Marine reservoir corrections : St. Helena, South Atlantic Ocean
- Lewis, Colin A, Reimer, P J, Reimer, R W
- Authors: Lewis, Colin A , Reimer, P J , Reimer, R W
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6701 , http://hdl.handle.net/10962/d1006737
- Description: We present the first marine reservoir age and ∆R determination for the island of St. Helena using marine mollusk radiocarbon dates obtained from an historical context of known age. This represents the first marine reservoir age and ∆R determination in the southern Atlantic Ocean within thousands of kilometers of the island. The depletion of 14C in the shells indicates a rather larger reservoir age for that portion of the surface Atlantic than models indicate. The implication is that upwelling old water along the Namibian coast is transported for a considerable distance, although it is likely to be variable on a decadal timescale. An artilleryman’s button, together with other artifacts found in a midden, demonstrate association of the mollusk shells with a narrow historic period of AD 1815–1835.
- Full Text:
- Date Issued: 2008
- Authors: Lewis, Colin A , Reimer, P J , Reimer, R W
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6701 , http://hdl.handle.net/10962/d1006737
- Description: We present the first marine reservoir age and ∆R determination for the island of St. Helena using marine mollusk radiocarbon dates obtained from an historical context of known age. This represents the first marine reservoir age and ∆R determination in the southern Atlantic Ocean within thousands of kilometers of the island. The depletion of 14C in the shells indicates a rather larger reservoir age for that portion of the surface Atlantic than models indicate. The implication is that upwelling old water along the Namibian coast is transported for a considerable distance, although it is likely to be variable on a decadal timescale. An artilleryman’s button, together with other artifacts found in a midden, demonstrate association of the mollusk shells with a narrow historic period of AD 1815–1835.
- Full Text:
- Date Issued: 2008
Media consumption and everyday life
- Authors: Strelitz, Larry N
- Date: 2008
- Language: English
- Type: text , Conference paper
- Identifier: vital:6324 , http://hdl.handle.net/10962/d1008550
- Description: I see this inaugural lecture as an opportunity to trace my journey into the field of media studies, showing how significant youthful experiences with the media set me off on my particular research trajectory. In this address I will use the umbrella term ‘mass media’ to cover both the traditional news media as well as forms of popular culture such as soap operas, popular music and so on. Sometimes we use the terms ‘popular culture’ and ‘mass media’ interchangeably as they both constitute the cultural life of ordinary people.
- Full Text:
- Date Issued: 2008
- Authors: Strelitz, Larry N
- Date: 2008
- Language: English
- Type: text , Conference paper
- Identifier: vital:6324 , http://hdl.handle.net/10962/d1008550
- Description: I see this inaugural lecture as an opportunity to trace my journey into the field of media studies, showing how significant youthful experiences with the media set me off on my particular research trajectory. In this address I will use the umbrella term ‘mass media’ to cover both the traditional news media as well as forms of popular culture such as soap operas, popular music and so on. Sometimes we use the terms ‘popular culture’ and ‘mass media’ interchangeably as they both constitute the cultural life of ordinary people.
- Full Text:
- Date Issued: 2008
Melanie Klein: a psychobiographical study
- Authors: Espinosa, Marianna J
- Date: 2008
- Subjects: Klein, Melanie Psychology -- Biographical methods Psychoanalysis
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2971 , http://hdl.handle.net/10962/d1002480
- Description: The objective of psychobiography is a better understanding of individuals, and psychobiographical case studies add meaning and value to research (Runyan, 1988a). Melanie Klein was chosen for this study through a purposive sampling method due to her contributions to the discipline of psychology, which placed her in a distinguished position regarding twentieth century psychoanalysis. Furthermore, no other psychobiography has been written on Klein. The primary aim of this study was to present the reader with a basic description of her life, and a secondary aim was to accomplish an in-depth description of Klein within her social and historical context. Due to these aims and the nature of psychobiography, it may be said that this is a qualitative study based on a single case method, described as explorative and descriptive. Data was analysed according to Huberman and Miles’ (1994) approach which consists of data reduction, display and verification. This study was guided by Levinson’s (1996) theory of Adult Development in Women. The theory allowed for an in-depth description of Klein’s experiences and social and historical contexts by merely illuminating her life. Finally, it may be said that this study contributed to the limited amount of psychobiographical research in South Africa.
- Full Text:
- Date Issued: 2008
- Authors: Espinosa, Marianna J
- Date: 2008
- Subjects: Klein, Melanie Psychology -- Biographical methods Psychoanalysis
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2971 , http://hdl.handle.net/10962/d1002480
- Description: The objective of psychobiography is a better understanding of individuals, and psychobiographical case studies add meaning and value to research (Runyan, 1988a). Melanie Klein was chosen for this study through a purposive sampling method due to her contributions to the discipline of psychology, which placed her in a distinguished position regarding twentieth century psychoanalysis. Furthermore, no other psychobiography has been written on Klein. The primary aim of this study was to present the reader with a basic description of her life, and a secondary aim was to accomplish an in-depth description of Klein within her social and historical context. Due to these aims and the nature of psychobiography, it may be said that this is a qualitative study based on a single case method, described as explorative and descriptive. Data was analysed according to Huberman and Miles’ (1994) approach which consists of data reduction, display and verification. This study was guided by Levinson’s (1996) theory of Adult Development in Women. The theory allowed for an in-depth description of Klein’s experiences and social and historical contexts by merely illuminating her life. Finally, it may be said that this study contributed to the limited amount of psychobiographical research in South Africa.
- Full Text:
- Date Issued: 2008
Melatonin and anticancer therapy interactions with 5-Fluorouracil
- Authors: Cassim, Layla
- Date: 2008
- Subjects: Melatonin Melatonin -- Therapeutic use Antineoplastic agents Fluorouracil Fluorouracil -- Toxicology Cancer -- Treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3746 , http://hdl.handle.net/10962/d1003224
- Description: On the basis of clinical studies, some researchers have advocated that the neurohormone and antioxidant melatonin, shown to possess intrinsic anticancer properties, be used as co-therapy in cancer patients being treated with the antineoplastic agent 5-fluorouracil, as increased patient survival times and enhanced quality of life have been observed. The focus of this research was thus to investigate the mechanisms of this seemingly beneficial drug interaction between 5-fluorouracil and melatonin. Metabolism studies were undertaken, in which it was established that there is no hepatic metabolic drug interaction between these agents by cytochrome P450, and that neither agent alters the activity of this enzyme system. Co-therapy with melatonin is thus unlikely to alter plasma levels of 5-fluorouracil by this mechanism. Novel mechanisms by which 5-fluorouracil is toxic were elucidated, such as the induction of lipid peroxidation, due to the formation of reactive oxygen species; decreases in brain serotonin, dopamine and norepinephrine levels, possibly leading to depression; hippocampal shrinkage and morphological alterations and lysis of hippocampal cells, which may underlie cognitive impairment; and a reduction in the nociceptive threshold when administered acutely. All these deleterious effects are attenuated by the co-administration of melatonin, suggesting that the agent exhibits antidepressive and analgesic properties, in addition to its known antioxidative and free radical-scavenging abilities. This suggests that melatonin cotherapy can significantly decrease 5-fluorouracil-induced toxicity, but this may also exert a protective effect on cancer cells and thus compromise the anticancer efficacy of 5-fluorouracil. It was, furthermore, found that stimulation of indoleamine 2,3-dioxygenase activity, mediated by increases in superoxide anion and interferon-γ levels, may underlie resistance to 5-fluorouracil therapy. Melatonin was shown to increase superoxide anion levels in vivo, and this is believed to be by conversion to the metabolite and known oxidant 6- hydroxymelatonin. This highlights that the possible deleterious effects of melatonin metabolites should be studied further. Serum corticosterone levels and cytokine profiles are unaltered by both 5-FU and melatonin, suggesting that these agents may be used by HIV infected individuals without promoting the progression to AIDS. It can thus be concluded that melatonin co-therapy is potentially useful in countering 5-fluorouracil toxicity.
- Full Text:
- Date Issued: 2008
- Authors: Cassim, Layla
- Date: 2008
- Subjects: Melatonin Melatonin -- Therapeutic use Antineoplastic agents Fluorouracil Fluorouracil -- Toxicology Cancer -- Treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3746 , http://hdl.handle.net/10962/d1003224
- Description: On the basis of clinical studies, some researchers have advocated that the neurohormone and antioxidant melatonin, shown to possess intrinsic anticancer properties, be used as co-therapy in cancer patients being treated with the antineoplastic agent 5-fluorouracil, as increased patient survival times and enhanced quality of life have been observed. The focus of this research was thus to investigate the mechanisms of this seemingly beneficial drug interaction between 5-fluorouracil and melatonin. Metabolism studies were undertaken, in which it was established that there is no hepatic metabolic drug interaction between these agents by cytochrome P450, and that neither agent alters the activity of this enzyme system. Co-therapy with melatonin is thus unlikely to alter plasma levels of 5-fluorouracil by this mechanism. Novel mechanisms by which 5-fluorouracil is toxic were elucidated, such as the induction of lipid peroxidation, due to the formation of reactive oxygen species; decreases in brain serotonin, dopamine and norepinephrine levels, possibly leading to depression; hippocampal shrinkage and morphological alterations and lysis of hippocampal cells, which may underlie cognitive impairment; and a reduction in the nociceptive threshold when administered acutely. All these deleterious effects are attenuated by the co-administration of melatonin, suggesting that the agent exhibits antidepressive and analgesic properties, in addition to its known antioxidative and free radical-scavenging abilities. This suggests that melatonin cotherapy can significantly decrease 5-fluorouracil-induced toxicity, but this may also exert a protective effect on cancer cells and thus compromise the anticancer efficacy of 5-fluorouracil. It was, furthermore, found that stimulation of indoleamine 2,3-dioxygenase activity, mediated by increases in superoxide anion and interferon-γ levels, may underlie resistance to 5-fluorouracil therapy. Melatonin was shown to increase superoxide anion levels in vivo, and this is believed to be by conversion to the metabolite and known oxidant 6- hydroxymelatonin. This highlights that the possible deleterious effects of melatonin metabolites should be studied further. Serum corticosterone levels and cytokine profiles are unaltered by both 5-FU and melatonin, suggesting that these agents may be used by HIV infected individuals without promoting the progression to AIDS. It can thus be concluded that melatonin co-therapy is potentially useful in countering 5-fluorouracil toxicity.
- Full Text:
- Date Issued: 2008
Microfinance sustainability versus development objectives: an assessment of the South African environment
- Authors: Hoskinson, Brenda
- Date: 2008
- Subjects: Microfinance -- South Africa South Africa -- Economic conditions -- 1991- Poor -- Finance, Personal Microfinance -- South Africa Case studies
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2782 , http://hdl.handle.net/10962/d1002992
- Description: In a world where almost half of the population lives in poverty, the alleviation of poverty is a serious developmental challenge for many states. Microfinance has grown in popularity as a means for achieving poverty reduction all over the world. Due to the success of microfinance institutions, such as the Grameen Bank, in achieving self-sufficiency and improving the lives of its clients, the expectations for similar institutions are high. MFIs attempt to find a balance between business and development goals. It is not necessarily a contradiction to be a business seeking profit as well as being an institution committed to development. However, the values coupled with these two objectives are sometimes conflicting. Thus it is important to see how equilibrium can be achieved and to note what sacrifices must be made in order to reach a balance. This thesis will focus on examining and assessing the challenges faced by South African MFIs in balancing development goals while at the same time having to be self-sufficient. The Small Enterprise Foundation will be used as a case study to consider the particular experiences of a South African MFI. The evaluation of the unique challenges that the South African landscape presents will provide a context in which to understand microfinance operations and a clearer understanding of the particular problems and challenges faced by the South African micro-finance industry in balancing the achievement of development goals against the imperative to be self sustainable in providing services to the poor. Through that understanding the common conception of what makes a “successful” MFI will also be challenged.
- Full Text:
- Date Issued: 2008
- Authors: Hoskinson, Brenda
- Date: 2008
- Subjects: Microfinance -- South Africa South Africa -- Economic conditions -- 1991- Poor -- Finance, Personal Microfinance -- South Africa Case studies
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2782 , http://hdl.handle.net/10962/d1002992
- Description: In a world where almost half of the population lives in poverty, the alleviation of poverty is a serious developmental challenge for many states. Microfinance has grown in popularity as a means for achieving poverty reduction all over the world. Due to the success of microfinance institutions, such as the Grameen Bank, in achieving self-sufficiency and improving the lives of its clients, the expectations for similar institutions are high. MFIs attempt to find a balance between business and development goals. It is not necessarily a contradiction to be a business seeking profit as well as being an institution committed to development. However, the values coupled with these two objectives are sometimes conflicting. Thus it is important to see how equilibrium can be achieved and to note what sacrifices must be made in order to reach a balance. This thesis will focus on examining and assessing the challenges faced by South African MFIs in balancing development goals while at the same time having to be self-sufficient. The Small Enterprise Foundation will be used as a case study to consider the particular experiences of a South African MFI. The evaluation of the unique challenges that the South African landscape presents will provide a context in which to understand microfinance operations and a clearer understanding of the particular problems and challenges faced by the South African micro-finance industry in balancing the achievement of development goals against the imperative to be self sustainable in providing services to the poor. Through that understanding the common conception of what makes a “successful” MFI will also be challenged.
- Full Text:
- Date Issued: 2008
Mimics and magnets : The importance of color and ecological facilitation in floral deception
- Peter, Craig I, Johnson, Steven D
- Authors: Peter, Craig I , Johnson, Steven D
- Date: 2008
- Identifier: vital:6536 , http://hdl.handle.net/10962/d1005977
- Description: Plants that lack floral rewards can attract pollinators if they share attractive floral signals with rewarding plants. These deceptive plants should benefit from flowering in close proximity to such rewarding plants, because pollinators are locally conditioned on floral signals of the rewarding plants (mimic effect) and because pollinators are more abundant close to rewarding plants (magnet effect). We tested these ideas using the non-rewarding South African plant Eulophia zeyheriana (Orchidaceae) as a study system. Field observations revealed that E. zeyheriana is pollinated solely by solitary bees belonging to a single species of Lipotriches (Halictidae) that appears to be closely associated with the flowers of Wahlenbergia cuspidata (Campanulaceae), a rewarding plant with which the orchid is often sympatric. The pale blue color of the flowers of E. zeyheriana differs strongly from flowers of its congeners, but is very similar to that of flowers of W. cuspidata. Analysis of spectral reflectance patterns using a bee vision model showed that bees are unlikely to be able to distinguish the two species in terms of flower color. A UV-absorbing sunscreen was applied to the flowers of the orchid in order to alter their color, and this resulted in a significant decline in pollinator visits, thus indicating the importance of flower color for attraction of Lipotriches bees. Pollination success in the orchid was strongly affected by proximity to patches of W. cuspidata. This was evident from one of two surveys of natural populations of the orchid, as well as experiments in which we translocated inflorescences of the orchid either into patches of W. cuspidata or 40 m outside such patches. Flower color and location of E. zeyheriana plants relative to rewarding magnet patches are therefore key components of the exploitation by this orchid of the relationship between W. cuspidata and Lipotriches bee pollinators.
- Full Text:
- Date Issued: 2008
- Authors: Peter, Craig I , Johnson, Steven D
- Date: 2008
- Identifier: vital:6536 , http://hdl.handle.net/10962/d1005977
- Description: Plants that lack floral rewards can attract pollinators if they share attractive floral signals with rewarding plants. These deceptive plants should benefit from flowering in close proximity to such rewarding plants, because pollinators are locally conditioned on floral signals of the rewarding plants (mimic effect) and because pollinators are more abundant close to rewarding plants (magnet effect). We tested these ideas using the non-rewarding South African plant Eulophia zeyheriana (Orchidaceae) as a study system. Field observations revealed that E. zeyheriana is pollinated solely by solitary bees belonging to a single species of Lipotriches (Halictidae) that appears to be closely associated with the flowers of Wahlenbergia cuspidata (Campanulaceae), a rewarding plant with which the orchid is often sympatric. The pale blue color of the flowers of E. zeyheriana differs strongly from flowers of its congeners, but is very similar to that of flowers of W. cuspidata. Analysis of spectral reflectance patterns using a bee vision model showed that bees are unlikely to be able to distinguish the two species in terms of flower color. A UV-absorbing sunscreen was applied to the flowers of the orchid in order to alter their color, and this resulted in a significant decline in pollinator visits, thus indicating the importance of flower color for attraction of Lipotriches bees. Pollination success in the orchid was strongly affected by proximity to patches of W. cuspidata. This was evident from one of two surveys of natural populations of the orchid, as well as experiments in which we translocated inflorescences of the orchid either into patches of W. cuspidata or 40 m outside such patches. Flower color and location of E. zeyheriana plants relative to rewarding magnet patches are therefore key components of the exploitation by this orchid of the relationship between W. cuspidata and Lipotriches bee pollinators.
- Full Text:
- Date Issued: 2008
Mitigating risk through effective information technology operations in local governments : towards a best practice
- Authors: Kaselowski, Emile
- Date: 2008
- Subjects: Information technology -- South Africa , Local government -- South Africa -- Data processing
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9779 , http://hdl.handle.net/10948/776 , Information technology -- South Africa , Local government -- South Africa -- Data processing
- Description: Sound IT governance is becoming increasingly important for any public or private organisation. However, based on previous research, it can be argued that local municipalities in South Africa are seemingly struggling to implement sound IT governance practices. As a result, very few municipalities perform strategic IT planning and as many as 80percent of municipalities do not have a Master System Plan (MSP) in place, which is required by law. IT governance and corporate governance are lately viewed as one and no longer as two separate governance disciplines, because computer systems and electronic communication are more important now than ever for the survival of any organisation. Therefore, it is important for municipalities to streamline their efforts towards sound IT governance. There are limitations which are faced by municipalities that limit these efforts. Possibly the biggest contributing factor towards this current municipal IT governance predicament, among others, is the fact that there are very few, if any, guidelines and resources available to municipalities to aid them in implementing proper IT infrastructures, systems and governance procedures. To improve the current state of IT governance in municipalities, better guidelines and procedures are required. This dissertation presents an IT governance framework to meet this aforementioned requirement. It is tailored to the requirements of local municipalities and is based on the international best practice, the Control Objectives for Information and related Technologies (COBIT) and the ISO/IEC 17799 code of practice for information security management. This proposed framework takes into account the Municipal Systems Act (nr 32 of 2000), Municipal Structures Act (nr 117 of 1998) and annual municipal IT audit reports’ requirements. Research was conducted at a district and its underlying, local municipalities to determine the proper IT governance criteria for municipalities. Case studies were performed at the municipalities and consisted of performing literature studies on the available municipal legislation and annual, municipal IT audit reports, conducting COBIT gap analyses, an ISO 17799 analysis, conducting interviews and developing questionnaires and data capturing and presentation tools. The resultant, proposed IT governance framework, titled the IT strategic objective plan (IT-SOP), when implemented by a municipality, should provide a solid governance foundation on which to base its business processes on.
- Full Text:
- Date Issued: 2008
- Authors: Kaselowski, Emile
- Date: 2008
- Subjects: Information technology -- South Africa , Local government -- South Africa -- Data processing
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9779 , http://hdl.handle.net/10948/776 , Information technology -- South Africa , Local government -- South Africa -- Data processing
- Description: Sound IT governance is becoming increasingly important for any public or private organisation. However, based on previous research, it can be argued that local municipalities in South Africa are seemingly struggling to implement sound IT governance practices. As a result, very few municipalities perform strategic IT planning and as many as 80percent of municipalities do not have a Master System Plan (MSP) in place, which is required by law. IT governance and corporate governance are lately viewed as one and no longer as two separate governance disciplines, because computer systems and electronic communication are more important now than ever for the survival of any organisation. Therefore, it is important for municipalities to streamline their efforts towards sound IT governance. There are limitations which are faced by municipalities that limit these efforts. Possibly the biggest contributing factor towards this current municipal IT governance predicament, among others, is the fact that there are very few, if any, guidelines and resources available to municipalities to aid them in implementing proper IT infrastructures, systems and governance procedures. To improve the current state of IT governance in municipalities, better guidelines and procedures are required. This dissertation presents an IT governance framework to meet this aforementioned requirement. It is tailored to the requirements of local municipalities and is based on the international best practice, the Control Objectives for Information and related Technologies (COBIT) and the ISO/IEC 17799 code of practice for information security management. This proposed framework takes into account the Municipal Systems Act (nr 32 of 2000), Municipal Structures Act (nr 117 of 1998) and annual municipal IT audit reports’ requirements. Research was conducted at a district and its underlying, local municipalities to determine the proper IT governance criteria for municipalities. Case studies were performed at the municipalities and consisted of performing literature studies on the available municipal legislation and annual, municipal IT audit reports, conducting COBIT gap analyses, an ISO 17799 analysis, conducting interviews and developing questionnaires and data capturing and presentation tools. The resultant, proposed IT governance framework, titled the IT strategic objective plan (IT-SOP), when implemented by a municipality, should provide a solid governance foundation on which to base its business processes on.
- Full Text:
- Date Issued: 2008
Model selection for cointegrated relationships in small samples
- He, Wei
- Authors: He, Wei
- Date: 2008
- Subjects: Economics -- Statistical methods , Cointegration -- South Africa , Econometrics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10570 , http://hdl.handle.net/10948/971 , Economics -- Statistical methods , Cointegration -- South Africa , Econometrics
- Description: Vector autoregression models have become widely used research tools in the analysis of macroeconomic time series. Cointegrated techniques are an essential part of empirical macroeconomic research. They infer causal long-run relationships between nonstationary variables. In this study, six information criteria were reviewed and compared. The methods focused on determining the optimum information criteria for detecting the correct lag structure of a two-variable cointegrated process.
- Full Text:
- Date Issued: 2008
- Authors: He, Wei
- Date: 2008
- Subjects: Economics -- Statistical methods , Cointegration -- South Africa , Econometrics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10570 , http://hdl.handle.net/10948/971 , Economics -- Statistical methods , Cointegration -- South Africa , Econometrics
- Description: Vector autoregression models have become widely used research tools in the analysis of macroeconomic time series. Cointegrated techniques are an essential part of empirical macroeconomic research. They infer causal long-run relationships between nonstationary variables. In this study, six information criteria were reviewed and compared. The methods focused on determining the optimum information criteria for detecting the correct lag structure of a two-variable cointegrated process.
- Full Text:
- Date Issued: 2008
Molecular characterization of the Hsp70/Hsp90 organizing protein (Hop) phosphorylation, subcellular localization and interaction with Hsp90
- Authors: Daniel, Sheril
- Date: 2008
- Subjects: Molecular chaperones Phosphorylation Proteins Heat shock proteins Surface plasmon resonance Cytosol
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3996 , http://hdl.handle.net/10962/d1004056
- Description: Hop (Hsp70-Hsp90 Organizing Protein) is a co-chaperone of two major molecular chaperones, Hsp70 and Hsp90, and acts by transferring substrates from Hsp70 to Hsp90. Although under normal conditions Hop is predominantly localized within the cytosol, Hop has been detected in the nucleus under certain conditions including cell cycle arrest. A putative nuclear localization signal (NLS) has been identified within Hop, which overlaps with the TPR2A domain (previously shown to be critical for Hop-Hsp90 interactions). Hop is phosphorylated in vitro by two cell cycle kinases, namely, casein kinase II (CKII) at S189 and cdc2-kinase at T198; both residues are found upstream of the putative NLS and TPR2A domain. Mimicking phosphorylation at either phosphorylation site appeared to affect the subcellular localization of Hop. The aim of this study was to characterize Hop with respect to its phosphorylation status in vivo, as well as its subcellular localization pattern under heat stress and determine how these properties affected its interaction with Hsp90 as a co-chaperone. Dephosphorylation of proteins under normal and heat shock conditions changed the isoform composition of Hop, providing strong evidence that Hop was phosphorylated in vivo. Surface plasmon resonance (SPR) and glutatione-S-transferase (GST) co-precipitation studies showed that a cdc2-kinase phosphorylated mimic of Hop disrupted Hop-Hsp90 binding. A full length Hop-EGFP construct, as well as substitution mutants of the predicted NLS residues within the Hop-EGFP construct, were transfected into baby hamster kidney (BHK)-21 cells in order to establish the subcellular localization of Hop under heat stress and to test whether predicted residues were critical for nuclear localization of Hop. Under normal conditions, both Hop-EGFP and the NLS mutants were predominantly cytosolic, but when the cells were subjected to heat stress, Hop and its NLS-mutants were localized to both the cytosol and the nucleus. SPR and GST co-precipitation studies showed that substitution of the residues within the major arm of the putative NLS abrogated Hop-Hsp90 interactions. The data obtained from this study, showed for the first time, that Hop was phosphorylated in vivo and suggested that phosphorylation of Hop by cdc2-kinase could inhibit Hop-Hsp90 interactions. Moreover, these results suggested that the subcellular localization of Hop was dependent on stress levels of the cell, particularly heat stress. We propose that the nuclear localization of Hop may be primarily regulated by stress and secondarily by cell cycle arrest. The major arm of the putative NLS did not affect the localization of Hop directly, but was shown to be critical for Hop-Hsp90 binding in vitro. The results of this study suggested that binding of Hop to Hsp90 sequestered Hop within the cytosol and that Hsp90 acted as a cytosolic retention factor for Hop. Both phosphorylation of Hop, and its subcellular localization, appeared to be intimately related to its interaction with Hsp90 as a co-chaperone.
- Full Text:
- Date Issued: 2008
- Authors: Daniel, Sheril
- Date: 2008
- Subjects: Molecular chaperones Phosphorylation Proteins Heat shock proteins Surface plasmon resonance Cytosol
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3996 , http://hdl.handle.net/10962/d1004056
- Description: Hop (Hsp70-Hsp90 Organizing Protein) is a co-chaperone of two major molecular chaperones, Hsp70 and Hsp90, and acts by transferring substrates from Hsp70 to Hsp90. Although under normal conditions Hop is predominantly localized within the cytosol, Hop has been detected in the nucleus under certain conditions including cell cycle arrest. A putative nuclear localization signal (NLS) has been identified within Hop, which overlaps with the TPR2A domain (previously shown to be critical for Hop-Hsp90 interactions). Hop is phosphorylated in vitro by two cell cycle kinases, namely, casein kinase II (CKII) at S189 and cdc2-kinase at T198; both residues are found upstream of the putative NLS and TPR2A domain. Mimicking phosphorylation at either phosphorylation site appeared to affect the subcellular localization of Hop. The aim of this study was to characterize Hop with respect to its phosphorylation status in vivo, as well as its subcellular localization pattern under heat stress and determine how these properties affected its interaction with Hsp90 as a co-chaperone. Dephosphorylation of proteins under normal and heat shock conditions changed the isoform composition of Hop, providing strong evidence that Hop was phosphorylated in vivo. Surface plasmon resonance (SPR) and glutatione-S-transferase (GST) co-precipitation studies showed that a cdc2-kinase phosphorylated mimic of Hop disrupted Hop-Hsp90 binding. A full length Hop-EGFP construct, as well as substitution mutants of the predicted NLS residues within the Hop-EGFP construct, were transfected into baby hamster kidney (BHK)-21 cells in order to establish the subcellular localization of Hop under heat stress and to test whether predicted residues were critical for nuclear localization of Hop. Under normal conditions, both Hop-EGFP and the NLS mutants were predominantly cytosolic, but when the cells were subjected to heat stress, Hop and its NLS-mutants were localized to both the cytosol and the nucleus. SPR and GST co-precipitation studies showed that substitution of the residues within the major arm of the putative NLS abrogated Hop-Hsp90 interactions. The data obtained from this study, showed for the first time, that Hop was phosphorylated in vivo and suggested that phosphorylation of Hop by cdc2-kinase could inhibit Hop-Hsp90 interactions. Moreover, these results suggested that the subcellular localization of Hop was dependent on stress levels of the cell, particularly heat stress. We propose that the nuclear localization of Hop may be primarily regulated by stress and secondarily by cell cycle arrest. The major arm of the putative NLS did not affect the localization of Hop directly, but was shown to be critical for Hop-Hsp90 binding in vitro. The results of this study suggested that binding of Hop to Hsp90 sequestered Hop within the cytosol and that Hsp90 acted as a cytosolic retention factor for Hop. Both phosphorylation of Hop, and its subcellular localization, appeared to be intimately related to its interaction with Hsp90 as a co-chaperone.
- Full Text:
- Date Issued: 2008
Monitoring population trends of introduced rusa deer (Cervus timorensis russa) in New Caledonian sclerophyll forests : tests and relevance of methods for management programmes
- Authors: Roques-Rogery, Guillaume
- Date: 2008
- Subjects: Cervus timorensis -- Caledon , Deer -- Management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10750 , http://hdl.handle.net/10948/727 , Cervus timorensis -- Caledon , Deer -- Management
- Description: New Caledonia, an archipelago situated in the South-West Pacific Ocean has a very high biodiversity of which many flora and fauna species are endemic, and is therefore considered as one of the world hotspots for the biodiversity conservation. Sclerophyll forests, one of the five main vegetation types occurring on the island are mainly threatened by anthropogenic activities. Rusa deer (Cervus timorensis russa) were introduced into New Caledonia from Java in 1870. They have colonised all the biotopes of the main island, and represent one of the major threats to the New Caledonian sclerophyll forests. Currently, there is a lack of management tools to monitor the trends of rusa deer in New Caledonian sclerophyll forests. To test monitoring methods for use as management tools, six sclerophyll forests study sites were studied using direct census methods (i.e. spotlight count and drive count), indirect census methods (i.e. faecal standing crop method) and three indices (i.e. the faecal pellet groups index, the browsing index and the antler rubbing index). The faecal pellet groups index is based on sampling pellet groups in plots along transects. To ensure reliable data collection with a coefficient of variation of the mean number of intact faecal pellet groups per plot per transect of less than 20 percent, my study indicated that 15 plots per transect and 20 transects per sites should be sampled in New Caledonian sclerophyll forests whereas previous studies conducted in New Zealand indicated that a minimum of 25 plots per transect and of 18 transects per site should be sampled. The advantages of reducing the number of plots per transect and of transects per site is that it reduces the expenses (e.g. time, finance) and the bias due to data collection (e.g. fatigue, boredom and visual activity) which will improve the precision of the data recorded. Estimates of rusa deer density obtained from the census methods were not correlated (r = - 0.425, df = 4, P = 0.401) due to my small sample size. The reliability of these estimates is questionable because of biases. Previous publications have shown that biases are difficult to avoid when using direct census methods and that it is difficult to estimate the size of animal populations with accuracy and precision. The faecal standing crop method was subjected to bias because the estimation of the decay rate and the defecation rate were unreliable. These methods were not recommended for rusa deer management in New Caledonian sclerophyll forests. Of the three indices tested, the faecal pellet groups index and the browsing index based on unpalatable browse species were the most reliable as the confidence intervals of these two indices were small (i.e. from ±0.08 to ±0.11 for the faecal pellet groups index; from ±0.04 to ±0.27 for the browsing index of unpalatable browse species), and they also showed significant correlations with a subjective ranking of the rusa deer density based on expert knowledge (rs = 0.829, df = 4, P = 0.042 and rs = 0.829, df = 4, P = 0.042 respectively). These two indices appear to show the most promise for use as management tools, as they could reliably track local variations of rusa deer densities on the sclerophyll forests. These two indices could be used by wildlife technicians in New Caledonia to establish management plans of rusa deer populations which rely on participative management involving the stakeholders (e.g. hunters, forest managers, local communities). We believe that the faecal pellet groups index and the browsing index could be useful to monitor rusa deer populations in New Caledonian sclerophyll forests, and meet conservation and hunting objectives of the local population and authorities. Management tools such as culling and hunting operations will be implemented in New Caledonian sclerophyll forests where monitoring of indices I recommended show an increase in the deer population. Stakeholders will be involved in the implementation of the monitoring tools (i.e. indices) and of the management tools (e.g. culling and hunting operations, fencing) but also in decision making for the management of the rusa deer in New Caledonian sclerophyll forests.
- Full Text:
- Date Issued: 2008
- Authors: Roques-Rogery, Guillaume
- Date: 2008
- Subjects: Cervus timorensis -- Caledon , Deer -- Management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10750 , http://hdl.handle.net/10948/727 , Cervus timorensis -- Caledon , Deer -- Management
- Description: New Caledonia, an archipelago situated in the South-West Pacific Ocean has a very high biodiversity of which many flora and fauna species are endemic, and is therefore considered as one of the world hotspots for the biodiversity conservation. Sclerophyll forests, one of the five main vegetation types occurring on the island are mainly threatened by anthropogenic activities. Rusa deer (Cervus timorensis russa) were introduced into New Caledonia from Java in 1870. They have colonised all the biotopes of the main island, and represent one of the major threats to the New Caledonian sclerophyll forests. Currently, there is a lack of management tools to monitor the trends of rusa deer in New Caledonian sclerophyll forests. To test monitoring methods for use as management tools, six sclerophyll forests study sites were studied using direct census methods (i.e. spotlight count and drive count), indirect census methods (i.e. faecal standing crop method) and three indices (i.e. the faecal pellet groups index, the browsing index and the antler rubbing index). The faecal pellet groups index is based on sampling pellet groups in plots along transects. To ensure reliable data collection with a coefficient of variation of the mean number of intact faecal pellet groups per plot per transect of less than 20 percent, my study indicated that 15 plots per transect and 20 transects per sites should be sampled in New Caledonian sclerophyll forests whereas previous studies conducted in New Zealand indicated that a minimum of 25 plots per transect and of 18 transects per site should be sampled. The advantages of reducing the number of plots per transect and of transects per site is that it reduces the expenses (e.g. time, finance) and the bias due to data collection (e.g. fatigue, boredom and visual activity) which will improve the precision of the data recorded. Estimates of rusa deer density obtained from the census methods were not correlated (r = - 0.425, df = 4, P = 0.401) due to my small sample size. The reliability of these estimates is questionable because of biases. Previous publications have shown that biases are difficult to avoid when using direct census methods and that it is difficult to estimate the size of animal populations with accuracy and precision. The faecal standing crop method was subjected to bias because the estimation of the decay rate and the defecation rate were unreliable. These methods were not recommended for rusa deer management in New Caledonian sclerophyll forests. Of the three indices tested, the faecal pellet groups index and the browsing index based on unpalatable browse species were the most reliable as the confidence intervals of these two indices were small (i.e. from ±0.08 to ±0.11 for the faecal pellet groups index; from ±0.04 to ±0.27 for the browsing index of unpalatable browse species), and they also showed significant correlations with a subjective ranking of the rusa deer density based on expert knowledge (rs = 0.829, df = 4, P = 0.042 and rs = 0.829, df = 4, P = 0.042 respectively). These two indices appear to show the most promise for use as management tools, as they could reliably track local variations of rusa deer densities on the sclerophyll forests. These two indices could be used by wildlife technicians in New Caledonia to establish management plans of rusa deer populations which rely on participative management involving the stakeholders (e.g. hunters, forest managers, local communities). We believe that the faecal pellet groups index and the browsing index could be useful to monitor rusa deer populations in New Caledonian sclerophyll forests, and meet conservation and hunting objectives of the local population and authorities. Management tools such as culling and hunting operations will be implemented in New Caledonian sclerophyll forests where monitoring of indices I recommended show an increase in the deer population. Stakeholders will be involved in the implementation of the monitoring tools (i.e. indices) and of the management tools (e.g. culling and hunting operations, fencing) but also in decision making for the management of the rusa deer in New Caledonian sclerophyll forests.
- Full Text:
- Date Issued: 2008
Mussolini's moment: Roy Sargeant directs The Merchant of Venice at Maynardville, January, 2007
- Authors: Wright, Laurence
- Date: 2008
- Language: English
- Type: text , article
- Identifier: vital:7047 , http://hdl.handle.net/10962/d1007389 , http://hdl.handle.net/10520/EJC48107
- Description: preprint , What an inspired choice of play for this year’s Maynardville offering! With the national scene strewn with trials and rumours of trials, all of them vital to the quality of life citizens of this fair city beneath the beautiful mountain (‘Belmont’) may hope to enjoy in the future, Shakespeare’s cliff-hanger about the use and abuse of the law couldn’t be more apt.
- Full Text:
- Date Issued: 2008
- Authors: Wright, Laurence
- Date: 2008
- Language: English
- Type: text , article
- Identifier: vital:7047 , http://hdl.handle.net/10962/d1007389 , http://hdl.handle.net/10520/EJC48107
- Description: preprint , What an inspired choice of play for this year’s Maynardville offering! With the national scene strewn with trials and rumours of trials, all of them vital to the quality of life citizens of this fair city beneath the beautiful mountain (‘Belmont’) may hope to enjoy in the future, Shakespeare’s cliff-hanger about the use and abuse of the law couldn’t be more apt.
- Full Text:
- Date Issued: 2008
Namibian school principals' perceptions of their management needs
- Authors: Kapapero, Fanuel
- Date: 2008
- Subjects: School principals -- Self-rating of -- Namibia School principals -- Rating of -- Namibia School principals -- Management -- Namibia School principals -- Development -- Namibia School management and organization -- Namibia Educational leadership -- Namibia School supervision -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1674 , http://hdl.handle.net/10962/d1003557
- Description: The Namibian education system is at the crossroads as a result of the demands of the Education and Training Sector Improvement Programme (ETSIP), a programme initiated by the Government to address shortcomings in the education and training sector. ETSIP requires that school principals play a much more significant role to realize the goal of quality education, which is one of the major goals of education reform. In view of the ever-increasing responsibilities of the principals for ensuring the quality of education, the need for management development has become more apparent. Although management development for principals in the African context is a recent phenomenon, it has been a subject of extensive research over the years in many developed countries. The findings of these studies suggest that it has the potential to improve the quality of school leadership and ultimately lead to school improvement. In Namibia, literature suggests that little has been done to determine the needs of school principals with regards to their management development. This study therefore seeks to address that need. The study is situated in the interpretive research paradigm whose central purpose is to interpret and understand the phenomenon through the perceptions and experience of the participants. Data were collected by means of semi-structured interviews and document analysis. The findings generally suggest that principals perceive management development as vehicle to empowerment and capacity building. The findings further suggest that principals would prefer management programmes that are more experienced-based and offer opportunities for reflection. The findings also brought to light the aspect of monitoring and support as a critical element in the success of management development programmes. As far as the management development needs of school principals are concerned, the findings highlighted the following needs: the need to be trained on how to manage change which include the new curriculum and policies, training in information communication and technology and training in the management of human and financial resources which include instructional leadership and budgeting.
- Full Text:
- Date Issued: 2008
- Authors: Kapapero, Fanuel
- Date: 2008
- Subjects: School principals -- Self-rating of -- Namibia School principals -- Rating of -- Namibia School principals -- Management -- Namibia School principals -- Development -- Namibia School management and organization -- Namibia Educational leadership -- Namibia School supervision -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1674 , http://hdl.handle.net/10962/d1003557
- Description: The Namibian education system is at the crossroads as a result of the demands of the Education and Training Sector Improvement Programme (ETSIP), a programme initiated by the Government to address shortcomings in the education and training sector. ETSIP requires that school principals play a much more significant role to realize the goal of quality education, which is one of the major goals of education reform. In view of the ever-increasing responsibilities of the principals for ensuring the quality of education, the need for management development has become more apparent. Although management development for principals in the African context is a recent phenomenon, it has been a subject of extensive research over the years in many developed countries. The findings of these studies suggest that it has the potential to improve the quality of school leadership and ultimately lead to school improvement. In Namibia, literature suggests that little has been done to determine the needs of school principals with regards to their management development. This study therefore seeks to address that need. The study is situated in the interpretive research paradigm whose central purpose is to interpret and understand the phenomenon through the perceptions and experience of the participants. Data were collected by means of semi-structured interviews and document analysis. The findings generally suggest that principals perceive management development as vehicle to empowerment and capacity building. The findings further suggest that principals would prefer management programmes that are more experienced-based and offer opportunities for reflection. The findings also brought to light the aspect of monitoring and support as a critical element in the success of management development programmes. As far as the management development needs of school principals are concerned, the findings highlighted the following needs: the need to be trained on how to manage change which include the new curriculum and policies, training in information communication and technology and training in the management of human and financial resources which include instructional leadership and budgeting.
- Full Text:
- Date Issued: 2008
Natural resource harvesting and disturbance in communal lands: assessing the roles of local ecological knowledge, dependency and market access
- Authors: Steele, Melita Zoë
- Date: 2008
- Subjects: Non-timber forest products -- South Africa , Natural resources -- South Africa , Rural poor -- South Africa , Rural development -- South Africa , Forests and forestry -- South Africa , Households -- Economic aspects -- South Africa , Natural resources, Communal -- South Africa , Commons -- South Africa , Forest ecology -- South Africa , Harvesting
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4736 , http://hdl.handle.net/10962/d1004604 , Non-timber forest products -- South Africa , Natural resources -- South Africa , Rural poor -- South Africa , Rural development -- South Africa , Forests and forestry -- South Africa , Households -- Economic aspects -- South Africa , Natural resources, Communal -- South Africa , Commons -- South Africa , Forest ecology -- South Africa , Harvesting
- Description: A great deal of research has demonstrated that Non-Timber Forest Products (NTFPs) play a crucial role in the livelihoods of the rural poor, and are particularly important to the most marginalised people throughout the developing world. However, these livelihood benefits are not without cost to the natural resource base that rural communities depend so heavily upon. The continued dependence on NTFPs as a major livelihood source must be contingent upon the minimisation of the level of disturbance created through this dependency. This study assesses the level of disturbance created through natural resource harvesting in eight study sites around South Africa, and applies a predictive conceptual model created by Shankaar et al. (2004b) to try and ascertain under what conditions the level of disturbance created through natural resource harvesting will be high. It assesses the three key factors that Shankaar et al. (2004b) identified (level of Local Ecological Knowledge (LEK), level of dependency and access to markets) in relation to the level of disturbance found at each of the study sites. It was found that there was a statistically significant relationship between the level of dependency and the level of disturbance, but there was no statistically significant relationship between either access to markets or the level of LEK and disturbance. Regulation of land use is a key issue, with weak local institutions in communal areas making effective resource management difficult. The significance of these findings is discussed, and priorities for future research are identified. This study adds to the body of knowledge related to NTFP harvesting and critically analyses the conflicts between the livelihood gains and the level of disturbance created through NTFP harvesting in an attempt to ascertain how livelihoods can be safeguarded. And in the longer-term, so that management strategies can be identified where resource extraction is not at the cost of undermining the very livelihoods that depend upon the natural resource base.
- Full Text:
- Date Issued: 2008
- Authors: Steele, Melita Zoë
- Date: 2008
- Subjects: Non-timber forest products -- South Africa , Natural resources -- South Africa , Rural poor -- South Africa , Rural development -- South Africa , Forests and forestry -- South Africa , Households -- Economic aspects -- South Africa , Natural resources, Communal -- South Africa , Commons -- South Africa , Forest ecology -- South Africa , Harvesting
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4736 , http://hdl.handle.net/10962/d1004604 , Non-timber forest products -- South Africa , Natural resources -- South Africa , Rural poor -- South Africa , Rural development -- South Africa , Forests and forestry -- South Africa , Households -- Economic aspects -- South Africa , Natural resources, Communal -- South Africa , Commons -- South Africa , Forest ecology -- South Africa , Harvesting
- Description: A great deal of research has demonstrated that Non-Timber Forest Products (NTFPs) play a crucial role in the livelihoods of the rural poor, and are particularly important to the most marginalised people throughout the developing world. However, these livelihood benefits are not without cost to the natural resource base that rural communities depend so heavily upon. The continued dependence on NTFPs as a major livelihood source must be contingent upon the minimisation of the level of disturbance created through this dependency. This study assesses the level of disturbance created through natural resource harvesting in eight study sites around South Africa, and applies a predictive conceptual model created by Shankaar et al. (2004b) to try and ascertain under what conditions the level of disturbance created through natural resource harvesting will be high. It assesses the three key factors that Shankaar et al. (2004b) identified (level of Local Ecological Knowledge (LEK), level of dependency and access to markets) in relation to the level of disturbance found at each of the study sites. It was found that there was a statistically significant relationship between the level of dependency and the level of disturbance, but there was no statistically significant relationship between either access to markets or the level of LEK and disturbance. Regulation of land use is a key issue, with weak local institutions in communal areas making effective resource management difficult. The significance of these findings is discussed, and priorities for future research are identified. This study adds to the body of knowledge related to NTFP harvesting and critically analyses the conflicts between the livelihood gains and the level of disturbance created through NTFP harvesting in an attempt to ascertain how livelihoods can be safeguarded. And in the longer-term, so that management strategies can be identified where resource extraction is not at the cost of undermining the very livelihoods that depend upon the natural resource base.
- Full Text:
- Date Issued: 2008
Negotiated cultural influence : a qualitative study of second year Chinese students at Nelson Mandela Metropolitan University in 2007 with specific reference to internet usage
- Authors: Yu, Yuanyuan
- Date: 2008
- Subjects: Internet in education , Internet -- Social aspects , Students, Foreign -- South Africa , Computer networks -- Social aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8375 , http://hdl.handle.net/10948/801 , Internet in education , Internet -- Social aspects , Students, Foreign -- South Africa , Computer networks -- Social aspects
- Description: This study aims to investigate the possible influence of Western culture on second-year Chinese students at the Nelson Mandela Metropolitan University (NMMU) in 2007 by focusing on their Internet usage. Roland Robertson’s theory of glocalization is employed as the theoretical framework in this study. The research design is qualitative in nature. Individual semi-structured interviews are the method of collecting research data while a thematic analysis is the means of analysing and interpreting the research data. The sample comprises twelve second-year Chinese students who are studying at the Nelson Mandela Metropolitan University (NMMU) in 2007 and have access to the Internet. This study has found that Western culture has exerted multi-faceted influences on the Chinese students through their Internet usage, and that they always negotiate such influences by selecting, adapting and appropriating what is useful in Western culture in an eclectic manner.
- Full Text:
- Date Issued: 2008
- Authors: Yu, Yuanyuan
- Date: 2008
- Subjects: Internet in education , Internet -- Social aspects , Students, Foreign -- South Africa , Computer networks -- Social aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8375 , http://hdl.handle.net/10948/801 , Internet in education , Internet -- Social aspects , Students, Foreign -- South Africa , Computer networks -- Social aspects
- Description: This study aims to investigate the possible influence of Western culture on second-year Chinese students at the Nelson Mandela Metropolitan University (NMMU) in 2007 by focusing on their Internet usage. Roland Robertson’s theory of glocalization is employed as the theoretical framework in this study. The research design is qualitative in nature. Individual semi-structured interviews are the method of collecting research data while a thematic analysis is the means of analysing and interpreting the research data. The sample comprises twelve second-year Chinese students who are studying at the Nelson Mandela Metropolitan University (NMMU) in 2007 and have access to the Internet. This study has found that Western culture has exerted multi-faceted influences on the Chinese students through their Internet usage, and that they always negotiate such influences by selecting, adapting and appropriating what is useful in Western culture in an eclectic manner.
- Full Text:
- Date Issued: 2008
Network-layer reservation TDM for ad-hoc 802.11 networks
- Authors: Duff, Kevin Craig
- Date: 2008
- Subjects: Computer networks -- Access control , Computers -- Access control , Computer networks -- Management , Time division multiple access , Ad hoc networks (Computer networks)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4574 , http://hdl.handle.net/10962/d1002773 , Computer networks -- Access control , Computers -- Access control , Computer networks -- Management , Time division multiple access , Ad hoc networks (Computer networks)
- Description: Ad-Hoc mesh networks offer great promise. Low-cost ad-hoc mesh networks can be built using popular IEEE 802.11 equipment, but such networks are unable to guarantee each node a fair share of bandwidth. Furthermore, hidden node problems cause collisions which can cripple the throughput of a network. This research proposes a novel mechanism which is able to overcome hidden node problems and provide fair bandwidth sharing among nodes on ad-hoc 802.11 networks, and can be implemented on existing network devices. The scheme uses TDM (time division multiplexing) with slot reservation. A distributed beacon packet latency measurement mechanism is used to achieve node synchronisation. The distributed nature of the mechanism makes it applicable to ad-hoc 802.11 networks, which can either grow or fragment dynamically.
- Full Text:
- Date Issued: 2008
- Authors: Duff, Kevin Craig
- Date: 2008
- Subjects: Computer networks -- Access control , Computers -- Access control , Computer networks -- Management , Time division multiple access , Ad hoc networks (Computer networks)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4574 , http://hdl.handle.net/10962/d1002773 , Computer networks -- Access control , Computers -- Access control , Computer networks -- Management , Time division multiple access , Ad hoc networks (Computer networks)
- Description: Ad-Hoc mesh networks offer great promise. Low-cost ad-hoc mesh networks can be built using popular IEEE 802.11 equipment, but such networks are unable to guarantee each node a fair share of bandwidth. Furthermore, hidden node problems cause collisions which can cripple the throughput of a network. This research proposes a novel mechanism which is able to overcome hidden node problems and provide fair bandwidth sharing among nodes on ad-hoc 802.11 networks, and can be implemented on existing network devices. The scheme uses TDM (time division multiplexing) with slot reservation. A distributed beacon packet latency measurement mechanism is used to achieve node synchronisation. The distributed nature of the mechanism makes it applicable to ad-hoc 802.11 networks, which can either grow or fragment dynamically.
- Full Text:
- Date Issued: 2008
Neuroprotective mechanisms of nevirapine and efavirenz in a model of neurodegeneration
- Authors: Zheve, Georgina Teurai
- Date: 2008
- Subjects: HIV infections -- Treatment AIDS (Disease) -- Treatment AIDS dementia complex -- Treatment Nervous system -- Degeneration -- Treatment Melatonin Neurotoxic agents Quinolinic acid
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:3807 , http://hdl.handle.net/10962/d1003285
- Description: AIDS Dementia Complex (ADC) is a neurodegenerative disorder implicated in HIV-1 infection that is associated with elevated levels of the neurotoxin, quinolinic acid (QA) which causes a cascade of events to occur, leading to the production of reactive oxygen species (ROS), these being ultimately responsible for oxidative neurotoxicity. In clinical studies, Non-nucleoside reverse transcriptase inhibitors (NNRTIs), efavirenz (EFV) and nevirapine (NVP) have been shown to potentially delay the progressive degeneration of neurons, thus reducing the frequency and neurological deficits associated with ADC. Despite these neuroprotective implications, there is still no biochemical data to demonstrate the mechanisms through which these agents offer neuroprotection. The present study aims to elucidate and further characterize the possible antioxidant and neuroprotective mechanisms of NVP and EFV in vitro and in vivo, using QA-induced neurotoxicity as a model. Research has demonstrated that antioxidants and metal chelators have the ability to offer neuroprotection against free radical induced injury and may be beneficial in the prevention or treatment of neurodegeneration. Hence the antioxidant and metal binding properties of these agents were investigated respectively. Inorganic studies, including the 1, 1-diphenyl-2 picrylhydrazyl (DPPH) assay, show that these agents readily scavenge free radicals in vitro, thus postulating the antioxidant property of these agents. The enhancement of superoxide radical generation and iron mediated Fenton reaction by QA is related to lipid peroxidation in biological systems, the extent of which was assayed using the nitroblue tetrazolium and thiobarbituric acid method respectively. Both agents significantly curtail QA-induced lipid peroxidation and potentially scavenge superoxide anions generated by cyanide in vitro. Furthermore, in vivo results demonstrate the ability of NVP and EFV to protect hippocampal neurons against lipid peroxidation induced by QA and superoxide radicals generated as a consequence thereof. The alleviation of QA-induced oxidative stress in vitro possibly occurs through the binding of iron (II) and / or iron (III), and this argument is further strengthened by the ability of EFV and not NVP to reduce iron (II)-induced lipid peroxidation in vitro directly. In addition the ferrozine and electrochemistry assay were used to measure the extent of iron (II) Fe[superscript 2+] and iron (III) Fe[superscript 3+] chelation activity. Both assays demonstrate that these agents bind iron (II) and iron (III), and prevent redox recycling of iron and subsequent complexation of Fe[superscript 2+] with QA which enhances neuronal damage. Both NNRTIs inhibit the endogenous biosynthesis of QA by inhibiting liver tryptophan 2, 3-dioxygenase activity in vivo and subsequently increasing hippocampal serotonin levels. Furthermore, these agents reduce the turnover of hippocampal serotonin to 5-hydroxyindole acetic acid. NVP and not EFV increase 5-hydroxyindole acetic acid and norepinephrine levels in the hippocampus. The results of the pineal indole metabolism study show that NVP increases the synthesis of melatonin, but decreases N-acetylserotonin, 5-hydroxyindole acetic acid and 5-hydroxytryptophol levels. Furthermore, it shows that EFV decreases 5-hydroxyindole acetic acid and melatonin synthesis. Behavioural studies using a Morris water maze show that the post-treatment of rats with NVP and EFV significantly improves QA-induced spatial memory deficits in the hippocampus. This study therefore provides novel information regarding the neuroprotective mechanisms of NVP and EFV. These findings strengthen the argument that these NNRTIs not only have antiviral effects but possess potential neuroprotective properties, which may contribute to the effectiveness of these drugs in the treatment of ADC.
- Full Text:
- Date Issued: 2008
- Authors: Zheve, Georgina Teurai
- Date: 2008
- Subjects: HIV infections -- Treatment AIDS (Disease) -- Treatment AIDS dementia complex -- Treatment Nervous system -- Degeneration -- Treatment Melatonin Neurotoxic agents Quinolinic acid
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:3807 , http://hdl.handle.net/10962/d1003285
- Description: AIDS Dementia Complex (ADC) is a neurodegenerative disorder implicated in HIV-1 infection that is associated with elevated levels of the neurotoxin, quinolinic acid (QA) which causes a cascade of events to occur, leading to the production of reactive oxygen species (ROS), these being ultimately responsible for oxidative neurotoxicity. In clinical studies, Non-nucleoside reverse transcriptase inhibitors (NNRTIs), efavirenz (EFV) and nevirapine (NVP) have been shown to potentially delay the progressive degeneration of neurons, thus reducing the frequency and neurological deficits associated with ADC. Despite these neuroprotective implications, there is still no biochemical data to demonstrate the mechanisms through which these agents offer neuroprotection. The present study aims to elucidate and further characterize the possible antioxidant and neuroprotective mechanisms of NVP and EFV in vitro and in vivo, using QA-induced neurotoxicity as a model. Research has demonstrated that antioxidants and metal chelators have the ability to offer neuroprotection against free radical induced injury and may be beneficial in the prevention or treatment of neurodegeneration. Hence the antioxidant and metal binding properties of these agents were investigated respectively. Inorganic studies, including the 1, 1-diphenyl-2 picrylhydrazyl (DPPH) assay, show that these agents readily scavenge free radicals in vitro, thus postulating the antioxidant property of these agents. The enhancement of superoxide radical generation and iron mediated Fenton reaction by QA is related to lipid peroxidation in biological systems, the extent of which was assayed using the nitroblue tetrazolium and thiobarbituric acid method respectively. Both agents significantly curtail QA-induced lipid peroxidation and potentially scavenge superoxide anions generated by cyanide in vitro. Furthermore, in vivo results demonstrate the ability of NVP and EFV to protect hippocampal neurons against lipid peroxidation induced by QA and superoxide radicals generated as a consequence thereof. The alleviation of QA-induced oxidative stress in vitro possibly occurs through the binding of iron (II) and / or iron (III), and this argument is further strengthened by the ability of EFV and not NVP to reduce iron (II)-induced lipid peroxidation in vitro directly. In addition the ferrozine and electrochemistry assay were used to measure the extent of iron (II) Fe[superscript 2+] and iron (III) Fe[superscript 3+] chelation activity. Both assays demonstrate that these agents bind iron (II) and iron (III), and prevent redox recycling of iron and subsequent complexation of Fe[superscript 2+] with QA which enhances neuronal damage. Both NNRTIs inhibit the endogenous biosynthesis of QA by inhibiting liver tryptophan 2, 3-dioxygenase activity in vivo and subsequently increasing hippocampal serotonin levels. Furthermore, these agents reduce the turnover of hippocampal serotonin to 5-hydroxyindole acetic acid. NVP and not EFV increase 5-hydroxyindole acetic acid and norepinephrine levels in the hippocampus. The results of the pineal indole metabolism study show that NVP increases the synthesis of melatonin, but decreases N-acetylserotonin, 5-hydroxyindole acetic acid and 5-hydroxytryptophol levels. Furthermore, it shows that EFV decreases 5-hydroxyindole acetic acid and melatonin synthesis. Behavioural studies using a Morris water maze show that the post-treatment of rats with NVP and EFV significantly improves QA-induced spatial memory deficits in the hippocampus. This study therefore provides novel information regarding the neuroprotective mechanisms of NVP and EFV. These findings strengthen the argument that these NNRTIs not only have antiviral effects but possess potential neuroprotective properties, which may contribute to the effectiveness of these drugs in the treatment of ADC.
- Full Text:
- Date Issued: 2008
Newsroom convergence at the Mail & Guardian: a case study
- Authors: Van Noort, Elvira Esmeralda
- Date: 2008
- Subjects: Mail & Guardian Convergence (Telecommunication) Journalism -- Management -- South Africa Mass media -- Management -- South Africa Journalism -- Technological innovations -- South Africa Online journalism -- South Africa Broadcast journalism -- South Africa Mass media -- Ownership Digital media -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3490 , http://hdl.handle.net/10962/d1002945
- Description: This case study researches newsroom convergence as a process at the Mail & Guardian newspaper and their online edition the Mail & Guardian Online. It focuses on the reporters’ and editors’ attitudes towards newsroom convergence and on cultural resistance against change; one of the major challenges in the process. With structured interviews, observations and questionnaires it was analysed that communication problems between the newsrooms, different production cycles and time management issues are other prominent difficulties. The case study furthermore provides a snapshot of the convergence phenomenon as a process in a particular South African news organisation. The outcomes could not only assist other news companies with convergence plans but also be used as a pilot study for further research on converged newsrooms in South Africa.
- Full Text:
- Date Issued: 2008
- Authors: Van Noort, Elvira Esmeralda
- Date: 2008
- Subjects: Mail & Guardian Convergence (Telecommunication) Journalism -- Management -- South Africa Mass media -- Management -- South Africa Journalism -- Technological innovations -- South Africa Online journalism -- South Africa Broadcast journalism -- South Africa Mass media -- Ownership Digital media -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3490 , http://hdl.handle.net/10962/d1002945
- Description: This case study researches newsroom convergence as a process at the Mail & Guardian newspaper and their online edition the Mail & Guardian Online. It focuses on the reporters’ and editors’ attitudes towards newsroom convergence and on cultural resistance against change; one of the major challenges in the process. With structured interviews, observations and questionnaires it was analysed that communication problems between the newsrooms, different production cycles and time management issues are other prominent difficulties. The case study furthermore provides a snapshot of the convergence phenomenon as a process in a particular South African news organisation. The outcomes could not only assist other news companies with convergence plans but also be used as a pilot study for further research on converged newsrooms in South Africa.
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- Date Issued: 2008
No other world: the poetry of Don Maclennan
- Authors: Robinson, Brendon Kimbale
- Date: 2008
- Subjects: Maclennan, Don Maclennan, Don -- Criticism and interpretation South African poetry (English) -- History and criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2221 , http://hdl.handle.net/10962/d1002264
- Description: This is a study of the poetry of Don Maclennan in four chapters. Chapter One explores the poetry's deep involvement with the immediate world, and with the being that encounters it. Chapter Two examines the corpus's mistrust of abstract thought, and its suggestions for alternative ways of intepreting (or at least approaching an interpretation of) our existential situation. Chapter Three deals with Maclennan's writing on the subject of death, while the final chapter looks at the response of the poetry to the fact of death: put simply, this is to learn to love the situation we are in, and to record our thoughts for future generations, thus reaching beyond death to share with others the necessarily unique experience of our one and only life.
- Full Text:
- Date Issued: 2008
- Authors: Robinson, Brendon Kimbale
- Date: 2008
- Subjects: Maclennan, Don Maclennan, Don -- Criticism and interpretation South African poetry (English) -- History and criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2221 , http://hdl.handle.net/10962/d1002264
- Description: This is a study of the poetry of Don Maclennan in four chapters. Chapter One explores the poetry's deep involvement with the immediate world, and with the being that encounters it. Chapter Two examines the corpus's mistrust of abstract thought, and its suggestions for alternative ways of intepreting (or at least approaching an interpretation of) our existential situation. Chapter Three deals with Maclennan's writing on the subject of death, while the final chapter looks at the response of the poetry to the fact of death: put simply, this is to learn to love the situation we are in, and to record our thoughts for future generations, thus reaching beyond death to share with others the necessarily unique experience of our one and only life.
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- Date Issued: 2008
Normative indications for Xhosa-speaking unskilled workers on the trail making test and the stroop test
- Authors: Andrews, Karen Anne Hope
- Date: 2008
- Subjects: Neuropsychology , Neuropsychological tests -- Sex differences , Educational tests and measurements -- Sex differences , Xhosa (African people) -- Education
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:2926 , http://hdl.handle.net/10962/d1002435 , Neuropsychology , Neuropsychological tests -- Sex differences , Educational tests and measurements -- Sex differences , Xhosa (African people) -- Education
- Description: The aim of the study was to produce preliminary normative indications for the Trail Making Test and the Stroop Test, administered in English, on a non-clinical sample of black, Xhosa-speaking, unskilled individuals (N = 33), with an educational level of 11 – 12 years, in two age categories (18 –29 and 30 – 40 years). The sample was equally distributed for gender and level of education. Participants, who were required to have a basic proficiency in English, were from traditionally black township schools with relatively disadvantaged quality of education. Within-sample age and gender effects were investigated. There were no significant age effects on the Trail Making Test, whereas there was one significant difference between age groups on the Stroop Test with respect to the Color-Word task, and a result that strongly approached significance on the Word task, with the younger group performing better than the older group. There were no significant gender effects on the Trail Making Test, whereas there was one significant difference between genders on the Stroop Test with respect to the Word task, and a result that approached significance on the Color task, with females performing better than males. Normative indications for both measures were compared to available normative data on western populations with higher levels and more advantaged quality of education. This comparison revealed consistently poorer performances for both the Trail Making Test and the Stroop Test, confirming the need for localised normative datasets to facilitate accurate neuropsychological diagnoses on culturally disadvantaged individuals.
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- Date Issued: 2008
- Authors: Andrews, Karen Anne Hope
- Date: 2008
- Subjects: Neuropsychology , Neuropsychological tests -- Sex differences , Educational tests and measurements -- Sex differences , Xhosa (African people) -- Education
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:2926 , http://hdl.handle.net/10962/d1002435 , Neuropsychology , Neuropsychological tests -- Sex differences , Educational tests and measurements -- Sex differences , Xhosa (African people) -- Education
- Description: The aim of the study was to produce preliminary normative indications for the Trail Making Test and the Stroop Test, administered in English, on a non-clinical sample of black, Xhosa-speaking, unskilled individuals (N = 33), with an educational level of 11 – 12 years, in two age categories (18 –29 and 30 – 40 years). The sample was equally distributed for gender and level of education. Participants, who were required to have a basic proficiency in English, were from traditionally black township schools with relatively disadvantaged quality of education. Within-sample age and gender effects were investigated. There were no significant age effects on the Trail Making Test, whereas there was one significant difference between age groups on the Stroop Test with respect to the Color-Word task, and a result that strongly approached significance on the Word task, with the younger group performing better than the older group. There were no significant gender effects on the Trail Making Test, whereas there was one significant difference between genders on the Stroop Test with respect to the Word task, and a result that approached significance on the Color task, with females performing better than males. Normative indications for both measures were compared to available normative data on western populations with higher levels and more advantaged quality of education. This comparison revealed consistently poorer performances for both the Trail Making Test and the Stroop Test, confirming the need for localised normative datasets to facilitate accurate neuropsychological diagnoses on culturally disadvantaged individuals.
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- Date Issued: 2008
Novel aspects of platinum-amine coordination compounds: their chemistry and anticancer application
- Authors: Bouwer, Yolanda
- Date: 2008
- Subjects: Coordination compounds , Platinum compounds , Antineoplastic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10444 , http://hdl.handle.net/10948/d1021052
- Description: The aim in this thesis, was to synthesize novel platinum coordination compounds, in order to develop compounds with improved anticancer action which could lead to an improved understanding of the mechanism by which they operate and at the same time, improve synthetic methods for their products. The initial work included the development of a novel synthetic method for 1R,2R-diaminocyclohexaneoxalato-platinum(II) (oxaliplatin), by using an essentially non-aqueous solvent medium and direct ligand exchange at elevated temperatures. This was done by a study of the kinetics of the reaction in a variety of conditions; such as relative reagent concentrations and ratios as well as solvent mixtures. An effective method was developed which could be applied industrially. An international patent was taken out on this method. Various amine complexes of platinum(II) were synthesized using chloro, bromo and oxalato groups as leaving groups. The non-leaving groups were selected having certain specific characteristics in mind. Novel mononitroplatinum(IV) complexes were synthesized, mostly with oxalato leaving groups. One of these in particular, had excellent anticancer behaviour. Another trichloromononitro complex was also synthesized with very good anticancer properties. Two international patents were filed for the latter two compounds. As far as possible, all compounds were studied by spectrometric, chromatographic and thermal methods. They were also tested against 3 cancer cell lines namely cervical (Hela), Colon (HT29) and Breast (MCF7) cancer cells.
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- Date Issued: 2008
- Authors: Bouwer, Yolanda
- Date: 2008
- Subjects: Coordination compounds , Platinum compounds , Antineoplastic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10444 , http://hdl.handle.net/10948/d1021052
- Description: The aim in this thesis, was to synthesize novel platinum coordination compounds, in order to develop compounds with improved anticancer action which could lead to an improved understanding of the mechanism by which they operate and at the same time, improve synthetic methods for their products. The initial work included the development of a novel synthetic method for 1R,2R-diaminocyclohexaneoxalato-platinum(II) (oxaliplatin), by using an essentially non-aqueous solvent medium and direct ligand exchange at elevated temperatures. This was done by a study of the kinetics of the reaction in a variety of conditions; such as relative reagent concentrations and ratios as well as solvent mixtures. An effective method was developed which could be applied industrially. An international patent was taken out on this method. Various amine complexes of platinum(II) were synthesized using chloro, bromo and oxalato groups as leaving groups. The non-leaving groups were selected having certain specific characteristics in mind. Novel mononitroplatinum(IV) complexes were synthesized, mostly with oxalato leaving groups. One of these in particular, had excellent anticancer behaviour. Another trichloromononitro complex was also synthesized with very good anticancer properties. Two international patents were filed for the latter two compounds. As far as possible, all compounds were studied by spectrometric, chromatographic and thermal methods. They were also tested against 3 cancer cell lines namely cervical (Hela), Colon (HT29) and Breast (MCF7) cancer cells.
- Full Text:
- Date Issued: 2008