An empirical phenomenological investigations of the experience of being unemployed : a critical study in the South African context
- Authors: Jaffray, Timothy William
- Date: 1990
- Subjects: Unemployment -- Psychological aspects , Unemployment -- South Africa -- Psychological aspects
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2904 , http://hdl.handle.net/10962/d1002068
- Description: Unemploynent is a problem that confronts many western countries. The aim of this dissertation is to understand, on the basis of a phenomenological investigation, what it means to be an unemployed, white, South African citizen. These meanings are then seen and discussed against the background of the problems associated with the ideological structure within the country. How the latter relates to white employment and psychological life is also explored. The results demonstrate the negative impact unemploynent has upon the psychological functioning of the individual. The results further show the despair such individuals face, having been 'denied' an accepted role within society.
- Full Text:
- Date Issued: 1990
Aspects of the structure and function of some gastropod columellar muscles (Mollusca)
- Authors: Frescura, Mandy
- Date: 1991
- Subjects: Gastropoda -- Research Mollusks -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5642 , http://hdl.handle.net/10962/d1005324
- Description: The columellar muscle of both limpets and coiled shell gastropods is of the paramyosin smooth type. Collagen forms an integral part of the musculature constituting about 35% of the tissue. In limpets, muscle organisation is typical of a muscular hydrostat. Tightly packed blocks of muscle, dense arrays of cross-linked collagen, large muscle cells (9 µm diameter) and thick filaments (70 nm diameter, 30 µm long) produce a tough, relatively rigid but powerful muscle. In coiled shell gastropods, muscle organisation is intermediate between a muscular and a fluid hydrostat. Finer muscle cells (6 µm diameter), thick filaments (60 nm diameter) and a loose intercellular network of collagen interspersed with fluid vesicles are features of a more pliable and extensible muscle. In addition, ultrastructural differences, such as larger numbers of mitochondria and sarcolemmal invaginations distinguish the tarsal from the columellar muscle in both limpets and coiled shell gastropods. About 25% of muscle cells in most species examined, contain a novel arrangement of thin filaments with periodic electron-dense regions. These are similar in appearance to intrafusal cells and stress-fibres of non-muscle cells. Structural analysis of isolated filaments, optical diffraction and SDS gel electrophoresis confirm the, large dimensions and the paramyosin nature of the thick filaments. Microdensitometry of the gel proteins confirms the high proportion of collagen present. No significant differences in muscle ultrastructure were found between limpets from different tidal heights. Muscle attachment areas are shown to be species-specific and positively correlated to tenacity and wave exposure. The muscle attachment mechanism is similar to that described for other molluscs. It consists of a special epithelial layer and a mucous-like material at the muscle-shell interface that possibly has an adhesive function. Although the ultrastructure of Patella is very similar to that of the anterior byssus retractor of Mytilus, its mechanical behaviour is not. The muscle has a narrow working range where maximum tensions and "catch-like" contractions develop. This narrow length range is co-incident with the in situ length at which clamping occurs. It is suggested that the large component of collagen has an important influence over the mechanical behaviour of the muscle during clamping, by cross-linking in a manner similar to that described for some echinoderm connective tissues.
- Full Text:
- Date Issued: 1991
Blessing or curse? : an evaluation of the African Growth Opportunity Act
- Authors: Matenga, Lloyd
- Date: 2017
- Subjects: United States -- African Growth and Opportunity Act Tariff preferences Terms of trade
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10353/8825 , vital:33667
- Description: The core of the commercial relations between the United States (US) and Sub-Saharan African (SSA) countries is primarily based on the advancement of unilateral preferential treatment as envisaged under the African Growth and Opportunity Act (AGOA). AGOA is a bipartisan US legislation promulgated to govern the North-South agreement between the US and SSA countries. Notably, AGOA can be categorized as an exception to the Most Favored Nation (MFN) clause of the General Agreement on Tariffs and Trade (GATT) and consequently under the legal framework of the World Trade Organisation (WTO). The US through the AGOA Extension and Enhancement Act (TPEA) has prolonged the lifespan of AGOA to 2025 in consonance with AGOA and other relevant US legislation. However, there is an ongoing debate as to whether AGOA is working to the advantage or benefit of the eligible SSA countries. This is due to several problematic issues which inter alia relate to the legitimacy of the unilateral preferential treatment, the applicable Rules of Origin (RoO) and the requirement for adoption of robust intellectual property protection regimes as impediments to the enjoyment of AGOA duty and quota free benefits. This study will thus examine the pertinent legal issues underpinning the granting of unilateral preferential treatment in favour of the SSA countries under AGOA and assess the extent to which AGOA complies with or fulfills the purposes and objects of the Enabling Clause.
- Full Text:
- Date Issued: 2017
Contributions to the ecology of the anomuran mud prawn Upogebia africana (Ortmann)
- Authors: Hill, Burke J
- Date: 1967
- Subjects: Decapoda , Shrimps
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5888 , http://hdl.handle.net/10962/d1013341
- Description: Estuarine ecology in South Africa has progressed in two distinct stages. The first of these was a necessary descriptive phase which documented the general distribution of estuarine animals and recorded the physical conditions within estuaries . This phase has been carried out by the Zoology Department of the University of Cape Town which has made a series of ecological surveys of southern African estuaries. These surveys have provided a vast amount of valuable information which was utilised by Day (1964.) to state some general conclusions about estuarine faunas. The most important of these conclusions is that most of the estuarine fauna is really a quiet water fauna which also occurs in sheltered non-estuarine water. The information gained in this first stage is necessarily general and it can only indicate overall trends or reveal major features of distribution. Further estuary surveys are not justified unless they deal with unique conditions. It is at this point that the second phase of estuarine ecology becomes necessary. This phase involves a detailed investigation of individual species or particular problems. The present investigation falls into this second stage of estuarine ecology and was designed to extend our knowledge of the anomuran mud prawn Upogebia africana (Ortmann). The general estuarine surveys have shown that U. africana is a common inhabitant of many estuaries and sheltered bays along the southern African coast from Langebaan on the West coast to Inhambane on the East coast. However these surveys only revealed and could not explain anomalies in its distribution such as its apparent absence from closed estuaries and from estuaries in the tropics. In addition it was not even certain whether this abundant and widespread animal should really be considered a valid species distinct from a common West Coast prawn Upogebia capensis (Krauss). It was felt that a study of an estuarine species should be based upon a sound knowledge of its distribution, population structure and habitat. Knowledge of the habitat must be gained by studies in the field to establish which facets of the environment are of importance to the species. It was decided on the basis of field observations that temperature and salinity are of prime importance: in limiting the distribution of U. africana and a detailed laboratory study was therefore made of the tolerance of U. africana to these two physical factors. The results of laboratory experiments together with field observations were finally used to interpret the ecology of the species. Most of present day knowledge of crustacean ecology has been gained from a study of European and North American animals and information about southern hemisphere species has lagged behind. It is hoped that the present study will contribute to a wider understanding of Crustacea and that it will lead to further more advanced research on South African marine and estuarine animals
- Full Text:
- Date Issued: 1967
Delineation of buried stream channels using geophysical techniques
- Authors: Biedler, Murray W
- Date: 1994
- Subjects: Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4823 , http://hdl.handle.net/10962/d1005498 , Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Description: This study sets out to evaluate the use of geophysical methods for delineating buried stream channels, which can act as zones of preferential flow within a less hydraulically conductive aquifer. This information is important for gaining an understanding of flow dynamics of alluvial systems. The most reliable method of delineating the dimensions of aquifers is by drilling, which is an expensive proposition and is best preceded by a preliminary geophysical study to help define target zones for a drilling program. The study area is located adjacent to the Coerney River in the Sundays River Valley. Geologically it consists of approximately 5 metres of alluvial fines, covering 3 metres of coarse cobbles and boulders, all underlain by alternating siltstone and sandstone beds of indeterminate thickness. Throughout the area the water is very shallow at approximately 2 metres depth and the groundwater tends to be very saline. An air photo study revealed an old oxbow channel that had been covered over by subsequent agricultural land use. The geophysical methods available for the study were portable seismic refraction, electrical resistivity and electromagnetics. Preliminary field tests clearly showed that seismics did not produce valid results. The methods of electrical resistivity and electromagnetics produced good data and were subjected to further assessment. A grid was surveyed over the study area and both geophysical methods were applied at regularly spaced stations. Soil samples were taken over the same survey grid and analyzed for electrical conductivity in a soils laboratory. The results were compared to the geophysical data in an attempt to quantify the relationship between geophysical response and soil salinity. The data from the electromagnetic survey showed areas of low electrical conductivity which was a possible indication of zones of preferential groundwater flow. A transect of boreholes was drilled over selected electrical conductivity lows and successfully intersected the buried stream channel. A comparison of the borehole logs with the layered earth models from the Vertical Electrical Soundings indicated that the electrical resistivity method was not responding to the features of the buried stream channel and the cobblestone layer. This proved the electromagnetic method to be more valuable for this particular study
- Full Text:
- Date Issued: 1994
Friend or foe? : Resolving the status of the submerged macrophyte Myriophyllum spicatum L. (Haloragaceae) in southern Africa
- Authors: Weyl, Philip Sebastian Richard
- Date: 2015
- Subjects: Eurasian watermilfoil -- Africa, Southern , Eurasian watermilfoil -- Biological control
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5933 , http://hdl.handle.net/10962/d1017811
- Description: Myriophyllum spicatum L. (Haloragaceae), a submerged macrophyte, has been recorded in southern Africa since 1829, but only considered problematic as recently as 2005. In light of this, water resource managers are looking to control M. spicatum in southern African water bodies where it is problematic. Amongst control options available in South Africa, biological control is potentially the most cost effective and sustainable option for M. spicatum. However, there is a debate over the status of this plant in southern Africa with several authors reporting it as a native component of the aquatic ecosystem, while others argue that it has been introduced from Europe or Asia. The aim of this thesis is to use a multifaceted approach to resolve the status of M. spicatum, by studying aspects of its history, distribution, mechanisms of its adaptations, biotic interactions and genetic relationships in southern Africa. By resolving the status of this plant as either native or exotic, appropriate management strategies can be initiated for its control in situations where it is considered a problem.A review of the evidence collected from this thesis does not provide convincing evidence for the anthropogenic introduction of M. spicatum into southern Africa, and it is probably native to the region. The disjunct distribution as well as regular local extinctions of populations is relatively common for species that are at the edge of their range. The populations in southern Africa could thus be relics from a much wider distribution in the past. The development of local adaptations in southern Africa provides evidence for this and suggests that the populations have been isolated for a substantial period of time and have had a long evolutionary history in the region. The lack of specialist herbivores should suggest that M. spicatum has been introduced, but the complete lack of herbivores, including generalists, may weaken that argument. The lack of herbivores could be a result of something inherent in the plant, irrespective of a lack of evolutionary history in the region. The genetic evidence suggests a European origin, but is characteristic of a population (southern Africa as a whole) that has been isolated for a considerable time. Despite the findings of this research, M. spicatum is considered problematic in southern Africa and warrants control in certain systems. Whether or not biological control should be a component of the management strategy is open to further debate. The benefits in a southern African context may outweigh the risks, based on the specificity of the biological control agent proposed. However, the perceived negative impacts of M. spicatum are likely to be a symptom of a more serious underlying cause, such as nutrient loading and changes in land use patterns. Therefore the control of this native species is a water resource management issue and not a biological control issue.
- Full Text:
- Date Issued: 2015
Livelihood strategies determinants and ranking across times : evidence from Eastern Cape
- Authors: Sikhunyana, Zintle
- Date: 2018
- Subjects: Households Rural development
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10353/15079 , vital:40161
- Description: The existing literature has acknowledged that analysis of livelihood strategies is more important for rural development policy and also that livelihood strategies are at the centre of development. Persistent challenges of poverty, unemployment and inequality have called for a need to understand livelihood patterns of poor households as to effectively address these socio-economic issues in rural areas. The study aimed to identify determinants of livelihood strategies and to identify livelihood strategies that are superior to others in the rural Eastern Cape province of South Africa for the years 2002-2014. The study used multinomial logistic regression to identify the determinants of livelihood strategies. The findings showed that: age of household head, gender of household head, dwelling type, household size, number of economically active members, size of land that the household uses, and access to electricity statistically determine livelihood strategies of the poor in rural Eastern Cape. With regards to ranking, the study used dominance tests such as the Kruskal-Wallis test and also used one way between groups ANOVA with the post hoc test for additional information. The results from the Kruskal-Wallis test showed that remittances are superior livelihood strategies, and the results from one-way between groups ANOVA with post hoc showed that sales of farm products and services dominate other strategies. Restrictions on land conservation, and promotion of sustainable development have constrained rural households from freely using land in pursuit of their goals. The government needs to reconcile the policy amendments for land use. Furthermore, social grants alone are not sufficient to meet the needs of the poor; there should be alternative strategies on how to take the poor out of poverty.
- Full Text:
- Date Issued: 2018
Mesozooplankton community structure in the vicinity of the Prince Edward Islands (Southern Ocean) 37⁰ 50'E, 46⁰ 45'S
- Authors: Hunt, Brian Peter Vere
- Date: 2000
- Subjects: Zooplankton , Zooplankton -- Prince Edward Islands , Phytoplankton , Chlorophyll
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5732 , http://hdl.handle.net/10962/d1005418 , Zooplankton , Zooplankton -- Prince Edward Islands , Phytoplankton , Chlorophyll
- Description: Mesozooplankton community structure in the vicinity of the Prince Edward Islands (PEIs) was investigated during six surveys conducted in late austral summer (April/May), 1996 to 1999. Each year zooplankton samples were collected with a bongo net (300 µm mesh) at stations upstream (west), between and downstream (east) of the islands. Chlorophyll a concentrations were determined fluorometrically, corresponding with each net tow. The positions of the Subantarctic Front (SAF) and the Antarctic Polar Front (APF), in relation to the islands in the upstream region, were determined by a line of CTD and/or XBT stations. Both the SAF and the APF were characterised by a high degree of meridional variation in position. Changes in position of the fronts were shown to occur very rapidly. In 1999 the APF moved southwards by ~40nm and the SAF northwards by ~60nm in a period of two weeks, while in 1996 the SAF appeared to move ~120nm northwards in a two week period. The positions of the SAF and APF appeared to have a significant impact on phytoplankton biomass in the vicinity of the PEIs, through the alteration of local flow dynamics. Water retention in 1996, associated with the location of the SAF and APF far to the north and south of the PEIs respectively, corresponded with high chlorophyll a concentrations in the inter-island region (reaching 1.54 mg.m^(-3)). When the fronts were close to the islands, in 1997 and 1999, and a flow through environment existed, chlorophyll a concentrations in the inter-island region were comparatively low. Although biomass enhancement was only observed at the SAF in 1996, phytoplankton size structure in 1999 indicated that, when close to the PEIs, frontal production may be transported to the island system. This is potentially an important source of allochthonous input into the island system. Zooplankton assemblages were a mix of sub-Antarctic and Antarctic communities, with a weak presence of sub-tropical species. Cluster analysis showed that during each survey the region in the vicinity of the PEIs was divided into different, spatially separated zooplankton communities, associated with water masses of different origins. These communities were identified by variations in the abundance and biomass of species rather than variation in species composition and, in general, there was a relatively high degree of similarity both within and between surveys. Inter-annual community analysis revealed that, in many cases, there was greater similarity between communities from different years than communities within years, indicating that short-term variability exceeded inter-annual variability. Multiple regression analysis showed that the major correlate with zooplankton community structure during all surveys was sea temperature, accounting for as much as 77% of the variation in community structure. Temperature was indicative of the relative contribution of sub-Antarctic and Antarctic communities, with low temperatures being characterised by an increased predominance of Antarctic communities and vice versa. The differentiation between sub-Antarctic and Antarctic waters, and their respective communities, was particularly pronounced when the SAF and APF were in close proximity to the islands. Surface salinity and sounding had limited effect on community structure. The affect of sounding was intrinsically related to zooplankton interaction with the island ecosystem. Predation by the islands' land based predators and benthic fish appears to decrease zooplankton biomass over the island shelf, particularly the macrozooplankton size fraction. However, this may only be an important factor under conditions of water retention when replenishment of zooplankton stocks is low. The low densities of many macrozooplankton species, and other deep migrators, on the island shelf may be due to their limited advection onto shallow topography. By contrast, there are indications that zooplankton species occurring at shallower depths may be concentrated in the inter-island region by mesoscale flow patterns. Analysis of the population structure of the copepod Calanus simillimus showed that this species occurred at different stages in its life cycle during different years, even though sampling took place in the same calendar months, indicating that there was inter-annual variation in the timing of the biological season. Differences in the population structure of species, and consequently their contribution to abundance and biomass, may therefore have been an important contributor to inter-annual variation in community structure. Evidence is provided for a long-term trend of southward movement of the SAF. This may have a significant affect on the PEI ecosystem, increasing the proportion of allochthonous input and altering the tropho-dynamics of the island ecosystem
- Full Text:
- Date Issued: 2000
Molecular studies on cholera and non-cholera causing vibrio pathogens isolated from some water resources and aquatic animals in Eastern Cape Province, South Africa
- Authors: Abioye, Oluwatayo Emmanuel
- Date: 2018
- Subjects: Vibrio cholerae -- Pathogens Vibrio cholerae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9154 , vital:34283
- Description: The global socioeconomic and disease burdens of cholera; a disease caused by Vibrio cholerae have been ongoing since it was first reported in India in 1563. Unfortunately, emerging non-cholera causing Vibrio pathogens have been contributing to the malady of Vibrio genus globally in the recent years. The history of cholera outbreaks in South Africa have been well documented but information regarding other non-cholera Vibrio pathogens, is deficient in the literature. This study evaluated the statuses of aquatic animals including crustaceans, molluscs, and fish as important reservoirs of six key pathogenic Vibrio spp. in some important water resources and fish markets in the Eastern Cape, South Africa, between December 2016 and November 2017. Physiochemical parameters that are vital for water quality assessment were determined for all the water sampling points using standard methods. The parameters include pH, electrical conductivity (EC), total dissolved solids (TDS), salinity, temperature, total dissolved solids, turbidity and biological oxygen demand (BOD5). Vibrio spp. densities in water and aquatic animal samples were determined using membrane filtration and Most Probable NumberPolymerase chain reaction (MPN-PCR) methods respectively. Presumptive Vibrio spp. were recovered from the samples by direct plating of water samples and aliquots of aquatic animal homogenates on thiosulfate-citrate-bile salts-sucrose (TCBS) agar. Where necessary, samples were enriched using alkaline peptone water (APW) for optimum isolation of the targeted Vibrio spp. Presumptive isolates were identified and delineated into the six targeted pathogenic Vibrio spp. using PCR method. The antibiogram fingerprint of selected Vibrio spp. against a panel 18 panels of antibacterial agents were also carried out. Multiple antibiotic resistance phenotypes (MARPs) per set of isolates from water sampling sites and aquatic animal types were determined. Finally, multiple antibiotic resistance indices (MARI) for isolates recovered from the samples were determined. All experiments were done in replicate and data compared using one-way analysis of variance and one-tail t-test as appropriate. Correlation and regression analysis were also carried out as appropriate. Uncontrolled agricultural, industrial and domestic wastewater influxes, as well as run-off intrusions into the water resources investigated, were observed throughout the sampling season. The physicochemical qualities of the water resources varied with seasons. While pH observed for all the water sampling sites complied with South Africa and international standards, most sampling sites did not comply with set standards for one or more of the remaining physicochemical parameters. The parameters that frequently exhibited significant correlation and regression with Vibrio spp. densities were TDS, TSS, turbidity and temperature. The densities of Vibrio spp. in the samples studied varied with season and the highest density per sample types were observed in the summer. The prevalence of Vibrio spp. in freshwater, brackish water and aquatic animal samples were 79 percent, 78 percent and 86 percent respectively. The respective prevalence of V. cholerae, V. mimicus, V. fluvialis, V.alginolyticus, V. vulnificus and V. parahaemolyticus in freshwater samples (18 percent, 3 percent, ~1 percent, ~1 percent, <1 percent, < percent), brackish water(12 percent, 3 percent, 28 percent,~1 percent, ~1 percent, 9 percent) and aquatic animals (9 percent, 1 percent, 17 percent, 1 percent, 1 percent, 17 percent) were observed. All isolates from all the sample types showed very high antibiotic resistance against ampicillin and polymyxin B. Furthermore, MARPs were observed among isolates from the three sample types. Multiple antibiotic resistance indices (MARI) above 0.2 was observed at one site on Kowie River, three on Kubusi River and one on Buffalo River. The findings of this study suggest that most South Africa water-bodies especially freshwater resources are not well protected. This need to be addressed in a country like South Africa where availability of the freshwater resource for human activities is a critical issue. Base on the prevalence of pathogenic Vibrio spp. especially MARPs and sites that exhibited above 0.2 threshold for MARI, environmental base Vibrio species monitoring programs are recommended.
- Full Text:
- Date Issued: 2018
Novel applications of Morita-Baylis-Hillman methodology in organic synthesis
- Authors: Mciteka, Lulama Patrick
- Date: 2013 , 2013-04-22
- Subjects: Organic compounds -- Synthesis -- Research Asymmetric synthesis Asymmetry (Chemistry) Chemical reactions -- Research Camphor -- Research AZT (Drug) -- Research Chemical inhibitors -- Research Chemistry -- Methodology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4439 , http://hdl.handle.net/10962/d1007598
- Description: The overall approach in the present investigation has been to explore applications of the Morita-Baylis-Hillman (MBH) reaction in asymmetric synthesis and in the continuation of systems with medicinal potential. To this end, a series of varied camphor-derived acrylate esters was prepared to serve as chiral substrates in asymmetric Morita-Baylis- Hillman reactions. Reduction of N-substituted camphor-10-sulfonamides afforded the 3- exo-hydroxy derivatives as the major products. Acylation of the corresponding sodium alkoxides gave the desired 3-exo-acrylate esters, isolation of which was complicated by concomitant formation of hydrochlorinated and diastereomeric competition products. Bulky camphorsulfonamides containing alkyl, dialkyl, aromatic and adamantyl groups were selected as N-substituents with the view of achieving stereoselective outcome in subsequent MBH reactions. The synthesis of novel camphor-derived Morita-Baylis-Hillman adducts using various pyridine-carboxaldehydes proceeded with exceptionally high yields with diastereoselectivities ranging from 7-33 % d.e. Both 1D and 2D NMR and HRMS techniques were employed to confirm the structures and an extensive study of the electropositive fragmentation patterns of a number of camphor-derived chiral acrylate esters was conducted. Attention has also been given to the application of MBH methodology in the construction of heterocyclic ‘cinnamate-like’ AZT conjugates which were designed to serve as dualaction HIV-1 integrase-reverse transcriptase (IN-RT) inhibitors. A number of pyridine carboxaldehyde-derived MBH adducts were synthesized using methyl, ethyl and t-butyl acrylates in the presence of 3-hydroxyquinuclidine (3-HQ) as catalyst. The yields for these reactions were excellent. The resulting MBH adducts were acetylated and subjected to aza-Michael addition using propargylamine. The resulting alkylamino compounds were then used in ‘Click reactions’ to form the targeted AZT-conjugates in moderate to excellent yield. In silico docking of computer modelled AZT-conjugates into the HIV-1 integrase and reverse transcriptase enzyme-active sites and potential hydrogen-bonding interaction with active-site amino acid residues were identified. The electrospray MS fragmentations of the AZT and the novel AZT-conjugates were also investigated and common fragmentation pathways were identified.
- Full Text:
- Date Issued: 2013
Physical organic studies of substituted norbornyl systems: aspects of mechanisms and chirality
- Authors: Singh, Alicia
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/50558 , vital:25999
- Description: Fenchone and camphor are essential natural products that are available optically pure and contribute to the chiral pool in asymmetric synthesis. Further, they are both derivatives of norbornane, a structure that undergoes a remarkable diversity of rearrangements in acidic conditions. This work explores two aspects of the camphor/fenchone derived systems. Firstly an attempt to clarify rearrangement mechanisms on a camphor system successfully via deuterium labelling and unsuccessfully via derivatization of fenchone (with rearrangement) to produce other 13C-labelled camphor substitutions, has resulted in confirmation of a theoretically proposed, highly concerted Wagner-Meerwein, 6,2 - hydride shift, Wagner-Meerwein rearrangement in competition with an associated 2,3-methide shift. Kinetics and activation parameters for many steps have been resolved in this rearrangement of the deuterium labelled camphor-derived tosylate system to two pairs of isotopomers. Further, the kinetics and formation of an unexpected pair of dimers encountered during the scheme for 13C labelling are investigated in detail. These dimers (forming during the initial stages of the synthetic scheme) are unusual in that they are not expected rotamers of each other, but diastereomers resulting from chirality of a sulfur atom in a sulfite moiety. A feasible mechanism of formation that matches the kinetics has been proposed in this unexpectedly complex system, and thermodynamic parameters have been determined. The second aspect of substituted norbornyl systems pertains to their chirality, and the influence of this chirality on reaction mixtures, with an aim to identify novel chiral micellar catalysts for use in heterogeneous reaction mixtures. Headway has been made towards the synthesis of the appropriate surfactants to be used in the construction of these micelles, but extensive molecular dynamics simulations have illustrated the feasibility of forming the stable chiral micelles in a dual-solvent system, and detail precisely the influence of chirality on surrounding media. These studies add important physical organic data as well as show the immense possibilities pertaining to substituted norbornane systems.
- Full Text:
- Date Issued: 2017
Purification and characterization of TbHsp70.c, a novel Hsp70 from Trypanosoma brucei
- Authors: Burger, Adélle
- Date: 2014
- Subjects: African trypanosomiasis -- Research Heat shock proteins -- Research Trypanosoma brucei -- Research Mycobacterial diseases -- Research -- Africa Parasitic diseases -- Africa -- Prevention Parasites -- Physiology Developing countries -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4105 , http://hdl.handle.net/10962/d1011618
- Description: One of Africa’s neglected tropical diseases, African Trypanosomiasis, is not only fatal but also has a crippling impact on economic development. Heat shock proteins play a wide range of roles in the cell and they are required to assist the parasite as it moves from a cold blooded insect vector to a warm blooded mammalian host. The expression of heat shock proteins increases during these heat shock conditions, and this is considered to play a role in differentiation of these vector-borne parasites. Heat shock protein 70 (Hsp70) is an important molecular chaperone that is involved in protein homeostasis, Hsp40 acts as a co-chaperone and stimulates its intrinsically weak ATPase activity. In silico analysis of the T. brucei genome has revealed the existence of 12 Hsp70 proteins and 65 Hsp40 proteins to date. A novel Hsp70, TbHsp70.c, was recently identified in T. brucei. Different from the prototypical Hsp70, TbHsp70.c contains an acidic substrate binding domain and lacks the C-terminal EEVD motif. By implication the substrate range and mechanism by which the substrates are recognized may be novel. The ability of a Type I Hsp40, Tbj2, to function as a co-chaperone of TbHsp70.c was investigated. The main objective of this study was to biochemically characterize TbHsp70.c and its partnership with Tbj2 to further enhance our knowledge of parasite biology. TbHsp70.c and Tbj2 were heterologously expressed and purified and both proteins displayed chaperone activities in their ability to suppress aggregation of thermolabile MDH. TbHsp70.c also suppressed aggregation of rhodanese. ATPase assays revealed that the ATPase activity of TbHsp70.c was stimulated by Tbj2. The targeted inhibition of the function of heat shock proteins is emerging as a tool to combat disease. The small molecule modulators quercetin and methylene blue are known to inhibit the ATPase activity of Hsp70. However, methylene blue did not significantly inhibit the ATPase activity of TbHsp70.c; while quercetin, did inhibit the ATPase activity. In vivo heat stress experiments indicated an up-regulation of the expression levels of TbHsp70.c. RNA interference studies showed partial knockdown of TbHsp70.c with no detrimental effect on the parasite. Fluorescence microscopy studies of TbHsp70.c showed a probable cytoplasmic subcellular localization. In this study both TbHsp70.c and Tbj2 demonstrated chaperone activity and Tbj2 possibly functions as a co-chaperone of TbHsp70.c.
- Full Text:
- Date Issued: 2014
Remedial program on learners’ proficiency in english second language: a case of two township schools in king William’s town education district.
- Authors: Moyo, Thembekile
- Date: 2020
- Subjects: Reading -- Remedial teaching Reading (Elementary)
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10353/17910 , vital:41977
- Description: Literature indicates that there is a national crisis about learners who cannot read for comprehension at the primary level. However, there is limited literature that talks about effective remediation programmes in developing countries. This had a negative impact on the Matric results in the past years. Statistics have always shown the rural provinces such as Eastern Cape to be the most affected province with these poor results, due to the low levels of learners’ reading skills. This study focused on the remedial programme on learners’ proficiency in English second language, which was conducted in two township schools in King William’s Town District. This explored the remedial programme that could be used to help learners become proficient readers who could be able to read for meaning and comprehension. A case study research design was used where two township schools were sampled. A qualitative approach located in the interpretive paradigm was used to carry out the study. The purposive and the sampling procedure were used to solicit information from principals, educators, and learners. The data was collected through interviews, observations and focus groups. Its focus was to establish a remedial programme to improve learners’ proficiency in English second language. The findings revealed that a lack of English proficiency has a negative effect on the learners’ performance. The findings also revealed that the repetition of concepts helps the learners to master and increase their vocabulary and comprehension. A need for learner teacher support materials (LTSM) was revealed to equip the educators with knowledge and skills for teaching diversity in the classroom. The study recommends provision for trained remedial educators in all schools to attend to the individual needs of learners appropriately. Universities should include a component of remedial education in the training of educators, as they are the ones expected to remediate the struggling learners. Parents should encourage their children to be actively involved in learning the language of teaching and learning.
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- Date Issued: 2020
The influence of soccer-specific fatigue on the risk of thigh injuries in amateur black African players
- Authors: Jones, Robert Ian
- Date: 2013
- Subjects: Soccer injuries -- South Africa -- Eastern Cape Thigh -- Wounds and injuries -- South Africa -- Eastern Cape Hamstring muscle -- Wounds and injuries -- South Africa -- Eastern Cape Black people -- Wounds and injuries -- South Africa -- Eastern Cape Fatigue
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5100 , http://hdl.handle.net/10962/d1001841
- Description: Background: Epidemiological findings indicate a higher risk of muscular thigh strain injury during the latter stages of both halves of soccer match-play, with muscular fatigue highlighted as a key etiological factor in injury causation. Anthropometric, biomechanical and physiological differences present in the Black African population may elicit unique thigh injury risk profiles, different from those of European and American players. Objectives: The purpose of the current research was to investigate the impact of soccer-specific fatigue on the risk of hamstring and quadricep injury in amateur Black African soccer players, in both the dominant and non-dominant legs. Methods: Participants were required to perform a soccer matchplay simulation (SAFT⁹⁰), consisting of multidirectional and utility movements, as well as frequent acceleration and deceleration. Selected physical, physiological and psychophysical responses were collected at specific time intervals throughout fatigue protocol performance. Results: Heart rate responses were observed to increase significantly (p<0.05) in response to the start of both halves, and remain elevated (but showing no further significant increase) during the performance of the remainder of the fatigue protocol. Significant (p<0.05) changes in both concentric and eccentric isokinetic variables of the knee flexors and extensors highlight the effect of muscular fatigue on performance in soccer match-play. Eccentric hamstring peak torque was observed to decrease significantly over time (60°.s⁻ₑ=17.34%, 180°.s⁻ₑ=18.27%), with significant reductions observed during both halves. The functional H:Q ratio at 180°.s⁻ₑ indicated a significant decrease over time (10.04%), with a significant decrease indicated during the second half of the SAFT⁹⁰ protocol. The passive half time interval did not result in significant changes in isokinetic variables. Isokinetic strength, work and power indicated no significant effects of leg dominance.. ‘Central’ and ‘Local’ ratings of exertion were observed to increase significantly (p<0.05) as a function of exercise duration. Conclusion: The overall reduction in both the eccentric hamstring peak torque and the functional strength ratio was illustrated to be similar to that of other soccer-specific fatigue research. As a result, the risk of thigh strain injuries is suggested to be similar regardless of playing level and race. These time dependent changes may have implications for competitive performance and increased predisposition to hamstring strain injuries during the latter stages of both halves of match-play
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- Date Issued: 2013
The jazz divas an analysis of the musical careers of six New Brighton vocalists
- Authors: Butete, Netsayi
- Date: 2012
- Subjects: Jazz musicians -- Research -- South Africa -- Port Elizabeth Ethnomusicology -- Research -- South Africa Sex discrimination against women -- South Africa Sex discrimination in employment -- South Africa Apartheid -- South Africa
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:2633 , http://hdl.handle.net/10962/d1002298
- Description: There has been insufficient academic research on the music of the Eastern Cape in general and Port Elizabeth and New Brighton in particular. This study, as part of the International Library of African Music (ILAM)lRed Location Museum Music History Project (ILAMIRLMHP) - an oral history intervention to save the music history of New Brighton from extinction through research and documentation of the memories of veteran musicians - is focused on jazz vocalists. The primary objective of my study is to investigate, critically analyze, interpret and document the career experiences of six New Brighton jazz vocalists in the context of performing in the Port Elizabeth music industry during the apartheid and the post-apartheid eras. The secondary objectives are to stimulate research interests in music students and ethnomusicologists to pursue research on the music of Port Elizabeth and the Eastern Cape and to inspire and motivate the vocalists to continue making music with renewed zeal. A qualitative research paradigm informed the field research necessary for this study. The fieldwork paved the way for an eclectic framework of analysis grounded in Pierre Bourdieu's notions of habitus, field and capital, examining the impact of the context on the vocalists' habitus which influenced how they viewed and interpreted their past and current experiences in the performance field. Data obtained through extensive interviewing of New Brighton's contemporary female vocalists and their male counterparts revealed that they have no opportunity to make commercial recordings. The musicians have to migrate to Johannesburg to have successful music careers, although personality politics, greed and lack of professionalism also work against the musicians' success. The data shows that New Brighton musicians, both male and female, do not have enough performance opportunities and there are fewer chances to tour now than there were from the 1960s through the 1980s. As in the apartheid era, female vocalists are still discriminated against in terms of pay, and men discriminate in how they pay other male musicians. Analysis of the vocalists' jazz compositions revealed that their song lyrics depict a bona fide urban African culture and reflect the emotional needs of the society in which they live.
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- Date Issued: 2012
Trade liberalisation, the real exchange rate and sectoral employment : a case study of South Africa
- Authors: Sibanda, Kin
- Date: 2016
- Subjects: Foreign exchange rates Employment (Economic theory) Free trade -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/12777 , vital:39360
- Description: This study examined the relationship between trade liberalisation, the real exchange rate and sectoral employment in South Africa for the period 1994 to 2014. Firstly, using quarterly time series data, the Autoregressive Distributed Lag (ARDL) technique was employed to formally check if South African real exchange rates are responsive to trade liberalisation. This was done to see if trade liberalisation impacts real exchange rates in South Africa, to the extent that they cannot be controlled concurrently in the subsequent models. Based on the ARDL results, trade liberalisation does not have a significant effect on the exchange rate. However, when the real exchange rate is an independent variable of trade liberalisation, the results show that real exchange rates affect trade, specifically the export propensity index. The next step was to assess the impact of trade liberalisation and real exchange rate on sectoral employment using quarterly panel data for South Africa from 1994 to 2014 controlling for both sector-specific and macro-economic variables. The study employed diverse panel data analysis techniques to separate the sectoral effects, starting with broad sectors followed by the disaggregated sectors, to identify the sectors most affected by real exchange rates and trade liberalisation. The Generalised method of Moments (GMM) results reveal that a unit increase in exchange rate (implying appreciation), causes employment to go down by about 9 percent in South Africa. The same relationship is depicted from the Pooled Mean Group (PMG) estimations in both the short run and long run. Random coefficients (betas) show that the real exchange rate negatively affects the primary and secondary sector with a positive but insignificant effect on the tertiary sector. The sub-sectors negatively hit hard by real exchange rates are communication, mining and transport. The results also show that trade liberalisation is linked to both job destruction and job creation. The static models reveal that trade openness has a statistically positive and significant impact on employment in the short run while the PMG estimator results show that the effect is negative and only significant in the short run. The dynamic models (GMM and PMG) showed trade liberalisation (as proxied by trade openness and import propensity) has a statistical and significantly positive short run impact on employment. This implies that selective trade liberalisation strategies are needed in order for South Africa to maximise the gains from trade.
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- Date Issued: 2016
Understanding educators' and learners' perceptions and experiences of their participation in Science Fairs/Expos : a South African case study.
- Authors: Kahenge, Wendelina Nambahu
- Date: 2014
- Subjects: Science fairs -- South Africa -- Grahamstown , Science -- Study and teaching -- South Africa -- Grahamstown , Vocational guidance -- South Africa -- Grahamstown , School children -- South Africa -- Attitudes , Teachers -- South Africa -- Attitudes , Teacher effectiveness -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1981 , http://hdl.handle.net/10962/d1013130
- Description: The rationale behind Science Expos is to develop and empower learners to be able to identify problems and find solutions (Eskom Expo Project Guide Book, 2013). It is believed that involvement in Science Expos arouses learners' interest to pursue science related careers. But despite these ideals, there is still poor participation in Science Expos by educators and learners. I conducted this case study in five schools in Grahamstown, Eastern Cape, South Africa. The purpose of this study was to understand educators' and learners' perceptions and experiences of their participation in Science Expos. The case study was designed within an interpretive paradigm. The data were generated, triangulated and validated by a variety of methods, namely, document analysis, interviews (semi-structured and focus group) and observations. The main findings of the study were that learners who participate in Science Expos attend workshops organised by Scifest and SAEON office with the help of some of the educators and lecturers from Rhodes University. Learners' participation was influenced and assisted by the educators and peers with whom they were able to communicate and share their projects with. It emerged from the study that, as a result of participating in Science Expos, educators (teachers) and learners were exposed to a wide variety of scientific investigations and skills that are necessary for their classroom based-scientific investigations. It also emerged from this study that educators and learners face the challenge of a lack of motivation; insufficient support from schools and parents; time constraints to support learners in their participation and a lack of knowledge among some educators on their learners' projects. Some learners are even discouraged from participating in Science Expos by their peers on the grounds that they have no chance of winning. Teachers therefore require continuous mentorship and capacity building in order to encourage their learners to partake.
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- Date Issued: 2014