Nutrient supplementation and secondary metaolites in melanoma cells
- Authors: Stoll, Karin Elisabeth
- Date: 1994
- Subjects: Vitamin C -- Therapeutic use Cancer -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4049 , http://hdl.handle.net/10962/d1004110
- Description: Considerable interest exists with regard to the putative therapeutic role of ascorbic acid in various conditions. A condition which has received much attention is cancer, as it is reported that ascorbic acid may be a prophylactic against cancer development. However, the actual involvement of ascorbic acid, an oxidizing/reducing agent, in the development and progression of tumours is presently a subject of much speculation. This study initially addressed the effect of ascorbic acid supplementation over a nutritional concentration range (0 - 100 μg/ml) on the in vitro growth of non-malignant LLCMK and malignant B16 cells. Ascorbic acid supplementation of these two cell types resulted in an overall decrease in the growth of both types of cells. The actual inhibitory mechanism of ascorbic acid on cell growth was not clear. Further study attempted to define and explain a mechanism responsible for this effect. Ascorbic acid has a role in the maintenance of tissue integrity and host defences, thus providing a rational basis for examining its relationship to cancer. Ascorbic acid is lcnown to be essential for the structural integrity of the intercellular matrix of the cells, the latter being a complex aqueous gel containing, amongst other compounds, fats and prostaglandins. Fats and prostaglandins have diverse effects on. membrane stability, enzyme activity and secondary messengers within cells. Hence, this study investigated the effect of ascorbic acid supplementation on certain enzymes and secondary metabolites within the cells, which had the potential to be involved in the control of cell growth. Throughout this study, emphasis was placed on the Bl6 melanoma cells as ascorbic acid supplementation did not significantly affect levels of secondary metabolites within the non-malignant LLCMK cells. Ascorbic acid supplementation of the B16 cells resulted in significant increases in adenylate cyclase activity and cyclic adenosine monophosphate levels, witb a significant decrease in Bl6 cell growth in that particular experiment. As cyclic adenosine monophosphate has a regulatory role in the cell cycle, this study suggested that the inhibitory effect of ascorbic acid supplementation on cell growth was mediated tbrough a final effect provided by the second messenger, cyclic adenosine monophosphate. However, clarification of tbe mechanism of tbe effect of ascorbic acid on adenylate cyclase activity was required. Hence, a further study investigated prostaglandin E₂ levels, as tbese affect adenylate cyclase activity. Prostaglandin E₂ levels were also found to be inversely related to Bl6 cell growth with ascorbic acid supplementation. It thus appeared tbat adenylate cyclase activity was dependent on prostaglandin E₂ levels in the B16 cells, and further study showed that tbis was indeed the case. Here, higher levels of prostaglandin E₂ supplementation of the Bl6 cells inhibited cell growth significantly and also significantly increased adenylate cyclase activity. Arachidonic acid is the precursor of prostaglandin E₂. In the presence of ascorbic acid supplementation, the percentage arachidonic acid composition of the Bl6 cells was inversely correlated with cell growth. Hence, prostaglandin E₂ levels in ascorbic acid supplemented B16 cells appeared dependent on tbe amount of precursor present. This was confirmed when Bl6 cells were supplemented with arachidonic acid. The latter had an inhibitory effect on Bl6 cell growth and also stimulated prostaglandin E₂ production. The cause of tbe inverse relationship between B16 cell growth and arachidonic acid composition with ascorbic acid supplementation was furtber investigated and found to be dependent on tbe uptake of arachidonic acid and other essential fatty acids from tbe medium. The enzymes phospholipase A₂ delta-5 and delta-6-desaturase, and elongase which could influence arachidonic acid levels were not affected to any extent by ascorbic acid supplementation and therefore did not influence the inverse relationship between B16 cell growth and arachidonic acid. Hence, it can be concluded that the effect of ascorbic acid supplementation on the BI6 cells is mediated, in part at least, by cyclic adenosine monophosphate. However, this is not the result of a direct effect of ascorbic acid supplementation. The initial effect of ascorbic acid supplementation concerns fatty acid - in particular arachidonic acid - uptake from the medium, with subsequent cascade effects On secondary metabolites, ultimately affecting the cellular levels of cyclic adenosine monophosphate.
- Full Text:
- Date Issued: 1994
- Authors: Stoll, Karin Elisabeth
- Date: 1994
- Subjects: Vitamin C -- Therapeutic use Cancer -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4049 , http://hdl.handle.net/10962/d1004110
- Description: Considerable interest exists with regard to the putative therapeutic role of ascorbic acid in various conditions. A condition which has received much attention is cancer, as it is reported that ascorbic acid may be a prophylactic against cancer development. However, the actual involvement of ascorbic acid, an oxidizing/reducing agent, in the development and progression of tumours is presently a subject of much speculation. This study initially addressed the effect of ascorbic acid supplementation over a nutritional concentration range (0 - 100 μg/ml) on the in vitro growth of non-malignant LLCMK and malignant B16 cells. Ascorbic acid supplementation of these two cell types resulted in an overall decrease in the growth of both types of cells. The actual inhibitory mechanism of ascorbic acid on cell growth was not clear. Further study attempted to define and explain a mechanism responsible for this effect. Ascorbic acid has a role in the maintenance of tissue integrity and host defences, thus providing a rational basis for examining its relationship to cancer. Ascorbic acid is lcnown to be essential for the structural integrity of the intercellular matrix of the cells, the latter being a complex aqueous gel containing, amongst other compounds, fats and prostaglandins. Fats and prostaglandins have diverse effects on. membrane stability, enzyme activity and secondary messengers within cells. Hence, this study investigated the effect of ascorbic acid supplementation on certain enzymes and secondary metabolites within the cells, which had the potential to be involved in the control of cell growth. Throughout this study, emphasis was placed on the Bl6 melanoma cells as ascorbic acid supplementation did not significantly affect levels of secondary metabolites within the non-malignant LLCMK cells. Ascorbic acid supplementation of the B16 cells resulted in significant increases in adenylate cyclase activity and cyclic adenosine monophosphate levels, witb a significant decrease in Bl6 cell growth in that particular experiment. As cyclic adenosine monophosphate has a regulatory role in the cell cycle, this study suggested that the inhibitory effect of ascorbic acid supplementation on cell growth was mediated tbrough a final effect provided by the second messenger, cyclic adenosine monophosphate. However, clarification of tbe mechanism of tbe effect of ascorbic acid on adenylate cyclase activity was required. Hence, a further study investigated prostaglandin E₂ levels, as tbese affect adenylate cyclase activity. Prostaglandin E₂ levels were also found to be inversely related to Bl6 cell growth with ascorbic acid supplementation. It thus appeared tbat adenylate cyclase activity was dependent on prostaglandin E₂ levels in the B16 cells, and further study showed that tbis was indeed the case. Here, higher levels of prostaglandin E₂ supplementation of the Bl6 cells inhibited cell growth significantly and also significantly increased adenylate cyclase activity. Arachidonic acid is the precursor of prostaglandin E₂. In the presence of ascorbic acid supplementation, the percentage arachidonic acid composition of the Bl6 cells was inversely correlated with cell growth. Hence, prostaglandin E₂ levels in ascorbic acid supplemented B16 cells appeared dependent on tbe amount of precursor present. This was confirmed when Bl6 cells were supplemented with arachidonic acid. The latter had an inhibitory effect on Bl6 cell growth and also stimulated prostaglandin E₂ production. The cause of tbe inverse relationship between B16 cell growth and arachidonic acid composition with ascorbic acid supplementation was furtber investigated and found to be dependent on tbe uptake of arachidonic acid and other essential fatty acids from tbe medium. The enzymes phospholipase A₂ delta-5 and delta-6-desaturase, and elongase which could influence arachidonic acid levels were not affected to any extent by ascorbic acid supplementation and therefore did not influence the inverse relationship between B16 cell growth and arachidonic acid. Hence, it can be concluded that the effect of ascorbic acid supplementation on the BI6 cells is mediated, in part at least, by cyclic adenosine monophosphate. However, this is not the result of a direct effect of ascorbic acid supplementation. The initial effect of ascorbic acid supplementation concerns fatty acid - in particular arachidonic acid - uptake from the medium, with subsequent cascade effects On secondary metabolites, ultimately affecting the cellular levels of cyclic adenosine monophosphate.
- Full Text:
- Date Issued: 1994
Author, ideology and publisher a symbiotic relationship : Lovedale Missionary Press and early Black writing in South Africa: with specific reference to the critical writings of H.I.E. Dlomo
- Authors: Midgley, Henry Peter
- Date: 1994
- Subjects: Shepherd, Robert H W (Robert Henry Wishart), 1888-1971 Dhlomo, H I E (Herbert I E), 1903-1956 Rhodes University Dissertations African literature Lovedale Institution South African literature -- Black authors -- History and criticism South African literature (English) -- History and criticism Politics and literature -- South Africa -- History -- 20th century Press and politics -- South Africa -- History
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2241 , http://hdl.handle.net/10962/d1002284
- Description: The specific instances of R.H.W. Shepherd and H.I.E. Dhlomo are used in this thesis to investigate some of the many factors that influence the formation of a colonial literature, such as politics, social structures and personal ideals. By isolating the Lovedale Mission Press ~s a "contact zone" - a·place where the cultures of the colonizer and the colonized come into direct contact with each other - it is possible to trace how the interaction between these cultures shaped the writing of a particular African writer, H.I.E. Dhlomo. This is done through an analysis of historical factors that shaped the policy of the Lovedale Mission Press in the twentieth century: the development of liberalism in South Africa, the·role of the missionary in African education, the function ofa liberal magazine such as The South African Outlook and the appointment of an ambitious missionary, R.I.W. Shepherd, to the position of Director of Publications. This necessarily included a study of Shepherd's vision of African literature. On the other hand, this study takes cognisance of the factors that shaped Herbert Dhlomo's vision of literature: the development of African nationalism, the entrenchment of segregation as a politial doctrine, and most importantly, his struggle to have his creative writing published by the Lovedale Press. It is shown how Shepherd's vision of what African literature should entail contrasted with Dhlomo's, and how, as a result, Dhlomo deliberately structured his critical writing as a response to Shepherd's Eurocentric approach to African literature.
- Full Text:
- Date Issued: 1994
- Authors: Midgley, Henry Peter
- Date: 1994
- Subjects: Shepherd, Robert H W (Robert Henry Wishart), 1888-1971 Dhlomo, H I E (Herbert I E), 1903-1956 Rhodes University Dissertations African literature Lovedale Institution South African literature -- Black authors -- History and criticism South African literature (English) -- History and criticism Politics and literature -- South Africa -- History -- 20th century Press and politics -- South Africa -- History
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2241 , http://hdl.handle.net/10962/d1002284
- Description: The specific instances of R.H.W. Shepherd and H.I.E. Dhlomo are used in this thesis to investigate some of the many factors that influence the formation of a colonial literature, such as politics, social structures and personal ideals. By isolating the Lovedale Mission Press ~s a "contact zone" - a·place where the cultures of the colonizer and the colonized come into direct contact with each other - it is possible to trace how the interaction between these cultures shaped the writing of a particular African writer, H.I.E. Dhlomo. This is done through an analysis of historical factors that shaped the policy of the Lovedale Mission Press in the twentieth century: the development of liberalism in South Africa, the·role of the missionary in African education, the function ofa liberal magazine such as The South African Outlook and the appointment of an ambitious missionary, R.I.W. Shepherd, to the position of Director of Publications. This necessarily included a study of Shepherd's vision of African literature. On the other hand, this study takes cognisance of the factors that shaped Herbert Dhlomo's vision of literature: the development of African nationalism, the entrenchment of segregation as a politial doctrine, and most importantly, his struggle to have his creative writing published by the Lovedale Press. It is shown how Shepherd's vision of what African literature should entail contrasted with Dhlomo's, and how, as a result, Dhlomo deliberately structured his critical writing as a response to Shepherd's Eurocentric approach to African literature.
- Full Text:
- Date Issued: 1994
Static analysis of functional languages
- Authors: Mountjoy, Jon-Dean
- Date: 1994 , 2012-10-10
- Subjects: Functional programming languages
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4669 , http://hdl.handle.net/10962/d1006690 , Functional programming languages
- Description: Static analysis is the name given to a number of compile time analysis techniques used to automatically generate information which can lead to improvements in the execution performance of function languages. This thesis provides an introduction to these techniques and their implementation. The abstract interpretation framework is an example of a technique used to extract information from a program by providing the program with an alternate semantics and evaluating this program over a non-standard domain. The elements of this domain represent certain properties of interest. This framework is examined in detail, as well as various extensions and variants of it. The use of binary logical relations and program logics as alternative formulations of the framework , and partial equivalence relations as an extension to it, are also looked at. The projection analysis framework determines how much of a sub-expression can be evaluated by examining the context in which the expression is to be evaluated, and provides an elegant method for finding particular types of information from data structures. This is also examined. The most costly operation in implementing an analysis is the computation of fixed points. Methods developed to make this process more efficient are looked at. This leads to the final chapter which highlights the dependencies and relationships between the different frameworks and their mathematical disciplines. , KMBT_223
- Full Text:
- Date Issued: 1994
- Authors: Mountjoy, Jon-Dean
- Date: 1994 , 2012-10-10
- Subjects: Functional programming languages
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4669 , http://hdl.handle.net/10962/d1006690 , Functional programming languages
- Description: Static analysis is the name given to a number of compile time analysis techniques used to automatically generate information which can lead to improvements in the execution performance of function languages. This thesis provides an introduction to these techniques and their implementation. The abstract interpretation framework is an example of a technique used to extract information from a program by providing the program with an alternate semantics and evaluating this program over a non-standard domain. The elements of this domain represent certain properties of interest. This framework is examined in detail, as well as various extensions and variants of it. The use of binary logical relations and program logics as alternative formulations of the framework , and partial equivalence relations as an extension to it, are also looked at. The projection analysis framework determines how much of a sub-expression can be evaluated by examining the context in which the expression is to be evaluated, and provides an elegant method for finding particular types of information from data structures. This is also examined. The most costly operation in implementing an analysis is the computation of fixed points. Methods developed to make this process more efficient are looked at. This leads to the final chapter which highlights the dependencies and relationships between the different frameworks and their mathematical disciplines. , KMBT_223
- Full Text:
- Date Issued: 1994
Babesia canis : a characterization of five field stocks in Southern Africa
- Authors: Van Heerden, Garth William
- Date: 1994
- Subjects: Babesia canis -- Africa, Southern , Tick-borne diseases -- Africa, Southern , Dogs -- Parasites
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5645 , http://hdl.handle.net/10962/d1005327 , Babesia canis -- Africa, Southern , Tick-borne diseases -- Africa, Southern , Dogs -- Parasites
- Description: This study attempted to characterise 5 field stocks of B. canis, collected from various geographic areas of southern Africa in terms of pathogenicity, immune response, cross resistance and antigenic composition. This was done by means of artificial infection of two to four year old Beagle dogs. Serological tests included indirect fluorescent antibody tests, polyacrylamide gel electrophoresis , Western blotting of B. canis antigen and immune serum transfers. The ZIM1, GHT1 , QTN1 and DBN1 stocks were found to be virulent and the JHB1 stock, which might be a cardiac form of babesiosis, was found to be highly virulent. Immune responses of dogs to primary challenges were poor. A second challenge or relapse was important in the development of a resistant immunity. Heterologous challenges showed that dogs which were immune to the ZIM1, QTN1 and DBN1 stocks were partially immune to the JHB1 stock. The dog that was immune to the GHT1 stock was the only one that was totally resistant to the JHB1 stock. Western blots revealed interstock antigenic variation between the JHB1 and the other four stocks. These differences were, however, not great enough to separate the stocks taxonomically.
- Full Text:
- Date Issued: 1994
- Authors: Van Heerden, Garth William
- Date: 1994
- Subjects: Babesia canis -- Africa, Southern , Tick-borne diseases -- Africa, Southern , Dogs -- Parasites
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5645 , http://hdl.handle.net/10962/d1005327 , Babesia canis -- Africa, Southern , Tick-borne diseases -- Africa, Southern , Dogs -- Parasites
- Description: This study attempted to characterise 5 field stocks of B. canis, collected from various geographic areas of southern Africa in terms of pathogenicity, immune response, cross resistance and antigenic composition. This was done by means of artificial infection of two to four year old Beagle dogs. Serological tests included indirect fluorescent antibody tests, polyacrylamide gel electrophoresis , Western blotting of B. canis antigen and immune serum transfers. The ZIM1, GHT1 , QTN1 and DBN1 stocks were found to be virulent and the JHB1 stock, which might be a cardiac form of babesiosis, was found to be highly virulent. Immune responses of dogs to primary challenges were poor. A second challenge or relapse was important in the development of a resistant immunity. Heterologous challenges showed that dogs which were immune to the ZIM1, QTN1 and DBN1 stocks were partially immune to the JHB1 stock. The dog that was immune to the GHT1 stock was the only one that was totally resistant to the JHB1 stock. Western blots revealed interstock antigenic variation between the JHB1 and the other four stocks. These differences were, however, not great enough to separate the stocks taxonomically.
- Full Text:
- Date Issued: 1994
An investigation into the present state of school guidance in Ciskeian secondary schools in the Keiskammahoek area
- Authors: Lombo, Mzimkhulu Solomon
- Date: 1994
- Subjects: Educational counseling -- Keiskammahoek
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1613 , http://hdl.handle.net/10962/d1003495
- Description: Although school guidance and counselling services were established in Ciskeian Secondary Schools in the early 1980's, little appears to be taking place. One is continually hearing the plea for an improvement in the system, but once again little is happening. Before such improvement can take place, however, it needs to be known what exactly is and isn't taking place. Furthermore, the problems preventing the services from operating successfully need to be clarified. This research aims at describing the state of guidance in a group of five secondary schools in the Keiskammahoek area of the Ciskei, and elucidating the problems experienced by practitioners in the field. An open-ended questionnaire was administered to 98 pupils and 18 guidance teachers, and the five principals of these schools were interviewed. The findings, which are discussed in detail, confirm the suspicions of the researcher that little guidance indeed is taking place. Many reasons for this state of affairs are given. Finally, suggestions are made as to how this unsatisfactory situation may be improved.
- Full Text:
- Date Issued: 1994
- Authors: Lombo, Mzimkhulu Solomon
- Date: 1994
- Subjects: Educational counseling -- Keiskammahoek
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1613 , http://hdl.handle.net/10962/d1003495
- Description: Although school guidance and counselling services were established in Ciskeian Secondary Schools in the early 1980's, little appears to be taking place. One is continually hearing the plea for an improvement in the system, but once again little is happening. Before such improvement can take place, however, it needs to be known what exactly is and isn't taking place. Furthermore, the problems preventing the services from operating successfully need to be clarified. This research aims at describing the state of guidance in a group of five secondary schools in the Keiskammahoek area of the Ciskei, and elucidating the problems experienced by practitioners in the field. An open-ended questionnaire was administered to 98 pupils and 18 guidance teachers, and the five principals of these schools were interviewed. The findings, which are discussed in detail, confirm the suspicions of the researcher that little guidance indeed is taking place. Many reasons for this state of affairs are given. Finally, suggestions are made as to how this unsatisfactory situation may be improved.
- Full Text:
- Date Issued: 1994
Delineation of buried stream channels using geophysical techniques
- Authors: Biedler, Murray W
- Date: 1994
- Subjects: Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4823 , http://hdl.handle.net/10962/d1005498 , Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Description: This study sets out to evaluate the use of geophysical methods for delineating buried stream channels, which can act as zones of preferential flow within a less hydraulically conductive aquifer. This information is important for gaining an understanding of flow dynamics of alluvial systems. The most reliable method of delineating the dimensions of aquifers is by drilling, which is an expensive proposition and is best preceded by a preliminary geophysical study to help define target zones for a drilling program. The study area is located adjacent to the Coerney River in the Sundays River Valley. Geologically it consists of approximately 5 metres of alluvial fines, covering 3 metres of coarse cobbles and boulders, all underlain by alternating siltstone and sandstone beds of indeterminate thickness. Throughout the area the water is very shallow at approximately 2 metres depth and the groundwater tends to be very saline. An air photo study revealed an old oxbow channel that had been covered over by subsequent agricultural land use. The geophysical methods available for the study were portable seismic refraction, electrical resistivity and electromagnetics. Preliminary field tests clearly showed that seismics did not produce valid results. The methods of electrical resistivity and electromagnetics produced good data and were subjected to further assessment. A grid was surveyed over the study area and both geophysical methods were applied at regularly spaced stations. Soil samples were taken over the same survey grid and analyzed for electrical conductivity in a soils laboratory. The results were compared to the geophysical data in an attempt to quantify the relationship between geophysical response and soil salinity. The data from the electromagnetic survey showed areas of low electrical conductivity which was a possible indication of zones of preferential groundwater flow. A transect of boreholes was drilled over selected electrical conductivity lows and successfully intersected the buried stream channel. A comparison of the borehole logs with the layered earth models from the Vertical Electrical Soundings indicated that the electrical resistivity method was not responding to the features of the buried stream channel and the cobblestone layer. This proved the electromagnetic method to be more valuable for this particular study
- Full Text:
- Date Issued: 1994
- Authors: Biedler, Murray W
- Date: 1994
- Subjects: Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4823 , http://hdl.handle.net/10962/d1005498 , Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Description: This study sets out to evaluate the use of geophysical methods for delineating buried stream channels, which can act as zones of preferential flow within a less hydraulically conductive aquifer. This information is important for gaining an understanding of flow dynamics of alluvial systems. The most reliable method of delineating the dimensions of aquifers is by drilling, which is an expensive proposition and is best preceded by a preliminary geophysical study to help define target zones for a drilling program. The study area is located adjacent to the Coerney River in the Sundays River Valley. Geologically it consists of approximately 5 metres of alluvial fines, covering 3 metres of coarse cobbles and boulders, all underlain by alternating siltstone and sandstone beds of indeterminate thickness. Throughout the area the water is very shallow at approximately 2 metres depth and the groundwater tends to be very saline. An air photo study revealed an old oxbow channel that had been covered over by subsequent agricultural land use. The geophysical methods available for the study were portable seismic refraction, electrical resistivity and electromagnetics. Preliminary field tests clearly showed that seismics did not produce valid results. The methods of electrical resistivity and electromagnetics produced good data and were subjected to further assessment. A grid was surveyed over the study area and both geophysical methods were applied at regularly spaced stations. Soil samples were taken over the same survey grid and analyzed for electrical conductivity in a soils laboratory. The results were compared to the geophysical data in an attempt to quantify the relationship between geophysical response and soil salinity. The data from the electromagnetic survey showed areas of low electrical conductivity which was a possible indication of zones of preferential groundwater flow. A transect of boreholes was drilled over selected electrical conductivity lows and successfully intersected the buried stream channel. A comparison of the borehole logs with the layered earth models from the Vertical Electrical Soundings indicated that the electrical resistivity method was not responding to the features of the buried stream channel and the cobblestone layer. This proved the electromagnetic method to be more valuable for this particular study
- Full Text:
- Date Issued: 1994
Synthesis and conformational studies of indolizines
- Authors: George, Rosemary
- Date: 1994
- Subjects: Indole alkaloids -- Research , Organic compounds -- Synthesis , Chemistry, Organic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4367 , http://hdl.handle.net/10962/d1005032 , Indole alkaloids -- Research , Organic compounds -- Synthesis , Chemistry, Organic
- Description: The present investigation has involved a kinetic and mechanistic study of the thermal cyclization of 3-acetoxy-3-(2-pyridyl)-2-methylenepropanoate esters and related compounds to 2-substituted indolizines. Substrates for the kinetic study were prepared via the Baylis-Hillmann reaction of pyridine-2-carboxaldehydes with acrylate esters, acrylonitrile and methyl vinyl ketone. The resulting hydroxy compounds were then acetylated to afford the acetoxy derivatives, thermal cyclization of which gave the corresponding 2-substituted indolizines. The cyclization reactions was followed using 'H NMR spectroscopy and were shown to follow firstorder kinetics. The influence of the various substituents on the observed first-order rate constants has been examined and variable temperature studies have permitted evaluation of activation parameters for the formation of methyl indolizine-2-carboxylate and ethyl indolizine-2-carboxylate. An alternative route to 2-substituted indolizines via halogenated derivatives was explored and several halogenated 2-pyridyl derivatives were synthesised and their thermal cyclization to indolizines was attempted. Novel 5-methylindolizine-2-carboxamides were prepared as part of this investigation and dynamic NMR spectroscopy was used to study internal rotation about the amide N-CO bond in these compounds.
- Full Text:
- Date Issued: 1994
- Authors: George, Rosemary
- Date: 1994
- Subjects: Indole alkaloids -- Research , Organic compounds -- Synthesis , Chemistry, Organic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4367 , http://hdl.handle.net/10962/d1005032 , Indole alkaloids -- Research , Organic compounds -- Synthesis , Chemistry, Organic
- Description: The present investigation has involved a kinetic and mechanistic study of the thermal cyclization of 3-acetoxy-3-(2-pyridyl)-2-methylenepropanoate esters and related compounds to 2-substituted indolizines. Substrates for the kinetic study were prepared via the Baylis-Hillmann reaction of pyridine-2-carboxaldehydes with acrylate esters, acrylonitrile and methyl vinyl ketone. The resulting hydroxy compounds were then acetylated to afford the acetoxy derivatives, thermal cyclization of which gave the corresponding 2-substituted indolizines. The cyclization reactions was followed using 'H NMR spectroscopy and were shown to follow firstorder kinetics. The influence of the various substituents on the observed first-order rate constants has been examined and variable temperature studies have permitted evaluation of activation parameters for the formation of methyl indolizine-2-carboxylate and ethyl indolizine-2-carboxylate. An alternative route to 2-substituted indolizines via halogenated derivatives was explored and several halogenated 2-pyridyl derivatives were synthesised and their thermal cyclization to indolizines was attempted. Novel 5-methylindolizine-2-carboxamides were prepared as part of this investigation and dynamic NMR spectroscopy was used to study internal rotation about the amide N-CO bond in these compounds.
- Full Text:
- Date Issued: 1994
The impact of structural adjustment programmes upon the political economy of Zambia: a critical analysis
- Authors: Makan, Amita
- Date: 1994
- Subjects: Structural adjustment (Economic policy) -- Zambia , Zambia -- Economic conditions -- 1964- , Zambia -- Politics and government -- 1964-1991 , Zambia -- Economic conditions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2800 , http://hdl.handle.net/10962/d1003010 , Structural adjustment (Economic policy) -- Zambia , Zambia -- Economic conditions -- 1964- , Zambia -- Politics and government -- 1964-1991 , Zambia -- Economic conditions
- Description: This study begins with a statistical survey setting out the parameters of Zambia's socio-economic decline in the 1980s. In order to unravel the complex reasons for the crisis, the study develops and employs an historical structural framework which emphasises the interconnectedness of historical, political, economic and social processes . Thereafter, an explanation of Zambia's political and economic development is presented as a background for understanding how and why the IMF came to play an increasingly decisive role in the management of the economic crisis in the 1980s. It is argued that patron-client politics in conjunction with a 'coincidence of interests' between local elite and international capital, entrenched the distorted mono-export dependent economy which, in turn, accelerated the economic decline and debt crisis of the 1980s. After presenting an overview of the Fund's philosophy and objectives, close attention is paid to the impact of SAPs on Zambia, especially in terms of how such policies as subsidy withdrawal, de-regulation and devaluation affected the economy, debt-reduction, health and education. While there is no incontrovertible evidence that adjustment policies caused the crisis, they have been largely ineffective in reversing Zambia's economic decline. In fact, due to the IMF's ahistorical and apolitical approach, any gains have been ephemeral and, in many instances, served to exacerbate the suffering of the population. Finally, Zambia's political structures have proved unable and unwilling to implement IMF reforms consistently and this underlies the central point that SAPs, as a strategy, cannot ensure long-term sustainable development.
- Full Text:
- Date Issued: 1994
- Authors: Makan, Amita
- Date: 1994
- Subjects: Structural adjustment (Economic policy) -- Zambia , Zambia -- Economic conditions -- 1964- , Zambia -- Politics and government -- 1964-1991 , Zambia -- Economic conditions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2800 , http://hdl.handle.net/10962/d1003010 , Structural adjustment (Economic policy) -- Zambia , Zambia -- Economic conditions -- 1964- , Zambia -- Politics and government -- 1964-1991 , Zambia -- Economic conditions
- Description: This study begins with a statistical survey setting out the parameters of Zambia's socio-economic decline in the 1980s. In order to unravel the complex reasons for the crisis, the study develops and employs an historical structural framework which emphasises the interconnectedness of historical, political, economic and social processes . Thereafter, an explanation of Zambia's political and economic development is presented as a background for understanding how and why the IMF came to play an increasingly decisive role in the management of the economic crisis in the 1980s. It is argued that patron-client politics in conjunction with a 'coincidence of interests' between local elite and international capital, entrenched the distorted mono-export dependent economy which, in turn, accelerated the economic decline and debt crisis of the 1980s. After presenting an overview of the Fund's philosophy and objectives, close attention is paid to the impact of SAPs on Zambia, especially in terms of how such policies as subsidy withdrawal, de-regulation and devaluation affected the economy, debt-reduction, health and education. While there is no incontrovertible evidence that adjustment policies caused the crisis, they have been largely ineffective in reversing Zambia's economic decline. In fact, due to the IMF's ahistorical and apolitical approach, any gains have been ephemeral and, in many instances, served to exacerbate the suffering of the population. Finally, Zambia's political structures have proved unable and unwilling to implement IMF reforms consistently and this underlies the central point that SAPs, as a strategy, cannot ensure long-term sustainable development.
- Full Text:
- Date Issued: 1994
Torn between skinship and kinship: the phenomenology of self-mutilation
- Authors: Malcolm, Charles F
- Date: 1994
- Subjects: Self-mutilation Case studies Borderline personality disorder
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3012 , http://hdl.handle.net/10962/d1002521
- Description: The aim of this study was to describe the female elf-mutilator's lived experience of cutting herself. A question which would elicit a description of the experience of this phenomenon was formulated. Five self-mutilators were interviewed. The four psychologically richest narratives were chosen for this study. Using the empirical phenomenological method. the four protocols were analysed in detail. Self-mutilation is conceptualized as a cycle wherein the mutilator experiences a diffuse bodily felt-sense that mounts to an unbearable point. She has an irresistible urge to alleviate the distress. She isolates herself and cuts herself with a sharp blade. Upon seeing the blood appear she is overcome with a deep sense of satisfaction. power, and ecstatic pleasure. The blood is perceived to carry the distressing contents out of the body. Concomitantly the self-mutilator recollects a sense of her feelings and her body as belonging to her. Her previously alienated body is felt to be a site of vitality. She also feels removed from further harm. encased in a cocoon of safety that renders her invulnerable to others. However. the cutting can never totally rid the body of distressing feelings. As a result the cycle of cutting wiII be re-enacted. The cutting cycle is conceptualized as a process whereby the self-mutilator suffers from a traumatization of the psyche such that the psychic container is fractured and rendered painfully porous. The act of cutting rids the psyche of unwanted contents such that a sense of going-on-being is restored. The cutting acts to temporarily shore up the rent fabric of the psychic envelope and thereby consolidate a sense of personal boundary. This is a temporary respite from the fracturing of the psychic container in that, once again confronted with interpersonal existence, the self-mutilator begins to feel vulnerable and defenceless. When it seems as if disintegration is again imminent, a cycle of cutting is reconstituted. The findings emergent from the interviews were dialogued with the literature on psychic containers, particularly that which addresses the role of the skin in the formation and functioning of psychic containers.
- Full Text:
- Date Issued: 1994
- Authors: Malcolm, Charles F
- Date: 1994
- Subjects: Self-mutilation Case studies Borderline personality disorder
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3012 , http://hdl.handle.net/10962/d1002521
- Description: The aim of this study was to describe the female elf-mutilator's lived experience of cutting herself. A question which would elicit a description of the experience of this phenomenon was formulated. Five self-mutilators were interviewed. The four psychologically richest narratives were chosen for this study. Using the empirical phenomenological method. the four protocols were analysed in detail. Self-mutilation is conceptualized as a cycle wherein the mutilator experiences a diffuse bodily felt-sense that mounts to an unbearable point. She has an irresistible urge to alleviate the distress. She isolates herself and cuts herself with a sharp blade. Upon seeing the blood appear she is overcome with a deep sense of satisfaction. power, and ecstatic pleasure. The blood is perceived to carry the distressing contents out of the body. Concomitantly the self-mutilator recollects a sense of her feelings and her body as belonging to her. Her previously alienated body is felt to be a site of vitality. She also feels removed from further harm. encased in a cocoon of safety that renders her invulnerable to others. However. the cutting can never totally rid the body of distressing feelings. As a result the cycle of cutting wiII be re-enacted. The cutting cycle is conceptualized as a process whereby the self-mutilator suffers from a traumatization of the psyche such that the psychic container is fractured and rendered painfully porous. The act of cutting rids the psyche of unwanted contents such that a sense of going-on-being is restored. The cutting acts to temporarily shore up the rent fabric of the psychic envelope and thereby consolidate a sense of personal boundary. This is a temporary respite from the fracturing of the psychic container in that, once again confronted with interpersonal existence, the self-mutilator begins to feel vulnerable and defenceless. When it seems as if disintegration is again imminent, a cycle of cutting is reconstituted. The findings emergent from the interviews were dialogued with the literature on psychic containers, particularly that which addresses the role of the skin in the formation and functioning of psychic containers.
- Full Text:
- Date Issued: 1994
Case studies of tutors' responses to student writing and the way in which students interpret these
- Authors: Paxton, Moragh Isobel Jane
- Date: 1994
- Subjects: Written communication -- Study and teaching -- South Africa Written communication -- South Africa -- Case studies Grading and marking (Students) -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1430 , http://hdl.handle.net/10962/d1003311
- Description: This thesis examines tutor feedback on student essays to ascertain the extent to which these responses assist in teaching the academic and specific disciplinary conventions and to determine what is effective feedback and what is not. The investigation constituted an evaluation of a small sample of essays and the framework for this evaluation was developed from a study of current theories of literacy and language teaching. It was further informed by data gathered from interviews with students and tutors and questionnaires completed by them. This was done in order to establish how students interpret and react to feedback and to demonstrate the level of understanding between tutors and students in this mode of communication. The conclusion was that tutor feedback can provide a valuable method for teaching the discourse of the discipline. However, results of the study revealed that communication often breaks down because tutors and students do not share a common language for talking about academic discourse and because students may not have understood the requirements of the task. In addition, the study found that responses to a small group of essays in the lowest mark category and written by second language students, were very inadequate. As the researcher, I concluded that graduate tutors were not well equipped for the task of dealing with these weaker essays. I have made suggestions for future research in this area and I believe that the data from this case study will provide valuable ideas for training tutors for responding to student essays.
- Full Text:
- Date Issued: 1994
- Authors: Paxton, Moragh Isobel Jane
- Date: 1994
- Subjects: Written communication -- Study and teaching -- South Africa Written communication -- South Africa -- Case studies Grading and marking (Students) -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1430 , http://hdl.handle.net/10962/d1003311
- Description: This thesis examines tutor feedback on student essays to ascertain the extent to which these responses assist in teaching the academic and specific disciplinary conventions and to determine what is effective feedback and what is not. The investigation constituted an evaluation of a small sample of essays and the framework for this evaluation was developed from a study of current theories of literacy and language teaching. It was further informed by data gathered from interviews with students and tutors and questionnaires completed by them. This was done in order to establish how students interpret and react to feedback and to demonstrate the level of understanding between tutors and students in this mode of communication. The conclusion was that tutor feedback can provide a valuable method for teaching the discourse of the discipline. However, results of the study revealed that communication often breaks down because tutors and students do not share a common language for talking about academic discourse and because students may not have understood the requirements of the task. In addition, the study found that responses to a small group of essays in the lowest mark category and written by second language students, were very inadequate. As the researcher, I concluded that graduate tutors were not well equipped for the task of dealing with these weaker essays. I have made suggestions for future research in this area and I believe that the data from this case study will provide valuable ideas for training tutors for responding to student essays.
- Full Text:
- Date Issued: 1994
The porphyry copper system and the precious metal-gold potential
- Authors: Gendall, Ian Richard
- Date: 1994
- Subjects: Copper ores , Porphyry , Gold ores -- Geology , Prospecting
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4992 , http://hdl.handle.net/10962/d1005604 , Copper ores , Porphyry , Gold ores -- Geology , Prospecting
- Description: It has been established that porphyry copper/copper-gold deposits have formed from I Ma to 2 Ga ago. Generally, they are related to the Mesozoic-Cenozoic interval with few reported occurrences from the Palaeozoic or Precambrian. A reason cited is the erosion of these deposits which are often related to convergent plate margins and orogenic belts. Observations of the alteration and mineralisation within and around porphyry copper/copper-gold systems have been included in numerous idealised models. These alteration and mineralisation patterns are dependent on the phases of intrusion, the tectonic setting and rock type, depth of emplacement and relationship to coeval volcanics, physiochemical conditions operative within and surrounding the intrusive and many other mechanical and geochemical conditions. Island arc and cratonic arc/margin deposits are generally considered to be richer in gold than their molybdenum-rich, intra-cratonic counterparts. Metal zonation may occur around these copper/copper-gold deposits, e.g. copper in the core moving out to silver, lead, zinc and gold. This zonation is not always present and gold may occur in the core, intermediate or distal zones. Examples of gold-rich porphyry deposits from British Columbia, Chile and the SW Pacific Island regions suggest gold is closely associated with the potassic-rich zones. Generally these gold-rich zones have greater than 2% magnetite and a high oxygen fugacity is considered to be an important control for gold deposition. High Cl contents within the magma are necessary for gold mobility within the host intrusive centres. Beyond this zone HS₂ becomes an important transporting ligand. Exploration for porphyry copper-gold deposits includes an integrated geological, geophysical and geochemical approach. Petrographic work through to Landsat imagery may be used to determine the chemical conditions of the system, ore association, favourable structural zones and alteration patterns, in order to focus exploration activities.
- Full Text:
- Date Issued: 1994
- Authors: Gendall, Ian Richard
- Date: 1994
- Subjects: Copper ores , Porphyry , Gold ores -- Geology , Prospecting
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4992 , http://hdl.handle.net/10962/d1005604 , Copper ores , Porphyry , Gold ores -- Geology , Prospecting
- Description: It has been established that porphyry copper/copper-gold deposits have formed from I Ma to 2 Ga ago. Generally, they are related to the Mesozoic-Cenozoic interval with few reported occurrences from the Palaeozoic or Precambrian. A reason cited is the erosion of these deposits which are often related to convergent plate margins and orogenic belts. Observations of the alteration and mineralisation within and around porphyry copper/copper-gold systems have been included in numerous idealised models. These alteration and mineralisation patterns are dependent on the phases of intrusion, the tectonic setting and rock type, depth of emplacement and relationship to coeval volcanics, physiochemical conditions operative within and surrounding the intrusive and many other mechanical and geochemical conditions. Island arc and cratonic arc/margin deposits are generally considered to be richer in gold than their molybdenum-rich, intra-cratonic counterparts. Metal zonation may occur around these copper/copper-gold deposits, e.g. copper in the core moving out to silver, lead, zinc and gold. This zonation is not always present and gold may occur in the core, intermediate or distal zones. Examples of gold-rich porphyry deposits from British Columbia, Chile and the SW Pacific Island regions suggest gold is closely associated with the potassic-rich zones. Generally these gold-rich zones have greater than 2% magnetite and a high oxygen fugacity is considered to be an important control for gold deposition. High Cl contents within the magma are necessary for gold mobility within the host intrusive centres. Beyond this zone HS₂ becomes an important transporting ligand. Exploration for porphyry copper-gold deposits includes an integrated geological, geophysical and geochemical approach. Petrographic work through to Landsat imagery may be used to determine the chemical conditions of the system, ore association, favourable structural zones and alteration patterns, in order to focus exploration activities.
- Full Text:
- Date Issued: 1994
The comprehension of figurative language in English literary texts by students for whom English is not a mother tongue
- Authors: Winberg, Christine
- Date: 1994
- Subjects: English language -- Study and teaching -- Foreign speakers , English literature -- Study and teaching (Higher) , Context (Linguistics) , Metaphor , Figures of speech
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2366 , http://hdl.handle.net/10962/d1002649 , English language -- Study and teaching -- Foreign speakers , English literature -- Study and teaching (Higher) , Context (Linguistics) , Metaphor , Figures of speech
- Description: This study applies Sperber and Wilson's relevance theory to the comprehension of figurative language in poetry. Students' understanding of metaphor as a linguistic category and comprehension of metaphorical texts are analysed in terms of the principle of relevance. Patterns of comprehension in English first language (Ll) and English second language (ESL) students' analyses of metaphorical texts are discussed and through an analysis of similarities and differences in these patterns of comprehension an attempt is made to develop a pedagogy around relevance theory. Relevance theory's particular emphasis on the role played by "context" in cognition is seen to have significance for the teaching of literature in South African universities. Relevance theory's account of cognition generates a range of educational principles which could be specifically applied to the teaching of metaphor. An appraisal of the strengths and difficulties students experience in expressing their understanding of metaphor in an academic context is included. This was done to further develop relevance theory into a pedagogical approach which takes into account the academic context in which writing occurs. The investigation of the particular difficulties that English metaphor poses for ESL students entailed acquiring a working knowledge of the ways in which metaphor is taught and assessed in DET schools. The interpretations of students of different linguistic, social and educational backgrounds reveal unifying elements that could be incorporated into a pedagogy based on relevance theory. Such a pedagogy would be appropriate to the multilingual/multicultural/multiracial nature of classes in South African universities and would be a more empowering approach to the teaching of English metaphor.
- Full Text:
- Date Issued: 1994
- Authors: Winberg, Christine
- Date: 1994
- Subjects: English language -- Study and teaching -- Foreign speakers , English literature -- Study and teaching (Higher) , Context (Linguistics) , Metaphor , Figures of speech
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2366 , http://hdl.handle.net/10962/d1002649 , English language -- Study and teaching -- Foreign speakers , English literature -- Study and teaching (Higher) , Context (Linguistics) , Metaphor , Figures of speech
- Description: This study applies Sperber and Wilson's relevance theory to the comprehension of figurative language in poetry. Students' understanding of metaphor as a linguistic category and comprehension of metaphorical texts are analysed in terms of the principle of relevance. Patterns of comprehension in English first language (Ll) and English second language (ESL) students' analyses of metaphorical texts are discussed and through an analysis of similarities and differences in these patterns of comprehension an attempt is made to develop a pedagogy around relevance theory. Relevance theory's particular emphasis on the role played by "context" in cognition is seen to have significance for the teaching of literature in South African universities. Relevance theory's account of cognition generates a range of educational principles which could be specifically applied to the teaching of metaphor. An appraisal of the strengths and difficulties students experience in expressing their understanding of metaphor in an academic context is included. This was done to further develop relevance theory into a pedagogical approach which takes into account the academic context in which writing occurs. The investigation of the particular difficulties that English metaphor poses for ESL students entailed acquiring a working knowledge of the ways in which metaphor is taught and assessed in DET schools. The interpretations of students of different linguistic, social and educational backgrounds reveal unifying elements that could be incorporated into a pedagogy based on relevance theory. Such a pedagogy would be appropriate to the multilingual/multicultural/multiracial nature of classes in South African universities and would be a more empowering approach to the teaching of English metaphor.
- Full Text:
- Date Issued: 1994
A classroom-based investigation into the potential of a computer-mediated criterion-referenced test as an evaluation instrument for the assessment of primary end user spreadsheet skills
- Authors: Benn, Kenneth Robert Andrew
- Date: 1994
- Subjects: Education -- Data processing Electronic spreadsheets Criterion-referenced tests Educational tests and measurements
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1447 , http://hdl.handle.net/10962/d1003328
- Description: The demand for innovative end users of information technology is increasing along with the proliferation of computer equipment within the workplace. This has resulted in increasing demands being made upon educational institutions responsible for the education of computer end users. The demands placed upon the teachers are particularly high. Large class groups and limited physical resources make the task especially difficult. One of the most time consuming, yet important, tasks is that of student evaluation. To effectively assess the practical work of information technology students requires intensive study of the storage media upon which the students'efforts have been saved. The purpose of this study was to assess the suitability of criterion-referenced testing techniques applied to the evaluation of end user computing students. Objective questions were administered to the students using Question Mark, a computer-managed test delivery system which enabled quick and efficient management of scoring and data manipulation for empirical analysis. The study was limited to the classroom situation and the assessment of primary spreadsheet skills. In order to operate within these boundaries, empirical techniques were used which enabled the timeous analysis of the students' test results. The findings of this study proved to be encouraging. Computer-mediated criterion-referenced testing techniques were found to be sufficiently reliable for classroom practice when used to assess primary spreadsheet skills. The validation of the assessment technique proved to be problematic because of the constraints imposed by normal classroom practice as well as the lack of an established methodology for evaluating spreadsheet skills. However, sufficient evidence was obtained to warrant further research aimed at assessing the use of computer-mediated criterion-referenced tests to evaluate information technology end user learning in situations beyond the boundaries of the classroom, such as a national certification examination.
- Full Text:
- Date Issued: 1994
- Authors: Benn, Kenneth Robert Andrew
- Date: 1994
- Subjects: Education -- Data processing Electronic spreadsheets Criterion-referenced tests Educational tests and measurements
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1447 , http://hdl.handle.net/10962/d1003328
- Description: The demand for innovative end users of information technology is increasing along with the proliferation of computer equipment within the workplace. This has resulted in increasing demands being made upon educational institutions responsible for the education of computer end users. The demands placed upon the teachers are particularly high. Large class groups and limited physical resources make the task especially difficult. One of the most time consuming, yet important, tasks is that of student evaluation. To effectively assess the practical work of information technology students requires intensive study of the storage media upon which the students'efforts have been saved. The purpose of this study was to assess the suitability of criterion-referenced testing techniques applied to the evaluation of end user computing students. Objective questions were administered to the students using Question Mark, a computer-managed test delivery system which enabled quick and efficient management of scoring and data manipulation for empirical analysis. The study was limited to the classroom situation and the assessment of primary spreadsheet skills. In order to operate within these boundaries, empirical techniques were used which enabled the timeous analysis of the students' test results. The findings of this study proved to be encouraging. Computer-mediated criterion-referenced testing techniques were found to be sufficiently reliable for classroom practice when used to assess primary spreadsheet skills. The validation of the assessment technique proved to be problematic because of the constraints imposed by normal classroom practice as well as the lack of an established methodology for evaluating spreadsheet skills. However, sufficient evidence was obtained to warrant further research aimed at assessing the use of computer-mediated criterion-referenced tests to evaluate information technology end user learning in situations beyond the boundaries of the classroom, such as a national certification examination.
- Full Text:
- Date Issued: 1994
Studies on the bioactivities of selected Eastern Cape seaweeds
- Authors: Carter, Anne Margaret
- Date: 1994
- Subjects: Marine algae -- South Africa -- Eastern Cape , Marine algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4033 , http://hdl.handle.net/10962/d1004093 , Marine algae -- South Africa -- Eastern Cape , Marine algae
- Description: In studies on the bioactivities of selected eastern Cape seaweeds, a suitable extraction solvent, namely methanol was used. The antimicrobial, antineoplastic and antiviral activities were investigated, and a seasonal comparison of antimicrobial activities as well as a scanning electron microscopic study were included. A number of algae were found to display significantly high antibacterial activities, of these, the two red algae Plocamium corallorhiza and Laurencia glomerata and the two brown algae Zonaria subarticulata and Ecklonia biruncinata showed the most potent broad spectrum antibacterial activity. L.glomerata and E.biruncinata were active against all five test bacteria, but were inactive against the yeast Candida albicans. C.albicans was the most resistant organism tested,~with only Peyssonelia capensis, f-corallorhiza and Ulva rigida inhibiting its growth. Of the 17 seaweeds tested, none showed any clear seasonal changes in antimicrobial activity. The microorganisms however did vary in their susceptibility to treatment. Staphylococcus aureus and the Micrococcus species were the most susceptible to treatment by the algal extracts, with the Gram positive endospore former, Bacillus subtilis and the two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa showing more resistance to treatment. C.albicans however was the most resistant organism. In the antineoplastic studies, the brown algae Z.subarticulata, E.biruncinata and Sargassum heterophyllum showed potent activity against both the normal, LLCMK, and cancerous, mouse melanoma-3S0 cells, reducing cell growth in each case. The green algae showed potent activity against the cancerous cells, lowering growth to 30% that of the normal cells. Normal cell growth was unaffected or was stimulated by the presence of these algal extracts. The red algae showed no antineoplastic activity. Representatives of each of the red, brown and green algae were used in the brine shrimp (Artemia salina) cytotoxicity study. None of the algae showed any toxicity towards the brine shrimp. In the antiviral studies against Polio Type 1, strain L-Sa, a reduction in virus infectivity was used as an indication of the presence of antiviral properties in the seaweeds tested. This was done by comparing the virus titres of algal-treated cells with those of untreated cells. Six of the algae tested displayed antiviral activity, these were the two Rhodophyceae Hypnea spicifera and L.glomerata, the two Phaeophyceae Dictyopteris macrocarpa and Dictyota naevosa, and the two Chlorophyceae U.rigida and Halimeda cuneata. Of these, D.naevosa showed particularly strong activity, recording a log reduction in virus titre of 4.
- Full Text:
- Date Issued: 1994
- Authors: Carter, Anne Margaret
- Date: 1994
- Subjects: Marine algae -- South Africa -- Eastern Cape , Marine algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4033 , http://hdl.handle.net/10962/d1004093 , Marine algae -- South Africa -- Eastern Cape , Marine algae
- Description: In studies on the bioactivities of selected eastern Cape seaweeds, a suitable extraction solvent, namely methanol was used. The antimicrobial, antineoplastic and antiviral activities were investigated, and a seasonal comparison of antimicrobial activities as well as a scanning electron microscopic study were included. A number of algae were found to display significantly high antibacterial activities, of these, the two red algae Plocamium corallorhiza and Laurencia glomerata and the two brown algae Zonaria subarticulata and Ecklonia biruncinata showed the most potent broad spectrum antibacterial activity. L.glomerata and E.biruncinata were active against all five test bacteria, but were inactive against the yeast Candida albicans. C.albicans was the most resistant organism tested,~with only Peyssonelia capensis, f-corallorhiza and Ulva rigida inhibiting its growth. Of the 17 seaweeds tested, none showed any clear seasonal changes in antimicrobial activity. The microorganisms however did vary in their susceptibility to treatment. Staphylococcus aureus and the Micrococcus species were the most susceptible to treatment by the algal extracts, with the Gram positive endospore former, Bacillus subtilis and the two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa showing more resistance to treatment. C.albicans however was the most resistant organism. In the antineoplastic studies, the brown algae Z.subarticulata, E.biruncinata and Sargassum heterophyllum showed potent activity against both the normal, LLCMK, and cancerous, mouse melanoma-3S0 cells, reducing cell growth in each case. The green algae showed potent activity against the cancerous cells, lowering growth to 30% that of the normal cells. Normal cell growth was unaffected or was stimulated by the presence of these algal extracts. The red algae showed no antineoplastic activity. Representatives of each of the red, brown and green algae were used in the brine shrimp (Artemia salina) cytotoxicity study. None of the algae showed any toxicity towards the brine shrimp. In the antiviral studies against Polio Type 1, strain L-Sa, a reduction in virus infectivity was used as an indication of the presence of antiviral properties in the seaweeds tested. This was done by comparing the virus titres of algal-treated cells with those of untreated cells. Six of the algae tested displayed antiviral activity, these were the two Rhodophyceae Hypnea spicifera and L.glomerata, the two Phaeophyceae Dictyopteris macrocarpa and Dictyota naevosa, and the two Chlorophyceae U.rigida and Halimeda cuneata. Of these, D.naevosa showed particularly strong activity, recording a log reduction in virus titre of 4.
- Full Text:
- Date Issued: 1994
An investigation of the effects which using the word processor has on the writing of standard six pupils
- Authors: McKenzie, Donald John
- Date: 1994
- Subjects: Written communication -- Study and teaching -- Data processing Word processors in education Language arts -- Computer-assisted instruction English language -- Writing--Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1648 , http://hdl.handle.net/10962/d1003531
- Description: In order to discover to what extent the use of the word processor affects the motivation of high school students when engaged in writing tasks, and to determine the effects of the word processing on the length and quality of their work and editing, two groups, carefully matched in terms of prior computer experience, intelligence and language ability were given eight writing tasks. The test group used word processors while the control group used pen and paper. Their behaviour was closely observed and their writing was subsequently compared. It was found that while the test group were more motivated and spent longer both writing and editing their work, the quality of the work of both groups was similar. The degree of editing was greater for the test group. The conclusion is that there is a place for the use of the word processor in the English classroom, but specific strategies need to be developed to optimise its benefits.
- Full Text:
- Date Issued: 1994
- Authors: McKenzie, Donald John
- Date: 1994
- Subjects: Written communication -- Study and teaching -- Data processing Word processors in education Language arts -- Computer-assisted instruction English language -- Writing--Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1648 , http://hdl.handle.net/10962/d1003531
- Description: In order to discover to what extent the use of the word processor affects the motivation of high school students when engaged in writing tasks, and to determine the effects of the word processing on the length and quality of their work and editing, two groups, carefully matched in terms of prior computer experience, intelligence and language ability were given eight writing tasks. The test group used word processors while the control group used pen and paper. Their behaviour was closely observed and their writing was subsequently compared. It was found that while the test group were more motivated and spent longer both writing and editing their work, the quality of the work of both groups was similar. The degree of editing was greater for the test group. The conclusion is that there is a place for the use of the word processor in the English classroom, but specific strategies need to be developed to optimise its benefits.
- Full Text:
- Date Issued: 1994
South Africa's post-apartheid foreign policy : towards a diplomacy of trade
- Authors: Dullabh, Nitesh Amratlal
- Date: 1994
- Subjects: Foreign trade regulation -- South Africa , South Africa -- Foreign relations
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2774 , http://hdl.handle.net/10962/d1002984 , Foreign trade regulation -- South Africa , South Africa -- Foreign relations
- Description: This thesis attempts to argue that a post-apartheid foreign policy will no longer be based on seeking legitimacy for the South African Government. Instead, it argues that if South Africa wants to grow, both domestically and nternationally, it will be imperative for it (South Africa) to move from an import substitution trade policy to an export-oriented trade policy. It is further suggested that the export-led strategy will be an important component for the promotion of South African international trade in the post-Cold War era. South Africa cannot improve the status of its trade regime by its own doing. It will require the support and assistance of international organizations and hence, the international community. Following the principles, rules and procedures of the General Agreement on Tariffs and Trade (GATT); it is argued, will help South Africa reconstruct its trade policies on the basis that they are free, fair and above all competitive. Furthermore, maintaining a constantly favourable relationship with the international community will allow easy access to international markets for South African goods and services, and eventually the smooth integration of the South African economy in the international political economy. This study, noting the importance of trade with a dedicated commitment to exports, concludes that although exports would flourish, there will be an immediate need for diplomats to be conversant with contemporary international trade developments. This would require diplomats to be innovative, steadfast and disciplined in their day-to-day negotiations. In the final instance, the role of trade in South Africa's future will ultimately be determined by its trade postures and the type of diplomacy to be used by its diplomats.
- Full Text:
- Date Issued: 1994
- Authors: Dullabh, Nitesh Amratlal
- Date: 1994
- Subjects: Foreign trade regulation -- South Africa , South Africa -- Foreign relations
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2774 , http://hdl.handle.net/10962/d1002984 , Foreign trade regulation -- South Africa , South Africa -- Foreign relations
- Description: This thesis attempts to argue that a post-apartheid foreign policy will no longer be based on seeking legitimacy for the South African Government. Instead, it argues that if South Africa wants to grow, both domestically and nternationally, it will be imperative for it (South Africa) to move from an import substitution trade policy to an export-oriented trade policy. It is further suggested that the export-led strategy will be an important component for the promotion of South African international trade in the post-Cold War era. South Africa cannot improve the status of its trade regime by its own doing. It will require the support and assistance of international organizations and hence, the international community. Following the principles, rules and procedures of the General Agreement on Tariffs and Trade (GATT); it is argued, will help South Africa reconstruct its trade policies on the basis that they are free, fair and above all competitive. Furthermore, maintaining a constantly favourable relationship with the international community will allow easy access to international markets for South African goods and services, and eventually the smooth integration of the South African economy in the international political economy. This study, noting the importance of trade with a dedicated commitment to exports, concludes that although exports would flourish, there will be an immediate need for diplomats to be conversant with contemporary international trade developments. This would require diplomats to be innovative, steadfast and disciplined in their day-to-day negotiations. In the final instance, the role of trade in South Africa's future will ultimately be determined by its trade postures and the type of diplomacy to be used by its diplomats.
- Full Text:
- Date Issued: 1994
Methods for assessing the susceptibility of freshwater ecosystems in Southern Africa to invasion by alien aquatic animals
- Authors: De Moor, Irene J
- Date: 1994
- Subjects: Biotic communities -- South Africa , Animal introduction , Freshwater ecology -- Africa, Southern , Animal introduction -- South Africa , Geographic information systems
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5300 , http://hdl.handle.net/10962/d1005145
- Description: Two methods for predicting regions susceptible to invasion by alien aquatic animals were developed for southern Africa (excluding Zimbabwe and Mozambique). In the "traditional" (data-poor) approach, distributions of three categories of alien "indicator" species (warm mesothermal, cold stenothermal and eurytopic) were compared to seven existing biogeographical models of distribution patterns of various animals in southern Africa. On the basis of these comparisons a synthesis model was developed which divided southern Africa into seven regions characterised by their susceptibility to invasion by alien aquatic animals with particular habitat requirements. In the "data-rich," geographic information systems (GIS) approach, the distribution of trout (Oncorhynchus mykiss and Salmo trutta) in selected "sampled regions" was related to elevation (as a surrogate of water temperature) and median annual rainfall (MAR) (as a surrogate of water availability). Using concentration analysis, optimum conditions for trout were identified. Regions within a larger "predictive area" which satisfied these conditions, were plotted as a digital map using the IDRISI package. Using this method seven models of potential trout distribution were generated for the following regions: northern Natal (two); southern Natal/Lesotho/Transkei (three), eastern Cape (two) and western Cape (two). Since two of the models were used to refine the methods, only five models were considered for the final assessment. In a modification of the GIS method, another model of potential trout distribution, based on mean monthly July minimum air temperature and MAR parameters, was developed for the region bounded by 29º - 34º S and 26 º - 32°E. This model showed marked similarities to another model, developed for the region bounded by 29 º - 32°S and 26º - 32°E, which was based on elevation and MAR parameters. The validity of the models developed was assessed by independent experts. Of the six models considered, four received favourable judgements, one was equivocal and one was judged to be poor. Based on these assessments it was concluded that the GIS method has credibility and could be used to develop a "data-rich" model of the susceptibility of southern Africa to invasion by alien aquatic animals. This method represents an alternative to the bioclimatic matching approach developed by scientists in Australia. The GIS method has a number of advantages over the "traditional" method: it is more amenable to testing, has greater flexibility, stores more information, produces images of a finer resolution, and can be easily updated. The traditional method has the advantage of being less expensive and requiring a less extensive database.
- Full Text:
- Date Issued: 1994
- Authors: De Moor, Irene J
- Date: 1994
- Subjects: Biotic communities -- South Africa , Animal introduction , Freshwater ecology -- Africa, Southern , Animal introduction -- South Africa , Geographic information systems
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5300 , http://hdl.handle.net/10962/d1005145
- Description: Two methods for predicting regions susceptible to invasion by alien aquatic animals were developed for southern Africa (excluding Zimbabwe and Mozambique). In the "traditional" (data-poor) approach, distributions of three categories of alien "indicator" species (warm mesothermal, cold stenothermal and eurytopic) were compared to seven existing biogeographical models of distribution patterns of various animals in southern Africa. On the basis of these comparisons a synthesis model was developed which divided southern Africa into seven regions characterised by their susceptibility to invasion by alien aquatic animals with particular habitat requirements. In the "data-rich," geographic information systems (GIS) approach, the distribution of trout (Oncorhynchus mykiss and Salmo trutta) in selected "sampled regions" was related to elevation (as a surrogate of water temperature) and median annual rainfall (MAR) (as a surrogate of water availability). Using concentration analysis, optimum conditions for trout were identified. Regions within a larger "predictive area" which satisfied these conditions, were plotted as a digital map using the IDRISI package. Using this method seven models of potential trout distribution were generated for the following regions: northern Natal (two); southern Natal/Lesotho/Transkei (three), eastern Cape (two) and western Cape (two). Since two of the models were used to refine the methods, only five models were considered for the final assessment. In a modification of the GIS method, another model of potential trout distribution, based on mean monthly July minimum air temperature and MAR parameters, was developed for the region bounded by 29º - 34º S and 26 º - 32°E. This model showed marked similarities to another model, developed for the region bounded by 29 º - 32°S and 26º - 32°E, which was based on elevation and MAR parameters. The validity of the models developed was assessed by independent experts. Of the six models considered, four received favourable judgements, one was equivocal and one was judged to be poor. Based on these assessments it was concluded that the GIS method has credibility and could be used to develop a "data-rich" model of the susceptibility of southern Africa to invasion by alien aquatic animals. This method represents an alternative to the bioclimatic matching approach developed by scientists in Australia. The GIS method has a number of advantages over the "traditional" method: it is more amenable to testing, has greater flexibility, stores more information, produces images of a finer resolution, and can be easily updated. The traditional method has the advantage of being less expensive and requiring a less extensive database.
- Full Text:
- Date Issued: 1994
Perceptions of language teaching in science from student and teacher discourse
- Authors: Garraway, James Windsor
- Date: 1994
- Subjects: Physics -- Study and teaching -- South Africa Language arts -- South Africa Written communication -- Study and teaching -- South Africa Language arts -- Correlation with content subjects -- South Africa Physics teachers -- Language
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1693 , http://hdl.handle.net/10962/d1003576
- Description: The research was concerned with perceptions of language and physics in three strata of participants in a writing across the curriculum teaching course at an intermediate college. The participants were: a language teacher, two physics teachers and a class of twenty physics students - the students were studying in order to enter the Engineering Faculty at the University of Cape Town. The predominant understanding of the teachers was that of a limited interpenetration between the discourse of physics and language teaching. Physics teachers thought that language teachers would experience difficulties with both the concepts and language of physics. In actual practice however, students and the language teacher managed physics knowledge with some degree of success in the language classroom. Some students understood writing as helping them to understand physics. However, the dominant understanding of language was that of knowing the appropriate language of physics for their teachers. An appropriate language understanding was seen as potentially problematic in that it could encourage an unquestioning or monodimensional approach to physics knowledge. As a way around this problem, it was suggested that language teachers teach students to recognise and to use particular genres within science, and to develop their voice within these constraints.
- Full Text:
- Date Issued: 1994
- Authors: Garraway, James Windsor
- Date: 1994
- Subjects: Physics -- Study and teaching -- South Africa Language arts -- South Africa Written communication -- Study and teaching -- South Africa Language arts -- Correlation with content subjects -- South Africa Physics teachers -- Language
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1693 , http://hdl.handle.net/10962/d1003576
- Description: The research was concerned with perceptions of language and physics in three strata of participants in a writing across the curriculum teaching course at an intermediate college. The participants were: a language teacher, two physics teachers and a class of twenty physics students - the students were studying in order to enter the Engineering Faculty at the University of Cape Town. The predominant understanding of the teachers was that of a limited interpenetration between the discourse of physics and language teaching. Physics teachers thought that language teachers would experience difficulties with both the concepts and language of physics. In actual practice however, students and the language teacher managed physics knowledge with some degree of success in the language classroom. Some students understood writing as helping them to understand physics. However, the dominant understanding of language was that of knowing the appropriate language of physics for their teachers. An appropriate language understanding was seen as potentially problematic in that it could encourage an unquestioning or monodimensional approach to physics knowledge. As a way around this problem, it was suggested that language teachers teach students to recognise and to use particular genres within science, and to develop their voice within these constraints.
- Full Text:
- Date Issued: 1994
Comparative aspects of the reproductive biology of seabreams (Pisces: Sparidae)
- Authors: Garratt, Patrick Ashworth
- Date: 1994
- Subjects: Sparidae -- Physiology Sparidae -- Reproduction
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5245 , http://hdl.handle.net/10962/d1005088
- Description: Sexuality in seabreams (Sparidae) is considered to be more complex than in any other family of fishes. Early work indicated five reproductive styles within the family: protandry, protogyny, simultaneous hermaphroditism, rudimentary hermaphroditism and gonochorism. More recently two reproductive styles have been suggested: sex change (protandry and protogyny) and secondary gonochorism (rudimentary hermaphrodites). The need for detailed descriptions of sex differentiation, gonad development and spawning behaviour in this family has been identified by a number of workers in this field. The aims of the present study were: i) to provide accurate, detailed descriptions and comparisons of gonadal development in representatives of each reproductive style, ii) to investigate their spawning strategies, and iii) to relate these findings to current theories on hermaphroditism and sex change in fishes. Four species were investigated. Slinger, Chrysoblephus puniceus, the only known protogynous hermaphrodite in Natal. Santer, Cheimerius nufar, described in the literature as a rudimentary hermaphrodite. Riverbream, Acanthopagrus berda suspected to be a protandrous hermaphrodite. Natal stump nose, Rhabdosargus sarba, reported elsewhere as a protandrous hermaphrodite. Detailed histological analysis showed that morphological and cytological development of all gonads proceeded initially in a female direction, irrespective of reproductive style, but that differentiating gonads of protandrous and protogynous hermaphrodites could easily be distinguished from one another. Early gonadal development was similar in R. sarba and A. berda with gonadal primordia differentiating into distinctly bisexual organs. In C. puniceus and C. nufar gonadal primordia differentiated into ovaries with reduced, inert male elements in the tunica albuginea. Sex differentiation occurred relatively late (100-150mm fork length) in all the species investigated. Few cells conforming to primordial germ cells (PGC's) described in other teleosts were identified. These cells only became evident after the appearance of gonial cells and their identity is questioned. Gonial cells appeared to develop within less-electron-dense cysts of cells. Gonial cells in presumptive male and female elements could not be distinguished from one another morphologically, suggesting the bipotentiality of these cells. All R. sarba and A. berda gonads pass through a predominantly male phase and all fish function first as males, indicating protandrous sex change in both species. All C. puniceus and C. nufar gonads develop initially into ovaries. Sex change thus occurs in both species and protogyny in C. puniceus is confirmed. In C. nufar, sex change may occur before or after sexual maturity and its reproductive style remains uncertain. Investigations into the spawning habits of A. berda have shown that this species spawns inside the Kosi estuary at night. Eggs are released during peak ebb tides. Spawning occurs in large aggregations and several to many males compete to spawn with individual females. This spawning strategy does not conform to predictions made from the size advantage model for protandrous species. Chrysoblephus puniceus appears to have preferential spawning sites on down-current outer reef margins. Spawning was not observed in this species, but changes in behaviour, social structure and colour during the spawning season suggest that it may have a mating system similar to several protogynous labrids and scarids, in which territories are temporary. Cheimerius nufar has a similar mating system. Temporary territories are established by large males during the spawning season, which extends from August to November. Mating is by pair-spawning and dominant territorial males obtain a disproportionate number of matings. 'Streaking' appears to represent an alternative mating strategy for males until they attain a sufficient size to establish and defend territories. The mating pattern of C. nufar suggests that it is either a gonochorist which does not conform to current theoretical predictions; or that it is a protogynous hermaphrodite incorrectly diagnosed as a rudimentary hermaphrodite; or that protogyny in the Sparidae is an ancestral condition and C. nufar is in the process of evolutionary change from a protogynous to a gonochoristic form (or visa versa).
- Full Text:
- Date Issued: 1994
- Authors: Garratt, Patrick Ashworth
- Date: 1994
- Subjects: Sparidae -- Physiology Sparidae -- Reproduction
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5245 , http://hdl.handle.net/10962/d1005088
- Description: Sexuality in seabreams (Sparidae) is considered to be more complex than in any other family of fishes. Early work indicated five reproductive styles within the family: protandry, protogyny, simultaneous hermaphroditism, rudimentary hermaphroditism and gonochorism. More recently two reproductive styles have been suggested: sex change (protandry and protogyny) and secondary gonochorism (rudimentary hermaphrodites). The need for detailed descriptions of sex differentiation, gonad development and spawning behaviour in this family has been identified by a number of workers in this field. The aims of the present study were: i) to provide accurate, detailed descriptions and comparisons of gonadal development in representatives of each reproductive style, ii) to investigate their spawning strategies, and iii) to relate these findings to current theories on hermaphroditism and sex change in fishes. Four species were investigated. Slinger, Chrysoblephus puniceus, the only known protogynous hermaphrodite in Natal. Santer, Cheimerius nufar, described in the literature as a rudimentary hermaphrodite. Riverbream, Acanthopagrus berda suspected to be a protandrous hermaphrodite. Natal stump nose, Rhabdosargus sarba, reported elsewhere as a protandrous hermaphrodite. Detailed histological analysis showed that morphological and cytological development of all gonads proceeded initially in a female direction, irrespective of reproductive style, but that differentiating gonads of protandrous and protogynous hermaphrodites could easily be distinguished from one another. Early gonadal development was similar in R. sarba and A. berda with gonadal primordia differentiating into distinctly bisexual organs. In C. puniceus and C. nufar gonadal primordia differentiated into ovaries with reduced, inert male elements in the tunica albuginea. Sex differentiation occurred relatively late (100-150mm fork length) in all the species investigated. Few cells conforming to primordial germ cells (PGC's) described in other teleosts were identified. These cells only became evident after the appearance of gonial cells and their identity is questioned. Gonial cells appeared to develop within less-electron-dense cysts of cells. Gonial cells in presumptive male and female elements could not be distinguished from one another morphologically, suggesting the bipotentiality of these cells. All R. sarba and A. berda gonads pass through a predominantly male phase and all fish function first as males, indicating protandrous sex change in both species. All C. puniceus and C. nufar gonads develop initially into ovaries. Sex change thus occurs in both species and protogyny in C. puniceus is confirmed. In C. nufar, sex change may occur before or after sexual maturity and its reproductive style remains uncertain. Investigations into the spawning habits of A. berda have shown that this species spawns inside the Kosi estuary at night. Eggs are released during peak ebb tides. Spawning occurs in large aggregations and several to many males compete to spawn with individual females. This spawning strategy does not conform to predictions made from the size advantage model for protandrous species. Chrysoblephus puniceus appears to have preferential spawning sites on down-current outer reef margins. Spawning was not observed in this species, but changes in behaviour, social structure and colour during the spawning season suggest that it may have a mating system similar to several protogynous labrids and scarids, in which territories are temporary. Cheimerius nufar has a similar mating system. Temporary territories are established by large males during the spawning season, which extends from August to November. Mating is by pair-spawning and dominant territorial males obtain a disproportionate number of matings. 'Streaking' appears to represent an alternative mating strategy for males until they attain a sufficient size to establish and defend territories. The mating pattern of C. nufar suggests that it is either a gonochorist which does not conform to current theoretical predictions; or that it is a protogynous hermaphrodite incorrectly diagnosed as a rudimentary hermaphrodite; or that protogyny in the Sparidae is an ancestral condition and C. nufar is in the process of evolutionary change from a protogynous to a gonochoristic form (or visa versa).
- Full Text:
- Date Issued: 1994
The impact of the end of the Cold War on transition in South Africa
- Authors: Du Preez, Roni
- Date: 1994
- Subjects: Cold War , International relations , South Africa -- Politics and government -- 1989-1994 , South Africa -- Foreign relations -- 1989-1994 , South Africa -- Politics and government -- 1978-1989 , South Africa -- Foreign relations -- 1978-1989
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2773 , http://hdl.handle.net/10962/d1002983 , Cold War , International relations , South Africa -- Politics and government -- 1989-1994 , South Africa -- Foreign relations -- 1989-1994 , South Africa -- Politics and government -- 1978-1989 , South Africa -- Foreign relations -- 1978-1989
- Description: This thesis argues that F.W. de Klerk's historic February 1990 speech was the end product of a set of circumstances in recent South African and global history which made possible the new phase of transitional politics which South Africa is currently experiencing. It seeks to establish that of all the factors that contributed to change, it was the late 1980s thaw in the Cold War, and its resultant repercussions internationally and regionally which was the catalytic factor which made the new era possible. In all the literature on transition there has been no comprehensive analysis of the plausible link between the two superpowers agreeing in the mid-1980s to abandon confrontational practices and to change their approaches to regional conflicts and the South African government agreeing to negotiate for a new political dispensation. This thesis will seek to establish and analyse such a link. By 1986 there was in certain governmental circles a non-public view that the policy of apartheid had failed both as a solution to the problem of black political aspirations and as a legitimating ideology. Constraining any serious move towards political change was a widely held fear at the top level of government that an accelerated reform process would make South Africa vulnerable to external aggression and internal revolutionary forces. This thesis suggests that the collapse of communist rule in Eastern Europe and the 'new political thinking' in Soviet foreign policy resulted in the notion of a communist-inspired total onslaught against South Africa losing currency - as did the position of those within the ruling elite who remained dogmatically attached to it. The end of the Cold War is the common thread which links South Africa's international , regional and domestic environments. Two important events occurred in the international and regional arenas, which against the backdrop of the end of the Cold War, strengthened the credibility of the alternative view in government: (i) the October 1986 Reykjavik Summit and (ii) the South African Defence Force setback at Cuito Cuanavale. P.W. Botha's resignation as leader of the National Party and soon after as State President created the political space through which the view of the reformers could emerge as dominant. Recognising that neither the international nor regional environments sustained the beliefs and fears held by the military hawks, F.W. de Klerk was able to capitalise on the ambience of negotiations and apply it to the South African situation. De Klerk's February 1990 speech was therefore the culmination of a process which had its origins in the mid-1980's.
- Full Text:
- Date Issued: 1994
- Authors: Du Preez, Roni
- Date: 1994
- Subjects: Cold War , International relations , South Africa -- Politics and government -- 1989-1994 , South Africa -- Foreign relations -- 1989-1994 , South Africa -- Politics and government -- 1978-1989 , South Africa -- Foreign relations -- 1978-1989
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2773 , http://hdl.handle.net/10962/d1002983 , Cold War , International relations , South Africa -- Politics and government -- 1989-1994 , South Africa -- Foreign relations -- 1989-1994 , South Africa -- Politics and government -- 1978-1989 , South Africa -- Foreign relations -- 1978-1989
- Description: This thesis argues that F.W. de Klerk's historic February 1990 speech was the end product of a set of circumstances in recent South African and global history which made possible the new phase of transitional politics which South Africa is currently experiencing. It seeks to establish that of all the factors that contributed to change, it was the late 1980s thaw in the Cold War, and its resultant repercussions internationally and regionally which was the catalytic factor which made the new era possible. In all the literature on transition there has been no comprehensive analysis of the plausible link between the two superpowers agreeing in the mid-1980s to abandon confrontational practices and to change their approaches to regional conflicts and the South African government agreeing to negotiate for a new political dispensation. This thesis will seek to establish and analyse such a link. By 1986 there was in certain governmental circles a non-public view that the policy of apartheid had failed both as a solution to the problem of black political aspirations and as a legitimating ideology. Constraining any serious move towards political change was a widely held fear at the top level of government that an accelerated reform process would make South Africa vulnerable to external aggression and internal revolutionary forces. This thesis suggests that the collapse of communist rule in Eastern Europe and the 'new political thinking' in Soviet foreign policy resulted in the notion of a communist-inspired total onslaught against South Africa losing currency - as did the position of those within the ruling elite who remained dogmatically attached to it. The end of the Cold War is the common thread which links South Africa's international , regional and domestic environments. Two important events occurred in the international and regional arenas, which against the backdrop of the end of the Cold War, strengthened the credibility of the alternative view in government: (i) the October 1986 Reykjavik Summit and (ii) the South African Defence Force setback at Cuito Cuanavale. P.W. Botha's resignation as leader of the National Party and soon after as State President created the political space through which the view of the reformers could emerge as dominant. Recognising that neither the international nor regional environments sustained the beliefs and fears held by the military hawks, F.W. de Klerk was able to capitalise on the ambience of negotiations and apply it to the South African situation. De Klerk's February 1990 speech was therefore the culmination of a process which had its origins in the mid-1980's.
- Full Text:
- Date Issued: 1994