Thesis (Ph.D. in Nursing) -- University of Colorado, 2006. / Typescript. Includes bibliographical references (leaves 278-301). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;

Cis-diol-containing metabolites have attracted increasing attention in recent years. These metabolites widely exist in the body fluids and tissues. They play important roles in the structure, function and metabolic activity of cells. Some of them are related to cell proliferation and metabolic processes. And they have been used to denote a state of disease as potential biomarkers. Several methods have been developed for the analysis of cis-diol-containing metabolites. However, these methods faced a challenge to separate and detect isomers of these compounds, particularly for compounds with low abundance and high polarity. Therefore, novel methods were necessary to improve the separation and detection sensitivity of this kind of metabolites. With this aim, chemical derivatization methods were developed for cis-diol-containing metabolite detection by using liquid chromatography-mass spectrometry in this project. These methods were optimized and validated to achieve the optimal reaction conditions. And they were applied to study real-world biological systems, including the changes of modified nucleosides in hepatocellular carcinoma (HCC) nude mice and toxic effects of bisphenol A (BPA) exposure. Firstly, the derivatization reaction of cis-diol compounds with acetone were optimized. Factors that affected reaction efficiency were investigated by reacting guanosine (G) with acetone. The optimal reaction conditions were validated by detecting four acetonides of urinary nucleosides by using LC-MS/MS. The results showed that the approach had good linearity, accuracy and precision. The recoveries were ranged from 92.9% to 103.5%. It indicated that the assay was reproducible. The robust method should be potentially useful for the analysis of modified nucleosides and other cis-diol-containing metabolites in biological samples. The validated derivatization method was applied to determine urinary nucleosides by LC-MS. This method not only improved the retention of nucleosides on reversed-phase column, but also reduced the matrix effect from urine samples and enhanced detection sensitivity of mass spectrometry. Isotope labeling method with acetone-d6 and multivariate statistical analysis enabled the positive identification of 56 nucleosides, including 52 modified nucleosides. The obtained results indicated that the derivatization method was practical, fast and effective for the identification of urinary nucleosides. It was successfully applied to study the changes of urinary nucleosides in nude mice bearing HCC. Some significantly changed nucleosides were identified as potential biomarkers. Subsequently, this approach was modified by employing parallel reaction monitoring (PRM) method which was based on high resolution MS to detect urinary nucleosides in rats exposed to BPA. Comparing to the data acquired by triple quadrupole MS with neutral loss scanning, higher specificity and sensitivity were achieved by using PRM scanning mode. Therefore, more nucleosides were identified by using the method in urine samples (from 56 up to 66). The changes of the detected nucleosides were studied in the rats exposed to BPA. Various trends of modified nucleosides were observed with different dose BPA exposure. Specifically, the high-dose exposure group was the most strongly affected. The biomarker of RNA oxidation, 8-hydroxyguanosine (8-oxoG), showed significant change in this group. It proved that BPA exposure could induce RNA damage when the dose of BPA was beyond a certain amount. Except for nucleosides, other cis-diol-containing metabolites, such as carbohydrates, were also studied by using the derivatization method. Acetone and acetone-d6 were applied to label the cis-diol metabolites. Based on the chemical isotope labeling, cis-diol metabolites were easily recognized from urine samples. Influence of BPA exposure on these metabolites was investigated by comparing different doses of BPA administration on rats. Analytes showed noticeable difference were highlighted. Pathway analysis indicated that galactose metabolism, nucleoside and its analogues metabolism were disturbed. The derivatization method was extended to quantify nucleotides in plasma samples. According to the specific physical-chemical properties of nucleotides, the method was improved to fit the requirement of analysis by using 1,1-Dimethoxycyclohexane (DMCH) as derivatization agent and formic acid (FA) as catalyst. Tip micro-columns packed with TiO2 were used for selective adsorption of nucleotides in the plasma. Then in-situ derivatization were carried out to change the polarity of targeted compounds. LC-MS analysis of the derivatization products were employed without using ion-pairing reagents. This method exhibited a high selectivity for the extraction of nucleotides. After derivatization, retention of nucleotides on reversed-phase C18 column was improved. Complete separation of nucleotides with the same base was achieved. The peak shape was symmetrical and the tailing was eliminated by using high pH mobile phase. The method settled the problems of nucleotide detection, which were poor retention, trailing, in-source fragmentation and contamination of ion-pairing reagents. The quantitative method was successfully applied to determine the content of nucleotides in plasma samples of rats exposed to BPA. It was simple and fast, as well as good selectivity and stability. It could be extended to detection of other phosphorylated metabolites with similar structure. To our best knowledge, it was the first time to employ derivatization methods to detect cis-diol-containing metabolites. The methods decreased the matrix effects of complex biological samples, and also decreased the polarity of cis-diol-containing metabolites. The changes of properties not only improved the chromatographic separation, but also enhanced the MS intensities. The methods overcame the problems of cis-diol-containing metabolite detection on reversed-phase column. They were successfully applied to study the changes of cis-diol-containing metabolites of HCC and toxic effects of BPA exposure. The method might be extended to determine other cis-diol-containing metabolites in urine samples as well as in cells, tissues and plasma samples. It might be valuable for the understanding of the roles of cis-diol-containing metabolites in in cell metabolism.

Thesis (M.Tech.) / The electrochemical refining of copper was investigated at different temperatures, distances between electrodes, different levels of overvoltage, current density, metal impurities, smootheners, electrode-active area and concentration of electrolyte using the parallel-plate model. The purpose of the investigation was to evaluate the effect of smootheners, impurities and other factors on the recovery of copper from solutions. The results showed that the metal impurities, with more negative oxidation potentials, did not affect the electro-deposition of copper whilst metals with oxidation potentials close and equal to that of copper reduced the current efficiency. The current density increased with the increase in temperature, overvoltage and concentration of electrolyte. The increase in overvoltage and current density above limiting values produced increased rates of deposition resulting in efficiencies greater than 100% to be attained. The increase in the limiting current density at concentration below 10.8g/L produced low values of current efficiency ranging from 100 to 30%. The 2 and 3cm distance between electrodes produced stable efficiencies of between 92-100% and 96-100% respectively. The temperature was found to have indirect effect on the current efficiency but direct effect on the dissociation of electrolyte in solution, current density and overvoltage. An increase of 20cm2 of electrode active area reduced the current efficiency by about 40%. The increase in concentration of electrolyte produced an increase in the current density and efficiency ranging from 75-100%. The use of smootheners; thiourea and EDTA (Ethylenediaminetetraacetic acid) reduced the current density and current efficiency (100>CE>30%). However increased concentration of Kglue, B-glue and G-Arabic in conjunction with EDTA or thiourea and NaCl improved the current efficiency even at increased levels of overvoltage to levels of 96-100%, 100% and 90-100% respectively. Therefore, the presence of impurities, the use of high current densities, inadequate distance between electrodes, and too low concentration of electrolyte and the absence of glue disadvantaged the recovery process while the presence of K-glue and B-glue reduced the inhibition effects of thiourea and EDTA and thus improved the recovery of copper from solutions.

Thesis (M.Tech.) / The electrochemical refining of copper was investigated at different temperatures, distances between electrodes, different levels of overvoltage, current density, metal impurities, smootheners, electrode-active area and concentration of electrolyte using the parallel-plate model. The purpose of the investigation was to evaluate the effect of smootheners, impurities and other factors on the recovery of copper from solutions. The results showed that the metal impurities, with more negative oxidation potentials, did not affect the electro-deposition of copper whilst metals with oxidation potentials close and equal to that of copper reduced the current efficiency. The current density increased with the increase in temperature, overvoltage and concentration of electrolyte. The increase in overvoltage and current density above limiting values produced increased rates of deposition resulting in efficiencies greater than 100% to be attained. The increase in the limiting current density at concentration below 10.8g/L produced low values of current efficiency ranging from 100 to 30%. The 2 and 3cm distance between electrodes produced stable efficiencies of between 92-100% and 96-100% respectively. The temperature was found to have indirect effect on the current efficiency but direct effect on the dissociation of electrolyte in solution, current density and overvoltage. An increase of 20cm2 of electrode active area reduced the current efficiency by about 40%. The increase in concentration of electrolyte produced an increase in the current density and efficiency ranging from 75-100%. The use of smootheners; thiourea and EDTA (Ethylenediaminetetraacetic acid) reduced the current density and current efficiency (100>CE>30%). However increased concentration of Kglue, B-glue and G-Arabic in conjunction with EDTA or thiourea and NaCl improved the current efficiency even at increased levels of overvoltage to levels of 96-100%, 100% and 90-100% respectively. Therefore, the presence of impurities, the use of high current densities, inadequate distance between electrodes, and too low concentration of electrolyte and the absence of glue disadvantaged the recovery process while the presence of K-glue and B-glue reduced the inhibition effects of thiourea and EDTA and thus improved the recovery of copper from solutions.

Thesis (M.S.)--Medical College of Ohio, 2005. / "In partial fulfillment of the requirements for the degree of Master of Science in Nursing." Major advisor: Janet H. Robinson. Includes abstract. Document formatted into pages: iv, 125 p. Title from title page of PDF document. Bibliography: pages 111-115.

Inefficiencies associated with online information search are becoming increasingly prevalent in digital environments due to a surge in Consumer Generated Content (CGC). Despite growing scholarly interest in investigating users' information search behavior in CGC environments, there is a paucity of studies that explores the phenomenon from a theory-guided angle. Drawing on Information Foraging Theory (IFT), we re-conceptualize online information search as a form of adaptive user behavior in response to system design constraints. Through this theoretical lens, we advance separate taxonomies for online information search tactics and strategies, both of which constitute essential building blocks of the search process. Furthermore, we construct a research framework that bridges the gap between online information search tactics and strategies by articulating how technology-enabled search tactics contribute to the fulfillment of strategic search goals. We validate our research framework via an online experiment by recruiting participants from Amazon Mechanical Turk (AMT). Participants were tasked to perform searches on custom-developed online review websites, which were modeled after a popular online review website and populated with real restaurant review data. Empirical findings reveal that the provision of different search features indeed engenders distinct search tactics, thereby allowing users varying levels of search determination control and search manipulation control. In turn, both types of search controls affects users' result anticipation and search costs, which when combined, determine the efficiency of goal-oriented search strategy and the utility of exploratory search strategy. This study provides valuable insights that can guide future research and practice.

Este estudo trata da construÃÃo e validaÃÃo de um protocolo de terapia de nutriÃÃo enteral para pacientes adultos em uso de sonda enteral. à um estudo metodolÃgico, em que, na sua primeira fase, realizou-se a revisÃo integrativa da literatura a respeito da atuaÃÃo do enfermeiro frente a um paciente adulto com indicaÃÃo de terapia de nutriÃÃo enteral. Para tanto, se procedeu à busca de estudos em bases de dados nacionais e internacionais, onde foram selecionados 36 estudos que atenderam aos critÃrios de inclusÃo, nas bases de dados SCIELO, LILACS, LEYES, MEDLINE, CINAHL e BDTD, apÃs o cruzamento dos descritores controlados: nutriÃÃo enteral, alimentaÃÃo enteral e terapia nutricional, e suas traduÃÃes em inglÃs e espanhol. A leitura e a sÃntese dos estudos apontaram para quatro linhas de atuaÃÃo relacionadas à TNE que orientaram na operacionalizaÃÃo da construÃÃo do protocolo. A coleta de dados com os especialistas aconteceu no perÃodo de junho a setembro de 2012, sendo usado um formulÃrio contendo dados referentes aos especialistas e dados avaliativos do protocolo. O estudo respeitou os preceitos Ãticos e recebeu a aprovaÃÃo do Comità de Ãtica em Pesquisa da Universidade Federal do Cearà sob Protocolo de nÃmero 05/12. A primeira versÃo do instrumento foi composta de duas seÃÃes. A primeira à composta de 20 itens distribuÃdos em seis domÃnios e se refere ao critÃrio de indicaÃÃo da TNE, qual tipo de sonda: oro ou nasoenteral, e ao procedimento da sua inserÃÃo, como deve ser a administraÃÃo de dieta e medicamentos. A segunda seÃÃo possui sete domÃnios com 12 itens que ilustram as situaÃÃes em que pode ocorrer a interrupÃÃo da dieta. O protocolo foi avaliado por meio de cinco itens, que correspondiam a cinco nÃveis de respostas possÃveis dispostas em uma escala de Likert variando de 1 a 5, sendo considerados: 1- inadequado e 5- totalmente adequado. Procedeu-se à anÃlise teÃrica do protocolo, submetendo-se à avaliaÃÃo de 15 especialistas. ApÃs os testes estatÃsticos (coeficiente α de Cronbach e Ãndice de Validade de ConteÃdo) e as alteraÃÃes decorrentes das sugestÃes dos especialistas, obteve-se a segunda versÃo do protocolo formada por duas seÃÃes com 21 itens na primeira seÃÃo, distribuÃdos nos seis domÃnios, e 12 itens na segunda seÃÃo, distribuÃdos em seis domÃnios, e tambÃm com remodulaÃÃo dos itens apÃs anÃlise criteriosa das sugestÃes. Conclui-se, portanto, que foi possÃvel construir um protocolo de TNE e que o mesmo envolve e representa o conteÃdo do constructo que se pretende, pois o coeficiente de correlaÃÃo intraclasse foi α=0,83. Pode-se concluir que a versÃo final do protocolo à vÃlida para usar na prÃtica hospitalar.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / à importante avaliar a prÃtica do autocuidado de pacientes com insuficiÃncia cardÃaca (IC), visto que o cuidado pessoal à indispensÃvel para diminuiÃÃo das complicaÃÃes e reinternaÃÃes e melhoria da qualidade de vida. Este estudo teve como objetivos elaborar uma escala para avaliaÃÃo do autocuidado de pacientes com insuficiÃncia cardÃaca e realizar a validaÃÃo de conteÃdo da escala de avaliaÃÃo do autocuidado de pacientes com insuficiÃncia cardÃaca. Trata-se de um estudo do tipo metodolÃgico, cujo referencial teÃrico foi o Modelo PsicomÃtrico para construÃÃo de instrumentos de medida composto por trÃs procedimentos (teÃrico, empÃrico e analÃtico), sendo realizado o pÃlo teÃrico e seus seis passos. A primeira etapa da pesquisa envolveu o levantamento dos elementos que englobam as mÃltiplas facetas do construto âautocuidado de pacientes com insuficiÃncia cardÃacaâ por meio de uma revisÃo de literatura. Para tanto, procedeu-se a busca de artigos cientÃficos em periÃdicos cientÃficos nacionais e internacionais em bases de dados e livros acadÃmicos sobre IC e autocuidado nas bibliotecas das universidades nos meses de abril e maio de 2011. Foram selecionados 63 artigos, que atenderam aos critÃrios de inclusÃo, nas bases de dados SCOPUS, PUBMED, CINAHL, COCHRANE e LILACS apÃs o cruzamento dos descritores controlados autocuidado e insuficiÃncia cardÃaca e suas traduÃÃes em inglÃs e espanhol. Em relaÃÃo aos livros, selecionaram-se oito livros que atenderam aos critÃrios de inclusÃo estabelecidos. A leitura e sÃntese dos artigos e livros apontaram 28 prÃticas de autocuidado de pacientes com IC e orientaram a operacionalizaÃÃo da construÃÃo da escala, originando a primeira versÃo da Escala de AvaliaÃÃo do Autocuidado de Pacientes com InsuficiÃncia CardÃaca (EAAPIC). A coleta de dados com os juÃzes aconteceu nos meses de agosto, setembro e outubro de 2011, sendo utilizado um formulÃrio contendo dados referentes aos juÃzes e dados avaliativos da escala. O estudo respeitou os preceitos Ãticos e recebeu aprovaÃÃo do comità de Ãtica em pesquisa da Universidade Federal do Cearà sob protocolo de nÃmero 114/2011. A primeira versÃo do instrumento foi composta por 29 itens distribuÃdos em sete domÃnios, quais sejam: nutriÃÃo, eliminaÃÃo, atividade e repouso, percepÃÃo e cogniÃÃo, promoÃÃo da saÃde, tolerÃncia ao estresse e papÃis e relacionamentos. Cada item possuÃa cinco respostas possÃveis dispostas em escala de Likert, variando de 1 a 5, sendo um considerado pior autocuidado e cinco melhor autocuidado. Procedeu-se a anÃlise teÃrica da escala, submetendo-se à avaliaÃÃo de oito juÃzes considerados experts em insuficiÃncia cardÃaca. ApÃs os testes estatÃsticos (Ãndice de Validade de ConteÃdo â IVC, v de Cramer e coeficiente de correlaÃÃo intraclasses - ICC) e as alteraÃÃes decorrentes das sugestÃes dos juÃzes, obteve-se a segunda versÃo da escala formada por vinte itens distribuÃdos em seis domÃnios. O ICC da EAAPIC foi de 0,827 (p=0,001) indicando boa consistÃncia interna. Conclui-se, portanto, que foi possÃvel construir uma escala de avaliaÃÃo do autocuidado de pacientes com insuficiÃncia cardÃaca e que a mesma envolve e representa o conteÃdo do construto que pretende medir devido seu bom valor do coeficiente de correlaÃÃo intraclasses. / It is important to evaluate the practice of self-care of patients with heart failure (HF), as the personal care is essential to decrease complications and readmissions and improve the quality of life. This study aimed to develop a scale for evaluate self-care of patients with heart failure and perform content validation of self-care scale for evaluation of patients with heart failure. It is a methodological study, whose theoretical reference was the Psychometric model for construction of measuring instruments composed of three procedures (theoretical, empirical and analytical), beeing performed the theoretical pole and its six steps . The first stage of the research involved the investigation of the elements that comprise the multiple facets of the construct "self-care of patients with heart failure" through a literature review. For this, we proceeded to search for scientific articles in national journals and international databases and scholarly books about HF and self-care in the university libraries in the months of April and May 2011. We selected 63 articles that met criteria for inclusion in databases SCOPUS, PubMed, CINAHL, Cochrane Library and LILACS after the crossing of controlled descriptors self-care and heart failure and their translations into English and Spanish. Regarding the books, we selected eight books that met the inclusion criteria established. Reading and summaries of articles and books have been identified 28 practice of self-care of patients with HF guided the operationalization of the construction of the scale, resulting in the first version of the Scale of Evaluation of Self-Care of Patients with Heart Failure (EAAPIC). Data collection with the judges took place in August, September and October 2011, we used a form containing data regardings jugdes and evaluate data on the scale. The study complied with the ethical guidelines and was approved by research ethics committee of the Federal University of Cearà under protocol number 114/2011. The first version of the instrument comprised 29 items divided into seven areas, namely: nutrition, elimination, activity and rest, perception and cognition, health promotion, stress tolerance, and roles and relationships. And each item had five possible answers arranged in Likert scale ranging from 1 to 5, with 1 considered worse self- care and 5 the best self-care. There has been the theoretical analysis of the scale, submitting to the evaluation of eight judges considered experts in heart failure. After statistical tests (Index of Validity of Content - IVC and coefficient of intraclass correlation - ICC) and the changes resulting from the suggestions of the judges, we obtained the second version of the scale consisting of twenty items divided in six areas. ICC of EAAPIC was 0.827 (p= 0,001), indicating good internal consistency. We conclude, therefore, that it was possible to construct a evaluation scale of self-care of patients with heart failure and that it involves and represents the content of the construct to be measured due to its good value for coefficient of intraclass correlation.

Increased competition and the scarcity of resources has forced recognition of the significant potential of design to increase the effectiveness and efficiency of the resulting product, system, or structure. Moreover, the design process itself is undergoing a metamorphosis. Its largely sequential nature is giving way to greater concurrency and to the consideration earlier of downstream issues such as production, operation, and retirement. A complete engineering design morphology, enhanced by a sound engineering design evaluation methodology, can enable the realization of systems that meet user needs more effectively and efficiently. Isolated groups are researching diverse ways to better integrate design evaluation within the engineering design process. The need is for increased communication between these research groups for mutual benefit. A representative set of design evaluation methodologies is studied and critically reviewed in this thesis. This work is a step towards increased understanding between the different "schools of thought" and a baseline for further research. / Master of Science

The development of the science of micropropagation from the very initial concept of totipotency to the modern day advancement and sophistication has been affected by a wide range of problems such as hyperhydricity, shoot-tip necrosis and somaclonal variation. These problems are largely the result of the obvious fact of trying to grow plants in an environment that is different from the one plants are used to naturally. The extent of these problems ranges from minor technical inconvenience to significant economic loss. Characterization and control of micropropagation problems has been one of the priorities of plant tissue culture research due to the enormous contribution of this discipline for plant production, improvement and conservation. The prevalence and severity of these tissue culture problems varies widely among plant species. The rationale of this research project was therefore, to identify plant species most affected by the problems studied, characterize the problem and find mechanism(s) to control or minimize the damage caused by the problem. The literatures reviewed provide sufficient background information for the experimental chapters. Due to the different nature of the problems and variation in the plant species they affect, the model plant, the methodologies used and parameters analysed were also different. The findings of these investigations, in their own different way, addressed certain problems that individually and collectively pose difficulties to the micropropagation industry. The difference in the content of the experimental chapters is therefore the result of the broader objective of the research project to tackle such difficulties. The success and failure of tissue culture system greatly depends on the choice of PGR’s. This choice can be made based on comparative study of their biological activity. Some promising reports on the role of topolins in micropropagation led to the idea of testing these cytokinins for their potential in tissue culture. As a prerequisite to subsequent investigations, the biological activity of some selected topolins and BA derivatives was tested using the soybean callus bioassay. The activity of the cytokinins tested varied significantly. The results demonstrated that the structure of a cytokinin dictates its activity. Modifications of side-chain improved the activity of oT but had no effect on pT. The presence of the methyl group had an enhancing effect on cytokinin activity of topolins or at least it did not reduce it. BA derivatives BA9THP (conjugated at N9 position), 3FBA and 2Cl6(3OHBA)R (halogenated derivatives) also showed good cytokinin activity and hold good promise for future research. In an attempt to alleviate hyperhydricity in Aloe polyphylla and optimize the micropropagation protocol, meta-topolin and its derivatives were tested at various concentrations together with BA and zeatin. Of all the cytokinins tested mT produced the best results in terms of shoot and root growth. Five μM was found to be the optimum concentration at which complete control of hyperhydricity was achieved without compromising shoot and root growth. Plantlets rooted in a multiplication media. BA generally had a negative effect on growth and development both in vitro and ex vitro. Acclimatization of plantlets was achieved easily by initially transferring plantlets to a mist house (for three weeks) followed by transfer to the greenhouse. The type of cytokinin also had an effect on ex vitro growth with BA-treated plants producing the lowest shoot and root biomass. Various experiments were conducted to characterize and control factors affecting STN in Harpagophytum procumbens. Media type and strength, PGR, carbon sources, sub-culturing, calcium and boron were tested. Results indicated that all of the tissue culture components tested affected STN. From the different media types tested, half strength was MS found to be the preferred medium. Increasing cytokinin concentration increased the incidence of STN and the problem was aggravated by the addition of auxin to the multiplication medium. Optimum shoot multiplication was achieved by omitting auxin and using the cytokinin mTR. Plantlets produced basal callus which interfered with rooting. The quantity of this basal callus was minimum when mTR was used. Sub-culturing plantlets onto fresh medium every two weeks helped minimize STN. Off all the sugars tested 3% sucrose was optimum. Other sugars either aggravated STN or inhibited growth when compared at equi-molar concentration. Increasing the concentration of either Ca or B prevented the development of necrotic shoots. When the concentration of both elements is increased simultaneously negative effects on both growth and STN were observed. Using 6 mM Ca in half strength MS medium was optimum. B was toxic at higher concentrations. Plantlets rooted readily in half strength cytokinin-free MS media supplemented with 2.5 μM IAA. Rooted plantlets produced using the optimized protocol were acclimatized successfully by transferring directly to a greenhouse in a 1:1 ratio of sand and soil mixture. The effect of meta-toplins on micropropagation and somaclonal variation of banana was investigated. Tissue cultured explants of cultivars ‘Williams’ and ‘Grand Naine’ were cultured in MS media containing the cytokinins BA, mT, MemT, MemTR and mTR at various concentrations. Results of the investigation revealed that superior multiplication and lower abnormality index was recorded from the mTR and mT treatments at 22.2 μM concentration. These treatments, however, had an inhibitory effect on rooting. The effect of these treatments (22.2 μM mT and mTR) in comparison with equi-molar concentration of BA on somaclonal variation of ‘Williams’ banana was tested using RAPD-PCR at the 7th multiplication cycle. No significant difference was found between the treatments. It should however be highlighted that cultures were initially maintained for three multiplication cycles in media containing BA. The inherent stability and initial effect of BA could have influenced the results. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.