Aspects of the biology of the infaunal bivalve Mollusc Solen cylindraceus (Hanley) in the Kariega estuary
- De Villiers, Casper Johannes
- Authors: De Villiers, Casper Johannes
- Date: 1990
- Subjects: Mollusks -- South Africa -- Eastern Cape Bivalves -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5639 , http://hdl.handle.net/10962/d1005321
- Description: Solen cylindraceus is an infaunal filter-feeding bivalve inhabiting the intertidal mud banks of many southern African estuaries. It is particularly abundant in the Kariega estuary (33°41'S; 26°42'E) where it reaches densities of 400m⁻² (192g shell-free dry wt. m⁻²). The Kariega is a permanently open, marine dominated estuary about 18km in length, and S. cylindraceus is most abundant in its middle and upper reaches. Some physical characteristics of the estuary (temperature, salinity, sediment and water turbidity) are described, and the possible role of these factors in determining the density and distribution of S. cylindraceus within the Kariega estuary, is discussed. The structure of the alimentary system, gills and labial palps of S. cylintfraceus is described, all of which showed no major variation from the "typical" eulamellibranchiate form. Solen cylintfraceus was found to be a euryhaline osmoconformer with a salinity tolerance range of 15-65%. When animals were removed from their burrows, osmotic equilibration of the haemolymph was rapid (1-2 hours). By contrast, in animals left undisturbed in their burrows, osmotic equilibration was retarded (72-204 hours). It is suggested that the observed decrease in the rate of change of haemolymph osmolarity for animals in their burrows is linked to the stability of the interstitial salinity. A temperature tolerance range of 5-44°C was determined for S. cylintfraceus (in situ), in which prolonged exposure to 5°C and 40-45°C (12-36 hours respectively) resulted in a decreased burrowing ability, coma and death. Animal burrowing responses were not affected by temperatures in the range 15-35°C. Field experiments were carried out over several tidal cycles, in which the measurement of crystalline style volume was used as a means of assessing extracellular digestive activity. No major variation in style volume was recorded and it appeared that S. cylindraceus did not exhibit any cyclical pattern of style dissolution and regeneration. It is suggested that S. cylindraceus feeds continuously from the water column during high tide and possibly within its burrow, at or below the water table, during low tide. At a suspensoid concentration of 5Omg l⁻¹, S. cylindraceus was found to filter water almost continuously (90-95% of the time). Time spent filtering dropped to 68% at 100mg l⁻¹ and 32% at 500mg l⁻¹. Filtration rates for summer collected animals (25°C) were 22.86 ± 4.36ml min.⁻¹, some 3ml min.⁻¹ greater than that recorded for winter (16°C) collected animals. Filtration rate may be expressed as a function of shell length by the equations: y=0.247x¹̇⁰⁶⁶ (winter) and y=0.758x⁰̇⁸²⁶ (summer). Solen cylindraceus was capable of acclimating its filtration rate to both high and low temperatures under laboratory conditions. Filtration rate exhibited a thermal optimum in the range 15-35°C, declining at higher and lower temperatures. Q₁₀ values of filtration decreased rapidly from greater than 4 to less than 2, when the thermal optimum was reached. Maximum rates generally occurred at approximately 5°C above the temperature to which the animal had been acclimated. Optimal filtration rates (19-23ml min.⁻¹) were recorded in the salinity range 15-45%. When subjected to abrupt changes in salinity, filtration rates were immediately depressed. The extent and duration of these decreased filtration rates were dependent upon the magnitude and direction of salinity change, and were always less in animals exposed to hyper- than hyposaline conditions. Animals exposed to increased temperature and simultaneous elevated or unchanged salinity, showed a slight increase in filtration rate followed by rapid acclimation. A decrease in both temperature and salinity resulted in an initial decrease in filtration rate and a longer acclimation period. The ability of S. cylindraceus to acclimate fully within a wide temperature and salinity range, and to filter maximally in hypersaline conditions may, in part, explain its unusually high abundance in the Kariega estuary, despite it being close to the southernmost limit of the animal's geographical distribution. No significant difference in flItration rate was recorded at suspensoid concentrations of 5-100mg 1⁻¹. However, at 250 and 500mg l⁻¹ filtration rates decreased significantly, and coincided with increased levels of pseudofaecal production. Solen cylindraceus retained particles down to 2.5-3.0µm with great efficiency (ca. 60-90% efficiency). Below this particle size, retention efficiency decreased rapidly and a net production of particles was recorded below 1.51µm. Particle retention was independent of temperature (15 and 25°C) and salinity (15 and 35%). Use was made of stable carbon isotope analyses (¹³C/¹²C ratios) in an attempt to determine the important food sources of S. cylindraceus within the Kariega estuary. The results obtained demonstrated an enrichment in δ¹³ values for S. cylindraceus from the upper (-27.9%) to the middle (-25%c) and lower (-21.6%o ) reaches of the estuary, with no seasonal variation apparent. The bivalve was substantially more depleted in ¹³C relative to the dominant aquatic macrophytes Zostera capensis (-9.1 to -15.6%o) and Spartina maritima (-12.5%o). The use of δ¹³ alone, however, to unequivocally "pin point" specific food sources of a filter feeder in a predominantly detritus based food web, is limited. It is suggested that in the Kariega estuary, riparian litter and other terrestrially derived vegetation contribute to the carbon pool. A possible contribution of ¹³C depleted food sources via chemoautotrophic and/or anaerobic pathways, to the diet of S. cylindraceus, is suggested.
- Full Text:
- Date Issued: 1990
- Authors: De Villiers, Casper Johannes
- Date: 1990
- Subjects: Mollusks -- South Africa -- Eastern Cape Bivalves -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5639 , http://hdl.handle.net/10962/d1005321
- Description: Solen cylindraceus is an infaunal filter-feeding bivalve inhabiting the intertidal mud banks of many southern African estuaries. It is particularly abundant in the Kariega estuary (33°41'S; 26°42'E) where it reaches densities of 400m⁻² (192g shell-free dry wt. m⁻²). The Kariega is a permanently open, marine dominated estuary about 18km in length, and S. cylindraceus is most abundant in its middle and upper reaches. Some physical characteristics of the estuary (temperature, salinity, sediment and water turbidity) are described, and the possible role of these factors in determining the density and distribution of S. cylindraceus within the Kariega estuary, is discussed. The structure of the alimentary system, gills and labial palps of S. cylintfraceus is described, all of which showed no major variation from the "typical" eulamellibranchiate form. Solen cylintfraceus was found to be a euryhaline osmoconformer with a salinity tolerance range of 15-65%. When animals were removed from their burrows, osmotic equilibration of the haemolymph was rapid (1-2 hours). By contrast, in animals left undisturbed in their burrows, osmotic equilibration was retarded (72-204 hours). It is suggested that the observed decrease in the rate of change of haemolymph osmolarity for animals in their burrows is linked to the stability of the interstitial salinity. A temperature tolerance range of 5-44°C was determined for S. cylintfraceus (in situ), in which prolonged exposure to 5°C and 40-45°C (12-36 hours respectively) resulted in a decreased burrowing ability, coma and death. Animal burrowing responses were not affected by temperatures in the range 15-35°C. Field experiments were carried out over several tidal cycles, in which the measurement of crystalline style volume was used as a means of assessing extracellular digestive activity. No major variation in style volume was recorded and it appeared that S. cylindraceus did not exhibit any cyclical pattern of style dissolution and regeneration. It is suggested that S. cylindraceus feeds continuously from the water column during high tide and possibly within its burrow, at or below the water table, during low tide. At a suspensoid concentration of 5Omg l⁻¹, S. cylindraceus was found to filter water almost continuously (90-95% of the time). Time spent filtering dropped to 68% at 100mg l⁻¹ and 32% at 500mg l⁻¹. Filtration rates for summer collected animals (25°C) were 22.86 ± 4.36ml min.⁻¹, some 3ml min.⁻¹ greater than that recorded for winter (16°C) collected animals. Filtration rate may be expressed as a function of shell length by the equations: y=0.247x¹̇⁰⁶⁶ (winter) and y=0.758x⁰̇⁸²⁶ (summer). Solen cylindraceus was capable of acclimating its filtration rate to both high and low temperatures under laboratory conditions. Filtration rate exhibited a thermal optimum in the range 15-35°C, declining at higher and lower temperatures. Q₁₀ values of filtration decreased rapidly from greater than 4 to less than 2, when the thermal optimum was reached. Maximum rates generally occurred at approximately 5°C above the temperature to which the animal had been acclimated. Optimal filtration rates (19-23ml min.⁻¹) were recorded in the salinity range 15-45%. When subjected to abrupt changes in salinity, filtration rates were immediately depressed. The extent and duration of these decreased filtration rates were dependent upon the magnitude and direction of salinity change, and were always less in animals exposed to hyper- than hyposaline conditions. Animals exposed to increased temperature and simultaneous elevated or unchanged salinity, showed a slight increase in filtration rate followed by rapid acclimation. A decrease in both temperature and salinity resulted in an initial decrease in filtration rate and a longer acclimation period. The ability of S. cylindraceus to acclimate fully within a wide temperature and salinity range, and to filter maximally in hypersaline conditions may, in part, explain its unusually high abundance in the Kariega estuary, despite it being close to the southernmost limit of the animal's geographical distribution. No significant difference in flItration rate was recorded at suspensoid concentrations of 5-100mg 1⁻¹. However, at 250 and 500mg l⁻¹ filtration rates decreased significantly, and coincided with increased levels of pseudofaecal production. Solen cylindraceus retained particles down to 2.5-3.0µm with great efficiency (ca. 60-90% efficiency). Below this particle size, retention efficiency decreased rapidly and a net production of particles was recorded below 1.51µm. Particle retention was independent of temperature (15 and 25°C) and salinity (15 and 35%). Use was made of stable carbon isotope analyses (¹³C/¹²C ratios) in an attempt to determine the important food sources of S. cylindraceus within the Kariega estuary. The results obtained demonstrated an enrichment in δ¹³ values for S. cylindraceus from the upper (-27.9%) to the middle (-25%c) and lower (-21.6%o ) reaches of the estuary, with no seasonal variation apparent. The bivalve was substantially more depleted in ¹³C relative to the dominant aquatic macrophytes Zostera capensis (-9.1 to -15.6%o) and Spartina maritima (-12.5%o). The use of δ¹³ alone, however, to unequivocally "pin point" specific food sources of a filter feeder in a predominantly detritus based food web, is limited. It is suggested that in the Kariega estuary, riparian litter and other terrestrially derived vegetation contribute to the carbon pool. A possible contribution of ¹³C depleted food sources via chemoautotrophic and/or anaerobic pathways, to the diet of S. cylindraceus, is suggested.
- Full Text:
- Date Issued: 1990
Aspects of the nutritional physiology and dietary requirements of juvenile and adult sharptooth catfish, Clarias Gariepinus (Pisces : clariidae)
- Authors: Uys, Wynand
- Date: 1990
- Subjects: Clariidae Catfishes Catfishes -- Nutrition-requirements Clarias
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5225 , http://hdl.handle.net/10962/d1005068
- Description: Past and current research on the biology and culture of the sharptooth catfish (Clarias gariepinus) has stimulated the development of its commercial production. At the inception of this project in 1985, it was decided that the development of an optimal dry feed was the most important step in developing a more complete culture technology for the species. The objectives of the project were, therefore, to investigate aspects of the nutritional physiology and dietary requirements of the species to provide the necessary information for the formulation of optimum economical feeds. A review of the natural feeding biology of the species provided valuable information with regard to its food preferences. From this information, and by estimating the nutritional composition of its preferred natural diet, it could be concluded that the animal requires a relatively high dietary protein content. This conclusion was substantiated by studies of the functional morphology of the digestive system (gross and fine structure). The characteristics of the digestive system and external anatomy were found to be typical of an opportunistic, omnivorous predator. The ontogenetic development of the digestive system is relatively fast, and enables the utilization of a variety of diets efficiently from an early stage. Since the ability of an animal to digest a given substance is predominantly dependent on the presence of appropriate enzymes the quantification and characterization of C. gariepinus digestive enzyme activities were investigated on an experimental basis. This work revealed that the animal has relatively high levels of digestive enzyme activities, and that its proteolytic enzyme activities correspond with those of other carnivorous fishes, while its starch digesting abilities correspond with those of specialized herbivores. Also, the high levels of lysozyme and alkaline phosphatase indicate an adaptation to detritivory, making this fish a truly opportunistic omnivore. Evidence was found to suggest that sharptooth catfish are able to re-absorb secreted digestive enzymes in the posterior section of its intestinal tract. It was shown that digestive enzyme activities were induced by food intake, and that no inherent rhythmicity in digestive activities seemed to occur. The development of digestive enzyme systems in the early life history of this animal was found to be also extremely rapid (complete within 10-16 days after hatching). It was also shown that artificial dry feed stimulates higher levels of digestive enzyme activities in larvae and juveniles than natural food. Although increased cellulase activity was found in larvae and juveniles that were fed on live zooplankton, the relative contribution of exogenous prey enzymes to protein digestion could not be ascertained. Specific nutritional requirements were investigated by means of feeding trials. The results of these trials confirmed the above indications regarding the dietary requirements of sharptooth catfish. It was concluded that for optimal growth and production performance, this animal requires a dietary protein content of 40-42%, a dietary lipid content of 10-12% and that diets should contain 14-16 kJ/g digestible energy. The optimum protein-to-energy ratio was found to be 26-29mg protein per kJ of digestible energy. Dietary requirements are evidently the same for juveniles and adults, except that younger fish require higher relative feeding levels. Finally, practical feed formulations were evaluated in terms of their economic feasibility. The results of these trials are presented along with recommendations on the formulation of commercial feeds for C. gariepinus. A computer program with which to implement least cost feed formulation by means of linear programming is provided.
- Full Text:
- Date Issued: 1990
- Authors: Uys, Wynand
- Date: 1990
- Subjects: Clariidae Catfishes Catfishes -- Nutrition-requirements Clarias
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5225 , http://hdl.handle.net/10962/d1005068
- Description: Past and current research on the biology and culture of the sharptooth catfish (Clarias gariepinus) has stimulated the development of its commercial production. At the inception of this project in 1985, it was decided that the development of an optimal dry feed was the most important step in developing a more complete culture technology for the species. The objectives of the project were, therefore, to investigate aspects of the nutritional physiology and dietary requirements of the species to provide the necessary information for the formulation of optimum economical feeds. A review of the natural feeding biology of the species provided valuable information with regard to its food preferences. From this information, and by estimating the nutritional composition of its preferred natural diet, it could be concluded that the animal requires a relatively high dietary protein content. This conclusion was substantiated by studies of the functional morphology of the digestive system (gross and fine structure). The characteristics of the digestive system and external anatomy were found to be typical of an opportunistic, omnivorous predator. The ontogenetic development of the digestive system is relatively fast, and enables the utilization of a variety of diets efficiently from an early stage. Since the ability of an animal to digest a given substance is predominantly dependent on the presence of appropriate enzymes the quantification and characterization of C. gariepinus digestive enzyme activities were investigated on an experimental basis. This work revealed that the animal has relatively high levels of digestive enzyme activities, and that its proteolytic enzyme activities correspond with those of other carnivorous fishes, while its starch digesting abilities correspond with those of specialized herbivores. Also, the high levels of lysozyme and alkaline phosphatase indicate an adaptation to detritivory, making this fish a truly opportunistic omnivore. Evidence was found to suggest that sharptooth catfish are able to re-absorb secreted digestive enzymes in the posterior section of its intestinal tract. It was shown that digestive enzyme activities were induced by food intake, and that no inherent rhythmicity in digestive activities seemed to occur. The development of digestive enzyme systems in the early life history of this animal was found to be also extremely rapid (complete within 10-16 days after hatching). It was also shown that artificial dry feed stimulates higher levels of digestive enzyme activities in larvae and juveniles than natural food. Although increased cellulase activity was found in larvae and juveniles that were fed on live zooplankton, the relative contribution of exogenous prey enzymes to protein digestion could not be ascertained. Specific nutritional requirements were investigated by means of feeding trials. The results of these trials confirmed the above indications regarding the dietary requirements of sharptooth catfish. It was concluded that for optimal growth and production performance, this animal requires a dietary protein content of 40-42%, a dietary lipid content of 10-12% and that diets should contain 14-16 kJ/g digestible energy. The optimum protein-to-energy ratio was found to be 26-29mg protein per kJ of digestible energy. Dietary requirements are evidently the same for juveniles and adults, except that younger fish require higher relative feeding levels. Finally, practical feed formulations were evaluated in terms of their economic feasibility. The results of these trials are presented along with recommendations on the formulation of commercial feeds for C. gariepinus. A computer program with which to implement least cost feed formulation by means of linear programming is provided.
- Full Text:
- Date Issued: 1990
Between freedom and givenness: (a study of the hermeneutical consequences of the concept of canon for the authority of scripture)
- Authors: Latham, Jonathan Cyril
- Date: 1990
- Subjects: Bible -- Evidences, authority, etc. , Authority -- Religious aspects , Canon (Literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1216 , http://hdl.handle.net/10962/d1001546
- Description: The aim of this thesis is to arrive at an understanding of the authority of scripture that is able to accommodate both a faith perspective and the fruits of the historical-critical approach to the New Testament. Put differently, the aim of this thesis is the pursuit of a specifically christian, faith-promoting, reading of the New Testament whilst still enjoying the benefit, in an as uncompromised a form as possible, of the historical- critical approach. In a sense it may be said that this task, given that the roots of both the historical-critical approach and modern Western culture are deeply imbedded in Rationalism, is equivalent to the basic hermeneutical question of whether it is possible to interpret scripture relevantly from within a cultural web of meaning that does not readily accommodate that embodied in the New Testament. In section one of this dissertation we present a characteristic depiction, based on the historical-critical theory of literature, of the authority of the New Testament. This is followed by a brief assessment that makes explicit why the historical- critical approach is not conducive to the adoption of a faith perspective on these writings. In section two, still and inevitably based on critical foundations, we adopt a perspective that is more sympathetic to faith and that seeks to discover in the concerns evidenced in the canonical process, when traditions about Jesus gradually took on more complex and stable forms, culminating in the canon of the New Testament, guidelines in helping us to deal with the problem with which this study is concerned . In the specific example of the rather ordinary concerns underlying the unusual history of the pericope de adultera (John 7:53-8:11), examined against the background of the interests underlying the canonical process, it becomes clear that christians from the very beginning faced a dilemma not unlike that with which the historical-critical approach confronts us. They had to interpret afresh, and faithfully, the traditions in order to meet the demands of situations that had never been foreseen by earlier tradents. In this respect, therefore, the history of the pericope de adultera presents us with an ongoing struggle to hold in tension the demands of new contexts with the imperative of strict continuity with Jesus. In section three, on the basis of the foundation of the authority of scripture in strict continuity with Jesus combined with the contextual reinterpretation of the tradition, the social sciences are employed. Using the social sciences, it is discovered that the two contradictory approaches that we wish to reconcile form part of two different models for interpreting reality. It is on this basis, and made possible by the common culture underlying these opposing models and by the common contact with an unspecified common core of concrete reality, that a solution is proposed in terms of a complex 'fusion of horizons', promoted by a 'precipitative environment'. In the conclusion our solution is decisively aligned with the concerns evidenced in the canonical process
- Full Text:
- Date Issued: 1990
- Authors: Latham, Jonathan Cyril
- Date: 1990
- Subjects: Bible -- Evidences, authority, etc. , Authority -- Religious aspects , Canon (Literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1216 , http://hdl.handle.net/10962/d1001546
- Description: The aim of this thesis is to arrive at an understanding of the authority of scripture that is able to accommodate both a faith perspective and the fruits of the historical-critical approach to the New Testament. Put differently, the aim of this thesis is the pursuit of a specifically christian, faith-promoting, reading of the New Testament whilst still enjoying the benefit, in an as uncompromised a form as possible, of the historical- critical approach. In a sense it may be said that this task, given that the roots of both the historical-critical approach and modern Western culture are deeply imbedded in Rationalism, is equivalent to the basic hermeneutical question of whether it is possible to interpret scripture relevantly from within a cultural web of meaning that does not readily accommodate that embodied in the New Testament. In section one of this dissertation we present a characteristic depiction, based on the historical-critical theory of literature, of the authority of the New Testament. This is followed by a brief assessment that makes explicit why the historical- critical approach is not conducive to the adoption of a faith perspective on these writings. In section two, still and inevitably based on critical foundations, we adopt a perspective that is more sympathetic to faith and that seeks to discover in the concerns evidenced in the canonical process, when traditions about Jesus gradually took on more complex and stable forms, culminating in the canon of the New Testament, guidelines in helping us to deal with the problem with which this study is concerned . In the specific example of the rather ordinary concerns underlying the unusual history of the pericope de adultera (John 7:53-8:11), examined against the background of the interests underlying the canonical process, it becomes clear that christians from the very beginning faced a dilemma not unlike that with which the historical-critical approach confronts us. They had to interpret afresh, and faithfully, the traditions in order to meet the demands of situations that had never been foreseen by earlier tradents. In this respect, therefore, the history of the pericope de adultera presents us with an ongoing struggle to hold in tension the demands of new contexts with the imperative of strict continuity with Jesus. In section three, on the basis of the foundation of the authority of scripture in strict continuity with Jesus combined with the contextual reinterpretation of the tradition, the social sciences are employed. Using the social sciences, it is discovered that the two contradictory approaches that we wish to reconcile form part of two different models for interpreting reality. It is on this basis, and made possible by the common culture underlying these opposing models and by the common contact with an unspecified common core of concrete reality, that a solution is proposed in terms of a complex 'fusion of horizons', promoted by a 'precipitative environment'. In the conclusion our solution is decisively aligned with the concerns evidenced in the canonical process
- Full Text:
- Date Issued: 1990
Chemical and spectroscopic studies of the capsular polysaccharides of some klebsiella and escherichia coli serotypes
- Authors: Stanley, Shawn Mark Ross
- Date: 1990
- Subjects: Polysaccharides , Klebsiella , Escherichia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3736 , http://hdl.handle.net/10962/d1001525
- Description: The work described in this thesis forms part of an international programme concerned with the structure elucidation of the capsular antigens of some Enterobacteriaceae. Many of the Klebsiella and some of the Escherichia coli are pathogenic to man and, hence, they are of interest. The virulence of bacteria is a multifactorial phenomenon, in which characteristic traits of bacteria and their hosts play comparable and complementary roles. It is accepted that pathogens are more virulent when encapsulated, because, nearly all disease causing bacteria have a capsule when freshly isolated from the host. This increase in pathogenicity is related, in part, to the capsular polysaccharides' ability to avoid or attenuate the host defence mechanisms. In the majority of cases the protective aspects of the capsule are overcome in the latter stages of infection when the formation of specific antibodies by the host has occurred. However there are situations in which an immune state of the infected host is virtually never reached, and susceptiblity to the infecting bacteria is maintained even in the advanced stage of an infection. Explanation of this phenomenon becomes possible by analysing the structure of the polysaccharides. The inability of the host to raise an immune response to the capsule may be because the structure of the polysaccharide is similar or identical to the host's carbohydrates. The serological and pathogenic relatedness of encapsulated E. coli and Klebsiella, to the encapsulated strains of other genera, is based on structural identity or similarity of the respective capsules. Capsular polysaccharides are analysed by both chemical and instrumental methods, and, at present, nuclear magnetic resonance spectroscopy is the most important analytical technique
- Full Text:
- Date Issued: 1990
- Authors: Stanley, Shawn Mark Ross
- Date: 1990
- Subjects: Polysaccharides , Klebsiella , Escherichia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3736 , http://hdl.handle.net/10962/d1001525
- Description: The work described in this thesis forms part of an international programme concerned with the structure elucidation of the capsular antigens of some Enterobacteriaceae. Many of the Klebsiella and some of the Escherichia coli are pathogenic to man and, hence, they are of interest. The virulence of bacteria is a multifactorial phenomenon, in which characteristic traits of bacteria and their hosts play comparable and complementary roles. It is accepted that pathogens are more virulent when encapsulated, because, nearly all disease causing bacteria have a capsule when freshly isolated from the host. This increase in pathogenicity is related, in part, to the capsular polysaccharides' ability to avoid or attenuate the host defence mechanisms. In the majority of cases the protective aspects of the capsule are overcome in the latter stages of infection when the formation of specific antibodies by the host has occurred. However there are situations in which an immune state of the infected host is virtually never reached, and susceptiblity to the infecting bacteria is maintained even in the advanced stage of an infection. Explanation of this phenomenon becomes possible by analysing the structure of the polysaccharides. The inability of the host to raise an immune response to the capsule may be because the structure of the polysaccharide is similar or identical to the host's carbohydrates. The serological and pathogenic relatedness of encapsulated E. coli and Klebsiella, to the encapsulated strains of other genera, is based on structural identity or similarity of the respective capsules. Capsular polysaccharides are analysed by both chemical and instrumental methods, and, at present, nuclear magnetic resonance spectroscopy is the most important analytical technique
- Full Text:
- Date Issued: 1990
Dealing with distress: a medical anthropological analysis of the search for health in a rural Transkeian village
- Authors: Simon, Christian Michael
- Date: 1990
- Subjects: Medical care -- South Africa -- Transkei -- Jotelo , Poor -- Health and hygiene -- South Africa -- Transkei , Transkei (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2082 , http://hdl.handle.net/10962/d1001599
- Description: This study aims to characterize and understand the search for health in a rural Transkeian community. It begins with the observation that the people of Jotelo have to negotiate considerable hardships in their daily lives. These hardships include the impact of malnutrition, undernourishment and a wide range of diseases like tuberculosis, typhoid and gastro-enteritis. To survive ill-health, people develop numerous practical strategies. Most significantly, they attempt to maximise availalble resources, like cash, their relations with others and local medical facilities. Hence the study attempts to characterize how and why patients select various kinds of therapy in their search for health. By focusing on patients' recourses to treatment, the study reveals that the search for health is as much a personal experience as it is a social and economic one. This idea is developed in an analysis of the links betw'een work, illness and social reproduction. The point which emerges from this discussion captures the central theme of the study: the search for health is a profoundly personal, social and economic experience. This notion is strengthened by an examination of the historical and contemporary nature of local health and health care. It is observed that health and health care is intimately linked to the local and wider political economy. This not only serves to contextualise the discussion on patients' actual experiences, but points to the fact that these experiences are part of wider processes. By depicting the search for health in this way, the study hopes to have illustrated what people do in times of illness and why. Yet it also claims to have gone beyond such a depiction. By abstracting from its findings, it aims to conclude that the search for health is not merely caused by various local and wider processes, to which it has referred. In other words, it hopes to avoid a deterministic view of patients' experiences in times of distress. Instead, it is argued that the search for health is ultimately an integral part of the local and wider economic and political environment
- Full Text:
- Date Issued: 1990
- Authors: Simon, Christian Michael
- Date: 1990
- Subjects: Medical care -- South Africa -- Transkei -- Jotelo , Poor -- Health and hygiene -- South Africa -- Transkei , Transkei (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2082 , http://hdl.handle.net/10962/d1001599
- Description: This study aims to characterize and understand the search for health in a rural Transkeian community. It begins with the observation that the people of Jotelo have to negotiate considerable hardships in their daily lives. These hardships include the impact of malnutrition, undernourishment and a wide range of diseases like tuberculosis, typhoid and gastro-enteritis. To survive ill-health, people develop numerous practical strategies. Most significantly, they attempt to maximise availalble resources, like cash, their relations with others and local medical facilities. Hence the study attempts to characterize how and why patients select various kinds of therapy in their search for health. By focusing on patients' recourses to treatment, the study reveals that the search for health is as much a personal experience as it is a social and economic one. This idea is developed in an analysis of the links betw'een work, illness and social reproduction. The point which emerges from this discussion captures the central theme of the study: the search for health is a profoundly personal, social and economic experience. This notion is strengthened by an examination of the historical and contemporary nature of local health and health care. It is observed that health and health care is intimately linked to the local and wider political economy. This not only serves to contextualise the discussion on patients' actual experiences, but points to the fact that these experiences are part of wider processes. By depicting the search for health in this way, the study hopes to have illustrated what people do in times of illness and why. Yet it also claims to have gone beyond such a depiction. By abstracting from its findings, it aims to conclude that the search for health is not merely caused by various local and wider processes, to which it has referred. In other words, it hopes to avoid a deterministic view of patients' experiences in times of distress. Instead, it is argued that the search for health is ultimately an integral part of the local and wider economic and political environment
- Full Text:
- Date Issued: 1990
Die verhouding tussen literêre teorie en kritiek in die Afrikaanse literêre sisteem binne die sg. "nuwe paradigma" aan die hand van gekose figure Marianne de Jong, Joan Hambidge en Gerrit Olivier
- Mudzanani, Nndanduleni Bethuel
- Authors: Mudzanani, Nndanduleni Bethuel
- Date: 1990
- Subjects: Olivier, Gerrit, 1954- , Hambidge, Joan, 1956- , De Jong, Marianne , Afrikaans literature -- History and criticism , Afrikaans literature -- Criticism and interpretation
- Language: Afrikaans
- Type: Thesis , Masters , MA
- Identifier: vital:3599 , http://hdl.handle.net/10962/d1002174 , Olivier, Gerrit, 1954- , Hambidge, Joan, 1956- , De Jong, Marianne , Afrikaans literature -- History and criticism , Afrikaans literature -- Criticism and interpretation
- Description: Currently, in the period of Poststructualism literature is widely approached as a cultural and social phenomenon and the aims of literary studies as the illuminating of social codes, ideology etc. embedded in literature. This study evaluates the contribution of specific critics working within the so-called "New paradigm". The concept "New paradigm" is used as an umbrella term covering a number of distinct developments, referring to literature as a system of literary "actions" rather than as a canon of books. In recent years several Afrikaans critics have embraced or adapted current theories in the domains of Deconstruction, Ideology Criticism, Literary, Sociology, Recepticm Aesthetics, Semiotics and Feminism. This study explores and evaluates the application of such theoretical paradigms to their work in the field of practical criticism. This study also explores the relationship between current theories of literature and their antecedents. The notion of current literary theory and practice not only as a broadening of scope and content of the notion of the "literary" but on the other hand as a liberation of theory and practice from an over-deterministic thrust (i.e. the approach of literature as no more than a set of social documents) is also evaluated in this study. A twofold aim of this study can thus be defined: a. to determine the extent to which the shift from the "old" to "new" theories was made necessary by the developing literary and social scene; b. to examine the links beween theory and practice in the work of specific, key figures in Afrikaans. Is it possible for theory and practice to be separated? Is there an important consistence in the relationship between the two in the work of the figures chosen?
- Full Text:
- Date Issued: 1990
- Authors: Mudzanani, Nndanduleni Bethuel
- Date: 1990
- Subjects: Olivier, Gerrit, 1954- , Hambidge, Joan, 1956- , De Jong, Marianne , Afrikaans literature -- History and criticism , Afrikaans literature -- Criticism and interpretation
- Language: Afrikaans
- Type: Thesis , Masters , MA
- Identifier: vital:3599 , http://hdl.handle.net/10962/d1002174 , Olivier, Gerrit, 1954- , Hambidge, Joan, 1956- , De Jong, Marianne , Afrikaans literature -- History and criticism , Afrikaans literature -- Criticism and interpretation
- Description: Currently, in the period of Poststructualism literature is widely approached as a cultural and social phenomenon and the aims of literary studies as the illuminating of social codes, ideology etc. embedded in literature. This study evaluates the contribution of specific critics working within the so-called "New paradigm". The concept "New paradigm" is used as an umbrella term covering a number of distinct developments, referring to literature as a system of literary "actions" rather than as a canon of books. In recent years several Afrikaans critics have embraced or adapted current theories in the domains of Deconstruction, Ideology Criticism, Literary, Sociology, Recepticm Aesthetics, Semiotics and Feminism. This study explores and evaluates the application of such theoretical paradigms to their work in the field of practical criticism. This study also explores the relationship between current theories of literature and their antecedents. The notion of current literary theory and practice not only as a broadening of scope and content of the notion of the "literary" but on the other hand as a liberation of theory and practice from an over-deterministic thrust (i.e. the approach of literature as no more than a set of social documents) is also evaluated in this study. A twofold aim of this study can thus be defined: a. to determine the extent to which the shift from the "old" to "new" theories was made necessary by the developing literary and social scene; b. to examine the links beween theory and practice in the work of specific, key figures in Afrikaans. Is it possible for theory and practice to be separated? Is there an important consistence in the relationship between the two in the work of the figures chosen?
- Full Text:
- Date Issued: 1990
Enrichment strategies for gifted English first language (HG) pupils at the senior secondary level : a critical evaluation of a programme implemented at Grey Boys' High School, Port Elizabeth, 1986-1988
- Authors: Cunningham, Gregory Mark
- Date: 1990
- Subjects: English language -- Study and teaching (Secondary) -- South Africa -- Eastern Cape Gifted children -- Education (Secondary) -- South Africa -- Eastern Cape Gifted children -- Education -- Research
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1510 , http://hdl.handle.net/10962/d1003392
- Description: Programmes developed specifically for the gifted and talented pupil are not a novel idea. Yet, by comparison, the history of gifted education is a brief one. Highly gifted and talented pupils often have difficulty being challenged in a conventional classroom situation. Since classroom instruction is usually designed for the benefit of pupils who function at the level of the majority of their peer age-group, this teaching, no matter how well done, may not be appropriate for the extremely gifted pupil whose abilities differ greatly from this group. Even special programmes for gifted and talented students may be designed for a broad group of gifted students and may not meet the specific needs of the gifted child, especially ones with a special intellectual talent. While it is important to bear aspects such as the characteristics of giftedness and the attributes of the talented individual in mind, the basis of this dissertation examines what enrichment and acceleration strategies may be utilised by the English First Language (HG) teacher when presented with a preselected group of pupils who are gifted in English, utilising a composite gifted educational model as a mechanism for the development of this specific programme.
- Full Text:
- Date Issued: 1990
- Authors: Cunningham, Gregory Mark
- Date: 1990
- Subjects: English language -- Study and teaching (Secondary) -- South Africa -- Eastern Cape Gifted children -- Education (Secondary) -- South Africa -- Eastern Cape Gifted children -- Education -- Research
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1510 , http://hdl.handle.net/10962/d1003392
- Description: Programmes developed specifically for the gifted and talented pupil are not a novel idea. Yet, by comparison, the history of gifted education is a brief one. Highly gifted and talented pupils often have difficulty being challenged in a conventional classroom situation. Since classroom instruction is usually designed for the benefit of pupils who function at the level of the majority of their peer age-group, this teaching, no matter how well done, may not be appropriate for the extremely gifted pupil whose abilities differ greatly from this group. Even special programmes for gifted and talented students may be designed for a broad group of gifted students and may not meet the specific needs of the gifted child, especially ones with a special intellectual talent. While it is important to bear aspects such as the characteristics of giftedness and the attributes of the talented individual in mind, the basis of this dissertation examines what enrichment and acceleration strategies may be utilised by the English First Language (HG) teacher when presented with a preselected group of pupils who are gifted in English, utilising a composite gifted educational model as a mechanism for the development of this specific programme.
- Full Text:
- Date Issued: 1990
Essential fatty acids and ascorbic acid- interactions and effects on melanoma growth
- Authors: Gardiner, Neil Stockenstrom
- Date: 1990
- Subjects: Fatty acids , Melanoma , Mice -- Diseases
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4549 , http://hdl.handle.net/10962/d1018230
- Description: The present study was carried out to determine the effects and possible mechanisms of action of the essential fatty acids (EFAs) (linoleic acid (LA), gamma-linolenic acid (GLA) and arachidonic acid (AA)) and ascorbic acid (Asc) on BL6 murine melanoma growth in cell culture and in mice. Interactions between the nutrients in influencing melanoma growth as well as possible mechanisms of the interactions were also examined in the above systems. Cell culture studies revealed that all three EFAs (0-SOμg/ml) and Asc (0-200μg/ml) significantly inhibited melanoma growth at the concentrations used. The EF As were also found to significantly inhibit growth, although to a lesser extent than BL6 cells, of monkey kidney (LLCMK) cells which were used as a non-malignant control cell line. Asc in contrast was found not to inhibit growth of these cells. Supplementation of Asc (lOO)μg/ml) to EFA containing (0-50μg/ml) medium was found to significantly increase inhibition of cell growth in both cell lines, and in the BL6 cells in particular, after taking into account the growth inhibitory effects of Asc in the absence of EFAs. The mechanism of cell growth inhibition by the EF As appeared to involve lipid peroxidation but not enhanced prostaglandin (PG) or leukotriene (LT) synthesis. While Asc was found to increase both lipid peroxidation and PG synthesis in the cells, these mechanisms and enhanced LT synthesis did not appear to have played a role in the inhibition of cell growth by Asc or in the growth inhibitory interaction between Asc and the EF As. In vivo studies revealed that diets containing essential or polyunsaturated fatty acids (EFAs/PUFAs) in the form of vegetable oils, and in particular GLA in the form of evening primrose oil, significantly promoted melanoma growth in mice when compared with an EFA/PUFA free diet containing predominantly saturated fats (SF). Supplementary dietary Asc in contrast was found to significantly inhibit melanoma growth in mice fed EFA/PUFA, and in particular GLA, containing diets but not in mice fed SF cont~g diets. This result appears to indicate the occurrence of an interaction between the two nutrients. Ul The mechanism of tumour promotion by the EP As/PUP As did not appear to have involved enhanced PG or LT synthesis or lipid peroxidation. Since dietary EPA/PUPA manipulation was found to significantly alter the EPA content of tissues, including the melanomas, the mechanism of tumour promotion may have involved changes in the EPA composition of the tumour cells. While supplementary Asc was found to significantly increase the Asc content of certain tissues, including the melanomas, which may have played a role in tumour growth inhibition by Asc, it was found not to affect the EPA content of tissues. Enhanced PG or LT synthesis and lipid perox:idation did not appear to have been involved in the tumour growth inhibitory interaction between Asc and the EP As/PUP As. THe activity of the enzyme delta-6-desaturase, a key enzyme in EF A metabolism which catalyses the desaturation of LA to GLA, and the influence of Asc on activity of the enzyme were also examined. The cultured cells, and BL6 cells in particular, were found to contain significant activity of the enzyme. Whereas murine liver microsomal fractions were found to contain delta-6-desaturase activity, microsomes from melanomas grown in mice were found to lack activity of the enzyme. The significant tumour promoting effects of the GLA containing EPO diet may have been the result of the lack of delta-6-desaturase activity in tumour cells grown in mice. Asc was found to stimulate activity of the enzyme in cultured BL6 cells but not in LLCM.K cells, while dietary Asc and EF A/PUP A manipulation did not influence activity of the enzyme in microsomal fractions. This study has confirmed previous reports of the in vivo tumour promoting effects of dietary EP As/PUP As and the tumour growth inhibitory effects of Asc. The in vitro cell growth inhibitory effects of Asc and the EP As also confirm the results of previous reports. Previous studies investigating possible interactions between Asc and EP As/PUP As in influencing tumour cell growth could not be located in the relevant literature. This study may therefore be one of the first investigations of any such interaction between these nutrients in tumour cells. While this study was not able to identify the mechanisms involved in the different tumour promoting or tumour growth inhibitory effects of the two nutrients in the two systems, it did eliminate a number of potential mechanisms. The results of this study also emphasise the difficulty of attempting to compare the results of in vitro and in vivo studies.
- Full Text:
- Date Issued: 1990
- Authors: Gardiner, Neil Stockenstrom
- Date: 1990
- Subjects: Fatty acids , Melanoma , Mice -- Diseases
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4549 , http://hdl.handle.net/10962/d1018230
- Description: The present study was carried out to determine the effects and possible mechanisms of action of the essential fatty acids (EFAs) (linoleic acid (LA), gamma-linolenic acid (GLA) and arachidonic acid (AA)) and ascorbic acid (Asc) on BL6 murine melanoma growth in cell culture and in mice. Interactions between the nutrients in influencing melanoma growth as well as possible mechanisms of the interactions were also examined in the above systems. Cell culture studies revealed that all three EFAs (0-SOμg/ml) and Asc (0-200μg/ml) significantly inhibited melanoma growth at the concentrations used. The EF As were also found to significantly inhibit growth, although to a lesser extent than BL6 cells, of monkey kidney (LLCMK) cells which were used as a non-malignant control cell line. Asc in contrast was found not to inhibit growth of these cells. Supplementation of Asc (lOO)μg/ml) to EFA containing (0-50μg/ml) medium was found to significantly increase inhibition of cell growth in both cell lines, and in the BL6 cells in particular, after taking into account the growth inhibitory effects of Asc in the absence of EFAs. The mechanism of cell growth inhibition by the EF As appeared to involve lipid peroxidation but not enhanced prostaglandin (PG) or leukotriene (LT) synthesis. While Asc was found to increase both lipid peroxidation and PG synthesis in the cells, these mechanisms and enhanced LT synthesis did not appear to have played a role in the inhibition of cell growth by Asc or in the growth inhibitory interaction between Asc and the EF As. In vivo studies revealed that diets containing essential or polyunsaturated fatty acids (EFAs/PUFAs) in the form of vegetable oils, and in particular GLA in the form of evening primrose oil, significantly promoted melanoma growth in mice when compared with an EFA/PUFA free diet containing predominantly saturated fats (SF). Supplementary dietary Asc in contrast was found to significantly inhibit melanoma growth in mice fed EFA/PUFA, and in particular GLA, containing diets but not in mice fed SF cont~g diets. This result appears to indicate the occurrence of an interaction between the two nutrients. Ul The mechanism of tumour promotion by the EP As/PUP As did not appear to have involved enhanced PG or LT synthesis or lipid peroxidation. Since dietary EPA/PUPA manipulation was found to significantly alter the EPA content of tissues, including the melanomas, the mechanism of tumour promotion may have involved changes in the EPA composition of the tumour cells. While supplementary Asc was found to significantly increase the Asc content of certain tissues, including the melanomas, which may have played a role in tumour growth inhibition by Asc, it was found not to affect the EPA content of tissues. Enhanced PG or LT synthesis and lipid perox:idation did not appear to have been involved in the tumour growth inhibitory interaction between Asc and the EP As/PUP As. THe activity of the enzyme delta-6-desaturase, a key enzyme in EF A metabolism which catalyses the desaturation of LA to GLA, and the influence of Asc on activity of the enzyme were also examined. The cultured cells, and BL6 cells in particular, were found to contain significant activity of the enzyme. Whereas murine liver microsomal fractions were found to contain delta-6-desaturase activity, microsomes from melanomas grown in mice were found to lack activity of the enzyme. The significant tumour promoting effects of the GLA containing EPO diet may have been the result of the lack of delta-6-desaturase activity in tumour cells grown in mice. Asc was found to stimulate activity of the enzyme in cultured BL6 cells but not in LLCM.K cells, while dietary Asc and EF A/PUP A manipulation did not influence activity of the enzyme in microsomal fractions. This study has confirmed previous reports of the in vivo tumour promoting effects of dietary EP As/PUP As and the tumour growth inhibitory effects of Asc. The in vitro cell growth inhibitory effects of Asc and the EP As also confirm the results of previous reports. Previous studies investigating possible interactions between Asc and EP As/PUP As in influencing tumour cell growth could not be located in the relevant literature. This study may therefore be one of the first investigations of any such interaction between these nutrients in tumour cells. While this study was not able to identify the mechanisms involved in the different tumour promoting or tumour growth inhibitory effects of the two nutrients in the two systems, it did eliminate a number of potential mechanisms. The results of this study also emphasise the difficulty of attempting to compare the results of in vitro and in vivo studies.
- Full Text:
- Date Issued: 1990
Household, production and the organisation of cooperative labour in Shixini, Transkei
- Authors: Heron, Gavin Stewart
- Date: 1990
- Subjects: Xhosa (African people) , Agriculture -- South Africa -- Transkei , Agriculture, Cooperative -- South Africa -- Transkei , Cooperative societies -- South Africa -- Transkei
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2109 , http://hdl.handle.net/10962/d1007448 , Xhosa (African people) , Agriculture -- South Africa -- Transkei , Agriculture, Cooperative -- South Africa -- Transkei , Cooperative societies -- South Africa -- Transkei
- Description: Incidences of cooperation in agricultural activity are widespread phenomena in low-income third world communities. Two forms of cooperative labour groupings are identified in Shixini, Transkei . These are the work party and the ploughing company. It is argued that different organisational principles operate in the different cooperative forms. Work parties are based on principles of neighbourhood whi Ie ploughing companies are organised around kinship relationships. Factors which determine the principle of organisation are social values; the wider South African economic system; ecology; reciprocity; the constitution and structure of the household; economic differentiation; and labour demand and supply. The dissertation is divided into five chapters. The first is an overview of the Shixini social, economic and political systems. This chapter discusses the influence of the wider South African politico-economic system on agricultural production; the Shixini!Transkei political context; kinship and its relation to social organisation; and the likely effects of an agricultural 'betterment' scheme on the area. The second chapter is an overview of agricultural production in Shixini. It is found that the most significant determinants of agricultural production is the structure and constitution of the household and the way in which stock is distributed in the community. The third and fourth chapters describe and analyse Xhosa work parties and ploughing companies . Argument is lead as to the reasons for the specific organisational principles operating in each case. The penultimate chapter is an analysis of sacred and secular ritual. It is argued that both ritual forms reveal cooperative principles of organisation. Secular ritual dramatises the organisation of work parties while sacred ritual dramatises kinship relationships and so, the organisation of ploughing companies. , KMBT_363
- Full Text:
- Date Issued: 1990
- Authors: Heron, Gavin Stewart
- Date: 1990
- Subjects: Xhosa (African people) , Agriculture -- South Africa -- Transkei , Agriculture, Cooperative -- South Africa -- Transkei , Cooperative societies -- South Africa -- Transkei
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2109 , http://hdl.handle.net/10962/d1007448 , Xhosa (African people) , Agriculture -- South Africa -- Transkei , Agriculture, Cooperative -- South Africa -- Transkei , Cooperative societies -- South Africa -- Transkei
- Description: Incidences of cooperation in agricultural activity are widespread phenomena in low-income third world communities. Two forms of cooperative labour groupings are identified in Shixini, Transkei . These are the work party and the ploughing company. It is argued that different organisational principles operate in the different cooperative forms. Work parties are based on principles of neighbourhood whi Ie ploughing companies are organised around kinship relationships. Factors which determine the principle of organisation are social values; the wider South African economic system; ecology; reciprocity; the constitution and structure of the household; economic differentiation; and labour demand and supply. The dissertation is divided into five chapters. The first is an overview of the Shixini social, economic and political systems. This chapter discusses the influence of the wider South African politico-economic system on agricultural production; the Shixini!Transkei political context; kinship and its relation to social organisation; and the likely effects of an agricultural 'betterment' scheme on the area. The second chapter is an overview of agricultural production in Shixini. It is found that the most significant determinants of agricultural production is the structure and constitution of the household and the way in which stock is distributed in the community. The third and fourth chapters describe and analyse Xhosa work parties and ploughing companies . Argument is lead as to the reasons for the specific organisational principles operating in each case. The penultimate chapter is an analysis of sacred and secular ritual. It is argued that both ritual forms reveal cooperative principles of organisation. Secular ritual dramatises the organisation of work parties while sacred ritual dramatises kinship relationships and so, the organisation of ploughing companies. , KMBT_363
- Full Text:
- Date Issued: 1990
Immunolocalisation of, and ultrastructural changes in the LH gonadotropes of Miniopterus schreibersii and Rhinolophus capensis (Mammalia: Chiroptera) in relation to their reproductive cycles
- Authors: Bojarski, Christina
- Date: 1990
- Subjects: Bats -- Reproduction
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5589 , http://hdl.handle.net/10962/d1002039
- Description: LH gonadotropes are successfully identified in the anterior pituitary of Minioptems schreibersii and Rhinolophus capensis, using immunogold labelling at the light and electron microscopy level. The gonadotropes are oval to polygonal in shape and possess numerous small secretory granules, which contain LH throughout the year. Their distribution is similar in both species, although the abundance varies slightly between species and sexes. Seasonal changes are detected in gonadotrope ultrastructure, pituitary LH levels, and plasma hormone levels, and activity pattern of LH gonadotropes generally coincide with reproductive activity in both bat species. In female M. schreibersii gonadotrope activity, pituitary LH, and plasma LH levels coincide with development, implantation and gestation. During the delayed implantation gonadotropes are inactive and and high follicular period of plasma LH levels are low, coinciding with corpus luteum inactivity and low plasma progesterone levels. Implantation coincides with increased activity of the gonadotrope activity, increased plasma LH levels, reactivation of the corpus luteum and elevated plasma progesterone levels. Activation of LH gonadotropes towards the end of hibernation may be initiated by the winter solstice, which marks the change to increasing daylength. In female R capensis gonadotrope activity and high pituitary and plasma LH levels occur towards the end of follicular development. During hibernation gonadotrope activity and plasma LH levels decrease. Ovulation coincides with increasing gonadotrope activity (which follows the winter solstice), although a preovulatory peak in plasma LH is not detected. In male M. schreibersii and R. capensis, gonadotrope activity and high plasma LH and testosterone levels coincide with spermatogenesis, except during a period of reproductive inactivity in spring in male M. schreibersii, where gonadotropes appear active and plasma LH and testosterone levels are high. The reason for this apparent activity is not known. Male sperm storage during hibernation in male R. capensis coincides with low gonadotrope activity and low plasma LH and testosterone levels. Factors initiating gonadotrope activity and hence spermatogenesis are probably decreasing daylength (summer solstice) in M. schreibersii and increasing ambient temperatures and food abundance (following the hibernation period) in R.capensis.
- Full Text:
- Date Issued: 1990
- Authors: Bojarski, Christina
- Date: 1990
- Subjects: Bats -- Reproduction
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5589 , http://hdl.handle.net/10962/d1002039
- Description: LH gonadotropes are successfully identified in the anterior pituitary of Minioptems schreibersii and Rhinolophus capensis, using immunogold labelling at the light and electron microscopy level. The gonadotropes are oval to polygonal in shape and possess numerous small secretory granules, which contain LH throughout the year. Their distribution is similar in both species, although the abundance varies slightly between species and sexes. Seasonal changes are detected in gonadotrope ultrastructure, pituitary LH levels, and plasma hormone levels, and activity pattern of LH gonadotropes generally coincide with reproductive activity in both bat species. In female M. schreibersii gonadotrope activity, pituitary LH, and plasma LH levels coincide with development, implantation and gestation. During the delayed implantation gonadotropes are inactive and and high follicular period of plasma LH levels are low, coinciding with corpus luteum inactivity and low plasma progesterone levels. Implantation coincides with increased activity of the gonadotrope activity, increased plasma LH levels, reactivation of the corpus luteum and elevated plasma progesterone levels. Activation of LH gonadotropes towards the end of hibernation may be initiated by the winter solstice, which marks the change to increasing daylength. In female R capensis gonadotrope activity and high pituitary and plasma LH levels occur towards the end of follicular development. During hibernation gonadotrope activity and plasma LH levels decrease. Ovulation coincides with increasing gonadotrope activity (which follows the winter solstice), although a preovulatory peak in plasma LH is not detected. In male M. schreibersii and R. capensis, gonadotrope activity and high plasma LH and testosterone levels coincide with spermatogenesis, except during a period of reproductive inactivity in spring in male M. schreibersii, where gonadotropes appear active and plasma LH and testosterone levels are high. The reason for this apparent activity is not known. Male sperm storage during hibernation in male R. capensis coincides with low gonadotrope activity and low plasma LH and testosterone levels. Factors initiating gonadotrope activity and hence spermatogenesis are probably decreasing daylength (summer solstice) in M. schreibersii and increasing ambient temperatures and food abundance (following the hibernation period) in R.capensis.
- Full Text:
- Date Issued: 1990
Initial findings of an investigation into the feasibility of a low level image processing workstation using transputers
- Authors: Cooke, Nicholas Duncan
- Date: 1990 , 2013-02-07
- Subjects: Image processing , Computer graphics , Fourier transformations -- Data processing , Transputers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4679 , http://hdl.handle.net/10962/d1006702 , Image processing , Computer graphics , Fourier transformations -- Data processing , Transputers
- Description: From Introduction: The research concentrates primarily on a feasibility study involving the setting up of an image processing workstation. As broad as this statement concerning the workstation may seem, there are several factors limiting the extent of the research. This project is not concerned with the design and implementation of a fully-fledged image processing workstation. Rather, it concerns an initial feasibility study of such a workstation, centered on the theme image processing aided by the parallel processing paradigm. In looking at the hardware available for the project, in the context of an image processing environment, a large amount of initial investigation was required prior to that concerned with the transputer and parallel processing. Work was done on the capturing and displaying of images. This formed a vital part of the project. Furthermore, considering that a new architecture was being used as the work horse within a conventional host architecture, the INTEL 80286, several aspects of the host architecture had also to be investigated. These included the actual processing capabilities of the host, the capturing and storing of the images on the host, and most importantly, the interface between the host and the transputer [C0089]. Benchmarking was important in order for good conclusions to be drawn about the viability of the two types of hardware used, both individually and together. On the subject of the transputer as the workhorse, there were several areas whlch required investigation. Initial work had to cover the choice of network topology on whlch the benchmarking of some of the image processing applications were performed. Research into this was based on the previous work of several authors, whlch introduced features relevant to this investigation. The network used for this investigation was chosen to be generally applicable to a broad spectrum of applications in image processing. It was not chosen for its applicability for a single dedicated application, as has been the case for much of the past research performed in image processing [SAN88] [SCH89]. The concept of image processing techniques being implemented on the transputer required careful consideration in respect of what should be implemented. Image processing is not a new subject, and it encompasses a large spectrum of applications. The transputer, with image processing being hlghly suited to it, has attracted a good deal of research. It would not be rash to say that the easy research was covered first. The more trivial operations in image processing, requiring matrix type operations on the pixels attracted, the most coverage. Several researchers in the field of image processing on the transputer have broken the back of this set of problems. Conclusions regarding these operations on the transputer returned a fairly standard answer. An area of image processing which has not produced the same volume of return as that concerning the more trivial operations, is the subject of Fourier Analysis, that is, the Fourier Transform. Thus a major part of this project concerns an investigation into the Fourier Transform in image processing, in particular the Fast Fourier Transform. The network chosen for thls research has placed some constraint upon the degree of parallelism that can be achleved. It should be emphasized that this project is not concerned with the most efficient implementation of a specific image processing algorithm on a dedicated topology. Rather, it looks at the feasibility of a general system in the domain of image processing, concerned with a hlghly computationally intensive operation. This has had the effect of testing the processing power of the hardware used, and contributing a widely applicable parallel algorithm for use in Fourier Analysis. 3 These are discussed more fully in Chapter 2, which covers the work related to tbis project. The results of the investigation are presented along with a discussion of the methods throughout the thesis. The final chapter summarizes the findings of the research, assesses the value of the investigation, and points out areas for future investigation.
- Full Text:
- Date Issued: 1990
- Authors: Cooke, Nicholas Duncan
- Date: 1990 , 2013-02-07
- Subjects: Image processing , Computer graphics , Fourier transformations -- Data processing , Transputers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4679 , http://hdl.handle.net/10962/d1006702 , Image processing , Computer graphics , Fourier transformations -- Data processing , Transputers
- Description: From Introduction: The research concentrates primarily on a feasibility study involving the setting up of an image processing workstation. As broad as this statement concerning the workstation may seem, there are several factors limiting the extent of the research. This project is not concerned with the design and implementation of a fully-fledged image processing workstation. Rather, it concerns an initial feasibility study of such a workstation, centered on the theme image processing aided by the parallel processing paradigm. In looking at the hardware available for the project, in the context of an image processing environment, a large amount of initial investigation was required prior to that concerned with the transputer and parallel processing. Work was done on the capturing and displaying of images. This formed a vital part of the project. Furthermore, considering that a new architecture was being used as the work horse within a conventional host architecture, the INTEL 80286, several aspects of the host architecture had also to be investigated. These included the actual processing capabilities of the host, the capturing and storing of the images on the host, and most importantly, the interface between the host and the transputer [C0089]. Benchmarking was important in order for good conclusions to be drawn about the viability of the two types of hardware used, both individually and together. On the subject of the transputer as the workhorse, there were several areas whlch required investigation. Initial work had to cover the choice of network topology on whlch the benchmarking of some of the image processing applications were performed. Research into this was based on the previous work of several authors, whlch introduced features relevant to this investigation. The network used for this investigation was chosen to be generally applicable to a broad spectrum of applications in image processing. It was not chosen for its applicability for a single dedicated application, as has been the case for much of the past research performed in image processing [SAN88] [SCH89]. The concept of image processing techniques being implemented on the transputer required careful consideration in respect of what should be implemented. Image processing is not a new subject, and it encompasses a large spectrum of applications. The transputer, with image processing being hlghly suited to it, has attracted a good deal of research. It would not be rash to say that the easy research was covered first. The more trivial operations in image processing, requiring matrix type operations on the pixels attracted, the most coverage. Several researchers in the field of image processing on the transputer have broken the back of this set of problems. Conclusions regarding these operations on the transputer returned a fairly standard answer. An area of image processing which has not produced the same volume of return as that concerning the more trivial operations, is the subject of Fourier Analysis, that is, the Fourier Transform. Thus a major part of this project concerns an investigation into the Fourier Transform in image processing, in particular the Fast Fourier Transform. The network chosen for thls research has placed some constraint upon the degree of parallelism that can be achleved. It should be emphasized that this project is not concerned with the most efficient implementation of a specific image processing algorithm on a dedicated topology. Rather, it looks at the feasibility of a general system in the domain of image processing, concerned with a hlghly computationally intensive operation. This has had the effect of testing the processing power of the hardware used, and contributing a widely applicable parallel algorithm for use in Fourier Analysis. 3 These are discussed more fully in Chapter 2, which covers the work related to tbis project. The results of the investigation are presented along with a discussion of the methods throughout the thesis. The final chapter summarizes the findings of the research, assesses the value of the investigation, and points out areas for future investigation.
- Full Text:
- Date Issued: 1990
Interactions between fig wasps and their host figs
- Authors: Nefdt, Rory John Charlton
- Date: 1990
- Subjects: Wasps , Mutualism (Biology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5718 , http://hdl.handle.net/10962/d1005404 , Wasps , Mutualism (Biology)
- Description: Fig trees (Ficus spp.) and fig wasps (Hymenoptera: Agaonidae) are partners in an intimate mutualism. The trees provide ovules in which wasp larvae develop while the wasps pollinate the flowers and are therefore indispensible for fig seed production. Agaonid fig wasps oviposit down the styles of fig flowers and it has generally been accepted that they were unable to reach the ovules of "long" styled flowers , which would produce seeds, thus maintaining an evolutionary stable mutualism. African fig species were found to have unimodal style length frequencies, with no separation into long and short styled flowers. In several species the ovipositors of their associated agaonids were long enough to reach the majority of ovules. The number of foundress agaonids entering a fig influenced fig seed set and therefore was an important factor regulating the proportion of flowers producing seeds or pollinators. In the two Ficus species that were studied, entry of more than three agaonid foundresses into one fig resulted in competition for limited oviposition sites and less female - biased offspring sex ratios. It is hypothesised that sequential laying of male eggs followed by female eggs, under variable oviposition site limitation, results in sex ratio adjustment, as predicted by local mate competition theory. Evidence in support of this hypothesis is presented. A number of non - pollinating torymid and pteromalid fig wasps also oviposit into each fig species. The sycophagines and sycoecines oviposit down the styles from inside the fig inflorescences like their agaonid counterparts, while other species insert their ovipositors through the wall of the fig from the outside. Like the agaonids, sycophagines were characterised by being pro - ovigenic, with numerous fully developed eggs at emergence. Sycoecines were able to re - emerge from figs they had oviposited in and lay their eggs in more than one fig. They had short ovipositors, allowing access to a smaller proportion of flowers than agaonids or sycophagines. Externally ovipositing fig wasps were syn-ovigenic, able to develop eggs as adults and invested more energy and time during each oviposition event. Differences in the ovipositor lengths of these species did not segregate their oviposition sites spatially, and therefore does not reduce competition between species. Attack by parasitoids and inquiline fig wasps from the exterior did not constitute a selection pressure against agaonids ovipositing in ovules closer to the periphery of the fig's surface, as predicted by Michaloud's enemy-free-space hypothes is. It cannot therefore explain the preference shown by ovipositing agaonids for shorter styled flowers.
- Full Text:
- Date Issued: 1990
- Authors: Nefdt, Rory John Charlton
- Date: 1990
- Subjects: Wasps , Mutualism (Biology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5718 , http://hdl.handle.net/10962/d1005404 , Wasps , Mutualism (Biology)
- Description: Fig trees (Ficus spp.) and fig wasps (Hymenoptera: Agaonidae) are partners in an intimate mutualism. The trees provide ovules in which wasp larvae develop while the wasps pollinate the flowers and are therefore indispensible for fig seed production. Agaonid fig wasps oviposit down the styles of fig flowers and it has generally been accepted that they were unable to reach the ovules of "long" styled flowers , which would produce seeds, thus maintaining an evolutionary stable mutualism. African fig species were found to have unimodal style length frequencies, with no separation into long and short styled flowers. In several species the ovipositors of their associated agaonids were long enough to reach the majority of ovules. The number of foundress agaonids entering a fig influenced fig seed set and therefore was an important factor regulating the proportion of flowers producing seeds or pollinators. In the two Ficus species that were studied, entry of more than three agaonid foundresses into one fig resulted in competition for limited oviposition sites and less female - biased offspring sex ratios. It is hypothesised that sequential laying of male eggs followed by female eggs, under variable oviposition site limitation, results in sex ratio adjustment, as predicted by local mate competition theory. Evidence in support of this hypothesis is presented. A number of non - pollinating torymid and pteromalid fig wasps also oviposit into each fig species. The sycophagines and sycoecines oviposit down the styles from inside the fig inflorescences like their agaonid counterparts, while other species insert their ovipositors through the wall of the fig from the outside. Like the agaonids, sycophagines were characterised by being pro - ovigenic, with numerous fully developed eggs at emergence. Sycoecines were able to re - emerge from figs they had oviposited in and lay their eggs in more than one fig. They had short ovipositors, allowing access to a smaller proportion of flowers than agaonids or sycophagines. Externally ovipositing fig wasps were syn-ovigenic, able to develop eggs as adults and invested more energy and time during each oviposition event. Differences in the ovipositor lengths of these species did not segregate their oviposition sites spatially, and therefore does not reduce competition between species. Attack by parasitoids and inquiline fig wasps from the exterior did not constitute a selection pressure against agaonids ovipositing in ovules closer to the periphery of the fig's surface, as predicted by Michaloud's enemy-free-space hypothes is. It cannot therefore explain the preference shown by ovipositing agaonids for shorter styled flowers.
- Full Text:
- Date Issued: 1990
Interrupt-generating active data objects
- Authors: Clayton, Peter Graham
- Date: 1990
- Subjects: Parallel programming (Computer science) Electronic data processing -- Distributed processing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4677 , http://hdl.handle.net/10962/d1006700
- Description: An investigation is presented into an interrupt-generating object model which is designed to reduce the effort of programming distributed memory multicomputer networks. The object model is aimed at the natural modelling of problem domains in which a number of concurrent entities interrupt one another as they lay claim to shared resources. The proposed computational model provides for the safe encapsulation of shared data, and incorporates inherent arbitration for simultaneous access to the data. It supplies a predicate triggering mechanism for use in conditional synchronization and as an alternative mechanism to polling. Linguistic support for the proposal requires a novel form of control structure which is able to interface sensibly with interrupt-generating active data objects. The thesis presents the proposal as an elemental language structure, with axiomatic guarantees which enforce safety properties and aid in program proving. The established theory of CSP is used to reason about the object model and its interface. An overview is presented of a programming language called HUL, whose semantics reflect the proposed computational model. Using the syntax of HUL, the application of the interrupt-generating active data object is illustrated. A range of standard concurrent problems is presented to demonstrate the properties of the interrupt-generating computational model. Furthermore, the thesis discusses implementation considerations which enable the model to be mapped precisely onto multicomputer networks, and which sustain the abstract programming level provided by the interrupt-generating active data object in the wider programming structures of HUL.
- Full Text:
- Date Issued: 1990
- Authors: Clayton, Peter Graham
- Date: 1990
- Subjects: Parallel programming (Computer science) Electronic data processing -- Distributed processing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4677 , http://hdl.handle.net/10962/d1006700
- Description: An investigation is presented into an interrupt-generating object model which is designed to reduce the effort of programming distributed memory multicomputer networks. The object model is aimed at the natural modelling of problem domains in which a number of concurrent entities interrupt one another as they lay claim to shared resources. The proposed computational model provides for the safe encapsulation of shared data, and incorporates inherent arbitration for simultaneous access to the data. It supplies a predicate triggering mechanism for use in conditional synchronization and as an alternative mechanism to polling. Linguistic support for the proposal requires a novel form of control structure which is able to interface sensibly with interrupt-generating active data objects. The thesis presents the proposal as an elemental language structure, with axiomatic guarantees which enforce safety properties and aid in program proving. The established theory of CSP is used to reason about the object model and its interface. An overview is presented of a programming language called HUL, whose semantics reflect the proposed computational model. Using the syntax of HUL, the application of the interrupt-generating active data object is illustrated. A range of standard concurrent problems is presented to demonstrate the properties of the interrupt-generating computational model. Furthermore, the thesis discusses implementation considerations which enable the model to be mapped precisely onto multicomputer networks, and which sustain the abstract programming level provided by the interrupt-generating active data object in the wider programming structures of HUL.
- Full Text:
- Date Issued: 1990
Isolation of and interaction of nutrients with the linoleoyl-coa desaturase complex
- Authors: Perkins, Denise Mary
- Date: 1990
- Subjects: Cell proliferation , Cancer cells -- Growth -- Regulation , Enzymes -- Purification
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4558 , http://hdl.handle.net/10962/d1018264
- Description: The termina1 enzyme in the linoleoyl-CoA desaturase enzyme complex, delta-6-desaturase was implied in the control of cell proliferation in cancer cells. One of the aims of this study was to isolate the terminal enzyme. It was decided that in order to isolate this enzyme it was first necessary to isolate the entire complex and then to enzymatically solubilise the first two components of the complex i e cytochrome b5 reductase and cytochrome b5 from the complex resulting in a pure delta-6-desaturase . The first two components were isolated and purified using simplified and easily reproducible methodologies which could be utilised in the final purification of delta-6- desaturase. The entire enzyme complex, linoleoyl-CoA desaturase was also isolated in a pure form and this pure complex was used to attempt to isolate delta-6-desaturase. The terminal enzyme was isolated with some cytochrome b5 still bound to it. The methods used had proven to be successful and with some modifications should yield a pure enzyme. Zinc and GLA were known to play a role in the inhibition of cancer cell proliferation and zinc was hypothesised to inhibit cell growth by stimulating the activity of the linoleoyl-CoA desaturase enzyme complex which is involved in the regulation of cell proliferation. GLA is the product of the reaction that this enzyme complex catalyses and GLA has been shown to inhibit cancer ce ll growth. The effect of GLA on cell growth and linoleoyl-CoA desaturase activity was thus investigated. Results showed that both zinc and GLA inhibited cell growth and that the combined addition of zinc and GLA generally resulted in the inhibition of cell growth and the activation of linoleoyl-CoA desaturase activity in the BL-6 cells while having a less pronounced effect on the LLCMK cells. The results of this study support the hypothesis that zinc may be a cofactor of linoleoyl-CoA desaturase.
- Full Text:
- Date Issued: 1990
- Authors: Perkins, Denise Mary
- Date: 1990
- Subjects: Cell proliferation , Cancer cells -- Growth -- Regulation , Enzymes -- Purification
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4558 , http://hdl.handle.net/10962/d1018264
- Description: The termina1 enzyme in the linoleoyl-CoA desaturase enzyme complex, delta-6-desaturase was implied in the control of cell proliferation in cancer cells. One of the aims of this study was to isolate the terminal enzyme. It was decided that in order to isolate this enzyme it was first necessary to isolate the entire complex and then to enzymatically solubilise the first two components of the complex i e cytochrome b5 reductase and cytochrome b5 from the complex resulting in a pure delta-6-desaturase . The first two components were isolated and purified using simplified and easily reproducible methodologies which could be utilised in the final purification of delta-6- desaturase. The entire enzyme complex, linoleoyl-CoA desaturase was also isolated in a pure form and this pure complex was used to attempt to isolate delta-6-desaturase. The terminal enzyme was isolated with some cytochrome b5 still bound to it. The methods used had proven to be successful and with some modifications should yield a pure enzyme. Zinc and GLA were known to play a role in the inhibition of cancer cell proliferation and zinc was hypothesised to inhibit cell growth by stimulating the activity of the linoleoyl-CoA desaturase enzyme complex which is involved in the regulation of cell proliferation. GLA is the product of the reaction that this enzyme complex catalyses and GLA has been shown to inhibit cancer ce ll growth. The effect of GLA on cell growth and linoleoyl-CoA desaturase activity was thus investigated. Results showed that both zinc and GLA inhibited cell growth and that the combined addition of zinc and GLA generally resulted in the inhibition of cell growth and the activation of linoleoyl-CoA desaturase activity in the BL-6 cells while having a less pronounced effect on the LLCMK cells. The results of this study support the hypothesis that zinc may be a cofactor of linoleoyl-CoA desaturase.
- Full Text:
- Date Issued: 1990
Persuasuve conflict: an hermeneutical model for interpreting Galatians in the context of the South African church
- Authors: Holgate, David A
- Date: 1990
- Subjects: Bible. Galatians -- Criticism, Textual , Liberation theology -- South Africa
- Language: English
- Type: Thesis , Masters , MTh
- Identifier: vital:1213 , http://hdl.handle.net/10962/d1001542
- Description: This study looks at how to interpret Paul's letter to the Galatians in the contemporary South African church. It aims to provide a Bible study method for doing this which accounts both for the context in which interpretation takes place and for the requirements of exegesis. To this end, use is made of a combination of contextual Bible study methods and a recent multidimensional exegetical model, all of which are currently employed in South Africa. Initially, the study surveys a range of recent critical approaches to the Pauline epistles, particularly as these are employed by South African scholars working on Galatians. The fact that different exegetical approaches focus on different dimensions of the text, reveals the usefulness of a multidimensional exegetical model. The multidimensional exegetical model of Rousseau, which functions within a communication paradigm, is then introduced as an exegetical guide. To meet the second requirement of this study, the question of contextual exegesis is examined. Particular use is made of the hermeneutical approach of liberation theology, with its three mediations of social analysis, theological reflection and practical implementation. The central part of this study explores the implications of contextual interpretation and multidimensional exegesis of Galatians. The pre-canonical, canonical and contemporary contexts which affect the understanding of Galatians are discussed, and the multidimensional exegetical model is used to introduce the Galatian letter as a whole. The last part deals with the practical questions of group Bible study. The exegetical and hermeneutical theory developed earlier is simplified to provide a contextual Bible study method and this method is applied to three pericopes from Galatians. The task of bridging the gap between the university and the church is not an easy one, nor one which is solved by a single Bible study method. The exegetical and hermeneutical questions raised here point to the need for ongoing interaction between South African community of biblical scholars and those involved in the everyday life of the South African church
- Full Text:
- Date Issued: 1990
- Authors: Holgate, David A
- Date: 1990
- Subjects: Bible. Galatians -- Criticism, Textual , Liberation theology -- South Africa
- Language: English
- Type: Thesis , Masters , MTh
- Identifier: vital:1213 , http://hdl.handle.net/10962/d1001542
- Description: This study looks at how to interpret Paul's letter to the Galatians in the contemporary South African church. It aims to provide a Bible study method for doing this which accounts both for the context in which interpretation takes place and for the requirements of exegesis. To this end, use is made of a combination of contextual Bible study methods and a recent multidimensional exegetical model, all of which are currently employed in South Africa. Initially, the study surveys a range of recent critical approaches to the Pauline epistles, particularly as these are employed by South African scholars working on Galatians. The fact that different exegetical approaches focus on different dimensions of the text, reveals the usefulness of a multidimensional exegetical model. The multidimensional exegetical model of Rousseau, which functions within a communication paradigm, is then introduced as an exegetical guide. To meet the second requirement of this study, the question of contextual exegesis is examined. Particular use is made of the hermeneutical approach of liberation theology, with its three mediations of social analysis, theological reflection and practical implementation. The central part of this study explores the implications of contextual interpretation and multidimensional exegesis of Galatians. The pre-canonical, canonical and contemporary contexts which affect the understanding of Galatians are discussed, and the multidimensional exegetical model is used to introduce the Galatian letter as a whole. The last part deals with the practical questions of group Bible study. The exegetical and hermeneutical theory developed earlier is simplified to provide a contextual Bible study method and this method is applied to three pericopes from Galatians. The task of bridging the gap between the university and the church is not an easy one, nor one which is solved by a single Bible study method. The exegetical and hermeneutical questions raised here point to the need for ongoing interaction between South African community of biblical scholars and those involved in the everyday life of the South African church
- Full Text:
- Date Issued: 1990
Radio studies of ionized hydrogen in the southern Milky Way
- Authors: Gaylard, Michael John
- Date: 1990
- Subjects: Interstellar hydrogen Milky Way Astrophysics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5440 , http://hdl.handle.net/10962/d1001993
- Description: This thesis describes the results of a survey of the HI42ɑ recombination line emission at 2.3 GHz from HII regions in the Southern Milky Way, carried out with the 26 m diameter Hartebeesthoek radio telescope. The Galactic Longitude range covered was 290° to 40°. Single recombination lines were detected from 375 positions. Multiple lines were observed towards 90 positions in the inner Galaxy. No line emission could be detected in 28 positions. Continuum antenna temperatures were estimated from drift scans or radio maps observed for the purpose. LTE electron temperatures and turbulent velocities of the HII regions were calculated where possible. The properties of the sample were compared to those observed in HI09ɑ surveys. The lines observed from over 50 positions were first detections, of which half were associated with optically-identified HII regions. In about 150 cases the lines were only the second to be detected from those HII regions. The processes of the radio emission, detection, and analysis were simulated numerically. The detectability of the emission and the magnitude of non-LTE effects and pressure-broadening in multi-component HII regions was predicted and compared to observations. The radio luminosity function of the HII regions was determined over a range of three orders of magnitude in intrinsic brightness for the first time, using techniques which corrected for different types of incompleteness in the samples. The luminosity function was compared to those in five selected spiral galaxies, and shown to lie between those of M33 and M81. An alternate form of the luminosity function was developed for use with a numerical model of the spiral arm structure of the Milky Way. The physical parameters defining the major spiral arms were established by comparing synthesized diagrams of radial velocity versus Galactic Longitude with those actually observed. The faint, extended HII regions S9 and RCW129 in Scorpius, the Barnard Loop in Orion, and S296 in Canis Major were analyzed, using all available data. All the recombination lines from these HII regions were first detections
- Full Text:
- Date Issued: 1990
- Authors: Gaylard, Michael John
- Date: 1990
- Subjects: Interstellar hydrogen Milky Way Astrophysics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5440 , http://hdl.handle.net/10962/d1001993
- Description: This thesis describes the results of a survey of the HI42ɑ recombination line emission at 2.3 GHz from HII regions in the Southern Milky Way, carried out with the 26 m diameter Hartebeesthoek radio telescope. The Galactic Longitude range covered was 290° to 40°. Single recombination lines were detected from 375 positions. Multiple lines were observed towards 90 positions in the inner Galaxy. No line emission could be detected in 28 positions. Continuum antenna temperatures were estimated from drift scans or radio maps observed for the purpose. LTE electron temperatures and turbulent velocities of the HII regions were calculated where possible. The properties of the sample were compared to those observed in HI09ɑ surveys. The lines observed from over 50 positions were first detections, of which half were associated with optically-identified HII regions. In about 150 cases the lines were only the second to be detected from those HII regions. The processes of the radio emission, detection, and analysis were simulated numerically. The detectability of the emission and the magnitude of non-LTE effects and pressure-broadening in multi-component HII regions was predicted and compared to observations. The radio luminosity function of the HII regions was determined over a range of three orders of magnitude in intrinsic brightness for the first time, using techniques which corrected for different types of incompleteness in the samples. The luminosity function was compared to those in five selected spiral galaxies, and shown to lie between those of M33 and M81. An alternate form of the luminosity function was developed for use with a numerical model of the spiral arm structure of the Milky Way. The physical parameters defining the major spiral arms were established by comparing synthesized diagrams of radial velocity versus Galactic Longitude with those actually observed. The faint, extended HII regions S9 and RCW129 in Scorpius, the Barnard Loop in Orion, and S296 in Canis Major were analyzed, using all available data. All the recombination lines from these HII regions were first detections
- Full Text:
- Date Issued: 1990
Religious experience and schizophrenia in modern man : an experiential theoretical study
- Borchardt, Frederick Francois
- Authors: Borchardt, Frederick Francois
- Date: 1990
- Subjects: Schizophrenia -- Religious aspects , Experience (Religion) -- Psychological aspects
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2897 , http://hdl.handle.net/10962/d1002061
- Description: In this study the psychological structures of two categories of religious and schizophrenic experience were examined from a phenomenological- existential perspective. Existing theories describe schizophrenia as an unfree, rigid experience with limited possibilities for selfhood. Some theorists believe, however, that some forms of schizophrenia can be seen as potential growth experiences which could facilitate existential renewal. These forms of schizophrenia are mystical, mythical or spiritual in nature. Religious experiences are, according to the literature, essentially renewal experiences facilitating existential growth and transformation through a particular system of thought and devotional relationship shared by a group of people. The Duquesne phenomenological- psychological method was used to analyse seven case studies, four of which involved schizophrenic experiences and three which involved religious conversion experiences. The general psychological structure which emerged through this analysis showed both schizophrenia and religious experience to have specific implications for the personal, social, material and mystical dimensions of being. The description of a specific psychological structure of experience which could optimally facilitate existential growth and transformation was attained by examining psychological structures where the subject's experience culminated in existential growth and transformation (such as religious experience and certain schizophrenIc experiences). As both these categories of experience displayed a strong mystical component, a psychological structure of experience which facilitates a transformative mystical experience was described. It can be concluded that an experience involving a mystical dimension could be transformative if the general psychological structure of the person displays (a) an openness towards reality as it presents itself (b) an experience of oneself as having a measure of existential freedom (c) a certain sense of security in one's own selfhood and (d) a social world which could understand, support and reflect inner experiences.
- Full Text:
- Date Issued: 1990
- Authors: Borchardt, Frederick Francois
- Date: 1990
- Subjects: Schizophrenia -- Religious aspects , Experience (Religion) -- Psychological aspects
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2897 , http://hdl.handle.net/10962/d1002061
- Description: In this study the psychological structures of two categories of religious and schizophrenic experience were examined from a phenomenological- existential perspective. Existing theories describe schizophrenia as an unfree, rigid experience with limited possibilities for selfhood. Some theorists believe, however, that some forms of schizophrenia can be seen as potential growth experiences which could facilitate existential renewal. These forms of schizophrenia are mystical, mythical or spiritual in nature. Religious experiences are, according to the literature, essentially renewal experiences facilitating existential growth and transformation through a particular system of thought and devotional relationship shared by a group of people. The Duquesne phenomenological- psychological method was used to analyse seven case studies, four of which involved schizophrenic experiences and three which involved religious conversion experiences. The general psychological structure which emerged through this analysis showed both schizophrenia and religious experience to have specific implications for the personal, social, material and mystical dimensions of being. The description of a specific psychological structure of experience which could optimally facilitate existential growth and transformation was attained by examining psychological structures where the subject's experience culminated in existential growth and transformation (such as religious experience and certain schizophrenIc experiences). As both these categories of experience displayed a strong mystical component, a psychological structure of experience which facilitates a transformative mystical experience was described. It can be concluded that an experience involving a mystical dimension could be transformative if the general psychological structure of the person displays (a) an openness towards reality as it presents itself (b) an experience of oneself as having a measure of existential freedom (c) a certain sense of security in one's own selfhood and (d) a social world which could understand, support and reflect inner experiences.
- Full Text:
- Date Issued: 1990
Sand inundation on rocky shores : its effects on species richness and the structure of species assemblages
- Authors: Dower, Katherine Mary
- Date: 1990
- Subjects: Intertidal ecology , Tide pool ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5814 , http://hdl.handle.net/10962/d1007183 , Intertidal ecology , Tide pool ecology
- Description: Although sand deposits are present on many intertidal rocky shores, their effects on species richness, zonation and trophic structure have often been overlooked. This study is the first to recognise sand as an important abiotic factor on South African rocky shores. Rocky shores in the eastern Cape Province of South Africa are subject to extensive sand inundation and are composed of two hard substrata of differing topographies. Four sites on one substratum and six on the other were sampled quantitatively using quadrats. The biota were identified, counted and/ or weighed to provide a matrix of species biomass and numbers in separate zones. This matrix was then analysed using ordination and classification. A total of 321 species were identified which is more than local rocky or sandy shores. While the intermediate disturbance hypothesis would predict high species richness on these shores, it does not fully explain this richness nor the distribution of species assemblages. Habitat heterogeneity, including the dynamics of sand deposits, is strongly influenced by substratum topography and is the most important factor generating species richness. Abrasion by sand (sand scour) causes local reductions in richness but the presence of semi-permanent sand deposits allows habitation by psammophilic and sand-dependent species. As a result the biota of a sand inundated rocky shore includes both a full rocky shore and a large sandy beach component. Substratum topography controls patterns of sand deposition and retention and community analysis showed that samples were clustered primarily according to species richness and secondarily according to substratum type. Ordination of species identified an arc of species assemblages of decreasing levels of sand tolerance. These corresponded to sample groupings so that th assemblages found in various habitats were characterised by particular levels of sand tolerance. The presence of sand has a negative effect on the biomass of primary producers and filter feeders but a positive effect on the biomass of deposit feeders. Because sand is retained to different degrees in different zones, trophic structure varies between zones and to a lesser extent, between rock types. In general, however, the trophic structure of sand inundated rocky shores is similar to that of non-inundated shores.
- Full Text:
- Date Issued: 1990
- Authors: Dower, Katherine Mary
- Date: 1990
- Subjects: Intertidal ecology , Tide pool ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5814 , http://hdl.handle.net/10962/d1007183 , Intertidal ecology , Tide pool ecology
- Description: Although sand deposits are present on many intertidal rocky shores, their effects on species richness, zonation and trophic structure have often been overlooked. This study is the first to recognise sand as an important abiotic factor on South African rocky shores. Rocky shores in the eastern Cape Province of South Africa are subject to extensive sand inundation and are composed of two hard substrata of differing topographies. Four sites on one substratum and six on the other were sampled quantitatively using quadrats. The biota were identified, counted and/ or weighed to provide a matrix of species biomass and numbers in separate zones. This matrix was then analysed using ordination and classification. A total of 321 species were identified which is more than local rocky or sandy shores. While the intermediate disturbance hypothesis would predict high species richness on these shores, it does not fully explain this richness nor the distribution of species assemblages. Habitat heterogeneity, including the dynamics of sand deposits, is strongly influenced by substratum topography and is the most important factor generating species richness. Abrasion by sand (sand scour) causes local reductions in richness but the presence of semi-permanent sand deposits allows habitation by psammophilic and sand-dependent species. As a result the biota of a sand inundated rocky shore includes both a full rocky shore and a large sandy beach component. Substratum topography controls patterns of sand deposition and retention and community analysis showed that samples were clustered primarily according to species richness and secondarily according to substratum type. Ordination of species identified an arc of species assemblages of decreasing levels of sand tolerance. These corresponded to sample groupings so that th assemblages found in various habitats were characterised by particular levels of sand tolerance. The presence of sand has a negative effect on the biomass of primary producers and filter feeders but a positive effect on the biomass of deposit feeders. Because sand is retained to different degrees in different zones, trophic structure varies between zones and to a lesser extent, between rock types. In general, however, the trophic structure of sand inundated rocky shores is similar to that of non-inundated shores.
- Full Text:
- Date Issued: 1990
Students' conceptions of simple D.C. electricity circuits: a study of primary, inappropriate conceptions, learning difficulties of physics students, and implications for instruction
- Authors: Jiya, Zindlovu
- Date: 1990
- Subjects: Physical sciences -- Study and teaching (Secondary) -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5441 , http://hdl.handle.net/10962/d1001994
- Description: The work attempts to identify the general conceptual problems of the generations of Black students who pass through flrst year physics courses at the University of Fort Hare. In particular the alternative conceptions of students in the area of direct current electricity are investigated, using various techniques including written diagnostic tests. The main method used in the investigation of the student frameworks is the personal interview. A varied number of inappropriate conceptions are identifled in the students in significantly large proportions, and these are found to be dependent on many factors; for example the socio-cultural background like language and its metaphors, and media images. It is established that some of these are exacerbated by student perceptions about the nature of physics and of the scientific enterprise in general. Certain proposals are made about how to remedy the situation; relying mainly on the recently established innovative instructional strategies like conceptual change and cognitive conflict, and on making proposals about restructuring certain forms of presentation of the subject matter, paying attention to how language is used to address the speciflc problems of the students. The importance of providing practical experiences for the students is also emphasised
- Full Text:
- Date Issued: 1990
- Authors: Jiya, Zindlovu
- Date: 1990
- Subjects: Physical sciences -- Study and teaching (Secondary) -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5441 , http://hdl.handle.net/10962/d1001994
- Description: The work attempts to identify the general conceptual problems of the generations of Black students who pass through flrst year physics courses at the University of Fort Hare. In particular the alternative conceptions of students in the area of direct current electricity are investigated, using various techniques including written diagnostic tests. The main method used in the investigation of the student frameworks is the personal interview. A varied number of inappropriate conceptions are identifled in the students in significantly large proportions, and these are found to be dependent on many factors; for example the socio-cultural background like language and its metaphors, and media images. It is established that some of these are exacerbated by student perceptions about the nature of physics and of the scientific enterprise in general. Certain proposals are made about how to remedy the situation; relying mainly on the recently established innovative instructional strategies like conceptual change and cognitive conflict, and on making proposals about restructuring certain forms of presentation of the subject matter, paying attention to how language is used to address the speciflc problems of the students. The importance of providing practical experiences for the students is also emphasised
- Full Text:
- Date Issued: 1990
Synthetic and spectrometric investigation of 1,4-benzoxazepines
- Authors: Whittal, R D
- Date: 1990
- Subjects: Spectrum analysis , Benzodiazepines
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4381 , http://hdl.handle.net/10962/d1005046
- Description: Flavanone (2,3-dihydro-2-phenyl-4H-benzopyran-4-one) and a series of 4'- and 7-halogeno derivatives were prepared from the corresponding 2'-hydroxychalcones [1-(2-hydroxyphenyl)-3-phenyl-2-propen-l-ones], which, in turn, were synthesized by aldol condensation of substituted 2'-hydroxacetophenones with various benzaldehydes. A series of 2,3-dihydro-2-phenyl-l,4-benzoxazepin-5(4H)-ones were prepared by ring expansion of the corresponding flavanones, via the Schmidt reaction, using trimethylsilylazide and trifluoroacetic acid. A series of tetrazoles {2,3-dihydro-2-phenyl-tetrazolo[1,5-d]-1,4-benzoxazepines} were also isolated as by-products of the Schmidt reaction. Flavanone oxime was synthesized for use in Beckmann reactions, and its molecular structure was determined by x-ray crystallography. Attempts to prepare 1,4-benzoxazepinone or its 1,5-analogue via Beckmann rearrangement of flavanone oxime, with polyphosphoric acid or phosphorus pentachloride catalysts, however, were unsuccessful. Several methods for introducing Δ²-unsaturation into the benzoxazepinone system were also examined. High resolution ¹H n.m.r., computer modelling, and molecular mechanics techniques were used to determine the conformations of the heterocycles of the benzoxazepinones and tetrazoles and results are compared with earlier studies in this field. Certain trends in the fragmentation patterns were observed in the low resolution mass spectra of the benzoxazepinones and tetrazoles, and high resolution mass spectrometric data were used to explore the major fragmentation patterns of these compounds.
- Full Text:
- Date Issued: 1990
- Authors: Whittal, R D
- Date: 1990
- Subjects: Spectrum analysis , Benzodiazepines
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4381 , http://hdl.handle.net/10962/d1005046
- Description: Flavanone (2,3-dihydro-2-phenyl-4H-benzopyran-4-one) and a series of 4'- and 7-halogeno derivatives were prepared from the corresponding 2'-hydroxychalcones [1-(2-hydroxyphenyl)-3-phenyl-2-propen-l-ones], which, in turn, were synthesized by aldol condensation of substituted 2'-hydroxacetophenones with various benzaldehydes. A series of 2,3-dihydro-2-phenyl-l,4-benzoxazepin-5(4H)-ones were prepared by ring expansion of the corresponding flavanones, via the Schmidt reaction, using trimethylsilylazide and trifluoroacetic acid. A series of tetrazoles {2,3-dihydro-2-phenyl-tetrazolo[1,5-d]-1,4-benzoxazepines} were also isolated as by-products of the Schmidt reaction. Flavanone oxime was synthesized for use in Beckmann reactions, and its molecular structure was determined by x-ray crystallography. Attempts to prepare 1,4-benzoxazepinone or its 1,5-analogue via Beckmann rearrangement of flavanone oxime, with polyphosphoric acid or phosphorus pentachloride catalysts, however, were unsuccessful. Several methods for introducing Δ²-unsaturation into the benzoxazepinone system were also examined. High resolution ¹H n.m.r., computer modelling, and molecular mechanics techniques were used to determine the conformations of the heterocycles of the benzoxazepinones and tetrazoles and results are compared with earlier studies in this field. Certain trends in the fragmentation patterns were observed in the low resolution mass spectra of the benzoxazepinones and tetrazoles, and high resolution mass spectrometric data were used to explore the major fragmentation patterns of these compounds.
- Full Text:
- Date Issued: 1990