Top-down control by grapsoid crabs in South African estuarine salt marshes
- Authors: Smith, Leigh-Ann
- Date: 2023-04
- Subjects: Salt marsh ecology – South Africa , Crabs --South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/61223 , vital:69807
- Description: Salt marshes are one of the most productive ecosystems globally. These ‘blue carbon’ habitats are in many respects resilient to climate change effects, able to track sea level rise and act as carbon sinks. Since salt marshes are economically and ecologically essential habitats (for example providing foraging grounds for invertebrates, fish, birds and humans), understanding the processes that control their structure is crucial to best maintain ecosystem services provided by these habitats. For decades the importance of top-down forces, such as grazing, has not been recognised as being important in controlling salt marsh plant productivity. Rather, bottom-up forces, such as the availability of oxygen, was thought to be the main constraint to primary production. Therefore, a better understanding of salt marsh ecosystem dynamics and whether grazer control exists is needed. Although grazer top-down control has been demonstrated in salt marshes in locations such as the United States, this has not been investigated in South Africa. This is a crucial knowledge gap locally considering the importance of salt marsh ecosystems. The aim of this study was therefore to determine what role consumers play in structuring South Africa’s estuarine salt marsh vegetation, thereby also contextualising this process internationally. In order to achieve this, the abundance of grapsoid crabs was estimated and related to key salt marsh features, such as Spartina maritima stem height and stem density, which was quantified from observational surveys. Sampling took place at the beginning and end of the early-spring and late-summer growth period (September 2021 and April 2022) in the Knysna, Kromme and Swartkops estuaries. If a correlation was observed between crab density and salt marsh features, it was important to determine whether they consume the salt marsh vegetation or if the effect was due to their burrowing activities. Hence, the diet of grapsoid crabs was investigated using stable isotope and gut content analysis. To examine the importance of crab grazing in controlling the growth of salt marsh vegetation, crab abundance was manipulated in situ by means of exclusion cages. This experiment ran for five months in the Kromme Estuary, from November 2021 to March 2022 over the salt marsh growing season. An ex situ feeding experiment was also conducted on 30 crab specimens collected from the Kromme Estuary, during May 2022. These crabs were starved for 48 hours and thereafter fed different components of Spartina (growing and dead blades, and roots and rhizomes). The food consumed was quantified as the change in plant length and dry weight after 48 hours, which gave a maximum grazing rate for the different food sources. It was found that crabs are having a minimal impact on the salt marsh vegetation structure. Spartina maritima does form an important component of the diet of grapsoid crabs, however, this is not their only source of food, and possibly not their preferred source of food. They are however contributing to sediment properties through their burrowing activities. The iii ex situ feeding experiment showed that grapsoid crabs can consume all vegetative components of Spartina, with a significantly greater amount of roots and rhizomes consumed. There was no consistent effect in terms of the exclusion of grazers, indicating that other mitigating factors could be reducing the impacts of grapsoid exclusion in situ. Together, these findings contribute knowledge that can be used to inform conservation by quantifying what the salt marsh risks losing in the absence or overabundance of crabs, as has occurred elsewhere globally. These results influence how salt marshes are managed, and highlight how not recognising the importance of consumers, such as crabs, could misalign management objectives. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2023-04
- Authors: Smith, Leigh-Ann
- Date: 2023-04
- Subjects: Salt marsh ecology – South Africa , Crabs --South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/61223 , vital:69807
- Description: Salt marshes are one of the most productive ecosystems globally. These ‘blue carbon’ habitats are in many respects resilient to climate change effects, able to track sea level rise and act as carbon sinks. Since salt marshes are economically and ecologically essential habitats (for example providing foraging grounds for invertebrates, fish, birds and humans), understanding the processes that control their structure is crucial to best maintain ecosystem services provided by these habitats. For decades the importance of top-down forces, such as grazing, has not been recognised as being important in controlling salt marsh plant productivity. Rather, bottom-up forces, such as the availability of oxygen, was thought to be the main constraint to primary production. Therefore, a better understanding of salt marsh ecosystem dynamics and whether grazer control exists is needed. Although grazer top-down control has been demonstrated in salt marshes in locations such as the United States, this has not been investigated in South Africa. This is a crucial knowledge gap locally considering the importance of salt marsh ecosystems. The aim of this study was therefore to determine what role consumers play in structuring South Africa’s estuarine salt marsh vegetation, thereby also contextualising this process internationally. In order to achieve this, the abundance of grapsoid crabs was estimated and related to key salt marsh features, such as Spartina maritima stem height and stem density, which was quantified from observational surveys. Sampling took place at the beginning and end of the early-spring and late-summer growth period (September 2021 and April 2022) in the Knysna, Kromme and Swartkops estuaries. If a correlation was observed between crab density and salt marsh features, it was important to determine whether they consume the salt marsh vegetation or if the effect was due to their burrowing activities. Hence, the diet of grapsoid crabs was investigated using stable isotope and gut content analysis. To examine the importance of crab grazing in controlling the growth of salt marsh vegetation, crab abundance was manipulated in situ by means of exclusion cages. This experiment ran for five months in the Kromme Estuary, from November 2021 to March 2022 over the salt marsh growing season. An ex situ feeding experiment was also conducted on 30 crab specimens collected from the Kromme Estuary, during May 2022. These crabs were starved for 48 hours and thereafter fed different components of Spartina (growing and dead blades, and roots and rhizomes). The food consumed was quantified as the change in plant length and dry weight after 48 hours, which gave a maximum grazing rate for the different food sources. It was found that crabs are having a minimal impact on the salt marsh vegetation structure. Spartina maritima does form an important component of the diet of grapsoid crabs, however, this is not their only source of food, and possibly not their preferred source of food. They are however contributing to sediment properties through their burrowing activities. The iii ex situ feeding experiment showed that grapsoid crabs can consume all vegetative components of Spartina, with a significantly greater amount of roots and rhizomes consumed. There was no consistent effect in terms of the exclusion of grazers, indicating that other mitigating factors could be reducing the impacts of grapsoid exclusion in situ. Together, these findings contribute knowledge that can be used to inform conservation by quantifying what the salt marsh risks losing in the absence or overabundance of crabs, as has occurred elsewhere globally. These results influence how salt marshes are managed, and highlight how not recognising the importance of consumers, such as crabs, could misalign management objectives. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2023-04
Towards a Cybersecurity Skills Framework for South Africa
- Authors: Kruger, M
- Date: 2023-04
- Subjects: Computer systems--Security measures , Frameworks (Structures) -- South Africa
- Language: English
- Type: Master's theses , Thesis
- Identifier: http://hdl.handle.net/10948/61200 , vital:69793
- Description: Cybersecurity is an ever-growing area of concern both globally and in South Africa. The increasing number of cyberattacks daily has had a large effect on individuals, organisations, governments, and society at large. The growing need to combat cybercrime is accompanied by the increased need for skilled IT professionals to assist in protecting against cybercrime. Currently, there is a worldwide cybersecurity skills gap and a lack of IT professionals with the requisite cybersecurity skills. Many countries have developed their own taxonomies and common lexicons for IT and cybersecurity work, specifically for their context. This type of common lexicon is important to help assist in the development of skills. However, South Africa does not yet have its own cybersecurity skills framework to serve as a common lexicon for the South African context. Hence, the problem defined for this study is that, without a common lexicon of the cybersecurity knowledge, skills, abilities, and tasks (KSATs) required of IT professionals as they relate to specific IT job roles in South Africa, the cybersecurity skills gap cannot be sufficiently addressed. Such a lexicon could help drive the development of skills in South Africa and, in so doing assist in alleviating the cybersecurity skills gap. This study therefore presents a common lexicon by collecting job postings over a four-month period from 1 October 2020 to 31 January 2021. These job postings were analysed using a thematic content analysis. The results identified 20 common IT job roles, together with the specific KSATs relating to each job role identified. As a result, these job roles form part of a proposed cybersecurity skills framework for South Africa (CSFwSA) which could help and guide South Africa towards more targeted cybersecurity skills development. The proposed framework could also be useful in guiding tertiary educational facilities in the creation of cybersecurity curricula that represent the real-world expectations. This, in turn, could help South Africa to address the cybersecurity skills gap by better preparing IT professionals and ensuring that they are trained and skilled in cybersecurity. , Thesis (MIT) -- Faculty of Engineering, the Built Environment and Technology, School of Information Technology, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Kruger, M
- Date: 2023-04
- Subjects: Computer systems--Security measures , Frameworks (Structures) -- South Africa
- Language: English
- Type: Master's theses , Thesis
- Identifier: http://hdl.handle.net/10948/61200 , vital:69793
- Description: Cybersecurity is an ever-growing area of concern both globally and in South Africa. The increasing number of cyberattacks daily has had a large effect on individuals, organisations, governments, and society at large. The growing need to combat cybercrime is accompanied by the increased need for skilled IT professionals to assist in protecting against cybercrime. Currently, there is a worldwide cybersecurity skills gap and a lack of IT professionals with the requisite cybersecurity skills. Many countries have developed their own taxonomies and common lexicons for IT and cybersecurity work, specifically for their context. This type of common lexicon is important to help assist in the development of skills. However, South Africa does not yet have its own cybersecurity skills framework to serve as a common lexicon for the South African context. Hence, the problem defined for this study is that, without a common lexicon of the cybersecurity knowledge, skills, abilities, and tasks (KSATs) required of IT professionals as they relate to specific IT job roles in South Africa, the cybersecurity skills gap cannot be sufficiently addressed. Such a lexicon could help drive the development of skills in South Africa and, in so doing assist in alleviating the cybersecurity skills gap. This study therefore presents a common lexicon by collecting job postings over a four-month period from 1 October 2020 to 31 January 2021. These job postings were analysed using a thematic content analysis. The results identified 20 common IT job roles, together with the specific KSATs relating to each job role identified. As a result, these job roles form part of a proposed cybersecurity skills framework for South Africa (CSFwSA) which could help and guide South Africa towards more targeted cybersecurity skills development. The proposed framework could also be useful in guiding tertiary educational facilities in the creation of cybersecurity curricula that represent the real-world expectations. This, in turn, could help South Africa to address the cybersecurity skills gap by better preparing IT professionals and ensuring that they are trained and skilled in cybersecurity. , Thesis (MIT) -- Faculty of Engineering, the Built Environment and Technology, School of Information Technology, 2023
- Full Text:
- Date Issued: 2023-04
Township economy performance and contribution towards economic development in Nelson Mandela Bay: Assessment using the circular flow of money
- Authors: Matambeka, Sibahle
- Date: 2023-04
- Subjects: Circular Economy , Economic Development , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/61659 , vital:71823
- Description: The study sought to explore township economic performance and contribution towards economic development in Nelson Mandela Bay, using the circular flow of money model. The study surveyed households and businesses in one of the townships in Nelson Mandela Bay (Kwazakhele). The survey reached out to 100 households and 100 businesses, totalling 200 participants. Data were analysed using descriptive and inferential statistics. The current state of the township economy is not a desirable one. There are more leakages than injections into the township economy. More township residents (especially high-income earners) choose to shop outside the township for goods because the township does not have the goods that residents need. Key findings show that township businesses are small in nature, primarily sole propriety and operate informally in the streets. Most people who work, earn R3500 and below and spend most of their income on food and groceries. Supply for the most consumed products in the township comes mainly from outside the township, and there is no circular flow in the township economy. However, there are more people working inside the township than those who work outside the township. More essential goods are found in the township than before, so residents do not have to travel outside the township to get basic groceries and food. Other findings show that the government is not intervening enough to help the township businesses through policy implementation and financial aid. Businesses in the township do not pay taxes, and this can limit what the government can do to help them. There are other business constraints that are prohibiting the township businesses to reach the optimum level, and the top cited constraint is Crime. The study recommended that government should intervene by passing a bill like the Gauteng Township Economy Bill that aims at assisting township businesses. Households should come up with other streams of income through entrepreneurship so that they can not only depend on government social grants for income. Businesses should form bulk buying groups to increase buying power to be competitive. Lastly, businesses should seek alternative sources of power because electricity is expensive, and the load-shedding is prohibiting township businesses from running efficiently. , Thesis (MA) -- Faculty of Faculty of Business and Economic Sciences, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Matambeka, Sibahle
- Date: 2023-04
- Subjects: Circular Economy , Economic Development , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/61659 , vital:71823
- Description: The study sought to explore township economic performance and contribution towards economic development in Nelson Mandela Bay, using the circular flow of money model. The study surveyed households and businesses in one of the townships in Nelson Mandela Bay (Kwazakhele). The survey reached out to 100 households and 100 businesses, totalling 200 participants. Data were analysed using descriptive and inferential statistics. The current state of the township economy is not a desirable one. There are more leakages than injections into the township economy. More township residents (especially high-income earners) choose to shop outside the township for goods because the township does not have the goods that residents need. Key findings show that township businesses are small in nature, primarily sole propriety and operate informally in the streets. Most people who work, earn R3500 and below and spend most of their income on food and groceries. Supply for the most consumed products in the township comes mainly from outside the township, and there is no circular flow in the township economy. However, there are more people working inside the township than those who work outside the township. More essential goods are found in the township than before, so residents do not have to travel outside the township to get basic groceries and food. Other findings show that the government is not intervening enough to help the township businesses through policy implementation and financial aid. Businesses in the township do not pay taxes, and this can limit what the government can do to help them. There are other business constraints that are prohibiting the township businesses to reach the optimum level, and the top cited constraint is Crime. The study recommended that government should intervene by passing a bill like the Gauteng Township Economy Bill that aims at assisting township businesses. Households should come up with other streams of income through entrepreneurship so that they can not only depend on government social grants for income. Businesses should form bulk buying groups to increase buying power to be competitive. Lastly, businesses should seek alternative sources of power because electricity is expensive, and the load-shedding is prohibiting township businesses from running efficiently. , Thesis (MA) -- Faculty of Faculty of Business and Economic Sciences, 2023
- Full Text:
- Date Issued: 2023-04
Transfer of technological innovation for socio-economic development: the case of small and medium-sized enterprises (SMEs) in ACCRA, Ghana
- Authors: Anoku, John Kofie
- Date: 2023-04
- Subjects: Developing economies , Research & development
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/60537 , vital:65643
- Description: The importance of technological innovation transfer to a country’s socio-economic development cannot be underestimated. This is because technological innovation provides the base for today’s knowledge-based economy. As a developing economy, Ghana faces several socio-economic development challenges as those of other developing economies. Despite these socio-economic challenges, it has been shown that thriving Small and Medium Size Enterprises (SMEs) in Ghana, could help improve the socio-economic development of the Ghanaian economy. Notwithstanding the valuable contributions of SMEs to socio-economic development in Ghana, there appears to be a more significant disconnect between research outcomes from research institutions to SMEs in the areas of technological innovation transfer. It appears there is no bridge between research institutions and SMEs. Against this backdrop, the study aimed at investigating how the transfer of technological innovation from research institutions to SMEs could enable SMEs to thrive and improve the socio-economic development of the Ghanaian economy. A mixed methods research approach was used for the study. The study applied a stratified sampling technique to select 432 CEOs of SMEs from a total population of 481CEOs which represents all CEOs of SMEs in the Association of Ghana Industries (AGI) database in Accra, Ghana as of December 2018. A purposive sampling technique was also used to select ten (10) directors of research institutions from a total number of nineteen (19) research institutions, (including the CSIRs and public tertiary educational institutions), based in Accra, Ghana. The study site, Accra, Ghana, was chosen because of its thriving SME populations and world-class research institutions. While a probit regression model was used to address only the objective three (3) of the research objectives, a descriptive statistical analysis was used via the usage of the SPSS software to generate the mean, standard deviation and percentages on the trend and distribution of the study variables among the study population. However, thematic analysis which enables the examination of the data to identify common themes was used on the qualitative data. The empirical results from the study indicated that technological innovation received from research institutions did not address SMEs' needs and did not result in products and services needed by the Ghanaian community. The study found low collaboration between research institutions and SMEs; and indicated that policy direction towards research institutions and SMEs' collaboration was the essential factor in boosting the efforts to drive collaborations. The study has made a valuable contribution to knowledge by showcasing a framework for successfully transferring technological innovation from research institutions to iii SMEs. The study also contributes to the Helix and triple helix models of innovation by indicating that the successful transfer of technological innovation goes beyond the production of basic research by research institutions and the adoption of basic research by SMEs. Thus, successful technological innovation transfer hinges mainly on effective collaboration between the parties involved. In this regard, the study also contributes to theory, as it is one of the first studies to directly address the problem concerning how the transfer of technological innovation from research institutions to SMEs could enable SMEs thrive and improve the socio-economic development of the Ghanaian economy. The study could enable policymakers/governments to understand the existing gap between research institutions and SMEs and how they can work together to harness technological innovation for the betterment of socio-economic development in Ghana. It also generates new empirical knowledge on research and SMEs. The new knowledge in technological innovations could shape theory and policy decision-making, resulting in enhanced sustainable socio-economic development in Ghana. , Thesis (PhD) -- Faculty of Business and Economic Sciences, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Anoku, John Kofie
- Date: 2023-04
- Subjects: Developing economies , Research & development
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/60537 , vital:65643
- Description: The importance of technological innovation transfer to a country’s socio-economic development cannot be underestimated. This is because technological innovation provides the base for today’s knowledge-based economy. As a developing economy, Ghana faces several socio-economic development challenges as those of other developing economies. Despite these socio-economic challenges, it has been shown that thriving Small and Medium Size Enterprises (SMEs) in Ghana, could help improve the socio-economic development of the Ghanaian economy. Notwithstanding the valuable contributions of SMEs to socio-economic development in Ghana, there appears to be a more significant disconnect between research outcomes from research institutions to SMEs in the areas of technological innovation transfer. It appears there is no bridge between research institutions and SMEs. Against this backdrop, the study aimed at investigating how the transfer of technological innovation from research institutions to SMEs could enable SMEs to thrive and improve the socio-economic development of the Ghanaian economy. A mixed methods research approach was used for the study. The study applied a stratified sampling technique to select 432 CEOs of SMEs from a total population of 481CEOs which represents all CEOs of SMEs in the Association of Ghana Industries (AGI) database in Accra, Ghana as of December 2018. A purposive sampling technique was also used to select ten (10) directors of research institutions from a total number of nineteen (19) research institutions, (including the CSIRs and public tertiary educational institutions), based in Accra, Ghana. The study site, Accra, Ghana, was chosen because of its thriving SME populations and world-class research institutions. While a probit regression model was used to address only the objective three (3) of the research objectives, a descriptive statistical analysis was used via the usage of the SPSS software to generate the mean, standard deviation and percentages on the trend and distribution of the study variables among the study population. However, thematic analysis which enables the examination of the data to identify common themes was used on the qualitative data. The empirical results from the study indicated that technological innovation received from research institutions did not address SMEs' needs and did not result in products and services needed by the Ghanaian community. The study found low collaboration between research institutions and SMEs; and indicated that policy direction towards research institutions and SMEs' collaboration was the essential factor in boosting the efforts to drive collaborations. The study has made a valuable contribution to knowledge by showcasing a framework for successfully transferring technological innovation from research institutions to iii SMEs. The study also contributes to the Helix and triple helix models of innovation by indicating that the successful transfer of technological innovation goes beyond the production of basic research by research institutions and the adoption of basic research by SMEs. Thus, successful technological innovation transfer hinges mainly on effective collaboration between the parties involved. In this regard, the study also contributes to theory, as it is one of the first studies to directly address the problem concerning how the transfer of technological innovation from research institutions to SMEs could enable SMEs thrive and improve the socio-economic development of the Ghanaian economy. The study could enable policymakers/governments to understand the existing gap between research institutions and SMEs and how they can work together to harness technological innovation for the betterment of socio-economic development in Ghana. It also generates new empirical knowledge on research and SMEs. The new knowledge in technological innovations could shape theory and policy decision-making, resulting in enhanced sustainable socio-economic development in Ghana. , Thesis (PhD) -- Faculty of Business and Economic Sciences, 2023
- Full Text:
- Date Issued: 2023-04
Unleashing the nexus between climate change and food security in rural South Africa: role of three community radio stations in the Eastern Cape Province
- Authors: Bamigboye, Foluke Bosede
- Date: 2023-04
- Subjects: Climatic changes , Food security , South Africa -- Rural conditions
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27325 , vital:66939
- Description: This study investigates the role of Forte FM, Mdantsane FM and Rhodes Music Community Radios in disseminating the different kinds of messages on the nexus between the impacts of climate change and food security in the Eastern Cape Province, South Africa. Therefore, the study aims to investigate how these community radio stations play their informative, educative and entertainment roles regarding climate change and food security awareness programmes to their listeners. The study employed the qualitative research approach and convenience, and non-probability samplings techniques were subsequently used to select samples for this study. In-depth interviews were conducted individually for Forte FM, Mdantsane FM and Rhodes Music community radio programme managers respectively, who serve as the key informants. One focus group discussion each was held with residents of Golf Course, Mdantsane and Grahamstown areas where these radio stations broadcast from, with eight participants in each focus group. The total number of participants for the focus group discussions was 24 participants. The collected data were coded into themes using NVivo 12 software to generate the theme nodes and case nodes as key findings, analysis and then interpreted. The findings of this study confirmed that these three community radio stations do contribute to climate change communication through their programmes that focus on climate change and food security related issues. Another vital finding from the study showed that listeners do benefit immensely from these climate change and food security related programmes of the under-study community radio stations. Hence, listeners physical, social, and cognitive well-being of their climatic environment have been greatly impacted. In the same vein, the findings of this study further revealed that the rural communities who are mostly affected by the impacts of climate change on food security have been well informed and enlightened on the suitable ways to enhance a sustainable food security and climate adaptation system through Forte FM, Mdantsane FM, and Rhodes Music community radio stations. Significantly, this study has been able to come up with two suggested models and the conceptual frameworks, which are the Local Action Adaptive Communication (LAAC) Model and the Indigenous Behavioral Change Conceptual (IBCC) Model. These models are focused on increasing listeners interests, adaptation, and behavioral change on climate change issues. The models are also aimed at ensuring better climate change and food security communication Author. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Bamigboye, Foluke Bosede
- Date: 2023-04
- Subjects: Climatic changes , Food security , South Africa -- Rural conditions
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27325 , vital:66939
- Description: This study investigates the role of Forte FM, Mdantsane FM and Rhodes Music Community Radios in disseminating the different kinds of messages on the nexus between the impacts of climate change and food security in the Eastern Cape Province, South Africa. Therefore, the study aims to investigate how these community radio stations play their informative, educative and entertainment roles regarding climate change and food security awareness programmes to their listeners. The study employed the qualitative research approach and convenience, and non-probability samplings techniques were subsequently used to select samples for this study. In-depth interviews were conducted individually for Forte FM, Mdantsane FM and Rhodes Music community radio programme managers respectively, who serve as the key informants. One focus group discussion each was held with residents of Golf Course, Mdantsane and Grahamstown areas where these radio stations broadcast from, with eight participants in each focus group. The total number of participants for the focus group discussions was 24 participants. The collected data were coded into themes using NVivo 12 software to generate the theme nodes and case nodes as key findings, analysis and then interpreted. The findings of this study confirmed that these three community radio stations do contribute to climate change communication through their programmes that focus on climate change and food security related issues. Another vital finding from the study showed that listeners do benefit immensely from these climate change and food security related programmes of the under-study community radio stations. Hence, listeners physical, social, and cognitive well-being of their climatic environment have been greatly impacted. In the same vein, the findings of this study further revealed that the rural communities who are mostly affected by the impacts of climate change on food security have been well informed and enlightened on the suitable ways to enhance a sustainable food security and climate adaptation system through Forte FM, Mdantsane FM, and Rhodes Music community radio stations. Significantly, this study has been able to come up with two suggested models and the conceptual frameworks, which are the Local Action Adaptive Communication (LAAC) Model and the Indigenous Behavioral Change Conceptual (IBCC) Model. These models are focused on increasing listeners interests, adaptation, and behavioral change on climate change issues. The models are also aimed at ensuring better climate change and food security communication Author. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2023
- Full Text:
- Date Issued: 2023-04
Use of flow reactors for an improved synthesis of Tenofovir derivatives
- Authors: Sonti, Thembela
- Date: 2023-04
- Subjects: Antiviral agents -- South Africa , HIV infections –Treatment
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/61190 , vital:69792
- Description: Tenofovir disoproxil fumarate (TDF) is a prescription drug used to treat and prevent human immunodeficiency virus (HIV) infections. It aids in the reduction of HIV in the body, allowing the immune system to function more effectively. This reduces the risk of HIV complications, such as infections, whilst improving the quality of life. TDF belongs to the nucleotide reverse transcriptase inhibitors category of drugs. These drugs limit the ability of the reverse transcriptase, an enzyme essential for each virus to replicate itself. A reduction in the cost of HIV treatment could improve supply security and make it more accessible to patients in need. Thus, this project aims to use flow technology to achieve a guaranteed supply chain and access. In this thesis, a method for the synthesis of TDF was developed using microreactors starting from the readily available adenine. The method was adapted from the traditional batch synthesis as currently there is no literature on the synthesis of TDF in flow chemistry. The batch methods used for the synthesis of the working standards were successfully translated to flow systems. For the best results to be obtained, optimisation of the reaction temperature, reagent molar equivalents and concentration was critical. From the optimisation studies, an improvement in conversion is evident throughout all stages. The flow synthesis of the first intermediate resulted in a conversion of 100 % in N,N-dimethylformamide in 6 min residence time. This study was conducted at 200 °C, which is higher than the boiling point of the solvent with the aid of a back pressure regulator. A key reagent in the synthesis of tenofovir, namely ((tosyloxy)methyl)phosphonic acid, had to be synthesised and it was successfully produced in 96 % yield. The second intermediate was synthesised through a successful coupling reaction between (R)-9-(2-hydroxypropyl)adenine and ((tosyloxy)methyl)- phosphonic acid, which afforded a 100 % conversion of tenofovir in 20 min total residence time. The multistep synthesis of tenofovir was a success as it afforded a 65 % overall conversion. The prodrug TDF was successfully synthesised at 120 °C with a 30 min residence time, yielding a conversion of 100 %. ii | P a g e This thesis consists of four chapters. Chapter one describes the background on HIV and a literature review on HIV drugs. This chapter also demonstrates flow chemistry and microreactors in detail and different routes for the synthesis of TDF in traditional batch methods. Chapter two provides a detailed methodology for batch synthesis and flow synthesis with analytical data. 1H-NMR, 13C-NMR and FTIR spectroscopy was used to evaluate all the compounds synthesised in this chapter. Chapter three thoroughly discusses the results that were obtained graphically, showing that the flow synthesis gives better yields than batch synthesis. In chapter 4, the conclusion of the whole investigation is stated along with the future work for the preparation of TDF. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Sonti, Thembela
- Date: 2023-04
- Subjects: Antiviral agents -- South Africa , HIV infections –Treatment
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/61190 , vital:69792
- Description: Tenofovir disoproxil fumarate (TDF) is a prescription drug used to treat and prevent human immunodeficiency virus (HIV) infections. It aids in the reduction of HIV in the body, allowing the immune system to function more effectively. This reduces the risk of HIV complications, such as infections, whilst improving the quality of life. TDF belongs to the nucleotide reverse transcriptase inhibitors category of drugs. These drugs limit the ability of the reverse transcriptase, an enzyme essential for each virus to replicate itself. A reduction in the cost of HIV treatment could improve supply security and make it more accessible to patients in need. Thus, this project aims to use flow technology to achieve a guaranteed supply chain and access. In this thesis, a method for the synthesis of TDF was developed using microreactors starting from the readily available adenine. The method was adapted from the traditional batch synthesis as currently there is no literature on the synthesis of TDF in flow chemistry. The batch methods used for the synthesis of the working standards were successfully translated to flow systems. For the best results to be obtained, optimisation of the reaction temperature, reagent molar equivalents and concentration was critical. From the optimisation studies, an improvement in conversion is evident throughout all stages. The flow synthesis of the first intermediate resulted in a conversion of 100 % in N,N-dimethylformamide in 6 min residence time. This study was conducted at 200 °C, which is higher than the boiling point of the solvent with the aid of a back pressure regulator. A key reagent in the synthesis of tenofovir, namely ((tosyloxy)methyl)phosphonic acid, had to be synthesised and it was successfully produced in 96 % yield. The second intermediate was synthesised through a successful coupling reaction between (R)-9-(2-hydroxypropyl)adenine and ((tosyloxy)methyl)- phosphonic acid, which afforded a 100 % conversion of tenofovir in 20 min total residence time. The multistep synthesis of tenofovir was a success as it afforded a 65 % overall conversion. The prodrug TDF was successfully synthesised at 120 °C with a 30 min residence time, yielding a conversion of 100 %. ii | P a g e This thesis consists of four chapters. Chapter one describes the background on HIV and a literature review on HIV drugs. This chapter also demonstrates flow chemistry and microreactors in detail and different routes for the synthesis of TDF in traditional batch methods. Chapter two provides a detailed methodology for batch synthesis and flow synthesis with analytical data. 1H-NMR, 13C-NMR and FTIR spectroscopy was used to evaluate all the compounds synthesised in this chapter. Chapter three thoroughly discusses the results that were obtained graphically, showing that the flow synthesis gives better yields than batch synthesis. In chapter 4, the conclusion of the whole investigation is stated along with the future work for the preparation of TDF. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-04
Validation and adaptation of statistical models based on the SAPS III score to predict in-hospital mortality in a South African ICU
- Authors: Pazi, Sisa
- Date: 2023-04
- Subjects: Police -- South Africa -- Eastern Cape , Statistics – South Africa , Mortality – South Africa
- Language: English
- Type: Doctoral's theses , text
- Identifier: http://hdl.handle.net/10948/61360 , vital:70602
- Description: In-hospital mortality prediction remains an important task in Intensive Care Units (ICUs). In particular, the estimated in-hospital mortality risk is essential to describe case-mix, for research and clinical auditing purposes. Furthermore, in settings with limited hospital resources (e.g beds) such as the South African public health care system, the estimated in-hospital mortality risk is essential for resource allocation and to inform local patient triage guidelines. Commonly used models for prediction of in-hospital mortality in ICU patients includes, but not limited to, the Simplified Acute Physiology Score III (SAPS III). The SAPS III model was developed in 2005. Notably, the SAPS III model was developed without data collected from African based hospitals. Given the general application of the SAPS III model, including benchmarking and quality control, the development of such a model based on local data is of paramount importance. To this end, this study developed a model for prediction of in-hospital mortality based on data collected in a hospital in South Africa. Logistic regression modelling was used to develop the proposed mortality risk assessment model. The results indicated that the proposed model exhibited superior discrimination and classification abilities compared to the SAPS III model. Future research includes the external validation of the proposed model in different hospitals in South Africa. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Pazi, Sisa
- Date: 2023-04
- Subjects: Police -- South Africa -- Eastern Cape , Statistics – South Africa , Mortality – South Africa
- Language: English
- Type: Doctoral's theses , text
- Identifier: http://hdl.handle.net/10948/61360 , vital:70602
- Description: In-hospital mortality prediction remains an important task in Intensive Care Units (ICUs). In particular, the estimated in-hospital mortality risk is essential to describe case-mix, for research and clinical auditing purposes. Furthermore, in settings with limited hospital resources (e.g beds) such as the South African public health care system, the estimated in-hospital mortality risk is essential for resource allocation and to inform local patient triage guidelines. Commonly used models for prediction of in-hospital mortality in ICU patients includes, but not limited to, the Simplified Acute Physiology Score III (SAPS III). The SAPS III model was developed in 2005. Notably, the SAPS III model was developed without data collected from African based hospitals. Given the general application of the SAPS III model, including benchmarking and quality control, the development of such a model based on local data is of paramount importance. To this end, this study developed a model for prediction of in-hospital mortality based on data collected in a hospital in South Africa. Logistic regression modelling was used to develop the proposed mortality risk assessment model. The results indicated that the proposed model exhibited superior discrimination and classification abilities compared to the SAPS III model. Future research includes the external validation of the proposed model in different hospitals in South Africa. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2023
- Full Text:
- Date Issued: 2023-04
Viability of government funded broiler production : lessons from Northern KwaZulu Natal, South Africa
- Mdletshe, Sifiso Themba Clement https://orcid.org/0000-0002-2668-0193
- Authors: Mdletshe, Sifiso Themba Clement https://orcid.org/0000-0002-2668-0193
- Date: 2023-04
- Subjects: Broilers (Chickens) -- Economic aspects , Broilers (Poultry) , Broilers (Chickens) -- Breeding
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27843 , vital:69947
- Description: Generally, rural areas continue to experience high poverty levels and low incomes, which seem to be occasioned by high unemployment rates, limited educational attainments, and devastating floods and droughts. This situation is further exacerbated by increase in crime rates, making livelihoods even more difficult. To mitigate such adverse situations, rural households employ diverse strategies, including maintaining community gardens, one-home-one-garden schemes, as well as livestock and poultry production. The most prevalent livelihood strategy in South Africa or KwaZulu-Natal is broiler production, since it needs less space and a short production cycle compared to other livestock or crop enterprises. At the same time, income is generated over a short period. Besides, the government of KwaZulu Natal has actively intervened in the sector as part of its broader poverty reduction strategy and farmer support programmes. In KwaZulu-Natal Province, the provincial government has been supporting broiler producers for many years. While substantial research work has been done in the province on livelihood strategies, including livestock production on a province-wide basis, there is no information about how successful the broiler production funded by the government has being. Broader concerns about production problems have not been assuaged based on systematic studies and evidence. It is this wise that this study was initiated. The objective is to assess the economic viability of government-funded small-scale broiler projects in the KwaZulu-Natal Province of South Africa and determine the implications for poverty reduction and food security. Data were collected from the government-funded small-scale broiler producers that are residing in Northern KwaZulu-Natal districts uThungulu, Zululand and uMkhanyakude. A total of 75 small-scale broiler projects 25 broiler projects in each district were selected by probability sampling procedure for the interviews. Questionnaires that combined both close-ended and open-ended questions were used to collect primary data, which include production and marketing, as well as the factors that influence the profitability of the small-scale broiler projects. After collection, data were captured and encoded on spreadsheets in Microsoft Excel and exported to Statistical Package for the Social Science (SPSS) software version 26 and STATA for analyses. Descriptive statistics applied include frequencies and means. In addition, a gross margin (GM) and gross profit margin (GPM) analysis were employed to assess the profitability of government-funded small-scale broiler projects. Both profitability and gross margin analyses were used as proxies for farmers’ motivation and incentives to participate in broiler production. Further analyses were conducted to determine the model that best explains the underlying relationships. Initially, the Multiple Linear Regression Model was applied to determine the factors influencing the profitability of government-funded small-scale broiler projects. The indication was that while positive profits were revealed, the system seemed to fall short of its potential. In light of that, it was decided to fit another model to estimate the technical efficiency of the system and gain an understanding of the causes of any inefficiency that might exist in the production system. In that regard, the one-step Stochastic Frontier Model was employed to show that the technical efficiency of broiler production systems in the project area was positively and significantly influenced by flock size, the quantity of feeds and labour costs, while medication played no role possibly because of weak extension coverage. An inefficiency model fitted as part of the one-step model suggested that age, gender and educational level were significant influencers of technical inefficiency, with the possibility that the older the farmers, the more technically inefficient the system possibly because of the strenuousness of commercial poultry production. In addition, it was found that the more educated the farmer, the less inefficient the farm, which conversely means that the system becomes more efficient as the farmer receives more education. The negative coefficient of the gender variable also implies that for farms managed by female farmers, the system was less inefficient, which is more technically efficient, and this can be explained by women’s propensity to be more gentle, caring and sensitive in managing the chickens than their male counterparts. Heteroskedasticity tests and corrections were conducted in the one-step estimation technique to show that variations in the inefficiency term (μ) and the stochastic error term were explained by age and educational level for the most part. Clearly, improvements in the broiler industry in KwaZulu-Natal will depend to a large extent on the knowledge and experience of the farmers and substantial enlargement of the flock size of adequately fed birds. Attention to these elements is expected to have important practical implications for sustainable broiler poultry development and food security in the project area, as well as locations possessing identical features and characteristics. , Thesis (MSci) -- Faculty of Science and Agriculture, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Mdletshe, Sifiso Themba Clement https://orcid.org/0000-0002-2668-0193
- Date: 2023-04
- Subjects: Broilers (Chickens) -- Economic aspects , Broilers (Poultry) , Broilers (Chickens) -- Breeding
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27843 , vital:69947
- Description: Generally, rural areas continue to experience high poverty levels and low incomes, which seem to be occasioned by high unemployment rates, limited educational attainments, and devastating floods and droughts. This situation is further exacerbated by increase in crime rates, making livelihoods even more difficult. To mitigate such adverse situations, rural households employ diverse strategies, including maintaining community gardens, one-home-one-garden schemes, as well as livestock and poultry production. The most prevalent livelihood strategy in South Africa or KwaZulu-Natal is broiler production, since it needs less space and a short production cycle compared to other livestock or crop enterprises. At the same time, income is generated over a short period. Besides, the government of KwaZulu Natal has actively intervened in the sector as part of its broader poverty reduction strategy and farmer support programmes. In KwaZulu-Natal Province, the provincial government has been supporting broiler producers for many years. While substantial research work has been done in the province on livelihood strategies, including livestock production on a province-wide basis, there is no information about how successful the broiler production funded by the government has being. Broader concerns about production problems have not been assuaged based on systematic studies and evidence. It is this wise that this study was initiated. The objective is to assess the economic viability of government-funded small-scale broiler projects in the KwaZulu-Natal Province of South Africa and determine the implications for poverty reduction and food security. Data were collected from the government-funded small-scale broiler producers that are residing in Northern KwaZulu-Natal districts uThungulu, Zululand and uMkhanyakude. A total of 75 small-scale broiler projects 25 broiler projects in each district were selected by probability sampling procedure for the interviews. Questionnaires that combined both close-ended and open-ended questions were used to collect primary data, which include production and marketing, as well as the factors that influence the profitability of the small-scale broiler projects. After collection, data were captured and encoded on spreadsheets in Microsoft Excel and exported to Statistical Package for the Social Science (SPSS) software version 26 and STATA for analyses. Descriptive statistics applied include frequencies and means. In addition, a gross margin (GM) and gross profit margin (GPM) analysis were employed to assess the profitability of government-funded small-scale broiler projects. Both profitability and gross margin analyses were used as proxies for farmers’ motivation and incentives to participate in broiler production. Further analyses were conducted to determine the model that best explains the underlying relationships. Initially, the Multiple Linear Regression Model was applied to determine the factors influencing the profitability of government-funded small-scale broiler projects. The indication was that while positive profits were revealed, the system seemed to fall short of its potential. In light of that, it was decided to fit another model to estimate the technical efficiency of the system and gain an understanding of the causes of any inefficiency that might exist in the production system. In that regard, the one-step Stochastic Frontier Model was employed to show that the technical efficiency of broiler production systems in the project area was positively and significantly influenced by flock size, the quantity of feeds and labour costs, while medication played no role possibly because of weak extension coverage. An inefficiency model fitted as part of the one-step model suggested that age, gender and educational level were significant influencers of technical inefficiency, with the possibility that the older the farmers, the more technically inefficient the system possibly because of the strenuousness of commercial poultry production. In addition, it was found that the more educated the farmer, the less inefficient the farm, which conversely means that the system becomes more efficient as the farmer receives more education. The negative coefficient of the gender variable also implies that for farms managed by female farmers, the system was less inefficient, which is more technically efficient, and this can be explained by women’s propensity to be more gentle, caring and sensitive in managing the chickens than their male counterparts. Heteroskedasticity tests and corrections were conducted in the one-step estimation technique to show that variations in the inefficiency term (μ) and the stochastic error term were explained by age and educational level for the most part. Clearly, improvements in the broiler industry in KwaZulu-Natal will depend to a large extent on the knowledge and experience of the farmers and substantial enlargement of the flock size of adequately fed birds. Attention to these elements is expected to have important practical implications for sustainable broiler poultry development and food security in the project area, as well as locations possessing identical features and characteristics. , Thesis (MSci) -- Faculty of Science and Agriculture, 2023
- Full Text:
- Date Issued: 2023-04
Visitors' perceptions of the Outeniqua farmers' market in George
- Authors: Oberholzer, Cornelis
- Date: 2023-04
- Subjects: Farmers' Market -- George , Sustainable Development , Garden Route (South Africa)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/60729 , vital:66486
- Description: Sustainability has been the focal point of sustainable tourism development in South Africa for a number of years. The ability of attractions to depict the culture of an area and provide visitors with locally produced goods that remain economically viable for vendors, remains crucial for tourism development. Hence, farmers’ markets have recently been identified as potential visitor attractions that can provide sustainable development for communities. However, farmers’ markets and their clientele who attend have not received the necessary scholarly attention particularly within the Western Cape region of South Africa. To further understand what role farmers markets can play in the tourism economy; this study sought to examine the perceptions of visitors at the Outeniqua Farmers’ Market in George. The research objectives were: • To determine the demographic profile of visitors to the Outeniqua Farmers’ Market. • To ascertain the preferences of visitors with regard to the type of products offered at the Outeniqua Farmers’ Market. • To determine whether the Outeniqua Farmers’ Market serves as an attraction to visitors. • To analyse which factors motivate visitors to attend the Outeniqua Farmers’ Market. • To examine the visitors understanding of the impact of COVID-19 pandemic on the Outeniqua Farmers’ Market. To accomplish the objectives of this study, previous research undertaken was consulted in order to better understand how farmers’ markets were performing around the world. In addition, to what methodological approaches would be most appropriate to utilise for such a study. The literature consulted revealed disparate differences in perceptions between farmers’ market visitors in Northern as opposed to Southern hemisphere countries. The effects of COVID 19 and the influence of visitor perceptions on travel behaviour were expounded on. Also, previous research revealed that a quantitative survey would be useful for the study as respondents would be accessible at the farmers’ market to solicit information since it was a confined area. v The findings revealed that visitors were mostly locals to the area, comprising primarily white middle-aged females who often attend with family groups. Furthermore, visitors thoroughly enjoyed the overall experience the market presented. It is further complemented by the availability of ready-to-eat foods as well as the provision of social interactions within a secure environment, while scrutinising the environmental friendliness and uniqueness of the products. , Thesis (MA) -- Faculty of Business and Economic Science, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Oberholzer, Cornelis
- Date: 2023-04
- Subjects: Farmers' Market -- George , Sustainable Development , Garden Route (South Africa)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/60729 , vital:66486
- Description: Sustainability has been the focal point of sustainable tourism development in South Africa for a number of years. The ability of attractions to depict the culture of an area and provide visitors with locally produced goods that remain economically viable for vendors, remains crucial for tourism development. Hence, farmers’ markets have recently been identified as potential visitor attractions that can provide sustainable development for communities. However, farmers’ markets and their clientele who attend have not received the necessary scholarly attention particularly within the Western Cape region of South Africa. To further understand what role farmers markets can play in the tourism economy; this study sought to examine the perceptions of visitors at the Outeniqua Farmers’ Market in George. The research objectives were: • To determine the demographic profile of visitors to the Outeniqua Farmers’ Market. • To ascertain the preferences of visitors with regard to the type of products offered at the Outeniqua Farmers’ Market. • To determine whether the Outeniqua Farmers’ Market serves as an attraction to visitors. • To analyse which factors motivate visitors to attend the Outeniqua Farmers’ Market. • To examine the visitors understanding of the impact of COVID-19 pandemic on the Outeniqua Farmers’ Market. To accomplish the objectives of this study, previous research undertaken was consulted in order to better understand how farmers’ markets were performing around the world. In addition, to what methodological approaches would be most appropriate to utilise for such a study. The literature consulted revealed disparate differences in perceptions between farmers’ market visitors in Northern as opposed to Southern hemisphere countries. The effects of COVID 19 and the influence of visitor perceptions on travel behaviour were expounded on. Also, previous research revealed that a quantitative survey would be useful for the study as respondents would be accessible at the farmers’ market to solicit information since it was a confined area. v The findings revealed that visitors were mostly locals to the area, comprising primarily white middle-aged females who often attend with family groups. Furthermore, visitors thoroughly enjoyed the overall experience the market presented. It is further complemented by the availability of ready-to-eat foods as well as the provision of social interactions within a secure environment, while scrutinising the environmental friendliness and uniqueness of the products. , Thesis (MA) -- Faculty of Business and Economic Science, 2023
- Full Text:
- Date Issued: 2023-04
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
Workplace Discrimination Based on Pregnancy
- Authors: Pathiswa, Mbongwana
- Date: 2023-04
- Subjects: Employment discrimination , Pregnancy
- Language: English
- Type: Master's theses , Thesis
- Identifier: http://hdl.handle.net/10948/60797 , vital:67819
- Description: In the past, South Africa was marked by widespread discriminatory practices, many of which still exist to date. This study investigates the persistent discrimination against pregnant women. The study revealed that in South Africa, pregnant women continue to face discrimination in employment and are often denied the right to go on maternity leave, nursing or breastfeeding and childcare facilities. Presently, pregnancy is listed as a prohibited ground for discrimination in the South African Constitution as well as many ILO Conventions. Similarly, the South African labour law framework which gives effect to the Constitution provides for the protection of women and pregnant workers. This protection comes in the form of measures that proscribe dismissal and discrimination based on. Despite these legislation, this study finds that the less favorable treatment of women and pregnant workers in South African workplaces has become increasingly common, and this has turned into a contentious subject. This study focused on labour legislation that has been developed to safeguard pregnant women in the workplace in light of applicable constitutional protections. Notwithstanding these legislative protections for pregnant women in the workplace, the analysis shows that many pregnant women continue to be treated unfairly due to their pregnancies or for reasons linked to their pregnancies. Consequently, there has been a regression in the actual execution of laws and regulations protecting pregnant workers. The study highlights the need to establish mechanisms to ensure that legislation protecting pregnant workers in the workplace achieves its intended purpose and is implemented properly. Consequently, this study presents pertinent suggestions about the implementation of labour legislation so that the employment rights of women and pregnant workers are adequately safeguarded. , Thesis (LLB) -- Faculty of Law, School of Mercantile Law, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Pathiswa, Mbongwana
- Date: 2023-04
- Subjects: Employment discrimination , Pregnancy
- Language: English
- Type: Master's theses , Thesis
- Identifier: http://hdl.handle.net/10948/60797 , vital:67819
- Description: In the past, South Africa was marked by widespread discriminatory practices, many of which still exist to date. This study investigates the persistent discrimination against pregnant women. The study revealed that in South Africa, pregnant women continue to face discrimination in employment and are often denied the right to go on maternity leave, nursing or breastfeeding and childcare facilities. Presently, pregnancy is listed as a prohibited ground for discrimination in the South African Constitution as well as many ILO Conventions. Similarly, the South African labour law framework which gives effect to the Constitution provides for the protection of women and pregnant workers. This protection comes in the form of measures that proscribe dismissal and discrimination based on. Despite these legislation, this study finds that the less favorable treatment of women and pregnant workers in South African workplaces has become increasingly common, and this has turned into a contentious subject. This study focused on labour legislation that has been developed to safeguard pregnant women in the workplace in light of applicable constitutional protections. Notwithstanding these legislative protections for pregnant women in the workplace, the analysis shows that many pregnant women continue to be treated unfairly due to their pregnancies or for reasons linked to their pregnancies. Consequently, there has been a regression in the actual execution of laws and regulations protecting pregnant workers. The study highlights the need to establish mechanisms to ensure that legislation protecting pregnant workers in the workplace achieves its intended purpose and is implemented properly. Consequently, this study presents pertinent suggestions about the implementation of labour legislation so that the employment rights of women and pregnant workers are adequately safeguarded. , Thesis (LLB) -- Faculty of Law, School of Mercantile Law, 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