Extending the matching facilities of Linda
- Wells, George C, Chalmer, A B, Clayton, Peter G
- Authors: Wells, George C , Chalmer, A B , Clayton, Peter G
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430452 , vital:72692 , https://doi.org/10.1007/3-540-46000-4_34
- Description: This paper discusses the associative matching mechanism used in the Linda coordination language for the retrieval of data. There are a number of problems with this mechanism which are discussed in the light of the requirements of applications using Linda. A number of solutions to these problems have been proposed. These are discussed and compared with a new approach to solving these problems. The benefits and the limitations of the new approach are considered, showing how it provides a considerable improvement in this area.
- Full Text:
- Date Issued: 2002
- Authors: Wells, George C , Chalmer, A B , Clayton, Peter G
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430452 , vital:72692 , https://doi.org/10.1007/3-540-46000-4_34
- Description: This paper discusses the associative matching mechanism used in the Linda coordination language for the retrieval of data. There are a number of problems with this mechanism which are discussed in the light of the requirements of applications using Linda. A number of solutions to these problems have been proposed. These are discussed and compared with a new approach to solving these problems. The benefits and the limitations of the new approach are considered, showing how it provides a considerable improvement in this area.
- Full Text:
- Date Issued: 2002
Extension theorems on L-topological spaces and L-fuzzy vector spaces
- Authors: Pinchuck, Andrew
- Date: 2002
- Subjects: Topology , Vector spaces , Generalized spaces
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5405 , http://hdl.handle.net/10962/d1005219 , Topology , Vector spaces , Generalized spaces
- Description: A non-trivial example of an L-topological space, the fuzzy real line is examined. Various L-topological properties and their relationships are developed. Extension theorems on the L-fuzzy real line as well as extension theorems on more general L-topological spaces follow. Finally, a theory of L-fuzzy vector spaces leads up to a fuzzy version of the Hahn-Banach theorem.
- Full Text:
- Date Issued: 2002
- Authors: Pinchuck, Andrew
- Date: 2002
- Subjects: Topology , Vector spaces , Generalized spaces
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5405 , http://hdl.handle.net/10962/d1005219 , Topology , Vector spaces , Generalized spaces
- Description: A non-trivial example of an L-topological space, the fuzzy real line is examined. Various L-topological properties and their relationships are developed. Extension theorems on the L-fuzzy real line as well as extension theorems on more general L-topological spaces follow. Finally, a theory of L-fuzzy vector spaces leads up to a fuzzy version of the Hahn-Banach theorem.
- Full Text:
- Date Issued: 2002
Finite element simulations of shear aggregation as a mechanism to form platinum group elements (PGEs) in dyke-like ore bodies
- Authors: Mbandezi, Mxolisi Louis
- Date: 2002
- Subjects: Platinum group , Magmas , Shear flow , Geophysics , Terrestrial heat flow
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5561 , http://hdl.handle.net/10962/d1018249
- Description: This research describes a two-dimensional modelling effort of heat and mass transport in simplified intrusive models of sills and their feeder dykes. These simplified models resembled a complex intrusive system such as the Great Dyke of Zimbabwe. This study investigated the impact of variable geometry to transport processes in two ways. First the time evolution of heat and mass transport during cooling was investigated. Then emphasis was placed on the application of convective scavenging as a mechanism that leads to the formation of minerals of economic interest, in particular the Platinum Group Elements (PGEs). The Navier-Stokes equations employed generated regions of high shear within the magma where we expected enhanced collisions between the immiscible sulphide liquid particles and PGEs. These collisions scavenge PGEs from the primary melt, aggregate and concentrate it to form PGEs enrichment in zero shear zones. The PGEs scavenge; concentrate and 'glue' in zero shear zones in the early history of convection because of viscosity and dispersive pressure (Bagnold effect). The effect of increasing the geometry size enhances scavenging, creates bigger zero shear zones with dilute concentrate of PGEs but you get high shear near the roots of the dyke/sill where the concentration will not be dilute. The time evolution calculations show that increasing the size of the magma chamber results in stronger initial convection currents for large magma models than for small ones. However, convection takes, approximately the same time to cease for both models. The research concludes that the time evolution for convective heat transfer is dependent on the viscosity rather than on geometry size. However, conductive heat transfer to the e-folding temperature was almost six times as long for the large model (M4) than the small one (M2). Variable viscosity as a physical property was applied to models 2 and 4 only. Video animations that simulate the cooling process for these models are enclosed in a CD at the back of this thesis. These simulations provide information with regard to the emplacement history and distribution of PGEs ore bodies. This will assist the reserve estimation and the location of economic minerals.
- Full Text:
- Date Issued: 2002
- Authors: Mbandezi, Mxolisi Louis
- Date: 2002
- Subjects: Platinum group , Magmas , Shear flow , Geophysics , Terrestrial heat flow
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5561 , http://hdl.handle.net/10962/d1018249
- Description: This research describes a two-dimensional modelling effort of heat and mass transport in simplified intrusive models of sills and their feeder dykes. These simplified models resembled a complex intrusive system such as the Great Dyke of Zimbabwe. This study investigated the impact of variable geometry to transport processes in two ways. First the time evolution of heat and mass transport during cooling was investigated. Then emphasis was placed on the application of convective scavenging as a mechanism that leads to the formation of minerals of economic interest, in particular the Platinum Group Elements (PGEs). The Navier-Stokes equations employed generated regions of high shear within the magma where we expected enhanced collisions between the immiscible sulphide liquid particles and PGEs. These collisions scavenge PGEs from the primary melt, aggregate and concentrate it to form PGEs enrichment in zero shear zones. The PGEs scavenge; concentrate and 'glue' in zero shear zones in the early history of convection because of viscosity and dispersive pressure (Bagnold effect). The effect of increasing the geometry size enhances scavenging, creates bigger zero shear zones with dilute concentrate of PGEs but you get high shear near the roots of the dyke/sill where the concentration will not be dilute. The time evolution calculations show that increasing the size of the magma chamber results in stronger initial convection currents for large magma models than for small ones. However, convection takes, approximately the same time to cease for both models. The research concludes that the time evolution for convective heat transfer is dependent on the viscosity rather than on geometry size. However, conductive heat transfer to the e-folding temperature was almost six times as long for the large model (M4) than the small one (M2). Variable viscosity as a physical property was applied to models 2 and 4 only. Video animations that simulate the cooling process for these models are enclosed in a CD at the back of this thesis. These simulations provide information with regard to the emplacement history and distribution of PGEs ore bodies. This will assist the reserve estimation and the location of economic minerals.
- Full Text:
- Date Issued: 2002
Formulation and assessment of monolithic beta blocker sustained release tablets prepared by direct compression
- Authors: Kieser, Leith Faye
- Date: 2002
- Subjects: Drugs -- Dosage forms , Drugs -- Administration , Pharmacology, Experimental , Adrenergic beta blockers , Tablets (Medicine) , Tableting , Neuropharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3764 , http://hdl.handle.net/10962/d1003242 , Drugs -- Dosage forms , Drugs -- Administration , Pharmacology, Experimental , Adrenergic beta blockers , Tablets (Medicine) , Tableting , Neuropharmacology
- Description: Beta blockers are commonly prescribed for the chronic treatment of hypertension, one of the most prolific disease states worldwide. The beta blockers selected for this study include acebutolol hydrochloride, labetalol hydrochloride, metoprolol tartrate oxprenolol hydrochloride and propranolol hydrochloride. All of these compounds have a short elimination half-life, necessitating multiple dose per day regimens and therefore the development of sustained release dosage forms incorporating these agents was considered beneficial in terms of extending the dosing interval, with the aim of improving patient compliance and subsequent therapeutic outcomes. Preformulation studies that were conducted included moisture content analysis by Karl Fischer titration, and DSC, a method used to predict potential interactions between the drugs and tablet excipients. Tablets were manufactured by both wet granulation and direct compression techniques, and the resultant drug release characteristics were evaluated using the USP Apparatus 3(BIO.DIS). A validated isocratic HPLC method, capable of separating the five drug candidates simultaneously, was developed and used for the analysis of drug samples. Tablet quality was assessed using analyses that included the physical assessment of weight, diameter, thickness, hardness and friability, as well as content uniformity of tablets, before and after dissolution testing. Direct compression tablet formulations containing each of the five beta blockers were successfully adapted from a prototype wet granulation matrix tablet containing metoprolol tartrate, and various formulation variables were investigated to establish,their effect on the rate and extent of drug release from these tablets. The grade and quantity of ethylcellulose used in the wet granulation and direct compression formulae influenced the release rate of some drug candidates. In addition, an alternative formulation method, involving freeze-drying of the drug with an ethylcellulose dispersion, was shown to have potential for altering release rates further. Anti-frictional agents, talc and colloidal silicon dioxide, did not affect drug release from these matrices,however, they affected the physical character:istics such as tablet weight and thickness, of the resultant tablets. All of the matrix tablets formulated were shown to release drug according to square root of time kinetics, in a sustained manner over a 22 hour period.
- Full Text:
- Date Issued: 2002
- Authors: Kieser, Leith Faye
- Date: 2002
- Subjects: Drugs -- Dosage forms , Drugs -- Administration , Pharmacology, Experimental , Adrenergic beta blockers , Tablets (Medicine) , Tableting , Neuropharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3764 , http://hdl.handle.net/10962/d1003242 , Drugs -- Dosage forms , Drugs -- Administration , Pharmacology, Experimental , Adrenergic beta blockers , Tablets (Medicine) , Tableting , Neuropharmacology
- Description: Beta blockers are commonly prescribed for the chronic treatment of hypertension, one of the most prolific disease states worldwide. The beta blockers selected for this study include acebutolol hydrochloride, labetalol hydrochloride, metoprolol tartrate oxprenolol hydrochloride and propranolol hydrochloride. All of these compounds have a short elimination half-life, necessitating multiple dose per day regimens and therefore the development of sustained release dosage forms incorporating these agents was considered beneficial in terms of extending the dosing interval, with the aim of improving patient compliance and subsequent therapeutic outcomes. Preformulation studies that were conducted included moisture content analysis by Karl Fischer titration, and DSC, a method used to predict potential interactions between the drugs and tablet excipients. Tablets were manufactured by both wet granulation and direct compression techniques, and the resultant drug release characteristics were evaluated using the USP Apparatus 3(BIO.DIS). A validated isocratic HPLC method, capable of separating the five drug candidates simultaneously, was developed and used for the analysis of drug samples. Tablet quality was assessed using analyses that included the physical assessment of weight, diameter, thickness, hardness and friability, as well as content uniformity of tablets, before and after dissolution testing. Direct compression tablet formulations containing each of the five beta blockers were successfully adapted from a prototype wet granulation matrix tablet containing metoprolol tartrate, and various formulation variables were investigated to establish,their effect on the rate and extent of drug release from these tablets. The grade and quantity of ethylcellulose used in the wet granulation and direct compression formulae influenced the release rate of some drug candidates. In addition, an alternative formulation method, involving freeze-drying of the drug with an ethylcellulose dispersion, was shown to have potential for altering release rates further. Anti-frictional agents, talc and colloidal silicon dioxide, did not affect drug release from these matrices,however, they affected the physical character:istics such as tablet weight and thickness, of the resultant tablets. All of the matrix tablets formulated were shown to release drug according to square root of time kinetics, in a sustained manner over a 22 hour period.
- Full Text:
- Date Issued: 2002
Foucauldian feminism: the implications of governmentality
- Macleod, Catriona I, Durrheim, Kevin
- Authors: Macleod, Catriona I , Durrheim, Kevin
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6261 , http://hdl.handle.net/10962/d1007879
- Description: Foucauldian discourse has been received with varying degrees of enthusiasm within feminist circles. Some authors (e.g. Balbus, 1988; Di Leonardo, 1991; Hartsock, 1990) see a Foucauldian stance as incompatible with feminist theory, while others (e.g. Grimshaw, 1993; Hoy, 1988; McNay, 1992; Sawicki, 1988) advocate a positive relationship between Foucauldian discourse and feminism. And then there are those theorists (e.g. Burman, 1990) who stand between these two positions, stating that while Foucault offers useful insights and methods to feminists, it can also be dangerous.
- Full Text:
- Date Issued: 2002
- Authors: Macleod, Catriona I , Durrheim, Kevin
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6261 , http://hdl.handle.net/10962/d1007879
- Description: Foucauldian discourse has been received with varying degrees of enthusiasm within feminist circles. Some authors (e.g. Balbus, 1988; Di Leonardo, 1991; Hartsock, 1990) see a Foucauldian stance as incompatible with feminist theory, while others (e.g. Grimshaw, 1993; Hoy, 1988; McNay, 1992; Sawicki, 1988) advocate a positive relationship between Foucauldian discourse and feminism. And then there are those theorists (e.g. Burman, 1990) who stand between these two positions, stating that while Foucault offers useful insights and methods to feminists, it can also be dangerous.
- Full Text:
- Date Issued: 2002
From conflict to negotiation: nature-based development on the South African Wild Coast. Special edition
- Palmer, Robin C G, Timmermans, Herman G, Fay, Derek
- Authors: Palmer, Robin C G , Timmermans, Herman G , Fay, Derek
- Date: 2002
- Language: English
- Type: Text
- Identifier: vital:543 , http://hdl.handle.net/10962/d1011730
- Description: The Rio Earth Summit of 1992 introduced several new approaches to environmental management under the general heading of sustainable development. One of these approaches has forced conservationists to concede that it is no longer feasible or ethical to exlude resident communities from protected areas, as had been the practice for more than a century. The alternative approach highlighting considerations of social justice and economic empowerment, is to recognise that humans are also part of the local ecology, and to find sustainable ways to maintain local livelihoods along with biodiversity. Especially in the global South, resource-dependant communities associated with protected areas had long been subjected to removals or restrictions by the state, and had been forced to modify livelihoods historically dependant on abundant natural resources, usually resulting in their acute impoverishment. Eastern and Southern Africa had been particulr sites of the former protectionist policies and their frequently tragic sequels for communities. Following the Summit much energy has been expended on finding sustainable alternatives to relocation in these regions, particularly new livelihoods linked to ecotourism From Conflict to Negotiation provides a South African case study of the shift from protectionism to sustainable development in the 1990's. Located on the wild coast of the Eastern Cape, Dwesa-Cwebe consists of a nature and marine reserve with eight adjacent resident communities that have historically depended on local forest, grassland and coastal resources. This are has been the focus of one of the earliest efforts in the 'new' South Africa to restore to the Xhosa-speaking residents ownership of the protected area from which they had been excluded for decades. Unusually the resident initiated the process. While others celebrated the advent of the new democracy in South Africa in 1994, the residents of this remote area, whose grieviences had been ignored during the political transition, planned a protest strategy featuring co-ordinated invasions of the protected area. The protest action succeeded to the extent that it gained massive media attention and provoked the special attention of national and regional goverment, non-govermental organizations (NGOs) and academic researchers. An early academic intervention designed to bring the residents and conservationists together was later expanded. Complementing the roles of goverment and NGOs, environmentalists and socio-cultural anthropologists, among others involved in this project, have attempted to address the conundrum of sustainable development policy implementation in a complex setting. From conflict to Negotiation details the findings of this pioneering research project. It is the story of local empowerment regained as confrontation yielded to negotiation and negotiation yielded co-management, local ownership and developmental partnerships. This landmark study will provoke ongoing discussion and research in an exciting new forum of community development.
- Full Text:
- Date Issued: 2002
- Authors: Palmer, Robin C G , Timmermans, Herman G , Fay, Derek
- Date: 2002
- Language: English
- Type: Text
- Identifier: vital:543 , http://hdl.handle.net/10962/d1011730
- Description: The Rio Earth Summit of 1992 introduced several new approaches to environmental management under the general heading of sustainable development. One of these approaches has forced conservationists to concede that it is no longer feasible or ethical to exlude resident communities from protected areas, as had been the practice for more than a century. The alternative approach highlighting considerations of social justice and economic empowerment, is to recognise that humans are also part of the local ecology, and to find sustainable ways to maintain local livelihoods along with biodiversity. Especially in the global South, resource-dependant communities associated with protected areas had long been subjected to removals or restrictions by the state, and had been forced to modify livelihoods historically dependant on abundant natural resources, usually resulting in their acute impoverishment. Eastern and Southern Africa had been particulr sites of the former protectionist policies and their frequently tragic sequels for communities. Following the Summit much energy has been expended on finding sustainable alternatives to relocation in these regions, particularly new livelihoods linked to ecotourism From Conflict to Negotiation provides a South African case study of the shift from protectionism to sustainable development in the 1990's. Located on the wild coast of the Eastern Cape, Dwesa-Cwebe consists of a nature and marine reserve with eight adjacent resident communities that have historically depended on local forest, grassland and coastal resources. This are has been the focus of one of the earliest efforts in the 'new' South Africa to restore to the Xhosa-speaking residents ownership of the protected area from which they had been excluded for decades. Unusually the resident initiated the process. While others celebrated the advent of the new democracy in South Africa in 1994, the residents of this remote area, whose grieviences had been ignored during the political transition, planned a protest strategy featuring co-ordinated invasions of the protected area. The protest action succeeded to the extent that it gained massive media attention and provoked the special attention of national and regional goverment, non-govermental organizations (NGOs) and academic researchers. An early academic intervention designed to bring the residents and conservationists together was later expanded. Complementing the roles of goverment and NGOs, environmentalists and socio-cultural anthropologists, among others involved in this project, have attempted to address the conundrum of sustainable development policy implementation in a complex setting. From conflict to Negotiation details the findings of this pioneering research project. It is the story of local empowerment regained as confrontation yielded to negotiation and negotiation yielded co-management, local ownership and developmental partnerships. This landmark study will provoke ongoing discussion and research in an exciting new forum of community development.
- Full Text:
- Date Issued: 2002
Fuel wood use in South Africa: Where to in the 21st Century?
- Williams, Anthony, Shackleton, Charlie M
- Authors: Williams, Anthony , Shackleton, Charlie M
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183026 , vital:43905 , xlink:href="https://doi.org/10.1080/20702620.2002.10434611"
- Description: South Africa is well known for the dichotomous nature of its economy, with its juxtaposed first and third world characteristics, perhaps nowhere more starkly evident than in the energy sector. South Africa produces and consumes over 60% of the total electrical energy on the African continent, and is ranked twelfth in the world in terms of carbon emissions (EIA, 2002). Yet the majority of the South African population does not have access to electricity, and despite the enormous strides taken since 1994 to increase household access to electricity (NER, 2001), newly electrified households, more often than not, cannot afford the appliances nor the monthly costs required to significantly improve their quality of life (White et al., 1997). Thus, most rural and many peri-urban households continue to use fuelwood as their primary energy source (Griffin et al., 1992; Dyer, 1996; Kotze, 1996; Williams et al., 1996). Fuelwood use presents both opportunities and risks.
- Full Text:
- Date Issued: 2002
- Authors: Williams, Anthony , Shackleton, Charlie M
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183026 , vital:43905 , xlink:href="https://doi.org/10.1080/20702620.2002.10434611"
- Description: South Africa is well known for the dichotomous nature of its economy, with its juxtaposed first and third world characteristics, perhaps nowhere more starkly evident than in the energy sector. South Africa produces and consumes over 60% of the total electrical energy on the African continent, and is ranked twelfth in the world in terms of carbon emissions (EIA, 2002). Yet the majority of the South African population does not have access to electricity, and despite the enormous strides taken since 1994 to increase household access to electricity (NER, 2001), newly electrified households, more often than not, cannot afford the appliances nor the monthly costs required to significantly improve their quality of life (White et al., 1997). Thus, most rural and many peri-urban households continue to use fuelwood as their primary energy source (Griffin et al., 1992; Dyer, 1996; Kotze, 1996; Williams et al., 1996). Fuelwood use presents both opportunities and risks.
- Full Text:
- Date Issued: 2002
Gender discourse and Malawian rural communities: a study of the meaning the people of traditional authority Likoswe of Chiradzulo make from human rights and gender messages
- Authors: Manda, Levi Zeleza
- Date: 2002
- Subjects: Human rights -- Malawi , Mass media in community development -- Malawi , Communication in community development -- Malawi , Mass media -- Social aspects -- Malawi , Mass media criticism -- Malawi , Women's rights -- Malawi , Sex role -- Malawi
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3456 , http://hdl.handle.net/10962/d1002910 , Human rights -- Malawi , Mass media in community development -- Malawi , Communication in community development -- Malawi , Mass media -- Social aspects -- Malawi , Mass media criticism -- Malawi , Women's rights -- Malawi , Sex role -- Malawi
- Description: Contrary to earlier beliefs and media theories such as the hypodermic needle or magic bullet, the audience of public communication is not a passive homogenous mass that easily succumbs to media influence. The audience is active, that is, it makes an effort to interpret media content. Depending on predisposing cultural, political, religious, or economic factors the audience makes different meanings from media texts. Media messages are not wholly controlled by producers, although the producers have their preferred and expected readings. Using qualitative research techniques associated with ethnographic and cultural studies (notably focus group discussions), this study sought to explore the meanings rural people in Malawi make out of human rights and gender messages broadcast on radio and through music. Interpreted against Stuart Hall's (1974b) Encoding and Decoding model, the study concludes that while rural communities understand and appreciate the new sociopolitical discourse, they take a negotiated stance because they have their own doubts and fears. They fear losing their cultural identity. Additionally, men, in particular, negotiate the messages because they fear losing their social power over land, property and family.
- Full Text:
- Date Issued: 2002
- Authors: Manda, Levi Zeleza
- Date: 2002
- Subjects: Human rights -- Malawi , Mass media in community development -- Malawi , Communication in community development -- Malawi , Mass media -- Social aspects -- Malawi , Mass media criticism -- Malawi , Women's rights -- Malawi , Sex role -- Malawi
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3456 , http://hdl.handle.net/10962/d1002910 , Human rights -- Malawi , Mass media in community development -- Malawi , Communication in community development -- Malawi , Mass media -- Social aspects -- Malawi , Mass media criticism -- Malawi , Women's rights -- Malawi , Sex role -- Malawi
- Description: Contrary to earlier beliefs and media theories such as the hypodermic needle or magic bullet, the audience of public communication is not a passive homogenous mass that easily succumbs to media influence. The audience is active, that is, it makes an effort to interpret media content. Depending on predisposing cultural, political, religious, or economic factors the audience makes different meanings from media texts. Media messages are not wholly controlled by producers, although the producers have their preferred and expected readings. Using qualitative research techniques associated with ethnographic and cultural studies (notably focus group discussions), this study sought to explore the meanings rural people in Malawi make out of human rights and gender messages broadcast on radio and through music. Interpreted against Stuart Hall's (1974b) Encoding and Decoding model, the study concludes that while rural communities understand and appreciate the new sociopolitical discourse, they take a negotiated stance because they have their own doubts and fears. They fear losing their cultural identity. Additionally, men, in particular, negotiate the messages because they fear losing their social power over land, property and family.
- Full Text:
- Date Issued: 2002
Genetic characterization of conspecific populations of Tilapia Sparrmanii (A.Smith 1840) in the dolomitic sinkholes and springs of the North-West Province (South Africa), and their comparison to Tilapia Guinasana (Trewavas 1936)
- Authors: Nxomani, Clifford David
- Date: 2002
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4079 , http://hdl.handle.net/10962/d1007452
- Description: This study was undertaken to investigate the genetic relationships of allopatric populations of the cichlid fish, Tilapia sparrmanii (A. Smith 1840) inhabiting the sinkholes and springs of the North West Province, South Africa. It also examined the genetic relationships of T sparrmanii to its polychromatic sister species, Tilapia guinasana (Trewavas 1936) which is endemic to the Guinas sinkhole in Namibia. Finally, the study investigated whether there is a genetic basis for T guinasana's colour polymorphism. The research was prompted by the concern of conservation authorities about the possible loss of unique fauna given the high demand for use of the subterranean waters for agricultural, domestic and industrial purposes. Such demands have the potential to drain these habitats. Further concerns related to habitat destruction and the introduction of alien species in the ecosystems inhabited by both fish species. Three approaches were adopted in attempting to answer the above questions. First was the investigation of Sodium dodecylsulphate (SDS)-Polyacrylamide Gel Electrophoresis (PAGE) of total cellular proteins as a fast and relatively inexpensive indicator of genetic relatedness between the fish populations. Secondly, genetic differentiation between the T sparrmanii populations and its relationship to T guinasana were assayed using restriction endonuclease analysis of Polymerase Chain Reaction (PCR)-amplified regions of the cytochrome b gene and the d-Ioop of mitochondrial DNA, coupled with Temperature Gradient Gel Electrophoresis (TGGE) analysis of the same regions. The third approach involved the use of Random Amplified Polymorphic DNA (RAPD) fingerprinting of the populations ofT sparrmanii as an indicator of genetic differentiation between them. RAPD fingerprinting was further used to investigate the genetic relationships between T sparrmanii and T guinasana and to probe the genetic basis of the polychromatism of the latter. SDS-PAGE did not reveal any genetic differentiation between the T sparrmanii populations, nor could the analysis detect variation within them. It however clearly distinguished at a species level between T sparrmanii and T guinasana as well as between these and other fish species, thus indicating its possible utility as an indicator of genetic relatedness at a species level. Mitochondrial studies employing the Restriction Fragment Length Polymorphism (RFLP) of Polymerase Chain Reaction (PCR)-amplified cytochrome b (1.1 kb) and d-Ioop regions (0.9 kb) with six and five restriction enzymes respectively, failed to reveal genetic differences within and between the allopatric populations. TGGE of500 bp of the d-Ioop and 400 bp of the 12sRNA PCR-amplified fragments did not reveal any differences between the populations of T. sparrmanii, nor did the analysis reveal any differences between T. sparrmanii and T. guinasana. The lack of differentiation between the T. sparrmanii populations by these mitochondrial Dna analysis techniques, despite habitat fragmentation, indicated a recent origin of the populations from a common ancestral population. Failure to distinguish between T. sparrmanii and T. guinasana may be related to the sensitivity of the techniques utilized. RAPD fingerprinting analysis indicated that the populations are genetically differentiated from each other. Using a measure of coefficient of variation, the population with the highest variation was the Wondergat population (13.99%), followed by the Klerkskraal popUlation (8.29%), the Malmani and Marico Oog populations (each with 5.88%) and the least variation (4.95 and 4.83%) was with the Amalinda and Molopo Oog populations respectively. This high degree of intra population similarity points to the fact that this differentiation is still confined within the limits of con specificity. The genetic distances between all of the T. sparrmanii populations across all primers ranged from 0.09 to 0.234 and averaged 0.146, a value that falls in the upper end of conspecific population differentiation. Such results indicate populational sub-division below the species level. RAPD fingerprinting therefore proved more sensitive than protein or mitochondrial studies. The differentiation it detected between the populations is a reflection of their adaptation to local conditions of the unique ecosystems they inhabit. A comparison with a subset of primers between T. guinasana and T. sparrmanii confirmed the separate species status of the former from the latter. The mean genetic distance between the T. sparrmanii populations was 0.136, compared to that between T. sparrmanii and T. guinasana which was found to be 0.374. Statistical analysis of the difference between the mean genetic distances indicated significance with 95% confidence. The polychromatism of T guinasana was investigated to determine whether there were significant differences between its five colour morphs. RAPD fingerprinting indicated with 95% confidence that there were significant differences between the colour forms based on the genetic distances computed between them. These genetic differences appeared to correlate with the observed assortative mating between the colour forms of the species. The manifestation of the polychromatism at sexual maturity in T guinasana probably indicates that colouration plays an important role in the breeding process. The genetic uniqueness shown here between the populations of T sparrmanii and the colour forms of T guinasana indicate for protective measures to be put in place if the genetic resources of the isolated fish populations are to be preserved. These must be coupled with a thorough assessment of the temporal and spatial distribution of genetic variability of the populations as a guide to a long-term management strategy for the fish populations and the ecosystems they inhabit. This study therefore has shown that the allopatric populations of T sparrmanii in the sinkholes and springs of the North-West Province are genetically unique, as well as show that the colour forms of T guinasana are genetically distinct.
- Full Text:
- Date Issued: 2002
- Authors: Nxomani, Clifford David
- Date: 2002
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4079 , http://hdl.handle.net/10962/d1007452
- Description: This study was undertaken to investigate the genetic relationships of allopatric populations of the cichlid fish, Tilapia sparrmanii (A. Smith 1840) inhabiting the sinkholes and springs of the North West Province, South Africa. It also examined the genetic relationships of T sparrmanii to its polychromatic sister species, Tilapia guinasana (Trewavas 1936) which is endemic to the Guinas sinkhole in Namibia. Finally, the study investigated whether there is a genetic basis for T guinasana's colour polymorphism. The research was prompted by the concern of conservation authorities about the possible loss of unique fauna given the high demand for use of the subterranean waters for agricultural, domestic and industrial purposes. Such demands have the potential to drain these habitats. Further concerns related to habitat destruction and the introduction of alien species in the ecosystems inhabited by both fish species. Three approaches were adopted in attempting to answer the above questions. First was the investigation of Sodium dodecylsulphate (SDS)-Polyacrylamide Gel Electrophoresis (PAGE) of total cellular proteins as a fast and relatively inexpensive indicator of genetic relatedness between the fish populations. Secondly, genetic differentiation between the T sparrmanii populations and its relationship to T guinasana were assayed using restriction endonuclease analysis of Polymerase Chain Reaction (PCR)-amplified regions of the cytochrome b gene and the d-Ioop of mitochondrial DNA, coupled with Temperature Gradient Gel Electrophoresis (TGGE) analysis of the same regions. The third approach involved the use of Random Amplified Polymorphic DNA (RAPD) fingerprinting of the populations ofT sparrmanii as an indicator of genetic differentiation between them. RAPD fingerprinting was further used to investigate the genetic relationships between T sparrmanii and T guinasana and to probe the genetic basis of the polychromatism of the latter. SDS-PAGE did not reveal any genetic differentiation between the T sparrmanii populations, nor could the analysis detect variation within them. It however clearly distinguished at a species level between T sparrmanii and T guinasana as well as between these and other fish species, thus indicating its possible utility as an indicator of genetic relatedness at a species level. Mitochondrial studies employing the Restriction Fragment Length Polymorphism (RFLP) of Polymerase Chain Reaction (PCR)-amplified cytochrome b (1.1 kb) and d-Ioop regions (0.9 kb) with six and five restriction enzymes respectively, failed to reveal genetic differences within and between the allopatric populations. TGGE of500 bp of the d-Ioop and 400 bp of the 12sRNA PCR-amplified fragments did not reveal any differences between the populations of T. sparrmanii, nor did the analysis reveal any differences between T. sparrmanii and T. guinasana. The lack of differentiation between the T. sparrmanii populations by these mitochondrial Dna analysis techniques, despite habitat fragmentation, indicated a recent origin of the populations from a common ancestral population. Failure to distinguish between T. sparrmanii and T. guinasana may be related to the sensitivity of the techniques utilized. RAPD fingerprinting analysis indicated that the populations are genetically differentiated from each other. Using a measure of coefficient of variation, the population with the highest variation was the Wondergat population (13.99%), followed by the Klerkskraal popUlation (8.29%), the Malmani and Marico Oog populations (each with 5.88%) and the least variation (4.95 and 4.83%) was with the Amalinda and Molopo Oog populations respectively. This high degree of intra population similarity points to the fact that this differentiation is still confined within the limits of con specificity. The genetic distances between all of the T. sparrmanii populations across all primers ranged from 0.09 to 0.234 and averaged 0.146, a value that falls in the upper end of conspecific population differentiation. Such results indicate populational sub-division below the species level. RAPD fingerprinting therefore proved more sensitive than protein or mitochondrial studies. The differentiation it detected between the populations is a reflection of their adaptation to local conditions of the unique ecosystems they inhabit. A comparison with a subset of primers between T. guinasana and T. sparrmanii confirmed the separate species status of the former from the latter. The mean genetic distance between the T. sparrmanii populations was 0.136, compared to that between T. sparrmanii and T. guinasana which was found to be 0.374. Statistical analysis of the difference between the mean genetic distances indicated significance with 95% confidence. The polychromatism of T guinasana was investigated to determine whether there were significant differences between its five colour morphs. RAPD fingerprinting indicated with 95% confidence that there were significant differences between the colour forms based on the genetic distances computed between them. These genetic differences appeared to correlate with the observed assortative mating between the colour forms of the species. The manifestation of the polychromatism at sexual maturity in T guinasana probably indicates that colouration plays an important role in the breeding process. The genetic uniqueness shown here between the populations of T sparrmanii and the colour forms of T guinasana indicate for protective measures to be put in place if the genetic resources of the isolated fish populations are to be preserved. These must be coupled with a thorough assessment of the temporal and spatial distribution of genetic variability of the populations as a guide to a long-term management strategy for the fish populations and the ecosystems they inhabit. This study therefore has shown that the allopatric populations of T sparrmanii in the sinkholes and springs of the North-West Province are genetically unique, as well as show that the colour forms of T guinasana are genetically distinct.
- Full Text:
- Date Issued: 2002
Geochemical constraints on coupled assimilation and fractional crystallization involving upper crustal compositions and continental tholeiitic magma
- Authors: Marsh, Julian S
- Date: 2002
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140432 , vital:37888 , https://doi.org/10.1016/0012-821X(89)90021-6
- Description: The commonly analyzed trace elements in tholeiites can be subdivided into three groups depending on their sense of enrichment or depletion in upper continental crust in relation to fractional crystallization. Lithophile incompatible elements are enriched in crustal rocks and by fractional crystallization, whereas compatible transition elements such as Ni and Cr are depleted. A small third group comprising Ti, V, Fe, and sometimes P, enrich with crystallization but are depleted in the crust.
- Full Text: false
- Date Issued: 2002
- Authors: Marsh, Julian S
- Date: 2002
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140432 , vital:37888 , https://doi.org/10.1016/0012-821X(89)90021-6
- Description: The commonly analyzed trace elements in tholeiites can be subdivided into three groups depending on their sense of enrichment or depletion in upper continental crust in relation to fractional crystallization. Lithophile incompatible elements are enriched in crustal rocks and by fractional crystallization, whereas compatible transition elements such as Ni and Cr are depleted. A small third group comprising Ti, V, Fe, and sometimes P, enrich with crystallization but are depleted in the crust.
- Full Text: false
- Date Issued: 2002
Geometric approximations towards free specular comic shading
- Winnemöller, Holger, Bangay, Shaun D
- Authors: Winnemöller, Holger , Bangay, Shaun D
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433453 , vital:72971 , https://doi.org/10.1111/1467-8659.00590
- Description: We extend the standard solution to comic rendering with a comic‐style specular component. To minimise the computational overhead associated with this extension, we introduce two optimising approximations; the perspective correction angle and the vertex face‐orientation measure. Both of these optimisations are generally applicable, but they are especially well suited for applications where a physically correct lighting simulation is not required. Using our optimisations we achieve performances comparable to the standard solution. As our approximations favour large models, we even outperform the standard approach for models consisting of 10,000 triangles or more, which we can render exceeding 40 frames per second, including the specular component.
- Full Text:
- Date Issued: 2002
- Authors: Winnemöller, Holger , Bangay, Shaun D
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433453 , vital:72971 , https://doi.org/10.1111/1467-8659.00590
- Description: We extend the standard solution to comic rendering with a comic‐style specular component. To minimise the computational overhead associated with this extension, we introduce two optimising approximations; the perspective correction angle and the vertex face‐orientation measure. Both of these optimisations are generally applicable, but they are especially well suited for applications where a physically correct lighting simulation is not required. Using our optimisations we achieve performances comparable to the standard solution. As our approximations favour large models, we even outperform the standard approach for models consisting of 10,000 triangles or more, which we can render exceeding 40 frames per second, including the specular component.
- Full Text:
- Date Issued: 2002
GIS in participatory catchment management : a case study in the Kat River Valley, Eastern Cape, South Africa
- Authors: McMaster, Alistair
- Date: 2002 , 2013-05-16
- Subjects: Watershed management -- South Africa -- Eastern Cape , Geographic information systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4868 , http://hdl.handle.net/10962/d1007602 , Watershed management -- South Africa -- Eastern Cape , Geographic information systems
- Description: In water resources management in South Africa, there is an emphasis on public participation. On a river catchment basis, one of the mechanisms for such participation is the establishment of catchment forums. However, members of catchment forums, particularly those coming from poor or rural communities, cannot be expected to engage in catchment management without having been enabled to do so. This thesis considers the use of GIS in the process of enabling the Kat River Valley Catchment Forum to better participate in catchment management. The research focus is on the use of GIS to facilitate an understanding of the Kat River Catchment and associated catchment concepts, and constructive communication and sharing, among the Catchment Forum. The GIS is used in the context of "GIS for Participatory Research", an outgrowth of Public Participation GIS (PPGIS), which focuses on GIS as a tool for empowerment within participatory processes. The study has used Action Research, situated in the Critical paradigm, as a methodology. The research has included seven Forum workshop processes and one series of in-village meetings. These engagements have involved map-based appraisals, issues and resource mapping, map-based planning, and the use of on-screen GIS for presentation and sharing. The use of GIS has facilitated the creation of customised maps, the integration of village-scale mapping into a catchment scale product, the presentation of synthesised data in digital and hardcopy format and, in so doing, has allowed catchment-scale appraisal. Outcomes enabling participation in catchment management have included developed mapping skills and an enhanced understanding of the catchment as a whole, and developed conceptual access to a decision-making language (or way of thinking), among participants. Furthermore, the Forum as a whole has identified common needs, and has developed a set of map-based action plans. The research process has yielded a number of lessons regarding "GIS for participation" and the participatory framework within which it takes place. Chief among these is that the GIS operator should take on the role of a participatory practitioner.
- Full Text:
- Date Issued: 2002
- Authors: McMaster, Alistair
- Date: 2002 , 2013-05-16
- Subjects: Watershed management -- South Africa -- Eastern Cape , Geographic information systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4868 , http://hdl.handle.net/10962/d1007602 , Watershed management -- South Africa -- Eastern Cape , Geographic information systems
- Description: In water resources management in South Africa, there is an emphasis on public participation. On a river catchment basis, one of the mechanisms for such participation is the establishment of catchment forums. However, members of catchment forums, particularly those coming from poor or rural communities, cannot be expected to engage in catchment management without having been enabled to do so. This thesis considers the use of GIS in the process of enabling the Kat River Valley Catchment Forum to better participate in catchment management. The research focus is on the use of GIS to facilitate an understanding of the Kat River Catchment and associated catchment concepts, and constructive communication and sharing, among the Catchment Forum. The GIS is used in the context of "GIS for Participatory Research", an outgrowth of Public Participation GIS (PPGIS), which focuses on GIS as a tool for empowerment within participatory processes. The study has used Action Research, situated in the Critical paradigm, as a methodology. The research has included seven Forum workshop processes and one series of in-village meetings. These engagements have involved map-based appraisals, issues and resource mapping, map-based planning, and the use of on-screen GIS for presentation and sharing. The use of GIS has facilitated the creation of customised maps, the integration of village-scale mapping into a catchment scale product, the presentation of synthesised data in digital and hardcopy format and, in so doing, has allowed catchment-scale appraisal. Outcomes enabling participation in catchment management have included developed mapping skills and an enhanced understanding of the catchment as a whole, and developed conceptual access to a decision-making language (or way of thinking), among participants. Furthermore, the Forum as a whole has identified common needs, and has developed a set of map-based action plans. The research process has yielded a number of lessons regarding "GIS for participation" and the participatory framework within which it takes place. Chief among these is that the GIS operator should take on the role of a participatory practitioner.
- Full Text:
- Date Issued: 2002
Growth and fruit production of Sclerocarya birrea in the South African lowveld
- Authors: Shackleton, Charlie M
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181618 , vital:43752 , xlink:href="https://doi.org/10.1023/A:1020579213024"
- Description: Sclerocarya birrea (A.Rich.) Hochst. subsp. caffra (Sond.) Kokwaro. is a common species throughout the semiarid, deciduous savannas of much of sub-Saharan Africa. It is a favoured species and is frequently maintained in homestead plots and arable fields in an agroforestry situation. Although the abundance and popularity of this species has led to several initiatives to commercialise a number of marula products, the sustainability of the resource base with respect to fruit production has not been considered. This paper reports on a field experiment that monitored growth rates and fruit production of a sample of adult trees from several wild populations. Mean fruit production was 36.8 kg per tree in the first year, and negligible in the second. This was considerably less than previous estimates, which were based largely on small samples or anecdotal reports. The maximum recorded yield was 416.6 kg per tree. Fruit production was positively related to the size of the tree. Growth rates of adult trees were slow. There was a strong positive relationship between mean annual diameter increment and stem diameter. The slow growth rates and low fruit yields indicate that more attention is required regarding the sustainability of there source and its ability to provide sufficient fruit for the growing subsistence and commercial demand at both local and national scales.
- Full Text:
- Date Issued: 2002
- Authors: Shackleton, Charlie M
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181618 , vital:43752 , xlink:href="https://doi.org/10.1023/A:1020579213024"
- Description: Sclerocarya birrea (A.Rich.) Hochst. subsp. caffra (Sond.) Kokwaro. is a common species throughout the semiarid, deciduous savannas of much of sub-Saharan Africa. It is a favoured species and is frequently maintained in homestead plots and arable fields in an agroforestry situation. Although the abundance and popularity of this species has led to several initiatives to commercialise a number of marula products, the sustainability of the resource base with respect to fruit production has not been considered. This paper reports on a field experiment that monitored growth rates and fruit production of a sample of adult trees from several wild populations. Mean fruit production was 36.8 kg per tree in the first year, and negligible in the second. This was considerably less than previous estimates, which were based largely on small samples or anecdotal reports. The maximum recorded yield was 416.6 kg per tree. Fruit production was positively related to the size of the tree. Growth rates of adult trees were slow. There was a strong positive relationship between mean annual diameter increment and stem diameter. The slow growth rates and low fruit yields indicate that more attention is required regarding the sustainability of there source and its ability to provide sufficient fruit for the growing subsistence and commercial demand at both local and national scales.
- Full Text:
- Date Issued: 2002
Growth patterns of Pterocarpus angolensis in savannas of the South African lowveld
- Authors: Shackleton, Charlie M
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182373 , vital:43824 , xlink:href="https://doi.org/10.1016/S0378-1127(01)00676-4"
- Description: Pterocarpus angolensis D.C. is one of the most valuable indigenous timber species on the African continent south of the equator. Because of its high value, it is actively sought after in a number of countries, and wild populations are diminishing. However, attempts at artificial germination and growth trials have yielded poor results, thus, emphasis needs to be placed on sustainable management of existing populations. Success of in situ management will be enhanced if based on reliable data and knowledge regarding the growth patterns of this species within specific localities and countries. Such comprehensive data are lacking for several countries, including South Africa. This paper presents empirical data on a number of studies investigating the growth patterns of P. angolensis in the central lowveld savannas of South Africa, including phenology, annual diameter increment, size class structure, size of reproductive maturity, and morphometric relationships. The size class profile indicated that there was adequate recruitment of P. angolensis, but with constricted through growth from the suffrutex stage to the sapling stage. A small proportion of individuals attained reproductive maturity at 8 cm diameter, but most were bigger. All stems were reproductively mature by 26 cm diameter. This is below the minimum size for harvesting which is dictated by the need for a well developed heartwood. Annual growth was strongly related to stem size and rainfall during the growing season. Basal area increment of small stems was approximately four times greater than mature stems, and declined with increasing stem size. Over the 6-year-period and across all stem sizes, mean diameter increment was 4.5 mm per year. This rate is towards the lower end of the range of reported growth rates from other countries, and poses particular challenges for the sustainable management of this species in South African savannas.
- Full Text:
- Date Issued: 2002
- Authors: Shackleton, Charlie M
- Date: 2002
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182373 , vital:43824 , xlink:href="https://doi.org/10.1016/S0378-1127(01)00676-4"
- Description: Pterocarpus angolensis D.C. is one of the most valuable indigenous timber species on the African continent south of the equator. Because of its high value, it is actively sought after in a number of countries, and wild populations are diminishing. However, attempts at artificial germination and growth trials have yielded poor results, thus, emphasis needs to be placed on sustainable management of existing populations. Success of in situ management will be enhanced if based on reliable data and knowledge regarding the growth patterns of this species within specific localities and countries. Such comprehensive data are lacking for several countries, including South Africa. This paper presents empirical data on a number of studies investigating the growth patterns of P. angolensis in the central lowveld savannas of South Africa, including phenology, annual diameter increment, size class structure, size of reproductive maturity, and morphometric relationships. The size class profile indicated that there was adequate recruitment of P. angolensis, but with constricted through growth from the suffrutex stage to the sapling stage. A small proportion of individuals attained reproductive maturity at 8 cm diameter, but most were bigger. All stems were reproductively mature by 26 cm diameter. This is below the minimum size for harvesting which is dictated by the need for a well developed heartwood. Annual growth was strongly related to stem size and rainfall during the growing season. Basal area increment of small stems was approximately four times greater than mature stems, and declined with increasing stem size. Over the 6-year-period and across all stem sizes, mean diameter increment was 4.5 mm per year. This rate is towards the lower end of the range of reported growth rates from other countries, and poses particular challenges for the sustainable management of this species in South African savannas.
- Full Text:
- Date Issued: 2002
Heal my heart: stories of hurt and healing from group therapy
- Authors: Knight, Zelda G
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6263 , http://hdl.handle.net/10962/d1007881
- Description: This paper records four stories that emerged from four group therapy members. These stories are stories of fundamentally broken hearts. I utilise this material to address two psychological phenomena in group therapy - self-disclosure and the corrective emotional experience. The overarching theoretical framework is the existential approach to group therapy, and the underlying theoretical assumptions of relational psychoanalysis applied to group therapy. In the context of the material I present several theoretical points. Some of the chief points are the notion of the "in-between-ness of healing" and the importance of two processes in healing - i) the process of telling the story (remembering) in such as way that it is relived both emotionally and physically, and ii) followed closely by a corrective emotional experience. The emphasis in this paper is that remembering and reliving in therapy is not enough and a corrective emotional experience is required. Broadening this perspective of the healing mechanism of a corrective emotional experience, a principle argument of this paper is that the therapeutic action in group therapy (as it can be in individual therapy) is not insight but a new relationship.
- Full Text:
- Date Issued: 2002
- Authors: Knight, Zelda G
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6263 , http://hdl.handle.net/10962/d1007881
- Description: This paper records four stories that emerged from four group therapy members. These stories are stories of fundamentally broken hearts. I utilise this material to address two psychological phenomena in group therapy - self-disclosure and the corrective emotional experience. The overarching theoretical framework is the existential approach to group therapy, and the underlying theoretical assumptions of relational psychoanalysis applied to group therapy. In the context of the material I present several theoretical points. Some of the chief points are the notion of the "in-between-ness of healing" and the importance of two processes in healing - i) the process of telling the story (remembering) in such as way that it is relived both emotionally and physically, and ii) followed closely by a corrective emotional experience. The emphasis in this paper is that remembering and reliving in therapy is not enough and a corrective emotional experience is required. Broadening this perspective of the healing mechanism of a corrective emotional experience, a principle argument of this paper is that the therapeutic action in group therapy (as it can be in individual therapy) is not insight but a new relationship.
- Full Text:
- Date Issued: 2002
Heterologous expression of the helicoverpa armigera stunt virus in Saccharomyces cerevisiae
- Authors: Venter, Philip Arno
- Date: 2002
- Subjects: Helicoverpa armigera Saccharomyces cerevisiae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3895 , http://hdl.handle.net/10962/d1003811
- Description: Lepidopteran insects like Helicoverpa armigera, more commonly known as the cotton bollworm, are economically important pests of a wide variety of crops throughout the world. The Helicoverpa armigera stunt virus (HaSV), a tetravirus with a bipartite single-stranded positive-sense RNA genome, has great potential as a biological pesticide against H. armigera. The larger genomic strand of this virus (RNA1) encodes the viral replicase, while the other (RNA2) encodes the 71 kDa capsid protein precursor (p71). 240 copies of p71 assemble into a procapsid with the concomitant encapsidation of the viral RNA. This is followed by a complex maturation event that is characterized by the autoproteolytic cleavage of p71 into the 64 kDa capsid protein (P64) and a 7 kDa peptide (p7). The rearrangements that occur during maturation results in the formation of mature HaSV capsids that can thereupon deliver RNA to other susceptible host cells. The principal objective of the research described in this study was to demonstrate that this virus could be assembled in Saccharomyces cerevisiae. S. cerevisiae expression vectors were constructed for the production of p71. This protein was detected in cell lysates from two different strains of S. cerevisiae, both containing either chromosomal or episomal copies of an expression cassette for P71. A number of factors relating to the expression of P71 (e.g. strains used, expression loci and expression rate) and the preparation of protein extracts from S. cerevisiae (e.g. the presence of various protease inhibitors and salt concentrations) were examined to attain optimal levels of soluble p71. A small fraction of the optimized soluble p71 was shown to be in the form of virus-like particles (VLPs), with a yield of ≤10⁷ VLPs from a 1.5l culture of P71⁺ cells. These particles were exclusively in the procapsid form, had a similar buoyant density to that of wild-type HaSV and could undergo maturation when the pH was reduced to 5. S. cerevisiae vectors were constructed for the episomal expression of the HaSV genomic RNAs. These vectors directed the transcription of RNA1 and RNA2 transcripts, which had similar sizes to those of the HaSV genomic RNAs. Mature HaSV particles were purified from cells, transgenic for P71, RNA1 and RNA2, by way of two different virus purification protocols that were developed during this study. RT-PCR analyses on RNA-extracts from these particles demonstrated that RNA transcripts, which were produced in trans with p71, could be encapsidated by HaSV capsids in S. cerevisiae. A droplet-feed bioassay on H. armigera larvae demonstrated that the S. cerevisiae-derived HaSV particles caused impaired larval development. This response was correlated with the detection of HaSV RNA2 in RNA extractions from larvae that were used in this bioassay. The results that were generated through the course of this study, provided proof for the concept of the non-host production of infectious HaSV particles from S. cerevisiae. This work could serve as a foundation for future research on the development of an expression system for the large-scale production of this virus as a biopesticide.
- Full Text:
- Date Issued: 2002
- Authors: Venter, Philip Arno
- Date: 2002
- Subjects: Helicoverpa armigera Saccharomyces cerevisiae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3895 , http://hdl.handle.net/10962/d1003811
- Description: Lepidopteran insects like Helicoverpa armigera, more commonly known as the cotton bollworm, are economically important pests of a wide variety of crops throughout the world. The Helicoverpa armigera stunt virus (HaSV), a tetravirus with a bipartite single-stranded positive-sense RNA genome, has great potential as a biological pesticide against H. armigera. The larger genomic strand of this virus (RNA1) encodes the viral replicase, while the other (RNA2) encodes the 71 kDa capsid protein precursor (p71). 240 copies of p71 assemble into a procapsid with the concomitant encapsidation of the viral RNA. This is followed by a complex maturation event that is characterized by the autoproteolytic cleavage of p71 into the 64 kDa capsid protein (P64) and a 7 kDa peptide (p7). The rearrangements that occur during maturation results in the formation of mature HaSV capsids that can thereupon deliver RNA to other susceptible host cells. The principal objective of the research described in this study was to demonstrate that this virus could be assembled in Saccharomyces cerevisiae. S. cerevisiae expression vectors were constructed for the production of p71. This protein was detected in cell lysates from two different strains of S. cerevisiae, both containing either chromosomal or episomal copies of an expression cassette for P71. A number of factors relating to the expression of P71 (e.g. strains used, expression loci and expression rate) and the preparation of protein extracts from S. cerevisiae (e.g. the presence of various protease inhibitors and salt concentrations) were examined to attain optimal levels of soluble p71. A small fraction of the optimized soluble p71 was shown to be in the form of virus-like particles (VLPs), with a yield of ≤10⁷ VLPs from a 1.5l culture of P71⁺ cells. These particles were exclusively in the procapsid form, had a similar buoyant density to that of wild-type HaSV and could undergo maturation when the pH was reduced to 5. S. cerevisiae vectors were constructed for the episomal expression of the HaSV genomic RNAs. These vectors directed the transcription of RNA1 and RNA2 transcripts, which had similar sizes to those of the HaSV genomic RNAs. Mature HaSV particles were purified from cells, transgenic for P71, RNA1 and RNA2, by way of two different virus purification protocols that were developed during this study. RT-PCR analyses on RNA-extracts from these particles demonstrated that RNA transcripts, which were produced in trans with p71, could be encapsidated by HaSV capsids in S. cerevisiae. A droplet-feed bioassay on H. armigera larvae demonstrated that the S. cerevisiae-derived HaSV particles caused impaired larval development. This response was correlated with the detection of HaSV RNA2 in RNA extractions from larvae that were used in this bioassay. The results that were generated through the course of this study, provided proof for the concept of the non-host production of infectious HaSV particles from S. cerevisiae. This work could serve as a foundation for future research on the development of an expression system for the large-scale production of this virus as a biopesticide.
- Full Text:
- Date Issued: 2002
Identification and analysis of the factors that influence the development of female entrepreneurs in the informal sector
- Authors: Sokabo, Nobenguni B
- Date: 2002
- Subjects: Women-owned business enterprises -- South Africa , Small business -- South Africa , Businesswomen -- South Africa , Women in development -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:10907 , http://hdl.handle.net/10948/98 , Women-owned business enterprises -- South Africa , Small business -- South Africa , Businesswomen -- South Africa , Women in development -- South Africa
- Description: There is a remarkable increase in the participation of females in business activities due to their involvement in the informal sector. These activities appear to be insignificant and not measurable because they are outside the regulatory framework, but they also absorb multitudes of the unemployable. Notwithstanding the challenges of low levels of education, lack of skills and finance as well as the need to balance reproductive and productive roles, females are under pressure to generate income through trading in small scale businesses that can hardly grow beyond subsistence level. With the meagre earnings from their activities, they ensure the survival of their families. If female entrepreneurs are developed and brought into the economic main stream, they will bring with them their unique survivalist techniques that will contribute towards economic development and growth in the country. This report examines the constraints that affect the development of female entrepreneurs in the informal sector.
- Full Text:
- Date Issued: 2002
- Authors: Sokabo, Nobenguni B
- Date: 2002
- Subjects: Women-owned business enterprises -- South Africa , Small business -- South Africa , Businesswomen -- South Africa , Women in development -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:10907 , http://hdl.handle.net/10948/98 , Women-owned business enterprises -- South Africa , Small business -- South Africa , Businesswomen -- South Africa , Women in development -- South Africa
- Description: There is a remarkable increase in the participation of females in business activities due to their involvement in the informal sector. These activities appear to be insignificant and not measurable because they are outside the regulatory framework, but they also absorb multitudes of the unemployable. Notwithstanding the challenges of low levels of education, lack of skills and finance as well as the need to balance reproductive and productive roles, females are under pressure to generate income through trading in small scale businesses that can hardly grow beyond subsistence level. With the meagre earnings from their activities, they ensure the survival of their families. If female entrepreneurs are developed and brought into the economic main stream, they will bring with them their unique survivalist techniques that will contribute towards economic development and growth in the country. This report examines the constraints that affect the development of female entrepreneurs in the informal sector.
- Full Text:
- Date Issued: 2002
Identification of Cowdria ruminantium proteins that induce specific cellular immune responses
- Authors: Van Kleef, Mirinda
- Date: 2002
- Subjects: Ruminants--Pathogens Heartwater
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4061 , http://hdl.handle.net/10962/d1004373
- Description: Cowdria ruminantium (Cowdria) is an obligate intracellular pathogen that causes heartwater in ruminants. Cellular immunity and the type I cytokine IFN-γ have been implicated in protective immunity to heartwater. The aim of this thesis was to identify proteins of the Welgevonden isolate of Cowdria that induce lymphocyte proliferation and IFN-γ production. Differential centrifugation was found to be the simplest and most efficient method of Cowdria purification. Cowdria organisms were fractionated into their constituent proteins of between 11 and 168 kDa by continuous flow electrophoresis. The resulting fractions were tested for their ability to stimulate lymphocyte proliferation in vitro. In an attempt to simulate the natural infective process, peripheral blood mononuclear cells (PBMC) were obtained from two cattle rendered immune by infection and treatment and assayed in proliferation assays with the proteins fractions. In a parallel study, four cattle were immunised with inactivated Cowdria to determine whether their lymphocytes responded similarly. Cowdria-specific proliferation was detected for only a brief period after immunisation by infection with live organisms. This response was only detected again two to three years later. In contrast, PBMC from animals immunised with inactivated organisms were continuously responsive for at least three years. Only Cowdria proteins with molecular masses of 11, 12, 14 to 17 and 19 to 23 kDa induced proliferative responses in PBMC obtained from all six animals. Cell surface phenotypic analysis of Cowdria specific T-cell lines indicated that CD4⁺ lymphocytes were enriched over time with a concomitant increase in antigen-specific proliferation and IFN-γ production. Proteins of molecular masses 13 to 18 kDa induced CD4⁺ lymphocyte proliferation and IFN-γ production by T-cell lines from all the animals tested. Antibodies raised in a chicken and in rabbits to these low molecular weight proteins had low titres and specificity. Two-dimensional electrophoresis indicated that proteins within a single molecular weight range comprised several components with different pIs, revealing the complexity of the Cowdria proteome. This complicates the search for potentially protective antigens. Nevertheless, since they cause proliferation and IFN-γ production by lymphocytes from immunised cattle, these low molecular weight proteins merit further investigation as potential vaccine antigens. , Author: Mirinda van Kleef neé Rossouw
- Full Text:
- Date Issued: 2002
- Authors: Van Kleef, Mirinda
- Date: 2002
- Subjects: Ruminants--Pathogens Heartwater
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4061 , http://hdl.handle.net/10962/d1004373
- Description: Cowdria ruminantium (Cowdria) is an obligate intracellular pathogen that causes heartwater in ruminants. Cellular immunity and the type I cytokine IFN-γ have been implicated in protective immunity to heartwater. The aim of this thesis was to identify proteins of the Welgevonden isolate of Cowdria that induce lymphocyte proliferation and IFN-γ production. Differential centrifugation was found to be the simplest and most efficient method of Cowdria purification. Cowdria organisms were fractionated into their constituent proteins of between 11 and 168 kDa by continuous flow electrophoresis. The resulting fractions were tested for their ability to stimulate lymphocyte proliferation in vitro. In an attempt to simulate the natural infective process, peripheral blood mononuclear cells (PBMC) were obtained from two cattle rendered immune by infection and treatment and assayed in proliferation assays with the proteins fractions. In a parallel study, four cattle were immunised with inactivated Cowdria to determine whether their lymphocytes responded similarly. Cowdria-specific proliferation was detected for only a brief period after immunisation by infection with live organisms. This response was only detected again two to three years later. In contrast, PBMC from animals immunised with inactivated organisms were continuously responsive for at least three years. Only Cowdria proteins with molecular masses of 11, 12, 14 to 17 and 19 to 23 kDa induced proliferative responses in PBMC obtained from all six animals. Cell surface phenotypic analysis of Cowdria specific T-cell lines indicated that CD4⁺ lymphocytes were enriched over time with a concomitant increase in antigen-specific proliferation and IFN-γ production. Proteins of molecular masses 13 to 18 kDa induced CD4⁺ lymphocyte proliferation and IFN-γ production by T-cell lines from all the animals tested. Antibodies raised in a chicken and in rabbits to these low molecular weight proteins had low titres and specificity. Two-dimensional electrophoresis indicated that proteins within a single molecular weight range comprised several components with different pIs, revealing the complexity of the Cowdria proteome. This complicates the search for potentially protective antigens. Nevertheless, since they cause proliferation and IFN-γ production by lymphocytes from immunised cattle, these low molecular weight proteins merit further investigation as potential vaccine antigens. , Author: Mirinda van Kleef neé Rossouw
- Full Text:
- Date Issued: 2002
Identifying the need for the development of an instrument to determine senior phase teachers' science-assessment competence
- Authors: Lombard, Elsa Helena
- Date: 2002
- Subjects: Science -- Ability testing -- South Africa , Science -- Study and teaching -- South Africa -- Port Elizabeth -- Evaluation , Educational tests and measurements -- South Africa , Competency-based education -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10786 , http://hdl.handle.net/10948/100 , Science -- Ability testing -- South Africa , Science -- Study and teaching -- South Africa -- Port Elizabeth -- Evaluation , Educational tests and measurements -- South Africa , Competency-based education -- South Africa
- Description: The focus of this study is the competences expected of teachers in the senior phase to assess the Natural Sciences learning area. In order to be in line with the new developments, the South African science teacher will need relevant assessment training in order to utilise appropriate techniques that are in line with the new educational philosophy. The question arises: What competences do teachers need for assessing science in the senior phase? An ethnographic case study was implemented as research methodology in the descriptive research paradigm. The investigation comprised observing the classroom practices of a sample of three senior phase science teachers in two primary schools and in one secondary school in the Port Elizabeth region. The data obtained from the observations were triangulated with related artefacts produced by both the teachers and the learners in each case. In order to establish these expected competences a document analysis was done from a selection of South African documents. The descriptions of the real life assessment practices of the sample of science teachers were then compared with the competences expected by the South African education system. The comparison between the real-life assessment practices and the expected practices concurred with Shepard’s (2000, p.12) belief that the abilities needed to implement classroom assessment “are daunting”. The classroom-based assessment practices of the sample of teachers revealed a variety of assessment beliefs, practices and competence. The needs of these teachers are so diversified and intense that individualised professional development is needed if sustained implementation of the new curriculum and accompanying assessment competences is to be facilitated. The research established the need to develop an instrument that the science teachers can use to assess their own competence. There should be training modules drawn up in line with this instrument. Teachers should be able to choose the professional development modules that would address their own unique needs
- Full Text:
- Date Issued: 2002
- Authors: Lombard, Elsa Helena
- Date: 2002
- Subjects: Science -- Ability testing -- South Africa , Science -- Study and teaching -- South Africa -- Port Elizabeth -- Evaluation , Educational tests and measurements -- South Africa , Competency-based education -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10786 , http://hdl.handle.net/10948/100 , Science -- Ability testing -- South Africa , Science -- Study and teaching -- South Africa -- Port Elizabeth -- Evaluation , Educational tests and measurements -- South Africa , Competency-based education -- South Africa
- Description: The focus of this study is the competences expected of teachers in the senior phase to assess the Natural Sciences learning area. In order to be in line with the new developments, the South African science teacher will need relevant assessment training in order to utilise appropriate techniques that are in line with the new educational philosophy. The question arises: What competences do teachers need for assessing science in the senior phase? An ethnographic case study was implemented as research methodology in the descriptive research paradigm. The investigation comprised observing the classroom practices of a sample of three senior phase science teachers in two primary schools and in one secondary school in the Port Elizabeth region. The data obtained from the observations were triangulated with related artefacts produced by both the teachers and the learners in each case. In order to establish these expected competences a document analysis was done from a selection of South African documents. The descriptions of the real life assessment practices of the sample of science teachers were then compared with the competences expected by the South African education system. The comparison between the real-life assessment practices and the expected practices concurred with Shepard’s (2000, p.12) belief that the abilities needed to implement classroom assessment “are daunting”. The classroom-based assessment practices of the sample of teachers revealed a variety of assessment beliefs, practices and competence. The needs of these teachers are so diversified and intense that individualised professional development is needed if sustained implementation of the new curriculum and accompanying assessment competences is to be facilitated. The research established the need to develop an instrument that the science teachers can use to assess their own competence. There should be training modules drawn up in line with this instrument. Teachers should be able to choose the professional development modules that would address their own unique needs
- Full Text:
- Date Issued: 2002
Imaging the metaphysical in contemporary art practice : a comparative study of intertextuality, poststructuralism and metaphysical symbolism
- Authors: Opperman, J. A.
- Date: 2002
- Subjects: Mind and body , Metaphysics in art
- Language: English
- Type: Thesis , Masters , MTech (Fine Art, Painting)
- Identifier: vital:10762 , http://hdl.handle.net/10948/101 , Mind and body , Metaphysics in art
- Description: It was then that I decided to investigate how contemporary forms of metaphysical imaging have evolved formally and stylistically. I began to question how such approaches might be informed by current philosophical thought, given that many contemporary theorists have adopted a sceptical view towards metaphysical discourse. This point of contention presented me with the initial challenge of finding an artist whose exploration of metaphysical content is supported by topical philosophical thought. I intended this inquiry to serve as a basis from which to develop my own approach to imaging metaphysical content and to situate it within the context of contemporary thought.
- Full Text:
- Date Issued: 2002
- Authors: Opperman, J. A.
- Date: 2002
- Subjects: Mind and body , Metaphysics in art
- Language: English
- Type: Thesis , Masters , MTech (Fine Art, Painting)
- Identifier: vital:10762 , http://hdl.handle.net/10948/101 , Mind and body , Metaphysics in art
- Description: It was then that I decided to investigate how contemporary forms of metaphysical imaging have evolved formally and stylistically. I began to question how such approaches might be informed by current philosophical thought, given that many contemporary theorists have adopted a sceptical view towards metaphysical discourse. This point of contention presented me with the initial challenge of finding an artist whose exploration of metaphysical content is supported by topical philosophical thought. I intended this inquiry to serve as a basis from which to develop my own approach to imaging metaphysical content and to situate it within the context of contemporary thought.
- Full Text:
- Date Issued: 2002