A model for privacy-aware presence management in mobile communications
- Authors: Ophoff, Jacobus Albertus
- Date: 2011
- Subjects: Mobile communications systems , Mobile communication systems -- Management
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9757 , http://hdl.handle.net/10948/1354 , Mobile communications systems , Mobile communication systems -- Management
- Description: As humans we find communicating natural and compelling. Over the centuries we have created many innovations which enable and improve communication between people; during the past decade mobile phone networks have brought about a technological revolution in this area. Never before have people been so connected to one another. Today we have the ability to communicate with almost anyone, anytime, anywhere. Our increased connectivity and reachability also leads to new issues and challenges that we need to deal with. When we phone someone we expect an instant connection, and when this does not occur it can be frustrating. On the other hand it is equally disruptive to receive a call when one is busy with an important task or in a situation where communication is inappropriate. Social protocol dictates that we try to minimize such situations for the benefit of others nearby and for ourselves. This management of communications is a constant and difficult task. Using presence – which signals a person’s availability and willingness to communicate – is a solution to this problem. Such information can benefit communication partners by increasing the likelihood of a successful connection and decreasing disruptions. This research addresses the problem of staying connected while keeping control over mobile communications. It adopts a design-science research paradigm, with the primary research artifact being a model for privacy-aware presence management in mobile communications. As part of the model development knowledge contributions are made in several ways. Existing knowledge about the problem area is extended through a quantitative analysis of mobile communications management. This analysis uses a novel survey, collecting useful empirical data for future research. This includes how people currently manage their communications and what features they expect from a potential “call management” system. The examination and use of presence standards, as a foundation for the model, provides a comparison of the main presence technologies available today. A focus on privacy features identifies several shortcomings in standards which, if addressed, can help to improve and make these standards more complete. The model stresses the privacy of potentially sensitive presence information. A unique perspective based on social relationship theories is adopted. The use of relationship groups not only makes logical sense but also assists in the management of presence information and extends existing standards. Finally, the evaluation of the model demonstrates the feasibility of a practical implementation as well the ability to extend the model in next generation mobile networks. Thus the model presents a solid foundation for the development of future services. In these ways the proposed model contributes positively towards balancing efficient mobile communications with the need for privacy-awareness.
- Full Text:
- Date Issued: 2011
- Authors: Ophoff, Jacobus Albertus
- Date: 2011
- Subjects: Mobile communications systems , Mobile communication systems -- Management
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9757 , http://hdl.handle.net/10948/1354 , Mobile communications systems , Mobile communication systems -- Management
- Description: As humans we find communicating natural and compelling. Over the centuries we have created many innovations which enable and improve communication between people; during the past decade mobile phone networks have brought about a technological revolution in this area. Never before have people been so connected to one another. Today we have the ability to communicate with almost anyone, anytime, anywhere. Our increased connectivity and reachability also leads to new issues and challenges that we need to deal with. When we phone someone we expect an instant connection, and when this does not occur it can be frustrating. On the other hand it is equally disruptive to receive a call when one is busy with an important task or in a situation where communication is inappropriate. Social protocol dictates that we try to minimize such situations for the benefit of others nearby and for ourselves. This management of communications is a constant and difficult task. Using presence – which signals a person’s availability and willingness to communicate – is a solution to this problem. Such information can benefit communication partners by increasing the likelihood of a successful connection and decreasing disruptions. This research addresses the problem of staying connected while keeping control over mobile communications. It adopts a design-science research paradigm, with the primary research artifact being a model for privacy-aware presence management in mobile communications. As part of the model development knowledge contributions are made in several ways. Existing knowledge about the problem area is extended through a quantitative analysis of mobile communications management. This analysis uses a novel survey, collecting useful empirical data for future research. This includes how people currently manage their communications and what features they expect from a potential “call management” system. The examination and use of presence standards, as a foundation for the model, provides a comparison of the main presence technologies available today. A focus on privacy features identifies several shortcomings in standards which, if addressed, can help to improve and make these standards more complete. The model stresses the privacy of potentially sensitive presence information. A unique perspective based on social relationship theories is adopted. The use of relationship groups not only makes logical sense but also assists in the management of presence information and extends existing standards. Finally, the evaluation of the model demonstrates the feasibility of a practical implementation as well the ability to extend the model in next generation mobile networks. Thus the model presents a solid foundation for the development of future services. In these ways the proposed model contributes positively towards balancing efficient mobile communications with the need for privacy-awareness.
- Full Text:
- Date Issued: 2011
Thermal degradation of diamond compacts: a TEM investigation
- Authors: Westraadt, Johan Ewald
- Date: 2011
- Subjects: Materials -- Thermal properties Chemical weathering
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/10829 , vital:26827
- Description: Diamond compacts consist of fine diamond grains bonded together by using high pressure and high temperature. In this study transmission electron microscopy (TEM)was used to study thermal degradation of diamond compacts. Three different types of diamond compacts – namely cobalt polycrystalline diamond (PCD), calcium carbonate PCD, and diamond-SiC composites – were investigated with TEM to understand the processes that occur during synthesis. These compacts were then heated in inert atmospheres and the chemical changes studied with TEM. It was found that PCD, using cobalt as a bonding agent, will degrade after exposure to temperatures above 750ºC. The cobalt pools contain tungsten in solid solution. During heat treatment above 700ºC the solid solution tungsten combines with cobalt and dissolved carbon to form η-phase particles at the cobalt/diamond interface. At higher temperatures or insufficient tungsten levels the rate of dissolved carbon, into the cobalt pool, is too high and the excess carbon will form as graphite in the cobalt pool. Increased levels of solid solution tungsten, in the cobalt, is expected to delay the onset of graphitization in the diamond compact, thereby increasing the thermal stability of the diamond compact. Non-metallic PCD using calcium carbonate as a bonding agent was successfully sintered in this study. TEM revealed similar micro-structural features as in cobalt based PCD. No signs of thermal degradation were found after exposure to 1200ºC in vacuum for this PCD. Contaminants introduced during processing prevented a detailed study of the binder in this system. The effect of substitutional metal atoms and plastic deformation of diamond on the thermal stability of diamond-SiC composites were investigated. A piston cylinder press was developed and used to synthesize diamond-SiC composites with different levels of plastically deformed diamond. It was concluded that substitutional metal atoms and plastic deformation of diamond grains play no role in the thermal degradation of diamond compacts at 750ºC. The thermal degradation of cobalt PCD is therefore completely determined by the cobalt/diamond interaction at 750ºC.
- Full Text:
- Date Issued: 2011
- Authors: Westraadt, Johan Ewald
- Date: 2011
- Subjects: Materials -- Thermal properties Chemical weathering
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/10829 , vital:26827
- Description: Diamond compacts consist of fine diamond grains bonded together by using high pressure and high temperature. In this study transmission electron microscopy (TEM)was used to study thermal degradation of diamond compacts. Three different types of diamond compacts – namely cobalt polycrystalline diamond (PCD), calcium carbonate PCD, and diamond-SiC composites – were investigated with TEM to understand the processes that occur during synthesis. These compacts were then heated in inert atmospheres and the chemical changes studied with TEM. It was found that PCD, using cobalt as a bonding agent, will degrade after exposure to temperatures above 750ºC. The cobalt pools contain tungsten in solid solution. During heat treatment above 700ºC the solid solution tungsten combines with cobalt and dissolved carbon to form η-phase particles at the cobalt/diamond interface. At higher temperatures or insufficient tungsten levels the rate of dissolved carbon, into the cobalt pool, is too high and the excess carbon will form as graphite in the cobalt pool. Increased levels of solid solution tungsten, in the cobalt, is expected to delay the onset of graphitization in the diamond compact, thereby increasing the thermal stability of the diamond compact. Non-metallic PCD using calcium carbonate as a bonding agent was successfully sintered in this study. TEM revealed similar micro-structural features as in cobalt based PCD. No signs of thermal degradation were found after exposure to 1200ºC in vacuum for this PCD. Contaminants introduced during processing prevented a detailed study of the binder in this system. The effect of substitutional metal atoms and plastic deformation of diamond on the thermal stability of diamond-SiC composites were investigated. A piston cylinder press was developed and used to synthesize diamond-SiC composites with different levels of plastically deformed diamond. It was concluded that substitutional metal atoms and plastic deformation of diamond grains play no role in the thermal degradation of diamond compacts at 750ºC. The thermal degradation of cobalt PCD is therefore completely determined by the cobalt/diamond interaction at 750ºC.
- Full Text:
- Date Issued: 2011
Synthesis and evaluation of novel HIV-1 enzyme inhibitors
- Olomola, Temitope Oloruntoba
- Authors: Olomola, Temitope Oloruntoba
- Date: 2011
- Subjects: HIV infections -- Treatment HIV infections -- Chemotherapy HIV (Viruses) Enzyme inhibitors AZT (Drug) Reverse transcriptase Proteolytic enzymes Ligands Psoralens Resorcinol
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4369 , http://hdl.handle.net/10962/d1005034
- Description: This study has involved the design, synthesis and evaluation of novel HIV-1 enzyme inhibitors accessed by synthetic elaboration of Baylis-Hillman adducts. Several series of complex coumarin-AZT and cinnamate ester-AZT conjugates have been prepared, in high yields, by exploiting the click reaction between appropriate Baylis-Hillman derived precursors and azidothymidine (AZT), all of which have been fully characterised using spectroscopic techniques. These conjugates, designed as potential dual-action HIV-1 inhibitors, were tested against the appropriate HIV-1 enzymes, i.e. HIV-1 reverse transcriptase and protease or HIV-1 reverse transcriptase and integrase. A number of the ligands have exhibited % inhibition levels and IC50 values comparable to drugs in clinical use, permitting their identification as lead compounds for the development of novel dual-action inhibitors. In silico docking of selected ligands into the active sites of the respective enzymes has provided useful insight into binding conformations and potential hydrogen-bonding interactions with active-site amino acid residues. A series of furocoumarin carboxamide derivatives have been synthesised in four steps starting from resorcinol and these compounds have also been tested for HIV-1 integrase inhibition activity. The structures of unexpected products isolated from Aza-Baylis-Hillman reactions of N-tosylaldimines have been elucidated by spectroscopic analysis, and confirmed by single crystal X-ray analysis. A mechanism for what appears to be an unprecedented transformation has been proposed. Microwave-assisted SeO₂ oxidation of Baylis-Hillman-derived 3-methylcoumarins has provided convenient and efficient access to coumarin-3-carbaldehydes, and a pilot study has revealed the potential of these coumarin-3-carbaldehydes as scaffolds for the construction of tricyclic compounds. The HCl-catalysed reaction of tert-butyl acrylate derived Baylis-Hillman adducts has been shown to afford 3-(chloromethyl)coumarins and α-(chloromethyl)cinnamic acids, the Zstereochemistry of the latter being established by X-ray crystallography. ¹H NMR-based experimental kinetic and DFT-level theoretical studies have been undertaken to establish the reaction sequence and other mechanistic details. Base-catalysed cyclisation on the other hand, has been shown to afford 2H-chromene rather than coumarin derivatives.
- Full Text:
- Date Issued: 2011
- Authors: Olomola, Temitope Oloruntoba
- Date: 2011
- Subjects: HIV infections -- Treatment HIV infections -- Chemotherapy HIV (Viruses) Enzyme inhibitors AZT (Drug) Reverse transcriptase Proteolytic enzymes Ligands Psoralens Resorcinol
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4369 , http://hdl.handle.net/10962/d1005034
- Description: This study has involved the design, synthesis and evaluation of novel HIV-1 enzyme inhibitors accessed by synthetic elaboration of Baylis-Hillman adducts. Several series of complex coumarin-AZT and cinnamate ester-AZT conjugates have been prepared, in high yields, by exploiting the click reaction between appropriate Baylis-Hillman derived precursors and azidothymidine (AZT), all of which have been fully characterised using spectroscopic techniques. These conjugates, designed as potential dual-action HIV-1 inhibitors, were tested against the appropriate HIV-1 enzymes, i.e. HIV-1 reverse transcriptase and protease or HIV-1 reverse transcriptase and integrase. A number of the ligands have exhibited % inhibition levels and IC50 values comparable to drugs in clinical use, permitting their identification as lead compounds for the development of novel dual-action inhibitors. In silico docking of selected ligands into the active sites of the respective enzymes has provided useful insight into binding conformations and potential hydrogen-bonding interactions with active-site amino acid residues. A series of furocoumarin carboxamide derivatives have been synthesised in four steps starting from resorcinol and these compounds have also been tested for HIV-1 integrase inhibition activity. The structures of unexpected products isolated from Aza-Baylis-Hillman reactions of N-tosylaldimines have been elucidated by spectroscopic analysis, and confirmed by single crystal X-ray analysis. A mechanism for what appears to be an unprecedented transformation has been proposed. Microwave-assisted SeO₂ oxidation of Baylis-Hillman-derived 3-methylcoumarins has provided convenient and efficient access to coumarin-3-carbaldehydes, and a pilot study has revealed the potential of these coumarin-3-carbaldehydes as scaffolds for the construction of tricyclic compounds. The HCl-catalysed reaction of tert-butyl acrylate derived Baylis-Hillman adducts has been shown to afford 3-(chloromethyl)coumarins and α-(chloromethyl)cinnamic acids, the Zstereochemistry of the latter being established by X-ray crystallography. ¹H NMR-based experimental kinetic and DFT-level theoretical studies have been undertaken to establish the reaction sequence and other mechanistic details. Base-catalysed cyclisation on the other hand, has been shown to afford 2H-chromene rather than coumarin derivatives.
- Full Text:
- Date Issued: 2011
African traditional medicine-antiretroviral interactions : effects of Sutherlandia frutescens on the pharmacokinetics of Atazanavir
- Authors: Müller, Adrienne Carmel
- Date: 2011 , 2011-03-28
- Subjects: Antiretroviral agents , Medicinal plants , Traditional medicine , AIDS (Disease) -- Treatment , HIV infections -- Drug therapy , Drug interactions , Pharmacokinetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3859 , http://hdl.handle.net/10962/d1013373
- Description: In response to the urgent call for investigations into antiretroviral (ARV)-African traditional medicine (ATM) interactions, this research was undertaken to ascertain whether chronic administration of the ATM, Sutherlandia frutescens (SF) may alter the bioavailability of the protease inhibitor (PI), atazanavir (ATV), which may impact on the safety or efficacy of the ARV. Prior to investigating a potential interaction between ATV and SF in vitro and in vivo, a high performance liquid chromatography method with ultraviolet detection (HPLC-UV) was developed and validated for the bioanalysis of ATV in human plasma and liver microsomes. An improved and efficient analytical method with minimal use of solvents and short run time was achieved in comparison to methods published in the literature. In addition, the method was selective, linear, accurate and precise for quantitative analysis of ATV in these studies. Molecular docking studies were conducted to compare the binding modes and affinities of ATV and two major SF constituents, Sutherlandioside B and Sutherlandin C, with the efflux transporter, P-glycoprotein (P-gp) and the CYP450 isoenzyme, CYP3A4 to determine the potential for these phytochemicals to competitively inhibit the binding of ATV to these two proteins, which are mediators of absorption and metabolism. These studies revealed that modulation of P-gp transport of ATV by Sutherlandioside B and Sutherlandin C was not likely to occur via competitive inhibition. The results further indicated that weak competitive inhibition of CYP3A4 may possibly occur in the presence of either of these two SF constituents. The Caco-2 cell line was used as an in vitro model of human intestinal absorption. Accumulation studies in these cells were conducted to ascertain whether extracts and constituents of SF have the ability to alter the absorption of ATV. The results showed that the aqueous extract of SF significantly reduced ATV accumulation, suggesting decreased ATV absorption, whilst a triterpenoid glycoside fraction isolated from SF exhibited an opposing effect. Analogous responses were elicited by the aqueous extract and a triterpenoid glycoside fraction in similar accumulation studies in P-gp overexpressing Madin–Darby Canine Kidney Strain II cells (MDCKII-MDR1), which signified that the effects of this extract and component on ATV transport in the Caco-2 cells were P-gp-mediated. The quantitative analysis of ATV in human liver microsomes after co-incubation with extracts and components of SF was conducted to determine the effects of SF on the metabolism of ATV. The aqueous and methanolic extracts of SF inhibited ATV metabolism, whilst the triterpenoid glycoside fraction had a converse effect. Analogous effects by the extracts were demonstrated in experiments conducted in CYP3A4-transfected microsomes, suggesting that the inhibition of ATV metabolism in the liver microsomes by these SF extracts was CYP3A4-mediated. A combination of Sutherlandiosides C and D also inhibited CYP3A4-mediated ATV metabolism, which was in contrast to the response elicited by the triterpenoid fraction in the liver microsomes, where other unidentified compounds, shown to be present therein, may have contributed to the activation of ATV metabolism. The in vitro studies revealed the potential for SF to alter the bioavailability of ATV, therefore a clinical study in which the effect of a multiple dose regimen of SF on the pharmacokinetics (PK) of a single dose of ATV was conducted in healthy male volunteers. The statistical analysis showed that the 90 % confidence intervals around the geometric mean ratios (ATV + SF/ATV alone) for both Cmax and AUC0-24 hours, fell well below the lower limit of the "no-effect" boundary of 0.8 – 1.25, implying that the bioavailability of ATV was significantly reduced in this cohort of subjects. It may thus be concluded that if the reduction in bioavailability observed in this clinical study is found to be clinically relevant, co-administration of SF commercial dosage forms and ATV in HIV/AIDS patients may potentially result in subtherapeutic ATV levels, which may in turn contribute to ATV resistance and/or treatment failure. This research has therefore highlighted the potential risk for toxicity or lack of efficacy of ARV regimens which may result when ATMs and PIs are used concurrently and that patients and health care practitioners alike should be aware of these perils.
- Full Text:
- Date Issued: 2011
- Authors: Müller, Adrienne Carmel
- Date: 2011 , 2011-03-28
- Subjects: Antiretroviral agents , Medicinal plants , Traditional medicine , AIDS (Disease) -- Treatment , HIV infections -- Drug therapy , Drug interactions , Pharmacokinetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3859 , http://hdl.handle.net/10962/d1013373
- Description: In response to the urgent call for investigations into antiretroviral (ARV)-African traditional medicine (ATM) interactions, this research was undertaken to ascertain whether chronic administration of the ATM, Sutherlandia frutescens (SF) may alter the bioavailability of the protease inhibitor (PI), atazanavir (ATV), which may impact on the safety or efficacy of the ARV. Prior to investigating a potential interaction between ATV and SF in vitro and in vivo, a high performance liquid chromatography method with ultraviolet detection (HPLC-UV) was developed and validated for the bioanalysis of ATV in human plasma and liver microsomes. An improved and efficient analytical method with minimal use of solvents and short run time was achieved in comparison to methods published in the literature. In addition, the method was selective, linear, accurate and precise for quantitative analysis of ATV in these studies. Molecular docking studies were conducted to compare the binding modes and affinities of ATV and two major SF constituents, Sutherlandioside B and Sutherlandin C, with the efflux transporter, P-glycoprotein (P-gp) and the CYP450 isoenzyme, CYP3A4 to determine the potential for these phytochemicals to competitively inhibit the binding of ATV to these two proteins, which are mediators of absorption and metabolism. These studies revealed that modulation of P-gp transport of ATV by Sutherlandioside B and Sutherlandin C was not likely to occur via competitive inhibition. The results further indicated that weak competitive inhibition of CYP3A4 may possibly occur in the presence of either of these two SF constituents. The Caco-2 cell line was used as an in vitro model of human intestinal absorption. Accumulation studies in these cells were conducted to ascertain whether extracts and constituents of SF have the ability to alter the absorption of ATV. The results showed that the aqueous extract of SF significantly reduced ATV accumulation, suggesting decreased ATV absorption, whilst a triterpenoid glycoside fraction isolated from SF exhibited an opposing effect. Analogous responses were elicited by the aqueous extract and a triterpenoid glycoside fraction in similar accumulation studies in P-gp overexpressing Madin–Darby Canine Kidney Strain II cells (MDCKII-MDR1), which signified that the effects of this extract and component on ATV transport in the Caco-2 cells were P-gp-mediated. The quantitative analysis of ATV in human liver microsomes after co-incubation with extracts and components of SF was conducted to determine the effects of SF on the metabolism of ATV. The aqueous and methanolic extracts of SF inhibited ATV metabolism, whilst the triterpenoid glycoside fraction had a converse effect. Analogous effects by the extracts were demonstrated in experiments conducted in CYP3A4-transfected microsomes, suggesting that the inhibition of ATV metabolism in the liver microsomes by these SF extracts was CYP3A4-mediated. A combination of Sutherlandiosides C and D also inhibited CYP3A4-mediated ATV metabolism, which was in contrast to the response elicited by the triterpenoid fraction in the liver microsomes, where other unidentified compounds, shown to be present therein, may have contributed to the activation of ATV metabolism. The in vitro studies revealed the potential for SF to alter the bioavailability of ATV, therefore a clinical study in which the effect of a multiple dose regimen of SF on the pharmacokinetics (PK) of a single dose of ATV was conducted in healthy male volunteers. The statistical analysis showed that the 90 % confidence intervals around the geometric mean ratios (ATV + SF/ATV alone) for both Cmax and AUC0-24 hours, fell well below the lower limit of the "no-effect" boundary of 0.8 – 1.25, implying that the bioavailability of ATV was significantly reduced in this cohort of subjects. It may thus be concluded that if the reduction in bioavailability observed in this clinical study is found to be clinically relevant, co-administration of SF commercial dosage forms and ATV in HIV/AIDS patients may potentially result in subtherapeutic ATV levels, which may in turn contribute to ATV resistance and/or treatment failure. This research has therefore highlighted the potential risk for toxicity or lack of efficacy of ARV regimens which may result when ATMs and PIs are used concurrently and that patients and health care practitioners alike should be aware of these perils.
- Full Text:
- Date Issued: 2011
The influence of genetic relatedness on sociality and demography of female African elephants
- Authors: Munishi, Linus Kasian
- Date: 2011
- Subjects: African elephant , Wildlife conservation , Elephants -- Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10711 , http://hdl.handle.net/10948/d1011612 , African elephant , Wildlife conservation , Elephants -- Africa
- Description: Many elephant populations across Africa were or are being devastated by poaching and habitat loss, making population and range size for the species important issues of conservation concern in elephant ranging areas, including Tarangire National Park (TNP). Poaching and/or overhunting are known to have direct effects on the demography of elephant populations. The current understanding of the indirect effects of poaching on the sociality and demography of elephant populations is relatively poor, both at the group and an individual level. In this thesis the importance of genetic relatedness (as influenced by poaching) on sociality and demography of the female elephants was studied, using a combination of genetic, observation of behaviour and two decades of demography data collected from the northern subpopulation of TNP. I investigated and characterized the relatedness categories within elephant groups. Using a conceptual model for group size analysis in aggregation economies, I hypothesized that elephant populations subject to social disruptions due to poaching would exhibit characteristics of the free entry model, whereas more stable, closed populations would better fit the group-controlled model. I present a rare quantitative analysis of genetic relatedness and group size patterns among groups of adult female elephants in two wild populations: one in Tarangire National Park (TNP), Tanzania, and another in Addo Elephant National Park (AENP), South Africa. I demonstrate that the group size in African elephant populations is governed by genetic relatedness, and that poaching/overhunting has a significant influence upon the apparent group formation and size in elephants. I then focused on the effect of relatedness on agonistic interactions between adult females. I hypothesized that individual-based aggressive interactions among adult female African elephants would vary according to degree of kinship, with closely related dyads showing less aggression towards each other in resource-limited environments, thereby leading to indirect fitness benefits for individuals. As predicted, females did not show agonistic interactions to their close kin most often, and the frequency and intensity of aggressive interactions was inversely related to the degree of relatedness of the interactants. The effect of group relatedness and structure on reproductive success of individual female African elephant in TNP was also investigated. Adult female reproductive success was significantly influenced by within- group relatedness and structure. Higher reproductive success (with higher frequency of calf production and survival and more female calves produced) were more evident in the closely related groups than groups with low relatedness, suggesting that females from genetically disrupted groups are less likely to be reproductive than those in closely related groups. The possibility of negative effects of poaching on the subsequent generation of poached adult females and the alternative of a positive demographic response through reduced density was assessed by analysing the demographic patterns of the first generation (F1) females of prime-aged adult female African elephants in TNP using within- group relatedness and size. I also compared vital rate (age of first birth and interbirth interval) responses of first generation (F1) cows from Tarangire (poached) elephants with other females from poached (Northern Luangwa National Park, Zambia) and unpoached (Amboseli National Park, Kenya and Addo Elephant National Park, South Africa) populations. Group relatedness had no significant effect on sex ratio of the F1 cows‟ calves. There was a significant difference between the mean age of first birth and interbirth interval of F1 cows from the two (poached, Tarangire and unpoached, Amboseli National Park) elephant populations, suggesting that elephant populations reduced by poaching to low levels show an increase vigour through release from density constraints. Based on these results, the broader implications of secondary effects of poaching on elephant populations are critically evaluated. Also the importance of understanding the consequences of these effects is highlighted in light of other elephant conservation and management approaches. This understanding is useful in making conservation and management decisions for elephants and other biodiversity.
- Full Text:
- Date Issued: 2011
- Authors: Munishi, Linus Kasian
- Date: 2011
- Subjects: African elephant , Wildlife conservation , Elephants -- Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10711 , http://hdl.handle.net/10948/d1011612 , African elephant , Wildlife conservation , Elephants -- Africa
- Description: Many elephant populations across Africa were or are being devastated by poaching and habitat loss, making population and range size for the species important issues of conservation concern in elephant ranging areas, including Tarangire National Park (TNP). Poaching and/or overhunting are known to have direct effects on the demography of elephant populations. The current understanding of the indirect effects of poaching on the sociality and demography of elephant populations is relatively poor, both at the group and an individual level. In this thesis the importance of genetic relatedness (as influenced by poaching) on sociality and demography of the female elephants was studied, using a combination of genetic, observation of behaviour and two decades of demography data collected from the northern subpopulation of TNP. I investigated and characterized the relatedness categories within elephant groups. Using a conceptual model for group size analysis in aggregation economies, I hypothesized that elephant populations subject to social disruptions due to poaching would exhibit characteristics of the free entry model, whereas more stable, closed populations would better fit the group-controlled model. I present a rare quantitative analysis of genetic relatedness and group size patterns among groups of adult female elephants in two wild populations: one in Tarangire National Park (TNP), Tanzania, and another in Addo Elephant National Park (AENP), South Africa. I demonstrate that the group size in African elephant populations is governed by genetic relatedness, and that poaching/overhunting has a significant influence upon the apparent group formation and size in elephants. I then focused on the effect of relatedness on agonistic interactions between adult females. I hypothesized that individual-based aggressive interactions among adult female African elephants would vary according to degree of kinship, with closely related dyads showing less aggression towards each other in resource-limited environments, thereby leading to indirect fitness benefits for individuals. As predicted, females did not show agonistic interactions to their close kin most often, and the frequency and intensity of aggressive interactions was inversely related to the degree of relatedness of the interactants. The effect of group relatedness and structure on reproductive success of individual female African elephant in TNP was also investigated. Adult female reproductive success was significantly influenced by within- group relatedness and structure. Higher reproductive success (with higher frequency of calf production and survival and more female calves produced) were more evident in the closely related groups than groups with low relatedness, suggesting that females from genetically disrupted groups are less likely to be reproductive than those in closely related groups. The possibility of negative effects of poaching on the subsequent generation of poached adult females and the alternative of a positive demographic response through reduced density was assessed by analysing the demographic patterns of the first generation (F1) females of prime-aged adult female African elephants in TNP using within- group relatedness and size. I also compared vital rate (age of first birth and interbirth interval) responses of first generation (F1) cows from Tarangire (poached) elephants with other females from poached (Northern Luangwa National Park, Zambia) and unpoached (Amboseli National Park, Kenya and Addo Elephant National Park, South Africa) populations. Group relatedness had no significant effect on sex ratio of the F1 cows‟ calves. There was a significant difference between the mean age of first birth and interbirth interval of F1 cows from the two (poached, Tarangire and unpoached, Amboseli National Park) elephant populations, suggesting that elephant populations reduced by poaching to low levels show an increase vigour through release from density constraints. Based on these results, the broader implications of secondary effects of poaching on elephant populations are critically evaluated. Also the importance of understanding the consequences of these effects is highlighted in light of other elephant conservation and management approaches. This understanding is useful in making conservation and management decisions for elephants and other biodiversity.
- Full Text:
- Date Issued: 2011
Trials and triumphs in public office: the life and work of E J N Mabuza
- Authors: Sarimana, Ashley
- Date: 2011
- Subjects: Mabuza, E J (Enos John), 1939- Public officers -- South Africa South Africa -- Politics and government -- 20th century South Africa -- History -- 20th century South Africa -- Social conditions -- 20th century Homelands (South Africa) -- Politics and government -- 20th century Homelands (South Africa) -- History -- 20th century Homelands (South Africa) -- Social conditions -- 20th century Apartheid -- South Africa South Africa -- Race relations Actor-network theory
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3305 , http://hdl.handle.net/10962/d1003093
- Description: Enos John Nganani Mabuza's life and work is used as a case study to highlight the conceptual and methodological theories and challenges in academic biographical writing regarding history, memory and legacies. This thesis answers the question: Who was Mabuza and what is his place or relevance in South Africa's history? We over-simplify and stereotype people because it is convenient. We judge others but there is no saint without a past or a sinner without a future. Mabuza reconciled with the main liberation movements and moved from a maligned position on the political fringes to a respectable one within the emerging black economic elite. History, like reference systems and values is not calcified or static. It is prone to interpretation, adaptation, modification, invention, manipulation, decomposition and re-composition. Bourdieu's habitus-field analysis, theory or logic of practice, notions of capital (symbolic, political, social, cultural and economic) is used together with Latour's actor-network theory as the basis of analysis of the social contracts and trust bonds that Mabuza was able to create and which enabled him to navigate South Africa's socio-political and economic milieus during apartheid and the transition in the early 1990s. As people or actors, we believe in the mantra, nothing ventured, nothing gained. We exercise agency and take risks every day. We make choices and those choices have consequences. Mabuza's choices in the fields of education, politics and business had implications for how he is perceived or has been written into history. His choices put notions of identity, citizenship, power, legitimacy, ambition, elite accommodation, class, personal and professional networks, popular struggles, agency and structure under the spotlight. Mabuza's involvement in Bantustan politics, for instance, is contextualised in terms of a historical overview of the unpopular role played by traditional authorities in South Africa before and during colonialism and apartheid. His later foray into the world of business, however, was facilitated in part, by the personal and professional contacts that he made whilst he was in politics and the opportunities which opened up during the country's political transition. Mabuza adapted to changing circumstances and demonstrated a level of versatility which other Bantustan functionaries did not or could not exercise.
- Full Text:
- Date Issued: 2011
- Authors: Sarimana, Ashley
- Date: 2011
- Subjects: Mabuza, E J (Enos John), 1939- Public officers -- South Africa South Africa -- Politics and government -- 20th century South Africa -- History -- 20th century South Africa -- Social conditions -- 20th century Homelands (South Africa) -- Politics and government -- 20th century Homelands (South Africa) -- History -- 20th century Homelands (South Africa) -- Social conditions -- 20th century Apartheid -- South Africa South Africa -- Race relations Actor-network theory
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3305 , http://hdl.handle.net/10962/d1003093
- Description: Enos John Nganani Mabuza's life and work is used as a case study to highlight the conceptual and methodological theories and challenges in academic biographical writing regarding history, memory and legacies. This thesis answers the question: Who was Mabuza and what is his place or relevance in South Africa's history? We over-simplify and stereotype people because it is convenient. We judge others but there is no saint without a past or a sinner without a future. Mabuza reconciled with the main liberation movements and moved from a maligned position on the political fringes to a respectable one within the emerging black economic elite. History, like reference systems and values is not calcified or static. It is prone to interpretation, adaptation, modification, invention, manipulation, decomposition and re-composition. Bourdieu's habitus-field analysis, theory or logic of practice, notions of capital (symbolic, political, social, cultural and economic) is used together with Latour's actor-network theory as the basis of analysis of the social contracts and trust bonds that Mabuza was able to create and which enabled him to navigate South Africa's socio-political and economic milieus during apartheid and the transition in the early 1990s. As people or actors, we believe in the mantra, nothing ventured, nothing gained. We exercise agency and take risks every day. We make choices and those choices have consequences. Mabuza's choices in the fields of education, politics and business had implications for how he is perceived or has been written into history. His choices put notions of identity, citizenship, power, legitimacy, ambition, elite accommodation, class, personal and professional networks, popular struggles, agency and structure under the spotlight. Mabuza's involvement in Bantustan politics, for instance, is contextualised in terms of a historical overview of the unpopular role played by traditional authorities in South Africa before and during colonialism and apartheid. His later foray into the world of business, however, was facilitated in part, by the personal and professional contacts that he made whilst he was in politics and the opportunities which opened up during the country's political transition. Mabuza adapted to changing circumstances and demonstrated a level of versatility which other Bantustan functionaries did not or could not exercise.
- Full Text:
- Date Issued: 2011
Secondary school children's experiences of bereavement: implications for school counselling in Harare Metropolitan Province
- Authors: Shumba, Jenn
- Date: 2011
- Subjects: Bereavement , Counseling in secondary education -- Zimbabwe -- Harare , Schools -- Zimbabwe -- Harare -- Social conditions , Teachers -- Zimbabwe -- Harare -- Attitudes , Teachers -- Training -- Zimbabwe -- Harare , School children -- Zimbabwe -- Harare
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: vital:16196 , http://hdl.handle.net/10353/d1007237 , Bereavement , Counseling in secondary education -- Zimbabwe -- Harare , Schools -- Zimbabwe -- Harare -- Social conditions , Teachers -- Zimbabwe -- Harare -- Attitudes , Teachers -- Training -- Zimbabwe -- Harare , School children -- Zimbabwe -- Harare
- Description: Death and bereavement are prevalent in Zimbabwe due to HIV/AIDS and other illnesses. It is estimated that a large population of school going learners have lost one or both parents and have become orphans. The aim of the study was two-fold: to understand the bereavement experiences of orphaned learners and to examine how such experiences can inform school counselling services. A multiple case study involving 13 school children and four school counsellors from two secondary schools in Harare Metropolitan Region was conducted. Each of the 17 participants was viewed as a bounded case due to his or her individual unique experiences. An interpretive phenomenological approach was employed to collect and analyse the data. All the cases were purposively selected as they were bearers of crucial information on bereavement experiences and bereavement counselling. The study established nine (9) key findings. First, it was found that the type of attachments and support systems the child had were contributory to the way the child experienced bereavement. Second, it was established that although learners manifested emotional pain, they found it difficult to verbalise it. Third, the study found that cultural practices either exacerbate or work for the better for bereaved children as some were seen to enhance their livelihood whilst some were detrimental and oppressive. Fourth, it was established that bereavement triggered philosophical and reflexive reactions on the part of bereaved children. The deaths of the parents resulted in them reflecting on the three phases of their life trajectories: life before death; at the time of death; and after death. Fifth, it was also established in the study that there was a mismatch in what children and counsellors claimed to be happening in secondary schools pertaining bereavement counselling provisioning. Sixth, the study found that most children did not receive any bereavement counselling in schools. Only three out of the 13 learner cases interviewed in this study had a teacher in the school talk to them about loss of their parents. In some instances, a child’s bereavement was only discovered through the grapevine or when this researcher got to the school. Seventh, it was established that although counsellors were qualified as both teachers and counsellors, they lacked confidence in dealing with sensitive issues such as bereavement. Eighth, the study also found that although there is a lot of death in Zimbabwe the counselling syllabi lacked focus on bereavement counselling. Ninth, it was also discovered that teachers who were not assigned to counselling duties had negative attitudes towards counselling, a matter which has serious consequences for the bereaved learners. Based on the above findings, the study concludes that bereaved children experienced a variety of circumstances that impacted both positively and negatively on their schooling and rendered them in need of bereavement counselling. It also concludes that bereaved learners in selected Harare schools were not receiving adequate bereavement counselling; schools neither had policies nor laid down procedures on bereavement counselling. For further research, the study recommends that there should be research focusing on methodologies designed to access children’s innermost feelings of emotional pain. There should be further research on the nature of the relationship between a child’s bereavement and educational experiences. Studies involving other bereaved populations, such as, children from rural areas and primary school children should be carried out in order to gain insights on how the phenomenon is experienced by different age groups in different contexts. To improve counselling practice in schools, the study recommends that there should be capacity building programmes aimed at assisting teachers to deal with bereavement counselling. School bereavement counselling should explore collaboration with other stakeholders such as peers, care givers and government as well as non-governmental organisations. Above all, the study recommends that schools should be proactive and have school bereavement policies and procedures on bereavement counselling.
- Full Text:
- Date Issued: 2011
- Authors: Shumba, Jenn
- Date: 2011
- Subjects: Bereavement , Counseling in secondary education -- Zimbabwe -- Harare , Schools -- Zimbabwe -- Harare -- Social conditions , Teachers -- Zimbabwe -- Harare -- Attitudes , Teachers -- Training -- Zimbabwe -- Harare , School children -- Zimbabwe -- Harare
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: vital:16196 , http://hdl.handle.net/10353/d1007237 , Bereavement , Counseling in secondary education -- Zimbabwe -- Harare , Schools -- Zimbabwe -- Harare -- Social conditions , Teachers -- Zimbabwe -- Harare -- Attitudes , Teachers -- Training -- Zimbabwe -- Harare , School children -- Zimbabwe -- Harare
- Description: Death and bereavement are prevalent in Zimbabwe due to HIV/AIDS and other illnesses. It is estimated that a large population of school going learners have lost one or both parents and have become orphans. The aim of the study was two-fold: to understand the bereavement experiences of orphaned learners and to examine how such experiences can inform school counselling services. A multiple case study involving 13 school children and four school counsellors from two secondary schools in Harare Metropolitan Region was conducted. Each of the 17 participants was viewed as a bounded case due to his or her individual unique experiences. An interpretive phenomenological approach was employed to collect and analyse the data. All the cases were purposively selected as they were bearers of crucial information on bereavement experiences and bereavement counselling. The study established nine (9) key findings. First, it was found that the type of attachments and support systems the child had were contributory to the way the child experienced bereavement. Second, it was established that although learners manifested emotional pain, they found it difficult to verbalise it. Third, the study found that cultural practices either exacerbate or work for the better for bereaved children as some were seen to enhance their livelihood whilst some were detrimental and oppressive. Fourth, it was established that bereavement triggered philosophical and reflexive reactions on the part of bereaved children. The deaths of the parents resulted in them reflecting on the three phases of their life trajectories: life before death; at the time of death; and after death. Fifth, it was also established in the study that there was a mismatch in what children and counsellors claimed to be happening in secondary schools pertaining bereavement counselling provisioning. Sixth, the study found that most children did not receive any bereavement counselling in schools. Only three out of the 13 learner cases interviewed in this study had a teacher in the school talk to them about loss of their parents. In some instances, a child’s bereavement was only discovered through the grapevine or when this researcher got to the school. Seventh, it was established that although counsellors were qualified as both teachers and counsellors, they lacked confidence in dealing with sensitive issues such as bereavement. Eighth, the study also found that although there is a lot of death in Zimbabwe the counselling syllabi lacked focus on bereavement counselling. Ninth, it was also discovered that teachers who were not assigned to counselling duties had negative attitudes towards counselling, a matter which has serious consequences for the bereaved learners. Based on the above findings, the study concludes that bereaved children experienced a variety of circumstances that impacted both positively and negatively on their schooling and rendered them in need of bereavement counselling. It also concludes that bereaved learners in selected Harare schools were not receiving adequate bereavement counselling; schools neither had policies nor laid down procedures on bereavement counselling. For further research, the study recommends that there should be research focusing on methodologies designed to access children’s innermost feelings of emotional pain. There should be further research on the nature of the relationship between a child’s bereavement and educational experiences. Studies involving other bereaved populations, such as, children from rural areas and primary school children should be carried out in order to gain insights on how the phenomenon is experienced by different age groups in different contexts. To improve counselling practice in schools, the study recommends that there should be capacity building programmes aimed at assisting teachers to deal with bereavement counselling. School bereavement counselling should explore collaboration with other stakeholders such as peers, care givers and government as well as non-governmental organisations. Above all, the study recommends that schools should be proactive and have school bereavement policies and procedures on bereavement counselling.
- Full Text:
- Date Issued: 2011
Enhancing the role of the Kaizen suggestion tool in South African lean automotive companies of the Eastern Cape
- Authors: Adedeji, Adeyemi Charles
- Date: 2011
- Subjects: Lean manufacturing , Manufacturing processes , Production management -- Mathematical models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:8644 , http://hdl.handle.net/10948/d1008157 , Lean manufacturing , Manufacturing processes , Production management -- Mathematical models
- Description: The Toyota manufacturing system, aptly referred to as Lean manufacturing, has received a reasonable appreciation and awareness over the past decade in South African industry. This production phenomenon constitutes an organizational culture that encourages world-class production success through the liberation of factory resources, while employees are empowered and encouraged to contribute ideas for the improvement of processes and products. However, despite lean awareness and the crucial role of employee participation in the suggestion of ideas in world-class organizations, the performance level of lean manufacturing in South African industry is largely devoid of the Kaizen suggestion tool, particularly in the automotive companies of the Eastern Cape. The aim of this research was to proffer appropriate recommendations, improved awareness, understanding and practice for the improvement of the Kaizen suggestion principle in the automotive companies of the Eastern Cape. The research primarily focused on the ‘management/employees’ paradigm within the organisational context. The methodology employed in the study included a thorough review of the relevant literature and a questionnaire, which was developed and administered to both the management and employees of the thirty automotive components suppliers in Eastern Cape. The target companies constituted the units of analyses and therefore provided the opportunity for a detailed investigation of the links between management and employees as well as a submission of ideas for operational and organisational processes as established in the literature review. Epistemologically, the research is objectivist and paradigmically, positivist. However, some qualitative aspects of the data were relevant to the study and, therefore, were used in a complementary manner. The case approach utilized mixed methods by applying a range of data collection techniques and evidence from multiple sources while the sampling technique was sequential, involving both purposive and stratified random sampling. The study reveals the apparent lack of a systematic mechanism for the practice and administration of the Kaizen suggestion tools in most Eastern Cape automotive companies. This demerit is found to have negatively affected maximum employee participation and involvement in organizational decision making within the Province. The study has established a basic level of awareness and understanding among employees / employers relations that the Kaizen suggestion scheme is a vital tool for delivering strategic objectives in the management of decision making and organizational growth. The study strongly advocates the inclusion of employee suggestion systems as part of the organizational process.
- Full Text:
- Date Issued: 2011
- Authors: Adedeji, Adeyemi Charles
- Date: 2011
- Subjects: Lean manufacturing , Manufacturing processes , Production management -- Mathematical models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:8644 , http://hdl.handle.net/10948/d1008157 , Lean manufacturing , Manufacturing processes , Production management -- Mathematical models
- Description: The Toyota manufacturing system, aptly referred to as Lean manufacturing, has received a reasonable appreciation and awareness over the past decade in South African industry. This production phenomenon constitutes an organizational culture that encourages world-class production success through the liberation of factory resources, while employees are empowered and encouraged to contribute ideas for the improvement of processes and products. However, despite lean awareness and the crucial role of employee participation in the suggestion of ideas in world-class organizations, the performance level of lean manufacturing in South African industry is largely devoid of the Kaizen suggestion tool, particularly in the automotive companies of the Eastern Cape. The aim of this research was to proffer appropriate recommendations, improved awareness, understanding and practice for the improvement of the Kaizen suggestion principle in the automotive companies of the Eastern Cape. The research primarily focused on the ‘management/employees’ paradigm within the organisational context. The methodology employed in the study included a thorough review of the relevant literature and a questionnaire, which was developed and administered to both the management and employees of the thirty automotive components suppliers in Eastern Cape. The target companies constituted the units of analyses and therefore provided the opportunity for a detailed investigation of the links between management and employees as well as a submission of ideas for operational and organisational processes as established in the literature review. Epistemologically, the research is objectivist and paradigmically, positivist. However, some qualitative aspects of the data were relevant to the study and, therefore, were used in a complementary manner. The case approach utilized mixed methods by applying a range of data collection techniques and evidence from multiple sources while the sampling technique was sequential, involving both purposive and stratified random sampling. The study reveals the apparent lack of a systematic mechanism for the practice and administration of the Kaizen suggestion tools in most Eastern Cape automotive companies. This demerit is found to have negatively affected maximum employee participation and involvement in organizational decision making within the Province. The study has established a basic level of awareness and understanding among employees / employers relations that the Kaizen suggestion scheme is a vital tool for delivering strategic objectives in the management of decision making and organizational growth. The study strongly advocates the inclusion of employee suggestion systems as part of the organizational process.
- Full Text:
- Date Issued: 2011
Nursing strategies to facilitate self-management in persons living with diabetes mellitus type 2
- Authors: O'Brien Coleen Ann
- Date: 2011
- Subjects: Diabetes -- Treatment , Nurses -- South Africa , Diabetes -- Prevention Popular works
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10019 , http://hdl.handle.net/10948/1627 , Diabetes -- Treatment , Nurses -- South Africa , Diabetes -- Prevention Popular works
- Description: The growing pandemic of diabetes mellitus (DM) is continuing to spread around the world with developing countries being most vulnerable. Diabetes mellitus is the direct cause of 5 percent of deaths worldwide at present, with an expected increase of 50percent in the next 10 years. Diabetes mellitus was virtually unknown in Africa at the start of the 20th century but the incidence is expected to increase by 80 percent by 2025. South African estimates indicate that at present there are up to four million people living with DM in South Africa, with an expected rise of 25 percent by 2020. If DM is not adequately controlled, life-threatening complications ensue, resulting in financial, physical and emotional costs both for people living with the condition and for their families. There is also a great financial burden on the state, both directly due to the cost of providing health care and indirectly due to loss of productivity and a reduced tax base. Global initiatives against DM include the Diabetes Strategy for Africa compiled by the International Diabetes Federation and World Health Organization. There are several forms of DM with Type 2 being the most common with an estimated 95% of cases. Optimal glycaemic control is essential for the management of DM, potentially allowing the course of the disease to be slowed or halted. The previous medical model of management of chronic disease has changed to an empowerment approach where the person living with the condition is a partner in the management process. This is particularly true of DM where all aspects of life are affected by the condition. During Phase One of this study, a qualitative, exploratory, descriptive, contextual approach was utilized to explore and describe the experiences of persons living with DM and of diabetes nurse educators who assist them in Nelson Mandela Bay. During Phase Two, a conceptual framework was created and utilized to develop strategies which professional nurses may use in facilitating self-management by persons living with DM. Persons living with DM experience a definite initial experience on diagnosis of DM but gradually gain an acceptance and acknowledgment of their condition. They have definite views on the concept of self-management and experience both positive and negative factors influencing self-management. They also have definite ideas on how professional nurses may assist them in achieving self-management. These findings were confirmed ii by the experiences of the diabetes nurse educators who formed the second group of participants in this study. The ACE approach to self-management of DM consists of an Action Strategy, a Coordination Strategy and an Education Strategy. The ACE approach makes use of grand and functional strategies implemented on the macro (national), meso (provincial) and micro (local) levels to enable the professional nurse to assist persons living with DM to achieve self-management of their condition. Grand strategies need to be implemented on a macro or meso level to enable the professional nurse to function effectively on a micro level. Assisting the patient has to go beyond merely improving knowledge about the condition but has to include individual goal setting as well as problem solving skills and coping strategies as part of a therapeutic relationship between the professional nurse and the person living with DM. The level of personal responsibility achieved by persons living with DM is affected by the memes which they hold regarding their level of health and their ability to address any barriers to self-management which they may experience. Making use of the process of the therapeutic relationship, the professional nurse is able to positively influence the memes held by persons living with DM and assist them in achieving a greater level of personal responsibility. The therapeutic relationship is potentially influenced by all three of the strategies described above. This study provides insight into the experiences of persons living with DM and of the diabetes nurse educators who assist them in Nelson Mandela Bay. Recommendations regarding the implementation of a National Diabetes Policy on a macro level are made, as well as recommendations for nursing practice, education and research. The strategies which were evaluated by an Expert Panel provide a tool for the professional nurse to use while assisting persons living with DM by facilitating the growth of personal responsibility leading to self-management.
- Full Text:
- Date Issued: 2011
- Authors: O'Brien Coleen Ann
- Date: 2011
- Subjects: Diabetes -- Treatment , Nurses -- South Africa , Diabetes -- Prevention Popular works
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10019 , http://hdl.handle.net/10948/1627 , Diabetes -- Treatment , Nurses -- South Africa , Diabetes -- Prevention Popular works
- Description: The growing pandemic of diabetes mellitus (DM) is continuing to spread around the world with developing countries being most vulnerable. Diabetes mellitus is the direct cause of 5 percent of deaths worldwide at present, with an expected increase of 50percent in the next 10 years. Diabetes mellitus was virtually unknown in Africa at the start of the 20th century but the incidence is expected to increase by 80 percent by 2025. South African estimates indicate that at present there are up to four million people living with DM in South Africa, with an expected rise of 25 percent by 2020. If DM is not adequately controlled, life-threatening complications ensue, resulting in financial, physical and emotional costs both for people living with the condition and for their families. There is also a great financial burden on the state, both directly due to the cost of providing health care and indirectly due to loss of productivity and a reduced tax base. Global initiatives against DM include the Diabetes Strategy for Africa compiled by the International Diabetes Federation and World Health Organization. There are several forms of DM with Type 2 being the most common with an estimated 95% of cases. Optimal glycaemic control is essential for the management of DM, potentially allowing the course of the disease to be slowed or halted. The previous medical model of management of chronic disease has changed to an empowerment approach where the person living with the condition is a partner in the management process. This is particularly true of DM where all aspects of life are affected by the condition. During Phase One of this study, a qualitative, exploratory, descriptive, contextual approach was utilized to explore and describe the experiences of persons living with DM and of diabetes nurse educators who assist them in Nelson Mandela Bay. During Phase Two, a conceptual framework was created and utilized to develop strategies which professional nurses may use in facilitating self-management by persons living with DM. Persons living with DM experience a definite initial experience on diagnosis of DM but gradually gain an acceptance and acknowledgment of their condition. They have definite views on the concept of self-management and experience both positive and negative factors influencing self-management. They also have definite ideas on how professional nurses may assist them in achieving self-management. These findings were confirmed ii by the experiences of the diabetes nurse educators who formed the second group of participants in this study. The ACE approach to self-management of DM consists of an Action Strategy, a Coordination Strategy and an Education Strategy. The ACE approach makes use of grand and functional strategies implemented on the macro (national), meso (provincial) and micro (local) levels to enable the professional nurse to assist persons living with DM to achieve self-management of their condition. Grand strategies need to be implemented on a macro or meso level to enable the professional nurse to function effectively on a micro level. Assisting the patient has to go beyond merely improving knowledge about the condition but has to include individual goal setting as well as problem solving skills and coping strategies as part of a therapeutic relationship between the professional nurse and the person living with DM. The level of personal responsibility achieved by persons living with DM is affected by the memes which they hold regarding their level of health and their ability to address any barriers to self-management which they may experience. Making use of the process of the therapeutic relationship, the professional nurse is able to positively influence the memes held by persons living with DM and assist them in achieving a greater level of personal responsibility. The therapeutic relationship is potentially influenced by all three of the strategies described above. This study provides insight into the experiences of persons living with DM and of the diabetes nurse educators who assist them in Nelson Mandela Bay. Recommendations regarding the implementation of a National Diabetes Policy on a macro level are made, as well as recommendations for nursing practice, education and research. The strategies which were evaluated by an Expert Panel provide a tool for the professional nurse to use while assisting persons living with DM by facilitating the growth of personal responsibility leading to self-management.
- Full Text:
- Date Issued: 2011
The role of the press in political conflicts in Kenya : a case study of the performance of the nation and the East African Standard Newspapers
- Authors: Nyambuga, Charles Ongadi
- Date: 2011
- Subjects: Press and politics -- Kenya , Government and the press -- Kenya , Mass media -- Political aspects , Kenya -- Politics and government
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:16135 , http://hdl.handle.net/10948/1449 , Press and politics -- Kenya , Government and the press -- Kenya , Mass media -- Political aspects , Kenya -- Politics and government
- Description: This study focuses on the role of the press in violent political conflicts in Kenya in the period that preceded the 2005 referendum on the draft constitution. Based on media reports, six major thematic areas of concern emerged during constitution making. These were: land tenure, devolution of power, the executive, the legislature, the Bill of Rights, and the provincial administration. These sections of the draft constitution caused a remarkable divergence of opinion. The citizens either supported or opposed the draft constitution on the basis of how the draft had treated those sections in the draft constitution. Besides the major thematic areas, newspapers regularly focused and reported on ethnicity, violence, political leaders‟ utterances, the process of constitution making, and political conflicts. Three main objectives guided the study. The first objective focused on the relationship between media content and different levels of political conflict. The influence of media content and how these may have led to high political conflict, medium political conflict, low political conflict and no political conflict, are tested in this study. The second objective highlighted the kind of coverage that the draft constitution got during the period that preceded the referendum in November, 2005. This objective facilitated interrogation of media content and whether media content focused on aspects of the draft constitution such as land ownership, the executive, devolution, the legislature and religion, as highlighted in the draft constitution of Kenya 2005. The third objective examined the thematic emphasis that the media undertook in the period that preceded the referendum. The themes that were dominant in the period before the referendum could have impacted on readers' perceptions of the critical issues that could have informed the voters' decisions. Three primary questions were addressed in the study: Firstly, was there a link between media content and different levels of political conflict in weak democracies such as Kenya? Secondly, did media content influence ethnicity and did it encourage ethnic conflict in diverse societies? Finally, what were the key thematic areas of coverage by the press, and how were they used during the referendum? In order to study these research objectives, I used a combination of theories to enhance understanding of the interplay between media content and audience in the society. The theories are: agenda setting, two-step flow, priming, framing, and the public sphere. The study adopts a triangulation convergence design in mixed- methods research that involves both qualitative and quantitative methods. A structured questionnaire and content analysis were used to seek responses to the research questions of the study and to meet the stated objectives. The research revealed that the two newspapers under investigation, namely the East African Standard and the Nation, provided more coverage to issues that were not central to the content of the draft constitution, such as political leaders' utterances, violence, ethnicity, and the process of constitution making. This showed that the newspapers tended to sensationalise issues instead of providing objective coverage of political matters. These newspapers used their opinion pages to educate their readers on how the referendum was turning violent. The theme of political leaders' utterances is closely linked to that of violence. This suggests that the violence was influenced by some of the leaders' statements. These utterances, and more so those that touched on ethnicity, could therefore have been a potential cause of the ensuing political conflicts during the 2005 referendum on the draft constitution. The findings reveal that newspaper editors tended to focus on political conflict at the expense of the actual content of the draft constitution. This would have provided insight and knowledge on the document and avoided sensational reporting, which could have contributed to violent political conflicts during the period that preceded the referendum on the draft constitution of Kenya.
- Full Text:
- Date Issued: 2011
- Authors: Nyambuga, Charles Ongadi
- Date: 2011
- Subjects: Press and politics -- Kenya , Government and the press -- Kenya , Mass media -- Political aspects , Kenya -- Politics and government
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:16135 , http://hdl.handle.net/10948/1449 , Press and politics -- Kenya , Government and the press -- Kenya , Mass media -- Political aspects , Kenya -- Politics and government
- Description: This study focuses on the role of the press in violent political conflicts in Kenya in the period that preceded the 2005 referendum on the draft constitution. Based on media reports, six major thematic areas of concern emerged during constitution making. These were: land tenure, devolution of power, the executive, the legislature, the Bill of Rights, and the provincial administration. These sections of the draft constitution caused a remarkable divergence of opinion. The citizens either supported or opposed the draft constitution on the basis of how the draft had treated those sections in the draft constitution. Besides the major thematic areas, newspapers regularly focused and reported on ethnicity, violence, political leaders‟ utterances, the process of constitution making, and political conflicts. Three main objectives guided the study. The first objective focused on the relationship between media content and different levels of political conflict. The influence of media content and how these may have led to high political conflict, medium political conflict, low political conflict and no political conflict, are tested in this study. The second objective highlighted the kind of coverage that the draft constitution got during the period that preceded the referendum in November, 2005. This objective facilitated interrogation of media content and whether media content focused on aspects of the draft constitution such as land ownership, the executive, devolution, the legislature and religion, as highlighted in the draft constitution of Kenya 2005. The third objective examined the thematic emphasis that the media undertook in the period that preceded the referendum. The themes that were dominant in the period before the referendum could have impacted on readers' perceptions of the critical issues that could have informed the voters' decisions. Three primary questions were addressed in the study: Firstly, was there a link between media content and different levels of political conflict in weak democracies such as Kenya? Secondly, did media content influence ethnicity and did it encourage ethnic conflict in diverse societies? Finally, what were the key thematic areas of coverage by the press, and how were they used during the referendum? In order to study these research objectives, I used a combination of theories to enhance understanding of the interplay between media content and audience in the society. The theories are: agenda setting, two-step flow, priming, framing, and the public sphere. The study adopts a triangulation convergence design in mixed- methods research that involves both qualitative and quantitative methods. A structured questionnaire and content analysis were used to seek responses to the research questions of the study and to meet the stated objectives. The research revealed that the two newspapers under investigation, namely the East African Standard and the Nation, provided more coverage to issues that were not central to the content of the draft constitution, such as political leaders' utterances, violence, ethnicity, and the process of constitution making. This showed that the newspapers tended to sensationalise issues instead of providing objective coverage of political matters. These newspapers used their opinion pages to educate their readers on how the referendum was turning violent. The theme of political leaders' utterances is closely linked to that of violence. This suggests that the violence was influenced by some of the leaders' statements. These utterances, and more so those that touched on ethnicity, could therefore have been a potential cause of the ensuing political conflicts during the 2005 referendum on the draft constitution. The findings reveal that newspaper editors tended to focus on political conflict at the expense of the actual content of the draft constitution. This would have provided insight and knowledge on the document and avoided sensational reporting, which could have contributed to violent political conflicts during the period that preceded the referendum on the draft constitution of Kenya.
- Full Text:
- Date Issued: 2011
Identity, belonging and ecological crisis in South African speculative fiction
- Authors: Steenkamp, Elzette Lorna
- Date: 2011
- Subjects: South African fiction -- History and criticism Identity (Philosophical concept) in literature Group identity in literature Ecology in literature Science fiction, South African -- History and criticism Fantasy fiction, South African -- History and criticism Ecofiction -- History and criticism Ecocriticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2219 , http://hdl.handle.net/10962/d1002262
- Description: This study examines a range of South African speculative novels which situate their narratives in futuristic or ‘alternative’ milieus, exploring how these narratives not only address identity formation in a deeply divided and rapidly changing society, but also the ways in which human beings place themselves in relation to Nature and form notions of ‘ecological’ belonging. It offers close readings of these speculative narratives in order to investigate the ways in which they evince concerns which are rooted in the natural, social and political landscapes which inform them. Specific attention is paid to the texts’ treatment of the intertwined issues of identity, belonging and ecological crisis. This dissertation draws on the fields of Ecocriticism, Postcolonial Studies and Science Fiction Studies, and assumes a culturally specific approach to primary texts while investigating possible cross-cultural commonalities between Afrikaans and English speculative narratives, as well as the cross-fertilisation of global SF/speculative features. It is suggested that South African speculative fiction presents a socio-historically situated, rhizomatic approach to ecology – one that is attuned to the tension between humanistic- and ecological concerns.
- Full Text:
- Date Issued: 2011
- Authors: Steenkamp, Elzette Lorna
- Date: 2011
- Subjects: South African fiction -- History and criticism Identity (Philosophical concept) in literature Group identity in literature Ecology in literature Science fiction, South African -- History and criticism Fantasy fiction, South African -- History and criticism Ecofiction -- History and criticism Ecocriticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2219 , http://hdl.handle.net/10962/d1002262
- Description: This study examines a range of South African speculative novels which situate their narratives in futuristic or ‘alternative’ milieus, exploring how these narratives not only address identity formation in a deeply divided and rapidly changing society, but also the ways in which human beings place themselves in relation to Nature and form notions of ‘ecological’ belonging. It offers close readings of these speculative narratives in order to investigate the ways in which they evince concerns which are rooted in the natural, social and political landscapes which inform them. Specific attention is paid to the texts’ treatment of the intertwined issues of identity, belonging and ecological crisis. This dissertation draws on the fields of Ecocriticism, Postcolonial Studies and Science Fiction Studies, and assumes a culturally specific approach to primary texts while investigating possible cross-cultural commonalities between Afrikaans and English speculative narratives, as well as the cross-fertilisation of global SF/speculative features. It is suggested that South African speculative fiction presents a socio-historically situated, rhizomatic approach to ecology – one that is attuned to the tension between humanistic- and ecological concerns.
- Full Text:
- Date Issued: 2011
Comparative study of the feeding damage caused by the South African biotypes of the Russian wheat aphid (Diuraphis noxia Kurdjumov) on resistant and non-resistant lines of barley (Hordeum vulgare L.)
- Authors: Jimoh, Mahboob Adekilekun
- Date: 2011
- Subjects: Aphids Russian wheat aphid -- Research -- South Africa Barley -- Diseases and pests -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4201 , http://hdl.handle.net/10962/d1003770
- Description: Cereal crop productivity is hampered when these plants are infested by phloem feeding aphids. A great deal of research has been carried out with the direct aim of a clearer understanding of the mechanism involved in the interaction between aphids and their host plants. Research has directly or indirectly been geared towards enhanced plant productivity and achieving sustainable agriculture. Barley (Hordeum vulgare L.) is an important small grain crop in South Africa, whose crop performance is negatively affected by fluctuations in weather patterns as well as by agricultural pests. One of the insect pests infesting barley is the Russian wheat aphid, Diuraphis noxia Kurdjumov (RWA), of which the two South African biotypes, codenamed RWASA1 and RWASA2, were studied in this thesis. During dry spells, RWA infestation becomes a more serious threat to barley productivity. Resistant plants have been used to combat RWA infestation of small grains. In South Africa, 27 RWA-resistant wheat cultivars are currently used in commercial cultivation, but no resistant barley lines have, unfortunately, been developed, in spite of this grain’s significant economic importance. This informed the study in this thesis, and this interest particularly focussed on three RWA-resistant lines developed by the USDA, testing their performance against South African RWA biotypes, for possible adaptation to South Africa. The aim was thus to examine the plant-aphid interactions, aphid breeding rates, plant damage and sustainability, evidence of resistance or tolerance and finally potential performance under elevated CO2 (a very real climate change threat). Two major avenues of research were undertaken. The first aspect involved examination of structural and functional damage caused by RWASA1 and RWASA2 on the three resistant and a non-resistant line. Aphid population growth and damage symptoms (chlorosis and leaf roll) of infestation by these aphid biotypes were evaluated. This was followed by a structural and functional approach in which the effects of feeding on the transport systems (phloem and xylem) of barley were investigated. Fluorescence microscopy techniques (using aniline blue fluorochrome, a specific stain for callose and 5,6-CFDA, a phloem-mobile probe) were applied to investigate the feeding-related damage caused by the aphids, through an examination of wound callose formation and related to this, the resultant reduction in phloem transport capacity. Transmission electron microscopy (TEM) techniques provided evidence of the extent of the feeding-related cell damage. The second aspect involved a study of the effect of changing CO2 concentrations ([CO2]) on the resistant and susceptible barley cultivars to feeding by the two RWA biotypes. Leaves of plants grown at ambient and two elevated levels of [CO2] were analysed to investigate the effect of changing [CO2] on biomass, leaf nitrogen content and C:N ratio of control (uninfested) and infested plants. The population growth studies showed that the populations of the two RWA biotypes as well as bird cherry-oat aphid (BCA, Rhopalosiphum padi L.) increased substantially on the four barley lines. BCA was included here, as it had been the subject of several previous studies. RWASA2 bred faster than RWASA1 on all lines. The breeding rates of the two RWA biotypes were both suppressed and at near-equivalent levels on the three resistant lines, compared to the non-resistant PUMA. This suggests that the resistant lines possessed an antibiosis resistance mechanism against the feeding aphids. Feeding by the aphids manifested in morphological damage symptoms of chlorosis and leaf roll. The two biotypes inflicted severe chlorosis and leaf roll on the non-resistant PUMA. In the resistant plants, leaf rolling was more severe because of RWASA2 feeding compared to RWASA1 feeding. In contrast, chlorosis symptoms were more severe during RWASA1 feeding than was the case with RWASA2 feeding. Investigation of the effect of aphid feeding on the plants showed that callose was deposited within 24h and that this increased with longer feeding exposure. Wound callose distribution is more extensive in the non-resistant PUMA than in the resistant plants. RWASA2 feeding on the resistant lines caused deposition of more callose than was evident with RWASA1 feeding. During long-term feeding, it was evident that variation in the intensity and amount of wound callose was visible in the longitudinal and transverse veins of the resistant plants. Of the three STARS plants, STARS-9301B had the least callose. Interestingly, wound callose occurred in both resistant and non-resistant plants, in sharp contrast to what has been reported on resistant wheat cultivars that were developed in South Africa. The relative reduction in the wound callose deposited in the resistant line, when compared to the non-resistant lines, suggests the presence of a mechanism in the resistant lines, which may prevent excessive callose formation. Alternatively, the mechanism may stimulate callose breakdown. RWASA2 feeding on the resistant lines deposited more wound callose than RWASA1 feeding. This evidence supports the hypothesis that RWASA2 is a resistance breaking and more aggressive feeder than RWASA1 is; and further underscores the urgent need for development of RWA-resistant barley cultivars. The ultrastructural investigation of the feeding damage showed that the two biotypes caused extensive vascular damage in non-resistant plants. There was extensive and severe cell disruption and often obliteration of cell structure of the vascular parenchyma, xylem and phloem elements. In sharp contrast, among the resistant plants, feeding-related cell damage appeared to be substantially reduced compared to the non-resistant PUMA. Low frequency of damaged cells indicated that majority of the cell components of the vascular tissues were intact and presumed functional. There was evidence of salivary material lining the secondary walls of the vascular tissue, which resulted in severe damage. Within xylem vessels, saliva material impregnated half-bordered pit pairs between the vessels and adjacent xylem parenchyma. This is believed to prevent solute exchange through this interface, thereby inducing leaf stress and vi leaf roll. A notable finding is that RWASA2 effectively induced more cell damage to vascular tissues in the resistant lines than did RWASA1. In general the experimental evidence (see Chapter 5) suggests that the resistant lines are possibly more tolerant (or able to cope with) to RWA feeding. Evidence for this is the reduction of wound callose and at the TEM level, a comparatively less obvious cell damage in the resistant lines, which suggests that they possess antibiosis and tolerance capacity. The apparent reduction of feeding-related cell damage from the TEM study confirmed the disruptive action of the feeding aphids in experiments using the phloem-mobile probe, 5,6-CF. Results showed that feeding by RWASA1 and RWASA2 reducedthe transport functionality of the phloem in all cases, but that RWASA2 feeding caused a more obvious reduction in the rate and distance that 5,6-carboxyfluorescein was transported, than did RWASA1. Investigation of the effect of changing [CO2] on the barley cultivars showed that in the absence of aphids and under elevated CO2 conditions, the plants grew more vigorously. In this series of experiments, the infested plants suffered significant reduction in biomass under ambient (as was expected) and under the two elevated CO2 regimes. Biomass loss was greater at elevated CO2 than under ambient [CO2]. The infested nonresistant PUMA plants showed a more significant biomass loss than did the resistant cultivars. Clearly, the benefits derived from elevated CO2 enrichment was thus redirected to the now-advantaged aphids. Uninfested vii plants showed an increase in leaf nitrogen under the experimental conditions. However, feeding aphids depleted leaf nitrogen content and this was more apparent on plants exposed to RWASA2 than was the case with RWASA1. The end result of this was that C:N ratio of infested plants were higher than uninfested plants. Clearly, the faster breeding rates of the aphids at elevated CO2 caused depletion of N and a resultant deficiency exacerbated chlorosis as well as leaf rolling due to the higher aphid population density under elevated CO2 than at ambient. By 28 days after infestation (DAI), majority of the plants exposed to enriched CO2 treatments had died. A major finding here was thus that although this study demonstrated that elevated CO2 resulted in an increase in biomass, this was detrimentally offset in plants infested by the aphids, with a decline in biomass and loss of functionality leading to plant death at 28DAI. The overriding conclusion from this study is a clear signal that the twin effects of CO2 enrichment (a feature of current climate change) and aphid infestations may precipitate potential grain shortages. A disastrous food security threat looms.
- Full Text:
- Date Issued: 2011
- Authors: Jimoh, Mahboob Adekilekun
- Date: 2011
- Subjects: Aphids Russian wheat aphid -- Research -- South Africa Barley -- Diseases and pests -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4201 , http://hdl.handle.net/10962/d1003770
- Description: Cereal crop productivity is hampered when these plants are infested by phloem feeding aphids. A great deal of research has been carried out with the direct aim of a clearer understanding of the mechanism involved in the interaction between aphids and their host plants. Research has directly or indirectly been geared towards enhanced plant productivity and achieving sustainable agriculture. Barley (Hordeum vulgare L.) is an important small grain crop in South Africa, whose crop performance is negatively affected by fluctuations in weather patterns as well as by agricultural pests. One of the insect pests infesting barley is the Russian wheat aphid, Diuraphis noxia Kurdjumov (RWA), of which the two South African biotypes, codenamed RWASA1 and RWASA2, were studied in this thesis. During dry spells, RWA infestation becomes a more serious threat to barley productivity. Resistant plants have been used to combat RWA infestation of small grains. In South Africa, 27 RWA-resistant wheat cultivars are currently used in commercial cultivation, but no resistant barley lines have, unfortunately, been developed, in spite of this grain’s significant economic importance. This informed the study in this thesis, and this interest particularly focussed on three RWA-resistant lines developed by the USDA, testing their performance against South African RWA biotypes, for possible adaptation to South Africa. The aim was thus to examine the plant-aphid interactions, aphid breeding rates, plant damage and sustainability, evidence of resistance or tolerance and finally potential performance under elevated CO2 (a very real climate change threat). Two major avenues of research were undertaken. The first aspect involved examination of structural and functional damage caused by RWASA1 and RWASA2 on the three resistant and a non-resistant line. Aphid population growth and damage symptoms (chlorosis and leaf roll) of infestation by these aphid biotypes were evaluated. This was followed by a structural and functional approach in which the effects of feeding on the transport systems (phloem and xylem) of barley were investigated. Fluorescence microscopy techniques (using aniline blue fluorochrome, a specific stain for callose and 5,6-CFDA, a phloem-mobile probe) were applied to investigate the feeding-related damage caused by the aphids, through an examination of wound callose formation and related to this, the resultant reduction in phloem transport capacity. Transmission electron microscopy (TEM) techniques provided evidence of the extent of the feeding-related cell damage. The second aspect involved a study of the effect of changing CO2 concentrations ([CO2]) on the resistant and susceptible barley cultivars to feeding by the two RWA biotypes. Leaves of plants grown at ambient and two elevated levels of [CO2] were analysed to investigate the effect of changing [CO2] on biomass, leaf nitrogen content and C:N ratio of control (uninfested) and infested plants. The population growth studies showed that the populations of the two RWA biotypes as well as bird cherry-oat aphid (BCA, Rhopalosiphum padi L.) increased substantially on the four barley lines. BCA was included here, as it had been the subject of several previous studies. RWASA2 bred faster than RWASA1 on all lines. The breeding rates of the two RWA biotypes were both suppressed and at near-equivalent levels on the three resistant lines, compared to the non-resistant PUMA. This suggests that the resistant lines possessed an antibiosis resistance mechanism against the feeding aphids. Feeding by the aphids manifested in morphological damage symptoms of chlorosis and leaf roll. The two biotypes inflicted severe chlorosis and leaf roll on the non-resistant PUMA. In the resistant plants, leaf rolling was more severe because of RWASA2 feeding compared to RWASA1 feeding. In contrast, chlorosis symptoms were more severe during RWASA1 feeding than was the case with RWASA2 feeding. Investigation of the effect of aphid feeding on the plants showed that callose was deposited within 24h and that this increased with longer feeding exposure. Wound callose distribution is more extensive in the non-resistant PUMA than in the resistant plants. RWASA2 feeding on the resistant lines caused deposition of more callose than was evident with RWASA1 feeding. During long-term feeding, it was evident that variation in the intensity and amount of wound callose was visible in the longitudinal and transverse veins of the resistant plants. Of the three STARS plants, STARS-9301B had the least callose. Interestingly, wound callose occurred in both resistant and non-resistant plants, in sharp contrast to what has been reported on resistant wheat cultivars that were developed in South Africa. The relative reduction in the wound callose deposited in the resistant line, when compared to the non-resistant lines, suggests the presence of a mechanism in the resistant lines, which may prevent excessive callose formation. Alternatively, the mechanism may stimulate callose breakdown. RWASA2 feeding on the resistant lines deposited more wound callose than RWASA1 feeding. This evidence supports the hypothesis that RWASA2 is a resistance breaking and more aggressive feeder than RWASA1 is; and further underscores the urgent need for development of RWA-resistant barley cultivars. The ultrastructural investigation of the feeding damage showed that the two biotypes caused extensive vascular damage in non-resistant plants. There was extensive and severe cell disruption and often obliteration of cell structure of the vascular parenchyma, xylem and phloem elements. In sharp contrast, among the resistant plants, feeding-related cell damage appeared to be substantially reduced compared to the non-resistant PUMA. Low frequency of damaged cells indicated that majority of the cell components of the vascular tissues were intact and presumed functional. There was evidence of salivary material lining the secondary walls of the vascular tissue, which resulted in severe damage. Within xylem vessels, saliva material impregnated half-bordered pit pairs between the vessels and adjacent xylem parenchyma. This is believed to prevent solute exchange through this interface, thereby inducing leaf stress and vi leaf roll. A notable finding is that RWASA2 effectively induced more cell damage to vascular tissues in the resistant lines than did RWASA1. In general the experimental evidence (see Chapter 5) suggests that the resistant lines are possibly more tolerant (or able to cope with) to RWA feeding. Evidence for this is the reduction of wound callose and at the TEM level, a comparatively less obvious cell damage in the resistant lines, which suggests that they possess antibiosis and tolerance capacity. The apparent reduction of feeding-related cell damage from the TEM study confirmed the disruptive action of the feeding aphids in experiments using the phloem-mobile probe, 5,6-CF. Results showed that feeding by RWASA1 and RWASA2 reducedthe transport functionality of the phloem in all cases, but that RWASA2 feeding caused a more obvious reduction in the rate and distance that 5,6-carboxyfluorescein was transported, than did RWASA1. Investigation of the effect of changing [CO2] on the barley cultivars showed that in the absence of aphids and under elevated CO2 conditions, the plants grew more vigorously. In this series of experiments, the infested plants suffered significant reduction in biomass under ambient (as was expected) and under the two elevated CO2 regimes. Biomass loss was greater at elevated CO2 than under ambient [CO2]. The infested nonresistant PUMA plants showed a more significant biomass loss than did the resistant cultivars. Clearly, the benefits derived from elevated CO2 enrichment was thus redirected to the now-advantaged aphids. Uninfested vii plants showed an increase in leaf nitrogen under the experimental conditions. However, feeding aphids depleted leaf nitrogen content and this was more apparent on plants exposed to RWASA2 than was the case with RWASA1. The end result of this was that C:N ratio of infested plants were higher than uninfested plants. Clearly, the faster breeding rates of the aphids at elevated CO2 caused depletion of N and a resultant deficiency exacerbated chlorosis as well as leaf rolling due to the higher aphid population density under elevated CO2 than at ambient. By 28 days after infestation (DAI), majority of the plants exposed to enriched CO2 treatments had died. A major finding here was thus that although this study demonstrated that elevated CO2 resulted in an increase in biomass, this was detrimentally offset in plants infested by the aphids, with a decline in biomass and loss of functionality leading to plant death at 28DAI. The overriding conclusion from this study is a clear signal that the twin effects of CO2 enrichment (a feature of current climate change) and aphid infestations may precipitate potential grain shortages. A disastrous food security threat looms.
- Full Text:
- Date Issued: 2011
Relations of family and school attachment to forms of learner violence in secondary school communities in Amathole education district, Eastern Cape
- Authors: Ncube, Thembinkosi
- Date: 2011
- Subjects: School violence -- South Africa -- Eastern Cape , School discipline -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: vital:16166 , http://hdl.handle.net/10353/504 , School violence -- South Africa -- Eastern Cape , School discipline -- South Africa -- Eastern Cape
- Description: Adolescents in the schools in South Africa have been victims of many social problems such as violence and crime as a result of background influence. They have been both victims and perpetrators of this violence. Problems of attachment to both school and home have always been blamed for the adolescents’ deviance. South African schools are affected by this verbal and physical violence which presumably emanates from learners poor connections with school and home. The background of societies such as economic deprivation has also been presumed to have an impact on the way adolescents conduct themselves in schools. There is no research that has verified the correlation between violence and attachment to bases of attachment - home and school in South Africa, especially in the Eastern Cape Province. A survey was conducted in more than ten schools in the Amathole District where 317 learners’ opinions on their observation of cases of verbal and physical violence in their schools, and on their attachment to both home and school were collected through a 40 item questionnaire. The questionnaire had five sections (a) to (e). The first section (a) required learners to enter their biographical information; gender, age, grade, and quintile classification. The second section (b) required learners to rate their attachment to their homes and to their care givers. The third section (c) required learners to rate their connectedness to their schools. The fourth section (d) required learners to supply information on their observation and involvement in verbal violence. The final section (e) with items adopted from section (d) and customised required learners to rate their observation and involvement in physical violence. Descriptive statistics were used to glean frequencies and the overall levels of attachment and violence amongst learners. The study also looked at significant differences in attachment (both family and school) and violence (both verbal and physical) using gender and socio-economic profiles of the learners and schools (quintile system) as sorting or categorising variables. One major finding which is contrary to most theory and may be as a result of social dynamics is that statistics suggested that gender and socio-economic variables had little bearing on violence and attachment. Through the use of SPSS, the Spearman’s rho correlation coefficients were calculated to answer the sub-questions on the relationship between family and school attachment, and school violence (both verbal and physical). There were notable negative and positive correlations between school attachment and verbal violence; for example there was a positive correlation between teachers making learners hate school and learner-involvement in swearing. There was also a negative correlation between school buildings making learners proud and schools and homes being to blame for the frequency of verbal violence in the schools. There were also notable correlations between attachment to family and verbal violence such as the correlation between the frustration by parents’ lack of concern and learners’ involvement in verbal violence without any clear reason. With regard to physical violence there was a negative correlation between parents having time to discuss life with their children and the frequency of physical violence in the schools. There was however a negative correlation between one’s pride in one’s school and the blame on schools for instigating school violence. From these correlations implications for school violence prevention could be drawn. The study reveals that a lot needs to be done by the schools, parents, the government, and the community to enhance learner attachment to both school and home. However, for all the stake holders to succeed government must take the leading role in speeding up the process of reducing poverty in the communities. This is premised on the fact that some findings reveal that frequency of violence increases in an environment of frustration and anger. Schools as care-givers can also introduce many interventions such as counselling workshops to equip teachers with professional crisis management. The research may encourage the Department of Education and schools to adopt violence prevention programs implemented in countries (like United States of America’s Olweus bullying and violence prevention program) for use in bringing communities together to work against school violence. These findings might strengthen the South African Department of Education’s Safe Schools Programs.
- Full Text:
- Date Issued: 2011
- Authors: Ncube, Thembinkosi
- Date: 2011
- Subjects: School violence -- South Africa -- Eastern Cape , School discipline -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: vital:16166 , http://hdl.handle.net/10353/504 , School violence -- South Africa -- Eastern Cape , School discipline -- South Africa -- Eastern Cape
- Description: Adolescents in the schools in South Africa have been victims of many social problems such as violence and crime as a result of background influence. They have been both victims and perpetrators of this violence. Problems of attachment to both school and home have always been blamed for the adolescents’ deviance. South African schools are affected by this verbal and physical violence which presumably emanates from learners poor connections with school and home. The background of societies such as economic deprivation has also been presumed to have an impact on the way adolescents conduct themselves in schools. There is no research that has verified the correlation between violence and attachment to bases of attachment - home and school in South Africa, especially in the Eastern Cape Province. A survey was conducted in more than ten schools in the Amathole District where 317 learners’ opinions on their observation of cases of verbal and physical violence in their schools, and on their attachment to both home and school were collected through a 40 item questionnaire. The questionnaire had five sections (a) to (e). The first section (a) required learners to enter their biographical information; gender, age, grade, and quintile classification. The second section (b) required learners to rate their attachment to their homes and to their care givers. The third section (c) required learners to rate their connectedness to their schools. The fourth section (d) required learners to supply information on their observation and involvement in verbal violence. The final section (e) with items adopted from section (d) and customised required learners to rate their observation and involvement in physical violence. Descriptive statistics were used to glean frequencies and the overall levels of attachment and violence amongst learners. The study also looked at significant differences in attachment (both family and school) and violence (both verbal and physical) using gender and socio-economic profiles of the learners and schools (quintile system) as sorting or categorising variables. One major finding which is contrary to most theory and may be as a result of social dynamics is that statistics suggested that gender and socio-economic variables had little bearing on violence and attachment. Through the use of SPSS, the Spearman’s rho correlation coefficients were calculated to answer the sub-questions on the relationship between family and school attachment, and school violence (both verbal and physical). There were notable negative and positive correlations between school attachment and verbal violence; for example there was a positive correlation between teachers making learners hate school and learner-involvement in swearing. There was also a negative correlation between school buildings making learners proud and schools and homes being to blame for the frequency of verbal violence in the schools. There were also notable correlations between attachment to family and verbal violence such as the correlation between the frustration by parents’ lack of concern and learners’ involvement in verbal violence without any clear reason. With regard to physical violence there was a negative correlation between parents having time to discuss life with their children and the frequency of physical violence in the schools. There was however a negative correlation between one’s pride in one’s school and the blame on schools for instigating school violence. From these correlations implications for school violence prevention could be drawn. The study reveals that a lot needs to be done by the schools, parents, the government, and the community to enhance learner attachment to both school and home. However, for all the stake holders to succeed government must take the leading role in speeding up the process of reducing poverty in the communities. This is premised on the fact that some findings reveal that frequency of violence increases in an environment of frustration and anger. Schools as care-givers can also introduce many interventions such as counselling workshops to equip teachers with professional crisis management. The research may encourage the Department of Education and schools to adopt violence prevention programs implemented in countries (like United States of America’s Olweus bullying and violence prevention program) for use in bringing communities together to work against school violence. These findings might strengthen the South African Department of Education’s Safe Schools Programs.
- Full Text:
- Date Issued: 2011
Trust building strategies to enhance collective bargaining processes in organisations
- Authors: Ngalo, Osmond Tolo
- Date: 2011
- Subjects: Trust , Collective bargaining
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9398 , http://hdl.handle.net/10948/1312 , Trust , Collective bargaining
- Description: The main research problem in this study was to identify what trust-building strategies can be utilised by organisations to enhance collective bargaining processes. To achieve this objective a theoretical Institutional Arrangements-Based Model of trust-building was conceptualised, developed and presented in Chapter 5. The presentation of this model was the culmination of the research design phases outlined below: -The first phase consisted of a literature survey undertaken to discover the nature and dynamics of the concept "trust". -The second phase consisted of surveying the literature attempting to understand the nature of the collective bargaining process, its elements and types and the environmental factors that tend to impinge on it. -The final phase of the literature survey focused on various trust-building strategies, theories and models that can be utilised by organisations to ii enhance collective bargaining processes. Trust is generally acknowledged as a necessary requirement for effective and successful workplace relationships. Because of this factor it is crucial that South African employer-employee relationships are improved in a conscious and sustainable way in order for our businesses to remain competitive in the face of global competition. With this reality in mind there is still much in the South African labour relations environment that fosters conflict. One of the primary factors that impinge on trust in employer-employee relations in South Africa is the previous government‘s divisive and racist apartheid policies. These policies have resulted in serious structural imbalances in the economy, the skewed distribution of wealth and the general scarcity of resources to address these attendant challenges. Finnemore and van Rensburg (2002, p. 36) surveys the current labour relations scenario and comments about the extent to which it has been severely affected by apartheid. Some of its appalling outcomes are: racial divisions between skilled and unskilled workers, apartheid wage gaps, poorly educated workers, dictatorial management styles and a lack of protection for the most vulnerable workers. As revealed in this research study there are still widely divergent views at the workplace regarding the nature and levels of trust that are prevalent. The overwhelming view, however, is that there is, generally, a lack of trust between managerial and employee collective bargaining teams. This lack of trust which is evident between employer and employee parties will tend to result in collective bargaining processes being embarked upon in a climate imbued with the negative spirit of distrust. The recommended Institutional Arrangements-Based Model of trust-building advocates for a process of trust-building prior to any collective bargaining initiatives. This process, as depicted in the elements of the recommended model, needs to begin with phases which will focus on frame-alignment and the identification of all sources of distrust between the parties. These prescribed sessions seek to culminate in a common understanding, between the contesting parties, of their real divergent issues and concerns as well as their existing commonalities. The next phases of the recommended model entail the parties, jointly, developing proposals and policies that in the short and long term will aim at the resolution of the identified sources of distrust and thereby reduce the psychological distance between them. The final phase of the model entails the implementation of joint problem–solving resolutions and the development of appropriate policies i.e. institutional arrangements, to deal with all conflict-prone areas of the business operations. Simultaneously, there needs to be continuous evaluation and monitoring of organisational trust and the "agreed to" trust-building strategies to ensure that distrust is reduced or eliminated in the long term, allowing the organisation and the individual employees to perform at their optimum in order to achieve their common goals.
- Full Text:
- Date Issued: 2011
- Authors: Ngalo, Osmond Tolo
- Date: 2011
- Subjects: Trust , Collective bargaining
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9398 , http://hdl.handle.net/10948/1312 , Trust , Collective bargaining
- Description: The main research problem in this study was to identify what trust-building strategies can be utilised by organisations to enhance collective bargaining processes. To achieve this objective a theoretical Institutional Arrangements-Based Model of trust-building was conceptualised, developed and presented in Chapter 5. The presentation of this model was the culmination of the research design phases outlined below: -The first phase consisted of a literature survey undertaken to discover the nature and dynamics of the concept "trust". -The second phase consisted of surveying the literature attempting to understand the nature of the collective bargaining process, its elements and types and the environmental factors that tend to impinge on it. -The final phase of the literature survey focused on various trust-building strategies, theories and models that can be utilised by organisations to ii enhance collective bargaining processes. Trust is generally acknowledged as a necessary requirement for effective and successful workplace relationships. Because of this factor it is crucial that South African employer-employee relationships are improved in a conscious and sustainable way in order for our businesses to remain competitive in the face of global competition. With this reality in mind there is still much in the South African labour relations environment that fosters conflict. One of the primary factors that impinge on trust in employer-employee relations in South Africa is the previous government‘s divisive and racist apartheid policies. These policies have resulted in serious structural imbalances in the economy, the skewed distribution of wealth and the general scarcity of resources to address these attendant challenges. Finnemore and van Rensburg (2002, p. 36) surveys the current labour relations scenario and comments about the extent to which it has been severely affected by apartheid. Some of its appalling outcomes are: racial divisions between skilled and unskilled workers, apartheid wage gaps, poorly educated workers, dictatorial management styles and a lack of protection for the most vulnerable workers. As revealed in this research study there are still widely divergent views at the workplace regarding the nature and levels of trust that are prevalent. The overwhelming view, however, is that there is, generally, a lack of trust between managerial and employee collective bargaining teams. This lack of trust which is evident between employer and employee parties will tend to result in collective bargaining processes being embarked upon in a climate imbued with the negative spirit of distrust. The recommended Institutional Arrangements-Based Model of trust-building advocates for a process of trust-building prior to any collective bargaining initiatives. This process, as depicted in the elements of the recommended model, needs to begin with phases which will focus on frame-alignment and the identification of all sources of distrust between the parties. These prescribed sessions seek to culminate in a common understanding, between the contesting parties, of their real divergent issues and concerns as well as their existing commonalities. The next phases of the recommended model entail the parties, jointly, developing proposals and policies that in the short and long term will aim at the resolution of the identified sources of distrust and thereby reduce the psychological distance between them. The final phase of the model entails the implementation of joint problem–solving resolutions and the development of appropriate policies i.e. institutional arrangements, to deal with all conflict-prone areas of the business operations. Simultaneously, there needs to be continuous evaluation and monitoring of organisational trust and the "agreed to" trust-building strategies to ensure that distrust is reduced or eliminated in the long term, allowing the organisation and the individual employees to perform at their optimum in order to achieve their common goals.
- Full Text:
- Date Issued: 2011
Sedimentology of plio-pleistocene gravel barrier deposits in the palaeo-Orange River mouth, Namibia : depositional history and diamond mineralisation
- Authors: Spaggiari, Renato Igino
- Date: 2011 , 2013-08-19
- Subjects: Diamond mines and mining -- Namibia Sediments (Geology) -- South Africa and Namibia -- Orange River Estuary Diamond deposits -- Namibia Orange River Estuary (Namibia and South Africa)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4927 , http://hdl.handle.net/10962/d1004636
- Description: The largest known marine diamond placer, the Namibian mega-placer, lies along the Atlantic coast of south-western Africa from the Orange River mouth 1,000 km northwards to the Namibian-Angolan border. The most economically viable portion of the Namibian mega-placer (>75 million carats recovered at >95% gem quality) comprises onshore and offshore marine deposits that are developed within ∼100km of the Orange River outfall. For much of the Cainozoic, this long-lived fluvial system has been the main conduit transporting diamonds from kimberlitic and secondary sources in the cratonic hinterland of southern Africa to the Atlantic shelf that has been neutrally buoyant over this period. Highly energetic marine processes, driven in part, by southerly winds with an attendant northward-directed longshore drift, have generated terminal placers that are preserved both onshore and offshore. This study, through detailed field sedimentological and diamond analyses, investigates the development and mineralisation of gravel barrier deposits within the ancestral Orange River mouth area during a major ∼30 m regional transgression ('30 m Package') in the Late Pliocene. At that time, diamond supply from this fluvial conduit was minimal, yet the corresponding onshore marine deposits to the north of the Orange River mouth were significantly diamond enriched, enabling large-scale alluvial diamond mining to take place for over 75 years. Of the entire coastline of south-western Africa, the most complete accumulation of the '30 m Package' is preserved within the palaeo-Orange River mouth as barrier spit and barrier beach deposits. Arranged vertically and laterally in a 16m thick succession, these are deposits of: (1) intertidal beach, (2) lagoon and washover, (3) tidal inlet and spit recurve and (4) storm-dominated subtidal settings. These were parts of larger barrier features, the bulk of which are preserved as highstand deposits that are diamond-bearing with varying, but generally low grades (<13 stones (diamonds) per hundred tons, spht). Intertidal beach and spit recurve deposits have higher economic grades (12-13 spht) due to the energetic sieving and mobile trapping mechanisms associated with their emplacement. In contrast, the less reworked and more sandy subtidal, tidal inlet and washover deposits have un-economic grades (<2 spht). Despite these low grades, the barrier deposits have the largest average stone (diamond) size (1-2 carats/stone, cts/stn) of the entire Namibian mega-placer, given their proximity to the ancestral Orange River outfall. This study demonstrates that barrier shoreline evolution at the fluvial/marine interface was controlled by: (1) a strong and coarse fluvial sediment supply that sustained shoreline growth on a highly energetic coast, (2) accommodation space facilitating sediment preservation and (3) short-duration, high-frequency sea-level cycles superimposed on the∼30 m regional transgression, promoting hierarchal stacking of progradational deposits. During these sea-level fluctuations, diamonds were 'farmed' from older, shelf sequences in the offshore and driven landward to accumulate in '30 m Package' highstand barrier deposits. In spite of the large supply of diamonds, their retention in these deposits was poor due to an incompetent footwall of ancestral Orange River mouth sediment and the inherent cobble-boulder size of the barrier gravels. Thus the principal process controlling diamond entrapment in these barrier deposits was kinetic sieving in a coarse-grained framework. Consequently, at the marine/fluvial interface and down-drift for ∼5 km, larger diamonds (1-2 cts/stn) were retained in low-grade (<2 spht), coarse-gravel barrier shorelines. Smaller diamonds (mostly < I cts/stn) were rejected into the northward-driven littoral sediments and further size-sorted along ∼95 km of Namibian coast to accumulate in finer, high-grade beach placers (> 100 spht) where bedrock footwall promoted such high concentrations. The gravel-dominated palaeo-Orange River mouth is considered to be the ' heart' of the Namibian mega-placer, controlling sediment and diamond supply to the littoral zone further north. Although coarse gravel is retained at the river mouth, the incompetence of this highly energetic setting to trap diamonds renders it sub-economic. This ineffectiveness at the fluvial/marine interface is thus fundamental in enriching the coastal tract farther down-drift and developing highly economic coastal placers along the Atlantic coast of south-western Africa. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2011
- Authors: Spaggiari, Renato Igino
- Date: 2011 , 2013-08-19
- Subjects: Diamond mines and mining -- Namibia Sediments (Geology) -- South Africa and Namibia -- Orange River Estuary Diamond deposits -- Namibia Orange River Estuary (Namibia and South Africa)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4927 , http://hdl.handle.net/10962/d1004636
- Description: The largest known marine diamond placer, the Namibian mega-placer, lies along the Atlantic coast of south-western Africa from the Orange River mouth 1,000 km northwards to the Namibian-Angolan border. The most economically viable portion of the Namibian mega-placer (>75 million carats recovered at >95% gem quality) comprises onshore and offshore marine deposits that are developed within ∼100km of the Orange River outfall. For much of the Cainozoic, this long-lived fluvial system has been the main conduit transporting diamonds from kimberlitic and secondary sources in the cratonic hinterland of southern Africa to the Atlantic shelf that has been neutrally buoyant over this period. Highly energetic marine processes, driven in part, by southerly winds with an attendant northward-directed longshore drift, have generated terminal placers that are preserved both onshore and offshore. This study, through detailed field sedimentological and diamond analyses, investigates the development and mineralisation of gravel barrier deposits within the ancestral Orange River mouth area during a major ∼30 m regional transgression ('30 m Package') in the Late Pliocene. At that time, diamond supply from this fluvial conduit was minimal, yet the corresponding onshore marine deposits to the north of the Orange River mouth were significantly diamond enriched, enabling large-scale alluvial diamond mining to take place for over 75 years. Of the entire coastline of south-western Africa, the most complete accumulation of the '30 m Package' is preserved within the palaeo-Orange River mouth as barrier spit and barrier beach deposits. Arranged vertically and laterally in a 16m thick succession, these are deposits of: (1) intertidal beach, (2) lagoon and washover, (3) tidal inlet and spit recurve and (4) storm-dominated subtidal settings. These were parts of larger barrier features, the bulk of which are preserved as highstand deposits that are diamond-bearing with varying, but generally low grades (<13 stones (diamonds) per hundred tons, spht). Intertidal beach and spit recurve deposits have higher economic grades (12-13 spht) due to the energetic sieving and mobile trapping mechanisms associated with their emplacement. In contrast, the less reworked and more sandy subtidal, tidal inlet and washover deposits have un-economic grades (<2 spht). Despite these low grades, the barrier deposits have the largest average stone (diamond) size (1-2 carats/stone, cts/stn) of the entire Namibian mega-placer, given their proximity to the ancestral Orange River outfall. This study demonstrates that barrier shoreline evolution at the fluvial/marine interface was controlled by: (1) a strong and coarse fluvial sediment supply that sustained shoreline growth on a highly energetic coast, (2) accommodation space facilitating sediment preservation and (3) short-duration, high-frequency sea-level cycles superimposed on the∼30 m regional transgression, promoting hierarchal stacking of progradational deposits. During these sea-level fluctuations, diamonds were 'farmed' from older, shelf sequences in the offshore and driven landward to accumulate in '30 m Package' highstand barrier deposits. In spite of the large supply of diamonds, their retention in these deposits was poor due to an incompetent footwall of ancestral Orange River mouth sediment and the inherent cobble-boulder size of the barrier gravels. Thus the principal process controlling diamond entrapment in these barrier deposits was kinetic sieving in a coarse-grained framework. Consequently, at the marine/fluvial interface and down-drift for ∼5 km, larger diamonds (1-2 cts/stn) were retained in low-grade (<2 spht), coarse-gravel barrier shorelines. Smaller diamonds (mostly < I cts/stn) were rejected into the northward-driven littoral sediments and further size-sorted along ∼95 km of Namibian coast to accumulate in finer, high-grade beach placers (> 100 spht) where bedrock footwall promoted such high concentrations. The gravel-dominated palaeo-Orange River mouth is considered to be the ' heart' of the Namibian mega-placer, controlling sediment and diamond supply to the littoral zone further north. Although coarse gravel is retained at the river mouth, the incompetence of this highly energetic setting to trap diamonds renders it sub-economic. This ineffectiveness at the fluvial/marine interface is thus fundamental in enriching the coastal tract farther down-drift and developing highly economic coastal placers along the Atlantic coast of south-western Africa. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2011
Nanomaterial modified electrodes : optimization of voltammetric sensors for pharmaceutical and industrial application
- Authors: Brimecombe, Rory Dennis
- Date: 2011
- Subjects: Voltammetry , Electrochemistry , Nanotubes , Nanostructured materials
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4101 , http://hdl.handle.net/10962/d1009721
- Description: Nanomaterials, in particular carbon nanotubes have been shown to exhibit favourable properties for the enhancement of electrochemical detection of target analytes in complex matrices. There is however scope for improvement in terms of the optimization thereof in electrochemical sensors surface modification. The aim of this thesis was to examine methods that would result in increased current response, lowered passivation and application of such modified surfaces with application to pharmaceutically and industrially relevant analytes. Current methods for enhancing the performance of carbon nanotubes include acid functionalization which not only increases the hydrophilicity of the nanotubes, and consequently their ability to provide stable (aqueous) suspensions, but also introduces electrochemically active sites. This particular approach is however not normalized in the literature. Over-exposure to acid treatment results in loss of structural integrity of the carbon nanotubes, and as such a fine balance exists between achieving these dual outcomes. Guided by high resolution scanning electron microscopy, atomic force microscopy, voltammetric and impedance studies, this thesis examined the role of the length of time of the acid functionalization process as well as the impact of activation of carbon nanotubes and fullerenes on electrochemical sensor performance. Based on desired charge transfer resistances, rate transfer coefficients and sensitivity towards redox probes the optimal length of acid functionalization for multiwalled carbon nanotubes was 9 hours and 4 hours for single-walled carbon nanotubes. Further improvements in the desired outcomes were achieved through electrochemical activation of the modified electrode surface by cycling in the presence of catechol, in a novel approach. By employing electrochemical impedance spectroscopy it was observed that catechol activation resulted in lowered charge transfer resistance, before and after activation, with functionalized multi-walled carbon nanotubes (9 hours) exhibiting the greatest decrease of 90 % and functionalized single-walled carbon nanotubes (4 hours), a 50 % decrease. Corresponding increases in the heterologous rate transfer coefficient showed a 770 % increase for functionalized multi-walled carbon nanotubes (9 hours), following catechol activation. Comparative observations for fullerenes following partial reduction in potassium hydroxide yielded a 30 % decrease in charge transfer resistance, with an increased heterologous rate transfer coefficient at a fullerene modified surface The performance of the nanomaterial modified electrodes was applied to the detection of wortmannin with applications in bioprocess control and in the pharmaceutical sector as well as to the detection and monitoring of the industrial dye Reactive red. Of particular relevance to these analytes was the assessment of the nanomaterial modified electrodes for enhanced stability, reproducibility, sensitivity and decreased passivation effects. In this study the first known account of wortmannin detection through electrochemical methods is reported. Voltammetric characterization of wortmannin revealed an irreversible cathodic process with a total number of 4 electrons and a diffusion coefficient of 1.19 x 10-7 cm².s⁻¹. At a functionalized multiwalled carbon nanotubes modified glassy carbon electrode a limit of detection of 0.128 nmol.cm⁻³ was obtained, and with limited surface passivation the detection scheme afforded pertinent analyses in biological media representing a substantial improvement over chromatographic detection methods. This study also provided the first account of the voltammetric detection of reactive red, competing favourably with traditional spectroscopic methods for monitoring biodegradation of this compound in real time.
- Full Text:
- Date Issued: 2011
- Authors: Brimecombe, Rory Dennis
- Date: 2011
- Subjects: Voltammetry , Electrochemistry , Nanotubes , Nanostructured materials
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4101 , http://hdl.handle.net/10962/d1009721
- Description: Nanomaterials, in particular carbon nanotubes have been shown to exhibit favourable properties for the enhancement of electrochemical detection of target analytes in complex matrices. There is however scope for improvement in terms of the optimization thereof in electrochemical sensors surface modification. The aim of this thesis was to examine methods that would result in increased current response, lowered passivation and application of such modified surfaces with application to pharmaceutically and industrially relevant analytes. Current methods for enhancing the performance of carbon nanotubes include acid functionalization which not only increases the hydrophilicity of the nanotubes, and consequently their ability to provide stable (aqueous) suspensions, but also introduces electrochemically active sites. This particular approach is however not normalized in the literature. Over-exposure to acid treatment results in loss of structural integrity of the carbon nanotubes, and as such a fine balance exists between achieving these dual outcomes. Guided by high resolution scanning electron microscopy, atomic force microscopy, voltammetric and impedance studies, this thesis examined the role of the length of time of the acid functionalization process as well as the impact of activation of carbon nanotubes and fullerenes on electrochemical sensor performance. Based on desired charge transfer resistances, rate transfer coefficients and sensitivity towards redox probes the optimal length of acid functionalization for multiwalled carbon nanotubes was 9 hours and 4 hours for single-walled carbon nanotubes. Further improvements in the desired outcomes were achieved through electrochemical activation of the modified electrode surface by cycling in the presence of catechol, in a novel approach. By employing electrochemical impedance spectroscopy it was observed that catechol activation resulted in lowered charge transfer resistance, before and after activation, with functionalized multi-walled carbon nanotubes (9 hours) exhibiting the greatest decrease of 90 % and functionalized single-walled carbon nanotubes (4 hours), a 50 % decrease. Corresponding increases in the heterologous rate transfer coefficient showed a 770 % increase for functionalized multi-walled carbon nanotubes (9 hours), following catechol activation. Comparative observations for fullerenes following partial reduction in potassium hydroxide yielded a 30 % decrease in charge transfer resistance, with an increased heterologous rate transfer coefficient at a fullerene modified surface The performance of the nanomaterial modified electrodes was applied to the detection of wortmannin with applications in bioprocess control and in the pharmaceutical sector as well as to the detection and monitoring of the industrial dye Reactive red. Of particular relevance to these analytes was the assessment of the nanomaterial modified electrodes for enhanced stability, reproducibility, sensitivity and decreased passivation effects. In this study the first known account of wortmannin detection through electrochemical methods is reported. Voltammetric characterization of wortmannin revealed an irreversible cathodic process with a total number of 4 electrons and a diffusion coefficient of 1.19 x 10-7 cm².s⁻¹. At a functionalized multiwalled carbon nanotubes modified glassy carbon electrode a limit of detection of 0.128 nmol.cm⁻³ was obtained, and with limited surface passivation the detection scheme afforded pertinent analyses in biological media representing a substantial improvement over chromatographic detection methods. This study also provided the first account of the voltammetric detection of reactive red, competing favourably with traditional spectroscopic methods for monitoring biodegradation of this compound in real time.
- Full Text:
- Date Issued: 2011
The development of novel cancer targeting agents
- Authors: Knoetze, Steyn
- Date: 2011
- Subjects: Cancer -- Research , Cancer -- Treatment
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10397 , http://hdl.handle.net/10948/d1010636 , Cancer -- Research , Cancer -- Treatment
- Description: The search for the cure for cancer is currently a multi-billion dollar industry and the search for the elusive “magic bullet”, i.e. the perfect cancer drug that would interact therapeutically with cancerous tissues while having a minimal effect on healthy cells, is the topic of many research studies in the world today. A large number of novel drugs or drug complexes and conjugates are being synthesized and subjected to rigorous evaluation in the race to find the perfect cure. ECDG (Ethylene diCysteine DeoxyGlucose) seems to have promising cancer targeting ability. Even though this compound has been described in a few publications, we could not find any reference to the current use of ECDG in oncology clinics, either as a therapeutic agent, or as a diagnostic tool for imaging purposes. It was also not possible to purchase pure ECDG anywhere in the world. This prompted us to further investigate ECDG as a possible candidate for cancer targeting research, either as an imaging agent for cancer diagnosis or complexed with an anti-cancer agent for therapeutic purposes. Detailed investigations done in our laboratory can be divided into the following categories: - Development of a synthetic method for ECDG on a multigram scale ; - Purification of prepared ECDG not using the described dialysis method that only allows the purification of small quantities of ECDG (mg scale) ; Detailed investigation of the chemistry involved in the preparation of pure ECDG and its metal complexes ; - Investigation of the stability of ECDG and its metal complexes that is essential data required for any pharmaceutical agent ; - Preparation of ECDG complexes for use as a diagnostic tool, i.e. complexation with 99mTc ; Investigation of the bio distribution of ECDG-ReO complexes ; - Preparation of an ECDG kit as a diagnostic tool for use in oncology clinics. The development of novel aromatic ligands having similar characteristics compared to ECDG, containing an N2S2 chromophore as donor atoms, to further investigate their targeting capabilities, have also been investigated. All intermediates and final compounds were characterized mainly by ESI MS, in some cases IR and NMR whenever available. Successful preparation and purification of ECDG ands its metal complexes was achieved and extensively characterized and evaluated. Efforts directed towards the development of ECDG at NECSA, South Africa, were also rewarded with significant success. Furthermore, significant development regarding the synthesis of two novel compounds with ECDG-like characteristics was also completed.
- Full Text:
- Date Issued: 2011
- Authors: Knoetze, Steyn
- Date: 2011
- Subjects: Cancer -- Research , Cancer -- Treatment
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10397 , http://hdl.handle.net/10948/d1010636 , Cancer -- Research , Cancer -- Treatment
- Description: The search for the cure for cancer is currently a multi-billion dollar industry and the search for the elusive “magic bullet”, i.e. the perfect cancer drug that would interact therapeutically with cancerous tissues while having a minimal effect on healthy cells, is the topic of many research studies in the world today. A large number of novel drugs or drug complexes and conjugates are being synthesized and subjected to rigorous evaluation in the race to find the perfect cure. ECDG (Ethylene diCysteine DeoxyGlucose) seems to have promising cancer targeting ability. Even though this compound has been described in a few publications, we could not find any reference to the current use of ECDG in oncology clinics, either as a therapeutic agent, or as a diagnostic tool for imaging purposes. It was also not possible to purchase pure ECDG anywhere in the world. This prompted us to further investigate ECDG as a possible candidate for cancer targeting research, either as an imaging agent for cancer diagnosis or complexed with an anti-cancer agent for therapeutic purposes. Detailed investigations done in our laboratory can be divided into the following categories: - Development of a synthetic method for ECDG on a multigram scale ; - Purification of prepared ECDG not using the described dialysis method that only allows the purification of small quantities of ECDG (mg scale) ; Detailed investigation of the chemistry involved in the preparation of pure ECDG and its metal complexes ; - Investigation of the stability of ECDG and its metal complexes that is essential data required for any pharmaceutical agent ; - Preparation of ECDG complexes for use as a diagnostic tool, i.e. complexation with 99mTc ; Investigation of the bio distribution of ECDG-ReO complexes ; - Preparation of an ECDG kit as a diagnostic tool for use in oncology clinics. The development of novel aromatic ligands having similar characteristics compared to ECDG, containing an N2S2 chromophore as donor atoms, to further investigate their targeting capabilities, have also been investigated. All intermediates and final compounds were characterized mainly by ESI MS, in some cases IR and NMR whenever available. Successful preparation and purification of ECDG ands its metal complexes was achieved and extensively characterized and evaluated. Efforts directed towards the development of ECDG at NECSA, South Africa, were also rewarded with significant success. Furthermore, significant development regarding the synthesis of two novel compounds with ECDG-like characteristics was also completed.
- Full Text:
- Date Issued: 2011
Adaptation choices, community perceptions, livelihood linkages and income dynamics for district producer communities surrounding Nyatana Game Park in Zimbabwe
- Authors: Taruvinga, Amon
- Date: 2011
- Subjects: Game reserves -- Zimbabwe , Wildlife conservation -- Zimbabwe , Wildlife management -- Zimbabwe , Sustainable development -- Zimbabwe , Game farms -- Zimbabwe , Rural poor -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD (Agricultural Economics)
- Identifier: vital:11154 , http://hdl.handle.net/10353/476 , Game reserves -- Zimbabwe , Wildlife conservation -- Zimbabwe , Wildlife management -- Zimbabwe , Sustainable development -- Zimbabwe , Game farms -- Zimbabwe , Rural poor -- Zimbabwe
- Description: This thesis explores human-wildlife interactions under community managed game parks. The thesis consists of an introductory chapter, study location chapter and four self-contained studies based on different samples from created clusters surrounding Nyatana Game Park, which make up the rest of the thesis chapters. Chapter one presents an introductory overview of wildlife management in Zimbabwe, specifically looking at human-wildlife interactions under CAMPFIRE projects, welfare dynamics and conservation implications for the surrounding communities who share boundaries with community-managed game parks. The chapter concludes by highlighting the challenges facing community-based wildlife conservation in Zimbabwe as well as the key concepts that will be the subject of the rest of the thesis. Chapter two presents the study location; it highlights the road map to the study area, starting with the provincial location, and indicates the specific districts from which respondents were selected. A brief agro-ecological summary of the study area is also presented; it looks specifically at climate, vegetation and a demographic data of the study area. Chapter three: Can game parks be trusted as livelihood sources? To answer this topical question, Chapter three explores livelihood adaptation strategies for households who share boundaries with Nyatana Game Park. Most of the community managed game parks, under CAMPFIRE principles in Zimbabwe, were established with the primary objective of generating revenue for the surrounding communities; this was done in the hope of using positive returns from game farming to promote the conservation of wildlife. Has this materialised in practice? Descriptive results from this study seem to suggest otherwise, where mixed farming and gold panning were the major livelihood adaptation choices reported by most households. The revenue from game farming was reported to be too low and inconsistent, to such an extent that the majority of the community regarded it as risky and unreliable. A multinomial logistic regression model for correlates of adaptation choices indicated that access to credit, markets, and extension may be some of the current institutional constraints inhibiting households from accessing off-farm sources for their livelihoods. In addition, household size, gender and age may enhance the adaptive capacity of households to move out of risky crop faming into other off-farm portfolio diversifications. The study, therefore, suggests that game parks, according to the evidence uncovered by the study, may not be trusted as a reliable and sustainable livelihood source. If local communities who share boundaries with game parks do not view them as reliable and sustainable livelihood sources, as concluded in Chapter three, how can they (local communities) be trusted to conserve them? To assess their perceptions of game parks, Chapter four presents a multinomial logistic regression model for perceptions of society on game parks using the African elephant as a typical example. The results suggest that Problem Animal Control (PAC) perceptions, livestock predation and issues of low and poor revenue distribution may be some of the critical perceptions capable of influencing surrounding communities to negatively participate in the conservation of wildlife. The results further suggest that using wildlife proceeds to finance observable local common pool infrastructure may positively influence the surrounding communities to conserve wildlife. The chief conclusion regarding game parks, therefore, was that the surrounding communities were in favour of the obliteration pathway, although minimal conservation perceptions were also available. Given the negative conclusions regarding game parks, as suggested in Chapters three and four, citizens would then wonder if any meaningful hope for community managed game parks exists. Chapter five probes the buffer zone livelihood link under community managed game parks, using evidence from the Nyatana Game Park. The binary logistic regression model results, for buffer zone participation and resource extraction combinations by surrounding communities, suggest that resource extraction may be market driven rather than focussing on domestic consumption. The study therefore concludes that the buffer zone livelihood link as currently practiced, though potential, may fail to address the livelihood expectations of the sub-district producer communities. The study therefore calls for extreme caution whenever the buffer zone livelihood link is considered, because several institutional and design conflicts exist within this dynamic. In Chapter six, the study further probed the buffer zone income dynamics for the sub-district producer community. The results of descriptive statistics suggest that the contribution of buffer zone activities to household income may be significant with a positive correlation to household agricultural income for communities who reside inside or close to the park (primary sub-district producer community). Using the Gini decomposition approach and Lorenz curves, the study concluded that a buffer zone income may be capable of contributing to more equally distributed incomes for rural communities who share boundaries with game parks. With respect to the correlates of household income, the results suggest that household size and age may negatively influence income from buffer zone activities, while gender may have a positive effect. This was also true for education and Livestock Units (LUs) with respect to income from self employment; the former positively and the latter negatively related. The results further suggest that land size may also be positively significant in order to explain income from agriculture as well as total income. With regard to the distance from the buffer zone, the results suggest a negative influence with respect to the buffer zone, agriculture and total income. The implied message therefore suggests that buffer zones may provide active livelihood sources which are capable of financing rural household agriculture. The income equalizing effect which is portrayed may also further imply that, if correctly targeted and promoted, a buffer zone income could possibly address the current income inequality which is generic in rural areas. However, this potential may not be realized due to the current buffer zone design status (created for local secondary use as opposed to commercial primary use), restrictive policies and poor institutional support. With this dilemma facing community managed game parks (threats as summarised in Chapters three and four amid the potential hope summarized in Chapters five and six), Chapter 7 concludes the study by suggesting that the human-wildlife interaction model, though currently theoretical, may have significant practical potential in addressing the livelihoods of the surrounding communities as well as promoting the conservation of wildlife. This could be possible if available challenges that range from low revenue, insecure property rights, high human-elephant conflict and institutional design conflict for buffer zone utilization are corrected by means of the free market system. This would allow market forces to deliver on the expectations of the ―human-wildlife interactions model‖ – sustainable livelihoods for the former and intergenerational conservation for the latter.
- Full Text:
- Date Issued: 2011
- Authors: Taruvinga, Amon
- Date: 2011
- Subjects: Game reserves -- Zimbabwe , Wildlife conservation -- Zimbabwe , Wildlife management -- Zimbabwe , Sustainable development -- Zimbabwe , Game farms -- Zimbabwe , Rural poor -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD (Agricultural Economics)
- Identifier: vital:11154 , http://hdl.handle.net/10353/476 , Game reserves -- Zimbabwe , Wildlife conservation -- Zimbabwe , Wildlife management -- Zimbabwe , Sustainable development -- Zimbabwe , Game farms -- Zimbabwe , Rural poor -- Zimbabwe
- Description: This thesis explores human-wildlife interactions under community managed game parks. The thesis consists of an introductory chapter, study location chapter and four self-contained studies based on different samples from created clusters surrounding Nyatana Game Park, which make up the rest of the thesis chapters. Chapter one presents an introductory overview of wildlife management in Zimbabwe, specifically looking at human-wildlife interactions under CAMPFIRE projects, welfare dynamics and conservation implications for the surrounding communities who share boundaries with community-managed game parks. The chapter concludes by highlighting the challenges facing community-based wildlife conservation in Zimbabwe as well as the key concepts that will be the subject of the rest of the thesis. Chapter two presents the study location; it highlights the road map to the study area, starting with the provincial location, and indicates the specific districts from which respondents were selected. A brief agro-ecological summary of the study area is also presented; it looks specifically at climate, vegetation and a demographic data of the study area. Chapter three: Can game parks be trusted as livelihood sources? To answer this topical question, Chapter three explores livelihood adaptation strategies for households who share boundaries with Nyatana Game Park. Most of the community managed game parks, under CAMPFIRE principles in Zimbabwe, were established with the primary objective of generating revenue for the surrounding communities; this was done in the hope of using positive returns from game farming to promote the conservation of wildlife. Has this materialised in practice? Descriptive results from this study seem to suggest otherwise, where mixed farming and gold panning were the major livelihood adaptation choices reported by most households. The revenue from game farming was reported to be too low and inconsistent, to such an extent that the majority of the community regarded it as risky and unreliable. A multinomial logistic regression model for correlates of adaptation choices indicated that access to credit, markets, and extension may be some of the current institutional constraints inhibiting households from accessing off-farm sources for their livelihoods. In addition, household size, gender and age may enhance the adaptive capacity of households to move out of risky crop faming into other off-farm portfolio diversifications. The study, therefore, suggests that game parks, according to the evidence uncovered by the study, may not be trusted as a reliable and sustainable livelihood source. If local communities who share boundaries with game parks do not view them as reliable and sustainable livelihood sources, as concluded in Chapter three, how can they (local communities) be trusted to conserve them? To assess their perceptions of game parks, Chapter four presents a multinomial logistic regression model for perceptions of society on game parks using the African elephant as a typical example. The results suggest that Problem Animal Control (PAC) perceptions, livestock predation and issues of low and poor revenue distribution may be some of the critical perceptions capable of influencing surrounding communities to negatively participate in the conservation of wildlife. The results further suggest that using wildlife proceeds to finance observable local common pool infrastructure may positively influence the surrounding communities to conserve wildlife. The chief conclusion regarding game parks, therefore, was that the surrounding communities were in favour of the obliteration pathway, although minimal conservation perceptions were also available. Given the negative conclusions regarding game parks, as suggested in Chapters three and four, citizens would then wonder if any meaningful hope for community managed game parks exists. Chapter five probes the buffer zone livelihood link under community managed game parks, using evidence from the Nyatana Game Park. The binary logistic regression model results, for buffer zone participation and resource extraction combinations by surrounding communities, suggest that resource extraction may be market driven rather than focussing on domestic consumption. The study therefore concludes that the buffer zone livelihood link as currently practiced, though potential, may fail to address the livelihood expectations of the sub-district producer communities. The study therefore calls for extreme caution whenever the buffer zone livelihood link is considered, because several institutional and design conflicts exist within this dynamic. In Chapter six, the study further probed the buffer zone income dynamics for the sub-district producer community. The results of descriptive statistics suggest that the contribution of buffer zone activities to household income may be significant with a positive correlation to household agricultural income for communities who reside inside or close to the park (primary sub-district producer community). Using the Gini decomposition approach and Lorenz curves, the study concluded that a buffer zone income may be capable of contributing to more equally distributed incomes for rural communities who share boundaries with game parks. With respect to the correlates of household income, the results suggest that household size and age may negatively influence income from buffer zone activities, while gender may have a positive effect. This was also true for education and Livestock Units (LUs) with respect to income from self employment; the former positively and the latter negatively related. The results further suggest that land size may also be positively significant in order to explain income from agriculture as well as total income. With regard to the distance from the buffer zone, the results suggest a negative influence with respect to the buffer zone, agriculture and total income. The implied message therefore suggests that buffer zones may provide active livelihood sources which are capable of financing rural household agriculture. The income equalizing effect which is portrayed may also further imply that, if correctly targeted and promoted, a buffer zone income could possibly address the current income inequality which is generic in rural areas. However, this potential may not be realized due to the current buffer zone design status (created for local secondary use as opposed to commercial primary use), restrictive policies and poor institutional support. With this dilemma facing community managed game parks (threats as summarised in Chapters three and four amid the potential hope summarized in Chapters five and six), Chapter 7 concludes the study by suggesting that the human-wildlife interaction model, though currently theoretical, may have significant practical potential in addressing the livelihoods of the surrounding communities as well as promoting the conservation of wildlife. This could be possible if available challenges that range from low revenue, insecure property rights, high human-elephant conflict and institutional design conflict for buffer zone utilization are corrected by means of the free market system. This would allow market forces to deliver on the expectations of the ―human-wildlife interactions model‖ – sustainable livelihoods for the former and intergenerational conservation for the latter.
- Full Text:
- Date Issued: 2011
Risk-based assessment of environmental asbestos contamination in the Northern Cape and North West provinces of South Africa
- Authors: Jones, Robert Ryan
- Date: 2011
- Subjects: Asbestos industry -- Health aspects -- South Africa -- Northern Cape Asbestos industry -- Health aspects -- South Africa -- North West Environmental risk assessment -- South Africa-- Northern Cape Environmental risk assessment -- North West Asbestos -- Toxicology -- South Africa -- Northern Cape Asbestos -- Toxicology -- South Africa -- North West Tailings (Metallurgy) -- Waste disposal -- South Africa -- Northern Cape Tailings (Metallurgy) -- Waste disposal -- South Africa -- North West
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4780 , http://hdl.handle.net/10962/d1012612
- Description: The commercial mining of asbestos occurred in four Provinces of South Africa (Northern Cape, North West, Limpopo and Mpumalanga). It was initiated in the late 1800's and lasted for over a hundred years into the beginning of this century. As a producer of amphibole asbestos, South Africa far outpaced every other country being responsible for 97% of global production. The last crocidolite mine closed in 1996 and chrysotile in 2002. Anecdotal information concerning environmental contamination as a result of the former mining activities and the improper disposal of mine waste tailings has been reported by a variety of authors. Few comprehensive or systematic surveys have been conducted to date to document this issue and very little quantifiable research has been completed on the communities located in close proximity to the former mine sites to determine the extent of contamination. In 2004-2006 communities were surveyed within the Northern Cape and North West Provinces to determine the extent and severity of environmental contamination. This research developed and applied a methodology to select those communities suspected of environmental contamination, a targeted survey methodology, and a protocol for rapid sample laboratory analysis. A total of 41 communities were initially predicted by the model to be suspected for environmental asbestos contamination. Based on the inclusion of local knowledge, a final 36 communities were selected for a screening-level field assessment, 34 of which were found to contain environmental asbestos contamination at rates ranging from 20 to 100% of the surveyed locations. A total of 1 843 samples of soil and building material were collected in the screening level assessment. One community (Ga-Mopedi) was selected as being representative of the total cohort and a more detailed house to house survey was completed. A total of 1 486 samples were collected during the detailed survey. Results of the detailed survey revealed 26.2% of the homes were contaminated with asbestos containing soil and/or building material. A theoretical quantitative cumulative exposure assessment was developed to estimate the disease burden within the study area population of 126,130 individuals within the surveyed communities resulting in a predicted range of 25-52.4 excess deaths per year from lung cancer and mesothelioma due solely to environmental exposures to asbestos pollution.
- Full Text:
- Date Issued: 2011
- Authors: Jones, Robert Ryan
- Date: 2011
- Subjects: Asbestos industry -- Health aspects -- South Africa -- Northern Cape Asbestos industry -- Health aspects -- South Africa -- North West Environmental risk assessment -- South Africa-- Northern Cape Environmental risk assessment -- North West Asbestos -- Toxicology -- South Africa -- Northern Cape Asbestos -- Toxicology -- South Africa -- North West Tailings (Metallurgy) -- Waste disposal -- South Africa -- Northern Cape Tailings (Metallurgy) -- Waste disposal -- South Africa -- North West
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4780 , http://hdl.handle.net/10962/d1012612
- Description: The commercial mining of asbestos occurred in four Provinces of South Africa (Northern Cape, North West, Limpopo and Mpumalanga). It was initiated in the late 1800's and lasted for over a hundred years into the beginning of this century. As a producer of amphibole asbestos, South Africa far outpaced every other country being responsible for 97% of global production. The last crocidolite mine closed in 1996 and chrysotile in 2002. Anecdotal information concerning environmental contamination as a result of the former mining activities and the improper disposal of mine waste tailings has been reported by a variety of authors. Few comprehensive or systematic surveys have been conducted to date to document this issue and very little quantifiable research has been completed on the communities located in close proximity to the former mine sites to determine the extent of contamination. In 2004-2006 communities were surveyed within the Northern Cape and North West Provinces to determine the extent and severity of environmental contamination. This research developed and applied a methodology to select those communities suspected of environmental contamination, a targeted survey methodology, and a protocol for rapid sample laboratory analysis. A total of 41 communities were initially predicted by the model to be suspected for environmental asbestos contamination. Based on the inclusion of local knowledge, a final 36 communities were selected for a screening-level field assessment, 34 of which were found to contain environmental asbestos contamination at rates ranging from 20 to 100% of the surveyed locations. A total of 1 843 samples of soil and building material were collected in the screening level assessment. One community (Ga-Mopedi) was selected as being representative of the total cohort and a more detailed house to house survey was completed. A total of 1 486 samples were collected during the detailed survey. Results of the detailed survey revealed 26.2% of the homes were contaminated with asbestos containing soil and/or building material. A theoretical quantitative cumulative exposure assessment was developed to estimate the disease burden within the study area population of 126,130 individuals within the surveyed communities resulting in a predicted range of 25-52.4 excess deaths per year from lung cancer and mesothelioma due solely to environmental exposures to asbestos pollution.
- Full Text:
- Date Issued: 2011
The existence of the value premium on the Johannesburg Stock Exchange from 1972 to 2001 and extrapolation as explanation
- Authors: Beukes, Anna
- Date: 2011
- Subjects: Johannesburg Stock Exchange Stocks -- Prices -- South Africa Rational expectations (Economic theory) Investments -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:977 , http://hdl.handle.net/10962/d1002711
- Description: This study investigates the existence of the value premium in South Africa’s equity market, and tests extrapolation as a possible explanation for it. The value premium refers to the widely reported superior performance of share price returns of value companies compared to growth companies. The value premium represents an anomaly in mainstream rational finance theory, because it should not persist, unless it could be explained as the result of some composite form of risk. What is highly vexing is the fact that the value premium not only persists in most financial markets over a long period, but that the risk explanation cannot be upheld convincingly. This contributed to the rise of behavioral finance, an approach which introduces psychological factors to provide new explanations for financial phenomena. The behavioral finance explanation for the value premium observation is extrapolation (the tendency to project recent experience too far into the future). This study applies propositions and methods from behavioral finance to investigate the South African equity market. The existence of a value premium in South Africa was investigated by using twenty-nine years’ worth of accounting and share price data. The study employed one- and two-dimensional tests for portfolio formation, and tracked share price returns for up to five years after portfolio formation. The results indicated that a statistically and economically significant value premium existed in South Africa for the period between 1972 and 2001. Extrapolation as a potential explanation for the value premium observation was investigated by applying internationally used methods. Extrapolation was found to provide a robust explanation for the South African value premium.
- Full Text:
- Date Issued: 2011
- Authors: Beukes, Anna
- Date: 2011
- Subjects: Johannesburg Stock Exchange Stocks -- Prices -- South Africa Rational expectations (Economic theory) Investments -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:977 , http://hdl.handle.net/10962/d1002711
- Description: This study investigates the existence of the value premium in South Africa’s equity market, and tests extrapolation as a possible explanation for it. The value premium refers to the widely reported superior performance of share price returns of value companies compared to growth companies. The value premium represents an anomaly in mainstream rational finance theory, because it should not persist, unless it could be explained as the result of some composite form of risk. What is highly vexing is the fact that the value premium not only persists in most financial markets over a long period, but that the risk explanation cannot be upheld convincingly. This contributed to the rise of behavioral finance, an approach which introduces psychological factors to provide new explanations for financial phenomena. The behavioral finance explanation for the value premium observation is extrapolation (the tendency to project recent experience too far into the future). This study applies propositions and methods from behavioral finance to investigate the South African equity market. The existence of a value premium in South Africa was investigated by using twenty-nine years’ worth of accounting and share price data. The study employed one- and two-dimensional tests for portfolio formation, and tracked share price returns for up to five years after portfolio formation. The results indicated that a statistically and economically significant value premium existed in South Africa for the period between 1972 and 2001. Extrapolation as a potential explanation for the value premium observation was investigated by applying internationally used methods. Extrapolation was found to provide a robust explanation for the South African value premium.
- Full Text:
- Date Issued: 2011