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Question of Honor (open access)

Question of Honor

My thesis, Question of Honor, addresses the premise of women's lack of choice in relation to men's honor, and vengeance; concepts that are closely connected to the oppressive world of women in Pakistan. These works deal with concepts of purity and minor transgressions that have an impact on the lives of women in relation to family names and the associative feelings of humiliation linked to men. The subtle nuances of women and their reactions to oppression give a strong emotive content to the work.
Date: May 2004
Creator: Agha, Anila Quayyum
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Baeyer-Villiger Oxidation of 1,7- & 1,9-dibromopentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione

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Baeyer-Villiger oxidation of 1,9-dibromopentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione (1,9-dibromo-PCU-8,11-dione) was performed by using an excess amount of m-chloroperbenzoic acid (3 equivalents) and resulted in the formation of the corresponding monolactone. The reaction would not proceed to the dilactone stage. The structure of the reaction product was established unequivocally via single crystal X-ray diffraction. Baeyer-Villiger oxidation of 1,9-dibromo-PCU-8,11-dione using ceric ammonium nitrate (CAN) was also performed and afforded a mixture of lactones. Only one of these lactones, which also contained an alkene functionality, could be isolated and characterized. 1,7-dibromo-PCU-8,11-dione was also reacted with CAN, yielding the mono-lactone, which has also been characterized.
Date: May 2004
Creator: Akinola, Adeniyi O.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

The Effect of Information Literacy Instruction on Library Anxiety Among International Students

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This study explored what effect information literacy instruction (ILI) may have on both a generalized anxiety state and library anxiety specifically. The population studied was international students using resources in a community college. Library anxiety among international students begins with certain barriers that cause anxiety (i.e., language/communication barriers, adjusting to a new education/library system and general cultural adjustments). Library Anxiety is common among college students and is characterized by feelings of negative emotions including, ruminations, tension, fear and mental disorganization (Jiao & Onwuegbuzie, 1999a). This often occurs when a student contemplates conducting research in a library and is due to any number of perceived inabilities about using the library. In order for students to become successful in their information seeking behavior this anxiety needs to be reduced. The study used two groups of international students enrolled in the English for Speakers of other Languages (ESOL) program taking credit courses. Each student completed Bostick's Library Anxiety Scale (LAS) and Spielberger's State-Trait Anxiety Inventory (STAI) to assess anxiety level before and after treatment. Subjects were given a research assignment that required them to use library resources. Treatment: Group 1 (experimental group) attended several library instruction classes (the instruction used Kuhltau's information search …
Date: May 2004
Creator: Battle, Joel C.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Wayfinding tools in public library buildings: A multiple case study.

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Wayfinding is the process of using one or more tools to move from one location to another in order to accomplish a task or to achieve a goal. This qualitative study explores the process of wayfinding as it applies to locating information in a public library. A group of volunteers were asked to find a selection of items in three types of libraries-traditional, contemporary, and modern. The retrieval process was timed and the reactions of the volunteers were recorded, documented, and analyzed. The impact of various wayfinding tools-architecture, layout, color, signage, computer support, collection organization-on the retrieval process was also identified. The study revealed that many of the wayfinding tools currently available in libraries do not facilitate item retrieval. Inconsistencies, ambiguities, obstructions, disparities, and operational deficiencies all contributed to end-user frustration and retrieval failure. The study suggests that failing to address these issues may prompt library patrons-end users who are increasingly interested in finding information with minimal expenditures of time and effort-may turn to other information-retrieval strategies and abandon a system that they find confusing and frustrating.
Date: May 2004
Creator: Beecher, Ann B.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
An Empirical Investigation of Portfolios with Little Idiosyncratic Risk (open access)

An Empirical Investigation of Portfolios with Little Idiosyncratic Risk

The objective of this study is to answer the following research question: How large is a diversified portfolio? Although previous work is abundant, very little progress has been made in answering this question since the seminal work of Evans and Archer (1968). This study proposes two approaches to address the research question. The first approach is to measure the rate of risk reduction as diversification increases. For the first approach, I identify two kinds of risks: (1) risk that portfolio returns vary across time (Evans and Archer (1968), and Campbell et al. (2001)); and (2) risk that returns vary across portfolios of the same size (Elton and Gruber (1977), and O'Neil (1997)). I show that the times series risk reaches an asymptote as portfolio size increases. Cross sectional risk, on the other hand, does not appears to reach an asymptote as portfolio size increases. The second approach consists of comparing portfolios' performance to a benchmark portfolio that is assumed to be diversified (Statman (1987)). I develop a performance index. The performance index is calculated, for any given test portfolio, as the ratio of the Sharpe-like measure of the test portfolio to the Sharpe-like measure of the benchmark portfolio that is …
Date: May 2004
Creator: Benjelloun, Hicham
Object Type: Thesis or Dissertation
System: The UNT Digital Library
The Effects of Rate Contingent Consequences and Charting on Response Rates for Two Children with Autism. (open access)

The Effects of Rate Contingent Consequences and Charting on Response Rates for Two Children with Autism.

This study investigated the effects of a precision teaching package on response rates of children with autism. Prior to both experiments a preference assessment was conducted to identify high preference activities for each participant. Experiment 1 investigated whether response rates would shift as a function of rate-contingent consequences during an academic task. Different activities were associated with different rates of responding. The experimental package of 1 minute timings, rate contingent consequences, and charting was successful in increasing the rates of responding when the most highly preferred activity was associated with high rates of responding. When the contingencies were switched and the most highly preferred activity was contingent on lower rates of responding, the participant's responding did not decrease. Experiment 2 was an attempt to replicate the results of Experiment 1 using a multiple baseline across tasks. The experimental package was not successful in increasing the rate of responding.
Date: May 2004
Creator: Berman, Christine M.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Hopfield Networks as an Error Correcting Technique for Speech Recognition

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I experimented with Hopfield networks in the context of a voice-based, query-answering system. Hopfield networks are used to store and retrieve patterns. I used this technique to store queries represented as natural language sentences and I evaluated the accuracy of the technique for error correction in a spoken question-answering dialog between a computer and a user. I show that the use of an auto-associative Hopfield network helps make the speech recognition system more fault tolerant. I also looked at the available encoding schemes to convert a natural language sentence into a pattern of zeroes and ones that can be stored in the Hopfield network reliably, and I suggest scalable data representations which allow storing a large number of queries.
Date: May 2004
Creator: Bireddy, Chakradhar
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Clockwork Plums (open access)

Clockwork Plums

Based on a story by Joshua Forehand with additional lyrics by Joshua Bradford, Clockwork Plums is an original musical work that integrates techniques and ideas from composers and different cultures. The accompanying essay about the work includes a summary of the story, "Clockwork Plums," some historical background covering 30 years of pop music, an analysis focusing on the use of African and Reichian compositional devices, and discussion about controlled improvisation and use of the voice as compositional tools. The music consists of three sections scored for 5 voices (lead male vocalist and SATB), flute (doubling tenor saxophone), Bb clarinet (doubling baritone saxophone), violin, cello, piano, electronic keyboard, electric guitar, electric bass, drum set, and percussion.
Date: May 2004
Creator: Bradford, Joshua
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Analysis of Leadership Perceptions Using Multirater Feedback. (open access)

Analysis of Leadership Perceptions Using Multirater Feedback.

Performance improvement intervention begins with assessment. How that assessment is interpreted can mean the difference between success and failure. Previous research of 360-degree feedback instruments has tried to reconcile the differences between multiple rater groups. Rather than searching for agreement, this research proposes to understand the meaning of the differences using multirater feedback. Individuals determine ratings based upon their own perspective and building upon the understanding of rater perspective may result in improved assessments. Data from an existing data set was processed using a second-order CFA in structural equation modeling. Covariance between the second-order factors and rater groups determined the difference in how each rater group perceived the leader.
Date: May 2004
Creator: Bradley, Thomas P.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

City of Denton Municipal Solid Waste Characterization and Management Strategies

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Due to concern about diminishing landfill space, the City of Denton contracted a municipal solid waste characterization study in 1999 that would identify materials for diversion. This paper describes the results of 5 1-week waste sorting events, a scale-house analysis, a recycling participation study, a recycler profile and a similar city study. The results of the characterization studies suggest that at least 50% of each waste stream is recyclable or divertible though paper products accounted for no more than 45% by weight of any waste stream. Curbside recycling participation rate was 71% during the 6-week study period though the average weekly set-out rate was 37%. Recycling participation rates varied significantly by zip code and by home value categories but not by gender. Denton is fairly progressive in its waste management approach when compared to demographically similar cities on a 15-question assessment though recommendations for improvement have been identified.
Date: May 2004
Creator: Brady, Patricia D.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

The Effect of Breastfeeding Education on Breastfeeding Initiation Rates Among Teenage Mothers

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The purpose of this study was to examine the effect of a breastfeeding education program on breastfeeding initiation rates, breastfeeding knowledge, and attitude towards breastfeeding among teenage mothers at an urban school for pregnant and parenting teens. Breastfeeding initiation rose from 35.7% in the control group to 85.2% in the treatment group. The mean score on the Breastfeeding Knowledge Subscale was significantly higher for the treatment group but not the control group. There was not a significant increase in mean scores on the Breastfeeding Attitude Subscale. Participants who initiated breastfeeding scored also had a significant increase in scores from pretest to posttest on the Breastfeeding Knowledge Subscale, while participants who did not initiate breastfeeding did not.
Date: May 2004
Creator: Brown, Amber L.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Utilization of Corridor Habitat by White-tailed Deer (Odocoileus virginianus) in Denton County, Texas

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White-tailed deer (Odocoileus virginianus) (N=15) movements were determined with use of radio telemetry techniques to determine the utilization of corridor habitat on the Lake Ray Roberts Greenbelt Corridor (RRGC) in north central Texas. Home ranges were calculated using three estimation types. Male white-tailed deer tend to have home ranges twice that of female home ranges. Seasonal home ranges were largest during spring (Feb. - April) and fall (Aug. - Oct.) seasons. Males had greater seasonal variation in utilization than females. No statistically significant difference (p=0.24) between white-tailed deer locations when the RRGC experiences heavy human traffic compared to days when there is light human traffic. Linearity indices indicated home ranges less linear than expected (LI = 3.02). The RRGC should be maintained at its current status to provide a variety of vegetational types and protective cover for white-tailed deer and other wildlife of Denton County.
Date: May 2004
Creator: Bruce, Troy Kenneth
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Maxwell's Equations from Electrostatics and Einstein's Gravitational Field Equation from Newton's Universal Law of Gravitation Using Tensors (open access)

Maxwell's Equations from Electrostatics and Einstein's Gravitational Field Equation from Newton's Universal Law of Gravitation Using Tensors

Maxwell's equations are obtained from Coulomb's Law using special relativity. For the derivation, tensor analysis is used, charge is assumed to be a conserved scalar, the Lorentz force is assumed to be a pure force, and the principle of superposition is assumed to hold. Einstein's gravitational field equation is obtained from Newton's universal law of gravitation. In order to proceed, the principle of least action for gravity is shown to be equivalent to the maximization of proper time along a geodesic. The conservation of energy and momentum is assumed, which, through the use of the Bianchi identity, results in Einstein's field equation.
Date: May 2004
Creator: Burns, Michael E.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Biogeography of Montane Mammals on the Colorado Plateau and Adjacent Regions

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This study identifies the biogeographic factors that structure small mammal communities on mountains of the Colorado Plateau and adjacent regions. Forty six isolated ranges were characterized across a 5-state study area encompassing the Colorado Plateau, including the central high plateaus of Utah and the Basin and Range Province (i.e. the Great Basin and mountains of Arizona and New Mexico). Presence/absence data of 25 montane mammal species were used to explore the interactions between historical and ecological processes affecting local and regional diversity patterns. Multivariate analyses, such as non-metric dimensional scaling, were used to explore factors which influence community composition. Results of these analyses revealed the Colorado River as a significant biogeographic barrier that affects montane mammal community structure. MtDNA cytochrome b sequence variation was analyzed among populations of the long-tailed vole, Microtus longicaudus, sampled from five interior ranges of the Colorado Plateau- Abajo, LaSal, Henry, and Chuska Mts., and Boulder Mountain of the Aquarius Plateau-and analyzed using traditional phylogenetic approaches (parsimony and likelihood) as well as nested clade analysis. Results support previous documentation of a major east-west phylogeographic break occurring between populations southeast of the Colorado River (eastern Arizona, Colorado, Wyoming and New Mexico) and all other western populations, which …
Date: May 2004
Creator: Carr, Carla B.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Transfer of Mand Topographies to Tact Relations and Vice Versa in Two Vocal-Verbal Children with Autism (open access)

Transfer of Mand Topographies to Tact Relations and Vice Versa in Two Vocal-Verbal Children with Autism

Skinner (1957) suggested that verbal responses learned as mands are not necessarily emitted in tact relations and vice versa. Previous empirical research has found that newly acquired mands and tacts can be functionally independent. The present study investigated 1) whether novel responses taught in mand relations would be emitted as tacts when opportunity for tacting was presented; 2) whether novel responses taught in tact relations would be emitted as mands when opportunity for manding was presented; and 3) whether the size of pre-experimental mand and tact repertoires affected the rate of acquisition and/or transfer. Two vocal-verbal children with autism were taught three novel responses as mands and three other responses as tacts. Mand topographies transferred to tact relations and tact topographies transferred to mand relations for both participants. Overall acquisition as well as transfer of mands and tacts was faster for the participant with an entering repertoire of approximately 175 mands and 175 tacts than for the participant with a repertoire of approximately 100 mands and 100 tacts.
Date: May 2004
Creator: Castellani, Jill E.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
The Concept of Collision Strength and Its Applications (open access)

The Concept of Collision Strength and Its Applications

Collision strength, the measure of strength for a binary collision, hasn't been defined clearly. In practice, many physical arguments have been employed for the purpose and taken for granted. A scattering angle has been widely and intensively used as a measure of collision strength in plasma physics for years. The result of this is complication and unnecessary approximation in deriving some of the basic kinetic equations and in calculating some of the basic physical terms. The Boltzmann equation has a five-fold integral collision term that is complicated. Chandrasekhar and Spitzer's approaches to the linear Fokker-Planck coefficients have several approximations. An effective variable-change technique has been developed in this dissertation as an alternative to scattering angle as the measure of collision strength. By introducing the square of the reduced impulse or its equivalencies as a collision strength variable, many plasma calculations have been simplified. The five-fold linear Boltzmann collision integral and linearized Boltzmann collision integral are simplified to three-fold integrals. The arbitrary order linear Fokker-Planck coefficients are calculated and expressed in a uniform expression. The new theory provides a simple and exact method for describing the equilibrium plasma collision rate, and a precise calculation of the equilibrium relaxation time. It generalizes …
Date: May 2004
Creator: Chang, Yongbin
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Social Skills Intervention for Students with Emotional/Behavioral Disorders Aged Six through Twelve Years: A Combination of a Literature-Based Curriculum and Telecommunications

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Researchers have noted that by providing formal and informal social skills training (SST), the school can become a potential optimal setting that fosters the development of social competence in students with behavioral problems. Indeed, learning to get along with people is one of the most important skills that we can teach students. In order to maximize its effectiveness, SST must be motivating and personally relevant enough for students to want to use the skills. In addition, it must provide opportunities for learned skills to be practiced under varying conditions and in as close to natural situations as possible in order to enhance the transfer of training. The purpose of the study was to investigate the social competence of students aged from six to twelve, diagnosed with emotional/behavioral disorders (E/BD) in a public self-contained school setting, and to increase the students' social competence by using a literature-based method that employs multiage grouping, impersonation, and telecommunications. By providing intensive, literature-based training in a multiage classroom, the SST gave students opportunities to practice skills in a natural, real-life environment and, therefore, increased the likelihood of generalizing these skills in other settings. The employment of impersonation and telecommunications also enhanced students' acquisition of social …
Date: May 2004
Creator: Chen, Kaili
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Bioavailability and toxicity of 2,4,6-trinitrotoluene in sediment.

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TNT (2,4,6-trinitrotoluene) is a persistent contaminant at many military installations and poses a threat to aquatic ecosystems. Data from environmental fate and toxicity studies with TNT revealed that sediment toxicity test procedures required modification to accurately assess sediment TNT toxicity. Key modifications included aging TNT-spiked sediments 8-14 d, basing lethal dose on measured sediment concentrations of the molar sum of TNT and its main nitroaromatic (NA) transformation products (SNA), basing sublethal dose on average sediment SNA concentrations obtained from integration of sediment SNA transformation models, avoiding overlying water exchanges, and minimizing toxicity test durations. Solid phase microextraction fibers (SPMEs) were investigated as a biomimetic chemical measure of toxicity and bioavailability. Both organism and SPME concentrations provided measures of lethal dose independent of exposure scenario (TNT-spiked sediment or TNT-spiked water) for Tubifex tubifex. Among all benthic organisms tested (Chironomus tentans, Ceriodaphnia dubia, T. tubifex) and matrixes, median lethal dose (LC50) estimates based on SPME and organism concentrations ranged from 12.6 to 55.3 mmol SNA/ml polyacrylate and 83.4 to 172.3 nmol SNA/g tissue, ww, respectively. For Tubifex, LC50s (95% CI) based on SNA concentrations in sediment and SPMEs were 223 (209-238) nmol SNA/g, dw and 27.8 (26.0-29.8) mmol SNA/ml, respectively. Reproductive effects …
Date: May 2004
Creator: Conder, Jason M.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
A Historical Survey of the Euphonium and Its Future in Non-Traditional Ensembles Together with Three Recitals of Selected Works by Jan Bach, Neal Corwell, Vladimir Cosma, and Others (open access)

A Historical Survey of the Euphonium and Its Future in Non-Traditional Ensembles Together with Three Recitals of Selected Works by Jan Bach, Neal Corwell, Vladimir Cosma, and Others

The euphonium has been a respected member of military bands, brass bands, and civilian concert (wind) bands since its invention in 1843. These bands were very visible to the public, and often performed popular music of the day. Since then, the euphonium has had occasional use in orchestral works, jazz, and in brass chamber groups as well. However, by the middle of the 20th century, its traditional use as an instrument of the wind band resulted in a prevailing attitude of the music world toward the euphonium as an instrument strictly for that purpose. This attitude, along with changing popular tastes in music, has over time caused professional opportunities for euphoniumists to become very limited. This lack of public expose for the instrument has therefore resulted in people outside of wind band experience being unaware of the euphonium's existence. There have been, however, positive signs in the last thirty years that changes are taking place in prevailing attitudes toward the euphonium. The formation of the Tubists Universal Brotherhood Association (renamed the International Tuba Euphonium Association in 2000) as a supportive professional organization, the emergence of the tuba/euphonium ensemble as chamber music, new solo works by major composers, and the use …
Date: May 2004
Creator: Cottrell, Jeffrey S.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Contributions of W. A. Criswell to the Establishment and Development of The Criswell College (open access)

Contributions of W. A. Criswell to the Establishment and Development of The Criswell College

This study researched the role of W. A. Criswell as Chancellor of The Criswell College and his involvement in the areas of development, facilities acquisitions, personnel, and academics. This qualitative historical research was taken from Criswell's personal files from 1968 through 2001. W. A. Criswell gave written approval for this review and publication in November 2001. Included in Criswell's files were primary and secondary sources including copies of letters, board meeting minutes, personal notes, catalogs, newspaper articles, sermons, speeches, and other printed forms of communication. All documents pertaining to Criswell's involvement in these four categories were copied and the documents organized in chronological order, by the decade of the 1970s, the 1980s, and 1990s. Primary sources also included personal interviews and telephone interviews with eyewitnesses who were present at the events described, and board meeting minutes. Secondary sources included newspaper articles, magazine articles, national Christian magazines, and journals. Findings were summarized, evaluated and the following research questions answered (1) What was the purpose for establishing a Christian institution of higher education sponsored by First Baptist Church in Dallas, Texas? (2) What was the rationale for establishing a Christian institution of higher education in an area where a high density of …
Date: May 2004
Creator: Cowan, Gloria
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Combat Posttraumatic Stress Disorder: Effect of Intelligence on Symptomatology (open access)

Combat Posttraumatic Stress Disorder: Effect of Intelligence on Symptomatology

The objective of this study was to examine the relations between Posttraumatic Stress Disorder symptomatology and intelligence. Thirty American combat veterans of the Vietnam War, diagnosed with chronic PTSD, were given a psychodiagnostic structured interview. Participants were assessed for Intelligence Quotient as well as the veracity of their self report. The study found that there were significant differences in how participants experienced their PTSD symptoms that were correlated with intelligence. The higher IQ participants reported more frequent and intense guilt related symptoms as well as more intense intrusive recollections. The lower IQ participants experienced more frequent startle responses, more intense problems related to falling or remaining asleep and more frequent affective symptoms related to emotional numbing. Psychologists could use these differences in how PTSD is experienced in treatment planning. It may be useful for therapy to address sleep disturbances and affective numbing in lower IQ individuals. Therapy for higher IQ individuals may be more useful if it addresses feelings of guilt and intrusive recollections.
Date: May 2004
Creator: Crisp, William A.
Object Type: Thesis or Dissertation
System: The UNT Digital Library

An investigation of success metrics for the design of e-commerce Web sites.

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The majority of Web site design literature mainly concentrates on the technical and functional aspects of Web site design. There is a definite lack of literature, in the IS field, that concentrates on the visual and aesthetic aspects of Web design. Preliminary research into the relationship between visual design and successful electronic commerce Web sites was conducted. The emphasis of this research was to answer the following three questions. What role do visual design elements play in the success of electronic commerce Web sites? What role do visual design principles play in the success of electronic commerce Web sites? What role do the typographic variables of visual design play in the success of electronic commerce Web sites? Forty-three undergraduate students enrolled in an introductory level MIS course used a Likert-style survey instrument to evaluate aesthetic aspects of 501 electronic commerce Web pages. The instrument employed a taxonomy of visual design that focused on three dimensions: design elements, design principles, and typography. The data collected were correlated against Internet usage success metrics data provided by Nielsen/NetRatings. Results indicate that 22 of the 135 tested relationships were statistically significant. Positive relationships existed between four different aesthetic dimensions and one single success measure. …
Date: May 2004
Creator: Cutshall, Robert C.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
"Only Connect": A Journey of Teaching Henrik Ibsen's  A Doll House to Play Analysis Students (open access)

"Only Connect": A Journey of Teaching Henrik Ibsen's A Doll House to Play Analysis Students

This work examines the author's experience in teaching A Doll House by Henrik Ibsen to students in the course Play Analysis, THEA 2440, at the University of North Texas in the Fall 2003 and Spring 2004 semesters. Descriptions of the preparations, presentations, student responses, and the author's self-evaluations and observations are included. Included as appendices are a history of Henrik Ibsen to the beginning of his work on A Doll House, a description of Laura Kieler, the young woman on whose life Ibsen based the lead character, and an analysis outline form that the students completed for the play as a requirement for the class.
Date: May 2004
Creator: Davis, Dena Michelle
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Bacterial Cyanide Assimilation: Pterin Cofactor and Enzymatic Requirements for Substrate Oxidation (open access)

Bacterial Cyanide Assimilation: Pterin Cofactor and Enzymatic Requirements for Substrate Oxidation

Utilization of cyanide as the sole nitrogen source by Pseudomonas fluorescens NCIMB 11764 (Pf11764) occurs via oxidative conversion to carbon dioxide and ammonia, the latter satisfying the nitrogen requirement. Substrate attack is initiated oxygenolytically by an enzyme referred to as cyanide oxygenase (CNO), which exhibits properties of a pterin-dependent hydroxylase. The pterin requirement for Pf11764 CNO was satisfied by supplying either the fully (tetrahydro) or partially (dihydro) reduced forms of various pterin compounds at catalytic concentrations (0.5 µM). These compounds included, for example, biopterin, monapterin and neopterin, all of which were also identified in cell extracts. A related CNO-mediated mechanism of cyanide utilization was identified in cyanide-degrading P. putida BCN3. This conclusion was based on (i) the recovery of CO2 and NH3 as enzymatic reaction products, (ii) the dependency of substrate conversion on both O2 and NADH, and (iiii) utilization of cyanide, O2 and NADH in a 1:1:1 reaction stoichiometry. In contrast to findings reported for Pf11764, it was not possible to demonstrate a need for exogenously added pterin as a cofactor for the PpBCN3 enzyme system. However, results which showed that cells of PpBCN3 contained approximately seven times the amount of pterin as Pf11764 (of which a significant portion …
Date: May 2004
Creator: Dolghih, Elena
Object Type: Thesis or Dissertation
System: The UNT Digital Library