An exploration of the social worker's role in promoting sustainability of poverty alleviating projects
- Ndude, Peace-Maker Mqokeleli
- Authors: Ndude, Peace-Maker Mqokeleli
- Date: 2002
- Subjects: Poverty -- South Africa , Poor -- Services for -- South Africa , Social service -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:6058 , http://hdl.handle.net/10962/d1006664 , Poverty -- South Africa , Poor -- Services for -- South Africa , Social service -- South Africa
- Description: In this research study the researcher attempted to gain an insight on what constitutes sustainability of poverty alleviating projects. Further, the researcher attempted to explore and gain understanding of the role of social worker in promoting sustainability of poverty alleviating projects. Since the literature on sustainability is limited, it is hoped that this study will provide valuable information for further research on the topic. In the limited literature study undertaken however, it was evident that despite the generic service that they provide, social workers have a role to play in community development. It was found that social workers can no longer afford to restrict their service provision to the traditional methods of social work. The egalitarian nature of their profession demands that they occupy the centre stage in poverty alleviation as they are strategically placed between the poor and the decision-makers in government. Eighteen respondents composed of six social workers, six committee members and six community members from six poverty alleviating projects were interviewed. One project from each of the six districts of Tsomo, Nqamakwe, Butterworth, Centane, Idutywa and Willowvale were used in the research study. The fmdings suggested that social workers, committee members and community members have differing opinions on what promotes or impedes sustainability of poverty alleviating projects, All respondents however agreed that participation as well as empowerment through training were basic requirements towards sustainability of poverty alleviating projects. Again the findings agreed with the literature that social workers have an important role to play in promoting sustainability of poverty alleviating projects.
- Full Text:
- Date Issued: 2002
- Authors: Ndude, Peace-Maker Mqokeleli
- Date: 2002
- Subjects: Poverty -- South Africa , Poor -- Services for -- South Africa , Social service -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:6058 , http://hdl.handle.net/10962/d1006664 , Poverty -- South Africa , Poor -- Services for -- South Africa , Social service -- South Africa
- Description: In this research study the researcher attempted to gain an insight on what constitutes sustainability of poverty alleviating projects. Further, the researcher attempted to explore and gain understanding of the role of social worker in promoting sustainability of poverty alleviating projects. Since the literature on sustainability is limited, it is hoped that this study will provide valuable information for further research on the topic. In the limited literature study undertaken however, it was evident that despite the generic service that they provide, social workers have a role to play in community development. It was found that social workers can no longer afford to restrict their service provision to the traditional methods of social work. The egalitarian nature of their profession demands that they occupy the centre stage in poverty alleviation as they are strategically placed between the poor and the decision-makers in government. Eighteen respondents composed of six social workers, six committee members and six community members from six poverty alleviating projects were interviewed. One project from each of the six districts of Tsomo, Nqamakwe, Butterworth, Centane, Idutywa and Willowvale were used in the research study. The fmdings suggested that social workers, committee members and community members have differing opinions on what promotes or impedes sustainability of poverty alleviating projects, All respondents however agreed that participation as well as empowerment through training were basic requirements towards sustainability of poverty alleviating projects. Again the findings agreed with the literature that social workers have an important role to play in promoting sustainability of poverty alleviating projects.
- Full Text:
- Date Issued: 2002
An investigation into the possible neuroprotective properties of phenytoin
- Authors: Naga, Nishal
- Date: 2002
- Subjects: Phenytoin -- Therapeutic use , Phenytoin -- Physiological effect , Nervous system -- Degeneration -- Prevention
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3780 , http://hdl.handle.net/10962/d1003258 , Phenytoin -- Therapeutic use , Phenytoin -- Physiological effect , Nervous system -- Degeneration -- Prevention
- Description: Cerebral ischaemia, traumatic injury to the brain, inflammatory neurological disorders and HIV infections are amongst the most prevalent causes of neurodegeneration. Neuroprotective strategies are usually to limit the progressive secondary injury that generally occurs, thus limiting overall tissue damage. Neuroprotective strategies are usually to limit the progressive secondary injury that generally occurs, thus limiting overall tissue damage. Sodium channel blockers have been often used for this matter as they prevent the cascade of events culminating in free radical generation and eventually neuronal apoptosis. Newer compounds, such as antiperoxidants and free radical scavengers, show encouraging experimental results, but their clinical use is still very limited. Phenytoin being a popular drug in the treatment of epilepsy has also been used as a neuroprotectant during certain neurological emergencies and in pharmacological prophylaxis of post-traumatic epilepsy. Furthermore this agent functions by prolonging inactivation of voltage gated sodium channels. In these sets of experiment the neuroprotective properties of phenytoin were examined. The histological study revealed that phenytoin confers protection to the CA1 and CA3 regions of the hippocampus under the insult of QUIN. Cells maintain their characteristic shape and minimal tissue necrosis occurs in the presence of this agent. The in vitro effect of this antiepileptic drug on free radicals generation shows that phenytoin does not reduce or prevent the formation of these reactive species. Lipid peroxidation was induced using QUIN and iron (II), two known neurotoxins. The study reveals that only lipid peroxidation induced using iron (II) is reduced by phenytoin. These experiments were carried out in whole rat brain homogenate. These studies show that phenytoin possesses poor free radical scavenging properties. However, the dose-related reduction of iron-induced lipid peroxidation allows for speculation that phenytoin interacts with iron in order to reduce neuronal damage. Metal binding studies were performed using UV, IR and electrochemical analysis to examine the interaction of phenytoin with iron (II) and iron (III). Phenytoin, when added to iron (II) in solution, first oxidises the latter to iron (III) and maintains it in that form. A shift in the peak was observed in the UV spectrum when iron was added to phenytoin. Moreover, electrochemical studies indicate that the interaction between the metal and the ligand is very weak. The IR analysis it shows that phenytoin may be coordinating with iron through the Nitrogen atom on the phenytoin molecule. These studies show that phenytoin maintains iron in its oxidised form, which is a good property to possess as a neuroprotectants. Pineal organ culture showed that phenytoin does not increase melatonin production but slightly and non-significantly reduces the levels of this pineal hormone. However there is a significant rise in precursor NAS levels. As melatonin is known to possess antioxidant and free radical scavenging properties, this could mean that this drug can cause the CNS to become more susceptible to attacks by reactive oxygen species.
- Full Text:
- Date Issued: 2002
- Authors: Naga, Nishal
- Date: 2002
- Subjects: Phenytoin -- Therapeutic use , Phenytoin -- Physiological effect , Nervous system -- Degeneration -- Prevention
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3780 , http://hdl.handle.net/10962/d1003258 , Phenytoin -- Therapeutic use , Phenytoin -- Physiological effect , Nervous system -- Degeneration -- Prevention
- Description: Cerebral ischaemia, traumatic injury to the brain, inflammatory neurological disorders and HIV infections are amongst the most prevalent causes of neurodegeneration. Neuroprotective strategies are usually to limit the progressive secondary injury that generally occurs, thus limiting overall tissue damage. Neuroprotective strategies are usually to limit the progressive secondary injury that generally occurs, thus limiting overall tissue damage. Sodium channel blockers have been often used for this matter as they prevent the cascade of events culminating in free radical generation and eventually neuronal apoptosis. Newer compounds, such as antiperoxidants and free radical scavengers, show encouraging experimental results, but their clinical use is still very limited. Phenytoin being a popular drug in the treatment of epilepsy has also been used as a neuroprotectant during certain neurological emergencies and in pharmacological prophylaxis of post-traumatic epilepsy. Furthermore this agent functions by prolonging inactivation of voltage gated sodium channels. In these sets of experiment the neuroprotective properties of phenytoin were examined. The histological study revealed that phenytoin confers protection to the CA1 and CA3 regions of the hippocampus under the insult of QUIN. Cells maintain their characteristic shape and minimal tissue necrosis occurs in the presence of this agent. The in vitro effect of this antiepileptic drug on free radicals generation shows that phenytoin does not reduce or prevent the formation of these reactive species. Lipid peroxidation was induced using QUIN and iron (II), two known neurotoxins. The study reveals that only lipid peroxidation induced using iron (II) is reduced by phenytoin. These experiments were carried out in whole rat brain homogenate. These studies show that phenytoin possesses poor free radical scavenging properties. However, the dose-related reduction of iron-induced lipid peroxidation allows for speculation that phenytoin interacts with iron in order to reduce neuronal damage. Metal binding studies were performed using UV, IR and electrochemical analysis to examine the interaction of phenytoin with iron (II) and iron (III). Phenytoin, when added to iron (II) in solution, first oxidises the latter to iron (III) and maintains it in that form. A shift in the peak was observed in the UV spectrum when iron was added to phenytoin. Moreover, electrochemical studies indicate that the interaction between the metal and the ligand is very weak. The IR analysis it shows that phenytoin may be coordinating with iron through the Nitrogen atom on the phenytoin molecule. These studies show that phenytoin maintains iron in its oxidised form, which is a good property to possess as a neuroprotectants. Pineal organ culture showed that phenytoin does not increase melatonin production but slightly and non-significantly reduces the levels of this pineal hormone. However there is a significant rise in precursor NAS levels. As melatonin is known to possess antioxidant and free radical scavenging properties, this could mean that this drug can cause the CNS to become more susceptible to attacks by reactive oxygen species.
- Full Text:
- Date Issued: 2002
An investigation into the possible neuroprotective role of antidepressant drugs
- Authors: Steiner, Claire
- Date: 2002
- Subjects: Antidepressants -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3792 , http://hdl.handle.net/10962/d1003270 , Antidepressants -- Research
- Description: Antidepressants are widely used in the treatment of depressive illnesses associated with neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease and Huntington’s disease. Neuroprotection in such disorders is of vital importance in order to delay the progression of the primary disorder. The pathology of neurodegeneration is not fully understood. It is however widely accepted that oxidative stress and excitotoxicity play a major role. Brain tissue is rich in phospholipids, which are especially prone to oxidation due to the high level of oxygen utilization in the brain. In addition, the brain lacks defence mechanisms to protect it against the wrath of free radicals. Presently, there is a wide variety of antidepressant drugs available. These range from the original tricyclic antidepressants to the newer selective serotonin reuptake inhibitors. It is not known whether antidepressant drugs, old or new, offer neuroprotection or how the existing state and/or the progression of neurodegeneration, is influenced by these agents. The present study was undertaken to determine how nortriptyline, trimipramine and fluoxetine affect neurodegeneration. Initial in vitro and in vivo studies show that all three of the antidepressants (0-1mM) studied provide neuroprotection from quinolinic acid induced lipid peroxidation. A histological investigation supported these findings by showing that a marginal degree of neuroprotection is apparent when treating animals with antidepressants (10mg/kg) before and following quinolinic acid intrastriatal injection. Further studies were undertaken in an attempt to determine the mode of neuroprotective action of the agents studied. An in vitro study of superoxide anion induced lipid peroxidation indicates that these agents do not act as antioxidants. The influence of the antidepressants on tryptophan 2,3-dioxygenase activity was assessed, based on the understanding that inhibition of this enzyme results in increased levels of the known antioxidant indoleamine, melatonin. Nortriptyline hydrochloride is seen to inhibit tryptophan 2,3-dioxygenase activity and as such it is possible that this antidepressant can indirectly provide neuroprotection by increasing available melatonin. Electrochemical and UV/visible studies show that trimipramine maleate interacts with free iron (II) and iron (III) ions. Free metal ions can catalyse the formation of damaging free radicals. Through interaction with trimipramine maleate, these ions will be unavailable to the system and thus cannot contribute to oxidative stress. The findings of this study indicate that antidepressants may be able to provide neuroprotection to neuronal cells. The mode of such neuroprotective actions need to be further examined so that patients suffering from depression coexisting with neurodegenerative diseases can be safely and effectively treated.
- Full Text:
- Date Issued: 2002
- Authors: Steiner, Claire
- Date: 2002
- Subjects: Antidepressants -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3792 , http://hdl.handle.net/10962/d1003270 , Antidepressants -- Research
- Description: Antidepressants are widely used in the treatment of depressive illnesses associated with neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease and Huntington’s disease. Neuroprotection in such disorders is of vital importance in order to delay the progression of the primary disorder. The pathology of neurodegeneration is not fully understood. It is however widely accepted that oxidative stress and excitotoxicity play a major role. Brain tissue is rich in phospholipids, which are especially prone to oxidation due to the high level of oxygen utilization in the brain. In addition, the brain lacks defence mechanisms to protect it against the wrath of free radicals. Presently, there is a wide variety of antidepressant drugs available. These range from the original tricyclic antidepressants to the newer selective serotonin reuptake inhibitors. It is not known whether antidepressant drugs, old or new, offer neuroprotection or how the existing state and/or the progression of neurodegeneration, is influenced by these agents. The present study was undertaken to determine how nortriptyline, trimipramine and fluoxetine affect neurodegeneration. Initial in vitro and in vivo studies show that all three of the antidepressants (0-1mM) studied provide neuroprotection from quinolinic acid induced lipid peroxidation. A histological investigation supported these findings by showing that a marginal degree of neuroprotection is apparent when treating animals with antidepressants (10mg/kg) before and following quinolinic acid intrastriatal injection. Further studies were undertaken in an attempt to determine the mode of neuroprotective action of the agents studied. An in vitro study of superoxide anion induced lipid peroxidation indicates that these agents do not act as antioxidants. The influence of the antidepressants on tryptophan 2,3-dioxygenase activity was assessed, based on the understanding that inhibition of this enzyme results in increased levels of the known antioxidant indoleamine, melatonin. Nortriptyline hydrochloride is seen to inhibit tryptophan 2,3-dioxygenase activity and as such it is possible that this antidepressant can indirectly provide neuroprotection by increasing available melatonin. Electrochemical and UV/visible studies show that trimipramine maleate interacts with free iron (II) and iron (III) ions. Free metal ions can catalyse the formation of damaging free radicals. Through interaction with trimipramine maleate, these ions will be unavailable to the system and thus cannot contribute to oxidative stress. The findings of this study indicate that antidepressants may be able to provide neuroprotection to neuronal cells. The mode of such neuroprotective actions need to be further examined so that patients suffering from depression coexisting with neurodegenerative diseases can be safely and effectively treated.
- Full Text:
- Date Issued: 2002
An investigation into the viability of deploying thin client technology to support effective learning in a disadvantaged, rural high school setting
- Authors: Ndwe, Tembalethu Jama
- Date: 2002
- Subjects: Network computers , Education -- Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4627 , http://hdl.handle.net/10962/d1006500 , Network computers , Education -- Data processing
- Description: Computer Based Training offers many attractive learning opportunities for high school pupils. Its deployment in economically depressed and educationally marginalized rural schools is extremely uncommon due to the high technology skills and costs involved in its deployment and ongoing maintenance. This thesis puts forward thin client technology as a potential solution to the needs of education environments of this kind. A functional business case is developed and evaluated in this thesis, based upon a requirements analysis of media delivery in learning, and upon formal cost/performance models and a deployment field trial. Because of the economic constraints of the envisaged deployment area in rural education, an industrial field trial is used, and the aspects of this trial that can be carried over to the rural school situation have been used to assess performance and cost indicators. Our study finds that thin client technology could be deployed and maintained more cost effectively than conventional fat client solutions in rural schools, that it is capable of supporting the learning elements needed in this deployment area, and that it is able to deliver the predominantly text based applications currently being used in schools. However, we find that technological improvements are needed before future multimediaintensive applications can be adequately supported.
- Full Text:
- Date Issued: 2002
- Authors: Ndwe, Tembalethu Jama
- Date: 2002
- Subjects: Network computers , Education -- Data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4627 , http://hdl.handle.net/10962/d1006500 , Network computers , Education -- Data processing
- Description: Computer Based Training offers many attractive learning opportunities for high school pupils. Its deployment in economically depressed and educationally marginalized rural schools is extremely uncommon due to the high technology skills and costs involved in its deployment and ongoing maintenance. This thesis puts forward thin client technology as a potential solution to the needs of education environments of this kind. A functional business case is developed and evaluated in this thesis, based upon a requirements analysis of media delivery in learning, and upon formal cost/performance models and a deployment field trial. Because of the economic constraints of the envisaged deployment area in rural education, an industrial field trial is used, and the aspects of this trial that can be carried over to the rural school situation have been used to assess performance and cost indicators. Our study finds that thin client technology could be deployed and maintained more cost effectively than conventional fat client solutions in rural schools, that it is capable of supporting the learning elements needed in this deployment area, and that it is able to deliver the predominantly text based applications currently being used in schools. However, we find that technological improvements are needed before future multimediaintensive applications can be adequately supported.
- Full Text:
- Date Issued: 2002
An investigation of the management and leadership experiences of female school principals in the Ondangwa education regions
- Authors: Udjombala, Maria
- Date: 2002
- Subjects: Women school principals -- Namibia -- Ondangwa Educational leadership -- Namibia -- Ondangwa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1653 , http://hdl.handle.net/10962/d1003536
- Description: This study explores practical school leadership and management, as enacted by women. The study, conducted in an interpretive paradigm, attempts to gain an understanding of women’s subjective experiences of school leadership and management. Two women principals from Ondangwa West Educational Region were interviewed. The two were selected through consultations with one of the senior inspectors in the region. Both had been principals for more than ten years and were seen by those who are concerned with their school to be successful. The study found that these women prefer a participative style of leadership and management, characterised by consultations with others, teamwork, collaborative decision-making and the use of power to empower others. They also strive for good human relationships because they believe that it fosters mutual respect, trust, openness and a good working atmosphere. All these human centred approaches are directed towards creating a school atmosphere that is conducive to teaching and learning and therefore result in effective schooling and quality educational outcomes. They do not experience gender discrimination in their work places. They have the full support of their supervisors. Though both are married with children, these dual roles do not prevent them from being successful in their professional work. In fact they have reached a stage where they feel confident as leaders and feel that they are acting as role models for fellow women principals and those aspiring to this position. The study concludes that the styles of leadership and management displayed by women are similar to those that are universally accepted as characteristics needed for effective school management and leadership. Though these leadership styles are traditionally associated with women, these characteristics are not gender specific. Therefore it will be in the best interest of schools, if school principals, both men and women, could borrow from these qualities in order to change schools from authoritarian to more democratic institutions.
- Full Text:
- Date Issued: 2002
- Authors: Udjombala, Maria
- Date: 2002
- Subjects: Women school principals -- Namibia -- Ondangwa Educational leadership -- Namibia -- Ondangwa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1653 , http://hdl.handle.net/10962/d1003536
- Description: This study explores practical school leadership and management, as enacted by women. The study, conducted in an interpretive paradigm, attempts to gain an understanding of women’s subjective experiences of school leadership and management. Two women principals from Ondangwa West Educational Region were interviewed. The two were selected through consultations with one of the senior inspectors in the region. Both had been principals for more than ten years and were seen by those who are concerned with their school to be successful. The study found that these women prefer a participative style of leadership and management, characterised by consultations with others, teamwork, collaborative decision-making and the use of power to empower others. They also strive for good human relationships because they believe that it fosters mutual respect, trust, openness and a good working atmosphere. All these human centred approaches are directed towards creating a school atmosphere that is conducive to teaching and learning and therefore result in effective schooling and quality educational outcomes. They do not experience gender discrimination in their work places. They have the full support of their supervisors. Though both are married with children, these dual roles do not prevent them from being successful in their professional work. In fact they have reached a stage where they feel confident as leaders and feel that they are acting as role models for fellow women principals and those aspiring to this position. The study concludes that the styles of leadership and management displayed by women are similar to those that are universally accepted as characteristics needed for effective school management and leadership. Though these leadership styles are traditionally associated with women, these characteristics are not gender specific. Therefore it will be in the best interest of schools, if school principals, both men and women, could borrow from these qualities in order to change schools from authoritarian to more democratic institutions.
- Full Text:
- Date Issued: 2002
An investigation of the neuroprotective effects of estrogen in a model of quinolinic acid-induced neurodegeneration
- Authors: Heron, Paula Michelle
- Date: 2002
- Subjects: Estrogen , Quinolinic acid , Nervous system -- Degeneration
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3759 , http://hdl.handle.net/10962/d1003237 , Estrogen , Quinolinic acid , Nervous system -- Degeneration
- Description: The hippocampus, located in the medial temporal lobe, is an important region of the brain responsible for the formation of memory. Thus, any agent that induces stress in this area has detrimental effects and could lead to various types of dementia. Such agents include the neurotoxin, Quinolinic acid. Quinolinic acid (QUIN) is a neurotoxic metabolite of the tryptophan-kynurenine pathway and is an endogenous glutamate agonist that selectively injures and kills vulnerable neurons via the activation of the NMDA class of excitatory amino acid receptors. Estrogen is a female hormone that is responsible for reproduction. However, in the last decade estrogen has been shown to exhibit a wide range of actions on the brain, including neuroprotection. Estrogen has been shown to exhibit intrinsic antioxidant activity and protects cultured neurons against oxidative cell death. This is achieved by estrogen’s ability to scavenge free radicals, which is dependent on the presence of the hydroxyl group at the C3 position on the A ring of the steroid molecule. Numerous studies have shown that estrogen protects neurons against various toxic substances and may play a role in delaying the onset of neurodegenerative diseases, such as Alzheimer’s disease. Neuronal damage due to oxidative stress has been implicated in several neurodegenerative disorders. The detection and measurement of lipid peroxidation is the evidence most frequently cited to support the involvement of free radical reactions in toxicology and in human disease. The study aims to elucidate and further characterise the mechanism behind estrogen’s neuroprotection, using QUIN as a model of neurotoxicity. Initial studies confirm estrogen’s ability to scavenge potent free radicals. In addition, the results show that estrogen forms an interaction with iron (II) and also acts at the NMDA receptor as an agonist. Both mechanisms reduce the ability of QUIN to cause damage to neurons, since QUIN-induced toxicity is dependent on the activation of the NMDA receptor and the formation of a complex with iron (II) to induce lipid peroxidation. Heat shock proteins, especially Hsp 70 play a role in cytoprotection by capturing denatured proteins and facilitating the refolding of these proteins once the stress has been relieved. Estrogen has been shown to increase the level of expression of Hsp70, both inducible and cognate forms of the protein. This suggests that estrogen helps to protect against cellular protein damage induced by any form of stress the cell may encounter. The discovery of neuroprotective agents, such as estrogen, is becoming important as accumulating evidence indicates a protective role in vivo. Thus further research may favour the use of these agents in the treatment of several neurodegenerative disorders. Considering how devastating diseases, such as Alzheimer’s disease, are to a patient and the patient’s families, the discovery of new protective agents are a matter of urgency.
- Full Text:
- Date Issued: 2002
- Authors: Heron, Paula Michelle
- Date: 2002
- Subjects: Estrogen , Quinolinic acid , Nervous system -- Degeneration
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3759 , http://hdl.handle.net/10962/d1003237 , Estrogen , Quinolinic acid , Nervous system -- Degeneration
- Description: The hippocampus, located in the medial temporal lobe, is an important region of the brain responsible for the formation of memory. Thus, any agent that induces stress in this area has detrimental effects and could lead to various types of dementia. Such agents include the neurotoxin, Quinolinic acid. Quinolinic acid (QUIN) is a neurotoxic metabolite of the tryptophan-kynurenine pathway and is an endogenous glutamate agonist that selectively injures and kills vulnerable neurons via the activation of the NMDA class of excitatory amino acid receptors. Estrogen is a female hormone that is responsible for reproduction. However, in the last decade estrogen has been shown to exhibit a wide range of actions on the brain, including neuroprotection. Estrogen has been shown to exhibit intrinsic antioxidant activity and protects cultured neurons against oxidative cell death. This is achieved by estrogen’s ability to scavenge free radicals, which is dependent on the presence of the hydroxyl group at the C3 position on the A ring of the steroid molecule. Numerous studies have shown that estrogen protects neurons against various toxic substances and may play a role in delaying the onset of neurodegenerative diseases, such as Alzheimer’s disease. Neuronal damage due to oxidative stress has been implicated in several neurodegenerative disorders. The detection and measurement of lipid peroxidation is the evidence most frequently cited to support the involvement of free radical reactions in toxicology and in human disease. The study aims to elucidate and further characterise the mechanism behind estrogen’s neuroprotection, using QUIN as a model of neurotoxicity. Initial studies confirm estrogen’s ability to scavenge potent free radicals. In addition, the results show that estrogen forms an interaction with iron (II) and also acts at the NMDA receptor as an agonist. Both mechanisms reduce the ability of QUIN to cause damage to neurons, since QUIN-induced toxicity is dependent on the activation of the NMDA receptor and the formation of a complex with iron (II) to induce lipid peroxidation. Heat shock proteins, especially Hsp 70 play a role in cytoprotection by capturing denatured proteins and facilitating the refolding of these proteins once the stress has been relieved. Estrogen has been shown to increase the level of expression of Hsp70, both inducible and cognate forms of the protein. This suggests that estrogen helps to protect against cellular protein damage induced by any form of stress the cell may encounter. The discovery of neuroprotective agents, such as estrogen, is becoming important as accumulating evidence indicates a protective role in vivo. Thus further research may favour the use of these agents in the treatment of several neurodegenerative disorders. Considering how devastating diseases, such as Alzheimer’s disease, are to a patient and the patient’s families, the discovery of new protective agents are a matter of urgency.
- Full Text:
- Date Issued: 2002
Aspects pertinent to the provision of sustainable water supply projects in the Eastern Cape Province: a case study of Nomzamo Water Supply Project
- Authors: Mpendu, Daluhlanga Ayford
- Date: 2002
- Subjects: Water-supply -- South Africa -- Eastern Cape Nomzamo Water Supply Project Water-supply -- South Africa -- Social aspects
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:5952 , http://hdl.handle.net/10962/d1007450
- Description: This study explores views behind the failure of water supply projects to achieve sustainability, primarily from the 'users' perspective, and at a secondary level from the perspective of the government/funders. One completed water supply project was selected as a case study for the research project. The overriding principle behind the water infrastructure delivery programme is that the service must be provided in a sustainable manner, and that the community must actively participate and be involved in all the phases of the project. The provision of water is not simply as it might look. In reality it is a complex process, which involves a number of organisations with different, yet important roles and responsibilities. Ongoing collaboration is important among these organisations if the service is to be provided efficiently and in a sustainable manner. In particular, local government has a Constitutional obligation to provide services to all consumers in an efficient, affordable, economical and sustainable manner. The National and Provincial governments, however, have a number of responsibilities in the field of water services. Semi-structured interview method was used to collect data from respondents. Two sets of interview schedules were developed, one for the community/water project committee members, and the other for the government officials. The data collected was analysed both qualitatively and quantitatively. This analysis enabled the researcher to draw findings, make conclusions and propose recommendations. The findings and conclusions of the study point to lack of clarity on roles and responsibilities; gender and cultural constraints; and, poor training and capacity and building of the community as being some of the reasons for the failure of the project. The recommendations proposed entail, inter alia, massive community mobilisation and awareness creation programmes; improvement in levels of the service; adoption of a gender-sensitive approach to project development; and, implementation of a training and capacity building process in the community in order to 'revitalise' the project. The study has merely focussed on one water project and sets the scene for further exploration of the subject. It certainly highlights some critical issues around sustainability of water projects, and hopefully will contribute towards the ongoing debate in this area.
- Full Text:
- Date Issued: 2002
- Authors: Mpendu, Daluhlanga Ayford
- Date: 2002
- Subjects: Water-supply -- South Africa -- Eastern Cape Nomzamo Water Supply Project Water-supply -- South Africa -- Social aspects
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:5952 , http://hdl.handle.net/10962/d1007450
- Description: This study explores views behind the failure of water supply projects to achieve sustainability, primarily from the 'users' perspective, and at a secondary level from the perspective of the government/funders. One completed water supply project was selected as a case study for the research project. The overriding principle behind the water infrastructure delivery programme is that the service must be provided in a sustainable manner, and that the community must actively participate and be involved in all the phases of the project. The provision of water is not simply as it might look. In reality it is a complex process, which involves a number of organisations with different, yet important roles and responsibilities. Ongoing collaboration is important among these organisations if the service is to be provided efficiently and in a sustainable manner. In particular, local government has a Constitutional obligation to provide services to all consumers in an efficient, affordable, economical and sustainable manner. The National and Provincial governments, however, have a number of responsibilities in the field of water services. Semi-structured interview method was used to collect data from respondents. Two sets of interview schedules were developed, one for the community/water project committee members, and the other for the government officials. The data collected was analysed both qualitatively and quantitatively. This analysis enabled the researcher to draw findings, make conclusions and propose recommendations. The findings and conclusions of the study point to lack of clarity on roles and responsibilities; gender and cultural constraints; and, poor training and capacity and building of the community as being some of the reasons for the failure of the project. The recommendations proposed entail, inter alia, massive community mobilisation and awareness creation programmes; improvement in levels of the service; adoption of a gender-sensitive approach to project development; and, implementation of a training and capacity building process in the community in order to 'revitalise' the project. The study has merely focussed on one water project and sets the scene for further exploration of the subject. It certainly highlights some critical issues around sustainability of water projects, and hopefully will contribute towards the ongoing debate in this area.
- Full Text:
- Date Issued: 2002
Assessing the need for specific services for HIV/AIDS affected people using participatory needs assessment processes
- Authors: Moresby-White, Ann
- Date: 2002
- Subjects: AIDS (Disease) -- Patients -- Services for , HIV-positive persons -- Services for , AIDS (Disease) -- Research , AIDS (Disease) -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:713 , http://hdl.handle.net/10962/d1007692 , AIDS (Disease) -- Patients -- Services for , HIV-positive persons -- Services for , AIDS (Disease) -- Research , AIDS (Disease) -- South Africa
- Description: The purpose of the study undertaken is to develop knowledge to assist service providers in their planning and implementation of community -based programmes and projects. The thesis explores the most appropriate way of conducting a needs assessment, relating to HIV/AIDS services in a particular community; thereafter the needs assessment was carried out. This qualitative research study is conducted using participatory methods and techniques. The research reviews literature pertaining to HIV/AIDS, specifically in Africa, South Africa and the Eastern Cape and incorporates a discussion on the concept of community, community development and poverty. The design of the needs assessment tool, implementation and analysis is conducted through focus group discussions and individual semi-structured interviews. The theory on participatory approaches and community development are central to this study. The study found that HIV / AIDS as an issue is not perceived by the community under study to be an immediate need in light of basic needs being identified as priority. The use of participatory methods in this study highlighted the diversity within communities. Service providers who wish to initiate community - based projects need to take note of diversity and personal interests of individuals or groups who become involved in community- based projects. The study further highlighted the need for service providers to provide training, to their staff in participatory approaches and techniques, before embarking on community development projects. The study concludes that services relating to the HIV/AIDS epidemic cannot be carried out in isolation, but that an integrated approach is needed in the planning and implementation of services and programmes to address those affected by HIV/AIDS.
- Full Text:
- Date Issued: 2002
- Authors: Moresby-White, Ann
- Date: 2002
- Subjects: AIDS (Disease) -- Patients -- Services for , HIV-positive persons -- Services for , AIDS (Disease) -- Research , AIDS (Disease) -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:713 , http://hdl.handle.net/10962/d1007692 , AIDS (Disease) -- Patients -- Services for , HIV-positive persons -- Services for , AIDS (Disease) -- Research , AIDS (Disease) -- South Africa
- Description: The purpose of the study undertaken is to develop knowledge to assist service providers in their planning and implementation of community -based programmes and projects. The thesis explores the most appropriate way of conducting a needs assessment, relating to HIV/AIDS services in a particular community; thereafter the needs assessment was carried out. This qualitative research study is conducted using participatory methods and techniques. The research reviews literature pertaining to HIV/AIDS, specifically in Africa, South Africa and the Eastern Cape and incorporates a discussion on the concept of community, community development and poverty. The design of the needs assessment tool, implementation and analysis is conducted through focus group discussions and individual semi-structured interviews. The theory on participatory approaches and community development are central to this study. The study found that HIV / AIDS as an issue is not perceived by the community under study to be an immediate need in light of basic needs being identified as priority. The use of participatory methods in this study highlighted the diversity within communities. Service providers who wish to initiate community - based projects need to take note of diversity and personal interests of individuals or groups who become involved in community- based projects. The study further highlighted the need for service providers to provide training, to their staff in participatory approaches and techniques, before embarking on community development projects. The study concludes that services relating to the HIV/AIDS epidemic cannot be carried out in isolation, but that an integrated approach is needed in the planning and implementation of services and programmes to address those affected by HIV/AIDS.
- Full Text:
- Date Issued: 2002
Bad faith: the psychological life of a satanist who committed murder
- Authors: Du Toit, Jacobus Petrus
- Date: 2002
- Subjects: Murderers -- Psychology , Criminal psychology , Satanism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3152 , http://hdl.handle.net/10962/d1007483 , Murderers -- Psychology , Criminal psychology , Satanism
- Description: Traditional methods of psychological and forensic research fail to adequately provide an account of the psychological meaning that perpetrators of crime derive when appropriating their actions to Satanic involvement. In February 2001, a young man appeared in a South African High Court and testified that he had committed murder as a result of his involvement in Satanism. The aim of this study is to gain a phenomenological understanding of how this man appropriates the act of murder to involvement in Satanism. A review of literature elucidates Satanism as a context for meaning, provide a framework for defining murder as a criminal act, and situate this study in the broader field of phenomenological-existential, psychological research. An emergent design case-study approach was applied to data gathered from a single subject, by means of a three-interview series. An empirical phenomenological methodology was used during the interpretive phase to arrive at both a descriptive account of the subject's phenomenological experience and how the eidetic structure of the experience of Satanism as a context tor meaning emerged. A discussion of the subject's appropriation of murder with Satanism illustrates how the subject imposed a dichotomy of good and bad on his life-world in an attempt to derive meaning from his experience of inadequacy. Involvement with Satanism is meaningful, in that it affords its followers an increased sense of power, a safe environment to explore individuality, shared responsibility associated with exercising free choice, social situatedness and an affirmation of being through an increased awareness of finitude. The research subject experienced committing murder as an act of loyalty to the perceived gains he had been afforded as result of his involvement with Satanism.
- Full Text:
- Date Issued: 2002
- Authors: Du Toit, Jacobus Petrus
- Date: 2002
- Subjects: Murderers -- Psychology , Criminal psychology , Satanism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3152 , http://hdl.handle.net/10962/d1007483 , Murderers -- Psychology , Criminal psychology , Satanism
- Description: Traditional methods of psychological and forensic research fail to adequately provide an account of the psychological meaning that perpetrators of crime derive when appropriating their actions to Satanic involvement. In February 2001, a young man appeared in a South African High Court and testified that he had committed murder as a result of his involvement in Satanism. The aim of this study is to gain a phenomenological understanding of how this man appropriates the act of murder to involvement in Satanism. A review of literature elucidates Satanism as a context for meaning, provide a framework for defining murder as a criminal act, and situate this study in the broader field of phenomenological-existential, psychological research. An emergent design case-study approach was applied to data gathered from a single subject, by means of a three-interview series. An empirical phenomenological methodology was used during the interpretive phase to arrive at both a descriptive account of the subject's phenomenological experience and how the eidetic structure of the experience of Satanism as a context tor meaning emerged. A discussion of the subject's appropriation of murder with Satanism illustrates how the subject imposed a dichotomy of good and bad on his life-world in an attempt to derive meaning from his experience of inadequacy. Involvement with Satanism is meaningful, in that it affords its followers an increased sense of power, a safe environment to explore individuality, shared responsibility associated with exercising free choice, social situatedness and an affirmation of being through an increased awareness of finitude. The research subject experienced committing murder as an act of loyalty to the perceived gains he had been afforded as result of his involvement with Satanism.
- Full Text:
- Date Issued: 2002
Biological generation of reactive alkaline species and their application in a sustainable bioprocess for the remediation of acid and metal contaminated wastewaters
- Authors: Van Hille, Robert Paul
- Date: 2002
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21049 , http://hdl.handle.net/10962/6129
- Description: This project focused on the development of an integrated biological system for the treatment of acidic and metal-laden effluents, based on the sustainable biological generation of reactive alkaline species. Initial studies concentrated on the binding and accumulation of heavy metals by biomass of the cyanobacteria, Spirulina sp. Metal binding was rapid, with saturation reached in 30 minutes, and followed an affinity series of Pb > Cu > Zn >>Fe. The binding capacity of the Spirulina for each of the metals was relatively low when compared to a range of other biosorbents. The toxicity thresholds of the algae was determined for copper and zinc. These were low (10umoles/g) and as such, the algae were not suitable for application in a treatment system in which they came into direct contact with the toxic metals. The algae were able to increase the pH of the surrounding medium. This occurred as a result of the accumulation of inorganic carbon, from bicarbonate, as a response to low concentrations of carbon dioxide in the medium. The resulting release of a hydroxide ion into solution led to the increase in pH. The increase in pH was shown to be due to a reduction in acidity, rather than an increase in alkalinity. The enzyme carbonic anhydrase was shown to be pivotal in this system. Attempts to determine the enzyme activity directly were unsuccessful, due to the inherent inaccuracy of the assay system. An indirect method of determining enzyme activity, by measuring changes in the carbonate species equilibrium, was developed. Under optimal conditions Spirulina was able to reduce the acidity by an amount equivalent to the addition of 3670umoles NaOH g·' h·'. Predictive modelling showed that this enhanced the potential of the medium to effect metal precipitation. For the algal system to be sustainable, a readily available source of bicarbonate was needed. This was achieved by the oxidation of organic carbon, under sulphidogenic conditions, by a bacterial consortium isolated from the anaerobic component of a facultative pond. The consortium was shown to consist of sulphate reducing (most likely Desulvovibrio and Desulfotomaculum)and acetogenic bacteria. Sulphate removal rates of 500mg 1·' day·' and 135mg 1·' day·' were achieved in a 21 agitated and 281 upflow reactor respectively. The bicarbonate generation rate in the 281 reactor was calculated as 4033umoles 1·' day·', which proved sufficient to act as a feed for the algal system. Sparging the anaerobic digester overflow with air and nitrogen resulted in a reduction in the aqueous sulphide concentration. Using nitrogen, a 70% recovery of sulphide, as H2S gas, was achieved in 60 minutes, while with air, this dropped to 40%, due to the oxidation of the aqueous sulphide. The stripping ofH2S resulted in an increase in pH. The H2S gas was used for the selective precipitation of copper and lead in the integrated system. The dynamics of metal precipitation was investigated. For simple reactions, between individual IV metal and base species, it was possible to generate an accurate predictive model and confirm the precipitating species using wavelength dispersive X-ray spectroscopy (WDS). In more complex systems, where precipitation of the artificial acid mine drainage was examined, the predictive modelling and WDS could not accurately describe the system. The addition of aqueous sulphide to copper and iron resulted in the formation of metastable, amorphous precipitates, which remained in suspension. Ageing of the copper precipitate resulted in the evolution of a stable crystalline structure (covellite) and the aggregation and settling of the precipitate. In the case of iron, the amorphous precipitate underwent oxidation before a stable iron sulphide could evolve and the settled precipitate was an iron oxide or oxyhydroxide. The artificial acid mine drainage was treated with sulphide, hydroxide, anaerobic digester overflow and algal overflow. The best metal removal was achieved with the sulphide and hydroxide, while the algal overflow outperformed the anaerobic digester overflow. The precipitate generated by the addition of sulphide was the most compact, followed by the algal overflow, the anaerobic digester overflow and the hydroxide. Efficient precipitation of all the heavy metals, except manganese, was achieved using the algal overflow at an acidity to alkalinity ratio of 1 :2. This ratio was selected for use in the pilot system. The Spirulina based pilot system was effectively used to treat an effluent from the Black Mountain base metal mine. The necessity to maintain the algae in suspension and avoid biomass washout were practical considerations which counted against this system. The replacement of the Spirulina by Oscillatoria, which adhered to a solid support, overcame these problems. The integrated biological system was able to effectively treat an artificial acid mine drainage for 90 days, reducing the concentration of all metals, except manganese, to below the acceptable environmental risk levels. The treatment of the final effluent in a second anaerobic digester reduced the manganese concentration to 4.5uM and proved that the sulphate reducing bacteria could be cultivated on enriched, partially treated acid mine drainage. The integrated biological treatment system performed well, effectively treating an effluent modelled closely on the quality of the water being discharged from the East Rand Basin. The cost of such a system would be considerably less than a "high tech" physico-chemical system. This, coupled with the potential long term sustainability of a biological system, would make it a potentially attractive option for the treatment of future acid mine drainage discharges.
- Full Text:
- Date Issued: 2002
- Authors: Van Hille, Robert Paul
- Date: 2002
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21049 , http://hdl.handle.net/10962/6129
- Description: This project focused on the development of an integrated biological system for the treatment of acidic and metal-laden effluents, based on the sustainable biological generation of reactive alkaline species. Initial studies concentrated on the binding and accumulation of heavy metals by biomass of the cyanobacteria, Spirulina sp. Metal binding was rapid, with saturation reached in 30 minutes, and followed an affinity series of Pb > Cu > Zn >>Fe. The binding capacity of the Spirulina for each of the metals was relatively low when compared to a range of other biosorbents. The toxicity thresholds of the algae was determined for copper and zinc. These were low (10umoles/g) and as such, the algae were not suitable for application in a treatment system in which they came into direct contact with the toxic metals. The algae were able to increase the pH of the surrounding medium. This occurred as a result of the accumulation of inorganic carbon, from bicarbonate, as a response to low concentrations of carbon dioxide in the medium. The resulting release of a hydroxide ion into solution led to the increase in pH. The increase in pH was shown to be due to a reduction in acidity, rather than an increase in alkalinity. The enzyme carbonic anhydrase was shown to be pivotal in this system. Attempts to determine the enzyme activity directly were unsuccessful, due to the inherent inaccuracy of the assay system. An indirect method of determining enzyme activity, by measuring changes in the carbonate species equilibrium, was developed. Under optimal conditions Spirulina was able to reduce the acidity by an amount equivalent to the addition of 3670umoles NaOH g·' h·'. Predictive modelling showed that this enhanced the potential of the medium to effect metal precipitation. For the algal system to be sustainable, a readily available source of bicarbonate was needed. This was achieved by the oxidation of organic carbon, under sulphidogenic conditions, by a bacterial consortium isolated from the anaerobic component of a facultative pond. The consortium was shown to consist of sulphate reducing (most likely Desulvovibrio and Desulfotomaculum)and acetogenic bacteria. Sulphate removal rates of 500mg 1·' day·' and 135mg 1·' day·' were achieved in a 21 agitated and 281 upflow reactor respectively. The bicarbonate generation rate in the 281 reactor was calculated as 4033umoles 1·' day·', which proved sufficient to act as a feed for the algal system. Sparging the anaerobic digester overflow with air and nitrogen resulted in a reduction in the aqueous sulphide concentration. Using nitrogen, a 70% recovery of sulphide, as H2S gas, was achieved in 60 minutes, while with air, this dropped to 40%, due to the oxidation of the aqueous sulphide. The stripping ofH2S resulted in an increase in pH. The H2S gas was used for the selective precipitation of copper and lead in the integrated system. The dynamics of metal precipitation was investigated. For simple reactions, between individual IV metal and base species, it was possible to generate an accurate predictive model and confirm the precipitating species using wavelength dispersive X-ray spectroscopy (WDS). In more complex systems, where precipitation of the artificial acid mine drainage was examined, the predictive modelling and WDS could not accurately describe the system. The addition of aqueous sulphide to copper and iron resulted in the formation of metastable, amorphous precipitates, which remained in suspension. Ageing of the copper precipitate resulted in the evolution of a stable crystalline structure (covellite) and the aggregation and settling of the precipitate. In the case of iron, the amorphous precipitate underwent oxidation before a stable iron sulphide could evolve and the settled precipitate was an iron oxide or oxyhydroxide. The artificial acid mine drainage was treated with sulphide, hydroxide, anaerobic digester overflow and algal overflow. The best metal removal was achieved with the sulphide and hydroxide, while the algal overflow outperformed the anaerobic digester overflow. The precipitate generated by the addition of sulphide was the most compact, followed by the algal overflow, the anaerobic digester overflow and the hydroxide. Efficient precipitation of all the heavy metals, except manganese, was achieved using the algal overflow at an acidity to alkalinity ratio of 1 :2. This ratio was selected for use in the pilot system. The Spirulina based pilot system was effectively used to treat an effluent from the Black Mountain base metal mine. The necessity to maintain the algae in suspension and avoid biomass washout were practical considerations which counted against this system. The replacement of the Spirulina by Oscillatoria, which adhered to a solid support, overcame these problems. The integrated biological system was able to effectively treat an artificial acid mine drainage for 90 days, reducing the concentration of all metals, except manganese, to below the acceptable environmental risk levels. The treatment of the final effluent in a second anaerobic digester reduced the manganese concentration to 4.5uM and proved that the sulphate reducing bacteria could be cultivated on enriched, partially treated acid mine drainage. The integrated biological treatment system performed well, effectively treating an effluent modelled closely on the quality of the water being discharged from the East Rand Basin. The cost of such a system would be considerably less than a "high tech" physico-chemical system. This, coupled with the potential long term sustainability of a biological system, would make it a potentially attractive option for the treatment of future acid mine drainage discharges.
- Full Text:
- Date Issued: 2002
Biological sulphide oxidation in heterotrophic environments
- Authors: Rein, Neil Berthold
- Date: 2002
- Subjects: Acid mine drainage , Oxidation , Sulfides , Oxidation, Physiological
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3919 , http://hdl.handle.net/10962/d1003978 , Acid mine drainage , Oxidation , Sulfides , Oxidation, Physiological
- Description: Acid mine drainage is a major environmental pollution concern associated with the mining of sulphide-containing ore bodies. Both physicochemical and biological options have been investigated for the treatment of acid mine drainage with recent interest in biological processes targeting low-cost and passive treatment applications. All acid mine drainage biological treatment processes are based to some extent on the activity of sulphate reducing bacteria, and their ability to reduce sulphate to sulphide in the presence of a range of carbon and electron donor sources. A portion of the sulphide produced may be consumed in the precipitation of heavy metals present in the mine drainage. Residual sulphide must be removed, not only due to its toxicity, but especially to prevent its reoxidation to sulphate where salinity reduction is a target of the treatment process. The partial oxidation of sulphide to elemental sulphur is an option that has received considerable attention and both physicochemical and biological options have been investigated. Biological processes have substantial potential cost advantages and run at ambient temperatures and pressures. However, the oxidation of sulphide to elemental sulphur is poised over a narrow redox range and process control to maintain optimum conditions remains a serious problem. In addition little has been reported in the literature on process control of sulphide oxidation to elemental sulphur, in the heterotrophic conditions prevailing in the reaction environment following sulphate reduction. This study undertook an investigation of biological sulphide oxidation under heterotrophic conditions in order to establish the effect of organic compounds on biological sulphide oxidation, and to determine whether the presence of organics, and associated heterotrophic oxygen consumption, may be manipulated to maintain the defined redox conditions required for the production of elemental sulphur. Biological sulphide oxidation under heterotrophic conditions was investigated in a series of flask experiments. Based on these results three different reactor configurations, a Fixed-Film Trickle Filter Reactor, Submerged Fixed-Film Reactor and a Silicone Tubular Reactor were used to investigate sulphur production. The flask studies indicated that organics, and associated heterotrophic metabolism in the presence of excess oxygen in the sulphide oxidation reaction environment, did contribute to the poising of redox conditions and thereby enabling the production of elemental sulphur. While the Fixed-Film Trickle Filter Reactor was found to be redox unstable, probably due to excess oxygen ingress to the system, a reduced oxygen challenge in the Submerged Fixed-Film Reactor configuration was found to be more successful for production of elemental sulphur. However, due to the production of a predominantly filamentous sulphur producing microbial population, recovery of sulphur from the column was intermittent and unpredictable. Extended residence times for produced sulphur on the column increased the likelihood for its eventual oxidation to sulphate. The Silicone Tubular Reactor was found to support a vigorous sulphide oxidising biofilm and produced elemental sulphur effectively. Electron microscopic studies showed that this occurred as both biologically produced sulphur and, probably mainly, as crystalline sulphur in the ortho-rhomic form. Given the linear extension of the sulphur production reaction environment it is was possible to investigate the sequence of the reaction mechanism in grater detail than is possible in mixed systems. Based on these findings a model explaining sulphur production under heterotrophic conditions has been proposed and is presented. The commercial implications of the development have also been noted.
- Full Text:
- Date Issued: 2002
- Authors: Rein, Neil Berthold
- Date: 2002
- Subjects: Acid mine drainage , Oxidation , Sulfides , Oxidation, Physiological
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3919 , http://hdl.handle.net/10962/d1003978 , Acid mine drainage , Oxidation , Sulfides , Oxidation, Physiological
- Description: Acid mine drainage is a major environmental pollution concern associated with the mining of sulphide-containing ore bodies. Both physicochemical and biological options have been investigated for the treatment of acid mine drainage with recent interest in biological processes targeting low-cost and passive treatment applications. All acid mine drainage biological treatment processes are based to some extent on the activity of sulphate reducing bacteria, and their ability to reduce sulphate to sulphide in the presence of a range of carbon and electron donor sources. A portion of the sulphide produced may be consumed in the precipitation of heavy metals present in the mine drainage. Residual sulphide must be removed, not only due to its toxicity, but especially to prevent its reoxidation to sulphate where salinity reduction is a target of the treatment process. The partial oxidation of sulphide to elemental sulphur is an option that has received considerable attention and both physicochemical and biological options have been investigated. Biological processes have substantial potential cost advantages and run at ambient temperatures and pressures. However, the oxidation of sulphide to elemental sulphur is poised over a narrow redox range and process control to maintain optimum conditions remains a serious problem. In addition little has been reported in the literature on process control of sulphide oxidation to elemental sulphur, in the heterotrophic conditions prevailing in the reaction environment following sulphate reduction. This study undertook an investigation of biological sulphide oxidation under heterotrophic conditions in order to establish the effect of organic compounds on biological sulphide oxidation, and to determine whether the presence of organics, and associated heterotrophic oxygen consumption, may be manipulated to maintain the defined redox conditions required for the production of elemental sulphur. Biological sulphide oxidation under heterotrophic conditions was investigated in a series of flask experiments. Based on these results three different reactor configurations, a Fixed-Film Trickle Filter Reactor, Submerged Fixed-Film Reactor and a Silicone Tubular Reactor were used to investigate sulphur production. The flask studies indicated that organics, and associated heterotrophic metabolism in the presence of excess oxygen in the sulphide oxidation reaction environment, did contribute to the poising of redox conditions and thereby enabling the production of elemental sulphur. While the Fixed-Film Trickle Filter Reactor was found to be redox unstable, probably due to excess oxygen ingress to the system, a reduced oxygen challenge in the Submerged Fixed-Film Reactor configuration was found to be more successful for production of elemental sulphur. However, due to the production of a predominantly filamentous sulphur producing microbial population, recovery of sulphur from the column was intermittent and unpredictable. Extended residence times for produced sulphur on the column increased the likelihood for its eventual oxidation to sulphate. The Silicone Tubular Reactor was found to support a vigorous sulphide oxidising biofilm and produced elemental sulphur effectively. Electron microscopic studies showed that this occurred as both biologically produced sulphur and, probably mainly, as crystalline sulphur in the ortho-rhomic form. Given the linear extension of the sulphur production reaction environment it is was possible to investigate the sequence of the reaction mechanism in grater detail than is possible in mixed systems. Based on these findings a model explaining sulphur production under heterotrophic conditions has been proposed and is presented. The commercial implications of the development have also been noted.
- Full Text:
- Date Issued: 2002
Biosulphidogenic hydrolysis of lignin and lignin model compounds
- Authors: Madikane, Mzekelo
- Date: 2002
- Subjects: Lignin Lignin -- Biodegradation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3917 , http://hdl.handle.net/10962/d1003976
- Description: Lignin degradation under biosulphidogenic conditions has not been extensively reported in the literature. Although aerobic degradation of lignin is well documented, anaerobic biodegradation has focused mainly on methanogenic systems with biosulphidogenic systems receiving less attention. Sulphate reducing bacteria are known to generate moderately high levels of both sulphide and alkalinity at room temperatures, and these conditions draw some comparison with the Kraft pulping process. In the Kraft pulping process, lignin is degraded chemically at ±170°C under high sulphide and alkaline conditions and may provide a model for understanding biosulphidogenic lignin degrading activity. The aim of this study was to investigate the biosulphidogenic hydrolysis of lignin within the context of the chemical and biological conditions generated by a mixed sulphate reducing bacteria consortia. Bioreactor studies with a mixed sulphate reducing consortia and pine wood powder (both untreated and depectinated) resulted in the generation of comparable levels of sulphide and alkalinity used in the chemical hydrolysis studies. Aromatic compound yields were between 20 to 50% of the chemical hydrolysis studies. This fluctuation may have been due to the utilization of these aromatic compounds as electron donors by the sulphate reducing consortia as evidenced by the high rate of sulphate reduction in both the untreated and depectinated wood bioreactors. Biodegradation of lignin model compounds was investigated in order to elucidate lignin degradation mechanisms. Both mono-aromatic and dimeric lignin model compounds were used as electron donors and carbon sources for the mixed sulphate reducing consortia. Biodegradation and mass spectrometer analysis of mono-aromatic compounds, ferulic acid and ferulic acid ethyl ester resulted in the production of intermediates such as catechol, cyclohexane carboxylic acid and adipic acid. These intermediates were also observed in the degradation of dimeric ferulic acid. Biodegradation of salicin resulted in the production of salicyl alcohol, ortho-cresol and acetate. Biodegradation of benzylic ether resulted in the production of vanillin and acetate as end products. The results of these studies provide evidence for a biosulphidogenic hydrolysis of lignin, and also the utilisation of lignin-derived aromatic compounds as electron donor sources, by a mixed sulphate reducing consortia.
- Full Text:
- Date Issued: 2002
- Authors: Madikane, Mzekelo
- Date: 2002
- Subjects: Lignin Lignin -- Biodegradation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3917 , http://hdl.handle.net/10962/d1003976
- Description: Lignin degradation under biosulphidogenic conditions has not been extensively reported in the literature. Although aerobic degradation of lignin is well documented, anaerobic biodegradation has focused mainly on methanogenic systems with biosulphidogenic systems receiving less attention. Sulphate reducing bacteria are known to generate moderately high levels of both sulphide and alkalinity at room temperatures, and these conditions draw some comparison with the Kraft pulping process. In the Kraft pulping process, lignin is degraded chemically at ±170°C under high sulphide and alkaline conditions and may provide a model for understanding biosulphidogenic lignin degrading activity. The aim of this study was to investigate the biosulphidogenic hydrolysis of lignin within the context of the chemical and biological conditions generated by a mixed sulphate reducing bacteria consortia. Bioreactor studies with a mixed sulphate reducing consortia and pine wood powder (both untreated and depectinated) resulted in the generation of comparable levels of sulphide and alkalinity used in the chemical hydrolysis studies. Aromatic compound yields were between 20 to 50% of the chemical hydrolysis studies. This fluctuation may have been due to the utilization of these aromatic compounds as electron donors by the sulphate reducing consortia as evidenced by the high rate of sulphate reduction in both the untreated and depectinated wood bioreactors. Biodegradation of lignin model compounds was investigated in order to elucidate lignin degradation mechanisms. Both mono-aromatic and dimeric lignin model compounds were used as electron donors and carbon sources for the mixed sulphate reducing consortia. Biodegradation and mass spectrometer analysis of mono-aromatic compounds, ferulic acid and ferulic acid ethyl ester resulted in the production of intermediates such as catechol, cyclohexane carboxylic acid and adipic acid. These intermediates were also observed in the degradation of dimeric ferulic acid. Biodegradation of salicin resulted in the production of salicyl alcohol, ortho-cresol and acetate. Biodegradation of benzylic ether resulted in the production of vanillin and acetate as end products. The results of these studies provide evidence for a biosulphidogenic hydrolysis of lignin, and also the utilisation of lignin-derived aromatic compounds as electron donor sources, by a mixed sulphate reducing consortia.
- Full Text:
- Date Issued: 2002
Broken vessels : the im-possibility of the art of remembrance and re-collection in the work of Anselm Kiefer, Christian Boltanski, William Kentridge and Santu Mofokeng
- Authors: Belluigi, Dina Zoe
- Date: 2002
- Subjects: History in art Kiefer, Anselm, 1945- Boltanski, Christian, 1944- Kentridge, William, 1955- Mofokeng, Santu, 1956-
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2395 , http://hdl.handle.net/10962/d1002191
- Description: This thesis is structured around investigating the philosophical and aesthetic problematics, politics, and possibilities of representing the past for the purposes of demythifying the present as well as commemorating the losses of history, as explored in the artworks of Anselm Kiefer, Christian Boltanski, William Kentridge and Santu Mofokeng. The first chapter begins with Theodor Adorno’s philosophical understanding of myth and history: how he is influenced by and then develops Karl Marx’s critique of society, Sigmund Freud’s critique of reason and its subject, and particularly Walter Benjamin’s ideas of history as catastrophe, the role of the historian and his messianic materialism. The second section looks at Theodor Adorno’s dialectic of art and society: immanent criticism in aesthetic practice, mimesis, and the shift in conceptions of allegory from Walter Benjamin’s understanding to that of Jacques Derrida. The last section of the chapter looks at Jacques Derrida’s poststructuralist theories against boundary-fixing, within that the ethical relation to the ‘other’ and the theorist/artist as psychic exile. The second chapter deals with the politics of remembrance and representation — beginning with Theodor Adorno’s historic interpretation of the Mosaic law against the making of images and Jean-Francois Lyotard on the im-possibility of representing the unrepresentable. The chapter is divided in two parts between the post-Holocaust European artists Anselm Kiefer and Christian Boltanski, and the post-apartheid South African artists William Kentridge and Santu Mofokeng. It explores, within these artists’ specific contexts, their formal and philosophical approaches to myth and history, and the problematics of image-making, representing the unrepresentable, and commemorating the immemorial. The thesis concludes by considering different conceptions of melancholia as they relate to these artists: the Freudian psychoanalytic approach, Benjamin’s notions of the artist-genius, and Julia Kristeva’s Lacanian reading of the humanist melancholic, concluding with the mythic-historical Kaballist notion of melancholia as the historical burden or responsibility to commemorate loss.
- Full Text:
- Date Issued: 2002
- Authors: Belluigi, Dina Zoe
- Date: 2002
- Subjects: History in art Kiefer, Anselm, 1945- Boltanski, Christian, 1944- Kentridge, William, 1955- Mofokeng, Santu, 1956-
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2395 , http://hdl.handle.net/10962/d1002191
- Description: This thesis is structured around investigating the philosophical and aesthetic problematics, politics, and possibilities of representing the past for the purposes of demythifying the present as well as commemorating the losses of history, as explored in the artworks of Anselm Kiefer, Christian Boltanski, William Kentridge and Santu Mofokeng. The first chapter begins with Theodor Adorno’s philosophical understanding of myth and history: how he is influenced by and then develops Karl Marx’s critique of society, Sigmund Freud’s critique of reason and its subject, and particularly Walter Benjamin’s ideas of history as catastrophe, the role of the historian and his messianic materialism. The second section looks at Theodor Adorno’s dialectic of art and society: immanent criticism in aesthetic practice, mimesis, and the shift in conceptions of allegory from Walter Benjamin’s understanding to that of Jacques Derrida. The last section of the chapter looks at Jacques Derrida’s poststructuralist theories against boundary-fixing, within that the ethical relation to the ‘other’ and the theorist/artist as psychic exile. The second chapter deals with the politics of remembrance and representation — beginning with Theodor Adorno’s historic interpretation of the Mosaic law against the making of images and Jean-Francois Lyotard on the im-possibility of representing the unrepresentable. The chapter is divided in two parts between the post-Holocaust European artists Anselm Kiefer and Christian Boltanski, and the post-apartheid South African artists William Kentridge and Santu Mofokeng. It explores, within these artists’ specific contexts, their formal and philosophical approaches to myth and history, and the problematics of image-making, representing the unrepresentable, and commemorating the immemorial. The thesis concludes by considering different conceptions of melancholia as they relate to these artists: the Freudian psychoanalytic approach, Benjamin’s notions of the artist-genius, and Julia Kristeva’s Lacanian reading of the humanist melancholic, concluding with the mythic-historical Kaballist notion of melancholia as the historical burden or responsibility to commemorate loss.
- Full Text:
- Date Issued: 2002
Case studies of equivalent fuzzy subgroups of finite abelian groups
- Authors: Ngcibi, Sakhile L
- Date: 2002
- Subjects: Abelian groups , Fuzzy sets
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5401 , http://hdl.handle.net/10962/d1005215 , Abelian groups , Fuzzy sets
- Description: The broad goal is to classify all fuzzy subgroups of a given type of finite group. P.S. Das introduced the ntion of level subgroups to characterize fuzzy subgroups of finite grouops. The notion of equivalence of fuzzy subgroups which is used in this thesis was first introduced by Murali and Makamba. We use this equivalence to charterise fuzzy subgroups of inite Abelian groups (p-groups in particular) for a specified prime p. We characterize some crisp subgroups of p-groups and investigate some cases on equi valent fuzzy subgroups.
- Full Text:
- Date Issued: 2002
- Authors: Ngcibi, Sakhile L
- Date: 2002
- Subjects: Abelian groups , Fuzzy sets
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5401 , http://hdl.handle.net/10962/d1005215 , Abelian groups , Fuzzy sets
- Description: The broad goal is to classify all fuzzy subgroups of a given type of finite group. P.S. Das introduced the ntion of level subgroups to characterize fuzzy subgroups of finite grouops. The notion of equivalence of fuzzy subgroups which is used in this thesis was first introduced by Murali and Makamba. We use this equivalence to charterise fuzzy subgroups of inite Abelian groups (p-groups in particular) for a specified prime p. We characterize some crisp subgroups of p-groups and investigate some cases on equi valent fuzzy subgroups.
- Full Text:
- Date Issued: 2002
Catalytic behaviour of metallophthalocyanines towards the detection of nitric oxide
- Authors: Vilakazi, Lea Sibulelo
- Date: 2002
- Subjects: Electrochemistry Nitric oxide
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4418 , http://hdl.handle.net/10962/d1006852
- Description: Electrocatalytic reduction and oxidation of nitric oxide (NO) using cobalt phthalocyanine complexes have been studied and compared to vitamin B₁₂ and other metallophthalocyanine (MPc) complexes. Modifying a glassy carbon electrode with these complexes resulted in improved sensitivity of the electrode allowing detection of NO to 10⁻⁹ mol dm⁻³. The mechanisms of catalysis were studied. Electrocatalysis of NO involves coordination of NO to the MPc complex. Hence catalytic activity is affected by the nature of the metal center. However coordination of NO to the MPc complex has to be reversible to eliminate poisoning of the electrode. Though FePc gave the best sensitivity and lowered the reduction potential more than CoPc, the strong Fe-NO bond resulted in the poisoning of the electrode hence, rendering the electrode unstable. Rate constants for NO coordination to the MPc complexes were studied. These rates were smaller than the studied NO porphyrin coordination rates. Electrocatalytic reduction of NO using MPc complexes involves a transfer of an electron from the metal center to the NO ligand. Hence, substitution of electron-donating grohps on the cobalt pthalocyanine complex resulted in improved sensitivity and catalytic activity. A CoPc modified microelectrode (11μm) was used to monitor NO in human blood components and to detect NO in a rat brain. Detections of NO were also done in aqueous solutions in the presence of interfering species such as dopamine and serotonin. An interaction between NO and serotonin was observed.
- Full Text:
- Date Issued: 2002
- Authors: Vilakazi, Lea Sibulelo
- Date: 2002
- Subjects: Electrochemistry Nitric oxide
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4418 , http://hdl.handle.net/10962/d1006852
- Description: Electrocatalytic reduction and oxidation of nitric oxide (NO) using cobalt phthalocyanine complexes have been studied and compared to vitamin B₁₂ and other metallophthalocyanine (MPc) complexes. Modifying a glassy carbon electrode with these complexes resulted in improved sensitivity of the electrode allowing detection of NO to 10⁻⁹ mol dm⁻³. The mechanisms of catalysis were studied. Electrocatalysis of NO involves coordination of NO to the MPc complex. Hence catalytic activity is affected by the nature of the metal center. However coordination of NO to the MPc complex has to be reversible to eliminate poisoning of the electrode. Though FePc gave the best sensitivity and lowered the reduction potential more than CoPc, the strong Fe-NO bond resulted in the poisoning of the electrode hence, rendering the electrode unstable. Rate constants for NO coordination to the MPc complexes were studied. These rates were smaller than the studied NO porphyrin coordination rates. Electrocatalytic reduction of NO using MPc complexes involves a transfer of an electron from the metal center to the NO ligand. Hence, substitution of electron-donating grohps on the cobalt pthalocyanine complex resulted in improved sensitivity and catalytic activity. A CoPc modified microelectrode (11μm) was used to monitor NO in human blood components and to detect NO in a rat brain. Detections of NO were also done in aqueous solutions in the presence of interfering species such as dopamine and serotonin. An interaction between NO and serotonin was observed.
- Full Text:
- Date Issued: 2002
Chemical studies of selected chromone derivatives
- Authors: Nchinda, Aloysius Tchangwe
- Date: 2002
- Subjects: Heterocyclic compounds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4434 , http://hdl.handle.net/10962/d1007442
- Description: This investigation has been geared towards several aspects of chromone chemistry. Selected 2-(N,N-dimethylarnino)chromones have been synthesized via 2-hydroxyacetophenone boron difluoride complex intermediates, and potentiometric analysis of these compounds in ethanolwater has been used to determine the influence of substituents on their basicity. The pKa values have been found to lie within a narrow range (1.92 - 2.52), and the observed substituent effects have been rationalized with the aid of semi-empirical and ab initio molecular orbital calculations. An efficient route has been developed for the synthesis of the naturally-occurring chromone, "granulosin" [7,8-(methylenedioxy)-2-propylchromone], and several C-2 side chain analogues in good yields, by condensing 2'-hydroxy-3',4'-(methylenedioxy)acetophenone with a range of ethyl carboxylate esters. These compounds show significant cytotoxic activity against the brine shrimp, Artemia salina, and two of them, the 2-ethyl and 2-benzyl derivatives also show 100% activity as pesticides on Beet army worms (BAW). Another naturally-occurring chromone derivative, 5-hydroxy-2-isopropyl-7-methoxychromone, and four C-2 side chain analogues have been prepared in moderate yields. These compounds also show significant cytotoxic activity against the brine shrimp, Artemia salina, and it is apparent that the presence of the hydroxyl group at C-5 is critical for such activity. The electronimpact mass spectra of both series of chromone derivatives have been investigated, permitting the elucidation of characteristic fragmentation patterns. In work directed towards the synthesis of potential HIV -1 protease inhibitors, five novel chromone-containing analogues of the clinically useful drug, ritonavir, have been synthesized. The design strategy has involved the coupling of substituted chromone-2- carboxylic acids with a specially prepared, hydroxyethylene dipeptide isostere to afford ritonavir analogues containing chromone termini. An interactive docking procedure has been used to explore the docking of ritonavir and the novel chromone-containing analogues into ' the active site of the enzyme, and has indicated the capacity of the ritonavir analogues to form hydrogen-bonds with the HJV-l enzyme receptor. Various substituted cbromone-3-carbaldehydes, which have been synthesized from the corresponding o-hyclroxyacetophenones using Vilsmeier-Haack methodology, have been examined as substrates for Morita-Baylis-Hillman reactions, using 3-hyclroxyquinuclidine as the catalyst and arcylonitrile and methyl acrylate as the activated alkenes. Optimization of the reaction conditions has permitted efficient conversion of the cbromone-3-carbaldehydes to the Morita-Baylis-Hillman products and, in some cases, dimeric products, within 24 h. Heating of the Morita-Baylis-Hillman products, arising from reactions with methyl acrylate, at 80 ºC for 3 h in the presence of DABCO as catalyst, has been shown to effect transformation to the corresponding dimers in good yield.
- Full Text:
- Date Issued: 2002
- Authors: Nchinda, Aloysius Tchangwe
- Date: 2002
- Subjects: Heterocyclic compounds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4434 , http://hdl.handle.net/10962/d1007442
- Description: This investigation has been geared towards several aspects of chromone chemistry. Selected 2-(N,N-dimethylarnino)chromones have been synthesized via 2-hydroxyacetophenone boron difluoride complex intermediates, and potentiometric analysis of these compounds in ethanolwater has been used to determine the influence of substituents on their basicity. The pKa values have been found to lie within a narrow range (1.92 - 2.52), and the observed substituent effects have been rationalized with the aid of semi-empirical and ab initio molecular orbital calculations. An efficient route has been developed for the synthesis of the naturally-occurring chromone, "granulosin" [7,8-(methylenedioxy)-2-propylchromone], and several C-2 side chain analogues in good yields, by condensing 2'-hydroxy-3',4'-(methylenedioxy)acetophenone with a range of ethyl carboxylate esters. These compounds show significant cytotoxic activity against the brine shrimp, Artemia salina, and two of them, the 2-ethyl and 2-benzyl derivatives also show 100% activity as pesticides on Beet army worms (BAW). Another naturally-occurring chromone derivative, 5-hydroxy-2-isopropyl-7-methoxychromone, and four C-2 side chain analogues have been prepared in moderate yields. These compounds also show significant cytotoxic activity against the brine shrimp, Artemia salina, and it is apparent that the presence of the hydroxyl group at C-5 is critical for such activity. The electronimpact mass spectra of both series of chromone derivatives have been investigated, permitting the elucidation of characteristic fragmentation patterns. In work directed towards the synthesis of potential HIV -1 protease inhibitors, five novel chromone-containing analogues of the clinically useful drug, ritonavir, have been synthesized. The design strategy has involved the coupling of substituted chromone-2- carboxylic acids with a specially prepared, hydroxyethylene dipeptide isostere to afford ritonavir analogues containing chromone termini. An interactive docking procedure has been used to explore the docking of ritonavir and the novel chromone-containing analogues into ' the active site of the enzyme, and has indicated the capacity of the ritonavir analogues to form hydrogen-bonds with the HJV-l enzyme receptor. Various substituted cbromone-3-carbaldehydes, which have been synthesized from the corresponding o-hyclroxyacetophenones using Vilsmeier-Haack methodology, have been examined as substrates for Morita-Baylis-Hillman reactions, using 3-hyclroxyquinuclidine as the catalyst and arcylonitrile and methyl acrylate as the activated alkenes. Optimization of the reaction conditions has permitted efficient conversion of the cbromone-3-carbaldehydes to the Morita-Baylis-Hillman products and, in some cases, dimeric products, within 24 h. Heating of the Morita-Baylis-Hillman products, arising from reactions with methyl acrylate, at 80 ºC for 3 h in the presence of DABCO as catalyst, has been shown to effect transformation to the corresponding dimers in good yield.
- Full Text:
- Date Issued: 2002
Continuity and generalized continuity in dynamics and other applications
- Authors: Mimna, Roy Allan
- Date: 2002
- Subjects: Topological dynamics -- Research Dynamics -- Mathematical models -- Research Perturbation (Mathematics) Attractors (Mathematics) Baire classes Mathematics -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5404 , http://hdl.handle.net/10962/d1005218
- Description: The topological dynamics of continuous and noncontinuous dynamical systems are investigated. Various definitions of chaos are studied, as well as notions of stability. Results are obtained on asymptotically stable sets and the perturbation stability of such sets. The primary focus is on the traditional point sets of topological dynamics, including the chain recurrent set, omega-limit sets and attractors. The basic setting is that of a continuous function on a compact metric space, sometimes with additional properties on the space. The investigation includes results on the dynamical properties of typical continuous functions in the sense of Baire category. Results are also developed concerning dynamical systems involving quasi-continuous functions. An invariance property for the omega-limit sets of such functions is given. Omega-limit sets are characterized for Riemann integrable derivatives and derivatiyes which are continuous almost everywhere. Techniques used in the investigation and formulation of results include finding theorems which relate the rather disparate notions of dynamical properties and generalized continuity. In addition to dynamical systems, numerous other applications of generalized continuity are imoestigated. Techniques used include application of the Baire Category Theorem and the notion of semi-closure. For example, results are formulated concerning functions determined by dense sets, including separately continuous functions, thus generalizing the classical result for continuous functions on dense subsets of the domain. The uniform boundedness theorem is extended to functions which are not necessarily continuous, including various derivatives. The closed graph theorem is strictly generalized in two separate ways, and applications are presented using these generalizations. An invariance property of separately continuous functions is given. Cluster sets are studied in connection with separate continuity, and various results are presented concerning locally bounded functions.
- Full Text:
- Date Issued: 2002
- Authors: Mimna, Roy Allan
- Date: 2002
- Subjects: Topological dynamics -- Research Dynamics -- Mathematical models -- Research Perturbation (Mathematics) Attractors (Mathematics) Baire classes Mathematics -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5404 , http://hdl.handle.net/10962/d1005218
- Description: The topological dynamics of continuous and noncontinuous dynamical systems are investigated. Various definitions of chaos are studied, as well as notions of stability. Results are obtained on asymptotically stable sets and the perturbation stability of such sets. The primary focus is on the traditional point sets of topological dynamics, including the chain recurrent set, omega-limit sets and attractors. The basic setting is that of a continuous function on a compact metric space, sometimes with additional properties on the space. The investigation includes results on the dynamical properties of typical continuous functions in the sense of Baire category. Results are also developed concerning dynamical systems involving quasi-continuous functions. An invariance property for the omega-limit sets of such functions is given. Omega-limit sets are characterized for Riemann integrable derivatives and derivatiyes which are continuous almost everywhere. Techniques used in the investigation and formulation of results include finding theorems which relate the rather disparate notions of dynamical properties and generalized continuity. In addition to dynamical systems, numerous other applications of generalized continuity are imoestigated. Techniques used include application of the Baire Category Theorem and the notion of semi-closure. For example, results are formulated concerning functions determined by dense sets, including separately continuous functions, thus generalizing the classical result for continuous functions on dense subsets of the domain. The uniform boundedness theorem is extended to functions which are not necessarily continuous, including various derivatives. The closed graph theorem is strictly generalized in two separate ways, and applications are presented using these generalizations. An invariance property of separately continuous functions is given. Cluster sets are studied in connection with separate continuity, and various results are presented concerning locally bounded functions.
- Full Text:
- Date Issued: 2002
Convergence of old and new: a case study analysis of the development online by a South African radio station: Radiosondergrense/www.rsg.co.za
- Authors: Vasques, Vanessa Claudia
- Date: 2002
- Subjects: Radio stations -- South Africa , Radio stations -- South Africa -- Marketing , Radio stations -- Computer network resources , Radiosondergrense
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3498 , http://hdl.handle.net/10962/d1003913 , Radio stations -- South Africa , Radio stations -- South Africa -- Marketing , Radio stations -- Computer network resources , Radiosondergrense
- Description: This thesis is a case study analysis of the dream one radio station had about creating something new and unique on the Internet. RadioSonderGrense (RSG), an Afrikaans South African radio station, saw opportunities for themselves as a radio station on the Internet and put enormous resources and man-power into their venture. Their vision of what the Internet could bring to their radio station, and what they could bring to a website set the ground for creative and innovative thought. This dissertation is an examination of whether the Internet lived up to the expectations RSG had for it, and whether they were able to use their resources (in terms of their audience, their advertisers and the uniqueness of radio) to create something new and never seen before. The foremost aim of this dissertation is to shed some light onto the up-to-now under researched area of why radio stations have begun to develop on the Internet. Through the analysis of RSG, their comes to this subject some new thoughts and ideas about the convergence of these two mediums. RSG, and radio in general, are examined historically, practically and in comparison to the Internet. This is done in order to fully grasp the project that RSG had set for themselves and to realize where they had come from and where they hoped to go. It is argued that although RSG had hoped for great things, their innovative thought was not enough to guarantee them their dreams. They were not able to fully utilize the resources available to them in combination with what the Internet could offer them to fulfill the expectations they had for themselves. The foremost conclusion is that although RSG were able to envisage what the Internet could add to the radio station, they fell short of giving their listeners, users and advertisers a tool which could make the RSG website truly unique. Their website gives the user some interesting and useful applications, but it does not make full use of what the Internet and radio together could create.
- Full Text:
- Date Issued: 2002
- Authors: Vasques, Vanessa Claudia
- Date: 2002
- Subjects: Radio stations -- South Africa , Radio stations -- South Africa -- Marketing , Radio stations -- Computer network resources , Radiosondergrense
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3498 , http://hdl.handle.net/10962/d1003913 , Radio stations -- South Africa , Radio stations -- South Africa -- Marketing , Radio stations -- Computer network resources , Radiosondergrense
- Description: This thesis is a case study analysis of the dream one radio station had about creating something new and unique on the Internet. RadioSonderGrense (RSG), an Afrikaans South African radio station, saw opportunities for themselves as a radio station on the Internet and put enormous resources and man-power into their venture. Their vision of what the Internet could bring to their radio station, and what they could bring to a website set the ground for creative and innovative thought. This dissertation is an examination of whether the Internet lived up to the expectations RSG had for it, and whether they were able to use their resources (in terms of their audience, their advertisers and the uniqueness of radio) to create something new and never seen before. The foremost aim of this dissertation is to shed some light onto the up-to-now under researched area of why radio stations have begun to develop on the Internet. Through the analysis of RSG, their comes to this subject some new thoughts and ideas about the convergence of these two mediums. RSG, and radio in general, are examined historically, practically and in comparison to the Internet. This is done in order to fully grasp the project that RSG had set for themselves and to realize where they had come from and where they hoped to go. It is argued that although RSG had hoped for great things, their innovative thought was not enough to guarantee them their dreams. They were not able to fully utilize the resources available to them in combination with what the Internet could offer them to fulfill the expectations they had for themselves. The foremost conclusion is that although RSG were able to envisage what the Internet could add to the radio station, they fell short of giving their listeners, users and advertisers a tool which could make the RSG website truly unique. Their website gives the user some interesting and useful applications, but it does not make full use of what the Internet and radio together could create.
- Full Text:
- Date Issued: 2002
Counter-hair/gemonies: hair as a site of black identity struggle in post-apartheid South Africa
- Authors: Morey, Yvette Vivienne
- Date: 2002
- Subjects: Hairstyles -- South Africa , Women, Black -- Race identity , Hair -- Social aspects -- South Africa , Beauty, Personal -- Social aspects -- South Africa , Hairdressing of Black people
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3024 , http://hdl.handle.net/10962/d1002533 , Hairstyles -- South Africa , Women, Black -- Race identity , Hair -- Social aspects -- South Africa , Beauty, Personal -- Social aspects -- South Africa , Hairdressing of Black people
- Description: This thesis aims to allow the meanings engendered by various black hairstyle choices to emerge as discursive texts with which to further explore issues of black identity in post-apartheid South Africa. It seeks to identify what, if any, new discursive spaces and possibilities are operational in the post-apartheid capitalist context, and how identities are moulded by, and in tum, influence these possibilities. Operating within a discourse analytic approach, this research did not intend to establish fixed and generalisable notions of identity, but by unpacking the discursive baggage attached to historically loaded subjectivities it is concerned with reflecting identity as an ongoing and reflexive project. Entailing a diverse selection of texts, the analysis includes self-generated texts (stemming from interviews, a focus group and participant observation), and public domain texts (stemming from online and print media articles). Chapters 5 - 9 constitute the textual analysis. Using a consumer hair care product as a text, chapter 5 serves as an introduction to discourses surrounding black hair as a variously constructed object. This focus is concerned, more specifically, with the construction of black hair as a 'natural' object in chapter 6. Chapter 7 examines black hair gemonies and the " problematic classification and de/classification of class and consumer identities. Discourses pertaining to the construction and positioning of gendered and sexual subjectivities are explored in chapter 8. Finally, chapter 9 is concerned with the operations of discourses as they function to construct essentialised or hybrid conceptions of identity. The implications for black identity construction in post-apartheid South Africa are discussed in chapter 10 alongside a deconstruction of the research method and researcher positioning.
- Full Text:
- Date Issued: 2002
- Authors: Morey, Yvette Vivienne
- Date: 2002
- Subjects: Hairstyles -- South Africa , Women, Black -- Race identity , Hair -- Social aspects -- South Africa , Beauty, Personal -- Social aspects -- South Africa , Hairdressing of Black people
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3024 , http://hdl.handle.net/10962/d1002533 , Hairstyles -- South Africa , Women, Black -- Race identity , Hair -- Social aspects -- South Africa , Beauty, Personal -- Social aspects -- South Africa , Hairdressing of Black people
- Description: This thesis aims to allow the meanings engendered by various black hairstyle choices to emerge as discursive texts with which to further explore issues of black identity in post-apartheid South Africa. It seeks to identify what, if any, new discursive spaces and possibilities are operational in the post-apartheid capitalist context, and how identities are moulded by, and in tum, influence these possibilities. Operating within a discourse analytic approach, this research did not intend to establish fixed and generalisable notions of identity, but by unpacking the discursive baggage attached to historically loaded subjectivities it is concerned with reflecting identity as an ongoing and reflexive project. Entailing a diverse selection of texts, the analysis includes self-generated texts (stemming from interviews, a focus group and participant observation), and public domain texts (stemming from online and print media articles). Chapters 5 - 9 constitute the textual analysis. Using a consumer hair care product as a text, chapter 5 serves as an introduction to discourses surrounding black hair as a variously constructed object. This focus is concerned, more specifically, with the construction of black hair as a 'natural' object in chapter 6. Chapter 7 examines black hair gemonies and the " problematic classification and de/classification of class and consumer identities. Discourses pertaining to the construction and positioning of gendered and sexual subjectivities are explored in chapter 8. Finally, chapter 9 is concerned with the operations of discourses as they function to construct essentialised or hybrid conceptions of identity. The implications for black identity construction in post-apartheid South Africa are discussed in chapter 10 alongside a deconstruction of the research method and researcher positioning.
- Full Text:
- Date Issued: 2002
Design, evaluation and comparison of evolution and reinforcement learning models
- Authors: Mclean, Clinton Brett
- Date: 2002
- Subjects: Evolutionary computation Neural networks (Computer science) Reinforcement learning
- Language: English
- Type: Thesis , Masters , MEcon
- Identifier: vital:4625 , http://hdl.handle.net/10962/d1006493
- Description: This work presents the design, evaluation and comparison of evolution and reinforcement learning models, in isolation and combined in Darwinian and Lamarckian frameworks, with a particular emphasis being placed on their adaptive nature in response to environments that become increasingly unstable. Our ultimate objective is to determine whether hybrid models of evolution and learning can demonstrate adaptive qualities beyond those of such models when applied in isolation. This work demonstrates the limitations of evolution, reinforcement learning and Lamarckian models in dealing with increasingly unstable environments, while noting the effective adaptive nature of a Darwinian model to assimilate increasing levels of instability. This is shown to be a result of the Darwinian evolution model's ability to separate learning at two levels, the population's experience of the environment over the course of many generations and the individual's experience of the environment over the course of its lifetime. Thus, knowledge relating to the general characteristics of the environment over many generations can be maintained in the population's genotypes with phenotype (reinforcement) learning being utilized to adapt a particular agent to the particular characteristics of its environment. Lamarckian evolution, though, is shown to demonstrate adaptive characteristics that are highly effective in response to the stable environments. Selection and reproduction combined with reinforcement learning creates a model that has the ability to utilize useful knowledge produced by reinforcements, as opposed to random mutations, to accelerate the search process. As a result the influence of individual learning on the populations evolution is shown to be more successful when applied in the more direct Lamarckian form. Based on our results demonstrating the success of Lamarckian strategies in stable environments and Darwinian strategies in unstable environments, hybrid Darwinian/Lamarckian models are created with a view towards combining the advantages of both forms of evolution to produce a superior adaptive capability. Our investigation demonstrates that such hybrid models can effectively combine the adaptive advantageous of both Darwinian and Lamarckian evolution to provide a more effective capability of adapting to a range of conditions, from stable to unstable, appropriately adjusting the required degree of inheritance in response to the requirements of the environment.
- Full Text:
- Date Issued: 2002
- Authors: Mclean, Clinton Brett
- Date: 2002
- Subjects: Evolutionary computation Neural networks (Computer science) Reinforcement learning
- Language: English
- Type: Thesis , Masters , MEcon
- Identifier: vital:4625 , http://hdl.handle.net/10962/d1006493
- Description: This work presents the design, evaluation and comparison of evolution and reinforcement learning models, in isolation and combined in Darwinian and Lamarckian frameworks, with a particular emphasis being placed on their adaptive nature in response to environments that become increasingly unstable. Our ultimate objective is to determine whether hybrid models of evolution and learning can demonstrate adaptive qualities beyond those of such models when applied in isolation. This work demonstrates the limitations of evolution, reinforcement learning and Lamarckian models in dealing with increasingly unstable environments, while noting the effective adaptive nature of a Darwinian model to assimilate increasing levels of instability. This is shown to be a result of the Darwinian evolution model's ability to separate learning at two levels, the population's experience of the environment over the course of many generations and the individual's experience of the environment over the course of its lifetime. Thus, knowledge relating to the general characteristics of the environment over many generations can be maintained in the population's genotypes with phenotype (reinforcement) learning being utilized to adapt a particular agent to the particular characteristics of its environment. Lamarckian evolution, though, is shown to demonstrate adaptive characteristics that are highly effective in response to the stable environments. Selection and reproduction combined with reinforcement learning creates a model that has the ability to utilize useful knowledge produced by reinforcements, as opposed to random mutations, to accelerate the search process. As a result the influence of individual learning on the populations evolution is shown to be more successful when applied in the more direct Lamarckian form. Based on our results demonstrating the success of Lamarckian strategies in stable environments and Darwinian strategies in unstable environments, hybrid Darwinian/Lamarckian models are created with a view towards combining the advantages of both forms of evolution to produce a superior adaptive capability. Our investigation demonstrates that such hybrid models can effectively combine the adaptive advantageous of both Darwinian and Lamarckian evolution to provide a more effective capability of adapting to a range of conditions, from stable to unstable, appropriately adjusting the required degree of inheritance in response to the requirements of the environment.
- Full Text:
- Date Issued: 2002