Field guide to the Quaternary glacial, periglacial and colluvial features of the East Cape Drakensberg
- Authors: Lewis, Colin A
- Date: 1994
- Language: English
- Type: Book
- Identifier: vital:6704 , http://hdl.handle.net/10962/d1006740 , ISBN 0-86810-271-7
- Description: Most of the sites described in this publication are located on privately-owned farmland. Permission to visit sites should be obtained from the relevant landowner. This Field Guide was produced for a Field Meeting of the Southern African Society for Quaternary Research, held in May 1994 and based at Rhodes, led by Colin A, Lewis, (Rhodes University), Evan S,J, Dollar (University of Transkei), Trevor Hill (Rhodes University). It was published on behalf of the Southern African Society for Quaternary Research by the Dept. of Geography, Rhodes University.
- Full Text: false
- Date Issued: 1994
- Authors: Lewis, Colin A
- Date: 1994
- Language: English
- Type: Book
- Identifier: vital:6704 , http://hdl.handle.net/10962/d1006740 , ISBN 0-86810-271-7
- Description: Most of the sites described in this publication are located on privately-owned farmland. Permission to visit sites should be obtained from the relevant landowner. This Field Guide was produced for a Field Meeting of the Southern African Society for Quaternary Research, held in May 1994 and based at Rhodes, led by Colin A, Lewis, (Rhodes University), Evan S,J, Dollar (University of Transkei), Trevor Hill (Rhodes University). It was published on behalf of the Southern African Society for Quaternary Research by the Dept. of Geography, Rhodes University.
- Full Text: false
- Date Issued: 1994
Farmers' strategies and their implications for land reform in the Orange Free State
- Authors: Beinart, William
- Date: 1994
- Subjects: Agriculture -- Orange Free State Land reform -- South Africa -- Orange Free State Land tenure -- Orange Free State
- Language: English
- Type: text , Manuscript
- Identifier: http://hdl.handle.net/10962/2813 , vital:20328
- Description: It is possible to conjure a wide variety of future agricultural scenarios in South Africa. But new policies should be developed only with close attention to what exists and what is feasible. Analysis of the potential for land reform should remain sensitive to local ecological and economic conditions and to the current strategies of both farmers and dispossessed. Rural life for many people remains insecure. Farmworkers are particularly vulnerable at present and might become more so in a phase of rapid reform and uncertainty. Although the most carefully planned strategy of reform might be undermined by the sheer demand for land or informal reoccupations, the aims of restitution, justice and redistribution should be tempered by the equally difficult demands of production. Drawing on material from a local research project in the Orange Free State (OFS), done jointly with Colin Murray, this article concentrates on three issues: patterns of land ownership; farming strategies; and land availability. The position of farmworkers and those who have recently moved off farms, as well as the potential for new patterns of occupation will be addressed in subsequent project papers (Murray, 1993). , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1994
- Authors: Beinart, William
- Date: 1994
- Subjects: Agriculture -- Orange Free State Land reform -- South Africa -- Orange Free State Land tenure -- Orange Free State
- Language: English
- Type: text , Manuscript
- Identifier: http://hdl.handle.net/10962/2813 , vital:20328
- Description: It is possible to conjure a wide variety of future agricultural scenarios in South Africa. But new policies should be developed only with close attention to what exists and what is feasible. Analysis of the potential for land reform should remain sensitive to local ecological and economic conditions and to the current strategies of both farmers and dispossessed. Rural life for many people remains insecure. Farmworkers are particularly vulnerable at present and might become more so in a phase of rapid reform and uncertainty. Although the most carefully planned strategy of reform might be undermined by the sheer demand for land or informal reoccupations, the aims of restitution, justice and redistribution should be tempered by the equally difficult demands of production. Drawing on material from a local research project in the Orange Free State (OFS), done jointly with Colin Murray, this article concentrates on three issues: patterns of land ownership; farming strategies; and land availability. The position of farmworkers and those who have recently moved off farms, as well as the potential for new patterns of occupation will be addressed in subsequent project papers (Murray, 1993). , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1994
Effects of an enriched physical activity programme on selected anthropometric, physiological and performance characteristics of an underprivilieged ethnic group
- Authors: Van Rooyen, Frederick
- Date: 1994
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:21115 , http://hdl.handle.net/10962/6455
- Description: Fifty pre-pubescent Xhosa-speaking children from two primary schools within the township of Rini, Grahamstown, were selected in this study to determine the effects, if any, of an enriched physical activity programme. Subjects were divided into experimental and control groups with only the experimental group physically participating in the enrichment programme. Selected anthropometric, physiological and motor performance tests were administered on both groups, before and after the programme, to monitor the effect of the enrichment programme on growth, cardiovascular efficiency and physical performance. Somatotype ratings showed no change after the training programme. However body composition showed greater gains in fat mass in the control group and marked drops in fat mass and increases in lean body mass in the experimental group. Longer running distances, higher predicted VO2 max mean values and improved recovery heart rate (HR) as well as larger gains in relative power, absolute power and velocity were experienced by individuals who participated in the training programme. The performance of the experimental group in the two motor performance tests out-weighed by far the performance of the control group as a result of the additional programme. The enrichment programme not only produced a positive effect on body composition but also improved aerobic and anaerobic efficiency. Improvements in both motor performance tests favoured the experimental group.
- Full Text:
- Date Issued: 1994
- Authors: Van Rooyen, Frederick
- Date: 1994
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:21115 , http://hdl.handle.net/10962/6455
- Description: Fifty pre-pubescent Xhosa-speaking children from two primary schools within the township of Rini, Grahamstown, were selected in this study to determine the effects, if any, of an enriched physical activity programme. Subjects were divided into experimental and control groups with only the experimental group physically participating in the enrichment programme. Selected anthropometric, physiological and motor performance tests were administered on both groups, before and after the programme, to monitor the effect of the enrichment programme on growth, cardiovascular efficiency and physical performance. Somatotype ratings showed no change after the training programme. However body composition showed greater gains in fat mass in the control group and marked drops in fat mass and increases in lean body mass in the experimental group. Longer running distances, higher predicted VO2 max mean values and improved recovery heart rate (HR) as well as larger gains in relative power, absolute power and velocity were experienced by individuals who participated in the training programme. The performance of the experimental group in the two motor performance tests out-weighed by far the performance of the control group as a result of the additional programme. The enrichment programme not only produced a positive effect on body composition but also improved aerobic and anaerobic efficiency. Improvements in both motor performance tests favoured the experimental group.
- Full Text:
- Date Issued: 1994
Editorial
- Janse van Rensburg, Eureta, Irwin, Patrick R
- Authors: Janse van Rensburg, Eureta , Irwin, Patrick R
- Date: 1994
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438694 , vital:73491 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137493"
- Description: In 1993 environmental education was looking forward to the first democratic election in South Africa - now it is in the midst of 'reconstructionand-development'. For many local environmental educators, this means a contrihution, in one way or another, to the new national curriculum. But the challenges of 1993 continue: processes of participative curriculum development are forcing us to clarify different orientations to environmental education in our efforts to shape a curriculum based on the best of our various visions.
- Full Text:
- Date Issued: 1994
- Authors: Janse van Rensburg, Eureta , Irwin, Patrick R
- Date: 1994
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/438694 , vital:73491 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/137493"
- Description: In 1993 environmental education was looking forward to the first democratic election in South Africa - now it is in the midst of 'reconstructionand-development'. For many local environmental educators, this means a contrihution, in one way or another, to the new national curriculum. But the challenges of 1993 continue: processes of participative curriculum development are forcing us to clarify different orientations to environmental education in our efforts to shape a curriculum based on the best of our various visions.
- Full Text:
- Date Issued: 1994
Ecology of the ichthyofauna in three temporarily open/closed estuaries on the Natal coast
- Authors: Harrison, Trevor D
- Date: 1994
- Subjects: Estuarine ecology -- South Africa -- KwaZulu-Natal , Estuarine animals -- South Africa -- Swartkops River Estuary , Fishes -- South Africa -- KwaZulu-Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5269 , http://hdl.handle.net/10962/d1005113 , Estuarine ecology -- South Africa -- KwaZulu-Natal , Estuarine animals -- South Africa -- Swartkops River Estuary , Fishes -- South Africa -- KwaZulu-Natal
- Description: The ichthyofauna of three small Natal estuaries, the Mhlanga, Damba and Zotsha was sampled over a period of two years. A total of 68 kinds of fishes representing 24 families, 39 genera and 56 species were captured during this study. Forty seven kinds of fishes were recorded in the Mhlanga of which Gilchristella aestuaria,Oreochromis mossambicus, Valamugil cunnesius, Valamugil sp. and juvenile mugilids numerically dominated. In terms of biomass, O. mossambicus, V. cunnesius, Liza alata, Myxus capensis and Mugil cephalus dominated the ichthyofauna of the Mhlanga. In the Damba, 24 kinds of fishes were recorded. The most abundant fishes captured were Glossogobius callidus, M. capensis and O. mossambicus. M. capensis, M. cephalus, O. mossambicus and G. callidus dominated the fish biomass captured in the Damba. A total of 56 kinds of fishes were recorded in the Zotsha during this study. The ichthyofauna of the Zotsha was numerically dominated by juvenile mugilids, G. aestuaria, O. mossambicus, Rhabdosargus holubi, Terapon jarbua, Ambassis productus and G. callidus. The species which dominated the fish biomass in the Zotsha were O. mossambicus, L. alata, Valamugil robustus, Valamugil buchanani, M. capensis, M. cephalus and V. cunnesius. Classifying the species captured according to whether they were resident estuarine species, freshwater species, estuarine-dependent marine species and marine species revealed that the first three groups were all well represented in the systems. The only system in which marine species made any significant contribution to the ichthyofauna was the Zotsha. Oreochromis mossambicus was the dominant freshwater species in all three estuaries during this study. Gilchristella aestuaria and Glossogobius callidus were the principal estuarine species in the Mhlanga and the Damba respectively. Both G. aestuaria and G. callidus were the dominant estuarine species captured in the Zotsha. The principal estuarine-dependent marine fishes captured in the Mhlanga were V. cunnesius, Valamugil sp., juvenile mugilids, M. capensis, M. cephalus and L. alata. In the Damba, M. capensis and M. cephalus were the dominant estuarine-dependent marine species and in the Zotsha juvenile mugilids, R. holubi, T. jarbua, A . productus, M. capensis, V. cunnesius, V. robustus, M. cephalus and L. alata predominated. The results of this study indicate that the estuaries are dominated at different periods by different assemblages of fishes. This is linked to the spawning and migration patterns of the various species as well as the hydrological regime of each estuary. During the winter these systems are normally closed with relatively deep waters and high food resource and habitat availability. Freshwater and estuarine species mainly inhabit the upper reaches of the systems while estuarine-dependent marine species mainly occupy the middle and lower reaches and dominate the fish community. When these systems open with the onset of the spring/summer rains, adult and sub-adult estuarine-dependent marine species emigrate to the marine environment and juveniles begin recruiting into the systems. Spring is also the peak breeding period of resident estuarine and freshwater species, resulting in an increase in the contribution of these fishes to the overall population during this period. When closed estuaries open many of them drain and this results in the fishes concentrating in the lower reaches of the system where moderate water depths are present, thus further contributing to an increase in the proportion of freshwater and estuarine species in this region. The breaching of closed estuaries also results in a slump in food resources and habitat availability. Competition and possible increased vulnerability to avian predation (due to the shallow nature of the systems), may contribute to a decrease in the proportion of estuarine and freshwater species in summer. The prolonged spawning and recruitment of 0+ juveniles of estuarine-dependent marine species results in an increase in the proportion of these fishes present in the estuaries during summer. In autumn, these systems normally close, water levels rise and available food resources and habitat increase. This allows the redistribution of freshwater and estuarine species upstream, leaving estuarine-dependent marine species to dominate the middle and lower reaches. Although temporarily open/closed estuaries along the Natal coast may not be as diverse as permanently open estuaries in terms of their ichthyofauna, their importance must not be underestimated since by providing a continuous sequence of sheltered habitats along the coast they may contribute significantly to the viability of estuarine-dependent marine fish stocks.
- Full Text:
- Date Issued: 1994
- Authors: Harrison, Trevor D
- Date: 1994
- Subjects: Estuarine ecology -- South Africa -- KwaZulu-Natal , Estuarine animals -- South Africa -- Swartkops River Estuary , Fishes -- South Africa -- KwaZulu-Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5269 , http://hdl.handle.net/10962/d1005113 , Estuarine ecology -- South Africa -- KwaZulu-Natal , Estuarine animals -- South Africa -- Swartkops River Estuary , Fishes -- South Africa -- KwaZulu-Natal
- Description: The ichthyofauna of three small Natal estuaries, the Mhlanga, Damba and Zotsha was sampled over a period of two years. A total of 68 kinds of fishes representing 24 families, 39 genera and 56 species were captured during this study. Forty seven kinds of fishes were recorded in the Mhlanga of which Gilchristella aestuaria,Oreochromis mossambicus, Valamugil cunnesius, Valamugil sp. and juvenile mugilids numerically dominated. In terms of biomass, O. mossambicus, V. cunnesius, Liza alata, Myxus capensis and Mugil cephalus dominated the ichthyofauna of the Mhlanga. In the Damba, 24 kinds of fishes were recorded. The most abundant fishes captured were Glossogobius callidus, M. capensis and O. mossambicus. M. capensis, M. cephalus, O. mossambicus and G. callidus dominated the fish biomass captured in the Damba. A total of 56 kinds of fishes were recorded in the Zotsha during this study. The ichthyofauna of the Zotsha was numerically dominated by juvenile mugilids, G. aestuaria, O. mossambicus, Rhabdosargus holubi, Terapon jarbua, Ambassis productus and G. callidus. The species which dominated the fish biomass in the Zotsha were O. mossambicus, L. alata, Valamugil robustus, Valamugil buchanani, M. capensis, M. cephalus and V. cunnesius. Classifying the species captured according to whether they were resident estuarine species, freshwater species, estuarine-dependent marine species and marine species revealed that the first three groups were all well represented in the systems. The only system in which marine species made any significant contribution to the ichthyofauna was the Zotsha. Oreochromis mossambicus was the dominant freshwater species in all three estuaries during this study. Gilchristella aestuaria and Glossogobius callidus were the principal estuarine species in the Mhlanga and the Damba respectively. Both G. aestuaria and G. callidus were the dominant estuarine species captured in the Zotsha. The principal estuarine-dependent marine fishes captured in the Mhlanga were V. cunnesius, Valamugil sp., juvenile mugilids, M. capensis, M. cephalus and L. alata. In the Damba, M. capensis and M. cephalus were the dominant estuarine-dependent marine species and in the Zotsha juvenile mugilids, R. holubi, T. jarbua, A . productus, M. capensis, V. cunnesius, V. robustus, M. cephalus and L. alata predominated. The results of this study indicate that the estuaries are dominated at different periods by different assemblages of fishes. This is linked to the spawning and migration patterns of the various species as well as the hydrological regime of each estuary. During the winter these systems are normally closed with relatively deep waters and high food resource and habitat availability. Freshwater and estuarine species mainly inhabit the upper reaches of the systems while estuarine-dependent marine species mainly occupy the middle and lower reaches and dominate the fish community. When these systems open with the onset of the spring/summer rains, adult and sub-adult estuarine-dependent marine species emigrate to the marine environment and juveniles begin recruiting into the systems. Spring is also the peak breeding period of resident estuarine and freshwater species, resulting in an increase in the contribution of these fishes to the overall population during this period. When closed estuaries open many of them drain and this results in the fishes concentrating in the lower reaches of the system where moderate water depths are present, thus further contributing to an increase in the proportion of freshwater and estuarine species in this region. The breaching of closed estuaries also results in a slump in food resources and habitat availability. Competition and possible increased vulnerability to avian predation (due to the shallow nature of the systems), may contribute to a decrease in the proportion of estuarine and freshwater species in summer. The prolonged spawning and recruitment of 0+ juveniles of estuarine-dependent marine species results in an increase in the proportion of these fishes present in the estuaries during summer. In autumn, these systems normally close, water levels rise and available food resources and habitat increase. This allows the redistribution of freshwater and estuarine species upstream, leaving estuarine-dependent marine species to dominate the middle and lower reaches. Although temporarily open/closed estuaries along the Natal coast may not be as diverse as permanently open estuaries in terms of their ichthyofauna, their importance must not be underestimated since by providing a continuous sequence of sheltered habitats along the coast they may contribute significantly to the viability of estuarine-dependent marine fish stocks.
- Full Text:
- Date Issued: 1994
Direct experience of God in contemporary theology
- Authors: Slater, Jennifer
- Date: 1994
- Subjects: Rahner, Karl, 1904-1984 -- Criticism and interpretation , Merton, Thomas, 1915-1968 -- Criticism and interpretation , Kelsey, Morton T. -- Criticism and interpretation , Fox, Matthew, -- 1940- -- Criticism and interpretation , Gutiérrez, Gustavo, 1928- -- Criticism and interpretation , God -- Knowableness , Experience (Religion) , God -- History of doctrines -- 20th century
- Language: English
- Type: Thesis , Masters , MTh
- Identifier: vital:1303 , http://hdl.handle.net/10962/d1016265
- Description: 'Direct experience of God' is a term frequently used by theologians without adequate clarification regarding its meaning. The understanding thereof has become increasingly complicated by the process of secularization. In the 1960's, it was repeatedly asserted that modern people could not have direct experiences of God, albeit that one could still live by faith and by commitment to the way of Jesus in a world in which, it was asserted, "God is dead". This claim, although long predominant, has been challenged by the upsurge of interest in mysticism, both Eastern and Western, and the burgeoning of Pentecostalism and the Charismatic movement, in which circles direct experience of God was frequently claimed. If direct experience of God is something natural to humanity, interpretation of it will vary in exactly the same way as interpretation of all other human experiences. This could be a possible reason for it being so very poorly integrated into everyday life, resulting in the loss of meaning and value.
- Full Text:
- Date Issued: 1994
- Authors: Slater, Jennifer
- Date: 1994
- Subjects: Rahner, Karl, 1904-1984 -- Criticism and interpretation , Merton, Thomas, 1915-1968 -- Criticism and interpretation , Kelsey, Morton T. -- Criticism and interpretation , Fox, Matthew, -- 1940- -- Criticism and interpretation , Gutiérrez, Gustavo, 1928- -- Criticism and interpretation , God -- Knowableness , Experience (Religion) , God -- History of doctrines -- 20th century
- Language: English
- Type: Thesis , Masters , MTh
- Identifier: vital:1303 , http://hdl.handle.net/10962/d1016265
- Description: 'Direct experience of God' is a term frequently used by theologians without adequate clarification regarding its meaning. The understanding thereof has become increasingly complicated by the process of secularization. In the 1960's, it was repeatedly asserted that modern people could not have direct experiences of God, albeit that one could still live by faith and by commitment to the way of Jesus in a world in which, it was asserted, "God is dead". This claim, although long predominant, has been challenged by the upsurge of interest in mysticism, both Eastern and Western, and the burgeoning of Pentecostalism and the Charismatic movement, in which circles direct experience of God was frequently claimed. If direct experience of God is something natural to humanity, interpretation of it will vary in exactly the same way as interpretation of all other human experiences. This could be a possible reason for it being so very poorly integrated into everyday life, resulting in the loss of meaning and value.
- Full Text:
- Date Issued: 1994
Development of an artificial weaning diet for the South African abalone, Haliotis midae (Haliotidae: Gastropoda)
- Authors: Knauer, Jens
- Date: 1994
- Subjects: Abalone culture -- Research -- South Africa , Ichthyology , Abalones
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5204 , http://hdl.handle.net/10962/d1004099 , Abalone culture -- Research -- South Africa , Ichthyology , Abalones
- Description: An adequate supply of diatoms during the weaning stage (generally 5 - 10 mm shell length (SL)) is one of the primary constraints to the commercial culture of the South African abalone, Haliotis midae. Because of the seriousness of the problem, a project aimed at the development of an artificial weaning diet was initiated. Initially, the chemical composition (proximate composition, amino acid, fatty acid and mineral element profile) of juvenile H. midae was analyzed, as a general lack of such information was identified in a review. Due to the lack of knowledge on the nutritional requirements of H. midae, the formulation of the weaning diet was based on the essential amino acid (EAA) pattern of the shucked tissue, and the known nutrient requirements of haliotids. Subsequently, a water stable gel and pellet form of the diet were developed. The best water stability of a gel was obtained with a 1:3 agar/gelatine mixture which retained 70.7 ± 2.7 % of its dry weight after 24 h. Starch based pellets, however, retained 89.0 ± 0.6 % of their dry weight after 24 h. In a comparative growth trial, pellets produced a significantly better increase in SL and weight than gels after only 15 days. This was probably due to the better water stability of pellets, which resulted in a better nutritional quality than in gels. The feeding behaviour on both forms of the diet did not differ. Activity patterns were exclusively nocturnal and feeding frequency was consistently low. The percentage composition of the pelleted weaning diet, on a dry weight basis, was 5 % casein, 15 % gelatine, 15 % fish meal, 10 % Spirulina spp., 2.5 % fish oil, 2.5 % sunflower oil, 21.0 % dextrin, 23.0 % starch, 4.0 % of a mineral and 2.0 % of a vitamin mixture. The correlation coefficient between the EAA pattern of H. midae and the dietary EAA pattern was r⁷= 0.8989. Pellets were fed to juveniles in a 30 day growth trial to study the effect of photoperiod (12, 16, 20 and 23 hours of darkness) on growth and general nutritional parameters. A comparative experiment feeding diatoms was conducted under a 12hL: 12hD light regime at the same time. The SL and weight of the juveniles did not increase significantly with an increase in hours of darkness. The growth of juveniles fed on pellets did not differ significantly from those fed on diatoms. Percentage feed consumption (PFC), percentage feeding rate (PFR), feed conversion ratio (FCR), protein efficiency ratio (PER) and percentage protein deposited (PPD) were determined for the animals fed on pellets. None of the parameters were significantly affected by photoperiod. However, there were trends in that PFC increased with longer periods of darkness, while PPD decreased. The FCRs (0.44 ± 0.04 to 0.60 ± 0.19) and PERs (5.06 ± 1.74 to 6.64 ± 0.77) indicated that juveniles used the feed, and in particular the protein, very efficiently. Photoperiod did not have an effect on the specific activity of the digestive enzymes amylase, protease and lipase. The specific activity of amylase in the juveniles fed on diatoms was significantly higher than in the pellet fed groups. This was surprising as the main carbohydrate of diatoms is the ß-(l-3) glucan chrysolaminarin, and not starch, a ß-(l-4) glucan. Protease specific activity, on the other hand, was significantly higher in the pellet fed groups, indicating an ability to adapt to the high protein content in the artificial diet (35.48 %), compared to diatoms which had a protein content of 5 %. The specific activity of lipase did not differ significantly between groups, probably because of a similar lipid concentration (5 - 10 %) in diatoms and pellets. Finally, the effect of stocking density, ranging from 1250 to 10,000 juveniles/m2, on the growth of juveniles was evaluated. A model of hatchery productivity was developed based on this investigation. Hatchery productivity was defined as the number of juveniles per unit space reared through to the grow-out stage per unit time. The model predicted that maximum productivity would be achieved at a stocking density of 10,000 juveniles/m2. The results have shown that H. midae can be successfully weaned on an artificial diet, as the growth on the diet was not significantly different to growth obtained on diatoms. Long-term growth trials are needed to confirm these results. The importance of standardized experiments on the nutritional requirements and digestibility of abalone was emphasized. The importance of improved artificial diets, optimal culture conditions, as well as the application of biotechnological techniques to further abalone aquaculture was highlighted.
- Full Text:
- Date Issued: 1994
- Authors: Knauer, Jens
- Date: 1994
- Subjects: Abalone culture -- Research -- South Africa , Ichthyology , Abalones
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5204 , http://hdl.handle.net/10962/d1004099 , Abalone culture -- Research -- South Africa , Ichthyology , Abalones
- Description: An adequate supply of diatoms during the weaning stage (generally 5 - 10 mm shell length (SL)) is one of the primary constraints to the commercial culture of the South African abalone, Haliotis midae. Because of the seriousness of the problem, a project aimed at the development of an artificial weaning diet was initiated. Initially, the chemical composition (proximate composition, amino acid, fatty acid and mineral element profile) of juvenile H. midae was analyzed, as a general lack of such information was identified in a review. Due to the lack of knowledge on the nutritional requirements of H. midae, the formulation of the weaning diet was based on the essential amino acid (EAA) pattern of the shucked tissue, and the known nutrient requirements of haliotids. Subsequently, a water stable gel and pellet form of the diet were developed. The best water stability of a gel was obtained with a 1:3 agar/gelatine mixture which retained 70.7 ± 2.7 % of its dry weight after 24 h. Starch based pellets, however, retained 89.0 ± 0.6 % of their dry weight after 24 h. In a comparative growth trial, pellets produced a significantly better increase in SL and weight than gels after only 15 days. This was probably due to the better water stability of pellets, which resulted in a better nutritional quality than in gels. The feeding behaviour on both forms of the diet did not differ. Activity patterns were exclusively nocturnal and feeding frequency was consistently low. The percentage composition of the pelleted weaning diet, on a dry weight basis, was 5 % casein, 15 % gelatine, 15 % fish meal, 10 % Spirulina spp., 2.5 % fish oil, 2.5 % sunflower oil, 21.0 % dextrin, 23.0 % starch, 4.0 % of a mineral and 2.0 % of a vitamin mixture. The correlation coefficient between the EAA pattern of H. midae and the dietary EAA pattern was r⁷= 0.8989. Pellets were fed to juveniles in a 30 day growth trial to study the effect of photoperiod (12, 16, 20 and 23 hours of darkness) on growth and general nutritional parameters. A comparative experiment feeding diatoms was conducted under a 12hL: 12hD light regime at the same time. The SL and weight of the juveniles did not increase significantly with an increase in hours of darkness. The growth of juveniles fed on pellets did not differ significantly from those fed on diatoms. Percentage feed consumption (PFC), percentage feeding rate (PFR), feed conversion ratio (FCR), protein efficiency ratio (PER) and percentage protein deposited (PPD) were determined for the animals fed on pellets. None of the parameters were significantly affected by photoperiod. However, there were trends in that PFC increased with longer periods of darkness, while PPD decreased. The FCRs (0.44 ± 0.04 to 0.60 ± 0.19) and PERs (5.06 ± 1.74 to 6.64 ± 0.77) indicated that juveniles used the feed, and in particular the protein, very efficiently. Photoperiod did not have an effect on the specific activity of the digestive enzymes amylase, protease and lipase. The specific activity of amylase in the juveniles fed on diatoms was significantly higher than in the pellet fed groups. This was surprising as the main carbohydrate of diatoms is the ß-(l-3) glucan chrysolaminarin, and not starch, a ß-(l-4) glucan. Protease specific activity, on the other hand, was significantly higher in the pellet fed groups, indicating an ability to adapt to the high protein content in the artificial diet (35.48 %), compared to diatoms which had a protein content of 5 %. The specific activity of lipase did not differ significantly between groups, probably because of a similar lipid concentration (5 - 10 %) in diatoms and pellets. Finally, the effect of stocking density, ranging from 1250 to 10,000 juveniles/m2, on the growth of juveniles was evaluated. A model of hatchery productivity was developed based on this investigation. Hatchery productivity was defined as the number of juveniles per unit space reared through to the grow-out stage per unit time. The model predicted that maximum productivity would be achieved at a stocking density of 10,000 juveniles/m2. The results have shown that H. midae can be successfully weaned on an artificial diet, as the growth on the diet was not significantly different to growth obtained on diatoms. Long-term growth trials are needed to confirm these results. The importance of standardized experiments on the nutritional requirements and digestibility of abalone was emphasized. The importance of improved artificial diets, optimal culture conditions, as well as the application of biotechnological techniques to further abalone aquaculture was highlighted.
- Full Text:
- Date Issued: 1994
Delineation of buried stream channels using geophysical techniques
- Authors: Biedler, Murray W
- Date: 1994
- Subjects: Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4823 , http://hdl.handle.net/10962/d1005498 , Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Description: This study sets out to evaluate the use of geophysical methods for delineating buried stream channels, which can act as zones of preferential flow within a less hydraulically conductive aquifer. This information is important for gaining an understanding of flow dynamics of alluvial systems. The most reliable method of delineating the dimensions of aquifers is by drilling, which is an expensive proposition and is best preceded by a preliminary geophysical study to help define target zones for a drilling program. The study area is located adjacent to the Coerney River in the Sundays River Valley. Geologically it consists of approximately 5 metres of alluvial fines, covering 3 metres of coarse cobbles and boulders, all underlain by alternating siltstone and sandstone beds of indeterminate thickness. Throughout the area the water is very shallow at approximately 2 metres depth and the groundwater tends to be very saline. An air photo study revealed an old oxbow channel that had been covered over by subsequent agricultural land use. The geophysical methods available for the study were portable seismic refraction, electrical resistivity and electromagnetics. Preliminary field tests clearly showed that seismics did not produce valid results. The methods of electrical resistivity and electromagnetics produced good data and were subjected to further assessment. A grid was surveyed over the study area and both geophysical methods were applied at regularly spaced stations. Soil samples were taken over the same survey grid and analyzed for electrical conductivity in a soils laboratory. The results were compared to the geophysical data in an attempt to quantify the relationship between geophysical response and soil salinity. The data from the electromagnetic survey showed areas of low electrical conductivity which was a possible indication of zones of preferential groundwater flow. A transect of boreholes was drilled over selected electrical conductivity lows and successfully intersected the buried stream channel. A comparison of the borehole logs with the layered earth models from the Vertical Electrical Soundings indicated that the electrical resistivity method was not responding to the features of the buried stream channel and the cobblestone layer. This proved the electromagnetic method to be more valuable for this particular study
- Full Text:
- Date Issued: 1994
- Authors: Biedler, Murray W
- Date: 1994
- Subjects: Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4823 , http://hdl.handle.net/10962/d1005498 , Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Description: This study sets out to evaluate the use of geophysical methods for delineating buried stream channels, which can act as zones of preferential flow within a less hydraulically conductive aquifer. This information is important for gaining an understanding of flow dynamics of alluvial systems. The most reliable method of delineating the dimensions of aquifers is by drilling, which is an expensive proposition and is best preceded by a preliminary geophysical study to help define target zones for a drilling program. The study area is located adjacent to the Coerney River in the Sundays River Valley. Geologically it consists of approximately 5 metres of alluvial fines, covering 3 metres of coarse cobbles and boulders, all underlain by alternating siltstone and sandstone beds of indeterminate thickness. Throughout the area the water is very shallow at approximately 2 metres depth and the groundwater tends to be very saline. An air photo study revealed an old oxbow channel that had been covered over by subsequent agricultural land use. The geophysical methods available for the study were portable seismic refraction, electrical resistivity and electromagnetics. Preliminary field tests clearly showed that seismics did not produce valid results. The methods of electrical resistivity and electromagnetics produced good data and were subjected to further assessment. A grid was surveyed over the study area and both geophysical methods were applied at regularly spaced stations. Soil samples were taken over the same survey grid and analyzed for electrical conductivity in a soils laboratory. The results were compared to the geophysical data in an attempt to quantify the relationship between geophysical response and soil salinity. The data from the electromagnetic survey showed areas of low electrical conductivity which was a possible indication of zones of preferential groundwater flow. A transect of boreholes was drilled over selected electrical conductivity lows and successfully intersected the buried stream channel. A comparison of the borehole logs with the layered earth models from the Vertical Electrical Soundings indicated that the electrical resistivity method was not responding to the features of the buried stream channel and the cobblestone layer. This proved the electromagnetic method to be more valuable for this particular study
- Full Text:
- Date Issued: 1994
Cyclic voltammetry and spectroelectrochemistry of rhodium phthalocyanines
- Authors: Nyokong, Tebello
- Date: 1994
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295486 , vital:57346 , xlink:href="https://doi.org/10.1039/DT9940001359"
- Description: The electrochemistry of RhIII(pc)(pc = phthalocyanine dianion) complexes containing chloride, pyridine, dimethyl sulfoxide (dmso) and cyanide as axial ligands was investigated by cyclic voltammetry and UV/VIS spectroelectrochemistry. The compounds were K[Rh(pc)(CN)2], [Rh(pc)(Cl)(py)] and [Rh(pc)Cl(dmso)]. For all of these the first oxidation occurs at the phthalocyanine ligand with the formation of a π-cation radical species. The addition of one electron to the complexes leads to one of two different reduction products depending on the nature of the axial ligands. The first reduction of [Rh(pc)Cl(py)] and [Rh(pc)Cl(dmso)] occurs at the metal, followed by rapid dimerization of the reduced species. The first and subsequent reductions of K[Rh(pc)(CN)2] occur at the ring.
- Full Text:
- Date Issued: 1994
- Authors: Nyokong, Tebello
- Date: 1994
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295486 , vital:57346 , xlink:href="https://doi.org/10.1039/DT9940001359"
- Description: The electrochemistry of RhIII(pc)(pc = phthalocyanine dianion) complexes containing chloride, pyridine, dimethyl sulfoxide (dmso) and cyanide as axial ligands was investigated by cyclic voltammetry and UV/VIS spectroelectrochemistry. The compounds were K[Rh(pc)(CN)2], [Rh(pc)(Cl)(py)] and [Rh(pc)Cl(dmso)]. For all of these the first oxidation occurs at the phthalocyanine ligand with the formation of a π-cation radical species. The addition of one electron to the complexes leads to one of two different reduction products depending on the nature of the axial ligands. The first reduction of [Rh(pc)Cl(py)] and [Rh(pc)Cl(dmso)] occurs at the metal, followed by rapid dimerization of the reduced species. The first and subsequent reductions of K[Rh(pc)(CN)2] occur at the ring.
- Full Text:
- Date Issued: 1994
Cyclic voltammetry and photooxidation of molybdenum (V) phthalocyanine
- Authors: Nyokong, Tebello
- Date: 1994
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295475 , vital:57344 , xlink:href="https://doi.org/10.1016/S0277-5387(00)86594-8"
- Description: Cyclic voltammetry of OMoV(OH)Pc in chloronaphthalene shows two quasi-reversible oxidation couples at 0.38 and 1.22 V and three quasi-reversible reduction couples at −0.74, −1.15 and −1.85 V vs S.C.E. Bulk electrolysis of OMoV(OH)Pc (Pc2 = phthalocyanine dianion) shows that the first oxidation couple is due to the oxidation of the central MoV metal to MoVI and the first reduction couple due to reduction to OMoIVPc. Cyclic voltammetry and spectroelectrochemistry in DMSO also showed redox activity at the metal. Further reductions or oxidations in OMoVPc complexes occur at the phthalocyanine ring. OMoV(OH)Pc is readily photooxidized at the metal in the presence dichloromethane or dichlorobenzene, with the formation of OMoVIPc species.
- Full Text:
- Date Issued: 1994
- Authors: Nyokong, Tebello
- Date: 1994
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295475 , vital:57344 , xlink:href="https://doi.org/10.1016/S0277-5387(00)86594-8"
- Description: Cyclic voltammetry of OMoV(OH)Pc in chloronaphthalene shows two quasi-reversible oxidation couples at 0.38 and 1.22 V and three quasi-reversible reduction couples at −0.74, −1.15 and −1.85 V vs S.C.E. Bulk electrolysis of OMoV(OH)Pc (Pc2 = phthalocyanine dianion) shows that the first oxidation couple is due to the oxidation of the central MoV metal to MoVI and the first reduction couple due to reduction to OMoIVPc. Cyclic voltammetry and spectroelectrochemistry in DMSO also showed redox activity at the metal. Further reductions or oxidations in OMoVPc complexes occur at the phthalocyanine ring. OMoV(OH)Pc is readily photooxidized at the metal in the presence dichloromethane or dichlorobenzene, with the formation of OMoVIPc species.
- Full Text:
- Date Issued: 1994
Constituent processes of leaf senescence in Hordeum vulgare cv. Dyan
- Afitlhile, Meshack Mosimanegape
- Authors: Afitlhile, Meshack Mosimanegape
- Date: 1994
- Subjects: Leaves , Leaves -- Development
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4184 , http://hdl.handle.net/10962/d1003752
- Description: Changes in chlorophyll content, carotenoid content and composition, abscisic acid and phaseic acid levels, hydrolytic enzyme activity and polypeptide pattern were monitored during senescence of the primary attached leaves of Hordeum vulgare L. cv. Dyan. Senescence occurred due to the normal course of leaf development or was induced by incubation of leaves in darkness. Loss of chlorophyll and total leaf protein was retarded in light whereas it continued rapidly in leaves from dark-incubated seedlings. Chlorophyll alb ratio increased with the progression of senescence, suggesting that chlorophyll b was referentially degraded during this process. Loss of total protein coincided with enhanced activity of acid and neutral proteases. In contrast, loss of chlorophyll was not accompanied by an increase in· peroxidase activity, suggesting that this enzyme was not responsible for initiating chlorophyll breakdown. Carotenoid and abscisic acid levels were monitored in the same tissue extracts. The results obtained show that the increase in endogenous levels of abscisic acid, induced by senescence, correlated with enhanced epoxidation of the xanthophyll cycle, ie., increased conversion of zeaxanthin to antheraxanthin and all-trans-violaxanthin. In addition, an increase in abscisic acid levels occurred concomitant with a decrease in all-trans-violaxanthin and 9'-cis-neoxanthin, suggesting an apparent 1:1 relationship on a molar basis. It is therefore proposed that enhanced abscisic acid production, due to foliar senescence, arises from fluctuations in carotenoid turnover. Polypeptide patterns in isolated chloroplasts, purified thylakoid and stromal fractions were very similar for leaves incubated in either light or darkness. A decrease in intensity of bands was observed in isolated chloroplasts and stromal fractions. Intensity of bands in thylakoids remained unchanged with the progression of senescence. Protein standards of peroxidase and lipoxygenase co-migrated with proteins of the isolated chloroplast. Although tentative, some proteins of the chloroplast may be representative of precursors of hydrolytic enzymes which are known to increase during senescence.
- Full Text:
- Date Issued: 1994
- Authors: Afitlhile, Meshack Mosimanegape
- Date: 1994
- Subjects: Leaves , Leaves -- Development
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4184 , http://hdl.handle.net/10962/d1003752
- Description: Changes in chlorophyll content, carotenoid content and composition, abscisic acid and phaseic acid levels, hydrolytic enzyme activity and polypeptide pattern were monitored during senescence of the primary attached leaves of Hordeum vulgare L. cv. Dyan. Senescence occurred due to the normal course of leaf development or was induced by incubation of leaves in darkness. Loss of chlorophyll and total leaf protein was retarded in light whereas it continued rapidly in leaves from dark-incubated seedlings. Chlorophyll alb ratio increased with the progression of senescence, suggesting that chlorophyll b was referentially degraded during this process. Loss of total protein coincided with enhanced activity of acid and neutral proteases. In contrast, loss of chlorophyll was not accompanied by an increase in· peroxidase activity, suggesting that this enzyme was not responsible for initiating chlorophyll breakdown. Carotenoid and abscisic acid levels were monitored in the same tissue extracts. The results obtained show that the increase in endogenous levels of abscisic acid, induced by senescence, correlated with enhanced epoxidation of the xanthophyll cycle, ie., increased conversion of zeaxanthin to antheraxanthin and all-trans-violaxanthin. In addition, an increase in abscisic acid levels occurred concomitant with a decrease in all-trans-violaxanthin and 9'-cis-neoxanthin, suggesting an apparent 1:1 relationship on a molar basis. It is therefore proposed that enhanced abscisic acid production, due to foliar senescence, arises from fluctuations in carotenoid turnover. Polypeptide patterns in isolated chloroplasts, purified thylakoid and stromal fractions were very similar for leaves incubated in either light or darkness. A decrease in intensity of bands was observed in isolated chloroplasts and stromal fractions. Intensity of bands in thylakoids remained unchanged with the progression of senescence. Protein standards of peroxidase and lipoxygenase co-migrated with proteins of the isolated chloroplast. Although tentative, some proteins of the chloroplast may be representative of precursors of hydrolytic enzymes which are known to increase during senescence.
- Full Text:
- Date Issued: 1994
Conditions of service of SAMWU staff
- SAMWU
- Authors: SAMWU
- Date: 1994
- Subjects: SAMWU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/178916 , vital:43019
- Description: This document is as adopted by the SAMWU NEC in November 1994. It serves to define the wages and conditions of employment applicable to all SAMWU staff and is the only conditions of employment document of the union. Employees who were staff of a pre-existing trade union which merged with SAMWU who have conditions which were previously declared personal to holder ( in terms of merger agreements ) are required to examine this document and to individually register where they, consider that their terms differ from this document. No improved condition hereby introduced can be taken to apply to such employees as a matter of right . They have a choice of registering specific conditions as ” personal to holder " or converting to the full set of conditions as contained herein. Where they register a condition as personal to holder the NEC will decide whether new conditions hereby introduced are also applicable to them. It is further recorded that whilst these conditions of service are open to be ammended from time to time ; as-the NEC may decide , any representations for amendments shall normally only be considered during the later part*of-each year.
- Full Text:
- Date Issued: 1994
- Authors: SAMWU
- Date: 1994
- Subjects: SAMWU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/178916 , vital:43019
- Description: This document is as adopted by the SAMWU NEC in November 1994. It serves to define the wages and conditions of employment applicable to all SAMWU staff and is the only conditions of employment document of the union. Employees who were staff of a pre-existing trade union which merged with SAMWU who have conditions which were previously declared personal to holder ( in terms of merger agreements ) are required to examine this document and to individually register where they, consider that their terms differ from this document. No improved condition hereby introduced can be taken to apply to such employees as a matter of right . They have a choice of registering specific conditions as ” personal to holder " or converting to the full set of conditions as contained herein. Where they register a condition as personal to holder the NEC will decide whether new conditions hereby introduced are also applicable to them. It is further recorded that whilst these conditions of service are open to be ammended from time to time ; as-the NEC may decide , any representations for amendments shall normally only be considered during the later part*of-each year.
- Full Text:
- Date Issued: 1994
Computer assisted language learning for academic development programmes : an appraisal of needs, resources and approaches
- Authors: Collett, Philip Godfrey
- Date: 1994
- Subjects: English language -- Computer-assisted instruction Language arts -- Computer-assisted instruction Language acquisition Computers and literacy English language -- Study and teaching -- Foreign speakers Computer-assisted instruction
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1457 , http://hdl.handle.net/10962/d1003338
- Description: A major objective of Academic Development Programmes is to support the student in acquiring a level of language competence which is sufficient to enable the student to cope with the linguistic demands of academic courses. Language teaching programmes in the Academic Development context in South Africa suffer from a number of constraints: staffing, time on task, relevance, and difficulty of integration with learning in other coUrses. A review of developments in the field of Computer Assisted Language Learning (CALL) shows that computers can be used to support language learning. CALL materials range from simple instructional programs to powerful linguistic research tools and need to be integrated into wider language programmes so as to support and enhance other teaching and learning activities. However, relatively little research has been done to investigate the feasibility and effectiveness of CALL in language development courses within Academic Development programmes in South Africa. The development of a system designed to enable students to practise proof-reading and editing is described and evaluated. Suggestions are made for using this system with other CALL materials within a computer assisted language development environment. It is argued that CALL can be used feasibly and effectively in this environment to enhance learning and to counteract constraints.
- Full Text:
- Date Issued: 1994
- Authors: Collett, Philip Godfrey
- Date: 1994
- Subjects: English language -- Computer-assisted instruction Language arts -- Computer-assisted instruction Language acquisition Computers and literacy English language -- Study and teaching -- Foreign speakers Computer-assisted instruction
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1457 , http://hdl.handle.net/10962/d1003338
- Description: A major objective of Academic Development Programmes is to support the student in acquiring a level of language competence which is sufficient to enable the student to cope with the linguistic demands of academic courses. Language teaching programmes in the Academic Development context in South Africa suffer from a number of constraints: staffing, time on task, relevance, and difficulty of integration with learning in other coUrses. A review of developments in the field of Computer Assisted Language Learning (CALL) shows that computers can be used to support language learning. CALL materials range from simple instructional programs to powerful linguistic research tools and need to be integrated into wider language programmes so as to support and enhance other teaching and learning activities. However, relatively little research has been done to investigate the feasibility and effectiveness of CALL in language development courses within Academic Development programmes in South Africa. The development of a system designed to enable students to practise proof-reading and editing is described and evaluated. Suggestions are made for using this system with other CALL materials within a computer assisted language development environment. It is argued that CALL can be used feasibly and effectively in this environment to enhance learning and to counteract constraints.
- Full Text:
- Date Issued: 1994
Comparative aspects of the reproductive biology of seabreams (Pisces: Sparidae)
- Authors: Garratt, Patrick Ashworth
- Date: 1994
- Subjects: Sparidae -- Physiology Sparidae -- Reproduction
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5245 , http://hdl.handle.net/10962/d1005088
- Description: Sexuality in seabreams (Sparidae) is considered to be more complex than in any other family of fishes. Early work indicated five reproductive styles within the family: protandry, protogyny, simultaneous hermaphroditism, rudimentary hermaphroditism and gonochorism. More recently two reproductive styles have been suggested: sex change (protandry and protogyny) and secondary gonochorism (rudimentary hermaphrodites). The need for detailed descriptions of sex differentiation, gonad development and spawning behaviour in this family has been identified by a number of workers in this field. The aims of the present study were: i) to provide accurate, detailed descriptions and comparisons of gonadal development in representatives of each reproductive style, ii) to investigate their spawning strategies, and iii) to relate these findings to current theories on hermaphroditism and sex change in fishes. Four species were investigated. Slinger, Chrysoblephus puniceus, the only known protogynous hermaphrodite in Natal. Santer, Cheimerius nufar, described in the literature as a rudimentary hermaphrodite. Riverbream, Acanthopagrus berda suspected to be a protandrous hermaphrodite. Natal stump nose, Rhabdosargus sarba, reported elsewhere as a protandrous hermaphrodite. Detailed histological analysis showed that morphological and cytological development of all gonads proceeded initially in a female direction, irrespective of reproductive style, but that differentiating gonads of protandrous and protogynous hermaphrodites could easily be distinguished from one another. Early gonadal development was similar in R. sarba and A. berda with gonadal primordia differentiating into distinctly bisexual organs. In C. puniceus and C. nufar gonadal primordia differentiated into ovaries with reduced, inert male elements in the tunica albuginea. Sex differentiation occurred relatively late (100-150mm fork length) in all the species investigated. Few cells conforming to primordial germ cells (PGC's) described in other teleosts were identified. These cells only became evident after the appearance of gonial cells and their identity is questioned. Gonial cells appeared to develop within less-electron-dense cysts of cells. Gonial cells in presumptive male and female elements could not be distinguished from one another morphologically, suggesting the bipotentiality of these cells. All R. sarba and A. berda gonads pass through a predominantly male phase and all fish function first as males, indicating protandrous sex change in both species. All C. puniceus and C. nufar gonads develop initially into ovaries. Sex change thus occurs in both species and protogyny in C. puniceus is confirmed. In C. nufar, sex change may occur before or after sexual maturity and its reproductive style remains uncertain. Investigations into the spawning habits of A. berda have shown that this species spawns inside the Kosi estuary at night. Eggs are released during peak ebb tides. Spawning occurs in large aggregations and several to many males compete to spawn with individual females. This spawning strategy does not conform to predictions made from the size advantage model for protandrous species. Chrysoblephus puniceus appears to have preferential spawning sites on down-current outer reef margins. Spawning was not observed in this species, but changes in behaviour, social structure and colour during the spawning season suggest that it may have a mating system similar to several protogynous labrids and scarids, in which territories are temporary. Cheimerius nufar has a similar mating system. Temporary territories are established by large males during the spawning season, which extends from August to November. Mating is by pair-spawning and dominant territorial males obtain a disproportionate number of matings. 'Streaking' appears to represent an alternative mating strategy for males until they attain a sufficient size to establish and defend territories. The mating pattern of C. nufar suggests that it is either a gonochorist which does not conform to current theoretical predictions; or that it is a protogynous hermaphrodite incorrectly diagnosed as a rudimentary hermaphrodite; or that protogyny in the Sparidae is an ancestral condition and C. nufar is in the process of evolutionary change from a protogynous to a gonochoristic form (or visa versa).
- Full Text:
- Date Issued: 1994
- Authors: Garratt, Patrick Ashworth
- Date: 1994
- Subjects: Sparidae -- Physiology Sparidae -- Reproduction
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5245 , http://hdl.handle.net/10962/d1005088
- Description: Sexuality in seabreams (Sparidae) is considered to be more complex than in any other family of fishes. Early work indicated five reproductive styles within the family: protandry, protogyny, simultaneous hermaphroditism, rudimentary hermaphroditism and gonochorism. More recently two reproductive styles have been suggested: sex change (protandry and protogyny) and secondary gonochorism (rudimentary hermaphrodites). The need for detailed descriptions of sex differentiation, gonad development and spawning behaviour in this family has been identified by a number of workers in this field. The aims of the present study were: i) to provide accurate, detailed descriptions and comparisons of gonadal development in representatives of each reproductive style, ii) to investigate their spawning strategies, and iii) to relate these findings to current theories on hermaphroditism and sex change in fishes. Four species were investigated. Slinger, Chrysoblephus puniceus, the only known protogynous hermaphrodite in Natal. Santer, Cheimerius nufar, described in the literature as a rudimentary hermaphrodite. Riverbream, Acanthopagrus berda suspected to be a protandrous hermaphrodite. Natal stump nose, Rhabdosargus sarba, reported elsewhere as a protandrous hermaphrodite. Detailed histological analysis showed that morphological and cytological development of all gonads proceeded initially in a female direction, irrespective of reproductive style, but that differentiating gonads of protandrous and protogynous hermaphrodites could easily be distinguished from one another. Early gonadal development was similar in R. sarba and A. berda with gonadal primordia differentiating into distinctly bisexual organs. In C. puniceus and C. nufar gonadal primordia differentiated into ovaries with reduced, inert male elements in the tunica albuginea. Sex differentiation occurred relatively late (100-150mm fork length) in all the species investigated. Few cells conforming to primordial germ cells (PGC's) described in other teleosts were identified. These cells only became evident after the appearance of gonial cells and their identity is questioned. Gonial cells appeared to develop within less-electron-dense cysts of cells. Gonial cells in presumptive male and female elements could not be distinguished from one another morphologically, suggesting the bipotentiality of these cells. All R. sarba and A. berda gonads pass through a predominantly male phase and all fish function first as males, indicating protandrous sex change in both species. All C. puniceus and C. nufar gonads develop initially into ovaries. Sex change thus occurs in both species and protogyny in C. puniceus is confirmed. In C. nufar, sex change may occur before or after sexual maturity and its reproductive style remains uncertain. Investigations into the spawning habits of A. berda have shown that this species spawns inside the Kosi estuary at night. Eggs are released during peak ebb tides. Spawning occurs in large aggregations and several to many males compete to spawn with individual females. This spawning strategy does not conform to predictions made from the size advantage model for protandrous species. Chrysoblephus puniceus appears to have preferential spawning sites on down-current outer reef margins. Spawning was not observed in this species, but changes in behaviour, social structure and colour during the spawning season suggest that it may have a mating system similar to several protogynous labrids and scarids, in which territories are temporary. Cheimerius nufar has a similar mating system. Temporary territories are established by large males during the spawning season, which extends from August to November. Mating is by pair-spawning and dominant territorial males obtain a disproportionate number of matings. 'Streaking' appears to represent an alternative mating strategy for males until they attain a sufficient size to establish and defend territories. The mating pattern of C. nufar suggests that it is either a gonochorist which does not conform to current theoretical predictions; or that it is a protogynous hermaphrodite incorrectly diagnosed as a rudimentary hermaphrodite; or that protogyny in the Sparidae is an ancestral condition and C. nufar is in the process of evolutionary change from a protogynous to a gonochoristic form (or visa versa).
- Full Text:
- Date Issued: 1994
Cogitator : a parallel, fuzzy, database-driven expert system
- Authors: Baise, Paul
- Date: 1994 , 2012-10-08
- Subjects: Expert systems (Computer science) , Artificial intelligence -- Computer programs , System design , Cogitator (Computer system)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4667 , http://hdl.handle.net/10962/d1006684 , Expert systems (Computer science) , Artificial intelligence -- Computer programs , System design , Cogitator (Computer system)
- Description: The quest to build anthropomorphic machines has led researchers to focus on knowledge and the manipulation thereof. Recently, the expert system was proposed as a solution, working well in small, well understood domains. However these initial attempts highlighted the tedious process associated with building systems to display intelligence, the most notable being the Knowledge Acquisition Bottleneck. Attempts to circumvent this problem have led researchers to propose the use of machine learning databases as a source of knowledge. Attempts to utilise databases as sources of knowledge has led to the development Database-Driven Expert Systems. Furthermore, it has been ascertained that a requisite for intelligent systems is powerful computation. In response to these problems and proposals, a new type of database-driven expert system, Cogitator is proposed. It is shown to circumvent the Knowledge Acquisition Bottleneck and posess many other advantages over both traditional expert systems and connectionist systems, whilst having non-serious disadvantages. , KMBT_223
- Full Text:
- Date Issued: 1994
- Authors: Baise, Paul
- Date: 1994 , 2012-10-08
- Subjects: Expert systems (Computer science) , Artificial intelligence -- Computer programs , System design , Cogitator (Computer system)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4667 , http://hdl.handle.net/10962/d1006684 , Expert systems (Computer science) , Artificial intelligence -- Computer programs , System design , Cogitator (Computer system)
- Description: The quest to build anthropomorphic machines has led researchers to focus on knowledge and the manipulation thereof. Recently, the expert system was proposed as a solution, working well in small, well understood domains. However these initial attempts highlighted the tedious process associated with building systems to display intelligence, the most notable being the Knowledge Acquisition Bottleneck. Attempts to circumvent this problem have led researchers to propose the use of machine learning databases as a source of knowledge. Attempts to utilise databases as sources of knowledge has led to the development Database-Driven Expert Systems. Furthermore, it has been ascertained that a requisite for intelligent systems is powerful computation. In response to these problems and proposals, a new type of database-driven expert system, Cogitator is proposed. It is shown to circumvent the Knowledge Acquisition Bottleneck and posess many other advantages over both traditional expert systems and connectionist systems, whilst having non-serious disadvantages. , KMBT_223
- Full Text:
- Date Issued: 1994
Centralised bargaining - Where to CWIU
- Chemical Workers Industrial Union (CWIU)
- Authors: Chemical Workers Industrial Union (CWIU)
- Date: 1994
- Subjects: CWIU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/170148 , vital:41862
- Description: Since the late 1980's, there has been a serious realisation on the part of Cosatu and CWIU leadership, of the need for Centralised Bargaining. Two broad areas of concern which pressurised us in this direction were: 1) The low level of class consciousness on the part of the majority of members during this period especially with regard to the complete lack of solidarity around wage struggles. 2) The organisational incapacity of the unions to cope with the excessive demands of plant based bargaining. This wasted resources and undermined the quality of work and achievement of annual wage bargaining. Faced by this reality, achieving consensus on the need for a campaign to achieve centralised bargaining at leadership level was relatively easy. Unions in other sectors eg. metal, mining, clothing, textile and the public sector, regularly set examples of what could be achieved by well run centralised bargaining. Numsa's experience illustrated the strengths and pitfalls of centralised bargaining - ie. Numsa's mandating and report back processes, the Mercedes Benz strike by opponents to the "one bite at the cherry".
- Full Text:
- Date Issued: 1994
- Authors: Chemical Workers Industrial Union (CWIU)
- Date: 1994
- Subjects: CWIU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/170148 , vital:41862
- Description: Since the late 1980's, there has been a serious realisation on the part of Cosatu and CWIU leadership, of the need for Centralised Bargaining. Two broad areas of concern which pressurised us in this direction were: 1) The low level of class consciousness on the part of the majority of members during this period especially with regard to the complete lack of solidarity around wage struggles. 2) The organisational incapacity of the unions to cope with the excessive demands of plant based bargaining. This wasted resources and undermined the quality of work and achievement of annual wage bargaining. Faced by this reality, achieving consensus on the need for a campaign to achieve centralised bargaining at leadership level was relatively easy. Unions in other sectors eg. metal, mining, clothing, textile and the public sector, regularly set examples of what could be achieved by well run centralised bargaining. Numsa's experience illustrated the strengths and pitfalls of centralised bargaining - ie. Numsa's mandating and report back processes, the Mercedes Benz strike by opponents to the "one bite at the cherry".
- Full Text:
- Date Issued: 1994
Case studies of tutors' responses to student writing and the way in which students interpret these
- Authors: Paxton, Moragh Isobel Jane
- Date: 1994
- Subjects: Written communication -- Study and teaching -- South Africa Written communication -- South Africa -- Case studies Grading and marking (Students) -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1430 , http://hdl.handle.net/10962/d1003311
- Description: This thesis examines tutor feedback on student essays to ascertain the extent to which these responses assist in teaching the academic and specific disciplinary conventions and to determine what is effective feedback and what is not. The investigation constituted an evaluation of a small sample of essays and the framework for this evaluation was developed from a study of current theories of literacy and language teaching. It was further informed by data gathered from interviews with students and tutors and questionnaires completed by them. This was done in order to establish how students interpret and react to feedback and to demonstrate the level of understanding between tutors and students in this mode of communication. The conclusion was that tutor feedback can provide a valuable method for teaching the discourse of the discipline. However, results of the study revealed that communication often breaks down because tutors and students do not share a common language for talking about academic discourse and because students may not have understood the requirements of the task. In addition, the study found that responses to a small group of essays in the lowest mark category and written by second language students, were very inadequate. As the researcher, I concluded that graduate tutors were not well equipped for the task of dealing with these weaker essays. I have made suggestions for future research in this area and I believe that the data from this case study will provide valuable ideas for training tutors for responding to student essays.
- Full Text:
- Date Issued: 1994
- Authors: Paxton, Moragh Isobel Jane
- Date: 1994
- Subjects: Written communication -- Study and teaching -- South Africa Written communication -- South Africa -- Case studies Grading and marking (Students) -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1430 , http://hdl.handle.net/10962/d1003311
- Description: This thesis examines tutor feedback on student essays to ascertain the extent to which these responses assist in teaching the academic and specific disciplinary conventions and to determine what is effective feedback and what is not. The investigation constituted an evaluation of a small sample of essays and the framework for this evaluation was developed from a study of current theories of literacy and language teaching. It was further informed by data gathered from interviews with students and tutors and questionnaires completed by them. This was done in order to establish how students interpret and react to feedback and to demonstrate the level of understanding between tutors and students in this mode of communication. The conclusion was that tutor feedback can provide a valuable method for teaching the discourse of the discipline. However, results of the study revealed that communication often breaks down because tutors and students do not share a common language for talking about academic discourse and because students may not have understood the requirements of the task. In addition, the study found that responses to a small group of essays in the lowest mark category and written by second language students, were very inadequate. As the researcher, I concluded that graduate tutors were not well equipped for the task of dealing with these weaker essays. I have made suggestions for future research in this area and I believe that the data from this case study will provide valuable ideas for training tutors for responding to student essays.
- Full Text:
- Date Issued: 1994
Biocatalytic and biomimetic studies of polyphenol oxidase
- Authors: Burton, Stephanie Gail
- Date: 1994
- Subjects: Phenol oxidase Polyphenols Oxidases
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4028 , http://hdl.handle.net/10962/d1004088
- Description: Mushroom polyphenol oxidase (EC 1.14.18.1) was investigated to determine its potential for application as a biocatalyst in the synthesis of o-quinones, in organic medium. In order to determine the kinetic properties of the biocatalyst, a system was devised which comprised an immobilised polyphenol oxidase extract, functioning in chloroform. The system was hydrated by the addition of buffer. A simple method for the consistent measurement of reaction rates in this heterogenous system was designed and used to obtain detailed enzyme kinetic data relating to optimisation of reaction conditions and substrate specificity. The aqueous content of the system was optimised using p-cresol as a substrate. A crude, immobilised extract of Agaricus bisporus was used to hydroxylate and oxidise a range of selected p-substituted phenolic substrates, yielding, as the sale products, o-quinones. These products were efficiently reduced to catechols by extracting the reaction mixtures with aqueous ascorbic acid solution. The biocatalytic system was also successfully utilised to produce L-DOPA, the drug used to treat Parkinson's disease, from L-acetyl tyrosine ethyl ester (ATEE). Michaelis-Menten kinetics were used to obtain apparent Km and V values with respect to the selected phenolic substrates, and the kinetic parameters obtained were found to correlate well with the steric requirements of the substrates and with their hydrophobicity. In the course of the investigation, a novel ¹H NMR method was used to facilitate measurement of the UV molar absorption coefficients of the o-quinones in reaction mixtures, thus avoiding the necessity to isolate these unstable, water-sensitive products. The biocatalytic system was extended to a continuous process, in which the immobilised enzyme was shown to function successfully in the chloroform medium for several hours, with high conversion rates. Modifications, involving partial purification and the addition of a surfactant, were investigated to determine their effect on the kinetic parameters. The results obtained using partially purified enzyme indicated that the removal of extraneous protein and/or melanoid material lead to a reduced capacity for conversion of sterically demanding substrates. The addition of the anionic detergent, sodium dodecyl sulphate (SOS), enhanced the ability of the biocatalyst to bind and oxidise sterically demanding substrates. These effects are attributed to changes in the polar state of groups within the protein binding pocket, which result in altered flexibility and hydrophobicity. Computer modelling of several biomimetic dinuclear copper complexes also indicated the importance of flexibility for effective biocatalysis. Novel binuclear copper (II complexes, containing a flexible biphenyl spacer and imidazole or benzimidazole donors, were prepared and analysed using NMR, UV, AA and cyclic voltammetric techniques. The complexes were also shown, in a detailed kinetic study, to mimic the catecholase activity of polyphenol oxidase by oxidising 3,5-di-tertbutylcatechol, and to catalyse the coupling of the phenolic substrate 2,4-di-tert-butylphenol. However, the complexes were apparently too flexible to react with smaller substrates. These biomimetic complexes provided valuable insights into the nature of the dinuclear copper binding site.
- Full Text:
- Date Issued: 1994
- Authors: Burton, Stephanie Gail
- Date: 1994
- Subjects: Phenol oxidase Polyphenols Oxidases
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4028 , http://hdl.handle.net/10962/d1004088
- Description: Mushroom polyphenol oxidase (EC 1.14.18.1) was investigated to determine its potential for application as a biocatalyst in the synthesis of o-quinones, in organic medium. In order to determine the kinetic properties of the biocatalyst, a system was devised which comprised an immobilised polyphenol oxidase extract, functioning in chloroform. The system was hydrated by the addition of buffer. A simple method for the consistent measurement of reaction rates in this heterogenous system was designed and used to obtain detailed enzyme kinetic data relating to optimisation of reaction conditions and substrate specificity. The aqueous content of the system was optimised using p-cresol as a substrate. A crude, immobilised extract of Agaricus bisporus was used to hydroxylate and oxidise a range of selected p-substituted phenolic substrates, yielding, as the sale products, o-quinones. These products were efficiently reduced to catechols by extracting the reaction mixtures with aqueous ascorbic acid solution. The biocatalytic system was also successfully utilised to produce L-DOPA, the drug used to treat Parkinson's disease, from L-acetyl tyrosine ethyl ester (ATEE). Michaelis-Menten kinetics were used to obtain apparent Km and V values with respect to the selected phenolic substrates, and the kinetic parameters obtained were found to correlate well with the steric requirements of the substrates and with their hydrophobicity. In the course of the investigation, a novel ¹H NMR method was used to facilitate measurement of the UV molar absorption coefficients of the o-quinones in reaction mixtures, thus avoiding the necessity to isolate these unstable, water-sensitive products. The biocatalytic system was extended to a continuous process, in which the immobilised enzyme was shown to function successfully in the chloroform medium for several hours, with high conversion rates. Modifications, involving partial purification and the addition of a surfactant, were investigated to determine their effect on the kinetic parameters. The results obtained using partially purified enzyme indicated that the removal of extraneous protein and/or melanoid material lead to a reduced capacity for conversion of sterically demanding substrates. The addition of the anionic detergent, sodium dodecyl sulphate (SOS), enhanced the ability of the biocatalyst to bind and oxidise sterically demanding substrates. These effects are attributed to changes in the polar state of groups within the protein binding pocket, which result in altered flexibility and hydrophobicity. Computer modelling of several biomimetic dinuclear copper complexes also indicated the importance of flexibility for effective biocatalysis. Novel binuclear copper (II complexes, containing a flexible biphenyl spacer and imidazole or benzimidazole donors, were prepared and analysed using NMR, UV, AA and cyclic voltammetric techniques. The complexes were also shown, in a detailed kinetic study, to mimic the catecholase activity of polyphenol oxidase by oxidising 3,5-di-tertbutylcatechol, and to catalyse the coupling of the phenolic substrate 2,4-di-tert-butylphenol. However, the complexes were apparently too flexible to react with smaller substrates. These biomimetic complexes provided valuable insights into the nature of the dinuclear copper binding site.
- Full Text:
- Date Issued: 1994
Behavioural model debugging in Linda
- Authors: Sewry, David Andrew
- Date: 1994
- Subjects: LINDA (Computer system) Debugging in computer science
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4674 , http://hdl.handle.net/10962/d1006697
- Description: This thesis investigates event-based behavioural model debugging in Linda. A study is presented of the Linda parallel programming paradigm, its amenability to debugging, and a model for debugging Linda programs using Milner's CCS. In support of the construction of expected behaviour models, a Linda program specification language is proposed. A behaviour recognition engine that is based on such specifications is also discussed. It is shown that Linda's distinctive characteristics make it amenable to debugging without the usual problems associated with paraUel debuggers. Furthermore, it is shown that a behavioural model debugger, based on the proposed specification language, effectively exploits the debugging opportunity. The ideas developed in the thesis are demonstrated in an experimental Modula-2 Linda system.
- Full Text:
- Date Issued: 1994
- Authors: Sewry, David Andrew
- Date: 1994
- Subjects: LINDA (Computer system) Debugging in computer science
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4674 , http://hdl.handle.net/10962/d1006697
- Description: This thesis investigates event-based behavioural model debugging in Linda. A study is presented of the Linda parallel programming paradigm, its amenability to debugging, and a model for debugging Linda programs using Milner's CCS. In support of the construction of expected behaviour models, a Linda program specification language is proposed. A behaviour recognition engine that is based on such specifications is also discussed. It is shown that Linda's distinctive characteristics make it amenable to debugging without the usual problems associated with paraUel debuggers. Furthermore, it is shown that a behavioural model debugger, based on the proposed specification language, effectively exploits the debugging opportunity. The ideas developed in the thesis are demonstrated in an experimental Modula-2 Linda system.
- Full Text:
- Date Issued: 1994
Babesia canis : a characterization of five field stocks in Southern Africa
- Authors: Van Heerden, Garth William
- Date: 1994
- Subjects: Babesia canis -- Africa, Southern , Tick-borne diseases -- Africa, Southern , Dogs -- Parasites
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5645 , http://hdl.handle.net/10962/d1005327 , Babesia canis -- Africa, Southern , Tick-borne diseases -- Africa, Southern , Dogs -- Parasites
- Description: This study attempted to characterise 5 field stocks of B. canis, collected from various geographic areas of southern Africa in terms of pathogenicity, immune response, cross resistance and antigenic composition. This was done by means of artificial infection of two to four year old Beagle dogs. Serological tests included indirect fluorescent antibody tests, polyacrylamide gel electrophoresis , Western blotting of B. canis antigen and immune serum transfers. The ZIM1, GHT1 , QTN1 and DBN1 stocks were found to be virulent and the JHB1 stock, which might be a cardiac form of babesiosis, was found to be highly virulent. Immune responses of dogs to primary challenges were poor. A second challenge or relapse was important in the development of a resistant immunity. Heterologous challenges showed that dogs which were immune to the ZIM1, QTN1 and DBN1 stocks were partially immune to the JHB1 stock. The dog that was immune to the GHT1 stock was the only one that was totally resistant to the JHB1 stock. Western blots revealed interstock antigenic variation between the JHB1 and the other four stocks. These differences were, however, not great enough to separate the stocks taxonomically.
- Full Text:
- Date Issued: 1994
- Authors: Van Heerden, Garth William
- Date: 1994
- Subjects: Babesia canis -- Africa, Southern , Tick-borne diseases -- Africa, Southern , Dogs -- Parasites
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5645 , http://hdl.handle.net/10962/d1005327 , Babesia canis -- Africa, Southern , Tick-borne diseases -- Africa, Southern , Dogs -- Parasites
- Description: This study attempted to characterise 5 field stocks of B. canis, collected from various geographic areas of southern Africa in terms of pathogenicity, immune response, cross resistance and antigenic composition. This was done by means of artificial infection of two to four year old Beagle dogs. Serological tests included indirect fluorescent antibody tests, polyacrylamide gel electrophoresis , Western blotting of B. canis antigen and immune serum transfers. The ZIM1, GHT1 , QTN1 and DBN1 stocks were found to be virulent and the JHB1 stock, which might be a cardiac form of babesiosis, was found to be highly virulent. Immune responses of dogs to primary challenges were poor. A second challenge or relapse was important in the development of a resistant immunity. Heterologous challenges showed that dogs which were immune to the ZIM1, QTN1 and DBN1 stocks were partially immune to the JHB1 stock. The dog that was immune to the GHT1 stock was the only one that was totally resistant to the JHB1 stock. Western blots revealed interstock antigenic variation between the JHB1 and the other four stocks. These differences were, however, not great enough to separate the stocks taxonomically.
- Full Text:
- Date Issued: 1994