Catalytic activities of metallophthalocyanines towards detection and transformation of pollutants
- Authors: Agboola, Bolade Oyeyinka
- Date: 2007
- Subjects: Phthalocyanines Electrochemistry Pollutants -- Biodegradation Pollutants -- Measurement
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4427 , http://hdl.handle.net/10962/d1006922
- Description: Syntheses, spectral, electrochemical and spectroelectrochemical studies of new thiol-derivatised MPc complexes were satisfactorily carried out. For the first time, spectroelectrochemistry gave evidence for the formation of Ni²⁺/Ni⁺ process in a NiPc complex. Significant insights as to the nature of Fe⁺Pc and Ni⁺Pc spectra were obtained. Transformations of chlorophenols using chemical and photochemical methods are presented. For cobalt tetrasulphophthalocyanine catalysed oxidation of chlorophenols using hydrogen peroxide as the oxidant, types of oxidation products formed depended on the solvent conditions. Photolysis of aqueous solutions of chlorophenols in the presence of immobilised non-transition metal phthalocyanine photosensitisers onto Amerlite® was carried out. For the first time, MPcS[subscript mix] complexes were immobilised on Amberlite® for use in heterogeneous photocatalysis. Photolysis of the chlorophenols resulted mainly in the formation of chlorobenzoquinone derivatives. The generation of singlet oxygen (¹O₂) by these immobilised MPc photosensitisers was found to play a major role in their photoactivities. Modifications of gold electrodes with the newly synthesised thiol-derivatised MPc complexes via electropolymerisation and SAM techniques are presented. Cyclic voltammetry, impedance spectroscopy (NiPcs only) and spectroelectrochemical techniques (NiPcs only) confirmed that the complexes formed films on gold electrodes. Stable and well packed SAM films as evidenced by the voltammetric characterisation were obtained. For the first time, optimisation of the time for SAM formation based on CV technique was studied. First example of a formation of MnPc-SAM was achieved. Catalytic activities of the NiPc towards chlorophenol depended on the nature of the NiPc in the polymer films and also anti-fouling ability of the films depended on polymer film thickness. The FeTBMPc polymer modified gold electrode showed the best catalytic activity in terms of peak potential, E[subscript p] when compared to reported work in literature for nitrate electrooxidation. Cyclic voltammetry and spectroscopy studies showed that the CoPcs, FePcs and NiPcs catalysed nitrite oxidation involve 2 electrons in total while that of McPcs involve 1 electron. Better catalytic performance towards sulphite electrooxidation were obtained for the CoPcs, FePcs and MnPcs which have metal based redox processes within the range of the sulphite electrooxidation peak while the NiPcs which did not show metal based oxidation reaction performed less.
- Full Text:
- Date Issued: 2007
Causes of persistent rural poverty in Thika district of Kenya, c.1953-2000
- Authors: Kinyanjui, Felistus Kinuna
- Date: 2007
- Subjects: Poverty -- Kenya -- History Rural poor -- Kenya -- History Agriculture -- Kenya -- History Kenya -- History Kenya -- Politics and government
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2547 , http://hdl.handle.net/10962/d1002399
- Description: This study investigates the causes of poverty among the residents of Thika District in Kenya over the period 1953-2000. Using the articulation of modes of production perspective, the study traces the dynamics of poverty to the geography, history and politics of Thika District. The thrust of the argument is that livelihoods in the district changed during the period under investigation, but not necessarily for the better. Landlessness, collapse of the coffee industry, intergenerational poverty, and the ravages of diseases (particularly of HIV/AIDS) are analysed. This leads to the conclusion that causes of poverty in Thika District during the period under examination were complex as one form of deprivation led to another. The study established that poverty in Thika District during the period under review was a product of a process of exclusion from the centre of political power and appropriation. While race was the basis for allocation of public resources in colonial Kenya, ethnicity has dominated the independence period. Consequently, one would have expected the residents of Thika District, the home of Kenya’s first president, Mzee Jomo Kenyatta, to have benefited inordinately from public resources during his rule. Kenyatta’s administration, however, mainly benefited the Kikuyu elite. The study therefore demonstrates that during the period under examination, the Kikuyu, like any other Kenyan community, were a heterogeneous group whose differences were accentuated by class relations. Subaltern groups in Thika District therefore benefited minimally from state patronage, just like similar groups elsewhere in rural Kenya. By the late 1970s, the level of deprivation in rural Kenya had been contained as a result of favourable prices for the country’s agricultural exports. But in the subsequent period, poverty increased under the pressures of world economic recession and slowdowns in trade. The situation was worse for Kikuyu peasants as the Second Republic of President Daniel Moi deliberately attempted undermine the Kikuyu economically. For the majority of Thika residents, this translated into further marginalisation as the Moi regime lumped them together with the Kikuyu elite who had benefitted inordinately from public resources during the Kenyatta era. This study demonstrates that no single factor can explain the prevalence of poverty in Thika District during the period under consideration. However, the poor in the district devised survival mechanisms that could be replicated elsewhere. Indeed, the dynamics of poverty in Thika District represent a microcosm not just for the broader Kenyan situation but also of rural livelihoods elsewhere in the world. The study recommends land reform and horticulture as possible ways of reducing poverty among rural communities. Further, for a successful global war on poverty there is an urgent need to have the West go beyond rhetoric and deliver on its promises to make poverty history.
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- Date Issued: 2007
Characterization of WC-VC-Co and WC-VC-TiC-Co hardmetals
- Authors: Hashe, Nobom Gretta
- Date: 2007
- Subjects: Carbides , Hard materials
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10533 , http://hdl.handle.net/10948/522 , http://hdl.handle.net/10948/d1011723 , Carbides , Hard materials
- Description: This thesis contains the results of a study focused on cubic carbide and carbonitride grain growth retardation in hardmetals. Large additions of VC, or VC and TiC, or (W,V)C were made to the WC-Co hardmetal, which was then sintered in vacuum or nitrogen. The effectiveness of Ti as the grain growth inhibitor, and the influence of nitrogen sintering on grain coarsening were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffractrometry (XRD) and atom probe field ion microscope (APFIM). Analysis of vacuum-sintered WC-VC-Co revealed that the cubic carbide grains have a core-rim structure. Ti was found to be a core-rim inhibitor in vacuum-sintered WCVC- TiC-Co. The average cubic carbide grain size distribution for the vacuumsintered materials was narrowed in the Ti-containing hardmetal. The nitrogen-sintered WC-VC-TiC-Co consisted of two phases of cubic carbonitride, one with high Ti-content and the other with high (W,V)-content. The surface region of the nitrogen-sintered WC-VC-TiC-Co was covered with a cubic carbonitride phase. Similar phenomena was observed in nitrogen-sintered WC-VC-Co where two types of carbonitrides were found, those with high V-content and the others with low Vcontent. A gradient zone, consisting of fine WC grains in a Co-rich binder and free from cubic carbonitride grains, was created in the surface region. The nitrogensintered materials consisted of a narrow grain size distribution. The use of (W,V)C as a starting powder affected the mechanical properties of the material with the WC-(W,V)C-Co material being the hardest of those produced in this study. Addition of (W,V)C powder to WC-Co was shown to be the most effective way to limit the cubic carbide grain size during sintering and produce a hard material. The cubic carbide grain size in the material produced this way was the smallest of all studied.
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- Date Issued: 2007
Clients' views on construction and design team competencies
- Authors: Crafford, Gerrit Jacobus
- Date: 2007
- Subjects: Construction industry -- Employees , Core competencies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9679 , http://hdl.handle.net/10948/490 , Construction industry -- Employees , Core competencies
- Description: The effectiveness of the design and construction team in meeting clients’ requirements entirely depends on the competency proficiency of the design and construction teams. This research presents a model of the important competencies required by the design and construction teams in order to provide a competent service as seen by the client. A review of related literature followed by interviews by selected practitioners yielded 29 architectural competencies, 31 civil engineering competencies, 32 construction management competencies, 31 project management competencies, and 33 quantity surveying competencies that were presented in a structured questionnaire. The questionnaire was completed by 52 developers from a census of developers and municipality managers in South Africa. Respondents were asked to rank or rate: the level of importance of each competency for a career in that specific discipline; how evident that competency is in the specific discipline in South Africa; the level of importance of the performance parameters to clients, and the extent to which the various disciplines realise client satisfaction relative to the various performance parameters. The techniques of re-scaling, principal component analysis, content analysis, ranking and quadrant analysis were applied to the data. Results showed a high degree of consistency among respondents in all disciplines, regardless of the demographic differences in the importance of the competencies. A factor solution was obtained for every discipline using principal component analysis on the important competencies of each discipline. The various factor solutions were in turn used to formulate a simplified model. The model shows that the factors are interdependent and interacting. The model indicates that primary competencies for each profession are supported by mostly secondary competencies. These factors v are in turn influenced by the inter-relationships between the practitioners, continued professional development/ research and universities, which are then in turn, influenced the governing bodies. The local and global environment then ultimately influences the governing bodies. An Importance-Evidence quadrant analysis was undertaken in order to integrate the rankings of the current importance levels and current proficiency levels for each discipline’s competencies, which helped to identify areas in which education and training is immediately needed. Respondents ranked all nine performance parameters above average which indicates that there are more than the traditional performance parameters of cost, quality, and time involved in satisfying clients. The research concluded that vital feedback from clients regarding the competencies required by the respective professionals in the design and construction team was obtained.
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- Date Issued: 2007
Collaborative research with traditional African health practitioners of the Nelson Mandela Metropole : antimicrobial, anticancer and anti-diabetic activities of five medicinal plants
- Authors: Van Huyssteen, Mea
- Date: 2007
- Subjects: Medicinal plants -- South Africa -- Port Elizabeth , Healers -- South Africa -- Port Elizabeth , Anti-infective agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10148 , http://hdl.handle.net/10948/663 , Medicinal plants -- South Africa -- Port Elizabeth , Healers -- South Africa -- Port Elizabeth , Anti-infective agents
- Description: The promotion and development of indigenous knowledge pertaining to the traditional African healing system is one of the prime objectives set out by the South African government. Despite excellent research opportunities and funding, the biggest problem with ethnopharmacological research is a lack of interaction with indigenous communities, which tends to dilute the benefits this research has to offer these communities. The primary aim of this study was thus to promote the traditional African healing system through collaborative medicinal plant research with local traditional health practitioners. The research collaboration aimed to validate some biological activities of traditional remedies used by collaborating traditional health practitioners and ensured interactive sessions where scientific literature, research practices, findings and relevant legislation were discussed and debated. The joint development of a medicinal garden was a valuable tool in realising these goals. Aqueous and ethanol extracts of Bulbine frutescens, Ornithogalum longibracteatum, Ruta graveolens, Tarchonanthus camphoratus and Tulbaghia violacea were selected for antimicrobial, anticancer and anti-diabetic screening, because of their sustainable utilisation potential. The ethanol extract of T. violacea produced the best antimicrobial activity on Bacillus subtilis (100% growth inhibition) and Candida albicans (89% growth inhibition) at 250 μg/ml. The EC50 for the ethanol extract of T. violacea against HT29 colon cancer cells was 101 μg/ml. The aqueous extracts of B. frutescens and T. camphoratus (0.5 and 50 μg/ml) produced the highest overall glucose uptake activity in Chang liver and C2C12 muscle cells. T. camphoratus was unanimously chosen by participating practitioners as the plant to be investigated further. The aqueous extract of T. camphoratus increased glucose uptake in C2C12 muscle cells through increased translocation of GLUT4 to the plasma membrane and activation of the PI3-kinase and AMP-kinase pathways. It produced some alpha-glucosidase inhibitory activity at concentrations of ≥ 200 μg/ml. Apart from interactive feedback seminars at which the findings were presented to participating practitioners, all scientific literature regarding the plants was summarised, translated, compiled and given to participating practitioners in written format. An indigenous knowledge agreement has been negotiated and will formalise the collaboration in future. It is recommended that future research focuses on plants with economic development potential that can be cultivated in the medicinal garden.
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- Date Issued: 2007
Contributions to the use of microalgae in estuarine freshwater reserve determinations
- Authors: Snow, Gavin Charles
- Date: 2007
- Subjects: Microalgae -- South Africa , Estuarine ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10620 , http://hdl.handle.net/10948/709 , Microalgae -- South Africa , Estuarine ecology -- South Africa
- Description: The ecologist Garrett Hardin (1968) introduced a useful concept called the tragedy of the commons, which describes how ecological resources become threatened or lost. The term “commons” is based on the commons of old English villages and is symbolic of a resource that is shared by a group of people. If every person were to use each resource in a sustainable fashion it would be available in perpetuity. However, if people use more than their share they would only increase their personal wealth to the detriment of others. In addition, an increase in the population would mean that the size of each share would have to decrease to accommodate the larger number of people. As a result, resources are threatened by personal greed and uncontrolled population growth. Freshwater is an example of a common resource that is under threat in South Africa where the average annual rainfall is less than 60 percent of the global average (Mukheibir & Sparks 2006). The increasing demands for freshwater as well as its eutrophication are major concerns with regards to estuarine health, environmental resource management and human health. The correct management of water is necessary to ensure that it is utilised in a sustainable manner. The National Water Act (No. 36 of 1998) has provided the rights to water for basic human needs and for sustainable ecological function; the Basic Human Needs Reserve and Ecological Reserve are both provided as a right in law. The amount of water necessary for an estuary to retain an acceptable ecological status, known as the Estuarine Ecological Reserve, is determined through the implementation of procedures (rapid, intermediate or comprehensive) compiled by the Department of Water Affairs and Forestry (1999) in its Resource Directed Measures (RDM) for the Protection of Water Resources. The impact of restricted flow on estuaries can be reduced by manipulating the water released from impoundments, the regulation of water abstractions within the river catchment or both (Hirji et al. 2002). The reserve assessment method is designed to evaluate ecosystem requirements by employing groups of specialists from different disciplines. In South Africa, this includes hydrologists, sedimentologists, water chemists and biologists (including microalgae specialists). The use of microalgae in ecological assessments has largely been based on research that was initiated at the Nelson Mandela Metropolitan University (formerly University of Port Elizabeth) and subsequently at Rhodes University (Grahamstown) and the University of KwaZulu Natal (Durban). The microalgal research can be divided into two main focus areas; phytoplankton and benthic microalgae
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- Date Issued: 2007
Development of an in-situ ß-D-Glucuronidase diagnostic moraxella-based biosensor for potential application in the monitoring of water polluted by faecal material in South Africa
- Authors: Togo, Chamunorwa Aloius
- Date: 2007
- Subjects: Water quality management -- South Africa Water quality bioassay -- South Africa Sewage sludge -- South Africa -- Management Water -- Purification -- Biological treatment -- South Africa Biosensors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3947 , http://hdl.handle.net/10962/d1004006
- Description: The prevention of outbreaks of waterborne diseases remains a major challenge to public health service providers globally. One of the major obstacles in this effort is the unavailability of on-line and real-time methods for rapid monitoring of faecal pollution to facilitate early warning of contamination of drinking water. The main objective of this study was to develop a β-glucuronidase (GUD)-based method that could be used for the on-line and real-time monitoring of microbial water quality. GUD is a marker enzyme for the faecal indicator bacteria Escherichia coli. This enzyme breaks down the synthetic substrate p-nitrophenyl-β-D-glucuronide (PNPG) to D-glucuronic acid and p-nitrophenol (PNP), which turns yellow under alkaline pH. The enzymatically produced PNP was used to detect GUD activity. In situ GUD assays were performed using running and stagnant water samples from the Bloukrans River, Grahamstown, South Africa. The physico-chemical properties of environmental GUD were determined, after which a liquid bioprobe and a microbial biosensor modified with Moraxella 1A species for the detection of the enzyme activity were developed. In order to determine the reliability and sensitivity of these methods, regression analyses for each method versus E. coli colony forming units (CFU) were performed. The storage stabilities of the bioprobe and biosensor were also investigated. The physico-chemical properties of in situ GUD were different from those of its commercially available counterpart. The temperature optimum for the former was between 35 and 40 °C while for the latter it was 45 °C. Commercial (reference) GUD had a pH optimum of 8.0 while the environmental counterpart exhibited a broad pH optimum of between pH 5.0 and 8.0. The liquid bioprobe had a limit of detection (LOD) of GUD activity equivalent to 2 CFU/100 ml and a detection time of 24 h. The method was less labour intensive and costly than the culturing method. The liquid bioprobe was stable for at least four weeks at room temperature (20 ± 2 °C). The biosensor was prepared by modifying a glassy carbon electrode with PNP degrading Moraxella 1A cells. The biosensor was 100 times more sensitive and rapid (5-20 min) than the spectrophotometric method (24 h), and was also able to detect GUD activity of viable but non-culturable cells. Thus it was more sensitive than the culturing method. Furthermore, the biosensor was selective and costeffective. The possibility of using a Pseudomonas putida JS444 biosensor was also investigated, but it was not as sensitive and selective as the Moraxella 1A biosensor. The Moraxella biosensor, therefore, offered the best option for on-line and real-time microbial water quality monitoring in South African river waters and drinking water supplies.
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- Date Issued: 2007
Enhancing phosphorus availability in some phosphate fixing soils of the Transkei region, South Africa using goat manure
- Authors: Gichangi, Elias Maina
- Date: 2007
- Subjects: Phosphorus in agriculture , Soils -- Phosphorus content , Phosphatic fertilizers , Soils -- Phosphorus content -- South Africa -- Transkei
- Language: English
- Type: Thesis , Doctoral , PhD (Soil Science)
- Identifier: vital:11960 , http://hdl.handle.net/10353/80 , Phosphorus in agriculture , Soils -- Phosphorus content , Phosphatic fertilizers , Soils -- Phosphorus content -- South Africa -- Transkei
- Description: Low availability of soil phosphorus (P) caused by strong sorption of P is a major constraint to agricultural production in most South African soils, particularly those from the high rainfall areas. The aim of this study was therefore to investigate whether combined addition of goat manure with inorganic P fertilizers could enhance P availability in some P fixing soils of the Transkei region, South Africa. The study addressed the following specific objectives (i) to assess P sorption capacities and requirements of selected soils and their relationship with selected soil properties and single point sorption test, (ii) to assess the effects of goat manure and lime addition on P sorption properties of selected P fixing soils (iii) to assess the temporal changes in concentration of inorganic and microbial biomass P fractions following application of inorganic fertilizer P with goat manure in a laboratory incubation experiment, and, (iv) to assess the effects of goat manure application with inorganic phosphate on inorganic and microbial biomass P fractions, P uptake and dry matter yield of maize. Sorption maxima (Smax) of seven soils examined ranged from 192.3 to 909.1 (mg P kg-1) and were highly and positively correlated with sorption affinity constant (r = 0.93, p = 0.01) and organic C (r = 0.71, p = 0.01). The amount of P required for maintaining a soil solution concentration of 0.2 mg P l-1 ranged from 2.1 to 123.5 mg P kg-1 soil. Soils collected from Qweqwe (a Cambisol), Qunu (an Acrisol), Ncihane (a Luvisol) and Bethania (a Ferralsol) had lower external P requirement values and were classified as lower sorbers, whereas soils from Ntlonyana (a Planosol), Chevy Chase (a Ferralsol) and Flagstaff (a Ferralsol) were classified as moderate sorbers. The results suggested that P availability could be compromised in 43 percent iii of the soils studied and that measures to mitigate the adverse effects of P sorption were needed to ensure that P is not a limiting factor to crop production, where such soils are found. Goat manure addition at varying rates (5, 10 and 20 tha-1 dry weight basis) to two of the moderately P fixing soils from Chevy Chase and Flagstaff, reduced P sorption maxima (Smax) compared to the control treatment. Phosphate sorption decreased with increasing amounts of goat manure in both soils but the extent of reduction was greater on Chevy Chase soil than on Flagstaff soil. The relative liming effects of the different rates of goat manure followed the order 20 t GM ha-1 > 10 t GM ha-1 > 5 t GM ha-1. In a separate experiment, addition of inorganic P at varying rates (0, 90, 180, and 360 kg P ha-1) to Flagstaff soil increased labile P fractions (resin P, biomass P and NaHCO3-Pi) and the increases were greater when goat manure was co-applied. The control treatments contained only 17.2 and 27.5 mg P kg-1 of resin extractable P in the un-amended and manure amended treatments, respectively which increased to 118.2 and 122.7 mg P kg-1 on day 28 of incubation. Biomass P concentration was increased from 16.8 to 43.9 mg P kg-1 in P alone treatments but the fraction was greatly enhanced with manure addition, increasing it from 32.6 to 97.7 mg P kg-1. NaOH-Pi was the largest extractable Pi fraction and ranged from 144.3 to 250.6 mg P kg-1 and 107.5 to 213.2 mg P kg-1 in the unamended and manure amended treatments, respectively. Dry matter yield and P uptake by maize grown in the glasshouse were highly and significantly (p = 0.05) correlated with the different P fractions in the soil. The correlations followed the order resin P (r = 0.85) > NaOH-Pi (r = 0.85) > NaHCO3-Pi (r = 0.84) >> biomass P (r = 0.56) for dry matter yield at 6 weeks after planting. At 12 weeks after planting, goat manure had iv highly significant effects on resin P and biomass P but had no effect on NaHCO3-Pi and NaOH–Pi. The combination of biomass P, resin P and NaHCO3-Pi explained 75.8 percent of the variation in dry matter yield of which 63.0 percent of the variation was explained by biomass P alone. The greatest increase in biomass P occurred when added P was co-applied with 5 or 10 tha-1 goat manure. The predictive equation for maize dry matter yield (DM) was: DM (g) = 1.897 biomass P + 0.645 resin P (r = 0.73). Resin P was the fraction that was most depleted due to plant uptake and decreased by 56 to 68 percent between the 6th week and the 12th week of sampling indicating that it played a greater role in supplying plant available P. The results therefore suggested that the use of goat manure may allow resource poor farmers to use lower levels of commercial phosphate fertilizers because of its effect to reduce soil P sorption. In addition, higher increases in biomass P due to manure addition observed at lower rates of added P indicated that goat manure has potential for enhancing bioavailability and fertilizer use efficiency of small inorganic P applications.
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- Date Issued: 2007
Evolutionary and biogeographic studies in the genus Kniphofia moench (Asphodelaceae)
- Authors: Ramdhani, Syd
- Date: 2007
- Subjects: Asphodelaceae Asphodelaceae -- Genetics Cladistic analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4220 , http://hdl.handle.net/10962/d1003789
- Description: Kniphofia, a genus of approximately 71 species, is almost entirely African with two species occurring in Madagascar and one in Yemen. Commonly known as ‘red hot pokers’ they are popular among horticulturists. The genus is also well known for its complex alpha taxonomy. To date, no studies have examined the phylogenetic relationships among species or the evolutionary history of the genus, and little work has been done on their biogeography. The main focus of this study was (i) to review the alpha taxonomy, (ii) to assess diversity and endemism in Kniphofia, (iii) to use DNA sequence data to reconstruct a specieslevel phylogeny to understand intra-generic species relationships and evolutionary processes (iv) to use phylogeographic approaches to study the biogeography and evaluate biogeographical patterns, and (v) to assess anatomical variation and determine if anatomical characters are useful for species delimitation. It was found that the genus has six centres of diversity, five of which are centres of endemism. The South African Centre is the most speciose and is also the largest centre of endemism. Kniphofia shows a strong Afromontane grassland affinity in Tropical and East Africa. In South Africa, it is found from high altitudes to coastal habitats, with the most speciose regions being Afromontane grasslands. It is thus not considered to be an Afromontane element, but rather an Afromontane associate. Five major evolutionary lineages were identified using cpDNA sequence data (trnT-L spacer), four of which are southern African. The fifth lineage is represented by material from Madagascar, East and Tropical Africa. The nuclear ITS region failed to provide resolution, as many sequences were identical. The five lineages recovered using cpDNA showed some congruence with geographic origin rather than the taxonomic arrangement based on morphology. All of the species with multiple samples were non-monophyletic. This could be due to hybridisation and/or incomplete lineage sorting. The nested clade analysis, although preliminary, did not completely agree with the phylogenetic analyses. One of the three third level nested clades appears to show fragmentation between the Cape Region, KwaZulu-Natal and northern parts of southern Africa. Furthermore, another nested clades recovered suggest a range expansion and radiation from the Drakensberg into the adjacent Drakensberg-Maputoland-Pondoland transition. Morphological species of Kniphofia exhibited substantial leaf anatomical variation and anatomical characters do not cluster samples into their morphological species. The anatomical results do not fit any geographic pattern, nor do they correspond to the lineages recovered using molecular markers or the nested clades. Leaf anatomical variation does not appear to be influenced by geographical or environmental factors. However, hybridisation may play a role but was not tested in this study. In light of the above findings it is proposed that the evolutionary and biogeographic history of Kniphofia is strongly linked to tectonic events, and Quaternary climatic cycles and vegetation changes. Tectonic events (viz. uplifts) may have resulted in vicariance events that may account for the five cpDNA lineages recovered in phylogenetic analyses, while Quaternary climatic cycles and vegetation changes may have had a more recent impact on evolution and biogeography. It is hypothesised that the ancestral area for Kniphofia was much more widespread when Afromontane grasslands were more extensive during cooler and drier glacial episodes. Kniphofia on the high mountains of Tropical and East Africa would have tracked Afromontane grasslands as they expanded their ranges in cooler periods. While during wetter and warmer interglacial periods Kniphofia would have retreated into refugia on the mountains of Tropical and East Africa, with no gene flow possible between these refugia. In South Africa, where latitude compensates for altitude, Kniphofia may have maintained a distribution that extended into the lowlands even during interglacials. A cyclic climate change hypothesis implies that populations of Kniphofia (at different phases of the climatic cycle) would have experienced periods of contractions and fragmentation followed by periods of range expansion and coalescence or secondary contact. Altitudinal shifting is proposed to be the most likely mechanism for fragmentation and range expansion, and would would possibly promoted hybridisation. Within the five lineages there is evidence for recent differentiation as the branch lengths are short, there are numerous nonmonophyletic species and numerous identical haplotypes (cpDNA and ITS) which collectively indicate a recent radiation in southern Africa. A recent radiation would also account for the taxonomic confusion and difficulty in differentiating morpho-species. These climatic events may also account for the substantial anatomical variation in southern African Kniphofia species.
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- Date Issued: 2007
Exploring the construct-related validity of the personal-social subscale of the Griffiths Mental Development Scales-extended revised (GMDS-ER)
- Authors: Moosajee, Shaheda
- Date: 2007
- Subjects: Psychological tests for children , Griffiths Scales of Mental Development
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9934 , http://hdl.handle.net/10948/572 , http://hdl.handle.net/10948/d1011708 , Psychological tests for children , Griffiths Scales of Mental Development
- Description: Child assessment has become imperative today as parents and teachers recognize the need for early diagnostic assessments to adequately cater for children’s’ diverse and growing needs so that children can benefit from services and attention in a psychological or educational setting. The Griffiths Mental Development Scales, an established and well-researched instrument is reported to be one of the most carefully designed measures of child development . Studies in various parts of the world have demonstrated that the Griffiths Scales are applicable to diverse populations and that they tap experiences that are common to different cultures. The recent revision and restandardisation of the Griffiths Mental Developmental Scales-Extended Revised (GMDS-ER) has necessitated investigations into its psychometric properties. In view of the important role that assessment measures play in the early identification of developmental delays, it is important that assessment measures are reliable and valid for their intended purpose(s). This study, which is part of a larger research project, attempted to explore and add further evidence of the construct validity of one of the six Subscales of the GMDS-ER, namely the Personal-Social Subscale (Subscale B). An exploratory-descriptive design using a triangulation approach was utilized to explore the construct validity of the Personal-Social Subscale. A nonprobability purposively selected sample of 18 experts working with children participated in the facet analysis to identify the constructs underlying Subscale B (the qualitative aspect of the study). The sample for the quantitative aspects of this study (i.e., the empirical validation of the identified constructs) was collected as part of the broader restandardisation and represented a stratified random sample of 1026 children between the ages of 3 and 8 years from across the United Kingdom and Eire. Three measures, namely a biographical questionnaire, the GMDS-ER and a construct evaluation form were used to gather the qualitative and quantitative data. The qualitative data was analysed by means of facet analysis and literature control. The quantitative data was analysed by using exploratory common factor analysis using oblique (DQUART) rotation to empirically verify the qualitatively identified construct model by specifying a onefactor solution for each underlying construct.
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- Date Issued: 2007
Field and laboratory analyses of manual tasks in the South African automotive industry
- Authors: James, Jonathan Peter
- Date: 2007
- Subjects: Automobile industry and trade -- South Africa -- Safety measures , Human engineering -- South Africa , Automobile industry workers -- South Africa -- Health risk assessment , Industrial safety -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5121 , http://hdl.handle.net/10962/d1005199 , Automobile industry and trade -- South Africa -- Safety measures , Human engineering -- South Africa , Automobile industry workers -- South Africa -- Health risk assessment , Industrial safety -- South Africa
- Description: The present study adopted a “field-laboratory-field” approach in the assessment of the efficacy of ergonomics interventions specific to two selected tasks evaluated in a South African automotive industry. Initial field testing was conducted in an Eastern Cape (South Africa) automotive plant where high risk areas were identified during walkthrough ergonomics surveys in conjunction with interaction with operators. Temporal factors and working postures of 12 industrial workers were recorded and observed, while physiological and perceptual responses were assessed. Two priority areas were focused upon for analysis, namely the Paintshop and Bodyshop with the former identified as being the more taxing of the two tasks. Responses of 30 students participating in rigourously controlled laboratory simulations were subsequently collected while completing the two tasks, namely the Paintshop Trolley Transfer (PTT) and Car Door Carriage (CDC) for participants. Working postures, kinematic, physiological and perceptual responses were assessed pre- and post-intervention. Following the laboratory experimentation a basic re-evaluation was conducted at the plant to assess whether the proposed changes had a positive effect on working postures, physiological and perceptual responses. The results of the preliminary field investigation revealed a prevalence of awkward working postures and excessive manual work in both areas. Laboratory experimentation revealed a notable reduction in task demands pre- versus post-intervention. The PTT mean lean angle for two-handed pre-intervention pulling observations of 23.7° (±3.51) was reduced to 13.9° (±2.21) post-intervention. Low back disorder (LBD) risk was reduced during the two-handed pull intervention (from 36.8% ±8.03 to 21.7% ±5.31). A significant decrement in heart rate responses from 103 bt.min-1 (±11.62) to 93 bt.min[superscript -1] (±11.77) was recorded during the two-handed symmetrical pushing intervention. The electromyography (EMG) responses for one-handed pushing and pulling pre-intervention showed the highest levels of muscular activity in the right medial deltoid due to an awkward and asymmetrical posture. CDC responses demonstrated that minor changes in the storage height of the door resulted in a significant reduction in sagittal flexion from 28.0° (±4.78) to 20.7° (±5.65). Predictions of average probability of LBD risk were significantly reduced from 50.3% (±5.91) to 39.8% (±5.10) for post-intervention car door lifting. In addition, the greatest reduction in EMG activity as a %MVC was achieved during sub-task ii (reduced from 35.1 to 13.7% and 30.5 to 13.9% for left and right erector spinae respectively) which was associated with the introduction of the transfer trolley for the door transfer phase of the CDC. Re-evaluation in the automotive plant revealed that the most notable change has been the implementation of automated ride on trolleys in the Paintshop. The Bodyshop area has also been modified to allow more effective job rotation and the step into the storage bin has been reduced via a “low-cost” stepping platform. Mean heart rate recordings were reduced from 94 (±9.77) bt.min[superscript -1] to 81 (±3.72) bt.min[superscript -1] in the Paintshop. Overall the results demonstrate the effect of “low-cost” interventions in reducing the physical stresses placed on workers in the automotive industry where much of the work is still done manually.
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- Date Issued: 2007
Genesis of environmental education policy in Botswana: construction and interpretation
- Authors: Ketlhoilwe, Mphemelang Joseph
- Date: 2007
- Subjects: Environmental education -- Botswana Education and state -- Botswana
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1549 , http://hdl.handle.net/10962/d1003431
- Description: This study is based on the 1994 Revised National Policy on Education (Botswana Government, 1994) that introduced environmental education into the Botswana’s education system. The main goals of this study were to understand the genealogy of and to critically analyze governmentality associated with environmental education policy in Botswana. Drawing on a post-structural genealogical approach to the subject matter (following Foucault) global historical events and their influence on policy in Botswana, views on environmental education and interpretation, and power relations in environmental education policy discourses were investigated. An investigation was conducted through document analysis, interviews, focus group discussions and observations. The analysis revealed that power relations have historically transcended environmental education policy discourses from global, regional to national levels. The exercise of power through international bodies, and bilateral and multilateral agreements has impacted on Botswana enabling her to enact policies to address socio-ecological crises or regulating them to sustainably utilize natural resources. However, evidence has shown that although Botswana accepted and introduced environmental education, structures were not ready for its implementation and hence some contextual problems are experienced by teachers in schools. The Revised National Policy on Education (RNPE) was constructed through a consultative process, but the final decision on what goes into the policy text was decided from the top (i.e. by the Ministry of Education senior officials). It emerged from this study that Botswana has inconsistently adopted sustainability and conservation-protection discourses in environmental education policy. The mix of the two discourses shows continuity of the protectionist-conservationist discourses and emergence of the current sustainable use discourse, creating a complex discourse environment. The study also revealed that in including these primarily western scientific discourses, other discourses were marginalized or excluded, which revealed continuity with colonial education discourses. The findings also revealed variance in the understanding of environmental education. The majority of the teachers understood and normalised new knowledge in environmental education as Environmental Science or Science, and equated environmental management activities with environmental education. Teachers deployed new governmentalities and normalizing strategies by following the traditional conservation and science epistemological and pedagogical discourses. They exercised various self-governing strategies to respond to the RNPE requirement regarding environmental education. The findings highlight the need for re-conceptualization of environmental education at macro(at Ministry of Education) and micro level. There is a need to harmonize the variation in policy interpretations and clarification of the conservation/environmental education and sustainability discourses running parallel in schools or to work more explicitly with multiple discourses. It has also emerged that teacher support mechanisms need review to enhance policy implementation. The study recommends that further and explicit analysis of environmental education discourses is critical for shaping the future of environmental education policy development and interpretation within Botswana’s education system.
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- Date Issued: 2007
Growth performance, carcass characteristics and meat quality of Nguni, Bonsmara and Angus steers raised on natural pasture
- Authors: Muchenje, Voster
- Date: 2007
- Subjects: Cattle -- Feeding and feeds , Cattle -- Growth , Nguni cattle , Aberdeen -- Angus cattle , Bonsmara cattle , Meat industry and trade -- Quality control
- Language: English
- Type: Thesis , Doctoral , PhD (Animal Science)
- Identifier: vital:11580 , http://hdl.handle.net/10353/199 , Cattle -- Feeding and feeds , Cattle -- Growth , Nguni cattle , Aberdeen -- Angus cattle , Bonsmara cattle , Meat industry and trade -- Quality control
- Description: The objective of the current study was to compare tick loads, growth, carcass characteristics and meat quality of Nguni, Bonsmara and Angus steers raised on natural pasture. A total of 30, 7-month old steers each of Bonsmara and Angus, and 40 Nguni steers were kept at the University of Fort Hare Farm till slaughter at 18 months. Monthly weights of the steers were recorded. Carcasses were electrically stimulated. The m. longissimus thoracis et lumborum was sampled for the measurement of meat colour, pH, drip loss, sarcomere length (SL), water holding capacity (WHC), cooking losses, myofibrillar fragmentation length (MFL), Warner Bratzler shear force (WBSF), fatty acid profiles and sensory characteristics of the steers. Urine samples were collected at the slaughter line for the determination of stress hormone concentrations. The Nguni had the lowest tick load (P < 0.05) while the Angus had the highest tick load (P < 0.05). Tick load did not affect the growth rate and carcass characteristics of the steers. Bonsmara and Angus steers had higher (P < 0.05) carcass weight and dressing percentage than the Nguni steers. Meat quality characteristics were similar (P > 0.05) among all the breeds, except that Nguni meat was darker (L*) (P < 0.05) than meat from the other two breeds. The Bonsmara had the highest (P > 0.05) concentrations while the Nguni had the lowest (P > 0.05) concentrations of stress hormones. There were significant (P < 0.05) correlations between WB values of meat aged for two and 21 days in Nguni and Bonsmara, but not in Angus. The correlations among stress responsiveness hormones and meat quality were breed-dependent. Except monounsaturated fatty acids (MUFA) and the n-6/n-3 ratio, fatty acid profiles among the breeds were similar (P > 0.05). Cholesterol levels among the breeds were similar (P > 0.05). The Nguni had the best (P < 0.05) sensory characteristics, such as flavour and tenderness. It can be concluded that while the Nguni is a small framed breed, its meat quality is similar to that of Bonsmara and Angus and has the best meat taste when raised on natural pasture.
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- Date Issued: 2007
Hermeneutic and empirical analyses of graphically inspired metamathematics that reflect critical consciousness within perspectives of personal and social justice
- Authors: Van Jaarsveld, Pieter Paul
- Date: 2007
- Subjects: Mathematics -- Study and teaching -- South Africa Mathematics -- Study and teaching -- Social aspects -- South Africa Algorithms -- Study and teaching -- South Africa Critical pedagogy Metacognition Hermeneutics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1842 , http://hdl.handle.net/10962/d1004376
- Description: My involvement with mathematics education amongst township educators and learners over the past seven years has highlighted the absence of sustained meaning and meaning making of mathematical concepts. It appears though that this instrumental rather than relational understanding of FET mathematics is not unique to township learners but is encountered amongst learners of all socio-economic classes and is representative of many FET mathematics learners. Given that the language of learning and teaching is a major contributory factor in the South African education system, it appears that the language of mathematics itself is a greater exacerbating factor for many learners of mathematics. The exclusive algorithmic approach to classroom mathematics further seems to alienate many learners from the essence of the meaning of mathematical tasks. This research undertakes to determine whether metateaching and metalearning as forerunners to metacognition facilitates the acquisition of the sustained meaning of mathematical concepts. Metateaching and metalearning refer to the acute and deliberate awareness by educator and learner as to what constitutes concepts. Teaching and learning therefore presupposes the deconstruction of concepts into its subsumed derivative roots. It also assumes an awareness of the tacit degrees of abstraction that characterise tasks and the content of tasks. This in turn has implications for the educator's adopted sequence of topics for instruction. Metacognition implies awareness on the part of the learner (and educator) as to how material is learned and a further awareness as to how that learning can be sustained. Whether we ascribe meaningful learning to radical or social constructivism, or to associationist didactive approaches, or a combination of these, we are making assumptions about how learners acquire and sustain mathematical meaning because mathematics is, by and large a symbolic language often devoid of affective connotation. Furthermore our assessments of learners' tasks amount to clinical corrections of austere formulae wrapped in algorithmic procedures which manifest nothing of a learner's experience of mathematics or the deeper understanding (or misunderstandings) which characterise a learning and/or assessment episode. To this end the research design of this interpretive case study requires learners to expound in textual accounts their thoughts as they describe the evolution of a mathematical process as they approach a solution and eventually interpret it. The textual account exposes the concept definition for what it really is in a learner's understanding of it and it is the expressiveness of language that indicates whether the understanding of a learner is approaching the concept image. The textual accounts vary in richness in terms of mathematical register and this in turn reflects the conceptual depth. The mechanism which seems to promote the conversion from concept definition to concept image is the graphical representation of the mathematical task or procedure, possibly because of its greater concreteness as opposed to the abstraction of its algebraic form.
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- Date Issued: 2007
Inclusive education : a model for in-service teachers
- Authors: Williams, Evelyn Elizabeth
- Date: 2007
- Subjects: Inclusive education -- South Africa , Teachers -- In-service training -- South Africa
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9512 , http://hdl.handle.net/10948/643 , Inclusive education -- South Africa , Teachers -- In-service training -- South Africa
- Description: It is clear that the concept of inclusive education implies that learners experiencing barriers to learning should, wherever possible and with suitable support, be educated with others in a regular school setting and through a regular curriculum. It is assumed that suitable facilities, resources and assistance, where needed, will be available. An adaptable curriculum that accommodates the specific learners who experience barriers to learning is also essential for inclusive education. The focus on providing equal educational opportunities for learners experiencing barriers to learning means that the traditional roles and responsibilities in education will inevitably change. Teachers have to modify their views of themselves, their teaching methods and the roles that they have to play during the implementation of inclusive education. Teachers will have to be adequately trained to effectively and confidently provide appropriate education to learners experiencing barriers to learning. The primary goal of the study is to explore the experiences, perceptions and needs of teachers regarding inclusive education. The secondary goal is to develop a training model to equip in -service teachers better for inclusive education. The research process was structured by the application of a qualitative research approach within a theory generative design, utilising five steps of theory generation in order to reach the objectives of the study. The qualitative approach was selected, as it is exploratory in nature. Founded in this exploratory research, a central concept was identified, with the aim of developing a model to assist teachers in implementing inclusive education. ABSTRACT (xvii) The research was conducted in two phases. The first section of the research comprised an exploration of the experiences, perceptions and needs of teachers regarding inclusive education. It embraced several decisions relating to data collection and analysis processes, such as defining the population and selecting the sample procedure and the data collection method, namely personal interviews with teachers, in order to determine their experiences, perceptions and needs. Concepts in the transcripts were categorised into themes and sub-themes and were verified by a literature review. A central concept was identified ( of the theory-generative research design) that can be further analysed in the second section of the research. The second section of the research was based on the findings of the research and the work of Chinn and Kramer (1995) in order to develop a training model to assist teachers in implementing inclusive education. The following additional steps of model design were employed: - Step Two : Concept definition and classification - Step Three : Construction of relationship statement - Step Four : Description and evaluation of the model - Step Five : Model operationalisation After data analysis was completed, the research established that the participating teachers were not in favour of inclusive education and therefore perceived it negatively. They also viewed themselves as not suitably equipped to work in inclusive settings. They were also discontented and experienced an intense feeling of incompetence. The researcher identified the in teachers as the central concept, which served as the foundation of the design of a model for teachers with regard to inclusive education. The essential criteria of the concept were identified and linked to each other by means of relationship statements. The model was described and evaluated according to the five criteria of clarity; simplicity; generality; accessibility; and significance, as proposed by Step One revitalisation of competence Chinn and Kramer (1995). The researcher also reflected on the limitations inherent to this research study and presented guidelines and recommendations for the operationalisation of the model in practice, to guide future research and in-service training programmes.
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- Date Issued: 2007
Isolation and characterization of genes encoding heat shock protein 70s (hsp 70s) from two species of the coelacanth, Latimeria chalumnae and Latimeria menadoensis
- Authors: Modisakeng, Keoagile William
- Date: 2007
- Subjects: Coelacanth Coelacanth -- Genetics Heat shock proteins Molecular chaperones Proteins -- Analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3971 , http://hdl.handle.net/10962/d1004030
- Description: The extant coelacanths have a close resemblance to the coelacanth fossil records dating back to 230mya. Like their predecessors, the extant coelacanths inhabit rocky caves at a depth of 100-300m below sea level. In the Comoros, the water temperature at these depths is estimated to fluctuate between 14-20°C. High-level adaptation to these environment and lack of competition are thought to have led to the morphological uniformity and slow change throughout the history of the coelacanths. Under stress conditions, proteins unfold or misfold leading to the formation of aggregates. Molecular chaperones facilitate the correct folding of other proteins so that they can attain a stable tertiary structure. In addition, molecular chaperones aid the refolding of denatured proteins and the degradation of terminally misfolded protein after cellular stress. Heat shock proteins form one of the major classes of molecular chaperones. Here we show that, despite high-level adaptation to a unique habitat and slow change, the genome of the coelacanth encodes the major and highly conserved molecular chaperone, Hsp70. Latimeria menadoensis and Latimeria chalumnae contain intronless hsp70 genes encoding Hsp70 proteins archetypal of known Hsp70s. Based on the coelacanth codon usage, we have shown that bacterial protein expression systems, particularly Escherichia coli, may not be appropriate for the overproduction of coelacanth Hsp70s and coelacanth proteins in general. Also interesting, was the discovery that like the rat Hsc70, the L. menadoensis Hsp70 could not reverse thermal sensitivity in a temperate sensitive E. coli DnaK mutant strain, BB2362. We also report the successful isolation of a 1.2 kb region of L. menadoensis hsp70 upstream regulatory region. This region contain three putative heat shock elements, a TATA- box and two CAAT-boxes. This regulatory region resembled the Xenopus, mouse, and particularly tilapia hsp70 promoters, all of which have been shown to drive the expression of reporter genes in a heat dependent manner. Taken together, this data is the first to strongly suggest an inducible Hsp70-base cytoprotection mechanism in the coelacanth. It further provides basis to formulate testable predictions about the regulation, structure and function of Hsp70s in the living fossil, Latimeria.
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- Date Issued: 2007
Management of invasive aquatic weeds with emphasis on biological control in Senegal
- Authors: Diop, Ousseynou
- Date: 2007
- Subjects: Aquatic weeds -- Biological control -- Senegal Invasive plants -- Biological control -- Senegal Aquatic plants -- Biological control -- Senegal
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5728 , http://hdl.handle.net/10962/d1005414
- Description: In 1985 the Diama Dam was built near the mouth of the Senegal River to regulate flows during the rainy season and prevent the intrusion of seawater during the dry season. This created ideal conditions upstream of the dam wall for invasion by two highly invasive aquatic weeds, first by water lettuce Pistia stratiotes Linnaeus (Araceae) in 1993, and then by salvinia Salvinia molesta D.S. Mitchell (Salviniaceae) in 1999. This study was focused on the management of P. stratiotes and S. molesta. Following successes that were achieved elsewhere in the world, biological control programmes involving two weevil species were inaugurated against both weeds and research was focused on several aspects. These included pre-release studies to determine the weevils' host-specificity and impact on the plants in the laboratory, their subsequent mass-rearing and releases at selected sites and post-release evaluations on their impact on the weed populations in the field. Both programmes, which reprepresented the first biocontrol efforts against aquatic weeds in Senegal, proved highly successful with severe damage inflicted on the weed populations and complete control achieved within a relatively short time span. A laboratory exclusion experiment with N. affinis on P. stratiotes showed that in treated tubs, the weevil strongly depressed plant performance as measured by the plant growth parameters: mass, rosette diameter, root length, number of leaves and daughter plants whereas control plants were healthy. Field releases started in September 1994 and water coverage by P. stratiotes at Lake Guiers was reduced by 25% in January 1995 and 50% in April 1995. A general decline of 65% in water coverage by P. stratiotes was observed in June 1995 and by August 1995, eight months after releases P. stratiotes mats were destroyed. Further, although no releases were made there, good results were obtained within 18 months at Djoudj Park water bodies, located 150 km NW from Lake Guiers indicating the potential of the weevil to disperse long distances. In 2005, P. stratiotes reappeared and the weevil N. affinis has located and controlled all of these P. stratiotes recurrences after new releases. In 1999, S. molesta covered an estimated area of 18 000 ha on the Senegal River Left Bank and tributaries (Senegal) and 7 840 ha on the Senegal River Right Bank (Mauritania). Military and Civil Development Committee (CCMAD) and community volunteers made an effort to control S. molesta using physical removal, but this costly and labour-intensive approach was unsustainable. Hence, biological control was adopted by Senegal and Mauritania to manage the weed. Host range tests to assess feeding by C. salviniae on S. molesta and non-target plants and carried out on 13 crop species showed that no feeding damage was observed on the latter and weevils only fed on S. molesta. Field releases of some 48 953 weevils at 270 sites were made from early January 2002 to August 2002. Within one year, weevils were established and were being recovered up to 50 km from the release sites. In a case study conducted at one of the release sites, the S. molesta infestation was reduced from 100% to less than 3% 24 months after release. These results are discussed in the context of the weeds’ negative impact on aquatic systems and riverside communities, and in the involvement of these communities in the programmes.
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- Date Issued: 2007
MISSTEV : model for information security shared tacit espoused values
- Authors: Thomson, Kerry-Lynn
- Date: 2007
- Subjects: Computer security -- Management , Management information systems -- Security measures , Data protection
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9787 , http://hdl.handle.net/10948/717 , Computer security -- Management , Management information systems -- Security measures , Data protection
- Description: One of the most critical assets in most organisations is information. It is often described as the lifeblood of an organisation. For this reason, it is vital that this asset is protected through sound information security practices. However, the incorrect and indifferent behaviour of employees often leads to information assets becoming vulnerable. Incorrect employee behaviour could have an extremely negative impact on the protection of information. An information security solution should be a fundamental component in most organisations. It is, however, possible for an organisation to have the most comprehensive physical and technical information security controls in place, but the operational controls, and associated employee behaviour, have not received much consideration. Therefore, the issue of employee behaviour must be addressed in an organisation to assist in ensuring the protection of information assets. The corporate culture of an organisation is largely responsible for the actions and behaviour of employees. Therefore, to address operational information security controls, the corporate culture of an organisation should be considered. To ensure the integration of information security into the corporate culture of an organisation, the protection of information should become part of the way the employees conduct their everyday tasks – from senior management, right throughout the entire organisation. Therefore, information security should become an integral component of the corporate culture of the organisation. To address the integration of information security into the corporate culture of an organisation, a model was developed which depicted the learning stages and modes of knowledge creation necessary to transform the corporate culture into one that is information security aware.
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- Date Issued: 2007
Molecular characterisation of the chaperone properties of Plasmodium falciparum heat shock protein 70
- Authors: Shonhai, Addmore
- Date: 2007
- Subjects: Heat shock proteins Plasmodium falciparum Protein folding Proteins -- Purification Molecular chaperones Malaria -- Prevention
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3977 , http://hdl.handle.net/10962/d1004036
- Description: Heat shock protein 70 (called DnaK in prokaryotes) is one of the most prominent groups of chaperones whose role is to prevent and reverse protein misfolding. PfHsp70 is a heatinducible cytoplasm/nuclear localised Plasmodium falciparum Hsp70. PfHsp70 is thought to confer chaperone cytoprotection to P. falciparum during the development of malaria fever. The objective of this study was to examine the chaperone properties of PfHsp70 using a bioinformatics approach, coupled to in vivo and in vitro analysis. Structural motifs that qualify PfHsp70 as a typical Hsp70 chaperone were identified. Although PfHsp70 has a higher similarity to human Hsc70 than E. coli DnaK, in vivocomplementation assays showed that PfHsp70 was able to reverse the thermosensitivity of E. coli dnaK756 (a temperature sensitive strain whose DnaK is functionally compromised). Two residues (V401 and Q402) in the linker region of PfHsp70 that are critical for its in vivo function were identified. Constructs were generated that encoded the ATPase domain of PfHsp70 and the peptide binding domain of E. coli DnaK (to generate PfK chimera); and the ATPase domain of E. coli DnaK fused to the peptide binding domain of PfHsp70 (KPf). The two chimeras were tested for their ability to reverse the thermosensitivity of E. coli dnaK756 cells. Whilst KPf was able to reverse the thermosensitivity of the E. coli dnaK756 cells, PfK could not. Previously, PfHsp70 purification involved urea denaturation. Using a detergent, polyethylenimine (PEI), PfHsp70 was natively purified. Natively purified PfHsp70 had a basal ATPase activity approximately two times higher than the previously reported activity for the protein purified through urea denaturation. PfJ4, a type II Hsp40, could not stimulate the ATPase activity of PfHsp70 in vitro. Arch and hydrophobic pocket substitutions (A419Y, Y444A and V451F) were introduced in the PfHsp70 peptide binding domain. Similar substitutions were also introduced in the KPf chimera. PfHsp70-V451F (hydrophobic pocket mutant) had marginally compromised in vivo function. However, a similar mutation (V436F), introduced in KPf abrogated the in vivo function of this chimera. The arch and hydrophobic pocket derivatives of PfHsp70 exhibited marginally compromised in vivo function, whilst equivalent mutations in KPf did not affect its in vivo function. The ability of PfHsp70 and its arch/hydrophobic pocket mutants to suppress the heatinduced aggregation of malate dehydrogenase (MDH) in vitro was investigated. Whilst PfHsp70 arch mutants displayed marginal functional loss in vivo, data from in vitro studies revealed that their functional deficiencies were more severe. This is the first study in which an Hsp70 from a parasitic eukaryote was able to suppress the thermosensitivity of an E. coli DnaK mutant strain. Findings from the in vivo and in vitro assays conducted on PfHsp70 suggest that this protein plays a key role in the life-cycle of P. falciparum. Furthermore, this study raised insights that are pertinent to the current dogma on the Hsp70 mechanism of action.
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- Date Issued: 2007
Narratives of South African heteroseual relationships: understanding masculine and feminine togetherness
- Authors: Tracey, Tiffany
- Date: 2007
- Subjects: Heterosexuality , Heterosexism , Homosexuality , Gender identity
- Language: English
- Type: Thesis , Doctoral , D Soc Sc (Psych)
- Identifier: vital:11601 , http://hdl.handle.net/10353/176 , Heterosexuality , Heterosexism , Homosexuality , Gender identity
- Description: Heterosexuality often appears as a monolithic way of being that has been disciplinarily defined as right and natural for all sexual subjects (Foucault, 1979). However, it may also be viewed as a social construction, subject to alteration and variation according to social and historical context. In the following research, the stories of ten couples and from the South African soap opera Isidingo reveal the ways that heteronorms shape togetherness between men and women. In the research a queer stance is used to interrogate the ways that togetherness appears as natural and normal, such that the contingency of such togetherness is revealed. The queer stance was used to unsettle the unquestioned assumption of heteronormativity by interrogating the construction from a political position not included by the norm (Stein & Plummer, 1994). Within the general queer stance the concept of performance has been used to account for the ways in which subjects are able to unsettle normative constraints: Butler’s (1993) conception of repetition, Holzman’s (1991) account of the revolutionary developmental potential of performance, Billig’s (1991) understanding of the rhetorical constructions of everyday philosophers. Further Bakhtin’s (1994) dialogic ontology suggests that utterances, performances and/or narratives Using these theoretical underpinnings, the narratives show how stories of togetherness collude with heteronorms while at the same time existing alongside alternative forms of togetherness. Possibly because norms are broad, overarching constructions, they do not define the entirety of the couples’ tales. Rather moments of resistance and alteration are interwoven with normative themes. This unpredictable ambivalence appears in the couples narratives as the assertion that all relationships are the same, and that all relationships are unique. Couples position themselves within a social network, and this network instructs the couple on heteronormative ways of being together. They also witness normative performances in a way that is similar to the observation of disciplines, suggested by Foucault (1979). Although couples often go with their social network’s observations, the manner in which couples position themselves within this network assists them in arguing for alternatives to heteronorms. Spatial expressions also at times serve to fix togetherness. Homes are structured in line with social constructions of heteronorms. However, couples can and do mould their understandings of their homes, such space is reveal as an intersection between social and individual concerns. Narratives of work again reveal that heteronorms structure but can also be ignored within heterosexual relationships. Couples tell of receiving particular benefits from normative performances, and it is likely that these dividends make it difficult to opt for an altered version of togetherness. At the same time, the gender dualism of a heteronormative division of labour inserts oppression into togetherness, and this may lead couples to seek an unusual way of being together. In these ways, heterosexuality can be read as a multiple and contingent performance, rather than an immovable, unchangeable imperative.
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- Date Issued: 2007