UNT Theses and Dissertations - 179 Matching Results

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An Algorithm for the PLA Equivalence Problem

Description: The Programmable Logic Array (PLA) has been widely used in the design of VLSI circuits and systems because of its regularity, flexibility, and simplicity. The equivalence problem is typically to verify that the final description of a circuit is functionally equivalent to its initial description. Verifying the functional equivalence of two descriptions is equivalent to proving their logical equivalence. This problem of pure logic is essential to circuit design. The most widely used technique to solve the problem is based on Binary Decision Diagram or BDD, proposed by Bryant in 1986. Unfortunately, BDD requires too much time and space to represent moderately large circuits for equivalence testing. We design and implement a new algorithm called the Cover-Merge Algorithm for the equivalence problem based on a divide-and-conquer strategy using the concept of cover and a derivational method. We prove that the algorithm is sound and complete. Because of the NP-completeness of the problem, we emphasize simplifications to reduce the search space or to avoid redundant computations. Simplification techniques are incorporated into the algorithm as an essential part to speed up the the derivation process. Two different sets of heuristics are developed for two opposite goals: one for the proof of equivalence and the other for its disproof. Experiments on a large scale of data have shown that big speed-ups can be achieved by prioritizing the heuristics and by choosing the most favorable one at each iteration of the Algorithm. Results are compared with those for BDD on standard benchmark problems as well as on random PLAs to perform an unbiased way of testing algorithms. It has been shown that the Cover-Merge Algorithm outperforms BDD in nearly all problem instances in terms of time and space. The algorithm has demonstrated fairly stabilized and practical performances especially for big PLAs under a wide ...
Date: December 1995
Creator: Moon, Gyo Sik
Partner: UNT Libraries

An Analysis of Factors That Influence the Involvement of Faculty in Learning Communities

Description: This research study attempts to analyze variables that influence the extent of faculty involvement in learning communities. A theoretical framework identifies three primary variable sets—faculty background, structural, and organizational/environmental.
Date: December 1995
Creator: Lapoint, Patricia A. (Patricia Ann)
Partner: UNT Libraries

Assessing regional gully erosion risk: a remote sensing and geographic information systems approach

Description: Gully erosion has been established as a major source of sediment pollution in the upper Trinity River watershed in north-central Texas. This fact, along with a lack of models appropriate for a large-area gully erosion analysis established a need for a gully erosion study in the upper Trinity basin. This thesis project attempted to address this need by deriving an index indicative of gully erosion risk using remote sensing and geographic information systems (GIS) methodology.
Date: August 1995
Creator: Sill, Paul E. (Paul Eric)
Partner: UNT Libraries

An Assessment of Learning Outcomes of Students Taught a Competency-Based Computer Course in an Electronically-Expanded Classroom

Description: This study sought to determine whether there was a difference in subject matter knowledge as measured by a pretest and posttest, a difference in final course grade as a numeric score, and a difference in attitudes toward computers between students in a competency-based ("hands-on") computer applications course taught in an electronically-expanded classroom compared to students taught in a traditional classroom setting. In addition, students taught in the electronically-expanded classroom completed a questionnaire assessing attitudes toward the presentation method. Another purpose of this study was to evaluate the feasibility of applying distance education techniques to teach what was, in essence, an on-campus course. The vehicle for this investigation was an electronically-expanded classroom. The electronically-expanded classroom utilized distance education technology (video, audio, and computer networking) to connect two classrooms in the one building. Students in these two classrooms were the treatment group. Students taking the course in a traditional setting functioned as the comparison group. A total of 109 participants completed the study. Results of the study revealed no significant difference in scores on the subject matter posttest, the final course grade as a numeric score, and attitudes towards computers posttest between students taught the course in an electronically-expanded classroom and students taught the course in the traditional classroom. Results of the survey to measure satisfaction with the presentation method revealed that students in the receive room were slightly more satisfied than students in the send room with the presentation method, but the difference was not significant. The survey indicated that participants in the study were sensitive to technical problems, especially audio-related difficulties. While participants noted some dissatisfaction with audio quality, it had no apparent effect on learning outcomes and attitudes for this study. The study concluded that students taking a course in an electronically-expanded classroom have learning outcomes and attitudes toward ...
Date: December 1995
Creator: Mortensen, Mark H.
Partner: UNT Libraries

Attention and Information Processing Variables in Hypothetically Psychosis-Prone College Students

Description: Considering the explanations of schizophrenia that presume schizophrenia spectrum disorders (e.g., schizotypal personality disorder, schizoaffective disorder, etc.) to be genetically related to schizophrenia, the purpose of this study was to investigate the attention and information processing abilities of individuals who have been identified as schizotypal or psychosis-prone (i.e., schizophrenia spectrum functioning in individuals who do not have schizophrenia). Research indicates that persons identified as psychosis-prone may show attention and information processing deficits similar to individuals with schizophrenia. The identification and description of individuals who later decompensate into schizophrenia would advance the understanding of schizophrenia and its causes. The Chapman's PER-MAG scale (Perceptual Aberration-Magical Ideation) was used to identify 35 hypothetically psychosis-prone college students (schizotypy group) and 42 normal college students (nonschizotypy group) out of the 806 volunteer subjects. Their attention and information processing abilities were measured by COGLAB (a multiparadigmatic cognitive test battery that represents a continuum of cognitive functions, from preattentional to attentional, to conceptual). Their social adjustment was measured by the Premorbid Adjustment Scale (PAS). The hypotheses of the study were that the hypothetically psychosis-prone subjects would perform poorer than controls on COGLAB measures and that COGLAB measures of a more molar nature would better predict social adjustment than would the more molecular tasks. The results of the study did not support the hypotheses as there were no significant differences between the schizotypy group and the nonschizotypy group and the measures of a more molar nature did not better predict social adjustment. Further research might consider increasing the sample size, applying more stringent cut-off criteria for the schizotypy group, and verifying the validity of using PER-MAG, COGLAB, and PAS with this population. Further research also needs to clarify the ways in which those identified as psychosis-prone process information like (or unlike) nonschizotypes and how their current social functioning ...
Date: December 1995
Creator: Ottesen, James McBride
Partner: UNT Libraries

Benjamin West's St. Paul shaking the viper from his hand after the shipwreck: altarpiece of 1789 and designs for other decorative works in the chapel of St. Peter and St. Paul, The Royal Naval College, London

Description: This thesis analyzes Benjamin West's altarpiece St. Paul Shaking the Viper from His Hand After the Shipwreck and his designs for thirty-three related artworks in the Royal Naval College Chapel, Greenwich, England, as a synthesis of the major influences in his life and as an example of both traditional and innovative themes in his artistic style of the late eighteenth century.
Date: December 1995
Creator: Hanna, Margaret A. (Margaret Ann)
Partner: UNT Libraries

Biodegradation of Certain Petroleum Product Contaminants in Soil and Water By Selected Bacteria

Description: Soil contamination by gasoline underground storage tanks is a critical environmental problem. The results herein show that in situ bioremediation using indigenous soil microorganisms is the method of choice. Five sites were selected for bioremediation based on the levels of benzene, toluene, ethylbenzene and xylene and the amount of total petroleum hydrocarbons in the soil. Bacteria capable of degrading these contaminants were selected from the contaminated sites and grown in 1,200 I mass cultures. These were added to the soil together with nutrients, water and air via PVC pipes.
Date: December 1995
Creator: Nevárez-Moorillón, Guadalupe Virginia
Partner: UNT Libraries

Biological and Toxicological Responses Resulting from Dechlorination of a Major Municipal Wastewater Treatment Plant Discharge to the Trinity River

Description: Federal regulations such as the Clean Water Act (P.L. 92-500), and its amendments, direct the Environment Protection Agency (EPA) to implement programs to control the releases of conventional pollutants and toxics into the waterways of the United States. The EPA began requiring treatment plants to conduct toxicity tests (biomonitoring) of their effluent discharges. To control toxicity caused by chlorination of wastewater discharges, the EPA also began requiring some treatment facilities to dechlorinate their wastewater before discharging. This research was funded by the EPA to document the changes that occurred in the Trinity River from the dechlorination of the effluent from Ft. Worth's Village Creek municipal wastewater treatment plant. The study occurred over a two year period beginning in August 1990. A wide variety of biological field assessments and toxicological assays were used to measure various responses. Seven river stations, covering approximately twenty river miles, and the treatment plant effluent were assessed. Two of the river stations were upstream from the treatment plant and used as reference sites. The remaining five river stations were downstream from the treatment plant, spread out over seventeen river miles. The study evaluated the impact of chlorination prior to dechlorination, which served as a baseline. Responses determined during dechlorination were compared to the baseline data. An overall improvement in species richness and diversity was seen at those river stations which had previously been adversely impacted by chlorine. Aquatic toxicity tests, such as those required to be used by dischargers, were conducted during this study. Periodic toxicity was observed with these tests in the effluent and river samples after dechlorination was initiated. Those tests, along with in situ toxicity assays, proved to be good predictors of biological community responses.
Date: August 1995
Creator: Guinn, Richard J. (Richard Joe)
Partner: UNT Libraries

Biopsychosocial Factors Related to Health among Older Women

Description: Older adults are more vulnerable to the ill effects of life stress due to physiological changes associated with aging that result in decreased immunocompetence. Stressors interacting with an aging immune system may produce further declines in health. Variables shown to modulate the effect of stressors on neuroendocrine and immune function and health include social support, personality, coping style, and health locus of control. A comprehensive model is proposed that includes: life stressors, social resources, psychological resources, interaction between stressors and social resources, neuroendocrine and immune function, and symptomatology. This model was evaluated using structured equation modeling. Participants were 97 active, community dwelling, older women, ranging in age from 60 to 93 years.
Date: August 1995
Creator: Carter, Alice Powers
Partner: UNT Libraries

Brain topography of leadership: neurophysiological correlates of the leadership opinion questionnaire

Description: Laboratory research was performed to understand leadership by attempting to link EEG baseline frequency patterns with data from the Leadership Opinion Questionnaire (LOQ) assessment survey. Research began with 293 right-handed males, 18-26 years old, who completed the LOQ. Based on their scores, 61 subjects grouped by the Ohio State Leadership Quadrants, were tested using brain-mapping technology.
Date: December 1995
Creator: Dukes, David Jefferson
Partner: UNT Libraries

Bureaucracy and the Mexican American Elderly: Utilization of Formal and Informal Social Services

Description: Using the National Survey of Hispanic Elderly People, 1988, this study examines the support system of the Mexican American elderly and their utilization of formal social services. Two major research questions were addressed: 1) How does the Mexican American family provide assistance to their elderly family members? and 2) How does the bureaucratic structure affect the Mexican American elderly's access and utilization of formal social services?
Date: December 1995
Creator: Dietz, Tracy L. (Tracy Lynn)
Partner: UNT Libraries

A Causal Model of Parenting Distress: Children with Attention-Deficit Hyperactivity Disorder

Description: The purpose of this study was to functionally define and empirically test a model of psychological distress for mothers of children diagnosed with Attention-Deficit Hyperactivity Disorder (ADHD). This model delineates characteristics of the child, the parent, and the environment that may affect mothers' psychological symptomatology.
Date: August 1995
Creator: Vitanza, Stephanie A. (Stephanie Andrea)
Partner: UNT Libraries

Cell-Free Recovery and Isotopic Identification of Cyanide Degrading Enzymes from Pseudomonas Fluorescens

Description: Cell-free extracts from Pseudomonas fluorescens NCIMB 11764 catalyzed the degradation of cyanide into products that included C02, formic acid, formamide and ammonia. Cyanide-degrading activity was localized to cytosolic cell fractions and was observed at substrate concentrations as high as 100 mM. Two cyanide degrading activities were identified by: (i) the determination of reaction products stoichiometries, (ii) requirements for NADH and oxygen, and (iii) kinetic analysis. The first activity produced CO2 and NH3 as reaction products, was dependent on oxygen and NADH for activity, and displayed an apparent Km for cyanide of 1.2 mM. The second activity generated formic acid (and NH3) pfus formamide as reaction products, was oxygen independent, and had an apparent Km of 12 mM for cyanide. The first enzymatic activity was identified as cyanide oxygenase whereas the second activity consists of two enzymes, a cyanide nitrilase (dihydratase) and putative cyanide hydratase. In addition to these enzymes, cyanide-grown cells were also induced for formate dehydrogenase (FDH), providing a means of recycling NADH utilized by cyanide oxygenase.
Date: December 1995
Creator: Wang, Chien-Sao
Partner: UNT Libraries

Characterization of Tolerance and Cross-tolerance between Noncompetitive N-methyl-D-aspartate (NMDA) Antagonists in Rats Trained to Self-administer Ketamine

Description: Ketamine and phencyclidine (PCP) are noncompetitive antagonists of the N-methyl-D-aspartate (NMDA) type of ligand-gated glutamate receptors. Both agents have high abuse liability, and may produce dependence. Tolerance to the reinforcing effects of drugs of abuse is widely regarded as a key component of the dependence process. Therefore, the present study was conducted to examine whether tolerance develops to the reinforcing effects of ketamine, and whether PCP and dizocilpine, a noncompetitive NMDA antagonist with negligible abuse liability, produce cross-tolerance to the reinforcing effects of ketamine. Further, identification of the neural mechanisms that underlie tolerance to the reinforcing effects of drugs may yield information regarding drug dependence.
Date: December 1995
Creator: Ward, Amie S. (Amie Sue)
Partner: UNT Libraries

Chronically Ill Children: Maternal Stress and Psychological Symptomatology

Description: This study used a parenting stress and coping model to identify predictors of symptomatology for 13 8 mothers of medically compromised children. This model proposed that: child characteristics (severity of the chronic illness and child related parenting stressors); parent characteristics (self-esteem, sense of competence, and parents' perceived stress/distress); and environmental characteristics (social support, general life stressor events, and demographic variables) contribute to psychological symptomatology for these mothers. Multiple regression analysis found a relationship between general life stressor events, severity of the children's chronic conditions, lower satisfaction with social support, lower self-esteem, and younger mothers' ages and greater symptomatology. Trends toward significance were found for more parenting stress and lower parenting sense of competence predicting greater symptomatology. Predicted relationships between family socioeconomic status and parenting daily hassles and symptomatology were not supported.
Date: August 1995
Creator: Driskill, Gail
Partner: UNT Libraries

College Students at Risk of Academic Failure: Neurocognitive Strengths and Weaknesses

Description: This study examined the neurocognitive skills, incidence of mild head injury, incidence of learning disabilities, and study habits among college students with grade point average of 2.00 or below (N = 25) as contrasted with college students with grade point average above 2.00 (N = 70). The intent of this research was to extend the work of Segalowitz and Brown (1991) and Segalowitz and Lawson (1993) who found significant associations between reported history of mild head injury and developmental disabilities among high school and college samples. MANOVAs conducted on measures of academic achievement, global cognitive skills, verbal and nonverbal memory, motor and tactile functioning, and study habits did not discriminate between probationary and non-probationary students. Probationary and non-probationary students also did not differ with regard to incidence of reported head injury, frequency of diagnosed learning disabilities, and study habits. Measures of neurocognitive functioning and study habits did not contribute to the prediction of grade point average over and above that predicted by Scholastic Aptitude Test composite score. Several exploratory analyses were performed examining the relationship between study habits and neurocognitive skills. Gender differences, implications for future research and development of study skills courses, and limitations of this study were discussed.
Date: December 1995
Creator: Saine, Kathleen C. (Kathleen Chen)
Partner: UNT Libraries

Combined Electrochemistry and Spectroscopy of Complexes and Supramolecules containing Bipyridyl and Other Azabiphenyl Building Blocks

Description: A group of azabiphenyl complexes and supramolecules, and their reduced and oxidized forms when possible, were characterized by cyclic voltammetry and electronic absorption spectroscopy. The oxidized and reduced species, if sufficiently stable, were further generated electrochemically inside a specially designed quartz cell with optically transparent electrode, so that the spectra of the electrochemically generated species could be taken in situ. Assignments were proposed for both parent and product electronic spectra. Species investigated included a range of Ru(II) and Pt(II) complexes, as well as catenanes and their comparents. Using the localized electronic model, the electrochemical reduction can be in most cases assigned as azabiphenyl-based, and the oxidation as transition metal-based. This is consistent with the fact that the azabiphenyl compounds have a low lying π* orbital. The electronic absorption spectra of the compounds under study are mainly composed of π —> π* bands with, in some cases, charge transfer bands also.
Date: August 1995
Creator: Yang, Lei
Partner: UNT Libraries

A Comparative Analysis of the Effects of Video-Based versus Live Presentation Staff Development on Teachers' Cognitive Learning and Attitudes

Description: The problem of this study was the identification of effective and efficient means of providing quality staff development for reading instruction within a school-district setting. The study investigated the comparative effectiveness of two staff development delivery systems measured by 1) a cognitive test of a school district's reading program and 2) an affective measure of teacher attitudes toward staff development. The sample was drawn from the teacher population of a large urban school district. The 46 subjects were elementary school teachers in grades K-5 randomly divided into two groups: Group A (videotape with a trained on-site facilitator) and Group B (face-to-face live presenter). Participants in the study received training using "The Fort Worth Reading Program," a staff development program designed by the researcher. In addition to the presentation of content information, which is the central component, the program features small group discussions, off-line activities, and question and answer periods. Both groups received the same treatment with the following exception. A central component to the Group A training was the presentation of content information in a videotape format. Group B did not view the videotape, but received the same information via live presenter. Two instruments developed by the researcher were used in the study: 1) The Teacher Staff Development Questionnaire, a Likert-type survey to obtain teacher attitudes toward staff development, and 2) The Cognitive Test of Reading Knowledge, an instrument designed to measure cognitive objectives of the district's reading program. A multivariate analysis of covariance revealed no statistically significant differences between the groups. It was concluded that elementary classroom teachers, regardless of their attitudes toward staff development, learn content material equally well with either of the two delivery systems explored in this study. Specific suggestions and recommendations for further studies are addressed and discussed. Examples of the measurement instruments are included.
Date: December 1995
Creator: Cox, Alan R. (Alan Ray)
Partner: UNT Libraries

A Comparison of At-Risk Students Receiving an Academic Support Program with At-Risk Students Receiving no Academic Support Program

Description: The problem of this study was to determine if at-risk students who were enrolled in an educational support class for one hour a day would have an improvement on the four at-risk indicators being measured over students not enrolled in the academic support program. The four at-risk indicators are grade point average, self-concept, days absent from school, and discipline referrals. The hypothesis formulated for this study predicted no significant difference in mean scores of the four measured indicators between groups. These indicators were measured by the Piers-Harris Children's Self-Concept Scale, official school attendance records, official school transcripts, and the school's discipline records book. The at-risk population was identified from the use of an at-risk indicator scale. After random placement into either the control or experimental groups the samples were divided and analyzed according to grade and gender. The study was conducted over a 12 week period and included students from the Memphis, Michigan School District in grades six through nine. Data were analyzed by the independent means t test at the .05 level. The experimental group means were further analyzed for practical significance and for directional improvement. A series of tables provides a comparison of scores for all students participating in the study. For students participating in the experimental group three of the four indicators, self-esteem, days absent from school, and grade point average had a statistically significant difference in mean scores. The majority of mean scores moved in a direction of improvement indicating enrollment in the treatment had a positive influence on the at-risk indicators. Most scores that did not show a statistically significant difference in means did report a high level of practical significance that was a result of being enrolled in the academic support program.
Date: August 1995
Creator: Williams, Glenda Guenther
Partner: UNT Libraries

A Comparison of College Athletes and Nonathletes in the areas of Career Decision-Making. Salience, and Values

Description: This study paralleled Smallman's (1993) analysis of college athletes at an NCAA Division I school, which found significant differences between athletes and nonathletes in readiness to make career decisions. The present study measured career decision-making skills using The Career Development Inventory. In addition, the present study examined the salience of roles (i.e., student, worker, citizen, family member, and leasurite) as measured by The Salience Inventory.
Date: August 1995
Creator: Patterson, Howard Y. (Howard Yates)
Partner: UNT Libraries

A Comparison of Knowledge and Attitudes between Directors of Athletics and Head Trainers in the Southwest and Southland Conferences Regarding HIV-transmission Issues in Athletics

Description: The purpose of this study was to investigate and compare knowledge and attitudes of directors of athletics and head trainers in the Southwest (Division 1A) and the Southland (Division 1AA) Conferences concerning HIV/AIDS issues related to transmission, prevention, and protection within college athletics programs. The results of this qualitative study provided descriptive data from university administrators within the athletics setting who are responsible for providing adequate student athlete health care services from developed and implemented administrative policies that directly or indirectly affect a student athlete's physiological and psychological well-being.
Date: December 1995
Creator: Whiteley, Harold L. (Harold Lee)
Partner: UNT Libraries