Finite element modelling of magma convection and attendant groundwater flow
- Authors: Harrison, Keith
- Date: 1998
- Subjects: Groundwater flow , Magmas
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5467 , http://hdl.handle.net/10962/d1005252 , Groundwater flow , Magmas
- Description: This thesis describes preliminary two- and three-dimensional modelling of mass and heat transport of hot, molten magma in crustal intrusions and of the associated thermally induced flow of groundwater contained in the surrounding country rock. The aim of such modelling is to create a tool with which to predict the location of mineral deposits formed by the transport and subsequent precipitation of minerals dissolved in the convecting groundwater. The momentum equations (Navier-Stokes equations), continuity equation and energy equation are used in conjunction with specially constructed density and viscosity relationships to govern the mass and heat transport processes of magma and groundwater. Finite element methods are used to solve the equations numerically for some simple model geometries. These methods are implemented by a commercial computer software code which is manipulated with a control program constructed by the author for the purpose. The models are of simple two- or three-dimensional geometries which all have an enclosed magma chamber surrounded completely by a shell of country rock through which groundwater is free to move. Modelling begins immediately after the intrusive event when the magma (in most cases rhyolitic) is at its greatest temperature. Heat is allowed to flow from the magma into the country rock causing thermal convection of the groundwater contained therein. The effect of the country rock as a porous medium on the flow of groundwater is modelled by including a distributed resistance term in the momentum equation. The computer code that controls the modelling is such that adaptions made to the models to represent real physical intrusive systems are trivial. Results of the research at this stage allow approximate prediction of the location of mineral deposits. Enhanced predictions can be made by effecting improvements to the models such as a more detailed representation of chemical processes, adaption of the computer code to allow multiple injections of magma and the modelling of frozen magma as a porous medium which admits the flow of groundwater.
- Full Text:
- Authors: Harrison, Keith
- Date: 1998
- Subjects: Groundwater flow , Magmas
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5467 , http://hdl.handle.net/10962/d1005252 , Groundwater flow , Magmas
- Description: This thesis describes preliminary two- and three-dimensional modelling of mass and heat transport of hot, molten magma in crustal intrusions and of the associated thermally induced flow of groundwater contained in the surrounding country rock. The aim of such modelling is to create a tool with which to predict the location of mineral deposits formed by the transport and subsequent precipitation of minerals dissolved in the convecting groundwater. The momentum equations (Navier-Stokes equations), continuity equation and energy equation are used in conjunction with specially constructed density and viscosity relationships to govern the mass and heat transport processes of magma and groundwater. Finite element methods are used to solve the equations numerically for some simple model geometries. These methods are implemented by a commercial computer software code which is manipulated with a control program constructed by the author for the purpose. The models are of simple two- or three-dimensional geometries which all have an enclosed magma chamber surrounded completely by a shell of country rock through which groundwater is free to move. Modelling begins immediately after the intrusive event when the magma (in most cases rhyolitic) is at its greatest temperature. Heat is allowed to flow from the magma into the country rock causing thermal convection of the groundwater contained therein. The effect of the country rock as a porous medium on the flow of groundwater is modelled by including a distributed resistance term in the momentum equation. The computer code that controls the modelling is such that adaptions made to the models to represent real physical intrusive systems are trivial. Results of the research at this stage allow approximate prediction of the location of mineral deposits. Enhanced predictions can be made by effecting improvements to the models such as a more detailed representation of chemical processes, adaption of the computer code to allow multiple injections of magma and the modelling of frozen magma as a porous medium which admits the flow of groundwater.
- Full Text:
From confrontation to co-operation: new security challenges facing post-apartheid Southern Africa
- Authors: Monnakgotla, Kgomotso
- Date: 1998
- Subjects: Economic security -- Africa, Southern , Cooperation -- Africa, Southern , Africa, Southern -- Economic policy , Africa, Southern -- Foreign relations
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2807 , http://hdl.handle.net/10962/d1003017 , Economic security -- Africa, Southern , Cooperation -- Africa, Southern , Africa, Southern -- Economic policy , Africa, Southern -- Foreign relations
- Description: Trite as it may sound, the end of the Cold War is a landmark event in the history of human-kind. As such, this thesis was motivated by some of the international and local events that have taken place since the end of the 1980s. At the international level, the end of the Cold War has encouraged the re-examination of the concept of security. In Southern Africa too, this process has been strengthened by the demise of apartheid in South Africa. Initially challenged by a few academics, the traditional conception of security which perceived the threat to 'national' security primarily in the form of external military aggression no longer enjoys the primacy it was accorded during the Cold War era. A 'new' security discourse has emerged, and even though it has not yet made inroads into many governments' policy papers, there is some realisation that people's security concerns go beyond external military aggression to the state. Proponents of this 'new' thinking make reference to people-centred or human security - the notion that people and not the state, must be the objects of security. Arising from that, they point to the existence of many phenomena which should also be accorded security status especially in developing countries where people are confronted by life-threatening challenges such as disease, poverty, famine, and other challenges which do not necessarily threaten life, but if not tackled with urgency could transform themselves into the more conventional military threats. Here reference is made to the proliferation of small arms, political instability, mass migr?tions, and so on. In a region besotted by many of the challenges mentioned above, a security conception informed by the 'new' approach seems more appropriate. The outcome of the traditional approach to security is well known to the region many millions of lives were lost and it is estimated that billions of dollars in revenue were also lost, all in the name of maintaining the security of the South African state. Seeing neighbouring states as threats to its security because they accommodated liberation movements who occasionally instigated military attacks against Pretoria, the former apartheid state through its policy of 'Total Strategy' terrorised the entire region, including the majority of citizens within South Africa. However, since the end of apartheid in 1994, the new democratically elected South African government has committed itself to help build a politically stable, more secure, economically prosperous and integrated region. Through its accession to the Southern African Development Community (SADC), a body which it once tried to undermine, South Africa has further demonstrated a commitment to tackle some of the region's problems in unison with its former adversaries. Throughout the Southern African region there is a realisation that there are more long-term benefits to be gained by working together to tackle the challenges that confront almost all the countries in the region than trying to solve problems independently. Therefore through SADC, primarily a development-oriented body, Southern African states will also seek to address the region's security concerns. Many of the region's governments seem to show an understanding that security and development are intertwined - that they are two sides of the same coin whereby one cannot be attained without the other. Much as this understanding is laudable, in practice it does not seem as if it will translate to the prominence of so-called development issues or marginal security issues. Accepting the 'new' thinking on security also implies an acceptance of a wider range of security agents. It does not mean that by widening the agenda of security to include nonmilitary threats, more tasks will follow for the 'men' in uniform. What it means is that, the military establishment should no longer be the sole agent of security. Instead, where there is no military threat, resources should be channeled to other establishments such as those of health and research in order to fight the spread of AIDS. Furthermore, departments of water, environmental affairs, and so on, should be part of the security policy-making process. In addition, civil society should also be included in the policy-making process. Notwithstanding its limitations, and without undermining inter-governmental projects, civil society can at best promote security by serving as a watch-dog over policies adopted by governments. South Africa during the era of apartheid is a classic example of how governments cannot always be entrusted with the security of ordinary citizens. However, an examination of the structure and terms of reference of the newly created SADC Organ for Politics, Defence and Security (from henceforth referred to as the Organ) reflects a preponderance of the traditional/realist approach to addressing security concerns. It was conceived by, and is primarily constituted by the traditional establishments of security, that is, the military and the police. Some of the Organ's objectives include; security and defence cooperation through conflict prevention, management and resolution and mediation of disputes and conflicts. Nowhere is it evident that others besides those from a military/police background were involved in the formation of this important body. There is also no indication as to how other dimensions of security will be attained through the Organ. All this casts doubt regarding SADC's actual commitment to a development-oriented, people-centred and people-driven security. Nonetheless, current debates on security give hope to the notion that in the future, people's overall security needs will be addressed.
- Full Text:
- Authors: Monnakgotla, Kgomotso
- Date: 1998
- Subjects: Economic security -- Africa, Southern , Cooperation -- Africa, Southern , Africa, Southern -- Economic policy , Africa, Southern -- Foreign relations
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2807 , http://hdl.handle.net/10962/d1003017 , Economic security -- Africa, Southern , Cooperation -- Africa, Southern , Africa, Southern -- Economic policy , Africa, Southern -- Foreign relations
- Description: Trite as it may sound, the end of the Cold War is a landmark event in the history of human-kind. As such, this thesis was motivated by some of the international and local events that have taken place since the end of the 1980s. At the international level, the end of the Cold War has encouraged the re-examination of the concept of security. In Southern Africa too, this process has been strengthened by the demise of apartheid in South Africa. Initially challenged by a few academics, the traditional conception of security which perceived the threat to 'national' security primarily in the form of external military aggression no longer enjoys the primacy it was accorded during the Cold War era. A 'new' security discourse has emerged, and even though it has not yet made inroads into many governments' policy papers, there is some realisation that people's security concerns go beyond external military aggression to the state. Proponents of this 'new' thinking make reference to people-centred or human security - the notion that people and not the state, must be the objects of security. Arising from that, they point to the existence of many phenomena which should also be accorded security status especially in developing countries where people are confronted by life-threatening challenges such as disease, poverty, famine, and other challenges which do not necessarily threaten life, but if not tackled with urgency could transform themselves into the more conventional military threats. Here reference is made to the proliferation of small arms, political instability, mass migr?tions, and so on. In a region besotted by many of the challenges mentioned above, a security conception informed by the 'new' approach seems more appropriate. The outcome of the traditional approach to security is well known to the region many millions of lives were lost and it is estimated that billions of dollars in revenue were also lost, all in the name of maintaining the security of the South African state. Seeing neighbouring states as threats to its security because they accommodated liberation movements who occasionally instigated military attacks against Pretoria, the former apartheid state through its policy of 'Total Strategy' terrorised the entire region, including the majority of citizens within South Africa. However, since the end of apartheid in 1994, the new democratically elected South African government has committed itself to help build a politically stable, more secure, economically prosperous and integrated region. Through its accession to the Southern African Development Community (SADC), a body which it once tried to undermine, South Africa has further demonstrated a commitment to tackle some of the region's problems in unison with its former adversaries. Throughout the Southern African region there is a realisation that there are more long-term benefits to be gained by working together to tackle the challenges that confront almost all the countries in the region than trying to solve problems independently. Therefore through SADC, primarily a development-oriented body, Southern African states will also seek to address the region's security concerns. Many of the region's governments seem to show an understanding that security and development are intertwined - that they are two sides of the same coin whereby one cannot be attained without the other. Much as this understanding is laudable, in practice it does not seem as if it will translate to the prominence of so-called development issues or marginal security issues. Accepting the 'new' thinking on security also implies an acceptance of a wider range of security agents. It does not mean that by widening the agenda of security to include nonmilitary threats, more tasks will follow for the 'men' in uniform. What it means is that, the military establishment should no longer be the sole agent of security. Instead, where there is no military threat, resources should be channeled to other establishments such as those of health and research in order to fight the spread of AIDS. Furthermore, departments of water, environmental affairs, and so on, should be part of the security policy-making process. In addition, civil society should also be included in the policy-making process. Notwithstanding its limitations, and without undermining inter-governmental projects, civil society can at best promote security by serving as a watch-dog over policies adopted by governments. South Africa during the era of apartheid is a classic example of how governments cannot always be entrusted with the security of ordinary citizens. However, an examination of the structure and terms of reference of the newly created SADC Organ for Politics, Defence and Security (from henceforth referred to as the Organ) reflects a preponderance of the traditional/realist approach to addressing security concerns. It was conceived by, and is primarily constituted by the traditional establishments of security, that is, the military and the police. Some of the Organ's objectives include; security and defence cooperation through conflict prevention, management and resolution and mediation of disputes and conflicts. Nowhere is it evident that others besides those from a military/police background were involved in the formation of this important body. There is also no indication as to how other dimensions of security will be attained through the Organ. All this casts doubt regarding SADC's actual commitment to a development-oriented, people-centred and people-driven security. Nonetheless, current debates on security give hope to the notion that in the future, people's overall security needs will be addressed.
- Full Text:
Genre analysis and the teaching of academic literacy: a case study of an academic discipline in the social sciences
- Authors: Vorwerk, Shane Paul
- Date: 1998
- Subjects: Lectures and lecturing , Lecture method in teaching , Language and culture , Discourse analysis , Language and culture -- South Africa , English language -- Discourse analysis , Intercultural communication -- South Africa , English language -- Study and teaching -- South Africa -- Foreign speakers
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2365 , http://hdl.handle.net/10962/d1002648 , Lectures and lecturing , Lecture method in teaching , Language and culture , Discourse analysis , Language and culture -- South Africa , English language -- Discourse analysis , Intercultural communication -- South Africa , English language -- Study and teaching -- South Africa -- Foreign speakers
- Description: Students in tertiary educational institutions in South Africa come from many different backgrounds and have varied educational experiences. Some students, especially those from non-English speaking backgrounds, may encounter linguistic difficulties with various academic tasks. In order for students to be successful at university, they must become academically literate. That is, they must master all the reading, writing, listening and comprehension tasks required by the disciplines in which they are studying. One such task is presented by the academic lecture which is an integral part of any course of study. Linguistically, the academic lecture can be seen as a particular genre with unique characteristics. This study investigated some linguistic characteristics of academic lectures. The discipline of Political Science, as a Social Science, was chosen because there is little research that has been done on language in the Social Sciences. The Political Science sub-disciplines of Political Philosophy, South African Politics, and International Relations were used in this research. First year lectures were recorded from each of these three sub-disciplines. The linguistic characteristics of lectures were analysed using techniques drawn from Systemic Functional linguistic theory. The analysis concentrated on the aspects mode and field as they were realised in the lectures. In addition, higher level generic structure was also analysed. The insights gained from the analysis were validated through interviews with the lecturers who gave the lectures. The aim of this research was to develop a linguistic characterisation of the lecture genre as it occurs in the three sub-disciplines of Political Science. The results of this research suggest that although there is a unified academic lecture genre, there is variation according to sub-discipline. The implications of this variation are discussed with reference to their relevance to teaching academic literacy.
- Full Text:
- Authors: Vorwerk, Shane Paul
- Date: 1998
- Subjects: Lectures and lecturing , Lecture method in teaching , Language and culture , Discourse analysis , Language and culture -- South Africa , English language -- Discourse analysis , Intercultural communication -- South Africa , English language -- Study and teaching -- South Africa -- Foreign speakers
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2365 , http://hdl.handle.net/10962/d1002648 , Lectures and lecturing , Lecture method in teaching , Language and culture , Discourse analysis , Language and culture -- South Africa , English language -- Discourse analysis , Intercultural communication -- South Africa , English language -- Study and teaching -- South Africa -- Foreign speakers
- Description: Students in tertiary educational institutions in South Africa come from many different backgrounds and have varied educational experiences. Some students, especially those from non-English speaking backgrounds, may encounter linguistic difficulties with various academic tasks. In order for students to be successful at university, they must become academically literate. That is, they must master all the reading, writing, listening and comprehension tasks required by the disciplines in which they are studying. One such task is presented by the academic lecture which is an integral part of any course of study. Linguistically, the academic lecture can be seen as a particular genre with unique characteristics. This study investigated some linguistic characteristics of academic lectures. The discipline of Political Science, as a Social Science, was chosen because there is little research that has been done on language in the Social Sciences. The Political Science sub-disciplines of Political Philosophy, South African Politics, and International Relations were used in this research. First year lectures were recorded from each of these three sub-disciplines. The linguistic characteristics of lectures were analysed using techniques drawn from Systemic Functional linguistic theory. The analysis concentrated on the aspects mode and field as they were realised in the lectures. In addition, higher level generic structure was also analysed. The insights gained from the analysis were validated through interviews with the lecturers who gave the lectures. The aim of this research was to develop a linguistic characterisation of the lecture genre as it occurs in the three sub-disciplines of Political Science. The results of this research suggest that although there is a unified academic lecture genre, there is variation according to sub-discipline. The implications of this variation are discussed with reference to their relevance to teaching academic literacy.
- Full Text:
Graphicacy as a form of communication in the primary school
- Authors: Wilmot, Pamela Dianne
- Date: 1998
- Subjects: School children -- South Africa Visual communication Perception in children Visual literacy Pictures
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1551 , http://hdl.handle.net/10962/d1003433
- Description: Children of today inhabit a multi-dimensional world, and in order to communicate effectively in it, they need the ability to utilise four forms of communication namely, oracy, literacy, numeracy and graphicacy. Communicating in graphic form requires an ability to both encode and decode spatial information using symbols, which requires the utilisation and application of spatial perceptual skills and concepts. The acquisition of graphic skills has been influenced by traditional developmental perspectives; increasingly the assumptions underpinning these have been challenged by more recent international research findings. The draft Curriculum Framework for General and Further Education and Training (1996: 18) identifies graphic literacy as one of the critical outcomes of the new South African curriculum. For graphic literacy to be an achievable outcome of the new curriculum, we need to investigate the skills and concepts underpinning this form of communication. The goal of this research is to investigate graphicacy as a form of communication in South African primary schools. However, given the scope of a research project of this nature, it was decided that rather than dealing with graphicacy per se, pictures as the most frequent and concrete type of graphic communication encountered by young learners would be focused on. In seeking to investigate pictures, the first stage of the study is concerned with diagnosing and illuminating children's graphic skill development through identifying: what skills they use; how they use and apply these when communicating through and interpreting symbols; and the difficulties they experience when, firstly, encoding spatial information through a series of practical and drawing tasks; and secondly, when reading and interpreting pictures. The second stage of the study investigates the extent to which children's early childhood experiences may or may not have impeded or enhanced the acquisition of skills necessary for understanding and communicating about space. The research findings, evaluated according to existing and emerging theoretical perspectives on graphicacy, will help to illuminate the current situation regarding the graphic literacy of South African primary school children. The study may contribute to wider international debates about graphicacy as a form of communication and the development of graphic literacy, from a South African perspective.
- Full Text:
- Authors: Wilmot, Pamela Dianne
- Date: 1998
- Subjects: School children -- South Africa Visual communication Perception in children Visual literacy Pictures
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1551 , http://hdl.handle.net/10962/d1003433
- Description: Children of today inhabit a multi-dimensional world, and in order to communicate effectively in it, they need the ability to utilise four forms of communication namely, oracy, literacy, numeracy and graphicacy. Communicating in graphic form requires an ability to both encode and decode spatial information using symbols, which requires the utilisation and application of spatial perceptual skills and concepts. The acquisition of graphic skills has been influenced by traditional developmental perspectives; increasingly the assumptions underpinning these have been challenged by more recent international research findings. The draft Curriculum Framework for General and Further Education and Training (1996: 18) identifies graphic literacy as one of the critical outcomes of the new South African curriculum. For graphic literacy to be an achievable outcome of the new curriculum, we need to investigate the skills and concepts underpinning this form of communication. The goal of this research is to investigate graphicacy as a form of communication in South African primary schools. However, given the scope of a research project of this nature, it was decided that rather than dealing with graphicacy per se, pictures as the most frequent and concrete type of graphic communication encountered by young learners would be focused on. In seeking to investigate pictures, the first stage of the study is concerned with diagnosing and illuminating children's graphic skill development through identifying: what skills they use; how they use and apply these when communicating through and interpreting symbols; and the difficulties they experience when, firstly, encoding spatial information through a series of practical and drawing tasks; and secondly, when reading and interpreting pictures. The second stage of the study investigates the extent to which children's early childhood experiences may or may not have impeded or enhanced the acquisition of skills necessary for understanding and communicating about space. The research findings, evaluated according to existing and emerging theoretical perspectives on graphicacy, will help to illuminate the current situation regarding the graphic literacy of South African primary school children. The study may contribute to wider international debates about graphicacy as a form of communication and the development of graphic literacy, from a South African perspective.
- Full Text:
Group problem solving among community activists in a South African setting: an everyday cognition approach
- Authors: Van Vlaenderen, Hilde
- Date: 1998
- Subjects: Group problem solving Group problem solving -- South Africa Cross-cultural studies -- Methodology Cognition Cross-cultural studies Cognition -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3080 , http://hdl.handle.net/10962/d1002589
- Description: The study focuses on the everyday problem solving processes of a group of community activists in a rural setting in the Eastern Cape Province of South Africa. It aims to uncover: first, the local knowledge of the participants of the study with reference to the concepts problem and problem solving; second, the participants' group problem solving procedure; and third, the dialectical interrelation between the participants' knowledge and practice with reference to everyday group problem solving. It is contended that the mainstream cognitive approach and the cross-cultural tradition are inappropriate for the study of everyday cognitive processes. A ‘situated cognition’ approach, based on the notions of activity and cultural mediation, is proposed as a theoretical framework for the study. The ontological and epistemological assumptions underpinning the empirical study were derived from a scientific realist and a hermeneutical paradigm. Data for the inquiry into the local knowledge of the participants was collected through individual interviews. The data was interpreted, using the grounded theory techniques of constant comparison, coding and compiling theoretical diagrams. Data for the inquiry into the participants' group problem solving practice consisted of video-taped group problem solving processes. This data was analysed, using a multi layered process of progressively deeper interpretation, employing a reading guide technique. Analysis of the research data revealed that the participants perceived a problem as an impediment to satisfactory participation in society. Problem solving was considered as an emotive, cognitive and inter-active process, involving particular role players. This process had a certain structure, involved attitudes and actions and relied on particular resources. Successful problem solving was perceived to result in restoration of social equilibrium. The group problem solving procedure used by the participants consisted of a process of developing a common understanding and group consensus. The strategies employed in the process, the roles played by the participants, the rules adhered to by the participants and the structure underlying the process were all congruent with these aims. There was a mutually reinforcing interrelation between knowledge and practice with reference to the participants’ problem solving.
- Full Text:
- Authors: Van Vlaenderen, Hilde
- Date: 1998
- Subjects: Group problem solving Group problem solving -- South Africa Cross-cultural studies -- Methodology Cognition Cross-cultural studies Cognition -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3080 , http://hdl.handle.net/10962/d1002589
- Description: The study focuses on the everyday problem solving processes of a group of community activists in a rural setting in the Eastern Cape Province of South Africa. It aims to uncover: first, the local knowledge of the participants of the study with reference to the concepts problem and problem solving; second, the participants' group problem solving procedure; and third, the dialectical interrelation between the participants' knowledge and practice with reference to everyday group problem solving. It is contended that the mainstream cognitive approach and the cross-cultural tradition are inappropriate for the study of everyday cognitive processes. A ‘situated cognition’ approach, based on the notions of activity and cultural mediation, is proposed as a theoretical framework for the study. The ontological and epistemological assumptions underpinning the empirical study were derived from a scientific realist and a hermeneutical paradigm. Data for the inquiry into the local knowledge of the participants was collected through individual interviews. The data was interpreted, using the grounded theory techniques of constant comparison, coding and compiling theoretical diagrams. Data for the inquiry into the participants' group problem solving practice consisted of video-taped group problem solving processes. This data was analysed, using a multi layered process of progressively deeper interpretation, employing a reading guide technique. Analysis of the research data revealed that the participants perceived a problem as an impediment to satisfactory participation in society. Problem solving was considered as an emotive, cognitive and inter-active process, involving particular role players. This process had a certain structure, involved attitudes and actions and relied on particular resources. Successful problem solving was perceived to result in restoration of social equilibrium. The group problem solving procedure used by the participants consisted of a process of developing a common understanding and group consensus. The strategies employed in the process, the roles played by the participants, the rules adhered to by the participants and the structure underlying the process were all congruent with these aims. There was a mutually reinforcing interrelation between knowledge and practice with reference to the participants’ problem solving.
- Full Text:
Growth, reproduction and feeding biology of Turbo sarmaticus (Mollusca : Vetigastropoda) along the coast of the Eastern Cape Province of South Africa
- Authors: Foster, Gregory George
- Date: 1998
- Subjects: Turbinidae -- Ecology -- Research -- South Africa Turbinidae -- Research -- South Africa Mollusks -- Research -- South Africa Abalones -- Ecology -- South Africa -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5705 , http://hdl.handle.net/10962/d1005391
- Description: Investigations were carried out on aspects of the biology of the vetigastropod Turbo sarmaticus. Studies included: 1) the distribution and standing stock of this animal at four sites along the coast of the Eastern Cape Province of South Africa; 2) the growth rate of animals on a wave-cut platform; 3) the reproductive cycle of an intertidal population; and 4) aspects of the feeding biology examining the ability of this mollusc to consume and digest six macroalgae, the influence of algal diet on growth rate and reproductive fitness and the polysaccharolytic activity of the digestive enzymes. On eastern Cape shores, T. sarmaticus had a size related distribution, with smaller animals being found towards the upper mid-shore and larger animals being found in a downshore direction. The mean shore densities of T. sarmaticus at three sites where exploitation of animals was minimal, were very similar (1.2 - 1.7 individuals/m²). The largest animals (up to 110 mm shell length) were found on an offshore island. This may have been a result of animals not being exploited, as well as a possible increase in primary productivity and food availability. The lowest density (0.2 individuals/m²) and animal size (<70 mm shell length) was recorded at a site (Kelly's beach - Port Alfred) where exploitation was more intense. It is probable that intense overexploitation was threatening the populations at this site. The growth rate of T. sarmaticus was determined by means of the von Bertalanffy growth model and expressed by the equation L[subscript]t = 81.07(l-e⁻°·⁵⁴⁴[superscript](t)). The initial growth rate of T. sarmaticus (up to ≈ 80 mm shell length) was similar on shores with different geomorphologies (i.e. boulder shores and wave-cut platforms). Growth rates of individuals were variable, which means that individuals within a population reached exploitable size (3 - 6 years old) and sexual maturity (1.5 - 2 years old) at different ages. Seasonality of reproduction of T. sarmaticus was determined using gonad index, egg diameters and spermatozoa content within the gonad. Turbo sarmaticus was dioecious and had a sex ratio in favour of males (1.2: 1). Animals attained sexual maturity at a size of about 52.5 mm shell length. There was little variation in the reproductive cycle over time with gametogenesis occurring from March/April until August/September, whilst maturity (Gonad Index = 15%) was maintained until the spawning event from December to March. After spawning the gonad regressed. Field and laboratory observations of the feeding biology of T. sarmaticus confirmed that this mollusc was a generalist grazer capable of consuming and digesting algae from the Rhodophyta, Chlorophyta and Phaeophyta. The consumption rates (juveniles: 1.45 - 9.50% body weight/day, adults: 1.06 - 6.08%) and digestibility (9 - 75% apparent dry matter) of six macroalgae was found to vary. For most algae, juvenile T. sarmaticus had higher consumption rates (1.6 - 2.8 times higher) and digestibility values (12 - 24% higher) than adults. It is suggested that consumption rates were dependent on the digestibility of the algae. In addition, it is suggested that the consumption rates of the different algae were not related to the nutritional content, but rather the energetic content of the algae. In both juvenile and adult animals, temperature had a positive influence on consumption rates, resulting in an increase at higher temperatures. However, in both juvenile and adult T. sarmaticus, algal digestibility was not affected by temperature. Finally, it was proposed that Viva rigida, Codium extricatum, Ecklonia radiata and Gelidium pristoides would provide the best nutritional value for growth and reproductive fitness in T. sarmaticus, whilst Jyengaria stellata and Corallina spp. would provide the poorest. Experiments on the effects of four algal diets on the biology of T. sarmaticus showed that the best growth rate (up to 13.8 mm shell length increase per annum), reproductive fitness (Gonad Index up to 33%) and energy levels (up to 4.76% glycogen in the foot) were achieved when T. sarmaticus was fed G. pristoides, U. rigid a or a mixed diet. Turbo sarmaticus fed Corallina spp. showed reduced growth (2.4 mm shell length increase), reproductive fitness (Gonad Index up to 4.4%) and energy levels (up to 3.42% glycogen in the foot). A study of the polysaccharolytic enzyme activity of T. sarmaticus indicated that this mollusc possesses enzymes that can, at least partially, digest most of the storage and structural polysaccharides found in the Chlorophyta, Rhodophyta and Phaeophyta. This further supported the findings that T. sarmaticus was a generalist grazer. Two levels of activity were detected: 1) high levels of enzyme activity (up to 328.2 Ilglmglmllhr)occurred on the storage polysaccharides that occur in the Rhodophyta and Chlorophyta, and 2) lower levels of activity were detected on the storage polysaccharides (up to 44.8 μg/mg/ml/hr) of the Phaeophyta and on all the structural polysaccharides tested (<45.5 μg/mg/ml/hr). It was suggested that T. sarmaticus did not rely heavily on structural carbohydrates as a source of carbon. Finally, the results of this study were discussed in relation to the future management of T. sarmaticus stocks, the possible role of this macro algal grazer in the intertidal zone and the effects of over-exploitation of this animal. The potential aquaculture of this mollusc was also addressed briefly.
- Full Text:
- Authors: Foster, Gregory George
- Date: 1998
- Subjects: Turbinidae -- Ecology -- Research -- South Africa Turbinidae -- Research -- South Africa Mollusks -- Research -- South Africa Abalones -- Ecology -- South Africa -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5705 , http://hdl.handle.net/10962/d1005391
- Description: Investigations were carried out on aspects of the biology of the vetigastropod Turbo sarmaticus. Studies included: 1) the distribution and standing stock of this animal at four sites along the coast of the Eastern Cape Province of South Africa; 2) the growth rate of animals on a wave-cut platform; 3) the reproductive cycle of an intertidal population; and 4) aspects of the feeding biology examining the ability of this mollusc to consume and digest six macroalgae, the influence of algal diet on growth rate and reproductive fitness and the polysaccharolytic activity of the digestive enzymes. On eastern Cape shores, T. sarmaticus had a size related distribution, with smaller animals being found towards the upper mid-shore and larger animals being found in a downshore direction. The mean shore densities of T. sarmaticus at three sites where exploitation of animals was minimal, were very similar (1.2 - 1.7 individuals/m²). The largest animals (up to 110 mm shell length) were found on an offshore island. This may have been a result of animals not being exploited, as well as a possible increase in primary productivity and food availability. The lowest density (0.2 individuals/m²) and animal size (<70 mm shell length) was recorded at a site (Kelly's beach - Port Alfred) where exploitation was more intense. It is probable that intense overexploitation was threatening the populations at this site. The growth rate of T. sarmaticus was determined by means of the von Bertalanffy growth model and expressed by the equation L[subscript]t = 81.07(l-e⁻°·⁵⁴⁴[superscript](t)). The initial growth rate of T. sarmaticus (up to ≈ 80 mm shell length) was similar on shores with different geomorphologies (i.e. boulder shores and wave-cut platforms). Growth rates of individuals were variable, which means that individuals within a population reached exploitable size (3 - 6 years old) and sexual maturity (1.5 - 2 years old) at different ages. Seasonality of reproduction of T. sarmaticus was determined using gonad index, egg diameters and spermatozoa content within the gonad. Turbo sarmaticus was dioecious and had a sex ratio in favour of males (1.2: 1). Animals attained sexual maturity at a size of about 52.5 mm shell length. There was little variation in the reproductive cycle over time with gametogenesis occurring from March/April until August/September, whilst maturity (Gonad Index = 15%) was maintained until the spawning event from December to March. After spawning the gonad regressed. Field and laboratory observations of the feeding biology of T. sarmaticus confirmed that this mollusc was a generalist grazer capable of consuming and digesting algae from the Rhodophyta, Chlorophyta and Phaeophyta. The consumption rates (juveniles: 1.45 - 9.50% body weight/day, adults: 1.06 - 6.08%) and digestibility (9 - 75% apparent dry matter) of six macroalgae was found to vary. For most algae, juvenile T. sarmaticus had higher consumption rates (1.6 - 2.8 times higher) and digestibility values (12 - 24% higher) than adults. It is suggested that consumption rates were dependent on the digestibility of the algae. In addition, it is suggested that the consumption rates of the different algae were not related to the nutritional content, but rather the energetic content of the algae. In both juvenile and adult animals, temperature had a positive influence on consumption rates, resulting in an increase at higher temperatures. However, in both juvenile and adult T. sarmaticus, algal digestibility was not affected by temperature. Finally, it was proposed that Viva rigida, Codium extricatum, Ecklonia radiata and Gelidium pristoides would provide the best nutritional value for growth and reproductive fitness in T. sarmaticus, whilst Jyengaria stellata and Corallina spp. would provide the poorest. Experiments on the effects of four algal diets on the biology of T. sarmaticus showed that the best growth rate (up to 13.8 mm shell length increase per annum), reproductive fitness (Gonad Index up to 33%) and energy levels (up to 4.76% glycogen in the foot) were achieved when T. sarmaticus was fed G. pristoides, U. rigid a or a mixed diet. Turbo sarmaticus fed Corallina spp. showed reduced growth (2.4 mm shell length increase), reproductive fitness (Gonad Index up to 4.4%) and energy levels (up to 3.42% glycogen in the foot). A study of the polysaccharolytic enzyme activity of T. sarmaticus indicated that this mollusc possesses enzymes that can, at least partially, digest most of the storage and structural polysaccharides found in the Chlorophyta, Rhodophyta and Phaeophyta. This further supported the findings that T. sarmaticus was a generalist grazer. Two levels of activity were detected: 1) high levels of enzyme activity (up to 328.2 Ilglmglmllhr)occurred on the storage polysaccharides that occur in the Rhodophyta and Chlorophyta, and 2) lower levels of activity were detected on the storage polysaccharides (up to 44.8 μg/mg/ml/hr) of the Phaeophyta and on all the structural polysaccharides tested (<45.5 μg/mg/ml/hr). It was suggested that T. sarmaticus did not rely heavily on structural carbohydrates as a source of carbon. Finally, the results of this study were discussed in relation to the future management of T. sarmaticus stocks, the possible role of this macro algal grazer in the intertidal zone and the effects of over-exploitation of this animal. The potential aquaculture of this mollusc was also addressed briefly.
- Full Text:
HIV and metaphor: an imaginative response to illness
- Authors: Cardo, Julia Claire
- Date: 1998
- Subjects: HIV infections , Metaphor -- Psychological aspects , Imagery (Psychology) -- Therapeutic use
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2945 , http://hdl.handle.net/10962/d1002454 , HIV infections , Metaphor -- Psychological aspects , Imagery (Psychology) -- Therapeutic use
- Description: The medical model has been criticised for its failure to attend to individuals' experience of illness and the meaning they attribute to illness. HIV / AIDS has challenged its adequacy and brought the question of meaning in illness into sharp focus. This study aimed to understand what it means to live with HIV by exploring the fantasies, images and metaphors that make up the depth of such an experience. Phenomenology was deemed the appropriate approach, as it assigns epistemological significance to metaphor and ontological primacy to the lifeworld. An interview guide was fashioned from existing phenomenological literature and in-depth interviews were conducted with eight HIV -infected individuals. Five protocols were selected to constitute the study. In addition, an audio tape recording of one individual's metaphorical dialogue with HIV was obtained and transcribed. The three protocols with the richest content of imagery and metaphor were subjected to phenomenological explication. The remaining two protocols were used to support and clarify emergent meaning. A phenomenological explication of the data revealed a number of salient metaphors and themes. Upon being diagnosed with HIV, individuals were confronted with a socially and institutionally prescribed understanding of the disease; HIV as synonymous with AIDS and immediate death, HIV as sexual deviance, and HIV as myth. These metaphors influenced their conceptualisation and handling of HIV. Individual embodied metaphors included: embodying a heart of stone to live with HIV and perceiving HIV as a punishment from God, a demon from the Devil, a death sentence and a torture. Affectively, the experience of HIV was constituted as fear of physical disfigurement and exposure, anxiety, vulnerability, anger, betrayal, injustice and isolation. In a process of resolution and transformation, individuals imbibed positive metaphors with which to continue living with HIV. In order to cope with HIV, individuals seemed to negotiate a metaphorical space in which to dwell with their virus. This entailed establishing some form of dialogue with HIV or a Higher Power. This study revealed that metaphorical thinking about HIV /AIDS has a powerful impact on individuals' embodiment of their world. Metaphor is also an effective means Clf conveying and eliciting meaning in the experience of illness. Based upon these findings, it was suggested that metaphor be a prime focus for future research endeavours.
- Full Text:
- Authors: Cardo, Julia Claire
- Date: 1998
- Subjects: HIV infections , Metaphor -- Psychological aspects , Imagery (Psychology) -- Therapeutic use
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2945 , http://hdl.handle.net/10962/d1002454 , HIV infections , Metaphor -- Psychological aspects , Imagery (Psychology) -- Therapeutic use
- Description: The medical model has been criticised for its failure to attend to individuals' experience of illness and the meaning they attribute to illness. HIV / AIDS has challenged its adequacy and brought the question of meaning in illness into sharp focus. This study aimed to understand what it means to live with HIV by exploring the fantasies, images and metaphors that make up the depth of such an experience. Phenomenology was deemed the appropriate approach, as it assigns epistemological significance to metaphor and ontological primacy to the lifeworld. An interview guide was fashioned from existing phenomenological literature and in-depth interviews were conducted with eight HIV -infected individuals. Five protocols were selected to constitute the study. In addition, an audio tape recording of one individual's metaphorical dialogue with HIV was obtained and transcribed. The three protocols with the richest content of imagery and metaphor were subjected to phenomenological explication. The remaining two protocols were used to support and clarify emergent meaning. A phenomenological explication of the data revealed a number of salient metaphors and themes. Upon being diagnosed with HIV, individuals were confronted with a socially and institutionally prescribed understanding of the disease; HIV as synonymous with AIDS and immediate death, HIV as sexual deviance, and HIV as myth. These metaphors influenced their conceptualisation and handling of HIV. Individual embodied metaphors included: embodying a heart of stone to live with HIV and perceiving HIV as a punishment from God, a demon from the Devil, a death sentence and a torture. Affectively, the experience of HIV was constituted as fear of physical disfigurement and exposure, anxiety, vulnerability, anger, betrayal, injustice and isolation. In a process of resolution and transformation, individuals imbibed positive metaphors with which to continue living with HIV. In order to cope with HIV, individuals seemed to negotiate a metaphorical space in which to dwell with their virus. This entailed establishing some form of dialogue with HIV or a Higher Power. This study revealed that metaphorical thinking about HIV /AIDS has a powerful impact on individuals' embodiment of their world. Metaphor is also an effective means Clf conveying and eliciting meaning in the experience of illness. Based upon these findings, it was suggested that metaphor be a prime focus for future research endeavours.
- Full Text:
Homogenous and heterogenous catalytic activity of metallophthalocyanines towards electrochemical detection of organic compounds
- Authors: Mafatle, Tsukutlane J P
- Date: 1998
- Subjects: Electrochemistry , Organic compounds , Phenols
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4316 , http://hdl.handle.net/10962/d1004974 , Electrochemistry , Organic compounds , Phenols
- Description: Cysteine plays an important role in many biological and pharmaceutical systems. Therefore, in view of its importance, it is essential to find means of detecting it at the lowest possible levels. In this regard, electrochemical techniques have been found to be capable of detecting analytes even at micro levels. However, electrochemical determination of cysteine occurs at a very high potentials. These overpotentials makes quantitative analysis or detection of cysteine difficult at most conventional carbon electrodes. On platinum electrode, the oxidation of cysteine has been reported to occur in the potential range 0.7 to 1.45 V (vs NHE). Therefore, the object of this investigative study has been to find an active complex that could replace platinum and other expensive metals as electrodes. Such a complex should also be capable of reducing the potential at which the oxidation of cysteine occurs on carbon electrodes. As a result, this manuscript gives a full report on the investigative study of electrocatalytic activity of molybdenum phthalocyanine complexes towards detection of cysteine. Molybdenum phthalocyanine, OMo(OH)Pc, and its tetrasulfonated derivative, [OMo(OH)TSPc]⁴⁻ were successfully used to reduce the potential needed to initiate the oxidation of cysteine on carbon paste electrodes (CPE). The oxidation of cysteine on CPE modified with [OMo(OH)Pc]⁴⁻ was found to occur at 0.29 V (vs Ag/AgCl), and in the presence of [OMo(OH)TSPc]⁴⁻ species in solution the oxidation occurred at 0.33 V (vs Ag/AgCl). Molybdenum, in the oxidation states of Mo(IV), Mo(V) and Mo(VI), is found in biological systems as an essential trace element, participating in a number of enzymatic reactions, where it is believed to be coordinated to sulphur-containing ligands in many molybdenum enzymes. This therefore explains why molybdenum phthalocyanines were employed in electroanalytical detection of sulphur containing amino acid, cysteine. Electrochemical methods have also been successfully used in detection of environmental pollutants such as phenolic compounds. Phenolic compounds are oxidised at readily accessible potentials. However, like cysteine, there are problems associated with the electrochemical detection of these important environmental pollutants. Their electrooxidation is known to form dimeric and/or polymeric oxidation products which adsorb onto the electrode surface, thus -videactivating it. Therefore, to address this problem, cobalt phthalocyanine (CoPc) and its tetrasulfonated derivative, [CoTSPc]⁴⁻ were employed in electrocatalytic detection of phenolic compounds. These complexes were found to increase the anodic peak currents for the oxidation of o-cresol, m-cresol, p-cresol, phenol, 2-chlorophenol and 4-chlorophenol. In addition, CoPc deposited onto the glassy carbon electrode improved the stability of the electrode, by reducing electrode poisoning caused by the electrooxidation products of the mentioned phenolic compounds. The potential at which the oxidation occurred and the current response of individual phenolic compounds depended on the degree of substitution and the type of substituent on the phenol molecule. In general, the current response was found to be lower for chlorinated phenols compared with the cresols and phenol. To establish the role of the central metal in the catalytic process, comparison of the electrocatalytic activity of some of the first row transition metal phthalocyanines, for the detection of mono-substituted phenolic compounds, showed the following trend: Co⁽¹¹⁾ > Mn⁽¹¹⁾ > Fe⁽¹¹⁾Pc > Ni⁽¹¹⁾Pc > Cu⁽¹¹⁾Pc > H₂Pc > Zn⁽¹¹⁾Pc > Bare GCE. A report is also given on electrocatalysis using [CoTSPc]⁴⁻ electrochemically deposited on the glassy carbon electrode. This was also found to enhance the anodic peak currents for the oxidation of all phenolic compounds. A report on the effects of scan rate, operating potential, analyte concentration and other variables is also given.
- Full Text:
- Authors: Mafatle, Tsukutlane J P
- Date: 1998
- Subjects: Electrochemistry , Organic compounds , Phenols
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4316 , http://hdl.handle.net/10962/d1004974 , Electrochemistry , Organic compounds , Phenols
- Description: Cysteine plays an important role in many biological and pharmaceutical systems. Therefore, in view of its importance, it is essential to find means of detecting it at the lowest possible levels. In this regard, electrochemical techniques have been found to be capable of detecting analytes even at micro levels. However, electrochemical determination of cysteine occurs at a very high potentials. These overpotentials makes quantitative analysis or detection of cysteine difficult at most conventional carbon electrodes. On platinum electrode, the oxidation of cysteine has been reported to occur in the potential range 0.7 to 1.45 V (vs NHE). Therefore, the object of this investigative study has been to find an active complex that could replace platinum and other expensive metals as electrodes. Such a complex should also be capable of reducing the potential at which the oxidation of cysteine occurs on carbon electrodes. As a result, this manuscript gives a full report on the investigative study of electrocatalytic activity of molybdenum phthalocyanine complexes towards detection of cysteine. Molybdenum phthalocyanine, OMo(OH)Pc, and its tetrasulfonated derivative, [OMo(OH)TSPc]⁴⁻ were successfully used to reduce the potential needed to initiate the oxidation of cysteine on carbon paste electrodes (CPE). The oxidation of cysteine on CPE modified with [OMo(OH)Pc]⁴⁻ was found to occur at 0.29 V (vs Ag/AgCl), and in the presence of [OMo(OH)TSPc]⁴⁻ species in solution the oxidation occurred at 0.33 V (vs Ag/AgCl). Molybdenum, in the oxidation states of Mo(IV), Mo(V) and Mo(VI), is found in biological systems as an essential trace element, participating in a number of enzymatic reactions, where it is believed to be coordinated to sulphur-containing ligands in many molybdenum enzymes. This therefore explains why molybdenum phthalocyanines were employed in electroanalytical detection of sulphur containing amino acid, cysteine. Electrochemical methods have also been successfully used in detection of environmental pollutants such as phenolic compounds. Phenolic compounds are oxidised at readily accessible potentials. However, like cysteine, there are problems associated with the electrochemical detection of these important environmental pollutants. Their electrooxidation is known to form dimeric and/or polymeric oxidation products which adsorb onto the electrode surface, thus -videactivating it. Therefore, to address this problem, cobalt phthalocyanine (CoPc) and its tetrasulfonated derivative, [CoTSPc]⁴⁻ were employed in electrocatalytic detection of phenolic compounds. These complexes were found to increase the anodic peak currents for the oxidation of o-cresol, m-cresol, p-cresol, phenol, 2-chlorophenol and 4-chlorophenol. In addition, CoPc deposited onto the glassy carbon electrode improved the stability of the electrode, by reducing electrode poisoning caused by the electrooxidation products of the mentioned phenolic compounds. The potential at which the oxidation occurred and the current response of individual phenolic compounds depended on the degree of substitution and the type of substituent on the phenol molecule. In general, the current response was found to be lower for chlorinated phenols compared with the cresols and phenol. To establish the role of the central metal in the catalytic process, comparison of the electrocatalytic activity of some of the first row transition metal phthalocyanines, for the detection of mono-substituted phenolic compounds, showed the following trend: Co⁽¹¹⁾ > Mn⁽¹¹⁾ > Fe⁽¹¹⁾Pc > Ni⁽¹¹⁾Pc > Cu⁽¹¹⁾Pc > H₂Pc > Zn⁽¹¹⁾Pc > Bare GCE. A report is also given on electrocatalysis using [CoTSPc]⁴⁻ electrochemically deposited on the glassy carbon electrode. This was also found to enhance the anodic peak currents for the oxidation of all phenolic compounds. A report on the effects of scan rate, operating potential, analyte concentration and other variables is also given.
- Full Text:
How green is our future? Thor Chemicals: a case study in South African environmental policy
- Authors: Flint, Adrian
- Date: 1998
- Subjects: Environmental ethics , Environmental policy -- South Africa , Environmental policy -- South Africa -- Case studies , Environmental degradation -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2776 , http://hdl.handle.net/10962/d1002986 , Environmental ethics , Environmental policy -- South Africa , Environmental policy -- South Africa -- Case studies , Environmental degradation -- South Africa
- Description: This study focuses on South African Environmefltal policy; in particular its policies regarding hazardous waste. These policies are addressed within the framework of a case study which serves as basis to critically evaluate government environmental policies both past and present. The thesis examines South African environmental policy against the backdrop of competing schools of thought regarding the relationship between growth and development on the one hand and long term environmental security on the other. Development strategies such as Sustainable Development and the government's Growth, Employment and Redistribution as well as philosophies such as Deep Ecology will be discussed. The thesis argues that Non-Governmental Organisations are the holders of a real environmental ethic and thus their role in preventing environmental degradation is of critical importance. Furthermore, it is imperative that this ethic be disseminated across society if South Africa is to successfully pursue sound environmental policies. This argument is pursued by way of a case study, Thor Chemicals: a company responsible for the running of the largest mercury recovery facility in the world. This plant, which operated in Cato Ridge, KwaZulu-Natal, has been the source of much controversy since it was found that many of its employees and ex-employees were suffering from severe mercury poisoning resulting in two fatalities. The company was also involved in the importation of hazardous wastes as well as the pollution of the surrounding environment. Thor is currently the subject of inquiry by the government-appointed Davis Commission. It is pointed out that ill the past South Africa held no real environmental ethic and environmental degradation ensued as a result. The presented thesis argues that, despite assurances to the contrary, the present government is also without a true environmental ethic that will be effective in preventing future degradation.
- Full Text:
- Authors: Flint, Adrian
- Date: 1998
- Subjects: Environmental ethics , Environmental policy -- South Africa , Environmental policy -- South Africa -- Case studies , Environmental degradation -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2776 , http://hdl.handle.net/10962/d1002986 , Environmental ethics , Environmental policy -- South Africa , Environmental policy -- South Africa -- Case studies , Environmental degradation -- South Africa
- Description: This study focuses on South African Environmefltal policy; in particular its policies regarding hazardous waste. These policies are addressed within the framework of a case study which serves as basis to critically evaluate government environmental policies both past and present. The thesis examines South African environmental policy against the backdrop of competing schools of thought regarding the relationship between growth and development on the one hand and long term environmental security on the other. Development strategies such as Sustainable Development and the government's Growth, Employment and Redistribution as well as philosophies such as Deep Ecology will be discussed. The thesis argues that Non-Governmental Organisations are the holders of a real environmental ethic and thus their role in preventing environmental degradation is of critical importance. Furthermore, it is imperative that this ethic be disseminated across society if South Africa is to successfully pursue sound environmental policies. This argument is pursued by way of a case study, Thor Chemicals: a company responsible for the running of the largest mercury recovery facility in the world. This plant, which operated in Cato Ridge, KwaZulu-Natal, has been the source of much controversy since it was found that many of its employees and ex-employees were suffering from severe mercury poisoning resulting in two fatalities. The company was also involved in the importation of hazardous wastes as well as the pollution of the surrounding environment. Thor is currently the subject of inquiry by the government-appointed Davis Commission. It is pointed out that ill the past South Africa held no real environmental ethic and environmental degradation ensued as a result. The presented thesis argues that, despite assurances to the contrary, the present government is also without a true environmental ethic that will be effective in preventing future degradation.
- Full Text:
Human rights: an investigation into the importance of second generation rights
- Authors: Bentley, Kristina Anne
- Date: 1998
- Subjects: Human rights -- Philosophy , Human rights
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2759 , http://hdl.handle.net/10962/d1002969 , Human rights -- Philosophy , Human rights
- Description: This study examines the notion of universal human rights in the context of the importance of social and economic rights for the agency and dignity of human beings. It argues that the recognition of basic rights to what is necessary for physical well-being is essential to any adequate theory of human rights, and that rights of the civil and political variety depend on the recognition of social and economic rights if they are to be exercised. Therefore the secondary status which is usually accorded to social and economic rights results in an imbalanced ideal of human rights both in theory and in practice. This study is an attempt to place second generation rights in their proper context and to argue for them as human rights of equal status and importance. It focuses on the derivation of human rights in general, and shows that second generation rights may be accommodated within this structure. It further supports this position by showing that the categorical differences which are asserted to exist between first and second generation rights are based on a mistaken conception of positive and negative rights and duties, as well as an inadequate conception of liberty. The thesis shows that all rights generate a variety of duties, both positive and negative, and that an adequate theory of rights has to be able to accommodate the inevitability of conflicts of rights at the level of their enforcement. Consequently, this study argues there is no reason to give either class of right primary importance, as both first and second generation human rights are essential to the agency and dignity of a human being, and they are thus interdependent. Furthermore, the thesis shows that human rights can be balanced at the level of the obligations which they generate without compromising the deontological nature of such rights. This thesis argues that a theory of rights which is rooted in the liberal democratic notion of rights, such as that characterised by the choice theory of rights, is inadequate. It therefore argues that a benefit theory of rights must be adopted in order to accommodate conflicts of rights when they arise. The thesis argues that as such conflicts of rights are" most common in cases involving the assertion of social and economic rights, this balancing of rights is of special significance for the enforcement of second generation rights. Furthermore, this thesis argues for a theory of minimal interdependence of first and second generation rights, in order to accommodate the notion of first and second generation rights of equal status and importance, as well as to prevent an inflation of rights claims which would compromise the balancing of rights. It is argued that a reordering of values is necessary to take account of material well-being, as well as civil freedom, as both of these generate fundamental rights of equal status and importance.
- Full Text:
- Authors: Bentley, Kristina Anne
- Date: 1998
- Subjects: Human rights -- Philosophy , Human rights
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2759 , http://hdl.handle.net/10962/d1002969 , Human rights -- Philosophy , Human rights
- Description: This study examines the notion of universal human rights in the context of the importance of social and economic rights for the agency and dignity of human beings. It argues that the recognition of basic rights to what is necessary for physical well-being is essential to any adequate theory of human rights, and that rights of the civil and political variety depend on the recognition of social and economic rights if they are to be exercised. Therefore the secondary status which is usually accorded to social and economic rights results in an imbalanced ideal of human rights both in theory and in practice. This study is an attempt to place second generation rights in their proper context and to argue for them as human rights of equal status and importance. It focuses on the derivation of human rights in general, and shows that second generation rights may be accommodated within this structure. It further supports this position by showing that the categorical differences which are asserted to exist between first and second generation rights are based on a mistaken conception of positive and negative rights and duties, as well as an inadequate conception of liberty. The thesis shows that all rights generate a variety of duties, both positive and negative, and that an adequate theory of rights has to be able to accommodate the inevitability of conflicts of rights at the level of their enforcement. Consequently, this study argues there is no reason to give either class of right primary importance, as both first and second generation human rights are essential to the agency and dignity of a human being, and they are thus interdependent. Furthermore, the thesis shows that human rights can be balanced at the level of the obligations which they generate without compromising the deontological nature of such rights. This thesis argues that a theory of rights which is rooted in the liberal democratic notion of rights, such as that characterised by the choice theory of rights, is inadequate. It therefore argues that a benefit theory of rights must be adopted in order to accommodate conflicts of rights when they arise. The thesis argues that as such conflicts of rights are" most common in cases involving the assertion of social and economic rights, this balancing of rights is of special significance for the enforcement of second generation rights. Furthermore, this thesis argues for a theory of minimal interdependence of first and second generation rights, in order to accommodate the notion of first and second generation rights of equal status and importance, as well as to prevent an inflation of rights claims which would compromise the balancing of rights. It is argued that a reordering of values is necessary to take account of material well-being, as well as civil freedom, as both of these generate fundamental rights of equal status and importance.
- Full Text:
Identity and transformation within the Playhouse Dance Company, 1993-1997
- Ballantyne, Tammy Marguerite
- Authors: Ballantyne, Tammy Marguerite
- Date: 1998
- Subjects: Playhouse dance company , Dance -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2131 , http://hdl.handle.net/10962/d1002363 , Playhouse dance company , Dance -- South Africa
- Description: This thesis examines the principles and policies underlying the need for transformation within the Playhouse Dance Company (PDC) in Durban and the actualities of implementing these visions and procedures. It is proposed that artistic structures, ideals and processes cannot remain impervious to the climate of change. Alterations in the political arena demand radical permutations within arts councils and their concept of repertoire, educational programmes and training. Transformation is linked to the problem of identity and it is suggested that the company is in the midst of a journey towards "becoming" rather than "being". Chapter One comprises an overview of changing trends in the arts globally and the impact on South Mrican art forms and processes. There is also an examination of the past, the establishment of arts councils and the colonial heritage of the dance companies within these councils. The formative years of the NAP AC Dance Company and the strategies formulated by former artistic directors have, it is suggested, hampered the transformation process. Chapter Two focuses on the PDC's endeavours to transform between the years 1993 and 1997. Lack of funding, conservative public tastes and training processes are. all' issues confronting management, choreographers, educators and performers in attempting to provide a clear direction towards transformation. The company walk a tightrope as they struggle to balance the heritage of their artistic past while giving birth to a new heritage for the future. Chapter Three discusses two areas that reveal measurable attempts at transformation. Hawkins offers re-inventions of the classics which encourages innovation, and Siwela Sonke was conceived to draw on dance forms located in Kwazulu-Natal in the search for a South Mrican dance aesthetic. Chapter Four investigates whether transformative visions are becoming a reality and suggests how the company could extend the process further. This chapter concludes with .. ideas about the nature of culture and how this informs,the exercise of transformation. This thesis proposes that transformation within the PDC is occurring even though it has its shortcomings. The main thrust of the research is to investigate, identifY and document factors that are contributing to current dance trends in Durban.
- Full Text:
- Authors: Ballantyne, Tammy Marguerite
- Date: 1998
- Subjects: Playhouse dance company , Dance -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2131 , http://hdl.handle.net/10962/d1002363 , Playhouse dance company , Dance -- South Africa
- Description: This thesis examines the principles and policies underlying the need for transformation within the Playhouse Dance Company (PDC) in Durban and the actualities of implementing these visions and procedures. It is proposed that artistic structures, ideals and processes cannot remain impervious to the climate of change. Alterations in the political arena demand radical permutations within arts councils and their concept of repertoire, educational programmes and training. Transformation is linked to the problem of identity and it is suggested that the company is in the midst of a journey towards "becoming" rather than "being". Chapter One comprises an overview of changing trends in the arts globally and the impact on South Mrican art forms and processes. There is also an examination of the past, the establishment of arts councils and the colonial heritage of the dance companies within these councils. The formative years of the NAP AC Dance Company and the strategies formulated by former artistic directors have, it is suggested, hampered the transformation process. Chapter Two focuses on the PDC's endeavours to transform between the years 1993 and 1997. Lack of funding, conservative public tastes and training processes are. all' issues confronting management, choreographers, educators and performers in attempting to provide a clear direction towards transformation. The company walk a tightrope as they struggle to balance the heritage of their artistic past while giving birth to a new heritage for the future. Chapter Three discusses two areas that reveal measurable attempts at transformation. Hawkins offers re-inventions of the classics which encourages innovation, and Siwela Sonke was conceived to draw on dance forms located in Kwazulu-Natal in the search for a South Mrican dance aesthetic. Chapter Four investigates whether transformative visions are becoming a reality and suggests how the company could extend the process further. This chapter concludes with .. ideas about the nature of culture and how this informs,the exercise of transformation. This thesis proposes that transformation within the PDC is occurring even though it has its shortcomings. The main thrust of the research is to investigate, identifY and document factors that are contributing to current dance trends in Durban.
- Full Text:
Improvement of fertility and hatchability of artificially incubated ostrich eggs in the little Karoo
- Van Schalkwyk, Salmon Jacobus
- Authors: Van Schalkwyk, Salmon Jacobus
- Date: 1998
- Subjects: Ostrich farming -- South Africa , Eggs -- Hatchability , Eggs -- Incubation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5713 , http://hdl.handle.net/10962/d1005399
- Description: Ostriches are an important commercial species in South Africa and are becoming increasingly so in other parts of the world. Fertility and hatchability of artificially incubated ostrich eggs, however, is generally regarded as low compared to other poultry species and to ostriches in the wild. Investigation into specific farming practices at present indicated scope for an overall improvement in productivity through a sound breeding strategy. This thesis investigated factors that affect egg production, fertility, and hatchability of artificially incubated eggs in the Little Karoo region of South Africa. Specific breeding pair combinations accounted for the major variations in egg weight, hatchability, chick production and offspring weight at slaughter age. An appreciable proportion of variation in reproductive traits was attributable to the repeatable nature of breeding pair performance from year to year, even from first breeding attempts, suggesting that selection of good breeding stock can be made from an early age. Artificially incubated eggs showed improved hatchability when eggs were collected two to three hours after lay rather than the following morning. Storing position of eggs did not significantly effect hatchability when eggs were stored for a maximum of one week. The critical zero temperature for ostrich eggs, below which no embryonical development takes place, was found to be ± 25°C and cooling eggs to temperatures below 20°C for complete cessation of embryonic development during storage resulted in better hatchabilities compared to eggs stored at 25°C room temperature. Hatchability decreased when incubator temperatures were raised from 36 to 37.3°C. Large temperature fluctuations and gradients, which encompass detrimental temperatures, persist within forced draught wooden incubators of the type most commonly in use in the Little Karoo region. The highest temperatures occurred at the top of these incubators and will consequently have a negative impact on hatchability. The ontogeny of ostrich egg metabolism showed an exponential increase during the first 70% of incubation followed by a decline to 75% of the peak value between days 31 and 38 of incubation. From peak levels of embryonic development it was calculated that single stage incubators needs an airflow of 54.4 1/egg.hour to maintain oxygen levels just below 21% and carbon dioxide levels below 0.5%. Lower embryonic mortalities were observed when eggs were turned twenty-four times/day in an electronic incubator compared to hand turning twice a day. Eggs rotated through increasing angles between 60 and 90° resulted in a linear improvement in hatchability. In incubators where turning angles were fixed at 60°, lower hatchabilities were overcome by incubating eggs for 2 - 3 weeks in a horizontal position before placing them vertically. No specific farming practice could be singled out as the main cause of low fertility or hatchability but rather a combination of certain practices applied wrongly.
- Full Text:
Improvement of fertility and hatchability of artificially incubated ostrich eggs in the little Karoo
- Authors: Van Schalkwyk, Salmon Jacobus
- Date: 1998
- Subjects: Ostrich farming -- South Africa , Eggs -- Hatchability , Eggs -- Incubation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5713 , http://hdl.handle.net/10962/d1005399
- Description: Ostriches are an important commercial species in South Africa and are becoming increasingly so in other parts of the world. Fertility and hatchability of artificially incubated ostrich eggs, however, is generally regarded as low compared to other poultry species and to ostriches in the wild. Investigation into specific farming practices at present indicated scope for an overall improvement in productivity through a sound breeding strategy. This thesis investigated factors that affect egg production, fertility, and hatchability of artificially incubated eggs in the Little Karoo region of South Africa. Specific breeding pair combinations accounted for the major variations in egg weight, hatchability, chick production and offspring weight at slaughter age. An appreciable proportion of variation in reproductive traits was attributable to the repeatable nature of breeding pair performance from year to year, even from first breeding attempts, suggesting that selection of good breeding stock can be made from an early age. Artificially incubated eggs showed improved hatchability when eggs were collected two to three hours after lay rather than the following morning. Storing position of eggs did not significantly effect hatchability when eggs were stored for a maximum of one week. The critical zero temperature for ostrich eggs, below which no embryonical development takes place, was found to be ± 25°C and cooling eggs to temperatures below 20°C for complete cessation of embryonic development during storage resulted in better hatchabilities compared to eggs stored at 25°C room temperature. Hatchability decreased when incubator temperatures were raised from 36 to 37.3°C. Large temperature fluctuations and gradients, which encompass detrimental temperatures, persist within forced draught wooden incubators of the type most commonly in use in the Little Karoo region. The highest temperatures occurred at the top of these incubators and will consequently have a negative impact on hatchability. The ontogeny of ostrich egg metabolism showed an exponential increase during the first 70% of incubation followed by a decline to 75% of the peak value between days 31 and 38 of incubation. From peak levels of embryonic development it was calculated that single stage incubators needs an airflow of 54.4 1/egg.hour to maintain oxygen levels just below 21% and carbon dioxide levels below 0.5%. Lower embryonic mortalities were observed when eggs were turned twenty-four times/day in an electronic incubator compared to hand turning twice a day. Eggs rotated through increasing angles between 60 and 90° resulted in a linear improvement in hatchability. In incubators where turning angles were fixed at 60°, lower hatchabilities were overcome by incubating eggs for 2 - 3 weeks in a horizontal position before placing them vertically. No specific farming practice could be singled out as the main cause of low fertility or hatchability but rather a combination of certain practices applied wrongly.
- Full Text:
In search of the culture of links : the use of myth and ritual in the work of Peter Brook
- Authors: Du Plessis, Tanya Lenore
- Date: 1998
- Subjects: Brook, Peter -- Criticism and interpretation , Myth in literature , Mahābhārata -- Adaptations , Ritual in literature
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2136 , http://hdl.handle.net/10962/d1002368 , Brook, Peter -- Criticism and interpretation , Myth in literature , Mahābhārata -- Adaptations , Ritual in literature
- Description: This thesis examines the use of elements of myth and ritual in the work of Peter Brook, focusing primarily on The Mahabharata ( 1986 ). The argument proposes that Brook uses myth and ritual as an integral part of his search for the culture of links .. This thesis examines the precise functioning of myth and ritual in Brook's theatre, and places his work in relation to the concepts of interculturalism and postmodernism. In so doing, The Mahabharata is seen as a valid and important step in Brook's search for the culture of links. Chapter One formulates broad-based concepts of myth and ritual, and examines their function in society and culture, as well as their role in theatre. Chapter Two offers a brief discussion of the use of elements of myth and ritual in Brook's productions, beginning with King Lear (1962), and ending with 0rghast (1971). The discussion illustrates the multiple functions which myth and ritual serve in Brook's work. Chapter Three examines the trend of interculturalism, placing Brook's work within this franlework. Attention is given to the moral and political issues implicit in interculturalism. The chapter highlights the need for intercultural theatre to be evaluated in terms of artistic criteria, rather than on anthropological or political grounds. Finally, there is a discussion of the work of other intercultural theatre practitioners. Chapter Four examines Brook's Mahabharata. A detailed discussion of the authenticity and visual presentation of Brook's interpretation shows how Brook mediates between the Indian epic and a Western audience An examination of the critical response offers insights into the dangers of insensitive cross-cultural contact.. Chapter Five offers a critical summary of the argument. Brook's search for the culture of links has led him to use elements of myths and rituals of non-Western cultures. In so doing, Brook seeks to bring their living quality to his work, and to forge links between the peoples and cultures of the world.
- Full Text:
- Authors: Du Plessis, Tanya Lenore
- Date: 1998
- Subjects: Brook, Peter -- Criticism and interpretation , Myth in literature , Mahābhārata -- Adaptations , Ritual in literature
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2136 , http://hdl.handle.net/10962/d1002368 , Brook, Peter -- Criticism and interpretation , Myth in literature , Mahābhārata -- Adaptations , Ritual in literature
- Description: This thesis examines the use of elements of myth and ritual in the work of Peter Brook, focusing primarily on The Mahabharata ( 1986 ). The argument proposes that Brook uses myth and ritual as an integral part of his search for the culture of links .. This thesis examines the precise functioning of myth and ritual in Brook's theatre, and places his work in relation to the concepts of interculturalism and postmodernism. In so doing, The Mahabharata is seen as a valid and important step in Brook's search for the culture of links. Chapter One formulates broad-based concepts of myth and ritual, and examines their function in society and culture, as well as their role in theatre. Chapter Two offers a brief discussion of the use of elements of myth and ritual in Brook's productions, beginning with King Lear (1962), and ending with 0rghast (1971). The discussion illustrates the multiple functions which myth and ritual serve in Brook's work. Chapter Three examines the trend of interculturalism, placing Brook's work within this franlework. Attention is given to the moral and political issues implicit in interculturalism. The chapter highlights the need for intercultural theatre to be evaluated in terms of artistic criteria, rather than on anthropological or political grounds. Finally, there is a discussion of the work of other intercultural theatre practitioners. Chapter Four examines Brook's Mahabharata. A detailed discussion of the authenticity and visual presentation of Brook's interpretation shows how Brook mediates between the Indian epic and a Western audience An examination of the critical response offers insights into the dangers of insensitive cross-cultural contact.. Chapter Five offers a critical summary of the argument. Brook's search for the culture of links has led him to use elements of myths and rituals of non-Western cultures. In so doing, Brook seeks to bring their living quality to his work, and to forge links between the peoples and cultures of the world.
- Full Text:
Managing natural resources in a rural settlement in Peddie district
- Authors: Ainslie, Andrew
- Date: 1998
- Subjects: Conservation of natural resources -- South Africa -- Management , Natural resources -- South Africa -- Peddie District -- Management , Peddie (South Africa) -- Social conditions , Peddie (South Africa) -- History
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2110 , http://hdl.handle.net/10962/d1007462 , Conservation of natural resources -- South Africa -- Management , Natural resources -- South Africa -- Peddie District -- Management , Peddie (South Africa) -- Social conditions , Peddie (South Africa) -- History
- Description: This thesis is an account of the challenges people in Tyefu Location, Peddie District, and specifically in Gwabeni village, face in their attempts to manage their common pool natural resources. Taking my analytical cue from the literature which deals with the institutional dimensions of resource management in common property systems, I look at the impact of both outside influences and local dynamics on resource managing institutions at village level. I show how particular historical circumstances, including state interventions, led to the enclosure of Tyefu Location, and to the rapid increase in the population that had to be accommodated here. This placed enormous pressure on the natural resources of the area, and contributed to the emasculation of the local institutions responsible for overseeing resource management. The residents of the location adopted whatever strategies they could to ameliorate the depletion of natural resources in their villages. One 'traditional' strategy they have sought to emulate is to move their imizi (homesteads) away from areas where local resources has been exhausted. Given the finite area of land available to them, this strategy was only ever likely to be successful in the short-term. I analyse social, economic and institutional factors at village level that appear to act as disincentives to collective resource management activities. These factors include the social structure of the imizi and the socio-economic heterogeneity that exists between imizi in Gwabeni village. The varying degrees of household economic marginality that follow from this, together with the differential ownership of livestock and other possessions that decrease people's reliance on locally available natural resources, mean that the transaction costs that people would incur by contributing to collective resource management activities, differ widely. A primary cause of people's failure to engage in resource management at village level stems from the dispersion of the members of their imizi. This factor robs the village of decision makers and undermines the capacity of those left behind to make and implement resource management decisions. It results in the various members of imizi in the village having different orientations that dissipate the energy needed for collective action. It also fuels existing struggles, and creates new ones, over the meanings and uses of the term 'community'. I conclude by arguing that, in Tyefu Location, the management of natural resources is extremely difficult to co-ordinate, because such management is highly contested, undermined by differentiation among resource users, and subject to the attentions of weak village institutions that do not share a clear set of resource management objectives. , KMBT_363
- Full Text:
- Authors: Ainslie, Andrew
- Date: 1998
- Subjects: Conservation of natural resources -- South Africa -- Management , Natural resources -- South Africa -- Peddie District -- Management , Peddie (South Africa) -- Social conditions , Peddie (South Africa) -- History
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2110 , http://hdl.handle.net/10962/d1007462 , Conservation of natural resources -- South Africa -- Management , Natural resources -- South Africa -- Peddie District -- Management , Peddie (South Africa) -- Social conditions , Peddie (South Africa) -- History
- Description: This thesis is an account of the challenges people in Tyefu Location, Peddie District, and specifically in Gwabeni village, face in their attempts to manage their common pool natural resources. Taking my analytical cue from the literature which deals with the institutional dimensions of resource management in common property systems, I look at the impact of both outside influences and local dynamics on resource managing institutions at village level. I show how particular historical circumstances, including state interventions, led to the enclosure of Tyefu Location, and to the rapid increase in the population that had to be accommodated here. This placed enormous pressure on the natural resources of the area, and contributed to the emasculation of the local institutions responsible for overseeing resource management. The residents of the location adopted whatever strategies they could to ameliorate the depletion of natural resources in their villages. One 'traditional' strategy they have sought to emulate is to move their imizi (homesteads) away from areas where local resources has been exhausted. Given the finite area of land available to them, this strategy was only ever likely to be successful in the short-term. I analyse social, economic and institutional factors at village level that appear to act as disincentives to collective resource management activities. These factors include the social structure of the imizi and the socio-economic heterogeneity that exists between imizi in Gwabeni village. The varying degrees of household economic marginality that follow from this, together with the differential ownership of livestock and other possessions that decrease people's reliance on locally available natural resources, mean that the transaction costs that people would incur by contributing to collective resource management activities, differ widely. A primary cause of people's failure to engage in resource management at village level stems from the dispersion of the members of their imizi. This factor robs the village of decision makers and undermines the capacity of those left behind to make and implement resource management decisions. It results in the various members of imizi in the village having different orientations that dissipate the energy needed for collective action. It also fuels existing struggles, and creates new ones, over the meanings and uses of the term 'community'. I conclude by arguing that, in Tyefu Location, the management of natural resources is extremely difficult to co-ordinate, because such management is highly contested, undermined by differentiation among resource users, and subject to the attentions of weak village institutions that do not share a clear set of resource management objectives. , KMBT_363
- Full Text:
Media reach and reception in development communication: the case of the Rural Industries Innovation Centre in Botswana
- Authors: Maleke, Jackson Mogopodi
- Date: 1998
- Subjects: Rural Industries Innovation Centre (Kanye, Botswana) , Communication in rural development , Mass media in community development
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3455 , http://hdl.handle.net/10962/d1002909 , Rural Industries Innovation Centre (Kanye, Botswana) , Communication in rural development , Mass media in community development
- Description: The study was conducted in Phitshane-Molopo in Botswana. Phitshane-Molopo is located about 115 kilometers south of the main village of Kanye in which the Rural Industries Innovation Centre operates. The study constitutes the first attempt at evaluating audience reach and reception of the RIIC media messages. In this study, a sample of 50 representatives of households (the rationale is covered in chapter 1) was taken, for which a questionnaire was administered, including conducting in-depth interviews with key informants. The study found that RIlC media are not reaching the audience in keeping with the corporate goals and assumptions on the basis of which the communication strategy was established. The audience has claimed that the print media relayed to them through the extension officer channel do not reach them. The study also found that the audience possessed adequate literacy skills and the majority of them could read materials produced in Setswana. Only a few individuals preferred media text produced in the English language. The study therefore deplores RIIC's proclivity towards producing its media texts only in the English language. This has tended to marginalise members of the audience who cannot read in English. It is thus hoped that this study would provide a learning experience for RIIC to consider producing its communication media in relation to the needs of the audience. The study also found that the impact of the RIIC radio programme is very poor, with only a low of 2% of the sample population having listened to this programme. The problem stems from the poor Radio Botswana transmission system. The audience said that for the larger part of the day, they can't get Radio Botswana on air. As a result, they have shifted their interest to the South African radio stations such as Radio Tswana and Radio Mmabatho, which are constantly on air. The study concludes that the RIIC communication strategy is failing in the study area because the paradigm in which it is located is somewhat flawed, as a result of which it does not effectively impact upon reach and reception. At the core of this failure rate are implementation problems and the lack of evaluation that would have picked up the - problems earlier, for which solutions would have been found. Consequently, th~$tudy recommends the need to explore the suitability and effectiveness of the indigenous media for possible syncretization with conventional media as recommended in the need based integrative model (Nwosu and Megwa: 1993). Indigenous media are ideally suited to rural communication needs because they are consistent with the socio-cultural expectations of the audience. RIIC therefore stands to benefit from these media because the bulk of its audience resides in rural areas.
- Full Text:
- Authors: Maleke, Jackson Mogopodi
- Date: 1998
- Subjects: Rural Industries Innovation Centre (Kanye, Botswana) , Communication in rural development , Mass media in community development
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3455 , http://hdl.handle.net/10962/d1002909 , Rural Industries Innovation Centre (Kanye, Botswana) , Communication in rural development , Mass media in community development
- Description: The study was conducted in Phitshane-Molopo in Botswana. Phitshane-Molopo is located about 115 kilometers south of the main village of Kanye in which the Rural Industries Innovation Centre operates. The study constitutes the first attempt at evaluating audience reach and reception of the RIIC media messages. In this study, a sample of 50 representatives of households (the rationale is covered in chapter 1) was taken, for which a questionnaire was administered, including conducting in-depth interviews with key informants. The study found that RIlC media are not reaching the audience in keeping with the corporate goals and assumptions on the basis of which the communication strategy was established. The audience has claimed that the print media relayed to them through the extension officer channel do not reach them. The study also found that the audience possessed adequate literacy skills and the majority of them could read materials produced in Setswana. Only a few individuals preferred media text produced in the English language. The study therefore deplores RIIC's proclivity towards producing its media texts only in the English language. This has tended to marginalise members of the audience who cannot read in English. It is thus hoped that this study would provide a learning experience for RIIC to consider producing its communication media in relation to the needs of the audience. The study also found that the impact of the RIIC radio programme is very poor, with only a low of 2% of the sample population having listened to this programme. The problem stems from the poor Radio Botswana transmission system. The audience said that for the larger part of the day, they can't get Radio Botswana on air. As a result, they have shifted their interest to the South African radio stations such as Radio Tswana and Radio Mmabatho, which are constantly on air. The study concludes that the RIIC communication strategy is failing in the study area because the paradigm in which it is located is somewhat flawed, as a result of which it does not effectively impact upon reach and reception. At the core of this failure rate are implementation problems and the lack of evaluation that would have picked up the - problems earlier, for which solutions would have been found. Consequently, th~$tudy recommends the need to explore the suitability and effectiveness of the indigenous media for possible syncretization with conventional media as recommended in the need based integrative model (Nwosu and Megwa: 1993). Indigenous media are ideally suited to rural communication needs because they are consistent with the socio-cultural expectations of the audience. RIIC therefore stands to benefit from these media because the bulk of its audience resides in rural areas.
- Full Text:
Morphometrics and preliminary biology of the caridean shrimp Nauticaris marionis Bate, 1888, at the Prince Edward Islands (South Ocean), 37° 50'E, 46° 45'S
- Authors: Kuun, Patrick John
- Date: 1998
- Subjects: Shrimps -- Prince Edward Islands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5733 , http://hdl.handle.net/10962/d1005419 , Shrimps -- Prince Edward Islands
- Description: Carapace length, as the best measure of N. marionis body size, is precisely defined. It is shown that N. marionis is a partially protandric hermaphrodite. N. marionis appear to hatch just before April each year, with a little hatching persisting until May. The vast majority of juveniles develop into males. The majority of males transmutate into females in their third year. By April/May the transmutation is probably complete. Reproduction can occur before all male secondary characteristics have been lost. A small minority of individuals develop directly into females without passing through a male phase. At least some of these females can be initially recognized after they have developed mature ovaries by the presence of appendices internae on their first pleopods, a male copulatory structure which all juvenile N. marionis possess. Too few gravid females were recovered to make any statement on whether spawning can occur before this structure is lost. Such females may lose their first pleopod appendices internae in one moult, possibly just before spawning, which may be in late April/early May. Such individuals seem to mature into ovigerous females at a slightly smaller carapace length than do the majority of females which have had a male-phase past. A few females which have passed through a male phase seem to begin developing ovaries at about this small carapace length as well. Once the appendices internae have been lost there appears to be no way of identifying any given female's past life-history. It would seem that during the first year of life N. marionis survive in undetected localities, moult into juveniles, and then settle amongst the benthos from the plankton. Diurnal vertical migration then occurs up to an unknown larger size. It is not known whether the larvae are initially planktonic or not. It is possible that settling of small N. marionis onto the benthos only begins after November. Whether the appendices masculinae of some males only begin growing after they have settled Abstract XIX onto the benthos is unknown, but for the majority at least this begins whilst they are planktonic juveniles. Individuals older than five years are undetectable using samples of the sizes analyzed in this thesis, but they may well persist until quite an advanced age. Niche separation between smaller and larger N. marionis individuals may occur. Diel vertical migration may occur to some extent amongst large N. marionis. Itinerant euphausiids may contribute substantially to the maintenance of top predator populations at the archipelago, either through direct predation by those predators or via predation by N. marionis, which in turn are consumed by those predators. N. marionis itself is an opportunistic feeder, although the majority of its prey seem to be suspension feeders, both benthic and pelagic. In multisample situations, ageing of N. marionis cohorts is made less subjective if one utilizes the phenomenon of synchronized sexual inversion. The von Bertalanffy growth parameters for N. marionis are tentatively identified as k = 0.2353/year, L_ = 12.69mm, to = -0.2828 years and WW_ = 2.03g. The programme FiSAT is discussed, having been found to be extremely useful, but having also been found to have certain faults. Various hypotheses are proposed and are put forward as suggestions for future studies.
- Full Text:
- Authors: Kuun, Patrick John
- Date: 1998
- Subjects: Shrimps -- Prince Edward Islands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5733 , http://hdl.handle.net/10962/d1005419 , Shrimps -- Prince Edward Islands
- Description: Carapace length, as the best measure of N. marionis body size, is precisely defined. It is shown that N. marionis is a partially protandric hermaphrodite. N. marionis appear to hatch just before April each year, with a little hatching persisting until May. The vast majority of juveniles develop into males. The majority of males transmutate into females in their third year. By April/May the transmutation is probably complete. Reproduction can occur before all male secondary characteristics have been lost. A small minority of individuals develop directly into females without passing through a male phase. At least some of these females can be initially recognized after they have developed mature ovaries by the presence of appendices internae on their first pleopods, a male copulatory structure which all juvenile N. marionis possess. Too few gravid females were recovered to make any statement on whether spawning can occur before this structure is lost. Such females may lose their first pleopod appendices internae in one moult, possibly just before spawning, which may be in late April/early May. Such individuals seem to mature into ovigerous females at a slightly smaller carapace length than do the majority of females which have had a male-phase past. A few females which have passed through a male phase seem to begin developing ovaries at about this small carapace length as well. Once the appendices internae have been lost there appears to be no way of identifying any given female's past life-history. It would seem that during the first year of life N. marionis survive in undetected localities, moult into juveniles, and then settle amongst the benthos from the plankton. Diurnal vertical migration then occurs up to an unknown larger size. It is not known whether the larvae are initially planktonic or not. It is possible that settling of small N. marionis onto the benthos only begins after November. Whether the appendices masculinae of some males only begin growing after they have settled Abstract XIX onto the benthos is unknown, but for the majority at least this begins whilst they are planktonic juveniles. Individuals older than five years are undetectable using samples of the sizes analyzed in this thesis, but they may well persist until quite an advanced age. Niche separation between smaller and larger N. marionis individuals may occur. Diel vertical migration may occur to some extent amongst large N. marionis. Itinerant euphausiids may contribute substantially to the maintenance of top predator populations at the archipelago, either through direct predation by those predators or via predation by N. marionis, which in turn are consumed by those predators. N. marionis itself is an opportunistic feeder, although the majority of its prey seem to be suspension feeders, both benthic and pelagic. In multisample situations, ageing of N. marionis cohorts is made less subjective if one utilizes the phenomenon of synchronized sexual inversion. The von Bertalanffy growth parameters for N. marionis are tentatively identified as k = 0.2353/year, L_ = 12.69mm, to = -0.2828 years and WW_ = 2.03g. The programme FiSAT is discussed, having been found to be extremely useful, but having also been found to have certain faults. Various hypotheses are proposed and are put forward as suggestions for future studies.
- Full Text:
Natural resources and local management in the Hewu District of the Eastern Cape : limitations to achieving sustainability
- Authors: Nkansa-Dwamena, Yaw
- Date: 1998
- Subjects: Natural resources -- South Africa -- Management , Natural resources -- South Africa -- Eastern Cape -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4218 , http://hdl.handle.net/10962/d1003787 , Natural resources -- South Africa -- Management , Natural resources -- South Africa -- Eastern Cape -- Management
- Description: The Mceula Commonage Land in the Hewu district lies due northwest of Whittle sea and west of Queenstown in the Eastern Cape. This thesis has two main objectives. Firstly, to survey and analyse the condition of the natural resource. base in the Hewu district with particular reference to water, soil, vegetation and land use. Secondly, to investigate the relationship between scientific approaches to assessing land use degradation and to compare these to the results obtained using a participatory approach of the rural environment of the Hewu district of the Eastern Cape. Random quadrats (4m2) were sampled and corresponding line transects were done with increasing distances from the villages. The Braun-Blanquet method was used to find the cover and abundance of the various species of plants. Data obtained from point sampling along 100 metre line transects was used to assess the condition of the veld using Trollope's technique. Six communities were defined using TWINSP AN, and grazing capacities and veld condition scores of the respective sites were calculated. It was concluded that the six communities were distributed along a gradient of palatable to non palatable grass and grasslike species. Rangelands close to the villages had low veld condition scores and percentage plant cover as opposed to those farther away from the villages. The null hypothesis of no significant difference between the percentage plant cover and condition of the veld close to the villages and farther away from the villages was rejected. Whilst it is urgent to resolve political disputes around land through land distribution, a key issue for the future is sustainability of the natural resource base of South Africa. To attain this, the old traditional methods of research must be supplemented with the participatory method, where the local community becomes fully involved. The central theme of the participatory approach was to investigate the possibility of promoting local management of the natural resources. Workshops were conducted to involve the local community in the project. The community formed six discussion groups that met regularly to discuss environmental issues. The six groups that were formed were: Firewood or woodlot collectors, shepherds / livestock raisers, crop fanners / agriculturists, water collectors, building material / soil collectors and medicinal plant users. The results obtained from the meeting of the discussion groups were used to compare the scientific results obtained from Braun-Blanquet method. Perceptions about their environment, which came out of the results of the discussion groups showed that the local knowledge of the rural community of Mceula was sufficient to train them to manage their environment sustainably.
- Full Text:
- Authors: Nkansa-Dwamena, Yaw
- Date: 1998
- Subjects: Natural resources -- South Africa -- Management , Natural resources -- South Africa -- Eastern Cape -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4218 , http://hdl.handle.net/10962/d1003787 , Natural resources -- South Africa -- Management , Natural resources -- South Africa -- Eastern Cape -- Management
- Description: The Mceula Commonage Land in the Hewu district lies due northwest of Whittle sea and west of Queenstown in the Eastern Cape. This thesis has two main objectives. Firstly, to survey and analyse the condition of the natural resource. base in the Hewu district with particular reference to water, soil, vegetation and land use. Secondly, to investigate the relationship between scientific approaches to assessing land use degradation and to compare these to the results obtained using a participatory approach of the rural environment of the Hewu district of the Eastern Cape. Random quadrats (4m2) were sampled and corresponding line transects were done with increasing distances from the villages. The Braun-Blanquet method was used to find the cover and abundance of the various species of plants. Data obtained from point sampling along 100 metre line transects was used to assess the condition of the veld using Trollope's technique. Six communities were defined using TWINSP AN, and grazing capacities and veld condition scores of the respective sites were calculated. It was concluded that the six communities were distributed along a gradient of palatable to non palatable grass and grasslike species. Rangelands close to the villages had low veld condition scores and percentage plant cover as opposed to those farther away from the villages. The null hypothesis of no significant difference between the percentage plant cover and condition of the veld close to the villages and farther away from the villages was rejected. Whilst it is urgent to resolve political disputes around land through land distribution, a key issue for the future is sustainability of the natural resource base of South Africa. To attain this, the old traditional methods of research must be supplemented with the participatory method, where the local community becomes fully involved. The central theme of the participatory approach was to investigate the possibility of promoting local management of the natural resources. Workshops were conducted to involve the local community in the project. The community formed six discussion groups that met regularly to discuss environmental issues. The six groups that were formed were: Firewood or woodlot collectors, shepherds / livestock raisers, crop fanners / agriculturists, water collectors, building material / soil collectors and medicinal plant users. The results obtained from the meeting of the discussion groups were used to compare the scientific results obtained from Braun-Blanquet method. Perceptions about their environment, which came out of the results of the discussion groups showed that the local knowledge of the rural community of Mceula was sufficient to train them to manage their environment sustainably.
- Full Text:
New rules for security and survival: Southern Africa's adaptation to a changing world environment
- Authors: Naidoo, Sagaren Krishna
- Date: 1998
- Subjects: Internal security -- South Africa , National security -- South Africa , South Africa -- Politics and government -- 1994- , South Africa -- Economic conditions -- 1991-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2814 , http://hdl.handle.net/10962/d1003024 , Internal security -- South Africa , National security -- South Africa , South Africa -- Politics and government -- 1994- , South Africa -- Economic conditions -- 1991-
- Description: In the wake of the post-Cold War era, students of international relations were forced to review their theoretical frameworks to explain new rules for international peace and security. States are now confronted with new constraints for their security and survival as current trends in international politics depict a 'regionalisation' of peace and security. For southern Africa, likewise, the end of the Cold War and, moreover, apartheid, compels its member states to redefine their security strategies and mechanisms for survival. This thesis undertakes to examine southern Africa's adaptation to new rules of a changing world environment, to ensure a stable and secure region, into the next millennium. At the outset of this thesis lies a conceptual contextualisation of security within the major contemporary theoretical approaches of international relations. By examining the essential differences between the redefinitions and new conceptualisations of security, this thesis, firstly argues that the state in southern Africa must be retained as a primary referent of security. This argument is premised on the need to create stronger states for a 'regionalisation' of security in southern Africa. The second issue examined is the changing world environment and its impact on the state and development in Africa, as the new constraints to which the continent must adapt, for security and survival. Arguing that the new international economic order and 'globalisation' dictate the new rules, this chapter asserts that the 'weak' states in Africa need to be strengthened to have the necessary capacity to be the means for its people's security. Finally this thesis examines the new rules for southern Africa's adaptation to a changing world environment. The new rules for the African sub-continent involve the formation of a security regime and economic community with, the power-house, South Africa. Using the Southern African Development Community(SADC) as the umbrella body, the formation of the Organ for Politics, Defence and Security, and signing of trade protocols for a movement towards a free trade area, are evidence of southern Africa's attempts to adapt to new rules for its security. Such adaptation cannot, however, be accomplished with 'weak' states. Southern African states will have to, therefore, be strengthened to attain a more secure adaptation to the new international (economic) order.
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- Authors: Naidoo, Sagaren Krishna
- Date: 1998
- Subjects: Internal security -- South Africa , National security -- South Africa , South Africa -- Politics and government -- 1994- , South Africa -- Economic conditions -- 1991-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2814 , http://hdl.handle.net/10962/d1003024 , Internal security -- South Africa , National security -- South Africa , South Africa -- Politics and government -- 1994- , South Africa -- Economic conditions -- 1991-
- Description: In the wake of the post-Cold War era, students of international relations were forced to review their theoretical frameworks to explain new rules for international peace and security. States are now confronted with new constraints for their security and survival as current trends in international politics depict a 'regionalisation' of peace and security. For southern Africa, likewise, the end of the Cold War and, moreover, apartheid, compels its member states to redefine their security strategies and mechanisms for survival. This thesis undertakes to examine southern Africa's adaptation to new rules of a changing world environment, to ensure a stable and secure region, into the next millennium. At the outset of this thesis lies a conceptual contextualisation of security within the major contemporary theoretical approaches of international relations. By examining the essential differences between the redefinitions and new conceptualisations of security, this thesis, firstly argues that the state in southern Africa must be retained as a primary referent of security. This argument is premised on the need to create stronger states for a 'regionalisation' of security in southern Africa. The second issue examined is the changing world environment and its impact on the state and development in Africa, as the new constraints to which the continent must adapt, for security and survival. Arguing that the new international economic order and 'globalisation' dictate the new rules, this chapter asserts that the 'weak' states in Africa need to be strengthened to have the necessary capacity to be the means for its people's security. Finally this thesis examines the new rules for southern Africa's adaptation to a changing world environment. The new rules for the African sub-continent involve the formation of a security regime and economic community with, the power-house, South Africa. Using the Southern African Development Community(SADC) as the umbrella body, the formation of the Organ for Politics, Defence and Security, and signing of trade protocols for a movement towards a free trade area, are evidence of southern Africa's attempts to adapt to new rules for its security. Such adaptation cannot, however, be accomplished with 'weak' states. Southern African states will have to, therefore, be strengthened to attain a more secure adaptation to the new international (economic) order.
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Nifedipine-cyclodextrin binary systems : solid-state photostability and dissolution behaviour
- Worthington, Matthew Stanley
- Authors: Worthington, Matthew Stanley
- Date: 1998
- Subjects: Nifedipine Calcium -- Antagonists Cyclodextrins Cyclodextrins in pharmaceutical technology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3830 , http://hdl.handle.net/10962/d1007233
- Description: Nifedipine is a photolabile calcium channel antagonist which undergoes rapid photodegradation in solution and in solid-state with an accompanying loss of pharmacological potency and clinical efficacy. Nifedipine photostabilization which has received considerable attention has principally been achieved by physical obscuration and through the use of colourants or ultraviolet light absorbers incorporated into liquid preparations, translucent packaging materials, gelatin capsules and/or their fillings and tablet coatings or cores. This study was initiated by a South African pharmaceutical manufacturer in response to increasing evidence that cyclodextrin (CD) inclusion complexation may improve drug photostability. The brief was to evaluate the potential of selected cyclodextrins as photoprotecting agents for nifedipine in the solid-state. Areas of investigation included i) quantitative method development and validation for selective determination of nifedipine, ii) phase solubility studies to establish the solubilizing potential and complexing tendencies of selected cyclodextrins, iii) preparation of solid-state nifedipine - cyclodextrin binary systems using an industrially applicable method, iv) pre-formulation photostability studies to determine the effects of the cyclodextrins on solid-state nifedipine photostability and v) comparative in vitro dissolution assessments of nifedipine, the nifedipine - cyclodextrin binary systems and their respective physical mixtures. Phase solubility studies demonstrated that soluble nifedipine - cyclodextrin complexes were formed in aqueous solution, but the magnitude of the interactions were generally low as reflected by the calculated stability constants which decreased in the rank order, heptakis (2,6-dimethyI)-β-CD (DM-β-CD) > randomly methylated-β-CD (RM-β-CD) > β-CD ≈ 2-hydroxypropyl-β-CD (2HP-β- CD) > γ-CD ≥ 2-hydroxypropyl-γ-CD (2HP-γ-CD). An industrially applicable kneading method yielded binary systems with spectral and thermal characteristics similar to the respective physical mixtures, implying weak solid-state inclusion complexation. Preparation of an amorphous nifedipine - RM-β-CD product using a heating method is reported. A 1.7- and 1.9-fold improvement in solid-state nifedipine photostability was observed for I : 1 molar ratio β-CD and γ-CD kneaded products, respectively, when exposed to window-filtered daylight and could be attributed to changes in opacity of the crystalline kneaded products. The remaining cyclodextrins produced negligible nifedipine photostabilization. Nifedipine in vitro dissolution was improved considerably from γ-CD and RM-β-CD .kneaded products as a result of increased nifedipine wettability, solubility and reduced particle size. iii
- Full Text:
- Authors: Worthington, Matthew Stanley
- Date: 1998
- Subjects: Nifedipine Calcium -- Antagonists Cyclodextrins Cyclodextrins in pharmaceutical technology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3830 , http://hdl.handle.net/10962/d1007233
- Description: Nifedipine is a photolabile calcium channel antagonist which undergoes rapid photodegradation in solution and in solid-state with an accompanying loss of pharmacological potency and clinical efficacy. Nifedipine photostabilization which has received considerable attention has principally been achieved by physical obscuration and through the use of colourants or ultraviolet light absorbers incorporated into liquid preparations, translucent packaging materials, gelatin capsules and/or their fillings and tablet coatings or cores. This study was initiated by a South African pharmaceutical manufacturer in response to increasing evidence that cyclodextrin (CD) inclusion complexation may improve drug photostability. The brief was to evaluate the potential of selected cyclodextrins as photoprotecting agents for nifedipine in the solid-state. Areas of investigation included i) quantitative method development and validation for selective determination of nifedipine, ii) phase solubility studies to establish the solubilizing potential and complexing tendencies of selected cyclodextrins, iii) preparation of solid-state nifedipine - cyclodextrin binary systems using an industrially applicable method, iv) pre-formulation photostability studies to determine the effects of the cyclodextrins on solid-state nifedipine photostability and v) comparative in vitro dissolution assessments of nifedipine, the nifedipine - cyclodextrin binary systems and their respective physical mixtures. Phase solubility studies demonstrated that soluble nifedipine - cyclodextrin complexes were formed in aqueous solution, but the magnitude of the interactions were generally low as reflected by the calculated stability constants which decreased in the rank order, heptakis (2,6-dimethyI)-β-CD (DM-β-CD) > randomly methylated-β-CD (RM-β-CD) > β-CD ≈ 2-hydroxypropyl-β-CD (2HP-β- CD) > γ-CD ≥ 2-hydroxypropyl-γ-CD (2HP-γ-CD). An industrially applicable kneading method yielded binary systems with spectral and thermal characteristics similar to the respective physical mixtures, implying weak solid-state inclusion complexation. Preparation of an amorphous nifedipine - RM-β-CD product using a heating method is reported. A 1.7- and 1.9-fold improvement in solid-state nifedipine photostability was observed for I : 1 molar ratio β-CD and γ-CD kneaded products, respectively, when exposed to window-filtered daylight and could be attributed to changes in opacity of the crystalline kneaded products. The remaining cyclodextrins produced negligible nifedipine photostabilization. Nifedipine in vitro dissolution was improved considerably from γ-CD and RM-β-CD .kneaded products as a result of increased nifedipine wettability, solubility and reduced particle size. iii
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Preliminary investigation of the molecular pathogenicity determinants of Xanthomonas campestris pv. zeae
- Authors: Downing, T G
- Date: 1998
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4066 , http://hdl.handle.net/10962/d1004922
- Description: Xanthomonas campestris pv. zeae was shown to posses a vast range of potential plant cell wall degrading enzymes including at least one protease, a carboxymethylcellulase, pectin lyase, polygalacturonase and a B-endoglucanase. Replicon stability and transfer system efficiencies were determined for a range of oriC, and oriT -tra combinations, and suitable vectors were constructed and identified for insertional inactivation by homologous recombination. Ideal suicide replicons were found to be pACYC184 and p15A, while P, Wand Q group replicons were supported by X campestris pv. zeae. Group P and group N transfer systems were shown to be highly efficient in intra-genus matings between Escherichia coli and X campestris pv. zeae, with the exception of P-tra systems in trans for the delivery of Tn5. Various cloning vectors were tested for stability and mobility. Tn5 was shown to transpose at high frequencies into the genome of the bacterial plant pathogen, and insertion was relatively random. Suitable screening assays were established to allow rapid isolation of mutants with potential virulence or pathogenic deviations, after mutagenesis. Two non-pathogenic mutants were identified, one of which was a putative hrp·, while the other was a leaky virulence. A single mutant showing 40% reduced protease activity was also shown to exhibit reduced virulence indicating a minor role for the protease in pathogenicity. The majority of virulence mutants showed altered growth in different levels of nutritional availability and complexity. Nutritional viability (the ability to acquire and use nutrients at a sufficient rate to grow fast enough to overcome host defences) was shown to be essential for virulence and possibly pathogenicity. Wild-type in-planta behaviour was analysed and growth and spread patterns typical for pathogenic response identified. Chief amongst these was the requirement for a threshold level of cells per leaf area or length, before symptoms could develop. Occlusion of vascular bundles was shown not to be the primary factor in the pathogenicity of X campestris pv. zeae. Threshold levels for lesion development indicate the absence of a diffusable lesion forming element, and possibly the requirement of cell density for induction of certain functions. , KMBT_363
- Full Text:
- Authors: Downing, T G
- Date: 1998
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4066 , http://hdl.handle.net/10962/d1004922
- Description: Xanthomonas campestris pv. zeae was shown to posses a vast range of potential plant cell wall degrading enzymes including at least one protease, a carboxymethylcellulase, pectin lyase, polygalacturonase and a B-endoglucanase. Replicon stability and transfer system efficiencies were determined for a range of oriC, and oriT -tra combinations, and suitable vectors were constructed and identified for insertional inactivation by homologous recombination. Ideal suicide replicons were found to be pACYC184 and p15A, while P, Wand Q group replicons were supported by X campestris pv. zeae. Group P and group N transfer systems were shown to be highly efficient in intra-genus matings between Escherichia coli and X campestris pv. zeae, with the exception of P-tra systems in trans for the delivery of Tn5. Various cloning vectors were tested for stability and mobility. Tn5 was shown to transpose at high frequencies into the genome of the bacterial plant pathogen, and insertion was relatively random. Suitable screening assays were established to allow rapid isolation of mutants with potential virulence or pathogenic deviations, after mutagenesis. Two non-pathogenic mutants were identified, one of which was a putative hrp·, while the other was a leaky virulence. A single mutant showing 40% reduced protease activity was also shown to exhibit reduced virulence indicating a minor role for the protease in pathogenicity. The majority of virulence mutants showed altered growth in different levels of nutritional availability and complexity. Nutritional viability (the ability to acquire and use nutrients at a sufficient rate to grow fast enough to overcome host defences) was shown to be essential for virulence and possibly pathogenicity. Wild-type in-planta behaviour was analysed and growth and spread patterns typical for pathogenic response identified. Chief amongst these was the requirement for a threshold level of cells per leaf area or length, before symptoms could develop. Occlusion of vascular bundles was shown not to be the primary factor in the pathogenicity of X campestris pv. zeae. Threshold levels for lesion development indicate the absence of a diffusable lesion forming element, and possibly the requirement of cell density for induction of certain functions. , KMBT_363
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