UNT Libraries - 18,578 Matching Results

Search Results

Functional Characterization of Mtnip/latd’s Biochemical and Biological Function
Symbiotic nitrogen fixation occurs in plants harboring nitrogen-fixing bacteria within the plant tissue. The most widely studied association is between the legumes and rhizobia. In this relationship the plant (legumes) provides the bacteria (rhizobia) with reduced carbon derived from photosynthesis in exchange for reduced atmospheric nitrogen. This allows the plant to survive in soil, which is low in available of nitrogen. Rhizobia infect and enter plant root and reside in organs known as nodules. In the nodules the bacteria fix atmospheric nitrogen. The association between the legume, Medicago truncatula and the bacteria Sinorhizobium meliloti, has been studied in detail. Medicago mutants that have defects in nodulation help us understand the process of nitrogen fixation better. One such mutant is the Mtnip-1. Mtnip-1 plants respond to S. meliloti by producing abnormal nodules in which numerous aberrant infection threads are produced, with very rare rhizobial release into host plant cells. The mutant plant Mtnip-1 has an abnormal defense-like response in root nodules as well as defects in lateral root development. Three alleles of the Mtnip/latd mutants, Mtnip-1, Mtlatd and Mtnip-3 show different degrees of severity in their phenotype. Phylogenetic analysis showed that MtNIP/LATD encodes a protein belonging to the NRT1(PTR) family of nitrate, peptide, dicarboxylate and phytohprmone transporters. Experiments with Mtnip/latd mutants demonstrats a defective nitrate response associated with low (250 μM) external nitrate concentration rather than high (5 mM) nitrate concentration. This suggests that the mutants have defective nitrate transport. To test if MtNIP/LATD was a nitrate transporter, Xenopus laevis oocytes and Arabidopsis thaliana mutant plants Atchl1-5, defective in a major nitrate transporter AtNRT1.1(CHL1), were used as surrogate expression systems. Heterologous expression of MtNIP/LATD in X. laevis oocytes and Atchl1-5 mutant plants conferred on them the ability to take up nitrate from external media with high affinity, thus demonstrating that MtNIP/LATD ...
Photochemical and Photophysical Properties of Mononuclear and Multinuclear Closed Shell D10 Coinage Metal Complexes and Their Metallo-organometallic Adducts
This dissertation covers the studies of two major topics: the photochemistry of mononuclear and multinuclear gold(I) complexes and synthetic approaches to tailor photophysical properties of cyclic trinuclear d10 complexes. First a detailed photochemical examination into the photoreactivity of neutral mononuclear and multinuclear gold(I) complexes is discussed, with the aim of gold nanoparticle size and shape control for biomedical and catalysis applications. Next is a comprehensive systematic synthetic approach to tailor the photophysical properties of cyclic trinuclear d10 complexes. This synthetic approach includes an investigation of structure-luminescence relationships between cyclic trinuclear complexes, an examination into their π-acid/π-base reactivity with heavy metal cations and an exploration into the photophysical properties of new heterobimetallic cyclic trinuclear complexes. These photophysical properties inspections are used to screen materials for their employment in molecular electronic devices such as organic light-emitting diodes (OLEDs) and thin film transistors (OTFTs).
The Effect of Menthol on Nicotine Metabolism: a Cross Species Evaluation
The effect of menthol on nicotine metabolism was examined in liver S9 fractions of four different species and in the in vivo mouse model. The purpose of this study was to investigate three parameters: (1) biotransformation of nicotine to cotinine in various species (human, mouse, rat and trout) using in vitro methods; (2) to determine if the addition of menthol with nicotine altered biotransformation of nicotine to cotinine; (3) and to assess similar parameters in an in vivo mouse model. The major findings of this study include: (1) mice appear to metabolize nicotine, over time, in a manner similar to humans; (2) menthol decreased cotinine production, over time, after a single dose in mice; and (3) menthol increased cotinine production, over time, after repeated doses, in mice.
Field and Laboratory Fish Tissue Accumulation of Carbamazepine and Amiodarone
The goals of this dissertation work were to assess the bioaccumulation potential of carbamazepine and amiodarone, two widely used ionizable pharmaceutical compounds that possess mid-range and high LogD values, respectively, and to evaluate alternative methods to assess chemical accumulation in bluntnose minnows, catfish, and tilapia. Results indicated that carbamazepine does not appreciably bioaccumulate in fish tissue with BCFk and BAF carbamazepine values < 10. Amiodarone, however, with a log D of 5.87 at pH 7.4, accumulated in fish tissues with kinetic BCF values <2,400. Collectively, the data suggest that full and abbreviated laboratory-derived BCFs, BCFMs derived from S9 loss-of-parent assays, as well as field BAF values are similar for each of the two drugs. In summary, the results from this dissertation indicated: 1) The reduced design BCF test is a good estimate for the traditional OECD 305 test. 2) In vitro S9 metabolism assays provide comparable BCF estimates to the OECD 305 test. 3) Metabolism may play a large role in the accumulation of drugs in fish. 4) Reduced BCF tests and in vitro assays are cost effective and can reduce vertebrate testing.
Shortened in Vivo Bioconcentration Factor Testing in Cyprinus Carpio
Bioconcentration factor testing serves as the most valuable surrogate for the assessment of bioaccumulation. The assessment of potentially harmful chemicals is crucial to not only the health of aquatic environments, but to humans as well. Chemicals that possess the ability to persist in the environment or that have the potential to bioaccumulate, pose a greater risk to organisms that are exposed to these chemicals. The Organization for Economic Cooperation and Development Guideline 305 outlines specific protocols to run an accurate and reliable aquatic flow-through test. However, since its adoption in 1996, very few changes have been made to accommodate the endeavor to lowering the amount of test species to run one of these said tests. Running an aquatic flow-through test, according to 305, takes much time and money as well as numerous amounts of fish. Such burdens can be eliminated through simple modifications to the standard protocols. In this study, we propose an abbreviated study design for aquatic bioconcentration testing which effectively alleviates the burdens of running a flow-through test. Four chemicals were used individually to evaluate the usefulness of the proposed shortened design; 4-Nonyphenol, Chlorpyrifos, Musk Xylene, and DDT. The study consisted of exposing Cyprinus carpio for 7 days followed by 7 days of depuration, for a total of a 14-day study. Our results for each of the four compounds are consistent with literature values, thus, demonstrating that BCFk can be accurately predicted in an abbreviated in vivo test.
Investigation of the Pharmacokinetics of Diazepam in Juvenile Channel Catfish (Ictalurus Punctatus)
The presence of pharmaceuticals in the environment is becoming an increasing regulatory and scientific concern. Thus, the metabolic profile and bioconcentration potential of diazepam, a model benzodiazepine, were examined, as well as effects on the endocrine system in channel catfish. Through the use of specific and non-specific cytochrome P450 (CYP450) inhibitors, it was determined that CYP3A-like enzymes may play a role in the biotransformation of diazepam into temazepam; however, the isoform(s) required for the formation of other metabolites is still unknown. Overall, only around 7-8% of diazepam is biotransformed into two known metabolites. Due to the lack of inherent metabolism of diazepam in channel catfish, further analysis was conducted to determine the tissue-specific bioconcentration potential of diazepam in catfish. Various tissues were analyzed for the presence of diazepam as well as metabolites and bioconcentration factors (BCF) were calculated, which were all well below regulatory threshold values (> 2000). Additionally, modulation of the endocrine system by diazepam was examined by measuring steroid hormone concentrations and analyzing mRNA expression of selected steroidogenic enzymes and receptors. Two steroidogenic enzymes were modulated following diazepam exposure, indicating potential endocrine disrupting properties of diazepam. Together, these data suggest that diazepam exhibits low metabolic transformation rates in channel catfish, which may lead to accumulation of benzodiazepine compounds that may negatively affect the endocrine system. However, further studies should be aimed at identifying other steroidogenic enzymes and/or receptors that may be modulated following diazepam exposure.
Modeling the Effects of Chronic Toxicity of Pharmaceutical Chemicals on the Life History Strategies of Ceriodaphnia Dubia: a Multigenerational Study
Trace quantities of pharmaceuticals (including carbamazepine and sertraline) are continuously discharged into the environment, which causes concern among scientists and regulators regarding their potential long-term impacts on aquatic ecosystems. These compounds and their metabolites are continuously interacting with the orgranisms in various life stages, and may differentially influence development of embryo, larvae, juvenile, and adult stages. To fully understand the potential ecological risks of two candidate pharmaceutical chemicals (carbamazepine (CBZ) and sertraline (SERT)) exposure on survival, growth and reproduction of Ceriodaphnia dubia in three sucessive generations under static renewal toxicity test, a multigenerational approach was taken. Results indicate that SERT exposure showed higher sensitivity to chronic exposure to C. dubia growth and reproduction than CBZ exposure. The lowest concentration to affect fecundity and growth was at 50 µg L-1 SERT in the first two generations. These parameters become more sensitive during the third generation where the LOEC was 4.8 µg L-1. The effective concentrations (EC50) for the number of offspring per female, offspring body size, and dry weight were 17.2, 21.2, and 26.2 µg SERT L-1, respectively. Endpoints measured in this study demonstrate that chronic exposure of C. dubia to SERT leads to effects that occur at concentrations an order of magnitude higher than predicted environmental concentrations indicating potential transgenerationals effects. Additionally, a process-based dynamic energy budget (DEB) model is implemented to predict the simulated effects of chronic toxicity of SERT and CBZ to C. dubia individual behavior at laboratory condition. The model‘s output indicates the ecotoxicological mode of action of SERT exposure, which acts on feeding or assimilation with an effect that rapidly saturates at higher concentrations. Offspring size decreases with the toxic effects on feeding, and offspring number is thus less affected than total investment in reproduction. Consequently, CBZ affects direclty in reproduction which are captured by DEBtox ...
An Instructional Approach to Introducing Twentieth-century Piano Music to Piano Students From Beginning to Advanced Levels: a Graded Repertoire for Mastering the Challenges Posed by Logan Skelton’s Civil War Variations
Beginning and intermediate piano students typically study the repertoire of the eighteenth and nineteenth centuries. This pedagogical approach leaves them underprepared to approach compositions written since the latter part of the twentieth-century which are significantly different in terms of harmony, rhythm, meter, and compositional procedure. Therefore, a step-by-step method is necessary to prepare a student for the challenges of learning twentieth and twenty-first century piano music. Civil War Variations (1988), by Logan Skelton, is an excellent example of a piece that presents a number of challenges characteristically found in late twentieth-century piano music. The twenty-five variations that comprise the work incorporate a series of twentieth-century musical techniques, namely complex rhythms, extreme dissonance, frequent metric changes, dissonant counterpoint, the inclusion of blues scales and rhythms, and new notations. The purpose of this study is to identify the technical, musical, structural and notational challenges posed by a work such as Logan Skelton’s Civil War Variations; examination of this piece will lead to suggestions regarding repertoire that a teacher may assign to beginning, intermediate, and advanced students in order to prepare them logically and in a step-by-step fashion to cope with and meet the challenges posed by this and other compositions having similar characteristics.
The evolution, applications, and statistical interpretations of DNA typing in forensic science
This thesis examines the evolution, applications, and statistical interpretations of DNA typing as a tool in the field of forensic science as well as in our criminal justice system. The most controversial aspect of DNA typing involves the determination of how likely it is that two people share the same DNA profile. This involves the use of population genetics and databases of allelic frequencies as well as some assumptions about population structuring.
Anion exchange and competition in layered double hydroxides
Exchange reactions of anions, especially ferrocyanide and carbonate, with layered double hydroxides (LDHs) were investigated in relation to the origin of life on the early Earth. The effect on ferrocyanide exchange of concentration, pH, reaction time and cations are discussed.
Measuring the learning outcomes of a continuing education seminar about the aging process on the knowledge level of registered nurses
This study aims to increase the level of knowledge about the gerontological knowledge of a sample of registered nurses by creating a portable and concise continuing education seminar that is based upon the fundamental components of the normal aging process.
Dependent personality characteristics and clinical symptomatology in three clinical syndromes in inpatient vs outpatient settings
The purpose of this exploratory study was to investigate the differences between dependent personality characteristics and clinical symptomology as measured by the MCMI-II, in three major psychiatric syndromes in inpatient and outpatient treatment settings.
The nature of reading instruction in a literature-based reading program
The purpose of this study was to describe the nature of reading instruction in a program using children's trade books instead of basal readers, and to identify patterns resulting in hypotheses regarding the nature of instruction.
The effects of music and music vibration using the MVT(tm) on the relief of rheumatoid arthritis pain
The pain relieving efficacy of music listening combined with vibrotactile cutaneous stimulation was determined. Music with mechanical vibration (30min. session; average amplitude of 26μm; frequency range of 60-600Hz.) was applied to subjects with rheumatoid arthritis using the Music Vibration Table (MVT). Scores from pain relief visual analogue scales (VAS) and McGill Pain Questionnaires (MPQ) were compared to groups with music alone and placebo.
The Musica Practica of Bartolomeo Ramos de Pareia: a critical translation and commentary
This dissertation contains the first complete Latin-English translation of one of the most controversial music theory treatises of the fifteenth-century: the Musica Practica (Bologna, 1942) of Bartolomeo Ramos de Pareia. its title as well as its content illustrate the Renaissance transformation from the abstract mathematical approach of "musica speculativa" to that of an emphasis upon the everyday demands of the practicing musician.
An analysis of reading preferences of pilots to develop a book list for aviation education
This study proposed to develop a list of aviation books that experienced pilots consider inspirational and motivational which could be used in an aviation literature course in adult education.
Existence and multiplicity of solutions for semilinear elliptic boundary value problems
This thesis studies the existence, multiplicity, bifurcation and the stability of the solutions to semilinear elliptic boundary value problems. These problems are motivated both by the mathematical structure and the numerous applications in fluid mechanics chemical reactions, nuclear reactors, Riemannian geometry and elasticity theory. This study considers the problem for different classes of nonlinearities and obtain the existence and multiplicity of positive solutions.
Studies on the mechanism of protection by carotenoids against photodynamic killing in Curtobacterium flaccumfaciens pathover poinsettiae
The mechanism of protection by carotenoids against photodynamic killing in Curtobacterium flaccumfaciens pathover poinsettiae (C. poinsettae)was studied using pigment mutants isolated by treatment with nitrosuguandine and DNA gyrase inhibitors.
Early retention in substance abuse treatment: attachment, interpersonal functioning, and perceptions of treatment as predictors
This study was designed to explore the cognitive-perceptual roots of attrition from substance abuse treatment. Previous research on interpersonal issues among substance abusers and attachment theory suggested areas for investigation: the perception of early parental care, current interpersonal functioning, and perception of the substance abuse treatment program.
Postsecondary employment outcomes for youth with serious emotional disturbance: an analysis of national data
The purpose of this study was to identify individual characteristics and school experiences of youth with serious emotional disturbance (SED) that may influence their postsecondary employment status.
A comprehensive review of definitions of adult education
The purpose of this study was to determine the varying definitions of adult education found in major adult education journals and handbooks of adult education published over a period of 40 years, from 1939 through 1979.
Hardware ergonomic considerations in middle school classroom computer and video display terminal installations
The purpose of this study was to determine the extent specific ergonomic factor implementations in computer and video display terminal (VDT) installations for student use in middle school classrooms.
Mercenaries in service to America: the "More Flags" foreign policy of the United States
This study presents the available history of the "More Flags" program during the years of the Johnson Presidency, with an emphasis on the documentation of the program's use as a disguise for america's obtaining military forces from the Republic of Korea, the Philippines and Thailand. The non-mercenary groups from Australia and New Zealand are likewise examined.
A study of the business communication needs and problems of women in entry-level, middle, and upper management positions in Texas
The purpose of this study is to determine the specific business communication needs and problems of women in management positions in selected business firms in Texas. Specifically, this study examines the business communication needs and and problems of women in entry-level managerial positions, women in middle management positions, and women in upper managerial positions.
Correlates of body image in university women
The relationship between maturation rate, body image, depression and eating disorder tendencies was explored in a group of 251 college-age females in order to better understand the developmental progression of body image and related variables.
The role of library science departments of teachers colleges and universities in continuing professional education for librarians in Thailand
This study was designed to investigate the current practice of continuing professional education in the library science departments of teachers colleges and universities in Thailand and the role of the library science department in continuing professional education for librarians.
An ethnographic study of the filial therapy process
Utilizing ethnographic methodology, this study examined and described the filial therapy process to provide an in-depth understanding of the process, the relations in progress, and effects on the parent, child, and parent/child relationship.
Investigation of copper-natural ligand complexes by RP-HPLC photodiode array UV-VIS and fluorescence detection
In this study, reversed phase HPLC with dual UV photodiode (PDA) and fluorescence (FL) detection were used to investigate copper complexes with fulvic, caffeic, vanillic, salicylic, and adipic acids.
Nonlinear optical properties of GaAs at 1.06 micron, picosecond pulse investigation and applications
This dissertation explores both absorptive and refractive optical nonlinearities at 1.06 μm in bulk, semi -insulating, undoped GaAs with a particular emphasis on the influence of the native deep-level defect known as EL2.
Job satisfaction among business administration faculty in selected Iranian universities
This study investigated job satisfaction/ dissatisfaction among business administration faculty at selected public Iranian universities. It also examined the relationship between faculty job satisfaction/ dissatisfaction and selected demographic and professional activity variables. Finally, the extrinsic and intrinsic factors associated with faculty job satisfaction were analyzed.
Physiological and psychological parameters of human touch
The purpose of the present study was to investigate a human being's basic responses to being touched by another human being in a nonreactive context and the effects of an illogical rationale on system disorganization.
Aqueous solubilities and water induced transformations of halogenated benzenes
Methods of determining the aqueous solubilities of twelve chlorinated benzenes were evaluated in pure and in different water matrices. In pure water, results were comparable with the calculated values. Higher chlorinated tetrachlorobenzenes (TeCBs), pentachlorobenzenes (PCBz), and hexachlorobenzenes (HCBs) gave better precision and accuracy than lower chlorinated monochlorobenzenes (MCBs), dichlorobenzenes (DCBs), or trichlorobenzenes (TCBs).
Steepest descent for partial differential equations of mixed type
The method of steepest descent is used to solve partial differential equations of mixed type. In the main hypothesis for this paper, H, L, and S are Hilbert spaces, T: H -> L and B: H -> S are functions with locally Lipshitz Fréchet derivatives where T represents a differential equation and B represents a boundary condition. Define ∅(u)=1/2IIT(u)II^2. Steepest descent is applied to the functional ∅. A new smoothing technique is developed and applied to Tricomi type equations (which are of mixed type).
An analysis of business partnerships in higher education
The major purpose of this study was to describe and analyze the business and higher education partnership program in one Texas community college. Secondary purposes were to describe and analyze (a) the premise of business and higher education partnerships; (b) the planning, organization, and administrative structure in a selected community college; (c) the educational benefits received by both businesses and their employees who are involved in cooperative partnerships in general and at this community college; (d) the future challenges and opportunities for partnerships at other levels of American higher education; and (e) the needed research to evaluate business and higher education partnerships.
Librarians' attitudes toward computers, desktop publishing systems and expert systems
In this study a Q-sort was used to measure differences in academic and public librarian attitudes toward computers, desktop publishing systems and expert systems. Fifty-two academic and sixty-two public librarians responded. The responses were sorted into groups based on the type of library and whether or not the respondent followed the stated Q-sort distribution.
Social-structural and election level determinants of the outcome of union certification elections, 1981-1990
The purpose of this research is to identify major factors that can be used to explain and predict the process of growth in union membership as represented by union victories in certification elections.
The developmentally disabled elderly in Canada: access to health care and social services
The accessibility, predictors, and use of health care and social services among developmentally disabled elderly adults in Canada were examined using a nationally representative social survey.
Concerning integral approximations of bounded finitely additive set functions
The purpose of this paper is to generalize a theorem that characterizes absolute continuity of bounded finitely additive set functions in the form of an integral approximation.
Convergence of conditional expectation operators and the compact range property
The interplay between generalizations of Riezs' famous representation theorem and Radon-Nikodým type theorems has a long history. This paper will explore certain aspects of the theory of bounded linear operators on continuous function spaces, Radon-Nikodým type properties, and their connections.
A new way of statecraft: the career of Elton Mayo and the development of the social sciences in America, 1920-1940
Considered "the father of the science of human relations," Elton Mayo was instrumental in the development of industrial psychology and sociology in America. The career of Elton Mayo and his attraction to influential figures like John D. Rockefeller, Jr., provide a chronological order and interpretive force to understand this development.
A descriptive study of offended responses to nudity in print advertising targeted to women
A discussion of offensiveness in advertising is the initial focus of this research. A review of the offensiveness, irritation, nudity, and sexual suggestiveness in advertising literature suggested that females report somewhat high arousal scores when viewing nudity but that the arousal may not necessarily be positive. The measure of contributing variables to offendedness responses was proposed using various degrees of nudity in existing advertising as the primary stimuli.
Effects of Trichinella soluble antigens on macrophage subpopulations
The immunomodulatory effects of Trichinella spiralis or Trichinella pseudospiralis soluble antigen extracts were examined in an effort to characterize the differences in immune responses seen during these Trichinella infections.
The relationship between low achievement and bodily-kinesthetic intelligence in fourth and fifth graders
The problem of this study was an examination of the relationship between low achievement and physical abilities.This study focuses on the areas of musical, interpersonal, intrapersonal, spatial and bodily-kinesthetic abilities.
Influence of item response theory and type of judge on a standard set using the iterative Angoff standard setting method
The purpose of this investigation was to determine the influence of item response theory and different types of judges on a standard. The iterative Angoff standard setting method was employed by all judges to determine a cut-off score for a public school district-wide criterion-reformed test.
Hospitality education programs in senior colleges and universities in the United States
The purpose of this study was to describe senior-level hospitality programs and assess hospitality administrators' opinions concerning specialized accreditation during the 1990-91 academic year.
Information technology needs of professional education faculty with the implications for the design of information technology systems
This study identified determinants existing within the academic environment of professional education faculty that influence the development and implementation of an information technology system to support their professional endeavors. Such a system would encourage these faculty to integrate technology into their curriculum and, consequently, produce teacher graduates who could employ information technology effectively in teaching.
Relationship of self-esteem in pediatric burn patients to other psychological and physiological parameters
The purpose of this study was to evaluate post-burn adjustment in light of the self-esteem of child burn survivors. The study attempted to assess the viability of using a single, explicit self-report measure of self-esteem (Piers-Harris Children's Self-Concept Scale) as an index of post-burn adjustment.
A descriptive study of statewide bibliographic databases
This dissertation has compiled information about statewide bibliographic databases, their format, their cost, the number of titles and records, how they are being used, what kinds of libraries are using such databases in each state and the effectiveness of those databases.
Negative psychological states: predictors for immunological health
Relationships of negative psychological conditions with general status of cell-mediated and humoral immune systems were investigated. A unique approach was utilized in that indexes representing multiple aspects of each branch of the immune system were employed to better indicate general immunological status.
Higher education in the United Arab Emirates: University of United Arab Emirates and its development
The purpose of this study was to trace the development of education, including higher education, in the United Arab Emirates. In order to complete this study, a computer search of available literature in the English and Arabic languages was constructed.