints, Technical Problems and Isolation. Finally, advantages specified for the WebCT testing tool were Convenience, Flexibility and Innovations, and its disadvantages were Surroundings Not Conducive to Learning, and Technical Problems. Results indicate that not only classroom preference, learning style and personality type influence how students value a Web based course, but, most importantly, a student's lifestyle (number of personal commitments, how far they live, and life's priorities). The WebCT forum or bulletin board, and the WebCT testing or computerized testing were seen mostly by students, as good tools for encouraging classroom communication and testing because of the convenience and flexibility offered. Still, further research is needed both quantitatively and qualitatively to ascertain the true weight of the factors discovered in this study.
Date: December 1999
Creator: Pérez Cereijo, Maria Victoria
Partner: UNT Libraries

Evolution of Vacancy Supersaturations in MeV Si Implanted Silicon

Description: High-energy Si implantation into silicon creates a net defect distribution that is characterized by an excess of interstitials near the projected range and a simultaneous excess of vacancies closer to the surface. This defect distribution is due to the spatial separation between the distributions of interstitials and vacancies created by the forward momentum transferred from the implanted ion to the lattice atom. This dissertation investigates the evolution of the near-surface vacancy excess in MeV Si-implanted silicon both during implantation and post-implant annealing. Although previous investigations have identified a vacancy excess in MeV-implanted silicon, the investigations presented in this dissertation are unique in that they are designed to correlate the free-vacancy supersaturation with the vacancies in clusters. Free-vacancy (and interstitial) supersaturations were measured with Sb (B) dopant diffusion markers. Vacancies in clusters were profiled by Au labeling; a new technique based on the observation that Au atoms trap in the presence of open-volume defects. The experiments described in this dissertation are also unique in that they were designed to isolate the deep interstitial excess from interacting with the much shallower vacancy excess during post-implant thermal processing.
Date: May 1999
Creator: Venezia, Vincent C.
Partner: UNT Libraries

Structured Child and Parent Groups with ADHD Children: Evaluation of Varying Levels of Parent Involvement

Description: Attention Deficit/Hyperactivity Disorder (ADHD) is one of the most commonly diagnosed disorders of childhood. This study was designed to evaluate the effectiveness of combined parent training and structured group therapy with children diagnosed with ADHD. The study sought to evaluate the amount of parent training needed to lead to significant changes in children and parents. Families were assigned to a wait-list control condition or to one of two parent treatment conditions: a complete parent group or a handout-only group. Children participated in a seven session social skills and behavior management group. The treatments were designed to concurrently enhance skills of both parents and children. Dependent measures assessed change in the following three areas: (1) child symptomatic behaviors, (2) parental attitudes, and (3) parental behaviors. Results showed that the full parent group led to greater levels of improvement in both child behavior problems and parental feelings of stress and control. The full parent group also led to greater consistency in parenting methods. Findings in the study are discussed in the context of the parent-child coercive cycle model.
Date: August 1999
Creator: Driskill, Julie D. (Julie Diane)
Partner: UNT Libraries

The Effects of Brief Exposure to Non Traditional Media Messages on Female Body Image

Description: Body image may be defined as the perception or attitude one has regarding the appearance of his or her body. Body image concerns are not only central to the diagnostic criteria of eating disorders, but also create distress for nonclinical populations. Females (n = 167) from three universities participated in a study by completing the Eating Disorder Inventory - 2 (Garner, 1991) and the Figure Rating Scale (Stunkard, Sorenson, & Schulsinger, 1983); watching a video; and then completing the instruments again. Subjects in the treatment group (n = 89) viewed a video designed to increase awareness of unrealistic body sizes and shapes seen in the media (Kilbourne, 1995). Subjects in the comparison group (n = 77) viewed a video unrelated to female body image.
Date: August 1999
Creator: Garber, Carla F.
Partner: UNT Libraries

The Effects of Organic Surface Amendments on Soil Nutrients and Initial Tree Establishment

Description: This study examined the effects of replicating woodland soil surface horizonation on the nutrient status of underlying soils and the initial establishment and growth of trees. A total of 283 container grown trees were planted in a bufferzone around a future landfill site. Control amendments consisted of an 8 cm layer (0.5 m3) of wood chips applied in a circular area of 4.6 m2 around the trees' planting pit. For the treatment, a 2.5 cm layer of composted biosolids (0.15 m3 or 80 Mg/ha) was applied in a circular area of 4.6 m2 around the trees' planting pit followed by an 8 cm layer (0.5 m3) of wood chips. The results indicate that the replication of woodland soil surface attributes using composted biosolids can significantly improve the nutrient status of underlying soil. Some significant effects were seen under control conditions, too. However, the effects on tree establishment and growth parameters were, for the most part, not statistically significant.
Date: May 1999
Creator: Thuesen, Kevin (Kevin Andrew)
Partner: UNT Libraries

Theological Distance Learning through Trinity College and Theological Seminary: Programs, Problems, Perceptions, and Prospects

Description: An international survey was conducted to assess theological higher education via distance learning as perceived by graduates of Trinity College and Theological Seminary's (Trinity) doctoral programs. The purpose of the study was to determine student-perceived strengths and weaknesses of Trinity's doctoral-level distance education theology programs. Also, the future of distance-learning mediated programs of theological higher education was speculated. A random sample of 400 doctoral recipients was selected from the population of 802 doctoral recipients who graduated from Trinity between the years of 1969 and March 1998. A mailed questionnaire was used to collect data. A total of 203 (50.0%) were returned. Frequency counts, percentage distributions, and chi-square tests of goodness-of-fit were employed to analyze the data. A profile of the modal type of student who would participate in theological distance education at the doctoral level was developed from the demographic variables queried. Responses to questions regarding respondents' educational experiences and coursework were solicited as well. Respondents identified five primary strengths of Trinity's distance education doctoral programs as: the convenience of the program; the immediate application of course content to personal and professional endeavors; the quality of education provided; the Biblical groundedness of the curricula, the materials, and the faculty; and the required reading and research. The three predominant weaknesses of Trinity's distance education doctoral programs as identified by program graduates include: the lack of interaction between students and faculty; the lack of regional accreditation; and course repetitiveness meaning that some courses offered repeated content from prior studies at a lower educational level. It was concluded that the future of theological higher education via distance learning is promising. Trinity has emerged as a dominant distance learning institution as a result of its continued exploration and advancements. However, Trinity and other similar distance education institutions must continually and consistently evaluate their programs ...
Date: August 1999
Creator: Ray, Abby A. (Abby Adams)
Partner: UNT Libraries

Chaucer and the Rhetorical Limits of Exemplary Literature

Description: Though much has been made of Chaucer's saintly characters, relatively little has been made of Chaucer's approach to hagiography. While strictly speaking Chaucer produced only one true saint's life (the Second Nun's Tale), he was repeatedly intrigued and challenged by exemplary literature. The few studies of Chaucer's use of hagiography have tended to claim either his complete orthodoxy as hagiographer, or his outright parody of the genre. My study mediates the orthodoxy/parody split by viewing Chaucer as a serious, but self-conscious, hagiographer, one who experimented with the possibilities of exemplary narrative and explored the rhetorical tensions intrinsic to the genre, namely the tensions between transcendence and imminence, reverence and identification, and epideictic deliberative discourse.
Date: May 1999
Creator: Youmans, Karen DeMent
Partner: UNT Libraries

The Applicability of SERVPERF in Judging Service Quality for Biomedical Information Professionals

Description: The applicability of SERVPERF as a tool for judging the quality of services used by biomedical information professionals was tested using standard statistical procedures. Data was gathered nationally via a combination of electronic and non-electronic forms, from Area Health Education Center (AHEC) information professionals and the results consolidated to provide information for the study. It was determined that SERVPERF was applicable in making judgements about service quality for AHEC information professionals. Their perceptions about service quality tended to have a greater influence than did their level of actual satisfaction on whether or not they planned to use a particular service in the future. There is currently no validated tool available to ascertain the quality of services offered to these valuable members of the rural health care team. This dissertation proposes to provide such a tool, and to serve as a guide or template for other professionals seeking a means to judge service quality in their own disciplines.
Date: May 1999
Creator: Jenkins, Sharon D. (Sharon Dezel)
Partner: UNT Libraries

An Analysis of Status: Women in Texas, 1860-1920

Description: This study examined the status of women in Texas from 1860 to 1920. Age, family structure and composition, occupation, educational level, places of birth, wealth, and geographical persistence are used as the measurements of status. For purposes of analysis, women are grouped according to whether they were married, widowed, divorced, or single.
Date: May 1999
Creator: Breashears, Margaret Herbst
Partner: UNT Libraries

Assessment and Analysis of Per Pupil Expenditures: a Study Testing a Micro-Financial Model in Equity and Student Outcome Determination

Description: The purpose of this study was to examine district level financial data to assess equity across districts, to compare equity benchmarks established in the literature using selected functions from the state's financial database, and to determine the predictive value of those functions to the Texas Assessment of Academic Skills (TAAS) tests of 1997.
Date: May 1999
Creator: Holsomback, James Richard
Partner: UNT Libraries

The Anglo-American Council on Productivity: 1948-1952 British Productivity and the Marshall Plan

Description: The United Kingdom's postwar economic recovery and the usefulness of Marshall Plan aid depended heavily on a rapid increase in exports by the country's manufacturing industries. American aid administrators, however, shocked to discover the British industry's inability to respond to the country's urgent need, insisted on aggressive action to improve productivity. In partial response, a joint venture, called the Anglo-American Council on Productivity (AACP), arranged for sixty-six teams involving nearly one thousand people to visit U.S. factories and bring back productivity improvement ideas. Analyses of team recommendations, and a brief review of the country's industrial history, offer compelling insights into the problems of relative industrial decline. This dissertation attempts to assess the reasons for British industry's inability to respond to the country's economic emergency or to maintain its competitive position faced with the challenge of newer industrializing countries.
Date: May 1999
Creator: Gottwald, Carl H.
Partner: UNT Libraries

Thermodynamic Properties of Nonelectrolyte Solutes in Ternary Solvent Mixtures

Description: The purpose of this dissertation is to investigate the thermodynamic properties of nonelectrolyte solutes dissolved in ternary solvent mixtures, and to develop mathematical expressions for predicting and describing that behavior in the solvent mixtures. Thirty-four ternary solvent systems were studied containing either alcohol (1-propanol, 2-propanol, 1-butanol, and 2-butanol), alkane (cyclohexane, heptane, and 2,2,4-trimethylpentane) or alkoxyalcohol (2-ethoxyethanol and 2-butoxyethanol) cosolvents. Approximately 2500 experimental measurements were performed. Expressions were derived from the Combined Nearly Ideal Multiple Solvent (NIMS)/Redlich-Kister, the Combined Nearly Ideal Multiple Solvent (NIMS)/Bertrand, Acree and Burchfield (BAB) and the Modified Wilson models for predicting solute solubility in ternary solvent (or even higher multicomponent) mixtures based upon the model constants calculated from solubility data in sub-binary solvents. Average percent deviation between predicted and observed values were less than 2%, documenting that these models provide a fairly accurate description of the thermodynamic properties of nonelectrolyte solutions. Moreover, the models can be used for solubility prediction in solvent mixtures in order to find the optimum solvent composition for solubilization or desolubilization of a solute. From a computational standpoint, the Combined Nearly Ideal Multiple Solvent/Redlich-Kister equation is preferred because the needed model constants can be calculated with a simple linear regressional analysis. Model constants for the Modified Wilson equation had to be calculated using a reiterative trial-and-error method. The C++ program for the Modified Wilson equation applied to ternary and heptanary solvent mixtures is attached.
Date: August 1999
Creator: Deng, Tʻai-ho
Partner: UNT Libraries