Apartheid South Africa's foreign relations with African states, 1961-1994
- Authors: Pfister, Roger
- Date: 2004
- Subjects: Apartheid -- South Africa -- History -- 20th century Government, Resistance to -- South Africa Democracy -- South Africa South Africa -- Politics and government -- 20th century South Africa -- History -- 1961-1994 South Africa -- Foreign relations -- Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2863 , http://hdl.handle.net/10962/d1007632
- Description: This thesis examines South Africa's foreign relations, viewed from a South African perspective, with the black African countries beyond southern Africa from 1961 to 1994. These relations were determined by the conflict between Pretoria's apartheid ideology on the one hand, and African continental rejection of South Africa's race discrimination policies and its exclusion from the community of African states on the other. The documentary material used primarily stems from the Department of Foreign Affairs archive in Pretoria, supplemented by research conducted in other archives. Furthermore, we conducted interviews and correspondence, and consulted the relevant primary and secondary literature. Given the main source of information, we chose to make this work a case study in Diplomatic History. In consequence, and constituting the core of the study, Chapters 3 to 6 explore the interaction between South Africa and the black African states in a chronological order. At the same time, we draw on the analytical concepts from the academic disciplines of Political Science and its derivative, International Relations, to comprehend developments more fully. We discuss the significance of the approaches from these two disciplines in both the Introduction and Chapter 2. In particular, we emphasise that this study is about Pretoria's foreign policy, involving state and non-state actors, and we suggest that the unequal status between South Africa and the other African states constitutes an inherent factor in the relationship between them. The Conclusion examines the role of the state and non-state actors in determining Pretoria's foreign relations and the relevance of the structural imbalance between South Africa and the black African states in this context.
- Full Text:
- Date Issued: 2004
- Authors: Pfister, Roger
- Date: 2004
- Subjects: Apartheid -- South Africa -- History -- 20th century Government, Resistance to -- South Africa Democracy -- South Africa South Africa -- Politics and government -- 20th century South Africa -- History -- 1961-1994 South Africa -- Foreign relations -- Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2863 , http://hdl.handle.net/10962/d1007632
- Description: This thesis examines South Africa's foreign relations, viewed from a South African perspective, with the black African countries beyond southern Africa from 1961 to 1994. These relations were determined by the conflict between Pretoria's apartheid ideology on the one hand, and African continental rejection of South Africa's race discrimination policies and its exclusion from the community of African states on the other. The documentary material used primarily stems from the Department of Foreign Affairs archive in Pretoria, supplemented by research conducted in other archives. Furthermore, we conducted interviews and correspondence, and consulted the relevant primary and secondary literature. Given the main source of information, we chose to make this work a case study in Diplomatic History. In consequence, and constituting the core of the study, Chapters 3 to 6 explore the interaction between South Africa and the black African states in a chronological order. At the same time, we draw on the analytical concepts from the academic disciplines of Political Science and its derivative, International Relations, to comprehend developments more fully. We discuss the significance of the approaches from these two disciplines in both the Introduction and Chapter 2. In particular, we emphasise that this study is about Pretoria's foreign policy, involving state and non-state actors, and we suggest that the unequal status between South Africa and the other African states constitutes an inherent factor in the relationship between them. The Conclusion examines the role of the state and non-state actors in determining Pretoria's foreign relations and the relevance of the structural imbalance between South Africa and the black African states in this context.
- Full Text:
- Date Issued: 2004
Variability in and coupling of larval availability and settlement of the mussel Perna perna : a spatio-temporal approach
- Authors: Porri, Francesca
- Date: 2004
- Subjects: Mussels -- South Africa Perna -- South Africa Perna -- Spawning Perna -- Larvae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5796 , http://hdl.handle.net/10962/d1005484
- Description: Population dynamics of many intertidal organisms are highly influenced by the abundance and distribution of planktonic larvae in the water column and their arrival on the shore. The brown mussel, Perna perna was used to investigate two of the primary processes that affect population size and dynamics, larval availability and settlement, on the south coast of South Africa. Perna perna is a dominant species on rocky shores of the southern and eastern coasts of South Africa. It creates three-dimensional beds that provide habitats for many other species and hence promotes biodiversity. Larval availability and settlement were examined at different spatial and temporal scales using a nested experimental design. To detect possible relationships between larval availability and settlement, the studies were simultaneous. Two sites, 4km apart, were chosen to investigate mussel settlement patterns. Within each site, three locations (300m from each other) were selected. At each location, five artificial settler collectors were placed at approximately 20cm intervals. Collectors were replaced at a range of time intervals, from daily to seasonal, for 16 months. Each intertidal location was paired with an offshore station, 500m from the shore, where larval availability was measured. At each offshore station, three vertical hauls were collected twice a month using a plankton net. Plankton sampling lasted for 14 months and was designed to examine variability on three temporal scales: seasonal, lunar and daily. The results showed no correlation between the distribution of larvae in the water and settlers on the shore. While larvae were abundant in the water at the start of sampling, they became very rare throughout the rest of the study at both sites and all locations. In contrast, distinct peaks of settler abundance were observed during the seasonal settlement study. In addition to the expected, strong temporal variation that emerged from both studies at all time scales, spatial patterns of variability were also observed. While no spatial effect was detected for the larvae in the water column, there was distinct spatial variation in settlement at the location level: some locations always showed higher settlement than others. These results suggest that, on scales of hundreds of meters to kilometers, larval availability and settlement are very unpredictable in time and that differential delivery of larvae occurs from nearshore waters to the shore. Although the effect of the state of the moon (new or full) was not significant in either study, more settlers seemed to arrive on the shore during new moon. Wind direction did not correlate significantly with settlement. However, the dropping of offshore winds and the prevalence of onshore winds, which are characteristic of summer, may be linked to the start of settlement. Nevertheless, further investigations on tidal or lunar cycles and on the influence of wind on surface currents are required to clarify the effects of moon and wind on settlement.
- Full Text:
- Date Issued: 2004
- Authors: Porri, Francesca
- Date: 2004
- Subjects: Mussels -- South Africa Perna -- South Africa Perna -- Spawning Perna -- Larvae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5796 , http://hdl.handle.net/10962/d1005484
- Description: Population dynamics of many intertidal organisms are highly influenced by the abundance and distribution of planktonic larvae in the water column and their arrival on the shore. The brown mussel, Perna perna was used to investigate two of the primary processes that affect population size and dynamics, larval availability and settlement, on the south coast of South Africa. Perna perna is a dominant species on rocky shores of the southern and eastern coasts of South Africa. It creates three-dimensional beds that provide habitats for many other species and hence promotes biodiversity. Larval availability and settlement were examined at different spatial and temporal scales using a nested experimental design. To detect possible relationships between larval availability and settlement, the studies were simultaneous. Two sites, 4km apart, were chosen to investigate mussel settlement patterns. Within each site, three locations (300m from each other) were selected. At each location, five artificial settler collectors were placed at approximately 20cm intervals. Collectors were replaced at a range of time intervals, from daily to seasonal, for 16 months. Each intertidal location was paired with an offshore station, 500m from the shore, where larval availability was measured. At each offshore station, three vertical hauls were collected twice a month using a plankton net. Plankton sampling lasted for 14 months and was designed to examine variability on three temporal scales: seasonal, lunar and daily. The results showed no correlation between the distribution of larvae in the water and settlers on the shore. While larvae were abundant in the water at the start of sampling, they became very rare throughout the rest of the study at both sites and all locations. In contrast, distinct peaks of settler abundance were observed during the seasonal settlement study. In addition to the expected, strong temporal variation that emerged from both studies at all time scales, spatial patterns of variability were also observed. While no spatial effect was detected for the larvae in the water column, there was distinct spatial variation in settlement at the location level: some locations always showed higher settlement than others. These results suggest that, on scales of hundreds of meters to kilometers, larval availability and settlement are very unpredictable in time and that differential delivery of larvae occurs from nearshore waters to the shore. Although the effect of the state of the moon (new or full) was not significant in either study, more settlers seemed to arrive on the shore during new moon. Wind direction did not correlate significantly with settlement. However, the dropping of offshore winds and the prevalence of onshore winds, which are characteristic of summer, may be linked to the start of settlement. Nevertheless, further investigations on tidal or lunar cycles and on the influence of wind on surface currents are required to clarify the effects of moon and wind on settlement.
- Full Text:
- Date Issued: 2004
The enzymology of enhanced hydrolysis within the biosulphidogenic recycling sludge bed reactor (RSBR)
- Authors: Enongene, Godlove Nkwelle
- Date: 2004
- Subjects: Hydrolysis , Sewage sludge , Sewage -- Purification -- Anaerobic treatment , Water -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4132 , http://hdl.handle.net/10962/d1015744
- Description: The hydrolysis of complex organic heteropolymers contained in municipal wastewater to simpler monomers by extracellular hydrolytic enzymes is generally considered the rate-limiting step of the biodegradation process. Previous studies of the Recycling Sludge Bed Reactor (RSBR) revealed that the hydrolysis of complex particulate organics, such as those contained in primary sludge (PS), was enhanced under anaerobic biosulphidogenic conditions. Although the mechanism was not fully understood, it appeared to involve the interaction of sulfide and sludge flocs. The current study was conducted using a 3500 ml laboratory-scale RSBR fed sieved PS at a loading rate of 0.5 kg COD/m³.day and an initial chemical oxygen demand (COD) to sulfate ratio (COD:SO₄) of 1:1. There was no significant accumulation of undigested sludge in the reactor over the 60-day experimental period and the quantity of SO₄ reduced indicated that the yield of soluble products from PS was at least as high as those reported previously for this system (> 50%). In the current study, the specific activities of a range of extracellular hydrolytic enzymes (L-alanine aminopeptidase, L-leucine aminopeptidase, arylsulphatase, α-glucosidase, β- glucosidase, protease and lipase) were monitored in a sulfide gradient within a biosulphidogenic RSBR. Data obtained indicated that the specific enzymatic activities increased with the depth of the RSBR and also correlated with a number of the physicochemical parameters including sulfide, alkalinity and sulfate. The activities of α- glucosidase and β-glucosidase were higher than that of the other enzymes studied. Lipase activity was relatively low and studies conducted on the enzyme-enzyme interaction using specific enzyme inhibitors indicated that lipases were probably being digested by the proteases. Further studies to determine the impact of sulfide on the enzymes, showed an increase in the enzyme activity with increasing sulfide concentration. Possible direct affects were investigated by looking for changes in the Michaelis constant (Km) and the maximal velocity (Vmax) of the crude enzymes with varying sulfide concentrations (250, 400 and 500 mg/l) using natural and synthetic substrates. The results showed no significant difference in both the Km and the Vmax for any of the hydrolytic enzymes except for the protease. The latter showed a statistically significant increase in the Km with increasing sulfide concentration. Although this indicated a direct interaction, this difference was not large enough to be of biochemical significance and was consequently not solely responsible for the enhanced hydrolysis observed in the RSBR. Investigation into the floc characteristics indicated that the biosulphidogenic RSBR flocs were generally small in size and became more dendritic with the depth of the RSBR. Based on the above data, the previously proposed descriptive models of enhanced hydrolysis of particulate organic matter in a biosulphidogenic RSBR has been revised. It is thought that the effect of sulfide on the hydrolysis step is primarily indirect and that the reduction in floc size and alteration of the floc shape to a more dendritic form is central to the success of the process.
- Full Text:
- Date Issued: 2004
- Authors: Enongene, Godlove Nkwelle
- Date: 2004
- Subjects: Hydrolysis , Sewage sludge , Sewage -- Purification -- Anaerobic treatment , Water -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4132 , http://hdl.handle.net/10962/d1015744
- Description: The hydrolysis of complex organic heteropolymers contained in municipal wastewater to simpler monomers by extracellular hydrolytic enzymes is generally considered the rate-limiting step of the biodegradation process. Previous studies of the Recycling Sludge Bed Reactor (RSBR) revealed that the hydrolysis of complex particulate organics, such as those contained in primary sludge (PS), was enhanced under anaerobic biosulphidogenic conditions. Although the mechanism was not fully understood, it appeared to involve the interaction of sulfide and sludge flocs. The current study was conducted using a 3500 ml laboratory-scale RSBR fed sieved PS at a loading rate of 0.5 kg COD/m³.day and an initial chemical oxygen demand (COD) to sulfate ratio (COD:SO₄) of 1:1. There was no significant accumulation of undigested sludge in the reactor over the 60-day experimental period and the quantity of SO₄ reduced indicated that the yield of soluble products from PS was at least as high as those reported previously for this system (> 50%). In the current study, the specific activities of a range of extracellular hydrolytic enzymes (L-alanine aminopeptidase, L-leucine aminopeptidase, arylsulphatase, α-glucosidase, β- glucosidase, protease and lipase) were monitored in a sulfide gradient within a biosulphidogenic RSBR. Data obtained indicated that the specific enzymatic activities increased with the depth of the RSBR and also correlated with a number of the physicochemical parameters including sulfide, alkalinity and sulfate. The activities of α- glucosidase and β-glucosidase were higher than that of the other enzymes studied. Lipase activity was relatively low and studies conducted on the enzyme-enzyme interaction using specific enzyme inhibitors indicated that lipases were probably being digested by the proteases. Further studies to determine the impact of sulfide on the enzymes, showed an increase in the enzyme activity with increasing sulfide concentration. Possible direct affects were investigated by looking for changes in the Michaelis constant (Km) and the maximal velocity (Vmax) of the crude enzymes with varying sulfide concentrations (250, 400 and 500 mg/l) using natural and synthetic substrates. The results showed no significant difference in both the Km and the Vmax for any of the hydrolytic enzymes except for the protease. The latter showed a statistically significant increase in the Km with increasing sulfide concentration. Although this indicated a direct interaction, this difference was not large enough to be of biochemical significance and was consequently not solely responsible for the enhanced hydrolysis observed in the RSBR. Investigation into the floc characteristics indicated that the biosulphidogenic RSBR flocs were generally small in size and became more dendritic with the depth of the RSBR. Based on the above data, the previously proposed descriptive models of enhanced hydrolysis of particulate organic matter in a biosulphidogenic RSBR has been revised. It is thought that the effect of sulfide on the hydrolysis step is primarily indirect and that the reduction in floc size and alteration of the floc shape to a more dendritic form is central to the success of the process.
- Full Text:
- Date Issued: 2004
Capsule immobilisation of sulphate-reducing bacteria and application in disarticulated systems
- Authors: Sanyahumbi, Douglas
- Date: 2004
- Subjects: Sulfur bacteria , Water -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3935 , http://hdl.handle.net/10962/d1003994
- Description: Biotechnology of sulphate reducing bacteria has developed rapidly in recent years with the recognition of their extensive and diverse biocatalytic potential. However, their application in a number of areas has been constrained due to problems including poor cell retention within the continuous bioprocess reactor environment, and contamination of the treated stream with residual organic feed components and cell biomass. These problems have so far excluded the application of biological sulphate reduction in the treatment of ‘clean’ inorganic waste streams where components such as sulphate, acidity and heavy metal contamination require treatment. This study investigated the effective immobilisation of sulphate reducing bacterial cultures and proposed that the disarticulation of the electron donor and carbon source supply using such systems would create the basis for their application in the treatment of ‘clean’ inorganic waste streams. A functional and stable sulphate reducing culture was selected and following evaluation using a number of techniques, was immobilised by encapsulation within a calcium-alginate-xanthum gum membrane to give robust capsules with good sulphate reduction activity. The concept of disarticulation was investigated in a swing-back cycle where the carbon source was excluded and the electron donor supplied in the form of hydrogen gas in a continuous up-flow capsule-packed column reactor. Following a period of operation in this mode (4-12 days), the system was swung back to a carbon feed to supply requirements of cell maintenance (2-3 days). Three types of synthetic ‘clean’ inorganic waste stream treatments were investigated, including sulphate removal, neutralisation of acidity and heavy metal (copper and lead) removal. The results showed: • Sulphate removal at a rate of 50 mg SO₄²⁻L/day/g initial wet mass of capsules during three 4-day cycles of electron donor phase. This was comparable to the performance of free cell systems; • Neutralisation of acidity where influent pH values of 2.4 and 4.0 were elevated to above pH 7.5; • Copper removal of 99 and 85 % was achieved with initial copper concentrations of 2 and 60 mg/L respectively; • Percentage lead removal values of 49 and 78 % were achieved; This first report on the application of the concept of capsular immobilisation and disarticulation in the treatment of ‘clean’ inorganic waste streams will require future studies in order to extend the development of the full potential of the concept.
- Full Text:
- Date Issued: 2004
- Authors: Sanyahumbi, Douglas
- Date: 2004
- Subjects: Sulfur bacteria , Water -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3935 , http://hdl.handle.net/10962/d1003994
- Description: Biotechnology of sulphate reducing bacteria has developed rapidly in recent years with the recognition of their extensive and diverse biocatalytic potential. However, their application in a number of areas has been constrained due to problems including poor cell retention within the continuous bioprocess reactor environment, and contamination of the treated stream with residual organic feed components and cell biomass. These problems have so far excluded the application of biological sulphate reduction in the treatment of ‘clean’ inorganic waste streams where components such as sulphate, acidity and heavy metal contamination require treatment. This study investigated the effective immobilisation of sulphate reducing bacterial cultures and proposed that the disarticulation of the electron donor and carbon source supply using such systems would create the basis for their application in the treatment of ‘clean’ inorganic waste streams. A functional and stable sulphate reducing culture was selected and following evaluation using a number of techniques, was immobilised by encapsulation within a calcium-alginate-xanthum gum membrane to give robust capsules with good sulphate reduction activity. The concept of disarticulation was investigated in a swing-back cycle where the carbon source was excluded and the electron donor supplied in the form of hydrogen gas in a continuous up-flow capsule-packed column reactor. Following a period of operation in this mode (4-12 days), the system was swung back to a carbon feed to supply requirements of cell maintenance (2-3 days). Three types of synthetic ‘clean’ inorganic waste stream treatments were investigated, including sulphate removal, neutralisation of acidity and heavy metal (copper and lead) removal. The results showed: • Sulphate removal at a rate of 50 mg SO₄²⁻L/day/g initial wet mass of capsules during three 4-day cycles of electron donor phase. This was comparable to the performance of free cell systems; • Neutralisation of acidity where influent pH values of 2.4 and 4.0 were elevated to above pH 7.5; • Copper removal of 99 and 85 % was achieved with initial copper concentrations of 2 and 60 mg/L respectively; • Percentage lead removal values of 49 and 78 % were achieved; This first report on the application of the concept of capsular immobilisation and disarticulation in the treatment of ‘clean’ inorganic waste streams will require future studies in order to extend the development of the full potential of the concept.
- Full Text:
- Date Issued: 2004
An investigation into how marketers cope with an environment of high complexity and turbulence, with special reference to the South African environment
- Authors: Mason, Roger Bruce
- Date: 2004
- Subjects: Marketing -- South Africa , Success in business -- South Africa , Industrial management -- South Africa , Organizational change -- South Africa , Chaotic behavior in systems , Complexity (Philosophy)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:752 , http://hdl.handle.net/10962/d1003873 , Marketing -- South Africa , Success in business -- South Africa , Industrial management -- South Africa , Organizational change -- South Africa , Chaotic behavior in systems , Complexity (Philosophy)
- Description: This study investigated relationships between marketing success, the level of external environmental complexity and turbulence, and marketing mix tactics. The literature suggested that more successful companies in simple and stable environments use stabilising marketing tactics, while more successful companies in complex and turbulent environments use destabilising tactics, regardless of industry habits, management preferences or market sector. A marketing mix model for the different environments was developed using a chaos and complexity theory perspective. The study was exploratory, using a qualitative, case study technique. Data was collected via depth interviews and document analysis from four companies in the information technology (IT) and packaging industries. These industries were identified as, respectively, the most complex and turbulent, and the simplest and most stable, South African environments. Two companies from each industry were chosen to reflect more successful and less successful companies. The more successful company in the complex/turbulent environment was found to use destabilising tactics, as did the more successful company in the simple/stable environment. Therefore, contrary to expectations, it appears that destabilising tactics contribute more to success than stabilising tactics do, regardless of the environment. It was also found, contrary to expectations, that stabilising tactics were used by both the less successful companies. The research concluded that destabilising tactics are related to more success and stabilising tactics to less success. The lack of clear differentiation between the two industries may be because the whole South African environment is complex and turbulent, because the packaging industry is not sufficiently simple and stable to differentiate it from the IT industry or because packaging industry managers perceive their industry to be complex and turbulent and act accordingly. Despite these uncertainties, the research showed the marketing mix model to be reasonably accurate for the complex/turbulent environment, and therefore of potential value to South African companies. To overcome the equivocal findings, further research is recommended in different industries, in countries with different levels of complexity and turbulence and into specific marketing mix tactics. Research into managers’ perceptions of environmental complexity and turbulence and into co-evolution of marketing tactics and external environments would also be of value.
- Full Text:
- Date Issued: 2004
- Authors: Mason, Roger Bruce
- Date: 2004
- Subjects: Marketing -- South Africa , Success in business -- South Africa , Industrial management -- South Africa , Organizational change -- South Africa , Chaotic behavior in systems , Complexity (Philosophy)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:752 , http://hdl.handle.net/10962/d1003873 , Marketing -- South Africa , Success in business -- South Africa , Industrial management -- South Africa , Organizational change -- South Africa , Chaotic behavior in systems , Complexity (Philosophy)
- Description: This study investigated relationships between marketing success, the level of external environmental complexity and turbulence, and marketing mix tactics. The literature suggested that more successful companies in simple and stable environments use stabilising marketing tactics, while more successful companies in complex and turbulent environments use destabilising tactics, regardless of industry habits, management preferences or market sector. A marketing mix model for the different environments was developed using a chaos and complexity theory perspective. The study was exploratory, using a qualitative, case study technique. Data was collected via depth interviews and document analysis from four companies in the information technology (IT) and packaging industries. These industries were identified as, respectively, the most complex and turbulent, and the simplest and most stable, South African environments. Two companies from each industry were chosen to reflect more successful and less successful companies. The more successful company in the complex/turbulent environment was found to use destabilising tactics, as did the more successful company in the simple/stable environment. Therefore, contrary to expectations, it appears that destabilising tactics contribute more to success than stabilising tactics do, regardless of the environment. It was also found, contrary to expectations, that stabilising tactics were used by both the less successful companies. The research concluded that destabilising tactics are related to more success and stabilising tactics to less success. The lack of clear differentiation between the two industries may be because the whole South African environment is complex and turbulent, because the packaging industry is not sufficiently simple and stable to differentiate it from the IT industry or because packaging industry managers perceive their industry to be complex and turbulent and act accordingly. Despite these uncertainties, the research showed the marketing mix model to be reasonably accurate for the complex/turbulent environment, and therefore of potential value to South African companies. To overcome the equivocal findings, further research is recommended in different industries, in countries with different levels of complexity and turbulence and into specific marketing mix tactics. Research into managers’ perceptions of environmental complexity and turbulence and into co-evolution of marketing tactics and external environments would also be of value.
- Full Text:
- Date Issued: 2004
An analysis of the censorship of popular music within the context of cultural struggle in South Africa during the 1980s
- Authors: Drewett, Michael
- Date: 2004
- Subjects: Censorship -- South Africa Popular music -- Censorship -- South Africa Popular music -- Censorship -- South Africa -- History Popular music -- Social aspects -- South Africa Popular music -- Political aspects -- South Africa Popular music -- South Africa -- History and criticism Protest songs -- South Africa -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3350 , http://hdl.handle.net/10962/d1007098
- Description: The censorship of popular music in South Africa during the 1980s severely affected South African musicians. The apartheid government was directly involved in centralized state censorship by means of the Directorate of Publications, while the South African Broadcasting Corporation exercised government censorship at the level of airplay. Others who assisted state censorship included religious and cultural interest groups. State censorship in turn put pressure on record companies, musicians and others to practice self-censorship. Many musicians who overtly sang about taboo topics or who used controversial language subsequently experienced censorship in different forms, including police harassment. Musicians were also subject to anti-apartheid forms of censorship,such as the United Nations endorsed cultural boycott. Not all instances of censorship were overtly political, but they were always framed by, and took place within, a repressive legal-political system. This thesis found that despite the state's attempt to maintain its hegemony, musicians sought ways of overcoming censorship practices. It is argued that the ensuing struggle cannot be conceived of in simple binary terms. The works of Antonio Gramsci, Michel Foucault and Pierre Bourdieu, in particular, are applied to the South African context in exploring the localized nuances of the cultural struggle over music censorship. It is argued that fragmented resistance to censorship arose out of the very censorship structures that attempted to silence musicians. Textual analysis brought to light that resistance took various forms including songs with provocative lyrics and titles, and more subtle means of bypassing censorship, including the use of symbolism, camouflaged lyrics, satire and crossover performance. Musicians were faced with the challenge of bypassing censors yet nevertheless conveying their message to an audience. The most successful cases negotiated censorial practices while getting an apparent message across to a wide audience. Broader forms of resistance were also explored, including opposition through live performance, counter-hegemonic information on record covers, resistance from exile, alignment with political organizations and legal challenges to state censorship. In addition, some record companies developed strategies of resistance to censorship. The many innovative practices outlined in this thesis demonstrate that even in the context of constraint, resistance is possible. Despite censorship, South African musicians were able to express themselves through approaching their music in an innovative way.
- Full Text:
- Date Issued: 2004
- Authors: Drewett, Michael
- Date: 2004
- Subjects: Censorship -- South Africa Popular music -- Censorship -- South Africa Popular music -- Censorship -- South Africa -- History Popular music -- Social aspects -- South Africa Popular music -- Political aspects -- South Africa Popular music -- South Africa -- History and criticism Protest songs -- South Africa -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3350 , http://hdl.handle.net/10962/d1007098
- Description: The censorship of popular music in South Africa during the 1980s severely affected South African musicians. The apartheid government was directly involved in centralized state censorship by means of the Directorate of Publications, while the South African Broadcasting Corporation exercised government censorship at the level of airplay. Others who assisted state censorship included religious and cultural interest groups. State censorship in turn put pressure on record companies, musicians and others to practice self-censorship. Many musicians who overtly sang about taboo topics or who used controversial language subsequently experienced censorship in different forms, including police harassment. Musicians were also subject to anti-apartheid forms of censorship,such as the United Nations endorsed cultural boycott. Not all instances of censorship were overtly political, but they were always framed by, and took place within, a repressive legal-political system. This thesis found that despite the state's attempt to maintain its hegemony, musicians sought ways of overcoming censorship practices. It is argued that the ensuing struggle cannot be conceived of in simple binary terms. The works of Antonio Gramsci, Michel Foucault and Pierre Bourdieu, in particular, are applied to the South African context in exploring the localized nuances of the cultural struggle over music censorship. It is argued that fragmented resistance to censorship arose out of the very censorship structures that attempted to silence musicians. Textual analysis brought to light that resistance took various forms including songs with provocative lyrics and titles, and more subtle means of bypassing censorship, including the use of symbolism, camouflaged lyrics, satire and crossover performance. Musicians were faced with the challenge of bypassing censors yet nevertheless conveying their message to an audience. The most successful cases negotiated censorial practices while getting an apparent message across to a wide audience. Broader forms of resistance were also explored, including opposition through live performance, counter-hegemonic information on record covers, resistance from exile, alignment with political organizations and legal challenges to state censorship. In addition, some record companies developed strategies of resistance to censorship. The many innovative practices outlined in this thesis demonstrate that even in the context of constraint, resistance is possible. Despite censorship, South African musicians were able to express themselves through approaching their music in an innovative way.
- Full Text:
- Date Issued: 2004
'Environmental policy to community action': methodology and approaches in community-based environmental education programmes in Uganda
- Authors: Babikwa, Daniel J
- Date: 2004
- Subjects: Environmental education -- Uganda -- Case studies Education and state -- Uganda Community development -- Uganda -- Case studies Sustainable development -- Uganda -- Case studies Environmental policy -- Uganda -- Case studies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1518 , http://hdl.handle.net/10962/d1003400
- Description: This research was conducted in Luwero, a rural district in central Uganda, over a period of three years, half of which entailed fulltime engagement in a participatory action research process with VEDCO, an indigenous NGO. The study focuses on the educational processes involved in the translation of Uganda's environmental policy into action at community level. It looks at community-based education and development activities run by VEDCO among smallholder farmers. The study addressed four objectives. For the first objective I developed a conceptual framework through a review of theories informing education in general and environmental education, adult education, community education, and community development in particular. The second objective was to conduct a situational analysis to identify contextual issues related to policy implementation at community level. The third objective was to engage in a participatory action research process with the NGO in the farming community in response to the identified contextual issues, and the fourth was to explore and comment on environmental education methods used within a community context. PRA techniques, interviews, and other participatory data collection methods were used to generate the data. The study reveals contradictions that limit NGO capacity to make appropriate use of participatory education processes in implementing policy-related training at community level. Elements in the National Plan for the Modernisation of Agriculture, for example, conflicted with the principle of sustainable development underlying the policy. VEDCO itself was changing from a social-welfare-oriented organisation into a commercial enterprise pursuing economic goals, which conflicted with its social goals. The capitalist development ideology of the donor was being adopted by VEDCO, which contradicted the goals of people-centred development. This was exacerbated by VEDCO's dependency on donor funds for its activities. Contextual issues like people's history; poverty, gender and inconsistent land policies further complicated the policy implementation processes. There were also inconsistencies in the epistemological assumptions and didactic approaches evident in the implementation. The study shows that the intended emancipatory education processes are more often supplanted by technicist methodologies. Thus, it exposes the underlying historical, ideological and epistemological tensions and contradictions within the field of education, particularly in relation to the `paradigmatic' orientations (neo-classical, liberal and socially critical/emancipatory) outlined in the literature. Conclusions are made at two levels: in relation to the study goals, of examining policy implementation at community level and in terms of the study's contribution to the understanding of current education theory in the context of sustainable development among communities.
- Full Text:
- Date Issued: 2004
- Authors: Babikwa, Daniel J
- Date: 2004
- Subjects: Environmental education -- Uganda -- Case studies Education and state -- Uganda Community development -- Uganda -- Case studies Sustainable development -- Uganda -- Case studies Environmental policy -- Uganda -- Case studies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1518 , http://hdl.handle.net/10962/d1003400
- Description: This research was conducted in Luwero, a rural district in central Uganda, over a period of three years, half of which entailed fulltime engagement in a participatory action research process with VEDCO, an indigenous NGO. The study focuses on the educational processes involved in the translation of Uganda's environmental policy into action at community level. It looks at community-based education and development activities run by VEDCO among smallholder farmers. The study addressed four objectives. For the first objective I developed a conceptual framework through a review of theories informing education in general and environmental education, adult education, community education, and community development in particular. The second objective was to conduct a situational analysis to identify contextual issues related to policy implementation at community level. The third objective was to engage in a participatory action research process with the NGO in the farming community in response to the identified contextual issues, and the fourth was to explore and comment on environmental education methods used within a community context. PRA techniques, interviews, and other participatory data collection methods were used to generate the data. The study reveals contradictions that limit NGO capacity to make appropriate use of participatory education processes in implementing policy-related training at community level. Elements in the National Plan for the Modernisation of Agriculture, for example, conflicted with the principle of sustainable development underlying the policy. VEDCO itself was changing from a social-welfare-oriented organisation into a commercial enterprise pursuing economic goals, which conflicted with its social goals. The capitalist development ideology of the donor was being adopted by VEDCO, which contradicted the goals of people-centred development. This was exacerbated by VEDCO's dependency on donor funds for its activities. Contextual issues like people's history; poverty, gender and inconsistent land policies further complicated the policy implementation processes. There were also inconsistencies in the epistemological assumptions and didactic approaches evident in the implementation. The study shows that the intended emancipatory education processes are more often supplanted by technicist methodologies. Thus, it exposes the underlying historical, ideological and epistemological tensions and contradictions within the field of education, particularly in relation to the `paradigmatic' orientations (neo-classical, liberal and socially critical/emancipatory) outlined in the literature. Conclusions are made at two levels: in relation to the study goals, of examining policy implementation at community level and in terms of the study's contribution to the understanding of current education theory in the context of sustainable development among communities.
- Full Text:
- Date Issued: 2004
Integrated anaerobic/aerobic bioprocess environments and the biodegradation of complex hydrocarbon wastes
- Authors: Ehlers, George A C
- Date: 2004
- Subjects: Hydrocarbons -- Biodegradation Sewage -- Purification -- Anaerobic treatment Water -- Purification -- Biological treatment Anaerobic bacteria Aerobic bacteria
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4011 , http://hdl.handle.net/10962/d1004071
- Description: An investigation of the biodegradation of complex hydrocarbon wastes, with emphasis on chlorinated aromatic compounds, in an anaerobic/aerobic bioprocess environment was made. A reactor configuration was developed consisting of linked anaerobic and aerobic reactors which served as the model for a proposed bioremediation strategy targeting subterranean soil/sediment/aquifer chlorinated phenol-contaminated environments. Here oxygen is frequently limited and sulphate is readily available, as occurs especially in marine sediment and intertidal habitats. In the anaerobic system the successful transformation and mobilization of the model contaminant, 2,4,6-trichlorophenol, was shown to rely on reductive dechlorination by a sulphate-reducing dependent dechlororespiring co-culture. This was followed in the aerobic system by degradation of the pollutant and its metabolites, 2,4-dichlorophenol, 4-chlorophenol and phenol, by immobilized white-rot fungi.The strategy was initially investigated separately in laboratory bench- and intermediate scale reactors whereafter reactors were linked to simulate the integrated biodegradation strategy. The application of the fungal reactor to treat an actual waste stream by degrading complex mixtures of hydrocarbons in a waste oil recycling effluent was also investigated. The mineralization of phenol and 2,4,6-TCP by immobilized fungal cultures was studied in pinewood chip and foam glass bead-packed trickling reactors. The reactors were operated in sequencing batch format. Removal efficiency increased over time and elevated influent phenol and TCP (800 and 85 mg.L⁻¹) concentrations were degraded by > 98 % in 24 – 30 h batch cycles. Comparable performance between the packing materials was shown. Uptake by the packing was negligible and stripping of compounds induced by aeration had a minimal effect on biodegradation efficiency. Reactor performances are discussed in relation to sequencing batch operation and nutrient requirements necessary to sustain fungal activity in inert vs. organic material packed systems. It was shown that a co-culture consisting of sulphate-reducing and dechlororespiring bacteria established in fed-batch and soil flasks, as well as pine chip-packed fluidized bed reactors. Results showed reductive dechlorination of 2,4,6-TCP to be in strict dependence on the activity of the sulphate-reducing population, sulphate and lactate concentrations. Transformation to 2,4-DCP, 4-CP and phenol was enhanced in sulphate deficient conditions. Dechlororespiring activity was found to be dependent on the fermentative activity of sulphate-reducing bacteria, and the culture was also shown to mobilize and dechlorinate TCP in soils contaminated with the pollutant. Linking the systems achieved degradation of the compound by > 99 % through fungal mineralization of metabolites produced in the dechlororespiring stage of the system. pH correction to the anaerobic reactor was found to be necessary since acidic effluent from the fungal reactor inhibited sulphate reduction and dechlorination. The fungal reactor system was evaluated at intermediate-scale using a complex waste oil recycling effluent. Substantial COD reduction (> 96 % in 48 h batch cycles) and removal of specific effluent hydrocarbon components was shown in diluted, undiluted (COD > 37 g.L⁻¹) and 2,4,6-TCP-spiked effluents. Industrial application of the fungal reactor was evaluated in a 14 m³ pilot plant operated on-site at a waste oil processing plant.
- Full Text:
- Date Issued: 2004
- Authors: Ehlers, George A C
- Date: 2004
- Subjects: Hydrocarbons -- Biodegradation Sewage -- Purification -- Anaerobic treatment Water -- Purification -- Biological treatment Anaerobic bacteria Aerobic bacteria
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4011 , http://hdl.handle.net/10962/d1004071
- Description: An investigation of the biodegradation of complex hydrocarbon wastes, with emphasis on chlorinated aromatic compounds, in an anaerobic/aerobic bioprocess environment was made. A reactor configuration was developed consisting of linked anaerobic and aerobic reactors which served as the model for a proposed bioremediation strategy targeting subterranean soil/sediment/aquifer chlorinated phenol-contaminated environments. Here oxygen is frequently limited and sulphate is readily available, as occurs especially in marine sediment and intertidal habitats. In the anaerobic system the successful transformation and mobilization of the model contaminant, 2,4,6-trichlorophenol, was shown to rely on reductive dechlorination by a sulphate-reducing dependent dechlororespiring co-culture. This was followed in the aerobic system by degradation of the pollutant and its metabolites, 2,4-dichlorophenol, 4-chlorophenol and phenol, by immobilized white-rot fungi.The strategy was initially investigated separately in laboratory bench- and intermediate scale reactors whereafter reactors were linked to simulate the integrated biodegradation strategy. The application of the fungal reactor to treat an actual waste stream by degrading complex mixtures of hydrocarbons in a waste oil recycling effluent was also investigated. The mineralization of phenol and 2,4,6-TCP by immobilized fungal cultures was studied in pinewood chip and foam glass bead-packed trickling reactors. The reactors were operated in sequencing batch format. Removal efficiency increased over time and elevated influent phenol and TCP (800 and 85 mg.L⁻¹) concentrations were degraded by > 98 % in 24 – 30 h batch cycles. Comparable performance between the packing materials was shown. Uptake by the packing was negligible and stripping of compounds induced by aeration had a minimal effect on biodegradation efficiency. Reactor performances are discussed in relation to sequencing batch operation and nutrient requirements necessary to sustain fungal activity in inert vs. organic material packed systems. It was shown that a co-culture consisting of sulphate-reducing and dechlororespiring bacteria established in fed-batch and soil flasks, as well as pine chip-packed fluidized bed reactors. Results showed reductive dechlorination of 2,4,6-TCP to be in strict dependence on the activity of the sulphate-reducing population, sulphate and lactate concentrations. Transformation to 2,4-DCP, 4-CP and phenol was enhanced in sulphate deficient conditions. Dechlororespiring activity was found to be dependent on the fermentative activity of sulphate-reducing bacteria, and the culture was also shown to mobilize and dechlorinate TCP in soils contaminated with the pollutant. Linking the systems achieved degradation of the compound by > 99 % through fungal mineralization of metabolites produced in the dechlororespiring stage of the system. pH correction to the anaerobic reactor was found to be necessary since acidic effluent from the fungal reactor inhibited sulphate reduction and dechlorination. The fungal reactor system was evaluated at intermediate-scale using a complex waste oil recycling effluent. Substantial COD reduction (> 96 % in 48 h batch cycles) and removal of specific effluent hydrocarbon components was shown in diluted, undiluted (COD > 37 g.L⁻¹) and 2,4,6-TCP-spiked effluents. Industrial application of the fungal reactor was evaluated in a 14 m³ pilot plant operated on-site at a waste oil processing plant.
- Full Text:
- Date Issued: 2004
Towards the development of species-specific fish production models for small reservoirs in Southern Africa
- Authors: Potts, Warren M
- Date: 2004
- Subjects: Freshwater fishes -- Africa, Southern Fish populations -- Africa, Southern Fisheries -- Africa, Southern Sustainable fisheries -- Africa, Southern Labeo -- Reproduction Cyprinidae -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5330 , http://hdl.handle.net/10962/d1005176
- Description: The fish populations in small southern African reservoirs are largely unexploited and there is potential for fisheries development. However, the development of sustainable fisheries requires reliable estimates of potential yield or production. Empirical models that have been developed to predict fish production only apply to large water bodies and only predict total fish production, not the production of individual species. Small reservoirs generally have few commercially important species and therefore species-specific fish production models are an alternative approach. The small reservoirs of the Eastern Cape are dominated by the moggel (Labeo umbratus). The principal objectives of this thesis were to gain an understanding of the ecology of small reservoirs and the function of moggel in these systems. This information was used to design a research approach to rapidly develop species-specific models for small reservoirs in southern Africa. The limnology of two small reservoirs was compared. During the study period the reservoirs were turbid and showed a warm, monomictic pattern of thermal stratification. Anthropogenic pressure in the reservoir catchments appeared to be the overriding factor increasing the nutrient input to the reservoirs and consequently, influencing the biomass of algae in the reservoirs. The feeding biology of moggel in Katriver and Laing reservoirs was examined. Moggel are detrivorous and successfully digested diatoms. The slower growth rate of moggel in Katriver reservoir was attributed to the poorer nutritional value of the diet as a consequence of the lower concentration of diatoms in the detrital aggregate. The reproductive characteristics of moggel were examined in four reservoirs. Moggel were able to reproduce successfully in the reservoirs. This could be attributed to their r-selected reproductive strategy, with a high fecundity and an extended spawning season and their ability to spawn in a floodplain environment. Differences in recruitment success between years were found to be a consequence of the timing and duration of seasonal rains. The number of mature females in a population and the availability of suitable spawning habitat influenced recruitment success. The life history of the moggel in five reservoirs was compared. Growth appeared to be related to food availability, while mortality was lower in the populations where food was abundant and there were less predatory species. Size and age at maturity were not affected by environmental factors, but were dependent on growth and mortality. Three contrasting methods were used to estimate moggel gillnet selectivity. The Sechin, direct fyke net method and length-structured model all yielded similar results and correction factors obtained from the selectivity study were applied to the gillnet data to estimate the fish population size and structure in each reservoir. Using information from the life history and selectivity studies, the biomass and production of five moggel populations was estimated and related to abiotic and biotic factors in the reservoirs and their catchments. Moggel biomass and production was dependent on the biomass of algae, which was dependent on morphoedaphic characteristics of the reservoirs. Small, shallow reservoirs with a reasonable amount of human habitation in their catchments would sustain the highest algal biomass and provided they had adequate spawning habitat would also have the highest moggel biomass and production. The future research requirements for small reservoir fisheries are outlined and include a three-year program to develop a species-specific production model for any of the dominant species.
- Full Text:
- Date Issued: 2004
- Authors: Potts, Warren M
- Date: 2004
- Subjects: Freshwater fishes -- Africa, Southern Fish populations -- Africa, Southern Fisheries -- Africa, Southern Sustainable fisheries -- Africa, Southern Labeo -- Reproduction Cyprinidae -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5330 , http://hdl.handle.net/10962/d1005176
- Description: The fish populations in small southern African reservoirs are largely unexploited and there is potential for fisheries development. However, the development of sustainable fisheries requires reliable estimates of potential yield or production. Empirical models that have been developed to predict fish production only apply to large water bodies and only predict total fish production, not the production of individual species. Small reservoirs generally have few commercially important species and therefore species-specific fish production models are an alternative approach. The small reservoirs of the Eastern Cape are dominated by the moggel (Labeo umbratus). The principal objectives of this thesis were to gain an understanding of the ecology of small reservoirs and the function of moggel in these systems. This information was used to design a research approach to rapidly develop species-specific models for small reservoirs in southern Africa. The limnology of two small reservoirs was compared. During the study period the reservoirs were turbid and showed a warm, monomictic pattern of thermal stratification. Anthropogenic pressure in the reservoir catchments appeared to be the overriding factor increasing the nutrient input to the reservoirs and consequently, influencing the biomass of algae in the reservoirs. The feeding biology of moggel in Katriver and Laing reservoirs was examined. Moggel are detrivorous and successfully digested diatoms. The slower growth rate of moggel in Katriver reservoir was attributed to the poorer nutritional value of the diet as a consequence of the lower concentration of diatoms in the detrital aggregate. The reproductive characteristics of moggel were examined in four reservoirs. Moggel were able to reproduce successfully in the reservoirs. This could be attributed to their r-selected reproductive strategy, with a high fecundity and an extended spawning season and their ability to spawn in a floodplain environment. Differences in recruitment success between years were found to be a consequence of the timing and duration of seasonal rains. The number of mature females in a population and the availability of suitable spawning habitat influenced recruitment success. The life history of the moggel in five reservoirs was compared. Growth appeared to be related to food availability, while mortality was lower in the populations where food was abundant and there were less predatory species. Size and age at maturity were not affected by environmental factors, but were dependent on growth and mortality. Three contrasting methods were used to estimate moggel gillnet selectivity. The Sechin, direct fyke net method and length-structured model all yielded similar results and correction factors obtained from the selectivity study were applied to the gillnet data to estimate the fish population size and structure in each reservoir. Using information from the life history and selectivity studies, the biomass and production of five moggel populations was estimated and related to abiotic and biotic factors in the reservoirs and their catchments. Moggel biomass and production was dependent on the biomass of algae, which was dependent on morphoedaphic characteristics of the reservoirs. Small, shallow reservoirs with a reasonable amount of human habitation in their catchments would sustain the highest algal biomass and provided they had adequate spawning habitat would also have the highest moggel biomass and production. The future research requirements for small reservoir fisheries are outlined and include a three-year program to develop a species-specific production model for any of the dominant species.
- Full Text:
- Date Issued: 2004
Factors affecting the invasion of Pteronia incana (Blue bush) onto hillslopes in Ngqushwa (formerly Peddie) District, Eastern Cape
- Authors: Kakembo, Vincent
- Date: 2004
- Subjects: Shrubs -- South Africa -- Eastern Cape Slopes (Physical geography) -- South Africa -- Eastern Cape Biological invasions -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4833 , http://hdl.handle.net/10962/d1005508
- Description: The factors that influence the invasion of hillslopes by the shrub Pteronia incana in the communal rangelands of Ngqushwa (formerly Peddie) district were investigated. Mgwalana, one of the catchments in the district where encroachment by the species is widespread, was chosen. The study combined field observations with image analysis based on high resolution infrared imagery. The catchment was flown and high resolution infrared images (1mx1m) were taken using a Kodak DCS420 digital, colour-infrared camera. The images were analysed using Idrisi32 and Kilimanjaro GIS versions. The ability of different vegetation indices to separate P. incana from the other cover types was investigated. Field observations of the degree of P. incana invasion in relation to, inter alia, soil surface conditions, slope angle and visible forms of erosion were made. A Digital Elevation Model (DEM) of 20m spatial resolution was used to derive terrain parameters. The presence and absence of P. incana in relation to slope gradient and aspect were determined. The combined influence of the two terrain parameters and land use on the invasion was also investigated. The Topographic Wetness Index (WI), a component of the TOPMODEL was derived from the DEM and its relationship with the spatial distribution of P. incana was explored. Soil moisture dependencies for P. incana and grass species as well as surrogates for runoff under the shrub and adjacent bare areas were determined in the field. A high level of classification accuracy confirmed the reliability of digital camera imagery for spatial analyses. Distinct spectral separability for the surface vegetation cover types was achieved by means of the Perpendicular Vegetation Index (PVI) as opposed to the ratio based vegetation indices (NDVI, SAVI and MSAVI). The absence/presence of P. incana was noted to be strongly influenced by slope angle and aspect. The probability for P. incana occurrence increased with slope steepness and southerly slope orientation. Abandoned and grazing lands were identified as the main invasion hotspots. Blanket invasion of the former signified the high susceptibility of abandoned land to P. incana invasion. The combined influence of land use, slope gradient and aspect was also noted to have promoted the invasion. This is borne out by the concentration of the invasion on abandoned steep slopes with a southerly orientation. Local topographic variations were identified as having a strong bearing on P. incana spatial distribution. The topographically driven WI confirmed this relationship, such that P. incana was associated with the low WI values of convexities. Differences in the moisture dependencies between P. incana and grass species were demonstrated by the greater rooting depth of the former. During field surveys, soil surface crusting was noted as inherent to P. incana patchiness. The coupling between local topography and soil surface crusting underpins soil moisture variability at hillslope and patch scales respectively. This in turn determines the competition between P. incana and grass species and the eventual replacement of the latter by the former. A close spatial correlation between fully established P. incana and severe forms of soil erosion was observed. Loss of patchiness and expansion of inter-patch bare areas promote runoff connectivity erosion. As most of the runoff becomes run out, hillslopes tend towards dysfunctional systems. Greater soil moisture storage after rainstorms under P. incana tussocks than the adjacent bare areas signifies the shrub’s water harvesting capabilities. The tussocks could thus serve as a starting-pointbuilding- block for the rehabilitation of dysfunctional hillslope systems.
- Full Text:
- Date Issued: 2004
- Authors: Kakembo, Vincent
- Date: 2004
- Subjects: Shrubs -- South Africa -- Eastern Cape Slopes (Physical geography) -- South Africa -- Eastern Cape Biological invasions -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4833 , http://hdl.handle.net/10962/d1005508
- Description: The factors that influence the invasion of hillslopes by the shrub Pteronia incana in the communal rangelands of Ngqushwa (formerly Peddie) district were investigated. Mgwalana, one of the catchments in the district where encroachment by the species is widespread, was chosen. The study combined field observations with image analysis based on high resolution infrared imagery. The catchment was flown and high resolution infrared images (1mx1m) were taken using a Kodak DCS420 digital, colour-infrared camera. The images were analysed using Idrisi32 and Kilimanjaro GIS versions. The ability of different vegetation indices to separate P. incana from the other cover types was investigated. Field observations of the degree of P. incana invasion in relation to, inter alia, soil surface conditions, slope angle and visible forms of erosion were made. A Digital Elevation Model (DEM) of 20m spatial resolution was used to derive terrain parameters. The presence and absence of P. incana in relation to slope gradient and aspect were determined. The combined influence of the two terrain parameters and land use on the invasion was also investigated. The Topographic Wetness Index (WI), a component of the TOPMODEL was derived from the DEM and its relationship with the spatial distribution of P. incana was explored. Soil moisture dependencies for P. incana and grass species as well as surrogates for runoff under the shrub and adjacent bare areas were determined in the field. A high level of classification accuracy confirmed the reliability of digital camera imagery for spatial analyses. Distinct spectral separability for the surface vegetation cover types was achieved by means of the Perpendicular Vegetation Index (PVI) as opposed to the ratio based vegetation indices (NDVI, SAVI and MSAVI). The absence/presence of P. incana was noted to be strongly influenced by slope angle and aspect. The probability for P. incana occurrence increased with slope steepness and southerly slope orientation. Abandoned and grazing lands were identified as the main invasion hotspots. Blanket invasion of the former signified the high susceptibility of abandoned land to P. incana invasion. The combined influence of land use, slope gradient and aspect was also noted to have promoted the invasion. This is borne out by the concentration of the invasion on abandoned steep slopes with a southerly orientation. Local topographic variations were identified as having a strong bearing on P. incana spatial distribution. The topographically driven WI confirmed this relationship, such that P. incana was associated with the low WI values of convexities. Differences in the moisture dependencies between P. incana and grass species were demonstrated by the greater rooting depth of the former. During field surveys, soil surface crusting was noted as inherent to P. incana patchiness. The coupling between local topography and soil surface crusting underpins soil moisture variability at hillslope and patch scales respectively. This in turn determines the competition between P. incana and grass species and the eventual replacement of the latter by the former. A close spatial correlation between fully established P. incana and severe forms of soil erosion was observed. Loss of patchiness and expansion of inter-patch bare areas promote runoff connectivity erosion. As most of the runoff becomes run out, hillslopes tend towards dysfunctional systems. Greater soil moisture storage after rainstorms under P. incana tussocks than the adjacent bare areas signifies the shrub’s water harvesting capabilities. The tussocks could thus serve as a starting-pointbuilding- block for the rehabilitation of dysfunctional hillslope systems.
- Full Text:
- Date Issued: 2004
An exploration of teacher perceptions and actions to conserve wetlands in Kenya
- Authors: Ndaruga, Ayub Macharia
- Date: 2004
- Subjects: Wetlands -- Kenya Wetland conservation -- Kenya Wetland conservation -- Kenya -- Study and teaching ( Elementary) Wetlands -- Kenya -- Study and teaching (Elementary) Environmental education -- Kenya Sustainable development -- Study and teaching (Elementary) -- Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1535 , http://hdl.handle.net/10962/d1003417
- Description: This thesis presents the findings of an exploration of teacher perceptions and actions to conserve wetlands in Kenya. It reports findings of a case study survey done with 54 primary school teachers from seven of eight Kenyan provinces. The teachers were sampled from a larger group of 242 teachers who participated in an in-service course on wetlands conservation. The in-service course engaged teachers in exploring various aspects of wetlands and how they could enhance their conservation using both formal and non-formal contexts. The survey approach was used in the research and was augmented with a reflective process. Survey tools used were the questionnaires and interviews. The reflective process entailed observation, document analysis, field notes and the researcher’s diary. Research data was analysed in several stages. The study revealed that teachers were users of local wetlands just like other members of their communities. The teachers differed among themselves with respect to their perceptions of the value and threats to their local wetlands. The teachers also differed in their perceptions of community awareness of their local wetlands. The teachers’ perceptions about environmental education and wetlands were not holistic. The teachers recorded various opportunities to foster wetlands conservation in their local contexts at school and the community. These were their fellow teachers, the pupils, the subjects taught, clubs, environmental days and the community. The relative importance of these opportunities differed among the teachers. Many teachers claimed being motivated to promote wetlands conservation using both formal and non-formal contexts. Their motivation was based on diverse aspects of wetlands, education and the in-service training they attended in 1999. However, the intensity of motivation differed for each aspect. For instance, at community level in-service training was a major motivator while the curriculum aspects were not mentioned at all. Teachers reported having involved their pupils and the community in several activities to conserve the local wetlands. These activities seemed to be dominated by theoretical approaches, eco-management activities and visits to wetlands. There was little evidence to indicate the teachers being engaged in addressing the implications for sustainability of the perceived local wetland values and threats. The activities reported also failed to show engagement with local environmental problems as a deliberate proactive process involving exploration, discussion, action taking and reflection. Most of the activities were presented as one off activities rather than as a cyclic continuously improving series of interventions. The overall scenario presented by the teachers is one of inadequacy in addressing the sustainable use of wetlands. Teachers suggested various constraints that affect their realisation of environmental education for wetlands sustainability. The constraints traverse various aspects of the economic, biophysical, political, educational and social aspects of wetlands conservation. The study suggested the need for teachers to treat their contextual and personal conceptions as problematic rather than as simplistic or linear issues and to formulate ways to address them. This study suggests a potential but under-utilised opportunity to promote wetlands sustainability. The overall picture generated by the data in this study is a need to consider wetland training for teachers that integrates the holistic aspects of wetlands as well as the environmental education for sustainability perspectives grounded in local contexts.
- Full Text:
- Date Issued: 2004
- Authors: Ndaruga, Ayub Macharia
- Date: 2004
- Subjects: Wetlands -- Kenya Wetland conservation -- Kenya Wetland conservation -- Kenya -- Study and teaching ( Elementary) Wetlands -- Kenya -- Study and teaching (Elementary) Environmental education -- Kenya Sustainable development -- Study and teaching (Elementary) -- Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1535 , http://hdl.handle.net/10962/d1003417
- Description: This thesis presents the findings of an exploration of teacher perceptions and actions to conserve wetlands in Kenya. It reports findings of a case study survey done with 54 primary school teachers from seven of eight Kenyan provinces. The teachers were sampled from a larger group of 242 teachers who participated in an in-service course on wetlands conservation. The in-service course engaged teachers in exploring various aspects of wetlands and how they could enhance their conservation using both formal and non-formal contexts. The survey approach was used in the research and was augmented with a reflective process. Survey tools used were the questionnaires and interviews. The reflective process entailed observation, document analysis, field notes and the researcher’s diary. Research data was analysed in several stages. The study revealed that teachers were users of local wetlands just like other members of their communities. The teachers differed among themselves with respect to their perceptions of the value and threats to their local wetlands. The teachers also differed in their perceptions of community awareness of their local wetlands. The teachers’ perceptions about environmental education and wetlands were not holistic. The teachers recorded various opportunities to foster wetlands conservation in their local contexts at school and the community. These were their fellow teachers, the pupils, the subjects taught, clubs, environmental days and the community. The relative importance of these opportunities differed among the teachers. Many teachers claimed being motivated to promote wetlands conservation using both formal and non-formal contexts. Their motivation was based on diverse aspects of wetlands, education and the in-service training they attended in 1999. However, the intensity of motivation differed for each aspect. For instance, at community level in-service training was a major motivator while the curriculum aspects were not mentioned at all. Teachers reported having involved their pupils and the community in several activities to conserve the local wetlands. These activities seemed to be dominated by theoretical approaches, eco-management activities and visits to wetlands. There was little evidence to indicate the teachers being engaged in addressing the implications for sustainability of the perceived local wetland values and threats. The activities reported also failed to show engagement with local environmental problems as a deliberate proactive process involving exploration, discussion, action taking and reflection. Most of the activities were presented as one off activities rather than as a cyclic continuously improving series of interventions. The overall scenario presented by the teachers is one of inadequacy in addressing the sustainable use of wetlands. Teachers suggested various constraints that affect their realisation of environmental education for wetlands sustainability. The constraints traverse various aspects of the economic, biophysical, political, educational and social aspects of wetlands conservation. The study suggested the need for teachers to treat their contextual and personal conceptions as problematic rather than as simplistic or linear issues and to formulate ways to address them. This study suggests a potential but under-utilised opportunity to promote wetlands sustainability. The overall picture generated by the data in this study is a need to consider wetland training for teachers that integrates the holistic aspects of wetlands as well as the environmental education for sustainability perspectives grounded in local contexts.
- Full Text:
- Date Issued: 2004
A comparative study of egg development in two species of Siphonariid limpets with contrasting developmental modes
- Authors: Pal, Purba
- Date: 2004
- Subjects: Siphonariidae -- Eggs Siphonariidae -- Spawning Limpets
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5826 , http://hdl.handle.net/10962/d1007663
- Description: The family Siphonariidae is considered primitive amongst the basommatophorans although the ancestry and evolutionary relationships of these marine pulmonates are far from settled. This thesis investigates and compares different aspects of egg development and the female reproductive system in two sympatric species of Siphonaria with different developmental mode (S. capensis, a planktonic developer and S. serrata, a direct developer). The study on the seasonality of gametogenesis and spawning shows that they are both spring/summer spawners with continuous sperm production. The egg production is highest in spring and summer with a brief interruption in winter months. The gametogenic cycle when examinated, reveals that both species are simultaneous hermaphrodites once sexually mature. Amongst various factors that are investigated, density of animals has a positive effect on the number of spawn only during peak spawning. Larger individuals of S. capensis and S. serrata contains more mature oocytes in the gonad indicating that the shell length and fecundity of these two limpets are positively correlated. By contrast, parasitism by trematodes has a drastic effect on the reproductive output of these limpets leaving them completely castrated. Egg development in S. capensis and S. serrata shows that both produce yolk auto synthetically (with the help of organelles like RER, Golgi bodies) but S. serrata also incorporates some high molecular weight precursors via endocytotis. The structure as well as the biochemical composition of the egg ribbons is also different between these two species with higher carbohydrate and protein content of collar shaped spawn of S. serrata. S. capensis produces egg ribbons of less fibrous nature containing thinner egg capsules compared to the direct developer. A comparison of both the glandular complex and spermatheca between these two limpets shows no inter specific difference in the structure although the glandular complex of the siphonariids shows fine structural and histochemical similarities with the albumen gland and membrane gland of the opisthobranchs. The structure of the spermatheca suggests that in both species the organ most possibly receives sperm (for degradation only?) and may transport them via the spermathecal duct (for fertilization?). Finally, it is suggested that S. capensis and S. serrata exhibit primitive features (e.g., an autosynthetic mode of vitellogenesis in S. capensis and a single glandular complex composed of an albumen and a mucous gland) compared to other basommatophorans, which should be considered in future phylogenetic investigations.
- Full Text:
- Date Issued: 2004
- Authors: Pal, Purba
- Date: 2004
- Subjects: Siphonariidae -- Eggs Siphonariidae -- Spawning Limpets
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5826 , http://hdl.handle.net/10962/d1007663
- Description: The family Siphonariidae is considered primitive amongst the basommatophorans although the ancestry and evolutionary relationships of these marine pulmonates are far from settled. This thesis investigates and compares different aspects of egg development and the female reproductive system in two sympatric species of Siphonaria with different developmental mode (S. capensis, a planktonic developer and S. serrata, a direct developer). The study on the seasonality of gametogenesis and spawning shows that they are both spring/summer spawners with continuous sperm production. The egg production is highest in spring and summer with a brief interruption in winter months. The gametogenic cycle when examinated, reveals that both species are simultaneous hermaphrodites once sexually mature. Amongst various factors that are investigated, density of animals has a positive effect on the number of spawn only during peak spawning. Larger individuals of S. capensis and S. serrata contains more mature oocytes in the gonad indicating that the shell length and fecundity of these two limpets are positively correlated. By contrast, parasitism by trematodes has a drastic effect on the reproductive output of these limpets leaving them completely castrated. Egg development in S. capensis and S. serrata shows that both produce yolk auto synthetically (with the help of organelles like RER, Golgi bodies) but S. serrata also incorporates some high molecular weight precursors via endocytotis. The structure as well as the biochemical composition of the egg ribbons is also different between these two species with higher carbohydrate and protein content of collar shaped spawn of S. serrata. S. capensis produces egg ribbons of less fibrous nature containing thinner egg capsules compared to the direct developer. A comparison of both the glandular complex and spermatheca between these two limpets shows no inter specific difference in the structure although the glandular complex of the siphonariids shows fine structural and histochemical similarities with the albumen gland and membrane gland of the opisthobranchs. The structure of the spermatheca suggests that in both species the organ most possibly receives sperm (for degradation only?) and may transport them via the spermathecal duct (for fertilization?). Finally, it is suggested that S. capensis and S. serrata exhibit primitive features (e.g., an autosynthetic mode of vitellogenesis in S. capensis and a single glandular complex composed of an albumen and a mucous gland) compared to other basommatophorans, which should be considered in future phylogenetic investigations.
- Full Text:
- Date Issued: 2004
The reproductive biology and artificial breeding of ningu Labeo victorianus (Pisces: Cyprinidae)
- Authors: Rutaisire, Justus
- Date: 2004
- Subjects: Fishes -- Victoria, Lake , Cyprinidae -- Reproduction , Labeo -- Reproduction , Labeo
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5317 , http://hdl.handle.net/10962/d1005162
- Description: Lake Victoria, the largest tropical lake, has faced an unprecedented assault on its ecosystem through a variety of anthropomorphic causes that include the introduction of Nile perch Lates niloticus and over-fishing. As a result there have been species extinctions and declining fish population trends. This thesis explores options for reversing these declining population trends and the restoration of collapsed fisheries based on indigenous non-cichlid species. A candidate species was chosen - the cyprinid fish Labeo victorianus. This thesis studied various aspects of L. victorianus' reproductive biology in two geographically distant populations. These included general reproductive patterns in relation to proximate environmental conditions, gonadal development and recrudescence, sex development, characterisation of genetic and morphological diversity, and induced spawning. Fish from both populations were found to be potamodrometic, and highly fecund, iteroparous spawners. L. victorianus was also shown to be an undifferentiated gonochorist, where all individuals pass through an intersexual juvenile stage prior to differentiation, and maturation to either sex. Sexual maturity was attained at a significantly larger size within the Kagera River than that of Sio River fish – possibly as a response to genotypic and/or phenotypic differences. Spawning seemed to be synchronised with rainfall in Kagera River - a pattern that was not strictly adhered to with the Sio River. Thorough microscopic investigation of recrudescence patterns indicated there was uninterrupted spawning in fish from the Kagera River followed by Type I oocyte atresia. In contrast, there was a 90% spawning failure, as characterised by Type II oocyte atresia, within the Sio River population. Aspects of spermatogenesis and sperm ultrastructure using light- and ultramicrotomic methods are described. Although the populations had varying reproductive biology parameters and were morphologically distinct, they remained undifferentiated at the mitochondrial level. Both populations were characterised by low nucleotide diversity – a feature attributed to a bottleneck event. The option of captive breeding was explored by conducting induced spawning experiments. Success was only achieved with a decapeptide Gonadotropic Releasing Hormone ([D-Arg⁶, Pro⁹-NEt])-sGnRH) in combination with a water-soluble dopamine receptor antagonist metoclopramide. This thesis stresses the importance of a research-oriented approach in the conservation of Lake Victoria's indigenous fish resources. It was concluded that information needed for the development of management policies can be generated within a reasonably short time period, of approximately three years, with modest levels of funding support.
- Full Text:
- Date Issued: 2004
- Authors: Rutaisire, Justus
- Date: 2004
- Subjects: Fishes -- Victoria, Lake , Cyprinidae -- Reproduction , Labeo -- Reproduction , Labeo
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5317 , http://hdl.handle.net/10962/d1005162
- Description: Lake Victoria, the largest tropical lake, has faced an unprecedented assault on its ecosystem through a variety of anthropomorphic causes that include the introduction of Nile perch Lates niloticus and over-fishing. As a result there have been species extinctions and declining fish population trends. This thesis explores options for reversing these declining population trends and the restoration of collapsed fisheries based on indigenous non-cichlid species. A candidate species was chosen - the cyprinid fish Labeo victorianus. This thesis studied various aspects of L. victorianus' reproductive biology in two geographically distant populations. These included general reproductive patterns in relation to proximate environmental conditions, gonadal development and recrudescence, sex development, characterisation of genetic and morphological diversity, and induced spawning. Fish from both populations were found to be potamodrometic, and highly fecund, iteroparous spawners. L. victorianus was also shown to be an undifferentiated gonochorist, where all individuals pass through an intersexual juvenile stage prior to differentiation, and maturation to either sex. Sexual maturity was attained at a significantly larger size within the Kagera River than that of Sio River fish – possibly as a response to genotypic and/or phenotypic differences. Spawning seemed to be synchronised with rainfall in Kagera River - a pattern that was not strictly adhered to with the Sio River. Thorough microscopic investigation of recrudescence patterns indicated there was uninterrupted spawning in fish from the Kagera River followed by Type I oocyte atresia. In contrast, there was a 90% spawning failure, as characterised by Type II oocyte atresia, within the Sio River population. Aspects of spermatogenesis and sperm ultrastructure using light- and ultramicrotomic methods are described. Although the populations had varying reproductive biology parameters and were morphologically distinct, they remained undifferentiated at the mitochondrial level. Both populations were characterised by low nucleotide diversity – a feature attributed to a bottleneck event. The option of captive breeding was explored by conducting induced spawning experiments. Success was only achieved with a decapeptide Gonadotropic Releasing Hormone ([D-Arg⁶, Pro⁹-NEt])-sGnRH) in combination with a water-soluble dopamine receptor antagonist metoclopramide. This thesis stresses the importance of a research-oriented approach in the conservation of Lake Victoria's indigenous fish resources. It was concluded that information needed for the development of management policies can be generated within a reasonably short time period, of approximately three years, with modest levels of funding support.
- Full Text:
- Date Issued: 2004
Journeys of the learning soul: Plato to Descartes
- Authors: Hugo, Wayne
- Date: 2004
- Subjects: Education -- Philosophy Education -- History Education, Ancient Education, Greek
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1884 , http://hdl.handle.net/10962/d1005917
- Description: This thesis aims to build up a picture of what it has meant for us within the western canon to educate a human being through the depths and heights of existence. It uses narrative accounts of educational journeys from ancient, medieval and early modern sources to develop an integral picture of the spectrum of education along with the techniques and fore-structures needed to guide a student through the various stages and encounters. Key metaphors, journeys and relationships - Diotirna's ladder of beauty, Plato's cave, Philo's Abraham and Sarah, Origen's bride and Bridegroom, Plotinus' journey of the alone to the Alone, Augustine's Confessions, the tragic love of Abelard and Heloise, Dante's encounters in the infernal, purgatorial and paradisical realms of human experience, Shakespeare's great playing within the same realm, and Descartes' doubting genius provide a rich ensemble, each resonating with the next, opening out intellectual, affective, volitional, and imaginative paths through the full terrain of human existence. This multidimensional approach points towards a flexible and insightful pedagogics that works with the enormous variety and capacity of human learning rather than heavy-handedly insisting on one path, or, even worse, not recognizing and dealing with specific areas of human living that occur in the upper and lower reaches of our educational endeavours. Phenomenological, Hermeneutic and Integral methods suggested by Heidegger and Wilber amongst others were used to inform the process of research. The results of this thesis are not contained in its reconunendations but in the effects of its reading. It is itself a tool that embodies and encourages the principles of an educational tradition that has existed within the history of western learning, not seeking a return to ancient or medieval ways but to provide a backlight that assists current initiatives working with the full range of human potential.
- Full Text:
- Date Issued: 2004
- Authors: Hugo, Wayne
- Date: 2004
- Subjects: Education -- Philosophy Education -- History Education, Ancient Education, Greek
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1884 , http://hdl.handle.net/10962/d1005917
- Description: This thesis aims to build up a picture of what it has meant for us within the western canon to educate a human being through the depths and heights of existence. It uses narrative accounts of educational journeys from ancient, medieval and early modern sources to develop an integral picture of the spectrum of education along with the techniques and fore-structures needed to guide a student through the various stages and encounters. Key metaphors, journeys and relationships - Diotirna's ladder of beauty, Plato's cave, Philo's Abraham and Sarah, Origen's bride and Bridegroom, Plotinus' journey of the alone to the Alone, Augustine's Confessions, the tragic love of Abelard and Heloise, Dante's encounters in the infernal, purgatorial and paradisical realms of human experience, Shakespeare's great playing within the same realm, and Descartes' doubting genius provide a rich ensemble, each resonating with the next, opening out intellectual, affective, volitional, and imaginative paths through the full terrain of human existence. This multidimensional approach points towards a flexible and insightful pedagogics that works with the enormous variety and capacity of human learning rather than heavy-handedly insisting on one path, or, even worse, not recognizing and dealing with specific areas of human living that occur in the upper and lower reaches of our educational endeavours. Phenomenological, Hermeneutic and Integral methods suggested by Heidegger and Wilber amongst others were used to inform the process of research. The results of this thesis are not contained in its reconunendations but in the effects of its reading. It is itself a tool that embodies and encourages the principles of an educational tradition that has existed within the history of western learning, not seeking a return to ancient or medieval ways but to provide a backlight that assists current initiatives working with the full range of human potential.
- Full Text:
- Date Issued: 2004
A phenological and bioclimatic analysis of honey yield in South Africa
- Authors: Illgner, Peter Mark
- Date: 2004
- Subjects: Bee culture -- South Africa -- Statistics Honeybee -- South Africa Bee culture -- South Africa -- Management Honey plants -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5813 , http://hdl.handle.net/10962/d1007153
- Description: This study has investigated the interaction between honeybees and their forage plants and the impact of selected climatic variables on honey production in South Africa. Twenty-seven scale-hive records from 25 localities have been used as a measure of colony honey reserves. At least 944 plant species are visited by honeybees in South Africa for their nectar and/or pollen, with more than half providing both rewards. The entire honeybee flora encompasses 532 genera and 137 families. The flowering phenologies of the different reward categories of the indigenous forage plants are all significantly and positively correlated at the 0.05 level. Similarly, species offering both rewards are significantly and positively correlated with the flowering phenology of the null flora. The same results were obtained for correlations between the different reward categories of the exotic forage plants in South Africa. Of the 30 species pairs which fulfilled the criteria for selection, 23 occurred in sympatry, 5 in allopatry and 2 in possible parapatry. There is evidence for both competition and facilitation within different indigenous species pairs. The lack of geographical correlation in the intra-annual variation in honey stores and the near absence of any statistically significant (p < 0.05) honey related intra-annual intracolonial correlations may indicate that the former is more important than the latter for the determination of the level of honey reserves within a colony. Only one statistically significant correlation was found between either scale-hive record from the University of Pretoria Experimental Farm and any of the selected climatic variables. A one month lag period and/or possible seasonal effects were detected for each variable, with the exception of the duration of sunshine, in the autocorrelation analyses. A possible 12 month seasonal period was also identified in the single series fourier analyses for a number of variables. Similarly, 12 months was also the most frequently recurring period in the crossspectral results for the one scale-hive record (H42). Any activities which have an impact on the landscape have the potential to affect honeybees and/or their forage plants. Honeybee crop or plant pollination may also enhance yields for commercial farmers and facilitate rural food security.
- Full Text:
- Date Issued: 2004
- Authors: Illgner, Peter Mark
- Date: 2004
- Subjects: Bee culture -- South Africa -- Statistics Honeybee -- South Africa Bee culture -- South Africa -- Management Honey plants -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5813 , http://hdl.handle.net/10962/d1007153
- Description: This study has investigated the interaction between honeybees and their forage plants and the impact of selected climatic variables on honey production in South Africa. Twenty-seven scale-hive records from 25 localities have been used as a measure of colony honey reserves. At least 944 plant species are visited by honeybees in South Africa for their nectar and/or pollen, with more than half providing both rewards. The entire honeybee flora encompasses 532 genera and 137 families. The flowering phenologies of the different reward categories of the indigenous forage plants are all significantly and positively correlated at the 0.05 level. Similarly, species offering both rewards are significantly and positively correlated with the flowering phenology of the null flora. The same results were obtained for correlations between the different reward categories of the exotic forage plants in South Africa. Of the 30 species pairs which fulfilled the criteria for selection, 23 occurred in sympatry, 5 in allopatry and 2 in possible parapatry. There is evidence for both competition and facilitation within different indigenous species pairs. The lack of geographical correlation in the intra-annual variation in honey stores and the near absence of any statistically significant (p < 0.05) honey related intra-annual intracolonial correlations may indicate that the former is more important than the latter for the determination of the level of honey reserves within a colony. Only one statistically significant correlation was found between either scale-hive record from the University of Pretoria Experimental Farm and any of the selected climatic variables. A one month lag period and/or possible seasonal effects were detected for each variable, with the exception of the duration of sunshine, in the autocorrelation analyses. A possible 12 month seasonal period was also identified in the single series fourier analyses for a number of variables. Similarly, 12 months was also the most frequently recurring period in the crossspectral results for the one scale-hive record (H42). Any activities which have an impact on the landscape have the potential to affect honeybees and/or their forage plants. Honeybee crop or plant pollination may also enhance yields for commercial farmers and facilitate rural food security.
- Full Text:
- Date Issued: 2004
Price discovery, price behaviour, and efficiency of selected grain commodities traded on the agricultural products division of the JSE securities exchange
- Authors: Viljoen, Christo
- Date: 2004
- Subjects: Johannesburg Stock Exchange Stock exchanges -- South Africa International economic relations Primary commodities -- South Africa Grain trade -- South Africa Financial futures -- South Africa Price regulation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:952 , http://hdl.handle.net/10962/d1002686
- Description: Agricultural commodity derivatives were first introduced in South Africa in 1996 after the deregulation of the former marketing system. In the context of its proposed functions, namely price discovery and risk management, the question arose as to whether the futures market developed over time to performed its role efficiently. According to the Efficient Markets Hypothesis (EMH) an efficient market is one that accurately incorporates all information available at any point in time. The purpose of the research was to address the issue of price discovery efficiency, firstly, focusing on the weak-form methodology. Secondly, considering the behaviour of futures prices over time, the study addressed the concern of anomalies in daily returns – phenomena contradictory to the EMH by implication. Thirdly, as a means of defining the sources of inefficiency, the role of scheduled public information and its impact on futures prices was examined. Therefore, the primary objective of the research was to investigate and identify the main components of agricultural futures market inefficiency within the unique price formation structure of South African grain markets. The assessment of this problem is important in terms of evaluating the growth and development of the futures market for different grain commodities to date. The Exchange needs to review rules and regulations on a frequent basis in order to ensure proper functioning at all times especially in the case of a relatively new and fast growing market. The study contributed to the knowledge of understanding the price adjustment process and its implications for market efficiency in the context of the three grain markets considered. The weak-form efficiency was tested using a co-integration based model. Analysing daily spot and futures prices of white maize, yellow maize, and wheat, results indicated that all three markets were efficient and unbiased. Non-parametric tests revealed the significant presence of day-of-the-week and turn-of-the-month effects in the futures returns of the three commodities. Further non-parametric analyses suggested a high degree of uncertainty in futures returns around scheduled agricultural and macroeconomic information release dates also contributing significantly to the identified anomalies. It was concluded that (1) the markets’ ability to anticipate the contents of future information to be released, (2) the current skewed size distribution of broking members, (3) the significant role of the R/$ exchange rate in the price formation process of South African grains and, therefore, (4) the relationship to and influence of the broader economy enhanced the return effects (anomalies) creating opportunity for profitable arbitrage. This conclusion was mainly attributed to South Africa’s status as a price-taker in the world grain complex as well as the relatively short existence of the local agricultural futures markets.
- Full Text:
- Date Issued: 2004
- Authors: Viljoen, Christo
- Date: 2004
- Subjects: Johannesburg Stock Exchange Stock exchanges -- South Africa International economic relations Primary commodities -- South Africa Grain trade -- South Africa Financial futures -- South Africa Price regulation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:952 , http://hdl.handle.net/10962/d1002686
- Description: Agricultural commodity derivatives were first introduced in South Africa in 1996 after the deregulation of the former marketing system. In the context of its proposed functions, namely price discovery and risk management, the question arose as to whether the futures market developed over time to performed its role efficiently. According to the Efficient Markets Hypothesis (EMH) an efficient market is one that accurately incorporates all information available at any point in time. The purpose of the research was to address the issue of price discovery efficiency, firstly, focusing on the weak-form methodology. Secondly, considering the behaviour of futures prices over time, the study addressed the concern of anomalies in daily returns – phenomena contradictory to the EMH by implication. Thirdly, as a means of defining the sources of inefficiency, the role of scheduled public information and its impact on futures prices was examined. Therefore, the primary objective of the research was to investigate and identify the main components of agricultural futures market inefficiency within the unique price formation structure of South African grain markets. The assessment of this problem is important in terms of evaluating the growth and development of the futures market for different grain commodities to date. The Exchange needs to review rules and regulations on a frequent basis in order to ensure proper functioning at all times especially in the case of a relatively new and fast growing market. The study contributed to the knowledge of understanding the price adjustment process and its implications for market efficiency in the context of the three grain markets considered. The weak-form efficiency was tested using a co-integration based model. Analysing daily spot and futures prices of white maize, yellow maize, and wheat, results indicated that all three markets were efficient and unbiased. Non-parametric tests revealed the significant presence of day-of-the-week and turn-of-the-month effects in the futures returns of the three commodities. Further non-parametric analyses suggested a high degree of uncertainty in futures returns around scheduled agricultural and macroeconomic information release dates also contributing significantly to the identified anomalies. It was concluded that (1) the markets’ ability to anticipate the contents of future information to be released, (2) the current skewed size distribution of broking members, (3) the significant role of the R/$ exchange rate in the price formation process of South African grains and, therefore, (4) the relationship to and influence of the broader economy enhanced the return effects (anomalies) creating opportunity for profitable arbitrage. This conclusion was mainly attributed to South Africa’s status as a price-taker in the world grain complex as well as the relatively short existence of the local agricultural futures markets.
- Full Text:
- Date Issued: 2004
Spirituality in the fiction of Henry Rider Haggard
- Authors: Senior, John
- Date: 2004
- Subjects: Haggard, H. Rider (Henry Rider), 1856-1925 -- Religion Haggard, H. Rider (Henry Rider), 1856-1925 -- Criticism and interpretation Religion in literature Spirituality in literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2209 , http://hdl.handle.net/10962/d1002252
- Description: Neither an unquestioning support for British imperialism nor a personal pre-Jungian philosophy were the driving forces behind Rider Haggard’s beliefs or his literature. These two concerns were secondary to the author’s fascination with the supernatural, a theme prominent in his era, but less so in our own. A declining faith in European religion provided the dominant focal point in Haggard’s work. Although there are important overtones of imperial concern and indeed points of Jungian significance in the texts, these are generally subservient to an intensive wide-ranging spiritual discourse. The place of Haggard’s work in history and its literary merit are thus misunderstood when his spiritualism is not taken into account. No analysis of the author’s work can be complete without first coming to terms with his spiritual ideas and then with their impact on other topics of significance to both the author and audiences of his day. The spiritual or religious aspect of his writing has been largely ignored because of its subtle nature and its relative unfashionability throughout most of the twentieth century in the critical and intellectual climate of the Western world. However, in the Victorian era, under the materialist impact of Darwin, Marx and industrialization, Europe's Christian God was pushed from centre stage, creating widespread spiritual hunger and anguish. In the resulting religious vacuum Haggard's overtures were of particular significance to his audience. In fact, when considered in terms of his immense contemporary popularity, the pervasive presence of spirituality throughout Haggard's works and in his personal writing gives some indication of the subject's enormous importance not only to the author, but to late Victorian society as a whole. In light of this Victorian significance, the spiritual element rises, by its constant presence and persistent foregrounding, to subvert not only the imperial and the Jungian, but even Haggard's overt adventure text by dealing directly with the underlying metaphysical crisis in Western society.
- Full Text:
- Date Issued: 2004
- Authors: Senior, John
- Date: 2004
- Subjects: Haggard, H. Rider (Henry Rider), 1856-1925 -- Religion Haggard, H. Rider (Henry Rider), 1856-1925 -- Criticism and interpretation Religion in literature Spirituality in literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2209 , http://hdl.handle.net/10962/d1002252
- Description: Neither an unquestioning support for British imperialism nor a personal pre-Jungian philosophy were the driving forces behind Rider Haggard’s beliefs or his literature. These two concerns were secondary to the author’s fascination with the supernatural, a theme prominent in his era, but less so in our own. A declining faith in European religion provided the dominant focal point in Haggard’s work. Although there are important overtones of imperial concern and indeed points of Jungian significance in the texts, these are generally subservient to an intensive wide-ranging spiritual discourse. The place of Haggard’s work in history and its literary merit are thus misunderstood when his spiritualism is not taken into account. No analysis of the author’s work can be complete without first coming to terms with his spiritual ideas and then with their impact on other topics of significance to both the author and audiences of his day. The spiritual or religious aspect of his writing has been largely ignored because of its subtle nature and its relative unfashionability throughout most of the twentieth century in the critical and intellectual climate of the Western world. However, in the Victorian era, under the materialist impact of Darwin, Marx and industrialization, Europe's Christian God was pushed from centre stage, creating widespread spiritual hunger and anguish. In the resulting religious vacuum Haggard's overtures were of particular significance to his audience. In fact, when considered in terms of his immense contemporary popularity, the pervasive presence of spirituality throughout Haggard's works and in his personal writing gives some indication of the subject's enormous importance not only to the author, but to late Victorian society as a whole. In light of this Victorian significance, the spiritual element rises, by its constant presence and persistent foregrounding, to subvert not only the imperial and the Jungian, but even Haggard's overt adventure text by dealing directly with the underlying metaphysical crisis in Western society.
- Full Text:
- Date Issued: 2004
A critical investigation into discourses that construct academic literacy at the Durban Institute of Technology
- Authors: McKenna, Sioux
- Date: 2004
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1317 , http://hdl.handle.net/10962/d1004121
- Description: This thesis examines the construction of academic literacy at the Durban Institute of Technology through a discourse analysis of interviews with educators and learners. Academic literacy comprises the norms and values of higher education as manifested in discipline-specific practices. Students are expected to take on these practices, and the underlying epistemologies, without any overt instruction in, or critique of, these ways of being. Lecturer and student discourses are identified and discussed in terms of their impact on the teaching and learning process. This broad context of educator and student understandings is set against the backdrop of the changing educational policies and structures in post-Apartheid South Africa. The changes in approach to academic development are also traced as a setting for the institutional study. The discourses about the intersection between language and learning were found largely to assume that texts, be they lectures, books, assignments etc, are neutral and autonomous of their contexts. Difficulties some learners experience in accessing or producing the expected meaning of these texts were largely ascribed to their problems with language at a surface level rather than to their lack of shared norms regarding the construction of these texts. The study provides an analysis of how the ‘autonomous’ model is manifested iii and illustrates the limitations on curriculum change imposed by this understanding of how texts are constructed and interpreted. Discourses of motivation presume that students’ difficulties in taking on the literacy practices esteemed by the academy are related to attitude. This discourse assumes that learners have a fairly fixed identity, an assumption that did not bear out in the data. The multiple identities of the learners often presented tensions in the acquisition of discipline-specific academic literacies. The learners were found not to invest strongly in an academically literate identity, or were found to experience conflict between this target identity and the identities they brought with them to the institution. The elevation of academic literacy practices is questioned if the surface features, characteristic of these practices, are valued without a concomitant claim to knowledge production. The rapid emergence of a high skills discourse in Universities of Technology in South Africa is also interrogated, given the current emphasis on training for economic growth over discourses of social redress and transformation.
- Full Text:
- Date Issued: 2004
- Authors: McKenna, Sioux
- Date: 2004
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1317 , http://hdl.handle.net/10962/d1004121
- Description: This thesis examines the construction of academic literacy at the Durban Institute of Technology through a discourse analysis of interviews with educators and learners. Academic literacy comprises the norms and values of higher education as manifested in discipline-specific practices. Students are expected to take on these practices, and the underlying epistemologies, without any overt instruction in, or critique of, these ways of being. Lecturer and student discourses are identified and discussed in terms of their impact on the teaching and learning process. This broad context of educator and student understandings is set against the backdrop of the changing educational policies and structures in post-Apartheid South Africa. The changes in approach to academic development are also traced as a setting for the institutional study. The discourses about the intersection between language and learning were found largely to assume that texts, be they lectures, books, assignments etc, are neutral and autonomous of their contexts. Difficulties some learners experience in accessing or producing the expected meaning of these texts were largely ascribed to their problems with language at a surface level rather than to their lack of shared norms regarding the construction of these texts. The study provides an analysis of how the ‘autonomous’ model is manifested iii and illustrates the limitations on curriculum change imposed by this understanding of how texts are constructed and interpreted. Discourses of motivation presume that students’ difficulties in taking on the literacy practices esteemed by the academy are related to attitude. This discourse assumes that learners have a fairly fixed identity, an assumption that did not bear out in the data. The multiple identities of the learners often presented tensions in the acquisition of discipline-specific academic literacies. The learners were found not to invest strongly in an academically literate identity, or were found to experience conflict between this target identity and the identities they brought with them to the institution. The elevation of academic literacy practices is questioned if the surface features, characteristic of these practices, are valued without a concomitant claim to knowledge production. The rapid emergence of a high skills discourse in Universities of Technology in South Africa is also interrogated, given the current emphasis on training for economic growth over discourses of social redress and transformation.
- Full Text:
- Date Issued: 2004
The geology of the Proterozoic Haveri Au-Cu deposit, Southern Finland
- Strauss, Toby Anthony Lavery
- Authors: Strauss, Toby Anthony Lavery
- Date: 2004
- Subjects: Geology, Stratigraphic -- Precambrian , Geology, Stratigraphic -- Proterozoic , Ore deposits -- Finland , Geology -- Finland
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5081 , http://hdl.handle.net/10962/d1015978
- Description: The Haveri Au-Cu deposit is located in southern Finland about 175 km north of Helsinki. It occurs on the northern edge of the continental island arc-type, volcano-sedimentary Tampere Schist Belt (TSB) within the Palaeoproterozoic Svecofennian Domain (2.0 – 1.75 Ga) of the Fennoscandian Shield. The 1.99 Ga Haveri Formation forms the base of the supracrustal stratigraphy consisting of metavolcanic pillow lavas and breccias passing upwards into intercalated metatuffs and metatuffites. There is a continuous gradation upwards from the predominantly volcaniclastic Haveri Formation into the overlying epiclastic meta-greywackes of the Osara Formation. The Haveri deposit is hosted in this contact zone. This supracrustal sequence has been intruded concordantly by quartz-feldspar porphyries. Approximately 1.89 Ga ago, high crustal heat flow led to the generation and emplacement of voluminous synkinematic, I-type, magnetite-series granitoids of the Central Finland Granitoid Complex (CFGC), resulting in coeval high-T/low-P metamorphism (hornfelsic textures), and D₁ deformation. During the crystallisation and cooling of the granitoids, a magmatic-dominated hydrothermal system caused extensive hydrothermal alteration and Cu-Au mineralisation through the late-D₁ to early-D₂ deformation. Initially, a pre-ore Na-Ca alteration phase caused albitisation of the host rock. This was closely followed by strong Ca-Fe alteration, responsible for widespread amphibolitisation and quartz veining and associated with abundant pyrrhotite, magnetite, chalcopyrite and gold mineralisation. More localised calcic-skarn alteration is also present as zoned garnetpyroxene- epidote skarn assemblages with associated pyrrhotite and minor sphalerite, centred on quartzcalcite± scapolite veinlets. Post-ore alteration includes an evolution to more K-rich alteration (biotitisation). Late D₂-retrograde chlorite began to replace the earlier high-T assemblage. Late emanations (post-D₂ and pre-D₃) from the cooling granitoids, under lower temperatures and oxidising conditions, are represented by carbonate-barite veins and epidote veinlets. Later, narrow dolerite dykes were emplaced followed by a weak D₃ deformation, resulting in shearing and structural reactivation along the carbonate-barite bands. This phase was accompanied by pyrite deposition. Both sulphides and oxides are common at Haveri, with ore types varying from massive sulphide and/or magnetite, to networks of veinlets and disseminations of oxides and/or sulphides. Cataclastites, consisting of deformed, brecciated bands of sulphide, with rounded and angular clasts of quartz vein material and altered host-rock are an economically important ore type. Ore minerals are principally pyrrhotite, magnetite and chalcopyrite with lesser amounts of pyrite, molybdenite and sphalerite. There is a general progression from early magnetite, through pyrrhotite to pyrite indicating increasing sulphidation with time. Gold is typically found as free gold within quartz veins and within intense zones of amphibolitisation. Considerable gold is also found in the cataclastite ore type either as invisible gold within the sulphides and/or as free gold within the breccia fragments. The unaltered amphibolites of the Haveri Formation can be classified as medium-K basalts of the tholeiitic trend. Trace and REE support an interpretation of formation in a back-arc basin setting. The unaltered porphyritic rocks are calc-alkaline dacites, and are interpreted, along with the granitoids as having an arc-type origin. This is consistent with the evolution from an initial back-arc basin, through a period of passive margin and/or fore-arc deposition represented by the Osara Formation greywackes and the basal stratigraphy of the TSB, prior to the onset of arc-related volcanic activity characteristic of the TSB and the Svecofennian proper. Using a combination of petrogenetic grids, mineral compositions (garnet-biotite and hornblendeplagioclase thermometers) and oxygen isotope thermometry, peak metamorphism can be constrained to a maximum of approximately 600 °C and 1.5 kbars pressure. Furthermore, the petrogenetic grids indicate that the REDOX conditions can be constrained at 600°C to log f(O₂) values of approximately - 21.0 to -26.0 and -14.5 to -17.5 for the metasedimentary rocks and mafic metavolcanic rocks respectively, thus indicating the presence of a significant REDOX boundary. Amphibole compositions from the Ca-Fe alteration phase (amphibolitisation) indicate iron enrichment with increasing alteration corresponding to higher temperatures of formation. Oxygen isotope studies combined with limited fluid inclusion studies indicate that the Ca-Fe alteration and associated quartz veins formed at high temperatures (530 – 610°C) from low CO₂, low- to moderately saline (<10 eq. wt% NaCl), magmatic-dominated fluids. Fluid inclusion decrepitation textures in the quartz veins suggest isobaric decompression. This is compatible with formation in high-T/low-P environments such as contact aureoles and island arcs. The calcic-skarn assemblage, combined with phase equilibria and sphalerite geothermometry, are indicative of formation at high temperatures (500 – 600 °C) from fluids with higher CO₂ contents and more saline compositions than those responsible for the Fe-Ca alteration. Limited fluid inclusion studies have identified hypersaline inclusions in secondary inclusion trails within quartz. The presence of calcite and scapolite also support formation from CO₂-rich saline fluids. It is suggested that the calcic-skarn alteration and the amphibolitisation evolved from the same fluids, and that P-T changes led to fluid unmixing resulting in two fluid types responsible for the observed alteration variations. Chlorite geothermometry on retrograde chlorite indicates temperatures of 309 – 368 °C. As chlorite represents the latest hydrothermal event, this can be taken as a lower temperature limit for hydrothermal alteration and mineralisation at Haveri.The gold mineralisation at Haveri is related primarily to the Ca-Fe alteration. Under such P-T-X conditions gold was transported as chloride complexes. Ore was localised by a combination of structural controls (shears and folds) and REDOX reactions along the boundary between the oxidised metavolcanics and the reduced metasediments. In addition, fluid unmixing caused an increase in pH, and thus further augmented the precipitation of Cu and Au. During the late D₂-event, temperatures fell below 400 °C, and fluids may have remobilised Au and Cu as bisulphide complexes into the shearcontrolled cataclastites and massive sulphides. The Haveri deposit has many similarities with ore deposit models that include orogenic lode-gold deposits, certain Au-skarn deposits and Fe-oxide Cu-Au deposits. However, many characteristics of the Haveri deposit, including tectonic setting, host lithologies, alteration types, proximity to I-type granitoids and P-T-X conditions of formation, compare favourably with other Early Proterozoic deposits within the TSB and Fennoscandia, as well as many of the deposits in the Cloncurry district of Australia. Consequently, the Haveri deposit can be seen to represent a high-T, Ca-rich member of the recently recognised Fe-oxide Cu-Au group of deposits.
- Full Text:
- Date Issued: 2004
- Authors: Strauss, Toby Anthony Lavery
- Date: 2004
- Subjects: Geology, Stratigraphic -- Precambrian , Geology, Stratigraphic -- Proterozoic , Ore deposits -- Finland , Geology -- Finland
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5081 , http://hdl.handle.net/10962/d1015978
- Description: The Haveri Au-Cu deposit is located in southern Finland about 175 km north of Helsinki. It occurs on the northern edge of the continental island arc-type, volcano-sedimentary Tampere Schist Belt (TSB) within the Palaeoproterozoic Svecofennian Domain (2.0 – 1.75 Ga) of the Fennoscandian Shield. The 1.99 Ga Haveri Formation forms the base of the supracrustal stratigraphy consisting of metavolcanic pillow lavas and breccias passing upwards into intercalated metatuffs and metatuffites. There is a continuous gradation upwards from the predominantly volcaniclastic Haveri Formation into the overlying epiclastic meta-greywackes of the Osara Formation. The Haveri deposit is hosted in this contact zone. This supracrustal sequence has been intruded concordantly by quartz-feldspar porphyries. Approximately 1.89 Ga ago, high crustal heat flow led to the generation and emplacement of voluminous synkinematic, I-type, magnetite-series granitoids of the Central Finland Granitoid Complex (CFGC), resulting in coeval high-T/low-P metamorphism (hornfelsic textures), and D₁ deformation. During the crystallisation and cooling of the granitoids, a magmatic-dominated hydrothermal system caused extensive hydrothermal alteration and Cu-Au mineralisation through the late-D₁ to early-D₂ deformation. Initially, a pre-ore Na-Ca alteration phase caused albitisation of the host rock. This was closely followed by strong Ca-Fe alteration, responsible for widespread amphibolitisation and quartz veining and associated with abundant pyrrhotite, magnetite, chalcopyrite and gold mineralisation. More localised calcic-skarn alteration is also present as zoned garnetpyroxene- epidote skarn assemblages with associated pyrrhotite and minor sphalerite, centred on quartzcalcite± scapolite veinlets. Post-ore alteration includes an evolution to more K-rich alteration (biotitisation). Late D₂-retrograde chlorite began to replace the earlier high-T assemblage. Late emanations (post-D₂ and pre-D₃) from the cooling granitoids, under lower temperatures and oxidising conditions, are represented by carbonate-barite veins and epidote veinlets. Later, narrow dolerite dykes were emplaced followed by a weak D₃ deformation, resulting in shearing and structural reactivation along the carbonate-barite bands. This phase was accompanied by pyrite deposition. Both sulphides and oxides are common at Haveri, with ore types varying from massive sulphide and/or magnetite, to networks of veinlets and disseminations of oxides and/or sulphides. Cataclastites, consisting of deformed, brecciated bands of sulphide, with rounded and angular clasts of quartz vein material and altered host-rock are an economically important ore type. Ore minerals are principally pyrrhotite, magnetite and chalcopyrite with lesser amounts of pyrite, molybdenite and sphalerite. There is a general progression from early magnetite, through pyrrhotite to pyrite indicating increasing sulphidation with time. Gold is typically found as free gold within quartz veins and within intense zones of amphibolitisation. Considerable gold is also found in the cataclastite ore type either as invisible gold within the sulphides and/or as free gold within the breccia fragments. The unaltered amphibolites of the Haveri Formation can be classified as medium-K basalts of the tholeiitic trend. Trace and REE support an interpretation of formation in a back-arc basin setting. The unaltered porphyritic rocks are calc-alkaline dacites, and are interpreted, along with the granitoids as having an arc-type origin. This is consistent with the evolution from an initial back-arc basin, through a period of passive margin and/or fore-arc deposition represented by the Osara Formation greywackes and the basal stratigraphy of the TSB, prior to the onset of arc-related volcanic activity characteristic of the TSB and the Svecofennian proper. Using a combination of petrogenetic grids, mineral compositions (garnet-biotite and hornblendeplagioclase thermometers) and oxygen isotope thermometry, peak metamorphism can be constrained to a maximum of approximately 600 °C and 1.5 kbars pressure. Furthermore, the petrogenetic grids indicate that the REDOX conditions can be constrained at 600°C to log f(O₂) values of approximately - 21.0 to -26.0 and -14.5 to -17.5 for the metasedimentary rocks and mafic metavolcanic rocks respectively, thus indicating the presence of a significant REDOX boundary. Amphibole compositions from the Ca-Fe alteration phase (amphibolitisation) indicate iron enrichment with increasing alteration corresponding to higher temperatures of formation. Oxygen isotope studies combined with limited fluid inclusion studies indicate that the Ca-Fe alteration and associated quartz veins formed at high temperatures (530 – 610°C) from low CO₂, low- to moderately saline (<10 eq. wt% NaCl), magmatic-dominated fluids. Fluid inclusion decrepitation textures in the quartz veins suggest isobaric decompression. This is compatible with formation in high-T/low-P environments such as contact aureoles and island arcs. The calcic-skarn assemblage, combined with phase equilibria and sphalerite geothermometry, are indicative of formation at high temperatures (500 – 600 °C) from fluids with higher CO₂ contents and more saline compositions than those responsible for the Fe-Ca alteration. Limited fluid inclusion studies have identified hypersaline inclusions in secondary inclusion trails within quartz. The presence of calcite and scapolite also support formation from CO₂-rich saline fluids. It is suggested that the calcic-skarn alteration and the amphibolitisation evolved from the same fluids, and that P-T changes led to fluid unmixing resulting in two fluid types responsible for the observed alteration variations. Chlorite geothermometry on retrograde chlorite indicates temperatures of 309 – 368 °C. As chlorite represents the latest hydrothermal event, this can be taken as a lower temperature limit for hydrothermal alteration and mineralisation at Haveri.The gold mineralisation at Haveri is related primarily to the Ca-Fe alteration. Under such P-T-X conditions gold was transported as chloride complexes. Ore was localised by a combination of structural controls (shears and folds) and REDOX reactions along the boundary between the oxidised metavolcanics and the reduced metasediments. In addition, fluid unmixing caused an increase in pH, and thus further augmented the precipitation of Cu and Au. During the late D₂-event, temperatures fell below 400 °C, and fluids may have remobilised Au and Cu as bisulphide complexes into the shearcontrolled cataclastites and massive sulphides. The Haveri deposit has many similarities with ore deposit models that include orogenic lode-gold deposits, certain Au-skarn deposits and Fe-oxide Cu-Au deposits. However, many characteristics of the Haveri deposit, including tectonic setting, host lithologies, alteration types, proximity to I-type granitoids and P-T-X conditions of formation, compare favourably with other Early Proterozoic deposits within the TSB and Fennoscandia, as well as many of the deposits in the Cloncurry district of Australia. Consequently, the Haveri deposit can be seen to represent a high-T, Ca-rich member of the recently recognised Fe-oxide Cu-Au group of deposits.
- Full Text:
- Date Issued: 2004
Characterisation of the J domain aminoacid residues important for the interaction of DNAJ-like proteins with HSP70 chaperones
- Authors: Hennessy, Fritha
- Date: 2004
- Subjects: Heat shock proteins Protein folding Proteins -- Analysis Proteins -- Structure Molecular chaperones
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3937 , http://hdl.handle.net/10962/d1003996
- Description: The 70 kDa heat shock proteins (Hsp70s) are vital for normal protein folding, as they stabilise the unfolded state of nascent polypeptides, allowing these sufficient time to attain a correct tertiary structure. Hsp70s are aided by the DnaJ-like family of proteins, which interact with Hsp70s in order to enhance the chaperone activity of these proteins. DnaJ-like proteins contain a J domain, a seventy amino acid domain consisting of four α-helices, which is defined by the presence of an invariant tripeptide of histidine, proline and aspartic acid (HPD motif). This motif is key to the interaction between DnaJ-like proteins and Hsp70s. This thesis has focused on determining the presence of other conserved residues in the J domain and their role in mediating the interaction of DnaJ-like proteins with partner Hsp70s. DnaJ-like proteins from Agrobacterium tumefaciens RUOR were isolated and used as a model system. A. tumefaciens DnaJ (Agt DnaJ) was able to replace the lack of E. coli DnaJ in an E. coli null mutant strain, however, additional A. tumefaciens DnaJ-like proteins Agt DjC1/DjlA, Agt DjC2 and Agt DjC5 were unable to complement for the lack of E. coli DnaJ. Replacement of the Agt DnaJ J domain with J domains from these proteins resulted in non-functional chimeric proteins, despite some sequence conservation. The kinetics of the basal specific ATPase activity of Agt DnaK, and its ability to have this activity stimulated by Agt DnaJ and Agt DnaJ-H33Q were also investigated. Stimulation of the ATPase activity by Agt DnaJ ranged between 1.5 to 2 fold, but Agt DnaJ-H33Q was unable to stimulate the basal ATPase activity. Conserved amino acids in the J domain were identified in silico, and these residues were substituted in the J domain of Agt DnaJ. The ability of these derivative proteins to replace E. coli DnaJ was investigated. Alterations in the HPD motif gave rise to proteins unable to complement for lack of E. coli DnaJ, consistent with literature. Agt DnaJ-R26A was unable to replace E. coli DnaJ suggesting that Arg26 could be key to the interaction with partner Hsp70s. Agt DnaJ-D59A was unable to replace E. coli DnaJ; substitutions in Asp59 have not previously been shown to impact on the function of DnaJ. Substituting Arg63 in Agt DnaJ abrogated the levels of complementation. Substitution of several structural residues was also found to disrupt the in vivo function of Agt DnaJ suggesting that the maintenance of the structural integrity of the J domain was important for function. This study has identified a number of residues critical to the structure and function of the J domain of Agt DnaJ, and potentially of general importance as molecular determinants for DnaJ-Hsp70 interaction.
- Full Text:
- Date Issued: 2004
- Authors: Hennessy, Fritha
- Date: 2004
- Subjects: Heat shock proteins Protein folding Proteins -- Analysis Proteins -- Structure Molecular chaperones
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3937 , http://hdl.handle.net/10962/d1003996
- Description: The 70 kDa heat shock proteins (Hsp70s) are vital for normal protein folding, as they stabilise the unfolded state of nascent polypeptides, allowing these sufficient time to attain a correct tertiary structure. Hsp70s are aided by the DnaJ-like family of proteins, which interact with Hsp70s in order to enhance the chaperone activity of these proteins. DnaJ-like proteins contain a J domain, a seventy amino acid domain consisting of four α-helices, which is defined by the presence of an invariant tripeptide of histidine, proline and aspartic acid (HPD motif). This motif is key to the interaction between DnaJ-like proteins and Hsp70s. This thesis has focused on determining the presence of other conserved residues in the J domain and their role in mediating the interaction of DnaJ-like proteins with partner Hsp70s. DnaJ-like proteins from Agrobacterium tumefaciens RUOR were isolated and used as a model system. A. tumefaciens DnaJ (Agt DnaJ) was able to replace the lack of E. coli DnaJ in an E. coli null mutant strain, however, additional A. tumefaciens DnaJ-like proteins Agt DjC1/DjlA, Agt DjC2 and Agt DjC5 were unable to complement for the lack of E. coli DnaJ. Replacement of the Agt DnaJ J domain with J domains from these proteins resulted in non-functional chimeric proteins, despite some sequence conservation. The kinetics of the basal specific ATPase activity of Agt DnaK, and its ability to have this activity stimulated by Agt DnaJ and Agt DnaJ-H33Q were also investigated. Stimulation of the ATPase activity by Agt DnaJ ranged between 1.5 to 2 fold, but Agt DnaJ-H33Q was unable to stimulate the basal ATPase activity. Conserved amino acids in the J domain were identified in silico, and these residues were substituted in the J domain of Agt DnaJ. The ability of these derivative proteins to replace E. coli DnaJ was investigated. Alterations in the HPD motif gave rise to proteins unable to complement for lack of E. coli DnaJ, consistent with literature. Agt DnaJ-R26A was unable to replace E. coli DnaJ suggesting that Arg26 could be key to the interaction with partner Hsp70s. Agt DnaJ-D59A was unable to replace E. coli DnaJ; substitutions in Asp59 have not previously been shown to impact on the function of DnaJ. Substituting Arg63 in Agt DnaJ abrogated the levels of complementation. Substitution of several structural residues was also found to disrupt the in vivo function of Agt DnaJ suggesting that the maintenance of the structural integrity of the J domain was important for function. This study has identified a number of residues critical to the structure and function of the J domain of Agt DnaJ, and potentially of general importance as molecular determinants for DnaJ-Hsp70 interaction.
- Full Text:
- Date Issued: 2004