The role of drinking fathers in later contradictions and choices in the lives of married women
- Authors: Meyer, Jennifer Anne
- Date: 1997
- Subjects: Adult children of alcoholics -- Psychology
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3018 , http://hdl.handle.net/10962/d1002527 , Adult children of alcoholics -- Psychology
- Description: This qualitative, interpretive research sought to elicit explanations for certain contradictions and choices in the lives of four married women who were autonomous and assertive in their careers, yet non-assertive and compliant in their married lives. Such contradictions appeared both in their projected stories and semi-structured interviews. It had been expected that these projected stories would reveal autonomy and assertiveness, in line with the white, middle-class, feminist values of the subjects, but they had not. Explanations for these apparent contradictions were attributed to the effects of being children of alcoholic fathers. While the subjects' socialisation and vulnerability to family ideology provided certain explanations for the presence of such contradictions, an object relations account of the unconscious need to resurrect an ideal father and repair the generic family provided a more probable explanation,and accounted for their traditional gender role behaviour as ideal wives in spite of their non-traditional, feminist behaviour outside of marriage.
- Full Text:
- Date Issued: 1997
- Authors: Meyer, Jennifer Anne
- Date: 1997
- Subjects: Adult children of alcoholics -- Psychology
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3018 , http://hdl.handle.net/10962/d1002527 , Adult children of alcoholics -- Psychology
- Description: This qualitative, interpretive research sought to elicit explanations for certain contradictions and choices in the lives of four married women who were autonomous and assertive in their careers, yet non-assertive and compliant in their married lives. Such contradictions appeared both in their projected stories and semi-structured interviews. It had been expected that these projected stories would reveal autonomy and assertiveness, in line with the white, middle-class, feminist values of the subjects, but they had not. Explanations for these apparent contradictions were attributed to the effects of being children of alcoholic fathers. While the subjects' socialisation and vulnerability to family ideology provided certain explanations for the presence of such contradictions, an object relations account of the unconscious need to resurrect an ideal father and repair the generic family provided a more probable explanation,and accounted for their traditional gender role behaviour as ideal wives in spite of their non-traditional, feminist behaviour outside of marriage.
- Full Text:
- Date Issued: 1997
Epithermal precious metal deposits physicochemical constraints, classification characteristics and exploration guidelines
- Authors: McIver, Donald A
- Date: 1997
- Subjects: Precious metals , Geothermal resources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4941 , http://hdl.handle.net/10962/d1005553 , Precious metals , Geothermal resources
- Description: Epithermal deposits include a broad range of precious metal, base metal, mercury, and stibnite deposits. These deposits exhibit a low temperature of formation (180-280°C) at pressures of less than a few hundred bars (equivalent to depths of 1.5 - 2.0lkm). Epithermal gold deposits are the product of large-scale hydrothermal systems which mostly occur in convergent plate margin settings. Associated volcanism is largely of andesitic arc (calcalkaline to alkaline), or rhyolitic back-arc type. Porphyry Cu-Mo-Au deposits form deeper in the same systems. Genetic processes within individual deposits take place in an extremely complex manner. The resultant mineral associations, alteration styles and metal deposition patterns are even more complicated. Many attempts have been made to classify epithermal deposits based on mineralogy and alteration, host rocks, deposit form, genetic models, and standard deposits. For the explorationist, the most useful classification schemes should be brief, simple, descriptive, observationally based, and informative. Ultimately, two distinct styles of epithermal gold deposits are readily recognised: high-sulphidation, acid sulphate and low-sulphidation, adularia-sericite types. The terms high-sulphidation (HS) and low-sulphidation (IS) are based on the sulphidation state of associated sulphide minerals, which, along with characteristic hydrothermal alteration, reflect fundamental chemical differences in the epithermal environment. Highsulphidation-type deposits form in the root zones of volcanic domes from acid waters that contain residual magmatic volatiles. The low-sulphidation-type deposits form in geothermal systems where surficial waters mix with deeper, heated saline waters in a lateral flow regime, where neutral to weakly acidic, alkali chloride waters are dominant. The HSILS classification, combined with a simple description of the form of the deposit, conveys a large amount of information on mineralogy, alteration, and spatial characteristics of the mineralisation, and allows inferences to be drawn regarding likely regional controls, and the characteristics of the ore-forming fluids. The modern understanding of these environments allows us to quite effectively identify the most probable foci of mineral deposition in any given district. Current knowledge of these deposits has been derived from studies of active geothermal systems. Through comparison with alteration zones within these systems, the exploration geologist may determine the potential distribution and types of ore in a fossil geothermal system. Alteration zoning specifically can be used as a guide towards the most prospective part of the system. Epithermal gold deposits of both HS- and LS-styles are nevertheless profoundly difficult exploration targets. Successful exploration must rely on the integration of a variety of exploration techniques, guided by an understanding of the characteristics of the deposits and the processes that form them. There are no simple formulae for success in epithermal exploration: what works best must be determined for each terrain and each prospect. On a regional scale tectonic, igneous and structural settings can be used, together with assessment of the depth of erosion, to select areas for project area scale exploration. Integrated geological-geophysical interpretation derived from airborne geophysics providesa basis of targeting potential ore environments for follow-up. Geology, geochemistry and surface geophysics localise mineral concentrations within these target areas
- Full Text:
- Date Issued: 1997
- Authors: McIver, Donald A
- Date: 1997
- Subjects: Precious metals , Geothermal resources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4941 , http://hdl.handle.net/10962/d1005553 , Precious metals , Geothermal resources
- Description: Epithermal deposits include a broad range of precious metal, base metal, mercury, and stibnite deposits. These deposits exhibit a low temperature of formation (180-280°C) at pressures of less than a few hundred bars (equivalent to depths of 1.5 - 2.0lkm). Epithermal gold deposits are the product of large-scale hydrothermal systems which mostly occur in convergent plate margin settings. Associated volcanism is largely of andesitic arc (calcalkaline to alkaline), or rhyolitic back-arc type. Porphyry Cu-Mo-Au deposits form deeper in the same systems. Genetic processes within individual deposits take place in an extremely complex manner. The resultant mineral associations, alteration styles and metal deposition patterns are even more complicated. Many attempts have been made to classify epithermal deposits based on mineralogy and alteration, host rocks, deposit form, genetic models, and standard deposits. For the explorationist, the most useful classification schemes should be brief, simple, descriptive, observationally based, and informative. Ultimately, two distinct styles of epithermal gold deposits are readily recognised: high-sulphidation, acid sulphate and low-sulphidation, adularia-sericite types. The terms high-sulphidation (HS) and low-sulphidation (IS) are based on the sulphidation state of associated sulphide minerals, which, along with characteristic hydrothermal alteration, reflect fundamental chemical differences in the epithermal environment. Highsulphidation-type deposits form in the root zones of volcanic domes from acid waters that contain residual magmatic volatiles. The low-sulphidation-type deposits form in geothermal systems where surficial waters mix with deeper, heated saline waters in a lateral flow regime, where neutral to weakly acidic, alkali chloride waters are dominant. The HSILS classification, combined with a simple description of the form of the deposit, conveys a large amount of information on mineralogy, alteration, and spatial characteristics of the mineralisation, and allows inferences to be drawn regarding likely regional controls, and the characteristics of the ore-forming fluids. The modern understanding of these environments allows us to quite effectively identify the most probable foci of mineral deposition in any given district. Current knowledge of these deposits has been derived from studies of active geothermal systems. Through comparison with alteration zones within these systems, the exploration geologist may determine the potential distribution and types of ore in a fossil geothermal system. Alteration zoning specifically can be used as a guide towards the most prospective part of the system. Epithermal gold deposits of both HS- and LS-styles are nevertheless profoundly difficult exploration targets. Successful exploration must rely on the integration of a variety of exploration techniques, guided by an understanding of the characteristics of the deposits and the processes that form them. There are no simple formulae for success in epithermal exploration: what works best must be determined for each terrain and each prospect. On a regional scale tectonic, igneous and structural settings can be used, together with assessment of the depth of erosion, to select areas for project area scale exploration. Integrated geological-geophysical interpretation derived from airborne geophysics providesa basis of targeting potential ore environments for follow-up. Geology, geochemistry and surface geophysics localise mineral concentrations within these target areas
- Full Text:
- Date Issued: 1997
Newspapers in education programmes and South African youth: a survey of the relationship between South African school-goers and newspapers in Esikhawini, Kwazulu-Natal
- Authors: McComb, Roslin Vanessa
- Date: 1997
- Subjects: Newspapers in education -- South Africa , School children -- South Africa -- KwaZulu-Natal -- esikhawini , Newspapers in education
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3465 , http://hdl.handle.net/10962/d1002920 , Newspapers in education -- South Africa , School children -- South Africa -- KwaZulu-Natal -- esikhawini , Newspapers in education
- Description: This study examines the relationship which scholars have with newspapers against the background of a Newspapers in Education (NIE) programme in two black South African primary schools. Considering the presence of newspapers in the class as a medium of instruction, a number of factors are found to influence the -relationship which scholars have with newspapers. These factors are: scholars' access to newspapers; the nature of lessons using the newspaper; the character of the newspaper used in NIE and the context of education at the particular schools, including the attitudes and organisational abilities of both teachers and the principal. A description and analysis of this relationship is conducted in terms of the knowledge, attitudes and behaviour which scholars had -in te1ation to newspapers. This research is qualitative, undertaken from a constructivist-interpretative approach, and is set within international and South African contexts. The findings are relevant to understanding NIE programmes' interface with scholars' educational performance and with newspaper marketing objectives, as well as to the theorisation of NIE practices.
- Full Text:
- Date Issued: 1997
- Authors: McComb, Roslin Vanessa
- Date: 1997
- Subjects: Newspapers in education -- South Africa , School children -- South Africa -- KwaZulu-Natal -- esikhawini , Newspapers in education
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3465 , http://hdl.handle.net/10962/d1002920 , Newspapers in education -- South Africa , School children -- South Africa -- KwaZulu-Natal -- esikhawini , Newspapers in education
- Description: This study examines the relationship which scholars have with newspapers against the background of a Newspapers in Education (NIE) programme in two black South African primary schools. Considering the presence of newspapers in the class as a medium of instruction, a number of factors are found to influence the -relationship which scholars have with newspapers. These factors are: scholars' access to newspapers; the nature of lessons using the newspaper; the character of the newspaper used in NIE and the context of education at the particular schools, including the attitudes and organisational abilities of both teachers and the principal. A description and analysis of this relationship is conducted in terms of the knowledge, attitudes and behaviour which scholars had -in te1ation to newspapers. This research is qualitative, undertaken from a constructivist-interpretative approach, and is set within international and South African contexts. The findings are relevant to understanding NIE programmes' interface with scholars' educational performance and with newspaper marketing objectives, as well as to the theorisation of NIE practices.
- Full Text:
- Date Issued: 1997
A new empirical model for the peak ionospheric electron density using neural networks
- Authors: McKinnell, L A
- Date: 1997
- Subjects: Ionospheric electron density Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5478 , http://hdl.handle.net/10962/d1005264
- Description: This thesis describes the search for a temporal model for predicting the peak ionospheric electron density-(foF2). Existing models, such as the International Reference Ionosphere (IRI) and 8KYCOM, were used to predict the 12 noon foF2 value over Grahamstown (26°E, 33°8). An attempt was then made to find a model that would improve upon these results. The traditional method of linear regression was used as a first step towards a new model. It was found that this would involve a multi variable regression that is reliant on guessing the optimum variables to be used in the final equation. An extremely complicated modelling equation involving many terms would result. Neural networks (NNs) are introduced as a new technique for predicting foF2. They are also applied, for the first time, to the problem of determining the best predictors of foF2. This quantity depends upon day number, level of solar activity and level of magnetic activity. The optimum averaging lengths of the solar activity index and the magnetic activity index were determined by appling NNs, using the criterion that the best indices are those that give the lowest rms error between the measured and predicted foF2. The optimum index for solar activity was found to be a 2-month running mean value of the daily sunspot number and for magnetic activity a 2-day averaged A index was found to be optimum. In addition, it was found that the response of foF2 to magnetic activity changes is highly non-linear and seasonally dependent. Using these indices as inputs, the NN trained successfully to predict foF2 with an rms error of 0.946 MHz on the daily testing values. Comparison with the IRI showed an improvement of 40% on the rms error. It is also shown that the NN will predict the noon value of foF2 to the same level of accuracy for unseen data of the same type.
- Full Text:
- Date Issued: 1997
- Authors: McKinnell, L A
- Date: 1997
- Subjects: Ionospheric electron density Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5478 , http://hdl.handle.net/10962/d1005264
- Description: This thesis describes the search for a temporal model for predicting the peak ionospheric electron density-(foF2). Existing models, such as the International Reference Ionosphere (IRI) and 8KYCOM, were used to predict the 12 noon foF2 value over Grahamstown (26°E, 33°8). An attempt was then made to find a model that would improve upon these results. The traditional method of linear regression was used as a first step towards a new model. It was found that this would involve a multi variable regression that is reliant on guessing the optimum variables to be used in the final equation. An extremely complicated modelling equation involving many terms would result. Neural networks (NNs) are introduced as a new technique for predicting foF2. They are also applied, for the first time, to the problem of determining the best predictors of foF2. This quantity depends upon day number, level of solar activity and level of magnetic activity. The optimum averaging lengths of the solar activity index and the magnetic activity index were determined by appling NNs, using the criterion that the best indices are those that give the lowest rms error between the measured and predicted foF2. The optimum index for solar activity was found to be a 2-month running mean value of the daily sunspot number and for magnetic activity a 2-day averaged A index was found to be optimum. In addition, it was found that the response of foF2 to magnetic activity changes is highly non-linear and seasonally dependent. Using these indices as inputs, the NN trained successfully to predict foF2 with an rms error of 0.946 MHz on the daily testing values. Comparison with the IRI showed an improvement of 40% on the rms error. It is also shown that the NN will predict the noon value of foF2 to the same level of accuracy for unseen data of the same type.
- Full Text:
- Date Issued: 1997
Responding to literature: empowering girls to speak with their own voices in a multicultural context
- Authors: Foster, Lesley
- Date: 1997
- Subjects: Reader-response criticism--South Africa Multicultural education
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1742 , http://hdl.handle.net/10962/d1003626
- Description: The purpose of this study was to investigate whether the space provided by a readerresponse transaction between girls and the text, Roll of Thunder, Hear My Cry (Taylor 1977) .. empowered pupils to tell their own stories. It also sought to identify ways in which the problems and possibilities perceived by these pupils might guide curriculum decisions in a transforming education system. In addition to engaging in reader-response activities around the text, drama and videos providing social context were integral to the programme. Related work in the subject areas of history and lifeskills was also undertaken. Data was drawn from pupils' reading journals, responses to specific passages, transcripts of small group discussions, and interviews. The study is ethnographic in nature and all the data qualitative. Theoretical insights were drawn from the felds of cultural studies, postmodern criticism, and postructural modes of cultural and social analysis inasfar as they illuminate and inform the relationship between language, knowledge and power. The research was conducted in an historically white, girls' school which adopted a nonracial admissions policy in January 1991. Despite the fact that existing traditions and values of the the school to a very large extent influence what is taught, the data suggests that pupils were becoming agents in their own learning and were taking up multiple identities both within and without the world of the school.
- Full Text:
- Date Issued: 1997
Responding to literature: empowering girls to speak with their own voices in a multicultural context
- Authors: Foster, Lesley
- Date: 1997
- Subjects: Reader-response criticism--South Africa Multicultural education
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1742 , http://hdl.handle.net/10962/d1003626
- Description: The purpose of this study was to investigate whether the space provided by a readerresponse transaction between girls and the text, Roll of Thunder, Hear My Cry (Taylor 1977) .. empowered pupils to tell their own stories. It also sought to identify ways in which the problems and possibilities perceived by these pupils might guide curriculum decisions in a transforming education system. In addition to engaging in reader-response activities around the text, drama and videos providing social context were integral to the programme. Related work in the subject areas of history and lifeskills was also undertaken. Data was drawn from pupils' reading journals, responses to specific passages, transcripts of small group discussions, and interviews. The study is ethnographic in nature and all the data qualitative. Theoretical insights were drawn from the felds of cultural studies, postmodern criticism, and postructural modes of cultural and social analysis inasfar as they illuminate and inform the relationship between language, knowledge and power. The research was conducted in an historically white, girls' school which adopted a nonracial admissions policy in January 1991. Despite the fact that existing traditions and values of the the school to a very large extent influence what is taught, the data suggests that pupils were becoming agents in their own learning and were taking up multiple identities both within and without the world of the school.
- Full Text:
- Date Issued: 1997
Towards an understanding of Amayeza esiXhosa stores (African chemists): how they operate, and the services they offer in the Eastern Cape
- Authors: Cocks, Michelle L
- Date: 1997
- Subjects: Medical anthropology -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:2096 , http://hdl.handle.net/10962/d1002659 , Medical anthropology -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape
- Description: In medical anthropology there has been a tendency to dichotomize western biomedical . healtb services, on the one hand, and traditional health care practices on the other. Much attention has been focused on the comparison between these two approaches in the hope that they might be reconciled. The problem with this approach is twofold. In the first place, it has not always acknowledged the local, historic~1, political and economic contexts in which different approaches to health care have evolved and in the second place, health care services which belong to neither the western nor traditional healing spheres and which are driven by commercial interests have been almost completely neglected because they fall outside of the basic dichotomy. Amayeza stores have been a feature of South African towns and cities for many years. They mayor may not be run by Africans, but their clientele is almost exclusively African in this region. They deal in a bewildering variety of products and remedies, from untreated herbal and animal products to pharmaceuticals specially prepared for the African market, to Dutch and Indian Remedies. These stores both reflect transfonnations in indigenous perceptions of health care and, by virtue of the choices they offer, generate change. In this empirical study three stores in the Eastern Cape are selected for detailed study - two in King William's Town, the regional capital, and one in the small town of Peddie. The approach is holistic, emphasizing the social, political and economic context, the business histories and running of each shop, and, in particular, the perceptions and choices of a sample of the customers in each case. The success of the amayeza phenomenon derives from its eclecticism and syncretism. These stores impose neither a western nor a traditional model of health care on their clients, but offer them a range of choices that reflects the complex multicultural history of their own South African society.
- Full Text:
- Date Issued: 1997
- Authors: Cocks, Michelle L
- Date: 1997
- Subjects: Medical anthropology -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:2096 , http://hdl.handle.net/10962/d1002659 , Medical anthropology -- South Africa -- Eastern Cape , Traditional medicine -- South Africa -- Eastern Cape
- Description: In medical anthropology there has been a tendency to dichotomize western biomedical . healtb services, on the one hand, and traditional health care practices on the other. Much attention has been focused on the comparison between these two approaches in the hope that they might be reconciled. The problem with this approach is twofold. In the first place, it has not always acknowledged the local, historic~1, political and economic contexts in which different approaches to health care have evolved and in the second place, health care services which belong to neither the western nor traditional healing spheres and which are driven by commercial interests have been almost completely neglected because they fall outside of the basic dichotomy. Amayeza stores have been a feature of South African towns and cities for many years. They mayor may not be run by Africans, but their clientele is almost exclusively African in this region. They deal in a bewildering variety of products and remedies, from untreated herbal and animal products to pharmaceuticals specially prepared for the African market, to Dutch and Indian Remedies. These stores both reflect transfonnations in indigenous perceptions of health care and, by virtue of the choices they offer, generate change. In this empirical study three stores in the Eastern Cape are selected for detailed study - two in King William's Town, the regional capital, and one in the small town of Peddie. The approach is holistic, emphasizing the social, political and economic context, the business histories and running of each shop, and, in particular, the perceptions and choices of a sample of the customers in each case. The success of the amayeza phenomenon derives from its eclecticism and syncretism. These stores impose neither a western nor a traditional model of health care on their clients, but offer them a range of choices that reflects the complex multicultural history of their own South African society.
- Full Text:
- Date Issued: 1997
The application of a landscape diversity index using remote sensing and geographical information systems to identify degradation patterns in the Great Fish River Valley, Eastern Cape Province, South Africa
- Authors: Tanser, Frank Courteney
- Date: 1997
- Subjects: Geographic information systems , Earth sciences -- Remote sensing , Environmental degradation -- South Africa -- Eastern Cape -- Great Fish River Valley , Forest degradation -- South Africa -- Eastern Cape -- Great Rish River Valley
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4814 , http://hdl.handle.net/10962/d1005488 , Geographic information systems , Earth sciences -- Remote sensing , Environmental degradation -- South Africa -- Eastern Cape -- Great Fish River Valley , Forest degradation -- South Africa -- Eastern Cape -- Great Rish River Valley
- Description: Using a range of satellite-derived indices I describe. monitor and predict vegetation conditions that exist in the Great Fish River Valley, Eastern Cape. The heterogeneous nature of the area necessitates that the mapping of vegetation classes be accomplished using a combination of a supervised approach, an unsupervised approach and the use of a Moving Standard Deviation Index (MSDI). Nine vegetation classes are identified and mapped at an accuracy of 84%. The vegetation classes are strongly related to land-use and the communal areas demonstrate a reduction in palatable species and a shift towards dominance by a single species. Nature reserves and commercial rangeland are by contrast dominated by good condition vegetation types. The Modified Soil Adjusted Vegetation Index (MSA VI) is used to map the vegetation production in the study area. The influence of soil reflectance is reduced using this index. The MSA VI proves to be a good predictor of vegetation condition in the higher rainfall areas but not in the more semi-arid regions. The MSA VI has a significant relationship to rainfall but no absolute relationship to biomass. However, a stratification approach (on the basis of vegetation type) reveals that the MSA VI exhibits relationships to biomass in vegetation types occurring in the higher rainfall areas and consisting of a large cover of shrubs. A technique based on an index which describes landscape spatial variability is presented to assist in the interpretation of landscape condition. The research outlines a method for degradation assessment which overcomes many of the problems associated with cost and repeatability. Indices that attempt to provide a correlation with net primary productivity, e.g. NDVI, do not consider changes in the quality of net primary productivity. Landscape variability represents a measure of ecosystem change in the landscape that underlies the degradation process. The hypothesis is that healthy/undisturbed/stable landscapes tend to be less variable and homogenous than their degraded heterogenous counterparts. The Moving Standard Deviation Index (MSDI) is calculated by performing a 3 x 3 moving standard deviation window across Landsat Thematic Mapper (TM) band 3. The result is a sensitive indicator of landscape condition which is not affected by moisture availability and vegetation type. The MSDI shows a significant negative relationship to NDVI confirming its relationship to condition. The cross-classification of MSDI with NDVI allows the identification of invasive woody weeds which exhibit strong photosynthetic signals and would therefore be categorised as good condition using NDVI. Other ecosystems are investigated to determine the relationship between NDVI and MSDI. Where increase in NDVI is disturbance-induced (such as the Kalahari Desert) the relationship is positive. Where high NDVI values are indicative of good condition rangeland (such as the Fish River Valley) the relationship is negative. The MSDI therefore always exhibits a significant positive relationship to degradation irrespective of the relationship of NDVI to condition in the ecosystem.
- Full Text:
- Date Issued: 1997
- Authors: Tanser, Frank Courteney
- Date: 1997
- Subjects: Geographic information systems , Earth sciences -- Remote sensing , Environmental degradation -- South Africa -- Eastern Cape -- Great Fish River Valley , Forest degradation -- South Africa -- Eastern Cape -- Great Rish River Valley
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4814 , http://hdl.handle.net/10962/d1005488 , Geographic information systems , Earth sciences -- Remote sensing , Environmental degradation -- South Africa -- Eastern Cape -- Great Fish River Valley , Forest degradation -- South Africa -- Eastern Cape -- Great Rish River Valley
- Description: Using a range of satellite-derived indices I describe. monitor and predict vegetation conditions that exist in the Great Fish River Valley, Eastern Cape. The heterogeneous nature of the area necessitates that the mapping of vegetation classes be accomplished using a combination of a supervised approach, an unsupervised approach and the use of a Moving Standard Deviation Index (MSDI). Nine vegetation classes are identified and mapped at an accuracy of 84%. The vegetation classes are strongly related to land-use and the communal areas demonstrate a reduction in palatable species and a shift towards dominance by a single species. Nature reserves and commercial rangeland are by contrast dominated by good condition vegetation types. The Modified Soil Adjusted Vegetation Index (MSA VI) is used to map the vegetation production in the study area. The influence of soil reflectance is reduced using this index. The MSA VI proves to be a good predictor of vegetation condition in the higher rainfall areas but not in the more semi-arid regions. The MSA VI has a significant relationship to rainfall but no absolute relationship to biomass. However, a stratification approach (on the basis of vegetation type) reveals that the MSA VI exhibits relationships to biomass in vegetation types occurring in the higher rainfall areas and consisting of a large cover of shrubs. A technique based on an index which describes landscape spatial variability is presented to assist in the interpretation of landscape condition. The research outlines a method for degradation assessment which overcomes many of the problems associated with cost and repeatability. Indices that attempt to provide a correlation with net primary productivity, e.g. NDVI, do not consider changes in the quality of net primary productivity. Landscape variability represents a measure of ecosystem change in the landscape that underlies the degradation process. The hypothesis is that healthy/undisturbed/stable landscapes tend to be less variable and homogenous than their degraded heterogenous counterparts. The Moving Standard Deviation Index (MSDI) is calculated by performing a 3 x 3 moving standard deviation window across Landsat Thematic Mapper (TM) band 3. The result is a sensitive indicator of landscape condition which is not affected by moisture availability and vegetation type. The MSDI shows a significant negative relationship to NDVI confirming its relationship to condition. The cross-classification of MSDI with NDVI allows the identification of invasive woody weeds which exhibit strong photosynthetic signals and would therefore be categorised as good condition using NDVI. Other ecosystems are investigated to determine the relationship between NDVI and MSDI. Where increase in NDVI is disturbance-induced (such as the Kalahari Desert) the relationship is positive. Where high NDVI values are indicative of good condition rangeland (such as the Fish River Valley) the relationship is negative. The MSDI therefore always exhibits a significant positive relationship to degradation irrespective of the relationship of NDVI to condition in the ecosystem.
- Full Text:
- Date Issued: 1997
Effects of sustained elevated CO₂ concentration on two cultivars of barley (Hordeum vulgare L.)
- Authors: Siphugu, Mashudu Victor
- Date: 1997
- Subjects: Barley Barley -- Growth Photosynthesis -- Research Plants -- Effect of carbon dioxide on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4226 , http://hdl.handle.net/10962/d1003795
- Description: The enormous burning of fossil fuel and deforestation have caused an increase in the atmospheric CO₂ concentration ([CO₂]) during the last century. This will invariably have profound direct and indirect effects on plant carbon metabolism. The majority of research on the effects of CO₂ enrichment on plants are short-term and are done on other crops, but very little have been done on barley. This project aimed to determine the effects of long-term CO₂ enrichment on photosynthesis, growth and grain yield on barley. Hordeum vulgare L. cvs Stirling and Schooner plants were grown from seeds in controlled environment chambers at ambient (350) and elevated (600) μmol molˉ¹ [CO₂]. Measurements of net assimilation rate (NAR), photosynthetic pigments content and growth parameters were started 7 days after germination (DAG) and continued until senescence. The anatomy of matured fully developed leaves was also monitored. Elevated [CO₂l resulted in an increase in NAR in the two cultivars from days 7 until 14, after which the stimulation of NAR of CO₂-enriched plants started to decrease. At the onset of senescence, NAR was almost equal in plants grown under both ambient and elevated [CO₂]. The response of assimilation as a function of internal [CO₂l (C₁) at the end of the experimental period showed a significant decrease in both the initial slope of the A/C₁ curves and the CO₂-saturated photosynthetic rates in the two cultivars. Stirling showed no significant changes in the content of chlorophyll α,chlorophyll б or in total carotenoids. However, Schooner showed a stimulation in chlorophyll α content at day 7, but decreased at day 28. Chlorophyll б and total carotenoids content were not affected by CO₂ enrichment. While total above-ground biomass was not affected by elevated [CO₂] in the two cultivars, total plant height decreased significantly after 14 days in Stirling whereas no significant change occurred in Schooner throughout the experimental period. Leaf area was not significantly affected by CO₂ enrichment in the two cultivars although the leaves in CO₂ enriched plants were slightly shorter. Anatomical studies reveal that leaf thickness was significantly increased by CO₂ enrichment in Stirling, but the increase was not significant in Schooner. Both cultivars did not show any significant effect on chloroplast morphology and ultrastructure as a consequence of elevated CO₂ exposure. No signs of starch accumulation were evident in variety Schooner, but Stirling showed some form of starch accumulation, under increased atmospheric [CO₂]. Elevated CO₂ resulted in a significant reduction by more than 50 % in the number of grain yield per plant in both Stirling and Schooner. Results from this study therefore indicate that CO₂ enrichment will not be beneficial in terms of growth and yield in this important crop.
- Full Text:
- Date Issued: 1997
- Authors: Siphugu, Mashudu Victor
- Date: 1997
- Subjects: Barley Barley -- Growth Photosynthesis -- Research Plants -- Effect of carbon dioxide on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4226 , http://hdl.handle.net/10962/d1003795
- Description: The enormous burning of fossil fuel and deforestation have caused an increase in the atmospheric CO₂ concentration ([CO₂]) during the last century. This will invariably have profound direct and indirect effects on plant carbon metabolism. The majority of research on the effects of CO₂ enrichment on plants are short-term and are done on other crops, but very little have been done on barley. This project aimed to determine the effects of long-term CO₂ enrichment on photosynthesis, growth and grain yield on barley. Hordeum vulgare L. cvs Stirling and Schooner plants were grown from seeds in controlled environment chambers at ambient (350) and elevated (600) μmol molˉ¹ [CO₂]. Measurements of net assimilation rate (NAR), photosynthetic pigments content and growth parameters were started 7 days after germination (DAG) and continued until senescence. The anatomy of matured fully developed leaves was also monitored. Elevated [CO₂l resulted in an increase in NAR in the two cultivars from days 7 until 14, after which the stimulation of NAR of CO₂-enriched plants started to decrease. At the onset of senescence, NAR was almost equal in plants grown under both ambient and elevated [CO₂]. The response of assimilation as a function of internal [CO₂l (C₁) at the end of the experimental period showed a significant decrease in both the initial slope of the A/C₁ curves and the CO₂-saturated photosynthetic rates in the two cultivars. Stirling showed no significant changes in the content of chlorophyll α,chlorophyll б or in total carotenoids. However, Schooner showed a stimulation in chlorophyll α content at day 7, but decreased at day 28. Chlorophyll б and total carotenoids content were not affected by CO₂ enrichment. While total above-ground biomass was not affected by elevated [CO₂] in the two cultivars, total plant height decreased significantly after 14 days in Stirling whereas no significant change occurred in Schooner throughout the experimental period. Leaf area was not significantly affected by CO₂ enrichment in the two cultivars although the leaves in CO₂ enriched plants were slightly shorter. Anatomical studies reveal that leaf thickness was significantly increased by CO₂ enrichment in Stirling, but the increase was not significant in Schooner. Both cultivars did not show any significant effect on chloroplast morphology and ultrastructure as a consequence of elevated CO₂ exposure. No signs of starch accumulation were evident in variety Schooner, but Stirling showed some form of starch accumulation, under increased atmospheric [CO₂]. Elevated CO₂ resulted in a significant reduction by more than 50 % in the number of grain yield per plant in both Stirling and Schooner. Results from this study therefore indicate that CO₂ enrichment will not be beneficial in terms of growth and yield in this important crop.
- Full Text:
- Date Issued: 1997
The use of remote sensing and Geographic Information System (GIS) techniques, to interpret savanna ecosystem patterns in the Sabi Sand Game Reserve, Mpumalanga province
- Fortescue, Alexander Kenneth John
- Authors: Fortescue, Alexander Kenneth John
- Date: 1997
- Subjects: Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4857 , http://hdl.handle.net/10962/d1005533 , Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Description: This thesis explores techniques which ultimately strive to optimize production systems in rangeland areas of southern Africa. By linking spatially significant, satellite derived data to practical measurements of vegetation structure, valuable insight has been derived on processes of ecosystem function, in the Sabi Sand Game Reserve. A broad ecosystem response mechanism has been established from a conventional Normalized Differentiation Vegetation Index (NDVI). By responding to increases in production, which are driven by disturbance, this index has allowed quantitative systems theory in savanna to be tested and refined. Methods of biomass and production estimation which are specifically designed to reduce the cost and time involved with the more conventional method of destructive harvesting have been tested in the savanna at the Sabi Sand Game Reserve. Results from these estimates relate well with data derived through destructive harvesting in structurally similar savanna. Moreover, by relating the above-ground woody production estimates to remere sensing indices, it was possible to demonstrate that the problem of extrapolation, universal to most biomass and production studies can be overcome. Since remote sensing encompasses an array of tools fundamental to rangeland inventory, monitoring and management, valuable spatially significant information pertaining to ecosystem structure and function has been provided for managers in the Sabi Sand Game Reserve.
- Full Text:
- Date Issued: 1997
- Authors: Fortescue, Alexander Kenneth John
- Date: 1997
- Subjects: Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4857 , http://hdl.handle.net/10962/d1005533 , Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Description: This thesis explores techniques which ultimately strive to optimize production systems in rangeland areas of southern Africa. By linking spatially significant, satellite derived data to practical measurements of vegetation structure, valuable insight has been derived on processes of ecosystem function, in the Sabi Sand Game Reserve. A broad ecosystem response mechanism has been established from a conventional Normalized Differentiation Vegetation Index (NDVI). By responding to increases in production, which are driven by disturbance, this index has allowed quantitative systems theory in savanna to be tested and refined. Methods of biomass and production estimation which are specifically designed to reduce the cost and time involved with the more conventional method of destructive harvesting have been tested in the savanna at the Sabi Sand Game Reserve. Results from these estimates relate well with data derived through destructive harvesting in structurally similar savanna. Moreover, by relating the above-ground woody production estimates to remere sensing indices, it was possible to demonstrate that the problem of extrapolation, universal to most biomass and production studies can be overcome. Since remote sensing encompasses an array of tools fundamental to rangeland inventory, monitoring and management, valuable spatially significant information pertaining to ecosystem structure and function has been provided for managers in the Sabi Sand Game Reserve.
- Full Text:
- Date Issued: 1997
Chemical studies of necic acid analogues
- Guthrie-Strachan, Jeffry James
- Authors: Guthrie-Strachan, Jeffry James
- Date: 1997
- Subjects: Organic acids , Chemistry, Organic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4425 , http://hdl.handle.net/10962/d1006909 , Organic acids , Chemistry, Organic
- Description: Various aldehydes have been reacted with methyl acrylate under Baylis-Hillman conditions, using DABCO as a catalyst, to afford a range of α-substituted acrylic esters containing an allylic hydroxy group. Selected Baylis-Hillman products have been brominated, hydrolysed and acetylated to afford substrates for the synthesis of necic acid analogues. The diastereo- and regioselectivity of nucleophilic attack, using sodium methylmercaptan, on the Baylis-Hillman products and selected brominated derivatives was investigated. The allylic hydroxy compounds favour conjugate addition with the generation of a new chiral centre, while the allylic bromo derivatives favour substitution (SN and SN') (S[subscript N] and S[subscript N]') with consequent loss of chirality. (E)-2-Isopropylcrotonic acid, a vital precursor in the synthesis of all stereoisomers of trachelanthic and viridifloric acid, was synthesised in an attempt to obtain the necic acid components required for total alkaloid synthesis of lycopsamine and its derivatives. This precursor and salicylic acid were then used to prepare esters of retronecine, a dihydroxy necine base obtained via extraction and consequent hydrolysis of retrorsine.
- Full Text:
- Date Issued: 1997
- Authors: Guthrie-Strachan, Jeffry James
- Date: 1997
- Subjects: Organic acids , Chemistry, Organic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4425 , http://hdl.handle.net/10962/d1006909 , Organic acids , Chemistry, Organic
- Description: Various aldehydes have been reacted with methyl acrylate under Baylis-Hillman conditions, using DABCO as a catalyst, to afford a range of α-substituted acrylic esters containing an allylic hydroxy group. Selected Baylis-Hillman products have been brominated, hydrolysed and acetylated to afford substrates for the synthesis of necic acid analogues. The diastereo- and regioselectivity of nucleophilic attack, using sodium methylmercaptan, on the Baylis-Hillman products and selected brominated derivatives was investigated. The allylic hydroxy compounds favour conjugate addition with the generation of a new chiral centre, while the allylic bromo derivatives favour substitution (SN and SN') (S[subscript N] and S[subscript N]') with consequent loss of chirality. (E)-2-Isopropylcrotonic acid, a vital precursor in the synthesis of all stereoisomers of trachelanthic and viridifloric acid, was synthesised in an attempt to obtain the necic acid components required for total alkaloid synthesis of lycopsamine and its derivatives. This precursor and salicylic acid were then used to prepare esters of retronecine, a dihydroxy necine base obtained via extraction and consequent hydrolysis of retrorsine.
- Full Text:
- Date Issued: 1997
Die ontwikkeling van 'n plattelandse tak van die ACVV 1900-1996
- Authors: du Plessis, Alette Marjorie
- Date: 1997
- Subjects: Afrikaanse Christelike Vrouevereniging -- History , Charities -- South Africa -- Eastern Cape -- Cradock -- History , Afrikaners -- South Africa -- Eastern Cape -- Cradock -- Charities -- History
- Language: Afrikaans
- Type: Thesis , Masters , MSocSc
- Identifier: vital:694 , http://hdl.handle.net/10962/d1006387 , Afrikaanse Christelike Vrouevereniging -- History , Charities -- South Africa -- Eastern Cape -- Cradock -- History , Afrikaners -- South Africa -- Eastern Cape -- Cradock -- Charities -- History
- Description: Die ACVV is een van die oudste gesinsorgorganisasies in Suid-Afrika en die oudste vrou-welsynsvereniging. Die organisasie is in 1904 gestig, maar dit word bewys dat dit in werklikheid ouer is. Die ontstaan is die gevolg van noodlenigingswerk wat in sovele Kaaplandse dorpe en stede aangepak is deur die Afrikaanse vroue om sover moontlik die smarte van die Anglo-Boere-oorlog te verlig. Dit was veral in die jare 1900 en 1902 toe plaaslike komitees in verskeie dorpe gestig is om eetware, klere en leesstof aan die krygsgevangenes in die kamp te stuur en later aan die vroue in konsentrasiekampe. Hieruit kan afgelei word dat die organisasie ontstaan het met oorlewing as oogmerk. Toe die oorlog verby is, het die begeerte posgevat om van hierdie komitees iets blywends te maak. Lambrechts en Theron (1959:31) bepaal dat daar drie tydperke onderskei word by die nagaan van die werksaamhede van die ACVV. In die bestudering van die plaaslike omstandighede word die stelling as waar bewys, maar word die tydperke aangepas om die situasie in 'n wyer spektrum waar te neem. Die eerste tydperk word hoofsaaklik gekenmerk deur die groei van die vereniging en die reelings wat getref is vir die doeltreffende organisasie van die werk wat verrig is deur vrywillige werkers. Die tweede tydperk val saam met 'n algehele nuwe benadering teenoor welsynswerk wat gevloei het uit die vermeerderde kennis en studie van Sosiale Wetenskappe en die vraagstuk van verarming in Suid-Afrika na die jare van droogte en depressie. 'n Derde tydperk is geëidentifiseer waarin die land tred gehou het met die wereldtendens waarin die staat 'n groter aandeel in welsynsdienste begin neem het. 'n Toenemende toepassing van die beleid van staatshulp aan partikuliere organisasies is 'n erkenning van staatsweë dat daar bepaalde take is wat beter deur hierdie organisasies vervul kan word. Dit het ACW-takke in staat gestel om maatskaplike werkers aan te stel in gesubsidieerde poste. Die ACVV se dienste het gedurig ontwikkeling getoon en het noodleniging, gesinsorgdienste, groepdienste en residensiële sorg ingesluit. Dienste het sekondêr ontwikkel en baie klem is op bejaardesorg geplaas wat onder andere die oprigting en bestuur van tehuise en dienssentrums tot gevolg gehad het. Gesinsorgwerk vorm die eintlike kern van die werksaamhede van die ACVV, want al sy ondernemings het ten doel die bevordering van 'n gesonde gesinslewe. Dienste van die vereniging aan die individuele gesinslid het steeds ten doel om beter by sy gesin, en gevolglik ook beter by die samelewing aan te pas. 'n Duidelike ontwikkeling word beskryf wat vanaf 1990 tot 'n punt van verdere veranderinge gedryf word deur omstandighede buite die ACVV. Die belangrikste hiervan is 'n dramatiese verandering in regeringsbeleid waarby die ACVV moes aansluit. Dit het wesentlike aanpassings meegebring op die gebied van werksarea en die kliêntesisteem, aangesien die ACVV in die verlede hoofsaaklik in die behoeftes van die blanke kultuurgroep voorsien het. Later het subsidievereistes die vereniging verhoed om buite hierdie beperkings te werk. Die aanpassings het egter nie tot gevolg gehad dat die vereniging doelstellings, waardes en norme moes laat vaar nie. Verskeie rolspelers is betrokke by praktiese en basiese dienslewering tot besluitneming op die hoogste vlak. Die ACVV se struktuur het grootliks dieselfde gebly met die Kongres as hoogste gesag. Die dienste van die Hoofbestuur het sodanig uitgebrei dat dit leiding kon bied aan takke op grondvlak. Dit is deurgaans duidelik dat die vrywillige werker binne die organisasie die kern en basis vorm waarop die vereniging voortbestaan. Die ACVV sal in die toekoms steeds In rol het om te vervul in 'n veranderde omgewing wat uitdagings bied vir dienslewering en waar uitgebreide behoeftes ten opsigte van maatskaplike ontwikkeling bestaan
- Full Text:
- Date Issued: 1997
- Authors: du Plessis, Alette Marjorie
- Date: 1997
- Subjects: Afrikaanse Christelike Vrouevereniging -- History , Charities -- South Africa -- Eastern Cape -- Cradock -- History , Afrikaners -- South Africa -- Eastern Cape -- Cradock -- Charities -- History
- Language: Afrikaans
- Type: Thesis , Masters , MSocSc
- Identifier: vital:694 , http://hdl.handle.net/10962/d1006387 , Afrikaanse Christelike Vrouevereniging -- History , Charities -- South Africa -- Eastern Cape -- Cradock -- History , Afrikaners -- South Africa -- Eastern Cape -- Cradock -- Charities -- History
- Description: Die ACVV is een van die oudste gesinsorgorganisasies in Suid-Afrika en die oudste vrou-welsynsvereniging. Die organisasie is in 1904 gestig, maar dit word bewys dat dit in werklikheid ouer is. Die ontstaan is die gevolg van noodlenigingswerk wat in sovele Kaaplandse dorpe en stede aangepak is deur die Afrikaanse vroue om sover moontlik die smarte van die Anglo-Boere-oorlog te verlig. Dit was veral in die jare 1900 en 1902 toe plaaslike komitees in verskeie dorpe gestig is om eetware, klere en leesstof aan die krygsgevangenes in die kamp te stuur en later aan die vroue in konsentrasiekampe. Hieruit kan afgelei word dat die organisasie ontstaan het met oorlewing as oogmerk. Toe die oorlog verby is, het die begeerte posgevat om van hierdie komitees iets blywends te maak. Lambrechts en Theron (1959:31) bepaal dat daar drie tydperke onderskei word by die nagaan van die werksaamhede van die ACVV. In die bestudering van die plaaslike omstandighede word die stelling as waar bewys, maar word die tydperke aangepas om die situasie in 'n wyer spektrum waar te neem. Die eerste tydperk word hoofsaaklik gekenmerk deur die groei van die vereniging en die reelings wat getref is vir die doeltreffende organisasie van die werk wat verrig is deur vrywillige werkers. Die tweede tydperk val saam met 'n algehele nuwe benadering teenoor welsynswerk wat gevloei het uit die vermeerderde kennis en studie van Sosiale Wetenskappe en die vraagstuk van verarming in Suid-Afrika na die jare van droogte en depressie. 'n Derde tydperk is geëidentifiseer waarin die land tred gehou het met die wereldtendens waarin die staat 'n groter aandeel in welsynsdienste begin neem het. 'n Toenemende toepassing van die beleid van staatshulp aan partikuliere organisasies is 'n erkenning van staatsweë dat daar bepaalde take is wat beter deur hierdie organisasies vervul kan word. Dit het ACW-takke in staat gestel om maatskaplike werkers aan te stel in gesubsidieerde poste. Die ACVV se dienste het gedurig ontwikkeling getoon en het noodleniging, gesinsorgdienste, groepdienste en residensiële sorg ingesluit. Dienste het sekondêr ontwikkel en baie klem is op bejaardesorg geplaas wat onder andere die oprigting en bestuur van tehuise en dienssentrums tot gevolg gehad het. Gesinsorgwerk vorm die eintlike kern van die werksaamhede van die ACVV, want al sy ondernemings het ten doel die bevordering van 'n gesonde gesinslewe. Dienste van die vereniging aan die individuele gesinslid het steeds ten doel om beter by sy gesin, en gevolglik ook beter by die samelewing aan te pas. 'n Duidelike ontwikkeling word beskryf wat vanaf 1990 tot 'n punt van verdere veranderinge gedryf word deur omstandighede buite die ACVV. Die belangrikste hiervan is 'n dramatiese verandering in regeringsbeleid waarby die ACVV moes aansluit. Dit het wesentlike aanpassings meegebring op die gebied van werksarea en die kliêntesisteem, aangesien die ACVV in die verlede hoofsaaklik in die behoeftes van die blanke kultuurgroep voorsien het. Later het subsidievereistes die vereniging verhoed om buite hierdie beperkings te werk. Die aanpassings het egter nie tot gevolg gehad dat die vereniging doelstellings, waardes en norme moes laat vaar nie. Verskeie rolspelers is betrokke by praktiese en basiese dienslewering tot besluitneming op die hoogste vlak. Die ACVV se struktuur het grootliks dieselfde gebly met die Kongres as hoogste gesag. Die dienste van die Hoofbestuur het sodanig uitgebrei dat dit leiding kon bied aan takke op grondvlak. Dit is deurgaans duidelik dat die vrywillige werker binne die organisasie die kern en basis vorm waarop die vereniging voortbestaan. Die ACVV sal in die toekoms steeds In rol het om te vervul in 'n veranderde omgewing wat uitdagings bied vir dienslewering en waar uitgebreide behoeftes ten opsigte van maatskaplike ontwikkeling bestaan
- Full Text:
- Date Issued: 1997
The African National Congress' foreign policy in transition: change or continuity, 1989-1994
- Machesa, Aubrey Mpho John Refiloe
- Authors: Machesa, Aubrey Mpho John Refiloe
- Date: 1997
- Subjects: African National Congress -- Foreign relations
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2797 , http://hdl.handle.net/10962/d1003007 , African National Congress -- Foreign relations
- Description: But the central focus will be to explore the foreign policy transition by reflecting the theory that even though international and regional political developments had an impact on the foreign policy transition of the ANC, the internal and domestic political struggles that had evolved during the same time-frame as both the international and regional political developments also had major contributions to the foreign policy transition of the movement. Within this context, the study will also explore the preliminary contours of a post-apartheid foreign policy as perceived by the ANC as to how the country will be reintegrated into the political and economic world order.
- Full Text:
- Date Issued: 1997
- Authors: Machesa, Aubrey Mpho John Refiloe
- Date: 1997
- Subjects: African National Congress -- Foreign relations
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2797 , http://hdl.handle.net/10962/d1003007 , African National Congress -- Foreign relations
- Description: But the central focus will be to explore the foreign policy transition by reflecting the theory that even though international and regional political developments had an impact on the foreign policy transition of the ANC, the internal and domestic political struggles that had evolved during the same time-frame as both the international and regional political developments also had major contributions to the foreign policy transition of the movement. Within this context, the study will also explore the preliminary contours of a post-apartheid foreign policy as perceived by the ANC as to how the country will be reintegrated into the political and economic world order.
- Full Text:
- Date Issued: 1997
The effect of work-hardening on the physical work capacity of manual labourers within South African industry
- Authors: Jacka, Karen-Louise
- Date: 1997
- Subjects: Human engineering , Industrial accidents -- South Africa , Industrial safety -- South Africa , Musculoskeletal system -- Wounds and injuries
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5165 , http://hdl.handle.net/10962/d1016237
- Description: South Africa is a labour-intensive industrially developing country. As a result, in excess of 200 000 workers suffer from musculoskeletal injuries in a year. Research is thus essential to develop more effective strategies in the reduction and rehabilitation of occupational musculoskeletal disorders within industry. It was the hypothesis of this study that by improving the physical work capacity of manual labourers, through participation in an occupation specific work-hardening programme, that the ergonomic stress index and therefore the occurrence of musculoskeletal injuries within industry, may be reduced. Twenty-five male Black and Coloured manual labourers volunteered to participate in this study. In addition to in situ task analyses, the subjects participated in cardiovascular and strength assessments in the laboratory, both pre- and post-participation in the ten-week work-hardening programme. The data were statistically analyzed in order to identify any significant • improvements in the workers' physical work capacity, as measured by cardiovascular, strength and perceptual responses, following the period of work-hardening. Two significant reductions were noted in measures of working heart rate together with significant improvements in grip strength and trunk strength tested at a velocity of 60°.sec·1 at the post-conditioning assessments. In conclusion, the ten-week work-hardening programme resulted in nominal improvements in all the cardiovascular measures and significant improvements in the subjects' strength performance. However, industrialists must recognise that this study dealt with only one aspect of reducing the ergonomic stress index at the workplace and realise that, in addition to this focus, it remains essential to design the task to fit the human operator.
- Full Text:
- Date Issued: 1997
- Authors: Jacka, Karen-Louise
- Date: 1997
- Subjects: Human engineering , Industrial accidents -- South Africa , Industrial safety -- South Africa , Musculoskeletal system -- Wounds and injuries
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:5165 , http://hdl.handle.net/10962/d1016237
- Description: South Africa is a labour-intensive industrially developing country. As a result, in excess of 200 000 workers suffer from musculoskeletal injuries in a year. Research is thus essential to develop more effective strategies in the reduction and rehabilitation of occupational musculoskeletal disorders within industry. It was the hypothesis of this study that by improving the physical work capacity of manual labourers, through participation in an occupation specific work-hardening programme, that the ergonomic stress index and therefore the occurrence of musculoskeletal injuries within industry, may be reduced. Twenty-five male Black and Coloured manual labourers volunteered to participate in this study. In addition to in situ task analyses, the subjects participated in cardiovascular and strength assessments in the laboratory, both pre- and post-participation in the ten-week work-hardening programme. The data were statistically analyzed in order to identify any significant • improvements in the workers' physical work capacity, as measured by cardiovascular, strength and perceptual responses, following the period of work-hardening. Two significant reductions were noted in measures of working heart rate together with significant improvements in grip strength and trunk strength tested at a velocity of 60°.sec·1 at the post-conditioning assessments. In conclusion, the ten-week work-hardening programme resulted in nominal improvements in all the cardiovascular measures and significant improvements in the subjects' strength performance. However, industrialists must recognise that this study dealt with only one aspect of reducing the ergonomic stress index at the workplace and realise that, in addition to this focus, it remains essential to design the task to fit the human operator.
- Full Text:
- Date Issued: 1997
Cytogenetic studies of Pseudobarbus and selected Barbus (Pisces: Cyprinidae) of southern Africa
- Authors: Naran, Daksha
- Date: 1997
- Subjects: Cyprinidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5252 , http://hdl.handle.net/10962/d1005095 , Cyprinidae
- Description: The aim of this study was to explore the karyology of temperate southern African barbine species in order to determine the extent and significance of polyploidy within the species. The study presents an optimised in vivo karyological protocol for the small barbines. The analysis of chromosomal data was explored using two approaches; measured (quantitative) and visual (qualitative). The karyology of 16 species of Barbus and six species of Pseudobarbus (Pisces: Cyprinidae) is reported. The study represents an almost complete (22/23 species) karyological survey of the temperate barbines. Chromosome number, arm numbers (NF) are recorded and karyotype morphology described for all species. Nucleolar organiser regions (NOR)s of 18 species have been examined by silver staining. Seven different AgNOR phenotypes occur among the species examined. Chromosome complements of the different species indicate at least three ploidy levels; diploid, tetraploid and hexaploid. Higher ploidy levels are represented in 78% (18/23) of species within the temperate fauna. This finding is remarkable, in the light of global proportions of cyprinid karyotypes, and provides an opportunity to shed further light on the evolution of polyploidy in barbine cyprinids. Results show that morphologically defined species complexes have distinct karyotypes, and most probably form cohesive phyletic clades. A phylogenetic tree was constructed using traditional morphological characters and tested against karyological data. The results suggests that similar ploidy states do not necessarily indicate close relationship between species. This supports a hypothesis of polyphyly for the African barbine cyprinids and also provides independent support for species complexes such as the "chubbyhead barb group" and the Pseudobarbus lineage. The broader implications of karyological findings are discussed within the context of African barbines and recommendations for further cytogenetic research are provided.
- Full Text:
- Date Issued: 1997
- Authors: Naran, Daksha
- Date: 1997
- Subjects: Cyprinidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5252 , http://hdl.handle.net/10962/d1005095 , Cyprinidae
- Description: The aim of this study was to explore the karyology of temperate southern African barbine species in order to determine the extent and significance of polyploidy within the species. The study presents an optimised in vivo karyological protocol for the small barbines. The analysis of chromosomal data was explored using two approaches; measured (quantitative) and visual (qualitative). The karyology of 16 species of Barbus and six species of Pseudobarbus (Pisces: Cyprinidae) is reported. The study represents an almost complete (22/23 species) karyological survey of the temperate barbines. Chromosome number, arm numbers (NF) are recorded and karyotype morphology described for all species. Nucleolar organiser regions (NOR)s of 18 species have been examined by silver staining. Seven different AgNOR phenotypes occur among the species examined. Chromosome complements of the different species indicate at least three ploidy levels; diploid, tetraploid and hexaploid. Higher ploidy levels are represented in 78% (18/23) of species within the temperate fauna. This finding is remarkable, in the light of global proportions of cyprinid karyotypes, and provides an opportunity to shed further light on the evolution of polyploidy in barbine cyprinids. Results show that morphologically defined species complexes have distinct karyotypes, and most probably form cohesive phyletic clades. A phylogenetic tree was constructed using traditional morphological characters and tested against karyological data. The results suggests that similar ploidy states do not necessarily indicate close relationship between species. This supports a hypothesis of polyphyly for the African barbine cyprinids and also provides independent support for species complexes such as the "chubbyhead barb group" and the Pseudobarbus lineage. The broader implications of karyological findings are discussed within the context of African barbines and recommendations for further cytogenetic research are provided.
- Full Text:
- Date Issued: 1997
An investigation into the effects of inorganic toxins and tryptophan metabolites on the forebrain cholinergic system and the pineal gland of the rat
- Authors: Mahabeer, Rajeshree
- Date: 1997
- Subjects: Toxins -- Physiological effect , Metabolites -- Physiological effect , Pineal gland , Brain -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4018 , http://hdl.handle.net/10962/d1004078 , Toxins -- Physiological effect , Metabolites -- Physiological effect , Pineal gland , Brain -- Physiological aspects
- Description: As soon as the building of the body is completed, the ageing process begins. In the natural course of events, the functioning of some organ systems finally ebbs below the threshold necessary to maintain the body, resulting in death. This occurrence is relatively rare, because diseases superimpose themselves upon the ageing process, bringing premature death resulting from pathological causes. This study focused on the cholinergic system of the rat forebrain. The cholinergic neurons in the brain are said to be involved in memory and learning, and a decrease in the activity of its enzymes has been reported in certain diseases, such as Alzheimer's disease. In the present study, the in vitro effects on the cholinergic system, of aluminium and mercury and tryptophan metabolites, kynurenic acid and quinolinic acid, are determined. Aluminium has been considered as a possible factor in Alzheimer's disease. Mercury in high concentrations is toxic, and its use in amalgam for dental treatment is under consideration with regard to its possible role in promoting neurological disease. The tryptophan metabolites increase in the brain with age and may have a role in pathological diseases. Quinolinic acid, when administered in toxic concentrations produces a possible model for Huntington's disease. This study investigated the effects of the above mentioned toxins on: (1) The synthesis of acetylcholine by choline acetyltransferase; (2) The specific binding of acetylcholine muscarinic receptors; (3) The degradation of acetylcholine by acetyl cholinesterase, Choline acetyltransferase activity did not change in the presence of aluminium chloride, kynurenic acid and quinolinic acid from 1 nM to 1 mM. Mercuric chloride had no significant effect on the enzymes activity from a concentration of 1 nM- 1 pM. At 10 pM there was a significant decrease in cholineacetyltransferase activity (P < 0.001). Enzyme activity continued to decrease at 100 pM (P < 0.0002). At 1 mM, enzyme activity was virtually non existent (P < 0.0001). Acetyl cholinesterase activity was not affected by aluminium chloride, kynurenic acid and quinolinic acid. Mercuric chloride from 1 pM - 1 mM significantly reduced the enzyme activity (P < 0.05). The binding of the antagonist, [³H] quinuclidinyl benzilate (QNB), to acetylcholine muscarinic receptors, revealed that aluminium chloride did not affect the binding of the antagonist, in the concentration range of 1 nM - 100 pM, to the receptors. At 1 mM, aluminium chloride appears to increase the sensitivity of the receptors for the ligand (P < 0.01). Mercuric chloride also does not appear to have any significant effect on receptor binding in this range. However, at 1 mM there appears to be a very significant decrease in receptor binding (P < 0.01). This decrease may be attributed to the interaction of mercury with the sulfhydryl groups in muscarinic receptors. Kynurenic acid had no effect on the receptor binding. Quinolinic acid, in the concentration range from 10 nM - 1 mM increased the binding ofthe receptor to [3Hi QNB significantly (P < 0.001). The study also investigated the effect of the tryptophan metabolites of the kynurenine pathway on pineal indole metabolism. The kynurenine pathway is a major route of tryptophan metabolism in the pineal gland, along with indole metabolism. Investigations showed that kynurenic acid produced a decrease in N-acetylserotonin concentrations ( P < 0.001) and melatonin concentrations (P < 0.003). Further experiments using quinolinic acid produced a similar decrease in N-acetylserotonin (P < 0.001) and melatonin (P < 0.015). A decrease was also noted in the level of 5-methoxytryptophol (P < 0.0005). These findings suggest that aluminium chloride, kynurenic acid and quinolinic acid have no possible role in the decrease of activity of cholinergic enzymes which is observered in diseases such as Alzheimer's disease. The results regarding the effect of mercury chloride on the cholinergic system suggest that low exposure to the toxin will not adversely effect the enzymes. The decrease in N-acetylserotonin and melatonin concentrations reported here, may be a result of kynurenic acid and quinolinic acid having an inhibitory effect on the enzyme, serotonin Nacetyltransferase, which is responsible for the conversion of serotonin to N-acety/serotonin.
- Full Text:
- Date Issued: 1997
- Authors: Mahabeer, Rajeshree
- Date: 1997
- Subjects: Toxins -- Physiological effect , Metabolites -- Physiological effect , Pineal gland , Brain -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4018 , http://hdl.handle.net/10962/d1004078 , Toxins -- Physiological effect , Metabolites -- Physiological effect , Pineal gland , Brain -- Physiological aspects
- Description: As soon as the building of the body is completed, the ageing process begins. In the natural course of events, the functioning of some organ systems finally ebbs below the threshold necessary to maintain the body, resulting in death. This occurrence is relatively rare, because diseases superimpose themselves upon the ageing process, bringing premature death resulting from pathological causes. This study focused on the cholinergic system of the rat forebrain. The cholinergic neurons in the brain are said to be involved in memory and learning, and a decrease in the activity of its enzymes has been reported in certain diseases, such as Alzheimer's disease. In the present study, the in vitro effects on the cholinergic system, of aluminium and mercury and tryptophan metabolites, kynurenic acid and quinolinic acid, are determined. Aluminium has been considered as a possible factor in Alzheimer's disease. Mercury in high concentrations is toxic, and its use in amalgam for dental treatment is under consideration with regard to its possible role in promoting neurological disease. The tryptophan metabolites increase in the brain with age and may have a role in pathological diseases. Quinolinic acid, when administered in toxic concentrations produces a possible model for Huntington's disease. This study investigated the effects of the above mentioned toxins on: (1) The synthesis of acetylcholine by choline acetyltransferase; (2) The specific binding of acetylcholine muscarinic receptors; (3) The degradation of acetylcholine by acetyl cholinesterase, Choline acetyltransferase activity did not change in the presence of aluminium chloride, kynurenic acid and quinolinic acid from 1 nM to 1 mM. Mercuric chloride had no significant effect on the enzymes activity from a concentration of 1 nM- 1 pM. At 10 pM there was a significant decrease in cholineacetyltransferase activity (P < 0.001). Enzyme activity continued to decrease at 100 pM (P < 0.0002). At 1 mM, enzyme activity was virtually non existent (P < 0.0001). Acetyl cholinesterase activity was not affected by aluminium chloride, kynurenic acid and quinolinic acid. Mercuric chloride from 1 pM - 1 mM significantly reduced the enzyme activity (P < 0.05). The binding of the antagonist, [³H] quinuclidinyl benzilate (QNB), to acetylcholine muscarinic receptors, revealed that aluminium chloride did not affect the binding of the antagonist, in the concentration range of 1 nM - 100 pM, to the receptors. At 1 mM, aluminium chloride appears to increase the sensitivity of the receptors for the ligand (P < 0.01). Mercuric chloride also does not appear to have any significant effect on receptor binding in this range. However, at 1 mM there appears to be a very significant decrease in receptor binding (P < 0.01). This decrease may be attributed to the interaction of mercury with the sulfhydryl groups in muscarinic receptors. Kynurenic acid had no effect on the receptor binding. Quinolinic acid, in the concentration range from 10 nM - 1 mM increased the binding ofthe receptor to [3Hi QNB significantly (P < 0.001). The study also investigated the effect of the tryptophan metabolites of the kynurenine pathway on pineal indole metabolism. The kynurenine pathway is a major route of tryptophan metabolism in the pineal gland, along with indole metabolism. Investigations showed that kynurenic acid produced a decrease in N-acetylserotonin concentrations ( P < 0.001) and melatonin concentrations (P < 0.003). Further experiments using quinolinic acid produced a similar decrease in N-acetylserotonin (P < 0.001) and melatonin (P < 0.015). A decrease was also noted in the level of 5-methoxytryptophol (P < 0.0005). These findings suggest that aluminium chloride, kynurenic acid and quinolinic acid have no possible role in the decrease of activity of cholinergic enzymes which is observered in diseases such as Alzheimer's disease. The results regarding the effect of mercury chloride on the cholinergic system suggest that low exposure to the toxin will not adversely effect the enzymes. The decrease in N-acetylserotonin and melatonin concentrations reported here, may be a result of kynurenic acid and quinolinic acid having an inhibitory effect on the enzyme, serotonin Nacetyltransferase, which is responsible for the conversion of serotonin to N-acety/serotonin.
- Full Text:
- Date Issued: 1997
Periglacial features in the vicinity of Tiffindell Ski Resort, North East Cape Drakensberg, South Africa, and their implications for the development of the resort
- Authors: Kück, Karen Melody
- Date: 1997
- Subjects: Tiffindell Ski Resort (South Africa) , Slopes (Physical geography) -- South Africa -- Eastern Cape , Landforms -- South Africa -- Eastern Cape , Climatic geomorphology -- South Africa -- Eastern Cape , Drakensberg Mountains
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4844 , http://hdl.handle.net/10962/d1005520 , Tiffindell Ski Resort (South Africa) , Slopes (Physical geography) -- South Africa -- Eastern Cape , Landforms -- South Africa -- Eastern Cape , Climatic geomorphology -- South Africa -- Eastern Cape , Drakensberg Mountains
- Description: This thesis provides a description of the periglacial environment and features in the vicinity of Tiffindell Ski resort, on the slopes of Ben MacDhui (3001.2m.), the highest point of the East Cape Drakensberg, South Africa. Active and inactive periglacial features were located, mapped and described. Of particular interest were periglaciar slope deposits including gelifluction turf-banked lobes and stone lobes, and cryoturbation features including polygons and thufur. Local environmental factors, such as aspect, moisture, topography, soil texture and depth of freezing, appear to act as important controls on the spatial distribution of the periglacial features. Identification and quantification of periglacial processes in the regolith was investigated using temperature and soil moisture sensors coupled to dataloggers. Research was undertaken over a 16 month period from June 1995 to September 1996 so that comparisons between the winter conditions of 1995 and 1996 could be drawn. The Tiffindell area was observed to be characterised in the winter months by 'diurnal freezethaw days', as well as by 'ice days', 1996 experiencing colder temperatures than 1995. With more than 78% of the days from May to September 1996 being 'ice days', and simultaneously experiencing high soil moisture contents, freezing penetration to a depth of greater than 0.2m was observed to occur in the Tiffindell area, causing frost heave and gelifluction. The summer thaw of ice lenses that developed in the cold winter months caused surface movement downslope of gelifluction lobes of up to 39mm over an 18 month period, although movement declined rapidly with depth and was essentially restricted to the uppermost 130mm of the regolith. Other features such as sorted and non-sorted polygons and thufur were identified and found to be active under the present climatic conditions and depth of frost penetration at Tiffindell. Stone lobes were identified on the south and southeast-facing slopes at Tiffindell, but are apparently inactive under present climatic conditions. Their existence suggests the presence of severe seasonal frost in the past. The implications of the air and ground surface temperatures, and of seasonal frost penetration for the development of Tiffindell Ski resort were considered, and suggestions regarding their economic significance are presented.
- Full Text:
- Date Issued: 1997
- Authors: Kück, Karen Melody
- Date: 1997
- Subjects: Tiffindell Ski Resort (South Africa) , Slopes (Physical geography) -- South Africa -- Eastern Cape , Landforms -- South Africa -- Eastern Cape , Climatic geomorphology -- South Africa -- Eastern Cape , Drakensberg Mountains
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4844 , http://hdl.handle.net/10962/d1005520 , Tiffindell Ski Resort (South Africa) , Slopes (Physical geography) -- South Africa -- Eastern Cape , Landforms -- South Africa -- Eastern Cape , Climatic geomorphology -- South Africa -- Eastern Cape , Drakensberg Mountains
- Description: This thesis provides a description of the periglacial environment and features in the vicinity of Tiffindell Ski resort, on the slopes of Ben MacDhui (3001.2m.), the highest point of the East Cape Drakensberg, South Africa. Active and inactive periglacial features were located, mapped and described. Of particular interest were periglaciar slope deposits including gelifluction turf-banked lobes and stone lobes, and cryoturbation features including polygons and thufur. Local environmental factors, such as aspect, moisture, topography, soil texture and depth of freezing, appear to act as important controls on the spatial distribution of the periglacial features. Identification and quantification of periglacial processes in the regolith was investigated using temperature and soil moisture sensors coupled to dataloggers. Research was undertaken over a 16 month period from June 1995 to September 1996 so that comparisons between the winter conditions of 1995 and 1996 could be drawn. The Tiffindell area was observed to be characterised in the winter months by 'diurnal freezethaw days', as well as by 'ice days', 1996 experiencing colder temperatures than 1995. With more than 78% of the days from May to September 1996 being 'ice days', and simultaneously experiencing high soil moisture contents, freezing penetration to a depth of greater than 0.2m was observed to occur in the Tiffindell area, causing frost heave and gelifluction. The summer thaw of ice lenses that developed in the cold winter months caused surface movement downslope of gelifluction lobes of up to 39mm over an 18 month period, although movement declined rapidly with depth and was essentially restricted to the uppermost 130mm of the regolith. Other features such as sorted and non-sorted polygons and thufur were identified and found to be active under the present climatic conditions and depth of frost penetration at Tiffindell. Stone lobes were identified on the south and southeast-facing slopes at Tiffindell, but are apparently inactive under present climatic conditions. Their existence suggests the presence of severe seasonal frost in the past. The implications of the air and ground surface temperatures, and of seasonal frost penetration for the development of Tiffindell Ski resort were considered, and suggestions regarding their economic significance are presented.
- Full Text:
- Date Issued: 1997
Knowledge of safe sex practices and HIV transmission, propensity for risk taking, and alcohol/drug use in the aetiology of unprotected sex
- Authors: Simpson, Malcolm Robert
- Date: 1997
- Subjects: HIV infections -- Prevention , Safe sex in AIDS prevention
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3146 , http://hdl.handle.net/10962/d1007421 , HIV infections -- Prevention , Safe sex in AIDS prevention
- Description: Second year psychology students (N=176) from Rhodes University were surveyed using an anonymous questionnaire to obtain information on sexual behaviour and knowledge of the acquired immunodeficiency syndrome (AIDS) among young people. The following information was obtained: Knowledge of safe sex practices and HIV transmission was high although a number of misconceptions were noted. Only fifty six percent of students viewed oral sex with a condom as safe and thirty one percent do not consider mutual masturbation with a condom safe. Thirteen percent and twenty five percent respectively identified insects and saliva as being routes of HIV transmission. Magazines (96%), informal discussions with friends (95%), public pamphlets (86%) and public television (79%) were preferred sources of information. The students' knowledge did not appear to significantly affect sexual behaviour. Eighty percent of respondents were intimately involved with another person during the past twelve months, and only fifteen percent always made use of a latex barrier when being sexually intimate. Despite high rates of alcohol and/or drug consumption (80% of students use such substances), and the belief by the majority of respondents that alcohol and/or drugs facilitate higher risk behaviours, no support for the alcohol/risky sex hypothesis was found. Students were found to score highly on proneness to psychological and behavioural risk taking, and no significant relationship between this and unprotected sex was found. It can be concluded that educational programmes need to focus on what constitutes safe sexual practices in order to equip young adults with the knowledge they need to make informed choices regarding the relative risks of various sexual activities.
- Full Text:
- Date Issued: 1997
- Authors: Simpson, Malcolm Robert
- Date: 1997
- Subjects: HIV infections -- Prevention , Safe sex in AIDS prevention
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3146 , http://hdl.handle.net/10962/d1007421 , HIV infections -- Prevention , Safe sex in AIDS prevention
- Description: Second year psychology students (N=176) from Rhodes University were surveyed using an anonymous questionnaire to obtain information on sexual behaviour and knowledge of the acquired immunodeficiency syndrome (AIDS) among young people. The following information was obtained: Knowledge of safe sex practices and HIV transmission was high although a number of misconceptions were noted. Only fifty six percent of students viewed oral sex with a condom as safe and thirty one percent do not consider mutual masturbation with a condom safe. Thirteen percent and twenty five percent respectively identified insects and saliva as being routes of HIV transmission. Magazines (96%), informal discussions with friends (95%), public pamphlets (86%) and public television (79%) were preferred sources of information. The students' knowledge did not appear to significantly affect sexual behaviour. Eighty percent of respondents were intimately involved with another person during the past twelve months, and only fifteen percent always made use of a latex barrier when being sexually intimate. Despite high rates of alcohol and/or drug consumption (80% of students use such substances), and the belief by the majority of respondents that alcohol and/or drugs facilitate higher risk behaviours, no support for the alcohol/risky sex hypothesis was found. Students were found to score highly on proneness to psychological and behavioural risk taking, and no significant relationship between this and unprotected sex was found. It can be concluded that educational programmes need to focus on what constitutes safe sexual practices in order to equip young adults with the knowledge they need to make informed choices regarding the relative risks of various sexual activities.
- Full Text:
- Date Issued: 1997
Isolation and identification of Beta-Lactam Producing Microorganisms using PCR based methodologies
- Authors: Krallis, Myrsini
- Date: 1997
- Subjects: Polymerase chain reaction , Bacterial genetics , Fungi -- Genetics , Beta lactam antibiotics , Microbial enzymes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4155 , http://hdl.handle.net/10962/d1018237
- Description: The polymerase chain reaction (PCR) was investigated as a potential tool in microbial screening for 13-lactam. producing organisms. Optimization of PCR conditions and the addition of acetamide to the PCR reaction allowed for the successful amplification of the isopenicillin N synthetase (lPNS) gene in S. clavuligerus, S. tanashiensis, S. griseus, S. olivaceus, S. lipmanii, and S. chartreusis. PCR was used to produce a radiolabelled probe from S. clavuligerus that was used to detect analogous genes in bacteria and fungi. Southern blot and dot blot analysis using the lPNS probe revealed the presence of IPNS-like sequences in seventeen organisms. Fourteen of these sequences belonged to known 13-lactam. producing organisms; one unidentified soil isolate; and two non-/3-lactam. producing organisms viz. S. venezuelae ATCC 10712 and S. hygroscopicus ATCC 21703. The lPNS gene was also detected in a 13-lactam producer (S. chartreusis) that had lost its ability to produce antibiotic. It would therefore have been overlooked in a conventional antibiotic screening program. The use of PCR, coupled with Southern hybridization and dot blot analysis, increased the sensitivity and specificity of the antibiotic screening procedures and allowed for the investigation of evolutionary relationships between the eukaryotes and the prokaryotes. A preliminary investigation into the potential use of RAPD PCR and protein fmgerprinting as tools for solving discrepancies in streptomycete identification was conducted. A variety of streptomycete species that were chosen as being representative of a number of numerical taxonomic classes were amplified using various RAPD primers. Streptomycetes appear to be genetically diverse organisms as was reflected by their RAPD and protein profiles. The application of PCR in an antibiotic screening program showed great potential as a specific and sensitive tool in the detection of /3-lactam producers and in the elimination of duplicate strains.
- Full Text:
- Date Issued: 1997
- Authors: Krallis, Myrsini
- Date: 1997
- Subjects: Polymerase chain reaction , Bacterial genetics , Fungi -- Genetics , Beta lactam antibiotics , Microbial enzymes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4155 , http://hdl.handle.net/10962/d1018237
- Description: The polymerase chain reaction (PCR) was investigated as a potential tool in microbial screening for 13-lactam. producing organisms. Optimization of PCR conditions and the addition of acetamide to the PCR reaction allowed for the successful amplification of the isopenicillin N synthetase (lPNS) gene in S. clavuligerus, S. tanashiensis, S. griseus, S. olivaceus, S. lipmanii, and S. chartreusis. PCR was used to produce a radiolabelled probe from S. clavuligerus that was used to detect analogous genes in bacteria and fungi. Southern blot and dot blot analysis using the lPNS probe revealed the presence of IPNS-like sequences in seventeen organisms. Fourteen of these sequences belonged to known 13-lactam. producing organisms; one unidentified soil isolate; and two non-/3-lactam. producing organisms viz. S. venezuelae ATCC 10712 and S. hygroscopicus ATCC 21703. The lPNS gene was also detected in a 13-lactam producer (S. chartreusis) that had lost its ability to produce antibiotic. It would therefore have been overlooked in a conventional antibiotic screening program. The use of PCR, coupled with Southern hybridization and dot blot analysis, increased the sensitivity and specificity of the antibiotic screening procedures and allowed for the investigation of evolutionary relationships between the eukaryotes and the prokaryotes. A preliminary investigation into the potential use of RAPD PCR and protein fmgerprinting as tools for solving discrepancies in streptomycete identification was conducted. A variety of streptomycete species that were chosen as being representative of a number of numerical taxonomic classes were amplified using various RAPD primers. Streptomycetes appear to be genetically diverse organisms as was reflected by their RAPD and protein profiles. The application of PCR in an antibiotic screening program showed great potential as a specific and sensitive tool in the detection of /3-lactam producers and in the elimination of duplicate strains.
- Full Text:
- Date Issued: 1997
Environmental perceptions and knowledge among political leaders in the Eastern Cape Province and some implications for environmental policy
- Authors: Mbengashe, Pauline Maria
- Date: 1997
- Subjects: Environmental policy -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1517 , http://hdl.handle.net/10962/d1003399
- Description: The environmental and development challenges facing South Africa are closely linked with the political and economic inequalities of the past. The achievement of sustainable. development will require social and political change. Protection and conservation of the environment, improving environmental knowledge and understanding, the participation of all citizens, effective environmental management, inclusive and implementable policies and legislation, are all necessary components of sustainable development. These requirements are in line with the Rio Declaration on Environment and Development and Agenda 21, a programme of action coming out of the United Nations Conference on Environment and Development (UNCED 1992) This study explores the environmental perceptions and knowledge of some representative Eastern Cape political leaders. The aim of the study was to share views on environmental issues, concerns and strategies that might lead to improved environmental understanding, informed policy change and effective environmental management. Different environmental ideologies were also explored because of the political and ideological nature of the concepts 'environment' and 'education'. Data was collected from semi-structured interviews undertaken with ten political leaders in the Eastern Cape Province Legislature. The study revealed a general awareness and understanding of environmental issues with unsupported indepth knowledge and detailed information. The political, development, social and economic dimensions of the environment were emphasised more than the ecological and physical aspects. The need for environmental information, policies and legislation was recognised. Both formal and non-formal environmental education were emphasised. The need to redefine environmental education and make it more relevant, problem solving and action oriented was also emphasised. The challenge is to improve environmental understanding and making environmental information available to political leaders, government officials and citizens in general.
- Full Text:
- Date Issued: 1997
- Authors: Mbengashe, Pauline Maria
- Date: 1997
- Subjects: Environmental policy -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1517 , http://hdl.handle.net/10962/d1003399
- Description: The environmental and development challenges facing South Africa are closely linked with the political and economic inequalities of the past. The achievement of sustainable. development will require social and political change. Protection and conservation of the environment, improving environmental knowledge and understanding, the participation of all citizens, effective environmental management, inclusive and implementable policies and legislation, are all necessary components of sustainable development. These requirements are in line with the Rio Declaration on Environment and Development and Agenda 21, a programme of action coming out of the United Nations Conference on Environment and Development (UNCED 1992) This study explores the environmental perceptions and knowledge of some representative Eastern Cape political leaders. The aim of the study was to share views on environmental issues, concerns and strategies that might lead to improved environmental understanding, informed policy change and effective environmental management. Different environmental ideologies were also explored because of the political and ideological nature of the concepts 'environment' and 'education'. Data was collected from semi-structured interviews undertaken with ten political leaders in the Eastern Cape Province Legislature. The study revealed a general awareness and understanding of environmental issues with unsupported indepth knowledge and detailed information. The political, development, social and economic dimensions of the environment were emphasised more than the ecological and physical aspects. The need for environmental information, policies and legislation was recognised. Both formal and non-formal environmental education were emphasised. The need to redefine environmental education and make it more relevant, problem solving and action oriented was also emphasised. The challenge is to improve environmental understanding and making environmental information available to political leaders, government officials and citizens in general.
- Full Text:
- Date Issued: 1997
Exploitation of the bait organism Upogebia africana (Crustacea: Anomura) in the Knysna estuary
- Authors: Cretchley, Robyn
- Date: 1997
- Subjects: Upogebia africana -- South Africa -- Knysna , Mud shrimps -- South Africa -- Knysna , Fishing baits -- South Africa -- Knysna
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5691 , http://hdl.handle.net/10962/d1005377 , Upogebia africana -- South Africa -- Knysna , Mud shrimps -- South Africa -- Knysna , Fishing baits -- South Africa -- Knysna
- Description: In South African estuaries the anomuran mud prawn, Upogebia africana (Ortmann), is the main organism exploited as bait by recreational and subsistence anglers. In the Knysna estuary, three groups of bait collectors were identified on the basis of their source of income: subsistence fishermen who rely on bait-collecting and fishing for their income, supplementary anglers who catch fish to supplement their income and leisure anglers who draw no income from fishing. Two groups were identified based on the methods used: lelsure anglers who collect bait using a prawn pusher or pump and fish using a fishing rod and tackle, and non-leisure anglers who collect mud prawns using tin cans and fish with handlines. The hypothesis was erected that bait-collecting does not affect the U africana populations in the Knysna estuary. The approach adopted was to assess the distribution, density, population structure and reproductive patterns of the bait stock and to estimate the intensity of bait collection, to test the validity of the hypothesis. U africana has an extensive distribution, occupying 62 % of the available intertidal area of the Knysna estuary. Mud prawns have a broad intertidal distribution from the high water level (Spartina zone) to the shallow subtidal. The density, biomass and population structure of the mud prawns vary significantly with distance up the estuary and with tidal height on each shore. The Invertebrate Reserve supports very low densities of U africana (x = 11.7 m⁻²), whereas a relatively inaccessible centre bank in the middle reaches of the estuary appears to be a very effective natural mud prawn reserve as it supports the highest densities (x = 176.5m⁻²). The mud prawn stock of the estuary is estimated to be 2.19 x 108 prawns (82.7 tonnes dry mass). The numbers of bait collectors present per mudbank is highest on public holidays (x = 34) and higher during the summer holidays (x = 16) than during the winter (x = 4). A total of 1.858 x 106 U africana or 700.53 kg (dry mass) are removed by bait collectors annually from the 6 popular bait-collecting sites studied. This represents 8.49 % of the mud prawn stocks at these sites and 0.85 % of the entire estuary stock. 85 % of the U africana taken as bait annually, is removed by the 77.12 % of bait collectors who are non-leisure anglers. Recreational or leisure anglers are responsible for removing 14.2 %. The reproduction of female U africana in the Knysna estuary is seasonal and occurs from late July to April. There is evidence that this breeding season consists of two merging breeding cycles. The largest percentage (63 %) of ovigerous females is found in the middle reaches of the Knysna estuary at the Oyster Bank where the highest numbers of stage 1 larvae (165 m⁻³) are released. Larvae were exported from the estuary on the crepuscular ebb tide with peaks in abundance of nearly 1500 m⁻³ in November 1995 and January 1996. Although numbers caught are not significantly higher, larvae are nearly twice as abundant on crepuscular neap tides following a new moon (waxing quarter) than on those following a full moon (waning quarter). Recruitment of juvenile U africana to populations in the estuary was highest in December (45 m⁻²) and decreased over the summer. The highest numbers of recruits (31 m⁻²) were found at those sites closest to the mouth or on the main channel. Recruitment to the Leisure Isle and Thesens sites which are intensively exploited by bait collectors is high (20 - 32 m⁻²). The number of juveniles recruiting to U africana populations is estimated to be four times as high as the numbers of mud prawns taken by bait collectors. Legal methods of bait collection used in the Knysna estuary by the majority of anglers appear to cause minimal sediment disturbance and are not likely to affect the associated infauna. Illegal bait-collecting methods are however highly destructive and must be prohibited. It is concluded that the null hypothesis is acceptable, as mud prawn stocks of the Knysna estuary are not over-exploited and appear to be naturally regulated. The recruitment rate of juvenile U africana is estimated to be sufficiently high to sustain the present levels of exploitation.
- Full Text:
- Date Issued: 1997
- Authors: Cretchley, Robyn
- Date: 1997
- Subjects: Upogebia africana -- South Africa -- Knysna , Mud shrimps -- South Africa -- Knysna , Fishing baits -- South Africa -- Knysna
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5691 , http://hdl.handle.net/10962/d1005377 , Upogebia africana -- South Africa -- Knysna , Mud shrimps -- South Africa -- Knysna , Fishing baits -- South Africa -- Knysna
- Description: In South African estuaries the anomuran mud prawn, Upogebia africana (Ortmann), is the main organism exploited as bait by recreational and subsistence anglers. In the Knysna estuary, three groups of bait collectors were identified on the basis of their source of income: subsistence fishermen who rely on bait-collecting and fishing for their income, supplementary anglers who catch fish to supplement their income and leisure anglers who draw no income from fishing. Two groups were identified based on the methods used: lelsure anglers who collect bait using a prawn pusher or pump and fish using a fishing rod and tackle, and non-leisure anglers who collect mud prawns using tin cans and fish with handlines. The hypothesis was erected that bait-collecting does not affect the U africana populations in the Knysna estuary. The approach adopted was to assess the distribution, density, population structure and reproductive patterns of the bait stock and to estimate the intensity of bait collection, to test the validity of the hypothesis. U africana has an extensive distribution, occupying 62 % of the available intertidal area of the Knysna estuary. Mud prawns have a broad intertidal distribution from the high water level (Spartina zone) to the shallow subtidal. The density, biomass and population structure of the mud prawns vary significantly with distance up the estuary and with tidal height on each shore. The Invertebrate Reserve supports very low densities of U africana (x = 11.7 m⁻²), whereas a relatively inaccessible centre bank in the middle reaches of the estuary appears to be a very effective natural mud prawn reserve as it supports the highest densities (x = 176.5m⁻²). The mud prawn stock of the estuary is estimated to be 2.19 x 108 prawns (82.7 tonnes dry mass). The numbers of bait collectors present per mudbank is highest on public holidays (x = 34) and higher during the summer holidays (x = 16) than during the winter (x = 4). A total of 1.858 x 106 U africana or 700.53 kg (dry mass) are removed by bait collectors annually from the 6 popular bait-collecting sites studied. This represents 8.49 % of the mud prawn stocks at these sites and 0.85 % of the entire estuary stock. 85 % of the U africana taken as bait annually, is removed by the 77.12 % of bait collectors who are non-leisure anglers. Recreational or leisure anglers are responsible for removing 14.2 %. The reproduction of female U africana in the Knysna estuary is seasonal and occurs from late July to April. There is evidence that this breeding season consists of two merging breeding cycles. The largest percentage (63 %) of ovigerous females is found in the middle reaches of the Knysna estuary at the Oyster Bank where the highest numbers of stage 1 larvae (165 m⁻³) are released. Larvae were exported from the estuary on the crepuscular ebb tide with peaks in abundance of nearly 1500 m⁻³ in November 1995 and January 1996. Although numbers caught are not significantly higher, larvae are nearly twice as abundant on crepuscular neap tides following a new moon (waxing quarter) than on those following a full moon (waning quarter). Recruitment of juvenile U africana to populations in the estuary was highest in December (45 m⁻²) and decreased over the summer. The highest numbers of recruits (31 m⁻²) were found at those sites closest to the mouth or on the main channel. Recruitment to the Leisure Isle and Thesens sites which are intensively exploited by bait collectors is high (20 - 32 m⁻²). The number of juveniles recruiting to U africana populations is estimated to be four times as high as the numbers of mud prawns taken by bait collectors. Legal methods of bait collection used in the Knysna estuary by the majority of anglers appear to cause minimal sediment disturbance and are not likely to affect the associated infauna. Illegal bait-collecting methods are however highly destructive and must be prohibited. It is concluded that the null hypothesis is acceptable, as mud prawn stocks of the Knysna estuary are not over-exploited and appear to be naturally regulated. The recruitment rate of juvenile U africana is estimated to be sufficiently high to sustain the present levels of exploitation.
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- Date Issued: 1997