Wage differentials by sector and gender in Botswana
- Authors: Motswapong, Masedi
- Date: 2023-04
- Subjects: Wage differentials -- Botswana , Wage Decomposition
- Language: English
- Type: Doctoral's theses , text
- Identifier: http://hdl.handle.net/10948/62128 , vital:71998
- Description: The study examines wage differentials in the public and private sectors and gender wage gaps within these sectors in Botswana. Raw data from three nationally representative surveys collected is used. These surveys include the 2005/06 Labour force, the 2015/16 Multi-Topic Household and the 2019 Quarterly Multi-Topic. To address the set objectives, the study utilises the quantile regression model and decomposition methods proposed by Firpo, Fortin and Lemieux (2009) and further used the reweighted RIF-OLS OaxacaBlinder decomposition method proposed by Rios-Avila (2020). Results from three surveys demonstrate evidence of wage inequalities in Botswana. Findings revealed that the wage differential in the public and private sectors has weakened over the years, though it is still a significant concern. The public-private sector wage gap decreased from 72% in 2005/06 to 56% in 2019. However, a different trend is observed in the gender wage differentials, where the gap gradually increased over time. Gender wage gaps in the public sector were 4% in 2005/06; in 2015/16, the gap increased to 27% and 49% in 2019. On the other hand, in the private sector, the average wages were 7.34 and 6.98 for males and females in 2005/06, respectively, implying a wage gap of 35%. This trend holds for the other two samples. The gender wage gap in 2015/16 fell to 23% and increased to 28% in 2019. Results from the quantile regression estimates show that returns to education differ in both the sectoral and gender sections. Further, for males and females, returns for education tend to rise as the education level increases. Returns for education for the private sector are higher than for the public sector. For gender wage differences, education returns for females are higher than for males at all levels, supporting findings that females are more educated on average than males. For decomposition results, findings show that observed characteristics, such as education levels, negatively affect wages at the lower levels and positively at other parts of the distribution in the sectoral wage section. For the gender wage gap section, results show that workers’ characteristics had mixed contributions to the wage gap; it narrows the gap at the lower levels and widens it at higher levels of the wage distribution. Further, results suggest the presence of labour market discrimination and evidence of the “sticky-floor” viii effect in both sectors. Additionally, findings from the reweighting RIF-Oaxaca estimates show that the public-private sector wage gap takes an inverted U-shaped distribution in different levels of the wage distribution. Similarly, composition effects positively affect the gap at lower levels, whereas wage structure effects affect the wage gap at the highest distribution level. Overall, the study’s findings have some significant policy recommendations. The study has indicated that the country has no policy to reduce or eliminate wage differentials in the labour market. Hence, Botswana policymakers need to formulate policies to eliminate wage inequalities. Furthermore, it is recommended that the government should continue investing in human capital development. Education is vital in bridging the wage gap within the labour market. Additionally, there is a need to promote tolerance within society and promote ways of appreciating women’s work. It is also recommended that males be encouraged to work in jobs where women are overrepresented. The study's findings contribute to the ongoing wage inequality debate, and it is hoped that the study will benefit policymakers in Botswana. , Thesis (PhD) -- Faculty of Faculty of Business and Economic Sciences, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Motswapong, Masedi
- Date: 2023-04
- Subjects: Wage differentials -- Botswana , Wage Decomposition
- Language: English
- Type: Doctoral's theses , text
- Identifier: http://hdl.handle.net/10948/62128 , vital:71998
- Description: The study examines wage differentials in the public and private sectors and gender wage gaps within these sectors in Botswana. Raw data from three nationally representative surveys collected is used. These surveys include the 2005/06 Labour force, the 2015/16 Multi-Topic Household and the 2019 Quarterly Multi-Topic. To address the set objectives, the study utilises the quantile regression model and decomposition methods proposed by Firpo, Fortin and Lemieux (2009) and further used the reweighted RIF-OLS OaxacaBlinder decomposition method proposed by Rios-Avila (2020). Results from three surveys demonstrate evidence of wage inequalities in Botswana. Findings revealed that the wage differential in the public and private sectors has weakened over the years, though it is still a significant concern. The public-private sector wage gap decreased from 72% in 2005/06 to 56% in 2019. However, a different trend is observed in the gender wage differentials, where the gap gradually increased over time. Gender wage gaps in the public sector were 4% in 2005/06; in 2015/16, the gap increased to 27% and 49% in 2019. On the other hand, in the private sector, the average wages were 7.34 and 6.98 for males and females in 2005/06, respectively, implying a wage gap of 35%. This trend holds for the other two samples. The gender wage gap in 2015/16 fell to 23% and increased to 28% in 2019. Results from the quantile regression estimates show that returns to education differ in both the sectoral and gender sections. Further, for males and females, returns for education tend to rise as the education level increases. Returns for education for the private sector are higher than for the public sector. For gender wage differences, education returns for females are higher than for males at all levels, supporting findings that females are more educated on average than males. For decomposition results, findings show that observed characteristics, such as education levels, negatively affect wages at the lower levels and positively at other parts of the distribution in the sectoral wage section. For the gender wage gap section, results show that workers’ characteristics had mixed contributions to the wage gap; it narrows the gap at the lower levels and widens it at higher levels of the wage distribution. Further, results suggest the presence of labour market discrimination and evidence of the “sticky-floor” viii effect in both sectors. Additionally, findings from the reweighting RIF-Oaxaca estimates show that the public-private sector wage gap takes an inverted U-shaped distribution in different levels of the wage distribution. Similarly, composition effects positively affect the gap at lower levels, whereas wage structure effects affect the wage gap at the highest distribution level. Overall, the study’s findings have some significant policy recommendations. The study has indicated that the country has no policy to reduce or eliminate wage differentials in the labour market. Hence, Botswana policymakers need to formulate policies to eliminate wage inequalities. Furthermore, it is recommended that the government should continue investing in human capital development. Education is vital in bridging the wage gap within the labour market. Additionally, there is a need to promote tolerance within society and promote ways of appreciating women’s work. It is also recommended that males be encouraged to work in jobs where women are overrepresented. The study's findings contribute to the ongoing wage inequality debate, and it is hoped that the study will benefit policymakers in Botswana. , Thesis (PhD) -- Faculty of Faculty of Business and Economic Sciences, 2023
- Full Text:
- Date Issued: 2023-04
Women at work: A Muslim perspective
- Authors: Arghedien, Nuraan
- Date: 2023-04
- Subjects: Personnel management , Muslim women
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/60510 , vital:65640
- Description: Globally, women, including Muslim women face challenges advancing within their careers. This is supported by research focusing on the advancement of women. However, a paucity of research exists, focusing on the factors contributing to specifically the success and advancement of Muslim women. This study therefore explored the factors impacting on the experienced career success of women, particularly Muslim women and sought to identify additional barriers faced by Muslim women in the work context. In addition, the study identified interventions that can be used to enhance their success. For the purpose of this study, experienced career success referred to the subjective view of success individuals hold of themselves in relation to their careers. The target population of this study included women and men, irrespective of religious orientation or ethnic profile who reside and work in South Africa (n=243). A self-administered online survey was developed and distributed via an electronic link to individuals within a professional network as well as on various social media platforms. In addition, the study was subjected to various statistical analyses, including an Exploratory Factor Analysis, Reliability, Multiple Correlations, and Group Comparisons using ANOVAs, Tukey HSD, Independent Sample t-tests and Cohen’s d. Moreover, the qualitative analysis included ATLAS.ti, a manual search and the use of word clouds to extract themes that were highlighted or emphasised in the empirical study. The main findings of this study suggest that there are various factors impacting on the experienced career success of Muslim women. Positive significant relationships were found between Internal Factors and Success Indicators, indicating that the higher the level of motivation, the more successful are Muslim women. In addition, Organisational Factors and Success Indicators showed a positive relationship, implying that the importance placed on career-related interventions and commitment from top management influence the success of Muslim women. A significant relationship was found between Organisational Success Strategies and Success Indicators which means that the more aware and exposed Muslim women are to the identified career-related interventions, the greater their success. x No relationships were evident between gender and success, nor were differences found in the responses of men and women, contrary to the perception that the extent to which the factors apply to men and women are different. Furthermore, a model was developed based on the theoretical underpinnings and empirical evidence to assist in understanding the factors impacting on the experienced success of Muslim women. Additionally, strategies in the form of recommendations were advised with the aim of enhancing the experienced success of Muslim women. This study contributes to the body of knowledge relating to the advancement of Muslim women in the South African context. , Thesis (PhD) -- Faculty of Business and Economic Science, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Arghedien, Nuraan
- Date: 2023-04
- Subjects: Personnel management , Muslim women
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/60510 , vital:65640
- Description: Globally, women, including Muslim women face challenges advancing within their careers. This is supported by research focusing on the advancement of women. However, a paucity of research exists, focusing on the factors contributing to specifically the success and advancement of Muslim women. This study therefore explored the factors impacting on the experienced career success of women, particularly Muslim women and sought to identify additional barriers faced by Muslim women in the work context. In addition, the study identified interventions that can be used to enhance their success. For the purpose of this study, experienced career success referred to the subjective view of success individuals hold of themselves in relation to their careers. The target population of this study included women and men, irrespective of religious orientation or ethnic profile who reside and work in South Africa (n=243). A self-administered online survey was developed and distributed via an electronic link to individuals within a professional network as well as on various social media platforms. In addition, the study was subjected to various statistical analyses, including an Exploratory Factor Analysis, Reliability, Multiple Correlations, and Group Comparisons using ANOVAs, Tukey HSD, Independent Sample t-tests and Cohen’s d. Moreover, the qualitative analysis included ATLAS.ti, a manual search and the use of word clouds to extract themes that were highlighted or emphasised in the empirical study. The main findings of this study suggest that there are various factors impacting on the experienced career success of Muslim women. Positive significant relationships were found between Internal Factors and Success Indicators, indicating that the higher the level of motivation, the more successful are Muslim women. In addition, Organisational Factors and Success Indicators showed a positive relationship, implying that the importance placed on career-related interventions and commitment from top management influence the success of Muslim women. A significant relationship was found between Organisational Success Strategies and Success Indicators which means that the more aware and exposed Muslim women are to the identified career-related interventions, the greater their success. x No relationships were evident between gender and success, nor were differences found in the responses of men and women, contrary to the perception that the extent to which the factors apply to men and women are different. Furthermore, a model was developed based on the theoretical underpinnings and empirical evidence to assist in understanding the factors impacting on the experienced success of Muslim women. Additionally, strategies in the form of recommendations were advised with the aim of enhancing the experienced success of Muslim women. This study contributes to the body of knowledge relating to the advancement of Muslim women in the South African context. , Thesis (PhD) -- Faculty of Business and Economic Science, 2023
- Full Text:
- Date Issued: 2023-04
A business model framework for mission-driven organisations
- Authors: Thackeray, Sean Robin
- Date: 2023-03-31
- Subjects: Nonprofit organizations South Africa Makhanda , Business model , Sustainable development South Africa Makhanda , Resource-based view , Social responsibility of business South Africa Makhanda
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419123 , vital:71618
- Description: Non-profit organisations (NPOs) contribute to our society by addressing needs through value-creation activities which are normally not addressed by normal for-profit organisations. These NPOs generate their income through donations, fundraising and market activities such as the sale of products or services. However, in the pursuit of organisational sustainability, these NPOs need to ensure that their income meets their expenditure needs over the long run, to allow continuous value creation and to pursue their mission. An organisation’s business model can be visualised through a business model framework (BMF), which have been illustrated to be useful tools for organisations to test new business models, plan and coordinate activities, and to communicate how an organisations business model works to stakeholders. The use of BMFs by NPOs may be useful for similar purposes. However, a key challenge for NPOs and their management is adapting for-profit tools to be more applicable to the NPO environment. Whilst there has been some progress within the literature on adapting these for-profit business model tools to NPOs, this area of research is relatively underrepresented in the literature. The single case study method, exploratory in nature, following a deductive approach with a theoretical framework was used to evaluate the NPO Business model framework for NPOs with multiple income streams (Sanderse, 2014) appropriateness for the Centre for Biological Control (CBC), a mission-driven research organisation located within Rhodes University. The study made use of an interpretivist paradigm through the lens of resource-based theory. The contextual environment of the CBC was similar to other NPOs in that their organisational sustainability was at risk due to uncertainty about the availability of long-term funding. The CBC is actively diversifying their income streams by establishing new partnerships, which increase the capacity and resource base of the organisation to improve its flexibility in meeting current and potential funders’ needs. The NPO Business model framework for NPOs with multiple income streams was found to be a suitable BMF to visualise the holistic operations of the CBC. However, the role of governance-related matters being represented in this BMF was found to be lacking. An amended framework including governance as part of the Business model framework for NPOs with multiple income streams was developed. This improved the BMF, by allowing for further contextual insight into the CBCs business model as governance played a major role in the key activities and income-generating strategies they participate in. The role a BMF has in assisting an organisation with resource management activities was also explored. A suitable BMF, which allows for a holistic and explicit display of an organisation’s business model, would assist in determining how resources could be better managed or orchestrated to pursue different potential income-generating strategies or improve the efficiency of how resources are used in the current business model. This study contributed to business model theory by further testing the Business model framework for NPOs with multiple income streams as a tool to visualise an NPOs business model and identifying that once the governance block was added, this BMF became more suitable within the CBCs context. A minor contribution to resource based theory was the exploration of the potential roles BMFs play in resource management, which should be further investigated in line with additional research questions proposed. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Thackeray, Sean Robin
- Date: 2023-03-31
- Subjects: Nonprofit organizations South Africa Makhanda , Business model , Sustainable development South Africa Makhanda , Resource-based view , Social responsibility of business South Africa Makhanda
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419123 , vital:71618
- Description: Non-profit organisations (NPOs) contribute to our society by addressing needs through value-creation activities which are normally not addressed by normal for-profit organisations. These NPOs generate their income through donations, fundraising and market activities such as the sale of products or services. However, in the pursuit of organisational sustainability, these NPOs need to ensure that their income meets their expenditure needs over the long run, to allow continuous value creation and to pursue their mission. An organisation’s business model can be visualised through a business model framework (BMF), which have been illustrated to be useful tools for organisations to test new business models, plan and coordinate activities, and to communicate how an organisations business model works to stakeholders. The use of BMFs by NPOs may be useful for similar purposes. However, a key challenge for NPOs and their management is adapting for-profit tools to be more applicable to the NPO environment. Whilst there has been some progress within the literature on adapting these for-profit business model tools to NPOs, this area of research is relatively underrepresented in the literature. The single case study method, exploratory in nature, following a deductive approach with a theoretical framework was used to evaluate the NPO Business model framework for NPOs with multiple income streams (Sanderse, 2014) appropriateness for the Centre for Biological Control (CBC), a mission-driven research organisation located within Rhodes University. The study made use of an interpretivist paradigm through the lens of resource-based theory. The contextual environment of the CBC was similar to other NPOs in that their organisational sustainability was at risk due to uncertainty about the availability of long-term funding. The CBC is actively diversifying their income streams by establishing new partnerships, which increase the capacity and resource base of the organisation to improve its flexibility in meeting current and potential funders’ needs. The NPO Business model framework for NPOs with multiple income streams was found to be a suitable BMF to visualise the holistic operations of the CBC. However, the role of governance-related matters being represented in this BMF was found to be lacking. An amended framework including governance as part of the Business model framework for NPOs with multiple income streams was developed. This improved the BMF, by allowing for further contextual insight into the CBCs business model as governance played a major role in the key activities and income-generating strategies they participate in. The role a BMF has in assisting an organisation with resource management activities was also explored. A suitable BMF, which allows for a holistic and explicit display of an organisation’s business model, would assist in determining how resources could be better managed or orchestrated to pursue different potential income-generating strategies or improve the efficiency of how resources are used in the current business model. This study contributed to business model theory by further testing the Business model framework for NPOs with multiple income streams as a tool to visualise an NPOs business model and identifying that once the governance block was added, this BMF became more suitable within the CBCs context. A minor contribution to resource based theory was the exploration of the potential roles BMFs play in resource management, which should be further investigated in line with additional research questions proposed. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2023
- Full Text:
- Date Issued: 2023-03-31
A compliance framework for IT governance adoption and use by state-owned entities in South Africa
- Authors: Nxozi, Monelo
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/419244 , vital:71628
- Description: Embargoed. Possible release date in early 2025. , Thesis (PhD) -- Faculty of Commerce, Information Systems, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Nxozi, Monelo
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/419244 , vital:71628
- Description: Embargoed. Possible release date in early 2025. , Thesis (PhD) -- Faculty of Commerce, Information Systems, 2023
- Full Text:
- Date Issued: 2023-03-31
A native weevil and an exotic planthopper: investigating potential biological control agents for nymphaea mexicana zuccarini (nymphaeaceae) and its hybrids in South Africa
- Authors: Reid, Megan Kim
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422554 , vital:71957 , DOI 10.21504/10962/422554
- Description: Nymphaea mexicana Zuccarini (Nymphaeaceae) is an invasive plant originating from southern USA and Mexico that has become problematic in South Africa, invading several water bodies around the country. Manual removal of this plant is very labour intensive and is not cost efficient or effective for long term control, while the use of herbicides is damaging to the environment and expensive. Consequently, this plant is a desirable candidate for biological control, which takes advantage of enemy release of the target weed and aims to re-establish population suppression induced by host specific natural enemies. Initiating biological control requires that several steps are followed to maximise the success of the programme, and the first few of these, including overseas surveys in the native range of the plant, have already been completed. This thesis aimed to continue biological control research for this species to take further steps at effectively managing the plant. Firstly, pre-release surveys in the invaded range are necessary to: determine what factors (including enemy release) contribute to the invasiveness of the target weed; establish a baseline of information to allow for comparison after biological control agents have been released; and identify any insect herbivores that may already be present in the country. The pre-release surveys conducted in this study revealed useful information about N. mexicana invasions in South Africa and provided evidence that enemy release is applicable to this case. However, these studies determined that a native weevil, Bagous longulus Gyllenhal (Coleoptera: Curculionidae), has expanded its host range to include the exotic N. mexicana at three sites, and may thus have potential for management of the species through augmentative releases. The invasion of N. mexicana in South Africa is further complicated by the presence of several Nymphaea hybrids originating from a complex history of horticultural trade. Although previous research has shown that several hybrid groups are present in South Africa, their parentage is not known. As biological control requires the use of host specific insects adapted to overcome the unique chemical and morphological defences utilised by plant species, hybrids are notoriously difficult to manage because they possess intermediate characters inherited from parent species to which natural enemies may not have adapted. Although biological control of hybrids is challenging, other case studies have demonstrated that it is possible to find suitable agents, but the chances of success are increased if putative parents of the hybrids are known so that they can be surveyed for natural enemies. Further molecular studies including possible parents of the Nymphaea hybrids in South Africa were thus carried out in this thesis to focus future surveying efforts. Two main hybrid groups were identified with genetic similarity to two tested putative Nymphaea parents, and this will allow further investigations of these species to improve the chances of successfully managing these hybrid groups. Some of the tested hybrids showed genetic contributions from multiple groups, some of which were unidentified, so it is necessary to prioritise the most problematic hybrids for biological control. With more insight into the genetic makeup of the Nymphaea hybrids in South Africa, investigations into the host specificity of potential biological control agents can be conducted. The ideal biological control agent should have a broad enough host range to impact and survive on both N. mexicana and its hybrids, but without a host range so broad that it would pose risk to native South African species. Host specificity trials are thus necessary to determine the suitability of potential agents. The identification of B. longulus feeding on N. mexicana during pre-release surveys motivated further investigations to determine the natural distribution, field host range, and host specificity of B. longulus in experimentally controlled conditions. Further surveys were therefore conducted at native Nymphaea sites around South Africa in addition to host specificity trials using the native Nymphaea nouchali Burm. f. (Nymphaeaceae), two populations of N. mexicana, and a cultivated hybrid. Results from the surveys and host specificity tests suggest that B. longulus is widely distributed across South Africa, is specific to Nymphaea with no observed preference between N. mexicana and the native N. nouchali, and does not perform well on Nymphaea hybrids. Hence, B. longulus is promising for use in new association biological control through augmentative releases but is not suitable for management of hybrids. In addition to the potential use of the South African B. longulus, it is necessary to conduct host specificity trials for natural enemies from the native range of N. mexicana that were prioritised in previous studies. Megamelus toddi Beamer (Hemiptera: Delphacidae) is one such species that was imported into quarantined laboratory conditions from Florida, USA. Host specificity trials were conducted using the same test plants as described for the studies on B. longulus, in addition to multigeneration trials to determine how long M. toddi could survive on non-target host plants. As with the B. longulus studies, no statistically significant differences in preference were observed between N. mexicana and N. nouchali, but M. toddi could not complete development on the test hybrid, indicating that this species is also unsuitable for the management of Nymphaea hybrids. Despite suboptimal plant health, M. toddi completed development for three generations on the native N. nouchali. This lack of host specificity deems M. toddi unsafe for release in South Africa but highlights the importance of following predefined steps to develop a biological control programme. The concluding chapter of this thesis discusses the aforementioned findings in a broader context by considering the driving forces of plant invasions in general and specifically for N. mexicana in South Africa. Case studies are also consulted to provide insight into how to proceed with managing Nymphaea hybrids in South Africa, while the factors governing host specificity and host range expansion are also discussed and considered in the context of B. longulus and M. toddi. Finally, after a consideration of the limitations of these studies, recommendations are made to continue the development of biological control for N. mexicana in South Africa. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Reid, Megan Kim
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422554 , vital:71957 , DOI 10.21504/10962/422554
- Description: Nymphaea mexicana Zuccarini (Nymphaeaceae) is an invasive plant originating from southern USA and Mexico that has become problematic in South Africa, invading several water bodies around the country. Manual removal of this plant is very labour intensive and is not cost efficient or effective for long term control, while the use of herbicides is damaging to the environment and expensive. Consequently, this plant is a desirable candidate for biological control, which takes advantage of enemy release of the target weed and aims to re-establish population suppression induced by host specific natural enemies. Initiating biological control requires that several steps are followed to maximise the success of the programme, and the first few of these, including overseas surveys in the native range of the plant, have already been completed. This thesis aimed to continue biological control research for this species to take further steps at effectively managing the plant. Firstly, pre-release surveys in the invaded range are necessary to: determine what factors (including enemy release) contribute to the invasiveness of the target weed; establish a baseline of information to allow for comparison after biological control agents have been released; and identify any insect herbivores that may already be present in the country. The pre-release surveys conducted in this study revealed useful information about N. mexicana invasions in South Africa and provided evidence that enemy release is applicable to this case. However, these studies determined that a native weevil, Bagous longulus Gyllenhal (Coleoptera: Curculionidae), has expanded its host range to include the exotic N. mexicana at three sites, and may thus have potential for management of the species through augmentative releases. The invasion of N. mexicana in South Africa is further complicated by the presence of several Nymphaea hybrids originating from a complex history of horticultural trade. Although previous research has shown that several hybrid groups are present in South Africa, their parentage is not known. As biological control requires the use of host specific insects adapted to overcome the unique chemical and morphological defences utilised by plant species, hybrids are notoriously difficult to manage because they possess intermediate characters inherited from parent species to which natural enemies may not have adapted. Although biological control of hybrids is challenging, other case studies have demonstrated that it is possible to find suitable agents, but the chances of success are increased if putative parents of the hybrids are known so that they can be surveyed for natural enemies. Further molecular studies including possible parents of the Nymphaea hybrids in South Africa were thus carried out in this thesis to focus future surveying efforts. Two main hybrid groups were identified with genetic similarity to two tested putative Nymphaea parents, and this will allow further investigations of these species to improve the chances of successfully managing these hybrid groups. Some of the tested hybrids showed genetic contributions from multiple groups, some of which were unidentified, so it is necessary to prioritise the most problematic hybrids for biological control. With more insight into the genetic makeup of the Nymphaea hybrids in South Africa, investigations into the host specificity of potential biological control agents can be conducted. The ideal biological control agent should have a broad enough host range to impact and survive on both N. mexicana and its hybrids, but without a host range so broad that it would pose risk to native South African species. Host specificity trials are thus necessary to determine the suitability of potential agents. The identification of B. longulus feeding on N. mexicana during pre-release surveys motivated further investigations to determine the natural distribution, field host range, and host specificity of B. longulus in experimentally controlled conditions. Further surveys were therefore conducted at native Nymphaea sites around South Africa in addition to host specificity trials using the native Nymphaea nouchali Burm. f. (Nymphaeaceae), two populations of N. mexicana, and a cultivated hybrid. Results from the surveys and host specificity tests suggest that B. longulus is widely distributed across South Africa, is specific to Nymphaea with no observed preference between N. mexicana and the native N. nouchali, and does not perform well on Nymphaea hybrids. Hence, B. longulus is promising for use in new association biological control through augmentative releases but is not suitable for management of hybrids. In addition to the potential use of the South African B. longulus, it is necessary to conduct host specificity trials for natural enemies from the native range of N. mexicana that were prioritised in previous studies. Megamelus toddi Beamer (Hemiptera: Delphacidae) is one such species that was imported into quarantined laboratory conditions from Florida, USA. Host specificity trials were conducted using the same test plants as described for the studies on B. longulus, in addition to multigeneration trials to determine how long M. toddi could survive on non-target host plants. As with the B. longulus studies, no statistically significant differences in preference were observed between N. mexicana and N. nouchali, but M. toddi could not complete development on the test hybrid, indicating that this species is also unsuitable for the management of Nymphaea hybrids. Despite suboptimal plant health, M. toddi completed development for three generations on the native N. nouchali. This lack of host specificity deems M. toddi unsafe for release in South Africa but highlights the importance of following predefined steps to develop a biological control programme. The concluding chapter of this thesis discusses the aforementioned findings in a broader context by considering the driving forces of plant invasions in general and specifically for N. mexicana in South Africa. Case studies are also consulted to provide insight into how to proceed with managing Nymphaea hybrids in South Africa, while the factors governing host specificity and host range expansion are also discussed and considered in the context of B. longulus and M. toddi. Finally, after a consideration of the limitations of these studies, recommendations are made to continue the development of biological control for N. mexicana in South Africa. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2023
- Full Text:
- Date Issued: 2023-03-31
A statistical study of travelling ionospheric disturbances over the African-European and American sectors
- Authors: Thaganyana, Golekamang Piet
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422541 , vital:71956 , DOI 10.21504/10962/422543
- Description: This research presents a long-term statistical study of travelling ionospheric disturbances (TIDs) of low- and high-latitude origin over the American and African-European sectors between 2010 and 2018. The TIDs of low latitude origin (hereafter known as poleward TIDs) were studied in both quiet and disturbed conditions, whereas the equatorward TIDs were only studied during quiet conditions. The Kp > 4 and Dst_ -50 nT was used as a criterion for geomagnetic disturbed conditions, while the four geomagnetically quiet days were selected each month based on Kp < 3. Observations of TIDs are made using Global Navigational Satellite Systems (GNSS) total electron content derived data. During quiet conditions, seven and two transhemispheric TIDs were identified over the African-European and American sectors, respectively. The observed TIDs originated from the wintertime hemisphere and propagated into the summertime hemisphere. The horizontal velocity, periods, and horizontal wavelengths of TIDs are in range of cH = 120-274 m/s, 48-80 min and _H = 379-1104 km, respectively. These quiet-time equatorward TIDs have been associated with tertiary gravity waves (GWs) from the dissipation of secondary GWs which are in turn generated from the dissipation of mountain waves (MWs) as a result of excited orographic forcing. The poleward TIDs during geomagnetically quiet conditions over the African and American sectors occur mainly during local daytime. Poleward TIDs were observed mostly in the African-European sector than the American sector. Their horizontal propagation velocities and periods range between 129-280 m/s and 39-70 min over African-European and American sectors. Although the mechanisms responsible for launching quiet-time poleward TIDs have not been established in this study, lower atmospheric processes such as convection systems, sudden stratospheric warming and cold weather fronts may have a role in their generation. During geomagnetic storms in the African sector, almost all poleward TIDs (with the exception of two cases) during the main phase were large-scale with horizontal velocities and periods ranging from 250-503 m/s and 30 min to 2 hours. During recovery phase, poleward TIDs fall under the category of medium scale. In the American sector, the majority of poleward TIDs occurred during the storm's main phase, as opposed to the African-European sector, which experienced a significant number of poleward TIDs during the recovery phase. The periods and horizontal velocities of TIDs range from 45 min-1.5 h and 180-296 m/s during main phase. During the recovery phase, the horizontal velocity and period range from 177-271 m/s and 40-1.5 h, respectively. Overall, it has been shown that statistically, changes in equatorial electrodynamics related to enhanced eastward electric _eld and hence increased equatorial electrojet (vertical E_B drift) correlates highly with the reported poleward TIDs. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Thaganyana, Golekamang Piet
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422541 , vital:71956 , DOI 10.21504/10962/422543
- Description: This research presents a long-term statistical study of travelling ionospheric disturbances (TIDs) of low- and high-latitude origin over the American and African-European sectors between 2010 and 2018. The TIDs of low latitude origin (hereafter known as poleward TIDs) were studied in both quiet and disturbed conditions, whereas the equatorward TIDs were only studied during quiet conditions. The Kp > 4 and Dst_ -50 nT was used as a criterion for geomagnetic disturbed conditions, while the four geomagnetically quiet days were selected each month based on Kp < 3. Observations of TIDs are made using Global Navigational Satellite Systems (GNSS) total electron content derived data. During quiet conditions, seven and two transhemispheric TIDs were identified over the African-European and American sectors, respectively. The observed TIDs originated from the wintertime hemisphere and propagated into the summertime hemisphere. The horizontal velocity, periods, and horizontal wavelengths of TIDs are in range of cH = 120-274 m/s, 48-80 min and _H = 379-1104 km, respectively. These quiet-time equatorward TIDs have been associated with tertiary gravity waves (GWs) from the dissipation of secondary GWs which are in turn generated from the dissipation of mountain waves (MWs) as a result of excited orographic forcing. The poleward TIDs during geomagnetically quiet conditions over the African and American sectors occur mainly during local daytime. Poleward TIDs were observed mostly in the African-European sector than the American sector. Their horizontal propagation velocities and periods range between 129-280 m/s and 39-70 min over African-European and American sectors. Although the mechanisms responsible for launching quiet-time poleward TIDs have not been established in this study, lower atmospheric processes such as convection systems, sudden stratospheric warming and cold weather fronts may have a role in their generation. During geomagnetic storms in the African sector, almost all poleward TIDs (with the exception of two cases) during the main phase were large-scale with horizontal velocities and periods ranging from 250-503 m/s and 30 min to 2 hours. During recovery phase, poleward TIDs fall under the category of medium scale. In the American sector, the majority of poleward TIDs occurred during the storm's main phase, as opposed to the African-European sector, which experienced a significant number of poleward TIDs during the recovery phase. The periods and horizontal velocities of TIDs range from 45 min-1.5 h and 180-296 m/s during main phase. During the recovery phase, the horizontal velocity and period range from 177-271 m/s and 40-1.5 h, respectively. Overall, it has been shown that statistically, changes in equatorial electrodynamics related to enhanced eastward electric _eld and hence increased equatorial electrojet (vertical E_B drift) correlates highly with the reported poleward TIDs. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2023
- Full Text:
- Date Issued: 2023-03-31
An analysis of integrated reporting on the governance of selected State-Owned Enterprises (SOEs)
- Authors: Songxaba, Bathabile Liberty
- Date: 2023-03-31
- Subjects: Government business enterprises Management , Integrated reporting , Integrative thinking , Corporate governance Law and legislation South Africa , Good governance , Business ethics South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419112 , vital:71617
- Description: The research investigated how integrated annual reports (IARs) can enhance the governance of state-owned enterprises (SOEs). Governance of SOEs is crucial to achieving the county’s socio-economic objectives. The SOEs listed on Schedule 2 of the Performance Finance Management Act (PFMA), Act No. No.1 of 1999, as amended in March 2017, represents, among many, the electricity, transportation, and telecommunication sectors. This study analysed the integrated reporting (IR) governance of selected schedule 2 of PFMA SOEs. The researcher adopted the qualitative approach for the study. Firstly, the analysis was to identify and describe the governance disclosures as evident in IARs using the King IV principles. Secondly, the study analysed the reporting trends associated with governance practices over 2018 – 2020. Integrated reports from Eskom, Transnet, and Telkom were selected for three years. Relevant concepts discussed in the literature review include corporate governance, King reports on corporate governance, King IV principles, the principle of materiality on governance disclosures, corporate reporting, integrated reporting, integrated thinking, benefits of integrated reporting, theoretical underpinnings of the study, and a conclusion. The disclosures were summarised per year and SOE per King IV principle, resulting in nine (9) excel spreadsheets, which were combined excel spreadsheets sorted into a logical structure based on coding to keep track of the source data sequence. The data was systematically manually coded using Ose's (2016) Microsoft Word and Excel method. Findings included seven themes which were ethics, irregular expenditure, internal controls, accountability, governance structures, reputation, and sustainability. Themes were transferred to subtopics for comparative analysis to assess trends and the SOEs’ governance disclosures. The results found that all three SOEs have disclosed using King IV principles guided by the 2013 International Integrated Reporting Council’s (IIRC) framework. All SOEs disclosed their governance in their reports and practice explained. There are noticeable differences, Eskom and Transnet are solely government-owned, and Telkom is partially privatised and run privately as the majority holding is mostly private. Eskom and Transnet reflected more similarities in terms of their operational and financial challenges, whereas Telkom operates in a more competitive environment and is run as a private company which is portrayed to be profitable and restricted to Johannesburg Stock Exchange (JSE) requirements. Disclosures indicate progress on material matters and links associated with functional areas such as strategy and risks. Materiality is a guiding principle in the IIRC framework, which assist discloses information that significantly affects the organisation’s ability to create value over time. The similarities in all three SOEs include challenges in retaining competent and ethical leaders, which is critical for enhancing good governance. The study recommended how the integrated report can be viewed as a management and accounting tool for the governing body and stakeholders to focus on drivers that create value and consider drivers that erode or preserve value. This feedback may assist in informing strategy, business model, and decision-making for the governing body to set governing structures that support the organisation to create sustained value. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Songxaba, Bathabile Liberty
- Date: 2023-03-31
- Subjects: Government business enterprises Management , Integrated reporting , Integrative thinking , Corporate governance Law and legislation South Africa , Good governance , Business ethics South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419112 , vital:71617
- Description: The research investigated how integrated annual reports (IARs) can enhance the governance of state-owned enterprises (SOEs). Governance of SOEs is crucial to achieving the county’s socio-economic objectives. The SOEs listed on Schedule 2 of the Performance Finance Management Act (PFMA), Act No. No.1 of 1999, as amended in March 2017, represents, among many, the electricity, transportation, and telecommunication sectors. This study analysed the integrated reporting (IR) governance of selected schedule 2 of PFMA SOEs. The researcher adopted the qualitative approach for the study. Firstly, the analysis was to identify and describe the governance disclosures as evident in IARs using the King IV principles. Secondly, the study analysed the reporting trends associated with governance practices over 2018 – 2020. Integrated reports from Eskom, Transnet, and Telkom were selected for three years. Relevant concepts discussed in the literature review include corporate governance, King reports on corporate governance, King IV principles, the principle of materiality on governance disclosures, corporate reporting, integrated reporting, integrated thinking, benefits of integrated reporting, theoretical underpinnings of the study, and a conclusion. The disclosures were summarised per year and SOE per King IV principle, resulting in nine (9) excel spreadsheets, which were combined excel spreadsheets sorted into a logical structure based on coding to keep track of the source data sequence. The data was systematically manually coded using Ose's (2016) Microsoft Word and Excel method. Findings included seven themes which were ethics, irregular expenditure, internal controls, accountability, governance structures, reputation, and sustainability. Themes were transferred to subtopics for comparative analysis to assess trends and the SOEs’ governance disclosures. The results found that all three SOEs have disclosed using King IV principles guided by the 2013 International Integrated Reporting Council’s (IIRC) framework. All SOEs disclosed their governance in their reports and practice explained. There are noticeable differences, Eskom and Transnet are solely government-owned, and Telkom is partially privatised and run privately as the majority holding is mostly private. Eskom and Transnet reflected more similarities in terms of their operational and financial challenges, whereas Telkom operates in a more competitive environment and is run as a private company which is portrayed to be profitable and restricted to Johannesburg Stock Exchange (JSE) requirements. Disclosures indicate progress on material matters and links associated with functional areas such as strategy and risks. Materiality is a guiding principle in the IIRC framework, which assist discloses information that significantly affects the organisation’s ability to create value over time. The similarities in all three SOEs include challenges in retaining competent and ethical leaders, which is critical for enhancing good governance. The study recommended how the integrated report can be viewed as a management and accounting tool for the governing body and stakeholders to focus on drivers that create value and consider drivers that erode or preserve value. This feedback may assist in informing strategy, business model, and decision-making for the governing body to set governing structures that support the organisation to create sustained value. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2023
- Full Text:
- Date Issued: 2023-03-31
An analysis of the interpretation and application of anti-tax avoidance legislation in the Income Tax Act, 58 of 1962 (as amended)
- Denhere, Munyaradzi Blessing
- Authors: Denhere, Munyaradzi Blessing
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419436 , vital:71644
- Description: Assessed losses provide opportunities to avoid taxation by using various arrangements or transactions. Legislation has been introduced to combat these forms of tax avoidance, in the form of sections 20, 20A, 103(2) and 103(4), and sections 80A to 80L. These sections have also frequently been considered by the courts. The research problem was therefore the analysis of the interaction and effect of the provisions in the Income Tax Act dealing with the use of assessed losses for the purpose of tax avoidance, and the case law interpretation of these provisions. The main goal of the research was to critically analyse the scope and effect of sections 20, 20A, and 103(2) and 102(4), and sections 80A to 80L of the Income Tax Act, dealing with assessed losses, together with the interpretation by the courts. The research was situated within the interpretative paradigm, adopted a qualitative approach, with a doctrinal methodology. As the research was carried out using only publicly available documents, no ethical considerations applied. In addressing the goal of the research, the thesis first discussed the concept of tax avoidance and its consequences. The two main interpretative approaches adopted by the courts, including with regard to tax provisions – the strict literal and the purposive approaches – were described. The thesis then proceeded to analyse sections 20, 20A, 103(2) and 103(4), and sections 80A to 80L, together with the relevant case law, and in the case of sections 80A to 80L, with the use of a hypothetical example, to illustrate the application of the sections. The conclusion arrived at was that the sections discussed in the thesis are adequate to address the problem of the misuse of assessed losses to avoid tax. , Thesis (MCom) -- Faculty of Commerce, Accounting, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Denhere, Munyaradzi Blessing
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419436 , vital:71644
- Description: Assessed losses provide opportunities to avoid taxation by using various arrangements or transactions. Legislation has been introduced to combat these forms of tax avoidance, in the form of sections 20, 20A, 103(2) and 103(4), and sections 80A to 80L. These sections have also frequently been considered by the courts. The research problem was therefore the analysis of the interaction and effect of the provisions in the Income Tax Act dealing with the use of assessed losses for the purpose of tax avoidance, and the case law interpretation of these provisions. The main goal of the research was to critically analyse the scope and effect of sections 20, 20A, and 103(2) and 102(4), and sections 80A to 80L of the Income Tax Act, dealing with assessed losses, together with the interpretation by the courts. The research was situated within the interpretative paradigm, adopted a qualitative approach, with a doctrinal methodology. As the research was carried out using only publicly available documents, no ethical considerations applied. In addressing the goal of the research, the thesis first discussed the concept of tax avoidance and its consequences. The two main interpretative approaches adopted by the courts, including with regard to tax provisions – the strict literal and the purposive approaches – were described. The thesis then proceeded to analyse sections 20, 20A, 103(2) and 103(4), and sections 80A to 80L, together with the relevant case law, and in the case of sections 80A to 80L, with the use of a hypothetical example, to illustrate the application of the sections. The conclusion arrived at was that the sections discussed in the thesis are adequate to address the problem of the misuse of assessed losses to avoid tax. , Thesis (MCom) -- Faculty of Commerce, Accounting, 2023
- Full Text:
- Date Issued: 2023-03-31
An empirical analysis of the interplay among bank competition, bank stability and regulation: a case study of banks in Zimbabwe
- Nyamuronda, Gracious Varayidzo
- Authors: Nyamuronda, Gracious Varayidzo
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419473 , vital:71647
- Description: This study empirically examined the interconnection among bank competition, regulation and stability of eighteen Zimbabwean banks during the period 2011-2017. Zscore, Capital Adequacy Ratio (CAD), and Loans market share and Deposits market share which are proxies for stability, regulation and competition respectively were examined firstly using the Panel Vector Autoregressive (PVAR) model. Model 1 used loans market share as a proxy for competition and model 2 used deposits market share instead. The stability test using Eigenvalue Stability Condition showed that the PVAR model is unstable. Secondly, the above variables and five bank specific variables (i.e., credit risk, management efficiency, liquidity, return on assets and bank size) were estimated using the Feasible Generalised Least Squares (FGLS) model. The study documents that competition positively contributed to stability and regulation negatively influenced the stability of the Zimbabwean banks. Meanwhile, bank size and credit risk have a negative relationship with stability; management efficiency and liquidity have a positive relationship. Return On Assets has a negative and positive relationship with stability in model 1 and model 2, respectively. The findings implied that to enhance stability, banks must experience a competitive environment, reasonably low minimum capital requirements and cautiously designed regulatory frameworks. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Nyamuronda, Gracious Varayidzo
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419473 , vital:71647
- Description: This study empirically examined the interconnection among bank competition, regulation and stability of eighteen Zimbabwean banks during the period 2011-2017. Zscore, Capital Adequacy Ratio (CAD), and Loans market share and Deposits market share which are proxies for stability, regulation and competition respectively were examined firstly using the Panel Vector Autoregressive (PVAR) model. Model 1 used loans market share as a proxy for competition and model 2 used deposits market share instead. The stability test using Eigenvalue Stability Condition showed that the PVAR model is unstable. Secondly, the above variables and five bank specific variables (i.e., credit risk, management efficiency, liquidity, return on assets and bank size) were estimated using the Feasible Generalised Least Squares (FGLS) model. The study documents that competition positively contributed to stability and regulation negatively influenced the stability of the Zimbabwean banks. Meanwhile, bank size and credit risk have a negative relationship with stability; management efficiency and liquidity have a positive relationship. Return On Assets has a negative and positive relationship with stability in model 1 and model 2, respectively. The findings implied that to enhance stability, banks must experience a competitive environment, reasonably low minimum capital requirements and cautiously designed regulatory frameworks. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2023
- Full Text:
- Date Issued: 2023-03-31
Characterization of Trypanosoma brucei Sti1 and its interactions with Trypanosoma brucei Hsp83 and human Hsp90
- Authors: Jamabo, Miebaka
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422629 , vital:71963 , DOI 10.21504/10962/422629
- Description: Neglected tropical diseases continue to pose global concern due to their impact on health and socio-economic status of developing countries in sub-Saharan Africa. African trypanosomiasis is one of the neglected tropical diseases caused by the kinetoplastid flagellate parasite Trypanosoma brucei (T. brucei). The disease is fatal if untreated and the toolbox to combat the disease has been plagued with many difficulties such as drug resistance, toxic chemotherapeutics, and cumbersome drug delivery processes. In recent years, the disease has received attention from organizations such as the Drugs for Neglected Diseases initiative (DNDi) in partnership with WHO as well as academia and industry to provide alternatives to the existing drugs as part of a targeted approach to eliminate human African trypanosomiasis by 2030. The life cycle of the T. brucei parasite requires that it transitions between a cold-blooded vector (the tsetse fly) and a human host. To survive this extreme environmental change and maintain its infectious cycle, the parasite has evolved an arsenal of tools which include a strong immune evasion technique and a robust molecular chaperone system. Heat shock protein 90 (Hsp90) is one of the most abundant eukaryotic molecular chaperones that has been extensively studied in many organisms. It is indispensable for maintaining proteostasis in some organisms and its inhibition is currently being explored as a drug target for cancer and other parasitic diseases. In T. brucei, cytosolic Hsp90 is specifically referred to as Hsp83 due to variations in the sizes amongst different orthologues. Hsp90 is present in high levels in all stages of the T. brucei cell cycle both constitutively and on exposure to stress. To function in the cell, Hsp90 is dependent on co-chaperones, one of which can be found in most organisms, namely, the stress-inducible protein 1 (Sti1). The Hsp90-Sti1 interaction was shown to be crucial for growth in the intracellular kinetoplastid parasite, Leishmania donovani. However, this partnership has not been explored in the extracellular parasite T. brucei. To analyse the interaction of Hsp90 with Sti1 in T. brucei, this study combined in silico, in vitro and in vivo tools. In silico analyses of the Hsp90 complement in T. brucei revealed the presence of twelve putative Hsp90 genes, ten of which code for the cytosolic protein and are arranged in tandem in a head to tail fashion on the same chromosome. One gene each was found for the mitochondrial and ER paralogues of Hsp90, similar to all other species analysed. Eight putative co-chaperones specific to T. brucei were also discovered: six tetratricopeptide repeat domain (TPR) containing co-chaperones and two non-TPR containing co-chaperones. Structural and evolutionary analysis also confirmed that the domains were conserved across the species analysed. T. brucei Sti1 (TbSti1), T. brucei cytosolic Hsp90 (TbHsp83) and human cytosolic Hsp90 (hHsp90) were heterologously overproduced in E. coli and purified using nickel affinity chromatography. With specific antibodies, the expression and localization of the proteins were confirmed. TbSti1 showed strong affinity to the Hsp90s in the nanomolar range, with higher affinity for hHsp90 compared to TbHsp83. TbHsp83 and hHsp90 showed typical chaperone properties by suppressing the aggregation of thermolabile substrate MDH at equimolar concentrations and both chaperones had potent ATP hydrolysis activity. TbSti1, on the other hand, showed no MDH suppression activity and did not affect the ATP hydrolysis activity of TbHsp83 or hHsp90. Ex-vivo experiments using HeLa CRISPR Hop knockout (KO) human cell lines transfected with pcDNA3.1(+)HA-TbSti1 revealed TbSti1 also localized to the cytoplasm. The transfected cells showed a distinct fibroblast-like morphology which was different from the circular morphology seen in the Hop KO untransfected and wild type untransfected cells. Finally, co-immunoprecipitation studies revealed that TbSti1 co-immunoprecipitated with hHsp90. These results show the first characterization of the TbHsp83-TbSti1 partnership in T. brucei. The strong association between both proteins suggests a functional role for this partnership in T. brucei and could provide an updated context for understanding Trypanosome brucei biology. , Thesis (PhD) -- Faculty of Science, Biotechnology and Innovation Centre, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Jamabo, Miebaka
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422629 , vital:71963 , DOI 10.21504/10962/422629
- Description: Neglected tropical diseases continue to pose global concern due to their impact on health and socio-economic status of developing countries in sub-Saharan Africa. African trypanosomiasis is one of the neglected tropical diseases caused by the kinetoplastid flagellate parasite Trypanosoma brucei (T. brucei). The disease is fatal if untreated and the toolbox to combat the disease has been plagued with many difficulties such as drug resistance, toxic chemotherapeutics, and cumbersome drug delivery processes. In recent years, the disease has received attention from organizations such as the Drugs for Neglected Diseases initiative (DNDi) in partnership with WHO as well as academia and industry to provide alternatives to the existing drugs as part of a targeted approach to eliminate human African trypanosomiasis by 2030. The life cycle of the T. brucei parasite requires that it transitions between a cold-blooded vector (the tsetse fly) and a human host. To survive this extreme environmental change and maintain its infectious cycle, the parasite has evolved an arsenal of tools which include a strong immune evasion technique and a robust molecular chaperone system. Heat shock protein 90 (Hsp90) is one of the most abundant eukaryotic molecular chaperones that has been extensively studied in many organisms. It is indispensable for maintaining proteostasis in some organisms and its inhibition is currently being explored as a drug target for cancer and other parasitic diseases. In T. brucei, cytosolic Hsp90 is specifically referred to as Hsp83 due to variations in the sizes amongst different orthologues. Hsp90 is present in high levels in all stages of the T. brucei cell cycle both constitutively and on exposure to stress. To function in the cell, Hsp90 is dependent on co-chaperones, one of which can be found in most organisms, namely, the stress-inducible protein 1 (Sti1). The Hsp90-Sti1 interaction was shown to be crucial for growth in the intracellular kinetoplastid parasite, Leishmania donovani. However, this partnership has not been explored in the extracellular parasite T. brucei. To analyse the interaction of Hsp90 with Sti1 in T. brucei, this study combined in silico, in vitro and in vivo tools. In silico analyses of the Hsp90 complement in T. brucei revealed the presence of twelve putative Hsp90 genes, ten of which code for the cytosolic protein and are arranged in tandem in a head to tail fashion on the same chromosome. One gene each was found for the mitochondrial and ER paralogues of Hsp90, similar to all other species analysed. Eight putative co-chaperones specific to T. brucei were also discovered: six tetratricopeptide repeat domain (TPR) containing co-chaperones and two non-TPR containing co-chaperones. Structural and evolutionary analysis also confirmed that the domains were conserved across the species analysed. T. brucei Sti1 (TbSti1), T. brucei cytosolic Hsp90 (TbHsp83) and human cytosolic Hsp90 (hHsp90) were heterologously overproduced in E. coli and purified using nickel affinity chromatography. With specific antibodies, the expression and localization of the proteins were confirmed. TbSti1 showed strong affinity to the Hsp90s in the nanomolar range, with higher affinity for hHsp90 compared to TbHsp83. TbHsp83 and hHsp90 showed typical chaperone properties by suppressing the aggregation of thermolabile substrate MDH at equimolar concentrations and both chaperones had potent ATP hydrolysis activity. TbSti1, on the other hand, showed no MDH suppression activity and did not affect the ATP hydrolysis activity of TbHsp83 or hHsp90. Ex-vivo experiments using HeLa CRISPR Hop knockout (KO) human cell lines transfected with pcDNA3.1(+)HA-TbSti1 revealed TbSti1 also localized to the cytoplasm. The transfected cells showed a distinct fibroblast-like morphology which was different from the circular morphology seen in the Hop KO untransfected and wild type untransfected cells. Finally, co-immunoprecipitation studies revealed that TbSti1 co-immunoprecipitated with hHsp90. These results show the first characterization of the TbHsp83-TbSti1 partnership in T. brucei. The strong association between both proteins suggests a functional role for this partnership in T. brucei and could provide an updated context for understanding Trypanosome brucei biology. , Thesis (PhD) -- Faculty of Science, Biotechnology and Innovation Centre, 2023
- Full Text:
- Date Issued: 2023-03-31
Drive for show: putt for dough? The value of performance measures for professional golfers on the sunshine tour and the relationship with earnings
- Authors: Heathfield, Cameron Spencer
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419499 , vital:71649
- Description: “Drive for show, putt for dough”. This controversial adage has been a prominent sentiment in the game of golf for decades. Empirical evidence investigating its robustness through determinant of earnings inquiries have identified that the most valuable measure of performance in golf is in fact putting. However, with the ever-perpetuating state of golf equipment and the technologies thereof, the distance debate in golf has thus gained traction. Recent investigations and evidence into the adage had identified a trend-shift with regards to the value associated with distance achievable and putting ability in golf. Therefore questioning the relevance of the adage in the modern form of the game. In conducting a determinant of earnings inquiry through the engagement of engineering “pure” performance measures as empirically identified, this investigation is aimed at recognising a similar trend in a South African perspective, on the Sunshine Tour. Utilising a generalised least square regression methodology, the analysis identifies how the value of the marginal product as-sociated with both player and non-player explanatory measures influence real earnings on the Sun-shine Tour. This determination is observed through the means of a comprehensive scenario analysis, demonstrating the effect of marginal performance differences to the degree of 1% and 5% increase in performance. A trend was therefore identified in which the value of the marginal product, and growth in real earnings associated to driving distance at the 5% level were in fact greater than the that of putting ability. The results further denote the robustness of the adage and the inherent value associated to putting vs. driving distance at the 1% level. The conclusion to this investigation demonstrates the importance of opportunistic positions player’s put themselves in within tournaments to encourage earnings accumulation. Identified through balanced return on investments for all performance measures to “drive for dough to putt for dough”. , Thesis (MEcon) -- Faculty of Commerce, Economics and Economics History, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Heathfield, Cameron Spencer
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419499 , vital:71649
- Description: “Drive for show, putt for dough”. This controversial adage has been a prominent sentiment in the game of golf for decades. Empirical evidence investigating its robustness through determinant of earnings inquiries have identified that the most valuable measure of performance in golf is in fact putting. However, with the ever-perpetuating state of golf equipment and the technologies thereof, the distance debate in golf has thus gained traction. Recent investigations and evidence into the adage had identified a trend-shift with regards to the value associated with distance achievable and putting ability in golf. Therefore questioning the relevance of the adage in the modern form of the game. In conducting a determinant of earnings inquiry through the engagement of engineering “pure” performance measures as empirically identified, this investigation is aimed at recognising a similar trend in a South African perspective, on the Sunshine Tour. Utilising a generalised least square regression methodology, the analysis identifies how the value of the marginal product as-sociated with both player and non-player explanatory measures influence real earnings on the Sun-shine Tour. This determination is observed through the means of a comprehensive scenario analysis, demonstrating the effect of marginal performance differences to the degree of 1% and 5% increase in performance. A trend was therefore identified in which the value of the marginal product, and growth in real earnings associated to driving distance at the 5% level were in fact greater than the that of putting ability. The results further denote the robustness of the adage and the inherent value associated to putting vs. driving distance at the 1% level. The conclusion to this investigation demonstrates the importance of opportunistic positions player’s put themselves in within tournaments to encourage earnings accumulation. Identified through balanced return on investments for all performance measures to “drive for dough to putt for dough”. , Thesis (MEcon) -- Faculty of Commerce, Economics and Economics History, 2023
- Full Text:
- Date Issued: 2023-03-31
Economically important cephalopods of southern Angola, with a focus on the artisanal jig fishery
- Vázquez Morán, Chénelle Lesley
- Authors: Vázquez Morán, Chénelle Lesley
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422529 , vital:71955 , DOI 10.21504/10962/422529
- Description: The global decline in marine finfish stocks has been met with a concomitant expansion of fisheries for cephalopods. Despite the increase in the exploitation and commercialization of cephalopods, there is a dearth of scientific information for over 90% of the extant species and this is even more marked in the developing world. Angolan capture fisheries production noted a tenfold increase in cephalopod landings between 1994 and 2003. One of the important fisheries is a cephalopod directed jig fishery that targets the squid Loligo reynaudii and the cuttlefish Sepia vermiculata in southern Angola, however, there is a complete lack of socio-ecological information available for this fishery. Hence the aim of this thesis was to provide basic biological and demographic information on L. reynaudii and S. vermiculata distributed off the coast of southern Angola, assess the importance and dependence of local artisanal fishers on these two species and examine the current management strategies and policies in the region This study found that the artisanal cephalopod jig fishery is critical for the livelihoods of the coastal communities of southern Angola, particularly due to the limited alternative income generating opportunities available. The cephalopod jig fishery is highly labour intensive, with fishers spending a considerable amount of time per day, drifting over known fishing grounds. Catch composition of the artisanal jig fishery indicated that squid is the dominant species within the fishery, in terms of numerical abundance and weight. The productivity and progression of the fishery is hampered by a number of ecological, socio-economic and governance constraints, as highlighted by socio-economic surveys conducted with local squid fishers. Such constraints include, but are not limited to declining catches, increased negative interactions with seals, increased inter-sector competition, lack of infrastructure, poor quality fishing equipment as well as a lack of communication and support from government officials. To examine aspects of the biology and demography of L. reynaudii, whole specimens were collected monthly, from the two primary fishing areas in southern Angola; Namibe and Tombua, during two main sampling periods, June 2008 – May 2009 (Period 1) and June 2014 – May 2015 (Period 2). Male L. reynaudii were found to be significantly larger in size and weight than females, however both the average and maximum dorsal mantle length (DML) decreased between sampling periods. Length-at-50% maturity was larger for male L. reynaudii (170.47 mm DML – 1st period, 165.44 mm DML – 2nd period) than female L. reynaudii (114.71 mm DML – 1st period, 109.43 mm DML – 2nd period). Gonadosomatic indices (GSI) varied significantly during month and season for both sexes. Peak GSI coincided with a low catches in the artisanal jig fishery suggesting that the population may undergo a spawning migration away from fishing grounds, during late spring and summer. The theory of a seasonal spawning migration is further supported in this study by the low abundance of juvenile and sub-adult L, reynaudii collected during the study, along with the inability to detect egg beds in known fishing grounds. Stomach content analysis indicated that teleosts were the most important dietary item (66.3% F of the stomach contents). Trachurus capensis and Engraulis encrasicolus are both highly abundant small pelagic fishes in the cold nutrient rich waters of the Benguela Current and dominated the diet of sampled squid during autumn and winter months. It is likely that the prevalence of large, adult squid off the coast of Angola, as observed within the current study, may be ascribed to the suitable environmental conditions and the abundance of suitable prey. The results from the current study indicate that the southern Angolan subpopulation reveals similarities to that of the West Coast subpopulation of squid in South Africa, with regards to demographics and reproductive characteristics. It is likely that the population in southern Angola is an extension of the South African subpopulation of L. reynaudii on the western extremities. To examine the basic population biology and ecology of S. vermiculata off southern Angola whole specimens were collected from the fishery between December 2014 and April 2015. Morphological results indicate clear sexual dimorphism in soft part characteristics, cuttlebone and beak morphometry. Length-at-50% maturity was smaller in male S. vermiculata (217.53 mm DML) than female S. vermiculata (231.13 mm DML), although these differences were not significant. Stomach content analysis indicated that S. vermiculata predominantly fed on teleost species which were found within 64.5% of stomachs. Teleosts were more dominant in the diet of male S. vermiculata (78.6% F) than female S. vermiculata (53.0% F), which ate a more varied diet including crustaceans (41.2% F) and cephalopods (17.7% F). Availability and abundance of cuttlefish in Namibe indicates that the species may undergo a spatio-temporal shift in distribution, with majority of the artisanal catches of S. vermiculata occurring during summer months. The results from the current study highlights the fisheries potential of L. reynaudii and S. vermiculata and the dependence of artisanal fishers in southern Angola on cephalopods, and more specifically squid. The development of sustainable fisheries management strategies for the artisanal cephalopod jig fishery is critical, particularly as the global exploitation of cephalopods continues to increase with declining finfish populations. Failure to implement management strategies may remove this critical economic safety net for vulnerable coastal communities which have little alternative livelihood opportunities. Ongoing ecological research, a co-management approach and an increased consideration of local ecological knowledge will assist in designing appropriate management plans for the southern Angolan cephalopod jig fishery. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Vázquez Morán, Chénelle Lesley
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422529 , vital:71955 , DOI 10.21504/10962/422529
- Description: The global decline in marine finfish stocks has been met with a concomitant expansion of fisheries for cephalopods. Despite the increase in the exploitation and commercialization of cephalopods, there is a dearth of scientific information for over 90% of the extant species and this is even more marked in the developing world. Angolan capture fisheries production noted a tenfold increase in cephalopod landings between 1994 and 2003. One of the important fisheries is a cephalopod directed jig fishery that targets the squid Loligo reynaudii and the cuttlefish Sepia vermiculata in southern Angola, however, there is a complete lack of socio-ecological information available for this fishery. Hence the aim of this thesis was to provide basic biological and demographic information on L. reynaudii and S. vermiculata distributed off the coast of southern Angola, assess the importance and dependence of local artisanal fishers on these two species and examine the current management strategies and policies in the region This study found that the artisanal cephalopod jig fishery is critical for the livelihoods of the coastal communities of southern Angola, particularly due to the limited alternative income generating opportunities available. The cephalopod jig fishery is highly labour intensive, with fishers spending a considerable amount of time per day, drifting over known fishing grounds. Catch composition of the artisanal jig fishery indicated that squid is the dominant species within the fishery, in terms of numerical abundance and weight. The productivity and progression of the fishery is hampered by a number of ecological, socio-economic and governance constraints, as highlighted by socio-economic surveys conducted with local squid fishers. Such constraints include, but are not limited to declining catches, increased negative interactions with seals, increased inter-sector competition, lack of infrastructure, poor quality fishing equipment as well as a lack of communication and support from government officials. To examine aspects of the biology and demography of L. reynaudii, whole specimens were collected monthly, from the two primary fishing areas in southern Angola; Namibe and Tombua, during two main sampling periods, June 2008 – May 2009 (Period 1) and June 2014 – May 2015 (Period 2). Male L. reynaudii were found to be significantly larger in size and weight than females, however both the average and maximum dorsal mantle length (DML) decreased between sampling periods. Length-at-50% maturity was larger for male L. reynaudii (170.47 mm DML – 1st period, 165.44 mm DML – 2nd period) than female L. reynaudii (114.71 mm DML – 1st period, 109.43 mm DML – 2nd period). Gonadosomatic indices (GSI) varied significantly during month and season for both sexes. Peak GSI coincided with a low catches in the artisanal jig fishery suggesting that the population may undergo a spawning migration away from fishing grounds, during late spring and summer. The theory of a seasonal spawning migration is further supported in this study by the low abundance of juvenile and sub-adult L, reynaudii collected during the study, along with the inability to detect egg beds in known fishing grounds. Stomach content analysis indicated that teleosts were the most important dietary item (66.3% F of the stomach contents). Trachurus capensis and Engraulis encrasicolus are both highly abundant small pelagic fishes in the cold nutrient rich waters of the Benguela Current and dominated the diet of sampled squid during autumn and winter months. It is likely that the prevalence of large, adult squid off the coast of Angola, as observed within the current study, may be ascribed to the suitable environmental conditions and the abundance of suitable prey. The results from the current study indicate that the southern Angolan subpopulation reveals similarities to that of the West Coast subpopulation of squid in South Africa, with regards to demographics and reproductive characteristics. It is likely that the population in southern Angola is an extension of the South African subpopulation of L. reynaudii on the western extremities. To examine the basic population biology and ecology of S. vermiculata off southern Angola whole specimens were collected from the fishery between December 2014 and April 2015. Morphological results indicate clear sexual dimorphism in soft part characteristics, cuttlebone and beak morphometry. Length-at-50% maturity was smaller in male S. vermiculata (217.53 mm DML) than female S. vermiculata (231.13 mm DML), although these differences were not significant. Stomach content analysis indicated that S. vermiculata predominantly fed on teleost species which were found within 64.5% of stomachs. Teleosts were more dominant in the diet of male S. vermiculata (78.6% F) than female S. vermiculata (53.0% F), which ate a more varied diet including crustaceans (41.2% F) and cephalopods (17.7% F). Availability and abundance of cuttlefish in Namibe indicates that the species may undergo a spatio-temporal shift in distribution, with majority of the artisanal catches of S. vermiculata occurring during summer months. The results from the current study highlights the fisheries potential of L. reynaudii and S. vermiculata and the dependence of artisanal fishers in southern Angola on cephalopods, and more specifically squid. The development of sustainable fisheries management strategies for the artisanal cephalopod jig fishery is critical, particularly as the global exploitation of cephalopods continues to increase with declining finfish populations. Failure to implement management strategies may remove this critical economic safety net for vulnerable coastal communities which have little alternative livelihood opportunities. Ongoing ecological research, a co-management approach and an increased consideration of local ecological knowledge will assist in designing appropriate management plans for the southern Angolan cephalopod jig fishery. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-03-31
Evaluation of the effectiveness of small aperture network telescopes as IBR data sources
- Authors: Chindipha, Stones Dalitso
- Date: 2023-03-31
- Subjects: Computer networks Monitoring , Computer networks Security measures , Computer bootstrapping , Time-series analysis , Regression analysis , Mathematical models
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/366264 , vital:65849 , DOI https://doi.org/10.21504/10962/366264
- Description: The use of network telescopes to collect unsolicited network traffic by monitoring unallocated address space has been in existence for over two decades. Past research has shown that there is a lot of activity happening in this unallocated space that needs monitoring as it carries threat intelligence data that has proven to be very useful in the security field. Prior to the emergence of the Internet of Things (IoT), commercialisation of IP addresses and widespread of mobile devices, there was a large pool of IPv4 addresses and thus reserving IPv4 addresses to be used for monitoring unsolicited activities going in the unallocated space was not a problem. Now, preservation of such IPv4 addresses just for monitoring is increasingly difficult as there is not enough free addresses in the IPv4 address space to be used for just monitoring. This is the case because such monitoring is seen as a ’non-productive’ use of the IP addresses. This research addresses the problem brought forth by this IPv4 address space exhaustion in relation to Internet Background Radiation (IBR) monitoring. In order to address the research questions, this research developed four mathematical models: Absolute Mean Accuracy Percentage Score (AMAPS), Symmetric Absolute Mean Accuracy Percentage Score (SAMAPS), Standardised Mean Absolute Error (SMAE), and Standardised Mean Absolute Scaled Error (SMASE). These models are used to evaluate the research objectives and quantify the variations that exist between different samples. The sample sizes represent different lens sizes of the telescopes. The study has brought to light a time series plot that shows the expected proportion of unique source IP addresses collected over time. The study also imputed data using the smaller /24 IPv4 net-block subnets to regenerate the missing data points using bootstrapping to create confidence intervals (CI). The findings from the simulated data supports the findings computed from the models. The CI offers a boost to decision making. Through a series of experiments with monthly and quarterly datasets, the study proposed a 95% - 99% confidence level to be used. It was known that large network telescopes collect more threat intelligence data than small-sized network telescopes, however, no study, to the best of our knowledge, has ever quantified such a knowledge gap. With the findings from the study, small-sized network telescope users can now use their network telescopes with full knowledge of gap that exists in the data collected between different network telescopes. , Thesis (PhD) -- Faculty of Science, Computer Science, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Chindipha, Stones Dalitso
- Date: 2023-03-31
- Subjects: Computer networks Monitoring , Computer networks Security measures , Computer bootstrapping , Time-series analysis , Regression analysis , Mathematical models
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/366264 , vital:65849 , DOI https://doi.org/10.21504/10962/366264
- Description: The use of network telescopes to collect unsolicited network traffic by monitoring unallocated address space has been in existence for over two decades. Past research has shown that there is a lot of activity happening in this unallocated space that needs monitoring as it carries threat intelligence data that has proven to be very useful in the security field. Prior to the emergence of the Internet of Things (IoT), commercialisation of IP addresses and widespread of mobile devices, there was a large pool of IPv4 addresses and thus reserving IPv4 addresses to be used for monitoring unsolicited activities going in the unallocated space was not a problem. Now, preservation of such IPv4 addresses just for monitoring is increasingly difficult as there is not enough free addresses in the IPv4 address space to be used for just monitoring. This is the case because such monitoring is seen as a ’non-productive’ use of the IP addresses. This research addresses the problem brought forth by this IPv4 address space exhaustion in relation to Internet Background Radiation (IBR) monitoring. In order to address the research questions, this research developed four mathematical models: Absolute Mean Accuracy Percentage Score (AMAPS), Symmetric Absolute Mean Accuracy Percentage Score (SAMAPS), Standardised Mean Absolute Error (SMAE), and Standardised Mean Absolute Scaled Error (SMASE). These models are used to evaluate the research objectives and quantify the variations that exist between different samples. The sample sizes represent different lens sizes of the telescopes. The study has brought to light a time series plot that shows the expected proportion of unique source IP addresses collected over time. The study also imputed data using the smaller /24 IPv4 net-block subnets to regenerate the missing data points using bootstrapping to create confidence intervals (CI). The findings from the simulated data supports the findings computed from the models. The CI offers a boost to decision making. Through a series of experiments with monthly and quarterly datasets, the study proposed a 95% - 99% confidence level to be used. It was known that large network telescopes collect more threat intelligence data than small-sized network telescopes, however, no study, to the best of our knowledge, has ever quantified such a knowledge gap. With the findings from the study, small-sized network telescope users can now use their network telescopes with full knowledge of gap that exists in the data collected between different network telescopes. , Thesis (PhD) -- Faculty of Science, Computer Science, 2023
- Full Text:
- Date Issued: 2023-03-31
Innovation in ecological restoration techniques: Enhancing Portulacaria afra survivorship in degraded arid thicket
- Authors: Norman, Yondela Masande
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419276 , vital:71630
- Description: The Albany Thicket Biome has undergone extensive degradation over the past century, particularly from overstocking of livestock in the arid types of thicket. The degradation of the biome, coupled with little to no natural recovery, prompted the South African Government to implement the Subtropical Thicket Restoration Programme (STRP) in the early 2000s to rehabilitate degraded thicket using unrooted Portulacaria afra truncheons. The STRP also sought to create job opportunities, bring about social upliftment, promote biodiversity conservation and incentivise farmers and landowners in the region to promote carbon trading and farming of P. afra using carbon credits. However, the survivorship of P. afra planted using the STRP planting protocol has been less than ⁓30% because they are planted in degraded areas, where the truncheons are subjected to harsh biophysical conditions such as hard, capped soil, high soil temperatures, drought and herbivory. The aim of this study, therefore, was to improve the survivorship of P. afra planted in degraded thicket to at least 30%, using modified planting methods. In this study, four treatments were applied in 210 pondings (or micro-dams), each with P. afra planted in them (the first three treatments used rooted cuttings). The first treatment involved watering regimes where pondings were watered at varying frequencies. The second treatment involved planting companion species alongside P. afra while the third treatment involved planting P. afra underneath a nurse canopy. In the fourth treatment, unrooted P. afra truncheons were planted inside pondings. The mean survivorship of the P. afra cuttings was assessed 18 months after planting. The watering regime treatments, including the control, all yielded a survivorship of over 75%, with the significantly highest levels of survivorship being displayed in the weekly watering treatment (90.9 ± 6.8%) (p < 0.01). The companion plant treatment also produced a high mean survivorship of P. afra (94.9 ± 3.6%), significantly higher than that of the nurse plants (87.5 ± 6.3%) (p < 0.01). Among the unrooted truncheons it was found that untreated truncheons had the highest survivorship (76.2 ± 17.6%), with the lowest mean being found in truncheons that were both pruned and scarified (70.8 ± 20.8%), suggesting that this treatment, out of all of them, is the least successful under the prevailing environmental conditions in the study area. However, there was no significant differences among the unrooted truncheon treatments and their respective survivorship values to further substantiate this assertion (p = 0.26). Findings in this study also suggest that planting P. afra cuttings under a nurse plant was ideal for P. afra survivorship due to the nurse plant’s ability to ameliorate the microclimate under which the cuttings can establish and grow. Despite the soil under the nurse canopy having a significantly lower mean soil water potential (-160.9 ± 200.5 kPa), compared to the open areas (-73.4 ± 55.7 kPa) (p = 0.04), the pondings under the nurse canopy still had a lower mean soil temperature (31.4 ± 5.25°C) than the treatments in the open areas (38.5 ± 2.7°C), during the harsh midday sun. These favourable characteristics are reflected in the P. afra cuttings under a nurse canopy having a higher chlorophyll fluorescence (0.76 ± 0.06). compared to those planted in open areas (0.73 ± 0.13), suggesting that the P. afra cuttings in the former treatment had a higher photosynthetic efficiency compared to those in the latter, despite there being no statistically significant difference in chlorophyll fluorescence between the treatments (p = 0.14). Although these findings suggest that applying these modifications to planting P. afra, having achieved its objective of increasing survivorship to well over 50%, is likely to produce favourable results not only in overall survivorship, but also in fast-tracking arid thicket rehabilitation and restoration, further research on these rehabilitation techniques and their effectiveness is required. Furthermore, the downside to these treatments is that they are costly and time consuming, which puts the feasibility of large-scale programmes using these applications into question. Further investigation is required to determine ways in which the cost-effectiveness of these applications can be enhanced. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Norman, Yondela Masande
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419276 , vital:71630
- Description: The Albany Thicket Biome has undergone extensive degradation over the past century, particularly from overstocking of livestock in the arid types of thicket. The degradation of the biome, coupled with little to no natural recovery, prompted the South African Government to implement the Subtropical Thicket Restoration Programme (STRP) in the early 2000s to rehabilitate degraded thicket using unrooted Portulacaria afra truncheons. The STRP also sought to create job opportunities, bring about social upliftment, promote biodiversity conservation and incentivise farmers and landowners in the region to promote carbon trading and farming of P. afra using carbon credits. However, the survivorship of P. afra planted using the STRP planting protocol has been less than ⁓30% because they are planted in degraded areas, where the truncheons are subjected to harsh biophysical conditions such as hard, capped soil, high soil temperatures, drought and herbivory. The aim of this study, therefore, was to improve the survivorship of P. afra planted in degraded thicket to at least 30%, using modified planting methods. In this study, four treatments were applied in 210 pondings (or micro-dams), each with P. afra planted in them (the first three treatments used rooted cuttings). The first treatment involved watering regimes where pondings were watered at varying frequencies. The second treatment involved planting companion species alongside P. afra while the third treatment involved planting P. afra underneath a nurse canopy. In the fourth treatment, unrooted P. afra truncheons were planted inside pondings. The mean survivorship of the P. afra cuttings was assessed 18 months after planting. The watering regime treatments, including the control, all yielded a survivorship of over 75%, with the significantly highest levels of survivorship being displayed in the weekly watering treatment (90.9 ± 6.8%) (p < 0.01). The companion plant treatment also produced a high mean survivorship of P. afra (94.9 ± 3.6%), significantly higher than that of the nurse plants (87.5 ± 6.3%) (p < 0.01). Among the unrooted truncheons it was found that untreated truncheons had the highest survivorship (76.2 ± 17.6%), with the lowest mean being found in truncheons that were both pruned and scarified (70.8 ± 20.8%), suggesting that this treatment, out of all of them, is the least successful under the prevailing environmental conditions in the study area. However, there was no significant differences among the unrooted truncheon treatments and their respective survivorship values to further substantiate this assertion (p = 0.26). Findings in this study also suggest that planting P. afra cuttings under a nurse plant was ideal for P. afra survivorship due to the nurse plant’s ability to ameliorate the microclimate under which the cuttings can establish and grow. Despite the soil under the nurse canopy having a significantly lower mean soil water potential (-160.9 ± 200.5 kPa), compared to the open areas (-73.4 ± 55.7 kPa) (p = 0.04), the pondings under the nurse canopy still had a lower mean soil temperature (31.4 ± 5.25°C) than the treatments in the open areas (38.5 ± 2.7°C), during the harsh midday sun. These favourable characteristics are reflected in the P. afra cuttings under a nurse canopy having a higher chlorophyll fluorescence (0.76 ± 0.06). compared to those planted in open areas (0.73 ± 0.13), suggesting that the P. afra cuttings in the former treatment had a higher photosynthetic efficiency compared to those in the latter, despite there being no statistically significant difference in chlorophyll fluorescence between the treatments (p = 0.14). Although these findings suggest that applying these modifications to planting P. afra, having achieved its objective of increasing survivorship to well over 50%, is likely to produce favourable results not only in overall survivorship, but also in fast-tracking arid thicket rehabilitation and restoration, further research on these rehabilitation techniques and their effectiveness is required. Furthermore, the downside to these treatments is that they are costly and time consuming, which puts the feasibility of large-scale programmes using these applications into question. Further investigation is required to determine ways in which the cost-effectiveness of these applications can be enhanced. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2023
- Full Text:
- Date Issued: 2023-03-31
Instrument building as a tool for the revitalisation and revaluing of traditional music transmission: An investigation in Tshandama and Mbahe in Venda, South Africa
- Authors: Makhanza, Joseph
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419525 , vital:71651
- Description: This study stems from my experiences as a child who grew up playing herd boys’ musical instruments from Venda, such as the tshipotoliyo (ocarina), and tshitiringo (flute). Importantly it also builds on my time working at the International Library of African Music (ILAM,) where the aforementioned instruments, as well as the dende (musical bow) and tshizambi (Vhavenda and Vatsonga mouth bow), are displayed in transparent glass cubicles with a note, “Do not touch, they are fragile”. This phrase is painfully apt because, as a musician, I have observed a decline in the availability and performance of these musical instruments. The truth is that, other than at ILAM, these instruments are hardly in circulation, let alone being performed. This fact ignited my interest in relearning some of the musical instruments I used to play and make while herding cows in Giyani. In the context of trends such as modernisation, rural–urban migration, and globalisation, I document my experiences as a musical-instrument maker, teacher, and performer in revitalising dende, tshipotoliyo, tshitiringo, and tshizambi through classroom practice, using Rhodes music students, instrument-making workshops, performances, and community collaborations as inspiration. I propose the development of crafting skills as a medium for revitalising and sustaining these musical instruments which serve as important identity markers of the Vhavenda people. , Thesis (MMus) -- Faculty of Humanities, Music and Musicology, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Makhanza, Joseph
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419525 , vital:71651
- Description: This study stems from my experiences as a child who grew up playing herd boys’ musical instruments from Venda, such as the tshipotoliyo (ocarina), and tshitiringo (flute). Importantly it also builds on my time working at the International Library of African Music (ILAM,) where the aforementioned instruments, as well as the dende (musical bow) and tshizambi (Vhavenda and Vatsonga mouth bow), are displayed in transparent glass cubicles with a note, “Do not touch, they are fragile”. This phrase is painfully apt because, as a musician, I have observed a decline in the availability and performance of these musical instruments. The truth is that, other than at ILAM, these instruments are hardly in circulation, let alone being performed. This fact ignited my interest in relearning some of the musical instruments I used to play and make while herding cows in Giyani. In the context of trends such as modernisation, rural–urban migration, and globalisation, I document my experiences as a musical-instrument maker, teacher, and performer in revitalising dende, tshipotoliyo, tshitiringo, and tshizambi through classroom practice, using Rhodes music students, instrument-making workshops, performances, and community collaborations as inspiration. I propose the development of crafting skills as a medium for revitalising and sustaining these musical instruments which serve as important identity markers of the Vhavenda people. , Thesis (MMus) -- Faculty of Humanities, Music and Musicology, 2023
- Full Text:
- Date Issued: 2023-03-31
Internal barriers facing small business owners adopting financial management practices in Makana Municipality, Eastern Cape
- Authors: Tendayi, Elizabeth
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419484 , vital:71648
- Description: Although small businesses are important in South Africa, they have a high failure rate. About 63 percent of small businesses in South Africa fail in the first 18 months of their inception (Van Staden, 2022; Zhou, 2021; Bruwer, 2020: 148). One of the reasons for the failure of small businesses is the improper and ineffective adoption of proper financial management practices (Zada, Yukun and Zada, 2021: 1074). However, the success of small businesses is highly dependent on the adoption of proper financial management practices (Kapitsinis, 2019; Jindrichovska, 2013; Abuzayed, 2012; Kaya and Alpkan, 2012; Banos-Caballero, Garcia-Teruel and Martinez-Solano, 2010). In the Eastern Cape, most small businesses do not adopt proper financial management practices (Raj, 2012; Van Eeden, Viviers and Venter, 2003:1). Therefore, the study aimed to analyse internal barriers facing small business owners adopting proper financial management practices in Makana Municipality in the Eastern Cape. Eastern Cape. Proper financial management practices are evident where there is transparency, efficiency and accuracy in the achievement of the financial objectives of a business (Cheluget and Morogo, 2017: 215). Financial management practices include cash management practices, accounts receivables management practices, accounts payables management practices, inventory management practices, working capital management practices, investment management or capital budgeting practices, financing or capital structure practices, accounting information systems, financial reporting and analysis practices. The study adopted a qualitative research design and a case study methodology. A non-probability judgment sampling method was used to select a sample of twelve small business owners in Makanda, Makana Municipality. Makanda was a relevant study area because it has a high unemployment rate and poverty, and small businesses may be used as one of the driving forces in the reduction of poverty and unemployment in Makana Municipality (Eastern Cape Socio Economic Consultative Council, 2017: 1; Zemenu and Mohammed, 2014: 2; Alebiosu, 2005: 5). Primary data was collected through semi-structured interviews. Content analysis was used to describe and interpret qualitative data using coding and themes. The findings of the study showed that most small business owners or managers in Makana Municipality adopted cash management practices, working capital management practices, inventory management practices, capital structure (equity capital) practices and financial reporting and analysis. However, it was also found that small business owners or managers in Makana Municipality did not adopt accounts receivables management practices, accounts payables management practices, capital structure (debt capital) practices, accounting information systems and capital budgeting (investment) management practices. These barriers included difficulty in debt collection, cost of debt collection, nature of product or industry, challenges with suppliers or creditors, Covid-19, debt avoidance, improvement of cash flow, negative attitude towards computer systems, waste of resources and difficulty use of computer systems. It is recommended that small businesses may overcome these barriers by implementing proper debt collection procedures, honouring credit payments terms with suppliers or creditors, consulting external accountants on how to balance the use of both debt and equity capital, hiring qualified personnel to acquire training and bring awareness to the use of computer systems. In addition, the government should provide financial education programmes that specifically deal with long-term investments, and small businesses are encouraged to apply for Covid-19 rescue packages or grants through role plates such as Debt Relief Finance Scheme and the Small Enterprise Finance Agency (SEFA). It was concluded that each small business adopts financial management practices differently due to the nature of the business or industry. Also, the adoption of financial management practices is dependent on the exposure of the different barriers within each business. Hence, this study confirms that the contingency theory may be used to explain that the adoption of financial management practices is dependent upon the nature of the business or industry and the different barriers that small businesses face. Theoretically, this study contributed to the existing literature by analysing the barriers faced by small business owners adopting financial management practices in the Eastern Cape. Practically, this study highlighted the internal barriers that small business owners need to overcome to the adoption of financial management practices. , Thesis (MCom) -- Faculty of Commerce, Management, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Tendayi, Elizabeth
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419484 , vital:71648
- Description: Although small businesses are important in South Africa, they have a high failure rate. About 63 percent of small businesses in South Africa fail in the first 18 months of their inception (Van Staden, 2022; Zhou, 2021; Bruwer, 2020: 148). One of the reasons for the failure of small businesses is the improper and ineffective adoption of proper financial management practices (Zada, Yukun and Zada, 2021: 1074). However, the success of small businesses is highly dependent on the adoption of proper financial management practices (Kapitsinis, 2019; Jindrichovska, 2013; Abuzayed, 2012; Kaya and Alpkan, 2012; Banos-Caballero, Garcia-Teruel and Martinez-Solano, 2010). In the Eastern Cape, most small businesses do not adopt proper financial management practices (Raj, 2012; Van Eeden, Viviers and Venter, 2003:1). Therefore, the study aimed to analyse internal barriers facing small business owners adopting proper financial management practices in Makana Municipality in the Eastern Cape. Eastern Cape. Proper financial management practices are evident where there is transparency, efficiency and accuracy in the achievement of the financial objectives of a business (Cheluget and Morogo, 2017: 215). Financial management practices include cash management practices, accounts receivables management practices, accounts payables management practices, inventory management practices, working capital management practices, investment management or capital budgeting practices, financing or capital structure practices, accounting information systems, financial reporting and analysis practices. The study adopted a qualitative research design and a case study methodology. A non-probability judgment sampling method was used to select a sample of twelve small business owners in Makanda, Makana Municipality. Makanda was a relevant study area because it has a high unemployment rate and poverty, and small businesses may be used as one of the driving forces in the reduction of poverty and unemployment in Makana Municipality (Eastern Cape Socio Economic Consultative Council, 2017: 1; Zemenu and Mohammed, 2014: 2; Alebiosu, 2005: 5). Primary data was collected through semi-structured interviews. Content analysis was used to describe and interpret qualitative data using coding and themes. The findings of the study showed that most small business owners or managers in Makana Municipality adopted cash management practices, working capital management practices, inventory management practices, capital structure (equity capital) practices and financial reporting and analysis. However, it was also found that small business owners or managers in Makana Municipality did not adopt accounts receivables management practices, accounts payables management practices, capital structure (debt capital) practices, accounting information systems and capital budgeting (investment) management practices. These barriers included difficulty in debt collection, cost of debt collection, nature of product or industry, challenges with suppliers or creditors, Covid-19, debt avoidance, improvement of cash flow, negative attitude towards computer systems, waste of resources and difficulty use of computer systems. It is recommended that small businesses may overcome these barriers by implementing proper debt collection procedures, honouring credit payments terms with suppliers or creditors, consulting external accountants on how to balance the use of both debt and equity capital, hiring qualified personnel to acquire training and bring awareness to the use of computer systems. In addition, the government should provide financial education programmes that specifically deal with long-term investments, and small businesses are encouraged to apply for Covid-19 rescue packages or grants through role plates such as Debt Relief Finance Scheme and the Small Enterprise Finance Agency (SEFA). It was concluded that each small business adopts financial management practices differently due to the nature of the business or industry. Also, the adoption of financial management practices is dependent on the exposure of the different barriers within each business. Hence, this study confirms that the contingency theory may be used to explain that the adoption of financial management practices is dependent upon the nature of the business or industry and the different barriers that small businesses face. Theoretically, this study contributed to the existing literature by analysing the barriers faced by small business owners adopting financial management practices in the Eastern Cape. Practically, this study highlighted the internal barriers that small business owners need to overcome to the adoption of financial management practices. , Thesis (MCom) -- Faculty of Commerce, Management, 2023
- Full Text:
- Date Issued: 2023-03-31
Investigating the use of nudging to dissuade online banking fraud
- Mutyavariri, Takudzwa Stanley
- Authors: Mutyavariri, Takudzwa Stanley
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419462 , vital:71646
- Description: Online banking is a service offered by most modern banks to provide their clients with a convenient means to access their bank accounts remotely. However, such convenience comes at a cost and has the potential to expose clients to online banking fraud. To mitigate such forms of fraud, banks make extensive use of traditional cybersecurity measures such as firewalls, intrusion detection systems, as well as personal identification numbers (PINs) and passwords. However, despite the use of such traditional cybersecurity measures, online banking fraud still occurs. In particular, traditional cybersecurity measures have difficulties detecting the unauthorised use of a customer’s online banking credentials. For this reason, this study’s main objective was to investigate the effectiveness of nudges when used to dissuade the unauthorised use of clients’ online banking credentials. The study also had two secondary objectives: firstly, to identify where the deployment of nudges would be most effective; and secondly, to identify the rationalisations an individual may use to justify committing online banking fraud. Although previous research has sought to understand the use of nudges in various online contexts, none have done so within the context of online banking. Using a recontextualised version of the COM-B (capability, opportunity, motivation – behaviour) model of behaviour change, nudges were deployed in three versions of a fictitious online banking website. Following this, 15 semi-structured interviews were conducted with online banking users from the United States of America to understand how a third party may behave and rationalise their choices when they have unauthorised access to a customer’s online banking credentials. The transcripts of these interviews were analysed using thematic analysis. The findings revealed that the most dissuasive nudges focused on encouraging individuals to empathise with the account holder. Nudges that increased the perception of an online banking website’s security were also particularly dissuasive. The findings also indicated that the most effective place to deploy these nudges was after a user had logged in. Several rationalisations that enabled individuals to commit online baking fraud were found. The three most common were crime of opportunity, down on their luck, and sunk cost fallacy and curiosity. Together, the findings provide evidence to suggest that, if used effectively, nudges could prove useful as a means of dissuading online banking fraud, and even more so when combined with traditional cybersecurity measures. , Thesis (MCom) -- Faculty of Commerce, Information Systems, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Mutyavariri, Takudzwa Stanley
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419462 , vital:71646
- Description: Online banking is a service offered by most modern banks to provide their clients with a convenient means to access their bank accounts remotely. However, such convenience comes at a cost and has the potential to expose clients to online banking fraud. To mitigate such forms of fraud, banks make extensive use of traditional cybersecurity measures such as firewalls, intrusion detection systems, as well as personal identification numbers (PINs) and passwords. However, despite the use of such traditional cybersecurity measures, online banking fraud still occurs. In particular, traditional cybersecurity measures have difficulties detecting the unauthorised use of a customer’s online banking credentials. For this reason, this study’s main objective was to investigate the effectiveness of nudges when used to dissuade the unauthorised use of clients’ online banking credentials. The study also had two secondary objectives: firstly, to identify where the deployment of nudges would be most effective; and secondly, to identify the rationalisations an individual may use to justify committing online banking fraud. Although previous research has sought to understand the use of nudges in various online contexts, none have done so within the context of online banking. Using a recontextualised version of the COM-B (capability, opportunity, motivation – behaviour) model of behaviour change, nudges were deployed in three versions of a fictitious online banking website. Following this, 15 semi-structured interviews were conducted with online banking users from the United States of America to understand how a third party may behave and rationalise their choices when they have unauthorised access to a customer’s online banking credentials. The transcripts of these interviews were analysed using thematic analysis. The findings revealed that the most dissuasive nudges focused on encouraging individuals to empathise with the account holder. Nudges that increased the perception of an online banking website’s security were also particularly dissuasive. The findings also indicated that the most effective place to deploy these nudges was after a user had logged in. Several rationalisations that enabled individuals to commit online baking fraud were found. The three most common were crime of opportunity, down on their luck, and sunk cost fallacy and curiosity. Together, the findings provide evidence to suggest that, if used effectively, nudges could prove useful as a means of dissuading online banking fraud, and even more so when combined with traditional cybersecurity measures. , Thesis (MCom) -- Faculty of Commerce, Information Systems, 2023
- Full Text:
- Date Issued: 2023-03-31
Phytoplankton communities provide insight into ecosystem functioning of the Agulhas Current system
- Authors: Gibb, Ross-Lynne Alida
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422646 , vital:71965
- Description: Access restricted. Embargoed until 2025. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Gibb, Ross-Lynne Alida
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422646 , vital:71965
- Description: Access restricted. Embargoed until 2025. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2023
- Full Text:
- Date Issued: 2023-03-31
Rapid Synthesis of Thiol-Co-Capped CdTe/CdSe/ZnSe Multi-Core-Shell QDs and Their Encapsulation in Liposomes and Chitosan Nanoparticles; Comparative Bio-compatibility Studies Using Hela and Vero Cells
- Authors: Daramola, Olamide Abiodun
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422617 , vital:71962 , DOI 10.21504/10962/422617
- Description: The common method that has been used to reduce the toxicity posed to living cells by CdTe Quantum Dots (QDs) is through the synthesis of CdTe multi-core-shells nanoparticles. In this process, the surface of CdTe QDs is usually coated by less toxic ZnS or ZnSe shells. This heterostructure compound does not only reduce the toxicity of CdTe QDs but can also be used in applications such as deep tissue imaging. The heterostructures can be in numerous forms such as CdTe/CdSe/ZnSe or CdTe/CdSe/ZnS or CdTe/CdS/ZnS multi-core-shell QDs. However, the drawbacks attributed to the fabrication of these compounds is long synthesis times (6- 24 h) in achieving the highest wavelength emission maxima. Others are the use of toxic reagents and poor reproducibility of synthesized materials. An additional problem is that the ZnSe or ZnS coating is insufficient to completely protect the highly toxic Cd metal from escaping into immediate solution. This limits their use in biochemistry and with living systems. Liposomes and biopolymers such as chitosan are known to be environmentally friendly compounds that have been used in various studies as delivery systems for QDs and model drugs for drug delivery applications. They are generally non-toxic and highly bio-compatible. In this study, the rapid synthesis of thiol-co-capped CdTe/CdSe/ZnSe multi-core-shell QDs with a maximum reaction time of 35 mins, gave reliable QDs with emission maxima at 625 nm. The multi-core-shell QDs were encapsulated in two different bio-compatible environments, namely liposome and chitosan nanoparticles (CNP) at 14 different formulations (F) for liposome and 12 different formulations for CNP. Cytotoxicity and florescence imaging studies using HeLa and Vero cells, were used to investigate the improved bio-compatibility. Various characterization techniques were used to elucidate the optical properties, morphology and physico-chemical properties of the QDs and nanocomposites. Two of the best formulations, QD-liposome vesicles (LVs)-F12 and QD-CNP-F9 (with chitosan), demonstrated high loading efficiencies of 42 ± 6 % and 59 ± 5 %, respectively. While the plain CdTe QDs showed high toxicity, some of the encapsulated materials, QD-LVs-F1 and F12, depicted no-toxicity against the cells (IC50 > 0.5 mg/ml). The QDs also retained most of their fluorescence and properties and could easily be tracked in cells and visualized around the nucleus, indicating the successful internalization of the QDs in the cytosol. These results shows that encapsulation of CdTe multi-core-shell QDs in liposomes produce better bio-compatibility compared to multi-core-shell QDs and better than CNP coating. These particles therefore show good promise in cell-labelling, drug delivery studies. Their core-shell nanoparticles have also shown good behavior in enhancing the memory of a device which is based on some recent collaborated works. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Daramola, Olamide Abiodun
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422617 , vital:71962 , DOI 10.21504/10962/422617
- Description: The common method that has been used to reduce the toxicity posed to living cells by CdTe Quantum Dots (QDs) is through the synthesis of CdTe multi-core-shells nanoparticles. In this process, the surface of CdTe QDs is usually coated by less toxic ZnS or ZnSe shells. This heterostructure compound does not only reduce the toxicity of CdTe QDs but can also be used in applications such as deep tissue imaging. The heterostructures can be in numerous forms such as CdTe/CdSe/ZnSe or CdTe/CdSe/ZnS or CdTe/CdS/ZnS multi-core-shell QDs. However, the drawbacks attributed to the fabrication of these compounds is long synthesis times (6- 24 h) in achieving the highest wavelength emission maxima. Others are the use of toxic reagents and poor reproducibility of synthesized materials. An additional problem is that the ZnSe or ZnS coating is insufficient to completely protect the highly toxic Cd metal from escaping into immediate solution. This limits their use in biochemistry and with living systems. Liposomes and biopolymers such as chitosan are known to be environmentally friendly compounds that have been used in various studies as delivery systems for QDs and model drugs for drug delivery applications. They are generally non-toxic and highly bio-compatible. In this study, the rapid synthesis of thiol-co-capped CdTe/CdSe/ZnSe multi-core-shell QDs with a maximum reaction time of 35 mins, gave reliable QDs with emission maxima at 625 nm. The multi-core-shell QDs were encapsulated in two different bio-compatible environments, namely liposome and chitosan nanoparticles (CNP) at 14 different formulations (F) for liposome and 12 different formulations for CNP. Cytotoxicity and florescence imaging studies using HeLa and Vero cells, were used to investigate the improved bio-compatibility. Various characterization techniques were used to elucidate the optical properties, morphology and physico-chemical properties of the QDs and nanocomposites. Two of the best formulations, QD-liposome vesicles (LVs)-F12 and QD-CNP-F9 (with chitosan), demonstrated high loading efficiencies of 42 ± 6 % and 59 ± 5 %, respectively. While the plain CdTe QDs showed high toxicity, some of the encapsulated materials, QD-LVs-F1 and F12, depicted no-toxicity against the cells (IC50 > 0.5 mg/ml). The QDs also retained most of their fluorescence and properties and could easily be tracked in cells and visualized around the nucleus, indicating the successful internalization of the QDs in the cytosol. These results shows that encapsulation of CdTe multi-core-shell QDs in liposomes produce better bio-compatibility compared to multi-core-shell QDs and better than CNP coating. These particles therefore show good promise in cell-labelling, drug delivery studies. Their core-shell nanoparticles have also shown good behavior in enhancing the memory of a device which is based on some recent collaborated works. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-03-31
South African supratidal microbialites: prokaryote communities, metabolic capabilities, and biogeochemical processes
- Authors: Isemonger, Eric William
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422641 , vital:71964
- Description: Access restricted. Embargoed until 2025. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2023
- Full Text:
- Date Issued: 2023-03-31
- Authors: Isemonger, Eric William
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/422641 , vital:71964
- Description: Access restricted. Embargoed until 2025. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2023
- Full Text:
- Date Issued: 2023-03-31