Development and optimisation of a mucoadhesive chitosan-based intranasal microemulsion and nanomicelle solution for lamotrigine using artificial neural networks
- Authors: Melamane, Siyabonga
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/${Handle} , vital:45247
- Description: Thesis (PhD) -- Faculty of Science, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Melamane, Siyabonga
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/${Handle} , vital:45247
- Description: Thesis (PhD) -- Faculty of Science, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-10-29
Distribution, ecological and economic impacts and competition of the invasive alien aquatic weeds (Pontederia crassipes Mart., Pistia stratiotes L., Salvinia molesta D.S. Mitch. and Azolla filiculoides Lam.) in Madagascar
- Authors: Lehavana, Adolphe
- Date: 2021-10-29
- Subjects: Pontederiaceae Madagascar , Water lettuce Madagascar , Salvinia molesta Madagascar , Azolla filiculoides Madagascar , Introduced aquatic organisms , Aquatic weeds Economic aspects , Aquatic weeds Social aspects , Aquatic weeds Geographical distribution
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191225 , vital:45072
- Description: In Madagascar, as in several countries in the world, the invasion by four aquatic weeds (Pontederia crassipes Mart. (Pontederiaceae), Pistia stratiotes L. (Araceae), Salvinia molesta D.S. Mitch Salviniaceae) and Azolla filiculoides Lam. (Azollaceae) are among the drivers of environmental and socio-economic deterioration in aquatic ecosystems. Pistia stratiotes was first recorded on the island in the 19th century, and P. crassipes from the beginning of the 20th century, while S. molesta and A. filiculoides were only documented during in the 21st century. From the 1920s, botanists such as Henri Perrier de la Bathie and Raymond Decary were already aware of the dangers caused, in particular by P. crassipes in other countries, and raised the alarm, but little attention has been paid to these species. The aim of the research conducted for this thesis was to determine the distribution, socio-economic and ecological impacts of these four invasive alien aquatic weeds in Madagascar and to make recommendations for their control. First, the distributions of these four aquatic weeds were mapped. This mapping exercise compiled data from different sources including herbarium records, online data and field visits across Madagascar. The mapping study was undertaken from August 2015 to June 2020. Except for mountainous areas above 1800 m (Tsaratanana Massif, Ankaratra Massif and Andringitra Massif) where no data were available, all of Madagascar's bioclimates were invaded by at least one of the four aquatic weeds. In total, at least one species was recorded in 18 of the 22 Regions. Pontederia crassipes was recorded in 13 Regions, S. molesta in 14 Regions, P. stratiotes in 12 Regions, and A. filiculoides in 13 Regions. Herbarium records revealed the oldest record for P. stratiotes to be 1847, 1931 for P. crassipes, 1995 for S. molesta and there were no herbarium specimens for A. filiculoides prior to the start of the current study in 2015. We now know where these four weeds occur and how abundant they are. An objective of this research was to assess the impacts of the four invasive aquatic plants on the socio-economy of the island, mainly on rice production and fishing. Between 2016 and 2019, 102 households in three regions, Soanierana Ivongo, Foulpointe and Antananarivo, were randomly selected and questioned on the impact of these weeds in their aquatic ecosystems and their livelihoods such as fishing and rice growing. Surveys revealed that the four aquatic weeds significantly threatened household activities. On the east coast of Madagascar, the invasions of these four invasive species decreased fish and freshwater shrimp production by 82%. On the high plateau of Madagascar, they reduced rice yield by 30% despite requiring an additional expense of US$ 1,107/ha for control. Although farmers surveyed only used manual control to manage these weeds, they were receptive to other control methods, including integrated control using herbicides and biological control. Another objective of this research was to determine the ecological impacts of the four weeds and specifically if freshwater ecosystem functioning would return after control. To assess the ecological impact, between February 2017 to August 2019, on Lake Antsokafina, the following abiotic and biotic factors were considered: physico-chemistry of water, succession of macrophyte community and animal diversity. With the exception of turbidity, the values of the physico-chemical parameters of the water (pH, electrical conductivity, water temperature and turbidity), were similar between the infested zone and cleared zone. A study on the invasion process of aquatic weeds showed that the plant community succession of the lake changed over time in the areas that had been cleared. The submerged species Ceratophyllum demersum was the pioneer, followed by creeping species such as Echinochloa colona and Ipomoea aquatica, before the area was recolonized by aquatic weeds. Among the aquatic weeds, S. molesta was the most aggressive, covering 92% of the area one year after the start of the experiment. For animal diversity, bird, shrimp and fish community were assessed. The cleaning of the plots in the lake allowed the resumption of fishing activity providing 50 to 200g/catch for shrimp and from 0.25 to 0.5kg/catch for fish per person per day, while no catch was obtained in the areas infested by aquatic weeds were fishermen still attempting to harvest fish/shrimp from the aquatic weed infested areas. Three species of birds, Humblot’s Heron (Ardea humbloti), the white-faced whistling duck (Dendrocygna viduata) and red-billed teal (Anas erythrorhyncha) returned once the areas had been cleared. A manipulated outdoor as descriptor for laboratory experiment was conducted to determine the level and nature of competition of four aquatic weeds species against the indigenous floating fern, Salvinia hastata Desv. (Salviniaceae), using an additive series density model. It was shown that all four invasive species outcompeted S. hastata, with P. crassipes being 24 times more dominant, followed by P. stratiotes at 12 times, S. molesta at 8 times, and finally A. filiculoides at 1.2 times more dominant. This study provided direct evidence of the biodiversity impact of these four species and thus also provided an environmental argument for their control. Based on the findings of this study, a series of recommendations was formulated to manage the invasions of alien species in Madagascar with particular attention to invasive aquatic weeds. These recommendations mainly concern the establishment of management structures and legal instruments such as the creation of a lead government agency at national level and a cross-sectorial invasive species advisory committee, which should review legislation and regulations related to invasive species. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Lehavana, Adolphe
- Date: 2021-10-29
- Subjects: Pontederiaceae Madagascar , Water lettuce Madagascar , Salvinia molesta Madagascar , Azolla filiculoides Madagascar , Introduced aquatic organisms , Aquatic weeds Economic aspects , Aquatic weeds Social aspects , Aquatic weeds Geographical distribution
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191225 , vital:45072
- Description: In Madagascar, as in several countries in the world, the invasion by four aquatic weeds (Pontederia crassipes Mart. (Pontederiaceae), Pistia stratiotes L. (Araceae), Salvinia molesta D.S. Mitch Salviniaceae) and Azolla filiculoides Lam. (Azollaceae) are among the drivers of environmental and socio-economic deterioration in aquatic ecosystems. Pistia stratiotes was first recorded on the island in the 19th century, and P. crassipes from the beginning of the 20th century, while S. molesta and A. filiculoides were only documented during in the 21st century. From the 1920s, botanists such as Henri Perrier de la Bathie and Raymond Decary were already aware of the dangers caused, in particular by P. crassipes in other countries, and raised the alarm, but little attention has been paid to these species. The aim of the research conducted for this thesis was to determine the distribution, socio-economic and ecological impacts of these four invasive alien aquatic weeds in Madagascar and to make recommendations for their control. First, the distributions of these four aquatic weeds were mapped. This mapping exercise compiled data from different sources including herbarium records, online data and field visits across Madagascar. The mapping study was undertaken from August 2015 to June 2020. Except for mountainous areas above 1800 m (Tsaratanana Massif, Ankaratra Massif and Andringitra Massif) where no data were available, all of Madagascar's bioclimates were invaded by at least one of the four aquatic weeds. In total, at least one species was recorded in 18 of the 22 Regions. Pontederia crassipes was recorded in 13 Regions, S. molesta in 14 Regions, P. stratiotes in 12 Regions, and A. filiculoides in 13 Regions. Herbarium records revealed the oldest record for P. stratiotes to be 1847, 1931 for P. crassipes, 1995 for S. molesta and there were no herbarium specimens for A. filiculoides prior to the start of the current study in 2015. We now know where these four weeds occur and how abundant they are. An objective of this research was to assess the impacts of the four invasive aquatic plants on the socio-economy of the island, mainly on rice production and fishing. Between 2016 and 2019, 102 households in three regions, Soanierana Ivongo, Foulpointe and Antananarivo, were randomly selected and questioned on the impact of these weeds in their aquatic ecosystems and their livelihoods such as fishing and rice growing. Surveys revealed that the four aquatic weeds significantly threatened household activities. On the east coast of Madagascar, the invasions of these four invasive species decreased fish and freshwater shrimp production by 82%. On the high plateau of Madagascar, they reduced rice yield by 30% despite requiring an additional expense of US$ 1,107/ha for control. Although farmers surveyed only used manual control to manage these weeds, they were receptive to other control methods, including integrated control using herbicides and biological control. Another objective of this research was to determine the ecological impacts of the four weeds and specifically if freshwater ecosystem functioning would return after control. To assess the ecological impact, between February 2017 to August 2019, on Lake Antsokafina, the following abiotic and biotic factors were considered: physico-chemistry of water, succession of macrophyte community and animal diversity. With the exception of turbidity, the values of the physico-chemical parameters of the water (pH, electrical conductivity, water temperature and turbidity), were similar between the infested zone and cleared zone. A study on the invasion process of aquatic weeds showed that the plant community succession of the lake changed over time in the areas that had been cleared. The submerged species Ceratophyllum demersum was the pioneer, followed by creeping species such as Echinochloa colona and Ipomoea aquatica, before the area was recolonized by aquatic weeds. Among the aquatic weeds, S. molesta was the most aggressive, covering 92% of the area one year after the start of the experiment. For animal diversity, bird, shrimp and fish community were assessed. The cleaning of the plots in the lake allowed the resumption of fishing activity providing 50 to 200g/catch for shrimp and from 0.25 to 0.5kg/catch for fish per person per day, while no catch was obtained in the areas infested by aquatic weeds were fishermen still attempting to harvest fish/shrimp from the aquatic weed infested areas. Three species of birds, Humblot’s Heron (Ardea humbloti), the white-faced whistling duck (Dendrocygna viduata) and red-billed teal (Anas erythrorhyncha) returned once the areas had been cleared. A manipulated outdoor as descriptor for laboratory experiment was conducted to determine the level and nature of competition of four aquatic weeds species against the indigenous floating fern, Salvinia hastata Desv. (Salviniaceae), using an additive series density model. It was shown that all four invasive species outcompeted S. hastata, with P. crassipes being 24 times more dominant, followed by P. stratiotes at 12 times, S. molesta at 8 times, and finally A. filiculoides at 1.2 times more dominant. This study provided direct evidence of the biodiversity impact of these four species and thus also provided an environmental argument for their control. Based on the findings of this study, a series of recommendations was formulated to manage the invasions of alien species in Madagascar with particular attention to invasive aquatic weeds. These recommendations mainly concern the establishment of management structures and legal instruments such as the creation of a lead government agency at national level and a cross-sectorial invasive species advisory committee, which should review legislation and regulations related to invasive species. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10-29
Embodied difference in manhood: A sociological analysis of the intersection of visible physical impairments and manhood among Xhosa men in the Eastern Cape
- Authors: Sipungu, Thoko Andy
- Date: 2021-10-29
- Subjects: Masculinity South Africa Eastern Cape , Sex role South Africa Eastern Cape , Sex role Psychological aspects , Men with disabilities South Africa Eastern Cape , People with disabilities Social conditions , Xhosa (African people) South Africa Eastern Cape Social life and customs , Male domination (Social structure) South Africa Eastern Cape , Circumcision Social aspects South Africa Eastern Cape
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191658 , vital:45145 , 10.21504/10962/191658
- Description: In this thesis, I outline possible answers to the question of what it means to be a Xhosa man living with a visible physical impairment. Drawing on 17 one-on-one in-depth interviews and through an interpretive phenomenological thematic analysis, this thesis explores the intersection of physical disabilities and manhood masculinity in Xhosa men in selected rural areas in the Eastern Cape, South Africa. The intention for this study is to better our understanding concerning the creation, negotiation, maintenance, and recreation of manhood identities by traditionally circumcised Xhosa men in the Eastern Cape who by birth, accident, or illness find themselves at the intersections of masculinity and physical disability. Research notes that the bodies of men with disabilities serve as a continual reminder that they are at odds with the expectations of the dominant manhood cultures. The main argument from this area of research is that men with disabilities are outside the hegemony because they undermine the normative role and shape of the body in Western cultures. However, this line of argumentation stands in sharp contrast to arguments that the hegemony in Xhosa manhood masculinity is primarily and conclusively achieved by having a traditionally circumcised penis without any consideration of the full embodiments of men. Therefore, this study, in the first instance, seeks to bring embodiment into the analyses of manhood by focusing on physical disability amongst traditionally circumcised Xhosa men. Through an embodied theoretical approach to their disabilities that accounts for the corporeal experience of impairment, and theories of masculinity that centre the context, this thesis establishes, in the first instance, the significance of embodiment in doing Xhosa manhood. Concerning the research aims and objectives, this study sheds light on what it means to be a Xhosa man living with visible physical impairment. In this regard, the original findings are classified according to each research aims and objective, as outlined below. Concerning the first research aim, I found that the participants struggle to speak about their bodies outside of physical labour/work despite their impairments. I explain their inability to talk about their disabled bodies by looking at traditional Xhosa initiation as a grantor of equality and sameness. Secondly, I argue that there is a higher premium on social bodies rather than physical bodies in this context, thus their inability to speak about their conditions. Lastly, I make connections between the participants’ inabilities to talk about their bodies and the lasting impact of colonial and apartheid histories. Concerning the second research aim, I explore ways and strategies they employ to respond to and negotiate Xhosa manhood masculinity's dominant cultural demands. In this regard, I note that the participants who acquired their impairments after initiation consider their disability as a second initiation because they see it as having set them back to square one regarding their manhood responsibilities. In contrast, the participants who acquired their disabilities post-initiation saw initiation as a gateway to a more respectable personhood status. I also note that there is an emergence of alternative Xhosa manhood masculinities. Lastly, I also found that contrary to western scholarship on disability and manhood, the participants distinguish between threatened manhood identity versus threatened status as a man. I outline how they arrive at this distinction. In terms of researching the last research aim, this thesis explores how the participants negotiate their ‘embodied difference’ in mundane everyday living. I explore their taken-for-granted routines in doing and being disabled Xhosa men every day. In this regard, this study presents original and interesting findings regarding sex and intimacy, social interactions and sociability, and everyday home living. , Thesis (PhD) -- Faculty of Humanities, Sociology, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Sipungu, Thoko Andy
- Date: 2021-10-29
- Subjects: Masculinity South Africa Eastern Cape , Sex role South Africa Eastern Cape , Sex role Psychological aspects , Men with disabilities South Africa Eastern Cape , People with disabilities Social conditions , Xhosa (African people) South Africa Eastern Cape Social life and customs , Male domination (Social structure) South Africa Eastern Cape , Circumcision Social aspects South Africa Eastern Cape
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191658 , vital:45145 , 10.21504/10962/191658
- Description: In this thesis, I outline possible answers to the question of what it means to be a Xhosa man living with a visible physical impairment. Drawing on 17 one-on-one in-depth interviews and through an interpretive phenomenological thematic analysis, this thesis explores the intersection of physical disabilities and manhood masculinity in Xhosa men in selected rural areas in the Eastern Cape, South Africa. The intention for this study is to better our understanding concerning the creation, negotiation, maintenance, and recreation of manhood identities by traditionally circumcised Xhosa men in the Eastern Cape who by birth, accident, or illness find themselves at the intersections of masculinity and physical disability. Research notes that the bodies of men with disabilities serve as a continual reminder that they are at odds with the expectations of the dominant manhood cultures. The main argument from this area of research is that men with disabilities are outside the hegemony because they undermine the normative role and shape of the body in Western cultures. However, this line of argumentation stands in sharp contrast to arguments that the hegemony in Xhosa manhood masculinity is primarily and conclusively achieved by having a traditionally circumcised penis without any consideration of the full embodiments of men. Therefore, this study, in the first instance, seeks to bring embodiment into the analyses of manhood by focusing on physical disability amongst traditionally circumcised Xhosa men. Through an embodied theoretical approach to their disabilities that accounts for the corporeal experience of impairment, and theories of masculinity that centre the context, this thesis establishes, in the first instance, the significance of embodiment in doing Xhosa manhood. Concerning the research aims and objectives, this study sheds light on what it means to be a Xhosa man living with visible physical impairment. In this regard, the original findings are classified according to each research aims and objective, as outlined below. Concerning the first research aim, I found that the participants struggle to speak about their bodies outside of physical labour/work despite their impairments. I explain their inability to talk about their disabled bodies by looking at traditional Xhosa initiation as a grantor of equality and sameness. Secondly, I argue that there is a higher premium on social bodies rather than physical bodies in this context, thus their inability to speak about their conditions. Lastly, I make connections between the participants’ inabilities to talk about their bodies and the lasting impact of colonial and apartheid histories. Concerning the second research aim, I explore ways and strategies they employ to respond to and negotiate Xhosa manhood masculinity's dominant cultural demands. In this regard, I note that the participants who acquired their impairments after initiation consider their disability as a second initiation because they see it as having set them back to square one regarding their manhood responsibilities. In contrast, the participants who acquired their disabilities post-initiation saw initiation as a gateway to a more respectable personhood status. I also note that there is an emergence of alternative Xhosa manhood masculinities. Lastly, I also found that contrary to western scholarship on disability and manhood, the participants distinguish between threatened manhood identity versus threatened status as a man. I outline how they arrive at this distinction. In terms of researching the last research aim, this thesis explores how the participants negotiate their ‘embodied difference’ in mundane everyday living. I explore their taken-for-granted routines in doing and being disabled Xhosa men every day. In this regard, this study presents original and interesting findings regarding sex and intimacy, social interactions and sociability, and everyday home living. , Thesis (PhD) -- Faculty of Humanities, Sociology, 2021
- Full Text:
- Date Issued: 2021-10-29
Establishing a water resources assessment system for Eswatini (Swaziland) incorporating data and modelling uncertainty
- Authors: Ndzabandzaba, Coli
- Date: 2021-10-29
- Subjects: Water resources development Eswatini , Water-supply Eswatini Management , Hydrologic models Eswatini , Runoff Mathematical models , Rain and rainfall Mathematical models , Pitman model
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/189009 , vital:44806 , 10.21504/10962/189009
- Description: The uneven distribution of water resources availability globally puts pressure on environmental and human or socio-economic systems and has complex implications for the interactions within these systems. The natural environment and water resources are increasingly threatened by development, and water management crises are still occurring. This is exacerbated by the lack of accurate and adequate information on these systems. In Eswatini, for example, the pressure on the available water resources is mounting due to increasing water demand for irrigation while information about natural hydrological conditions and levels of water resources developments are uncertain. In addition, the practical application of hydrological models for water resources assessments that incorporate uncertainty in Eswatini has yet to be realised. The aim of the study, therefore, was to develop a water resource assessment system that is based on both observed and simulated information and that includes uncertainty. This study focusses on a regional water resource assessment using an uncertainty version of the Pitman monthly rainfall-runoff model whose outputs are constrained by six indices of natural hydrological response (i.e., mean monthly runoff, mean monthly groundwater recharge, Q10, Q50 and Q90 percentage points of the flow duration curve and % time of zero flows) for each of the 122 sub-basins of the transboundary catchments of Eswatini. A 2-step uncertainty modelling approach was tested, validated and then applied to all the sub-basins of Eswatini. The first step of the model run establishes behavioural, but uncertain model parameter ranges for natural incremental sub-basin hydrological responses and the model is typically run 100 000 times for each sub-basin. The parameter space that defines the uncertainty in parameter estimation is sampled based on simple Monte Carlo approach. The second step links all the sub-basin outputs and allows for water use parameters to be incorporated, where necessary, in order to generate cumulative sub-basin outflows. The results from the constraint index analysis have proved to be useful in constraining the model outputs. Generally, the behavioural model outputs produced realistic uncertainty estimates as well as acceptable simulations based on the assessment of the flow duration curves. The modelling results indicated that there is some degree of uncertainty that cannot be easily accounted for due to some identified data issues. The results also showed that there is still a possibility to improve the simulations provided such issues are resolved. The issues about the simulation of stream flow that were detected are mainly related to availability of data to estimate water use parameters. Another challenge in setting up the model was associated with establishing constraints that match the parameters for natural hydrological conditions for specific sub-basins and maintaining consistency in the adjustment of the model output constraints for other sub-basins. In an attempt to overcome this problem, the study recommends additional hydrological response constraints to be used with the Pitman model. Another main recommendation relates to the strong cooperation of relevant catchment management authorities and stakeholders including scientists in order to make information more available to users. The new hydrological insight is derived from the analysis of hydrological indices which highlighted the regional variations in hydrological processes and sub-basin response across the transboundary basins of Eswatini. The adopted modelling approach provides further insight into all the uncertainties associated with quantifying the available water resources of the country. The study has provided further understanding of the spatial variability of the hydrological response and existing development impacts than was previously available. It is envisaged that these new insights will provide an improved basis for future water management in Eswatini. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Ndzabandzaba, Coli
- Date: 2021-10-29
- Subjects: Water resources development Eswatini , Water-supply Eswatini Management , Hydrologic models Eswatini , Runoff Mathematical models , Rain and rainfall Mathematical models , Pitman model
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/189009 , vital:44806 , 10.21504/10962/189009
- Description: The uneven distribution of water resources availability globally puts pressure on environmental and human or socio-economic systems and has complex implications for the interactions within these systems. The natural environment and water resources are increasingly threatened by development, and water management crises are still occurring. This is exacerbated by the lack of accurate and adequate information on these systems. In Eswatini, for example, the pressure on the available water resources is mounting due to increasing water demand for irrigation while information about natural hydrological conditions and levels of water resources developments are uncertain. In addition, the practical application of hydrological models for water resources assessments that incorporate uncertainty in Eswatini has yet to be realised. The aim of the study, therefore, was to develop a water resource assessment system that is based on both observed and simulated information and that includes uncertainty. This study focusses on a regional water resource assessment using an uncertainty version of the Pitman monthly rainfall-runoff model whose outputs are constrained by six indices of natural hydrological response (i.e., mean monthly runoff, mean monthly groundwater recharge, Q10, Q50 and Q90 percentage points of the flow duration curve and % time of zero flows) for each of the 122 sub-basins of the transboundary catchments of Eswatini. A 2-step uncertainty modelling approach was tested, validated and then applied to all the sub-basins of Eswatini. The first step of the model run establishes behavioural, but uncertain model parameter ranges for natural incremental sub-basin hydrological responses and the model is typically run 100 000 times for each sub-basin. The parameter space that defines the uncertainty in parameter estimation is sampled based on simple Monte Carlo approach. The second step links all the sub-basin outputs and allows for water use parameters to be incorporated, where necessary, in order to generate cumulative sub-basin outflows. The results from the constraint index analysis have proved to be useful in constraining the model outputs. Generally, the behavioural model outputs produced realistic uncertainty estimates as well as acceptable simulations based on the assessment of the flow duration curves. The modelling results indicated that there is some degree of uncertainty that cannot be easily accounted for due to some identified data issues. The results also showed that there is still a possibility to improve the simulations provided such issues are resolved. The issues about the simulation of stream flow that were detected are mainly related to availability of data to estimate water use parameters. Another challenge in setting up the model was associated with establishing constraints that match the parameters for natural hydrological conditions for specific sub-basins and maintaining consistency in the adjustment of the model output constraints for other sub-basins. In an attempt to overcome this problem, the study recommends additional hydrological response constraints to be used with the Pitman model. Another main recommendation relates to the strong cooperation of relevant catchment management authorities and stakeholders including scientists in order to make information more available to users. The new hydrological insight is derived from the analysis of hydrological indices which highlighted the regional variations in hydrological processes and sub-basin response across the transboundary basins of Eswatini. The adopted modelling approach provides further insight into all the uncertainties associated with quantifying the available water resources of the country. The study has provided further understanding of the spatial variability of the hydrological response and existing development impacts than was previously available. It is envisaged that these new insights will provide an improved basis for future water management in Eswatini. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-10-29
Ethics of climate change: a normative account
- Authors: Afolabi, Abiodun Paul
- Date: 2021-10-29
- Subjects: Climatic changes Senegal Saint-Louis , Climatic changes Moral and ethical aspects , Cultural property Senegal Saint-Louis , Ethics Senegal Saint-Louis , Applied ethics , Environmental justice Senegal Saint-Louis , Philosophy, African , Normativity (Ethics)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192864 , vital:45272 , 10.21504/10962/192864
- Description: Consider, for instance, you and your family have lived around a place where you enjoyed the flora and fauna of the land as well as the natural environment. Fishing and farming were pleasant activities for your family, and anyone in the community not only to survive but thrive. Your neighbours and the people in the community pride themselves so much in their farming abilities and fishing techniques. Suddenly things start taking a different turn because of rising sea level and changing weather pattern. First, your land began to give way because of sweeping erosion, and later the riverbank serving the community starts drying up. Your neighbour could not hold their own in this grim condition as they started relocating. You even witnessed some of your family and friends leaving the community and you later heard that they have become climate refugees. To put it all together, you were told that what you are experiencing is one of climate change effects. You were told that the loss of the place that you once cherished is not an act of God but the result of the reckless flaring of greenhouse gasses harmful to the environment by some powerful but polluting nations. What will you do? This might sound like a fairy tale. In reality, this is the story of the people of Saint Louis Atlantic Coasts in Senegal, captured by the Global Climate Change Alliance Plus Initiative.1 Their situation has been described as ‘living on the edge’ because for centuries, Saint Louis Atlantic Coasts, home to around 230,000 inhabitants, also known as the ‘Venice of Africa’ has been protected from the pounding Atlantic waves by the ‘Langue de Barbarie,’ a narrow, 30 km peninsula at the mouth of the Senegal river. However, the low-lying sandy spit of land along this World Heritage site is itself rapidly disappearing in the present. This is the consequence of a changing climate and other man-made problems such as illegal sand-mining and over-development. Today, the southern part of the Langue de Barbarie is an island, and the village of Doune Baba Dieye is under more than a metre of water. The villagers have become climate refugees, forced to live in temporary camps on the mainland. Not only have they lost their homes, but they have also lost significant cultural heritage like the farming and fishing culture tied to this place. The ethical considerations that emerge from climate change impacts on the world’s cultural heritage are varied. However, it seems not as self-evident in the way that research on climate change ethics has been framed around economic interest and direct threats to human life and other species. Even when they mention climate impacts on heritage sites around the world, those of Africans have been side-lined. For instance, the impact of climate change on small island nations like Tuvalu, Kiribati2 have gained much traction in climate change discourse, but we do not get to see stories of Africans whose cherished cultural heritage are affected by climate despoliation. How do we respond to this intractable challenge? This is a question of justice and, to be more precise, climate justice. Many principles and proposals for climate justice have been put forward, but the insufficient attention to the vulnerabilities or loss of cultural heritage values of Africans, which is a critical aspect of their social realities, make these theories less persuasive on a global level. This thesis, then, fills this gap in the literature by suggesting that the failure to take cognizance of the injustice in neglecting cultural heritage values when dealing with the burden of climate change is the effect of three problems. One, the value of culture is less understood in this environmental age. Hence, cultural values are excluded or made to be secondary in consideration of principles of climate justice. Second, the idea of Personhood has been neglected in climate ethics and climate justice discourse. Yet, this idea of Personhood can be an enabler of climate justice in that a realization of the significance of cultural heritage to the wellness of the human persons in Africa, makes it loss morally reprehensible. Third, those whose cultural heritage is significantly affected do not get represented in the debate about sharing the burden of climate change. This dissertation thereby builds upon the general findings of the past about anthropogenic climate change, its causes and consequences. Adopting a discursive normative framework, I also address the significance of cultural heritage in this contemporary environmental age and discuss the global justice implications of cultural heritage loss to climate change. This dissertation further provides a critique of mainstream climate justice theories, especially their marginalization of the cultural dimension of climate change. In this regard, the metaphor - ‘cultural storm’ was deployed to argue that climate justice discourses have neither factored the deep socio-cultural impact of climate change nor do they draw on the cultural understanding of justice in putting forward their theories. Given the nature of the indirect, cumulative, and interconnected invisible losses to cultural heritage from climate change, it seems unlikely that they can be addressed by simple tweaks of the climate justice status quo. This dissertation proposes that the idea of personhood in African philosophy, can be conceived to ensure climate justice live up to its expectations in a world of diverse persons dealing with a complex phenomenon like climate change. It argues that a cultural dimension of climate ethics has implications for how mitigation, adaptation and compensation plans should be furthered for global climate justice. At the foundation of my argument, I suggest that what is needed in climate justice discourse is a commitment to explore new and innovative alternatives that will produce an inclusive global climate treaty that is sensitive to the cultural heritage assets that is destroyed by climate change in Africa. This will require a multi-dimensional framework that allows fundamentally different kinds of values and benefits to be given equal visibility and standing in global climate negotiations. The dissertation proceeds in six chapters. In the first chapter, I discuss how climate change denies, damage and destroys cultural heritage values in Africa and argue that it is unjust to ignore this dimension of climate change impact, particularly on the African continent. In the second chapter, I critically discuss the normative value of cultural heritage in an environmentally sustainable and morally appropriate way for this global age. I argue that what is lost when climate change affects cultural heritage is a significant cultural asset that ought to be seriously considered in climate ethics. The third chapter addresses the global justice implications of the destruction of Africa's cultural heritage by climate change that must be paid attention to. In chapter four, I evaluate the plausibility of some of the mainstream climate justice proposals. I offered a different possible critique of current approaches to climate justice to show how they have furthered cultural injustice. The critique of current climate justice theories that I offer, stems from an uninspiring approach that belies logic permitting the sacrificing of that which is connected to others wellbeing as well as the implicit assumptions and the limitation of the idea of justice that undergird these climate justice theories. I offer, in chapter five, a plausible climate ethics theory that recognizes culturally embedded ideas of justice and empower all stakeholders to build by themselves, lives that are, in the light of these ideas, deemed to be adversely impacted by climate change. This theory advances a socio-cultural perspective to climate change which could provide a nuanced basis for understanding and addressing global climate duties that will be sensitive to the loss of cultural heritage. Specifically, I apply the African conception of personhood, to provide a normative basis for a different but intuitive understanding of the cultural dimension of climate ethics. In the final chapter, I discuss how this theory can be applied to rethink current global responses in the form of mitigation, adaptation and compensation in such a way that it takes seriously the impacts of climate change on Africa’s cultural heritage and values. , Thesis (PhD) -- Faculty of Humanities, Philosophy, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Afolabi, Abiodun Paul
- Date: 2021-10-29
- Subjects: Climatic changes Senegal Saint-Louis , Climatic changes Moral and ethical aspects , Cultural property Senegal Saint-Louis , Ethics Senegal Saint-Louis , Applied ethics , Environmental justice Senegal Saint-Louis , Philosophy, African , Normativity (Ethics)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192864 , vital:45272 , 10.21504/10962/192864
- Description: Consider, for instance, you and your family have lived around a place where you enjoyed the flora and fauna of the land as well as the natural environment. Fishing and farming were pleasant activities for your family, and anyone in the community not only to survive but thrive. Your neighbours and the people in the community pride themselves so much in their farming abilities and fishing techniques. Suddenly things start taking a different turn because of rising sea level and changing weather pattern. First, your land began to give way because of sweeping erosion, and later the riverbank serving the community starts drying up. Your neighbour could not hold their own in this grim condition as they started relocating. You even witnessed some of your family and friends leaving the community and you later heard that they have become climate refugees. To put it all together, you were told that what you are experiencing is one of climate change effects. You were told that the loss of the place that you once cherished is not an act of God but the result of the reckless flaring of greenhouse gasses harmful to the environment by some powerful but polluting nations. What will you do? This might sound like a fairy tale. In reality, this is the story of the people of Saint Louis Atlantic Coasts in Senegal, captured by the Global Climate Change Alliance Plus Initiative.1 Their situation has been described as ‘living on the edge’ because for centuries, Saint Louis Atlantic Coasts, home to around 230,000 inhabitants, also known as the ‘Venice of Africa’ has been protected from the pounding Atlantic waves by the ‘Langue de Barbarie,’ a narrow, 30 km peninsula at the mouth of the Senegal river. However, the low-lying sandy spit of land along this World Heritage site is itself rapidly disappearing in the present. This is the consequence of a changing climate and other man-made problems such as illegal sand-mining and over-development. Today, the southern part of the Langue de Barbarie is an island, and the village of Doune Baba Dieye is under more than a metre of water. The villagers have become climate refugees, forced to live in temporary camps on the mainland. Not only have they lost their homes, but they have also lost significant cultural heritage like the farming and fishing culture tied to this place. The ethical considerations that emerge from climate change impacts on the world’s cultural heritage are varied. However, it seems not as self-evident in the way that research on climate change ethics has been framed around economic interest and direct threats to human life and other species. Even when they mention climate impacts on heritage sites around the world, those of Africans have been side-lined. For instance, the impact of climate change on small island nations like Tuvalu, Kiribati2 have gained much traction in climate change discourse, but we do not get to see stories of Africans whose cherished cultural heritage are affected by climate despoliation. How do we respond to this intractable challenge? This is a question of justice and, to be more precise, climate justice. Many principles and proposals for climate justice have been put forward, but the insufficient attention to the vulnerabilities or loss of cultural heritage values of Africans, which is a critical aspect of their social realities, make these theories less persuasive on a global level. This thesis, then, fills this gap in the literature by suggesting that the failure to take cognizance of the injustice in neglecting cultural heritage values when dealing with the burden of climate change is the effect of three problems. One, the value of culture is less understood in this environmental age. Hence, cultural values are excluded or made to be secondary in consideration of principles of climate justice. Second, the idea of Personhood has been neglected in climate ethics and climate justice discourse. Yet, this idea of Personhood can be an enabler of climate justice in that a realization of the significance of cultural heritage to the wellness of the human persons in Africa, makes it loss morally reprehensible. Third, those whose cultural heritage is significantly affected do not get represented in the debate about sharing the burden of climate change. This dissertation thereby builds upon the general findings of the past about anthropogenic climate change, its causes and consequences. Adopting a discursive normative framework, I also address the significance of cultural heritage in this contemporary environmental age and discuss the global justice implications of cultural heritage loss to climate change. This dissertation further provides a critique of mainstream climate justice theories, especially their marginalization of the cultural dimension of climate change. In this regard, the metaphor - ‘cultural storm’ was deployed to argue that climate justice discourses have neither factored the deep socio-cultural impact of climate change nor do they draw on the cultural understanding of justice in putting forward their theories. Given the nature of the indirect, cumulative, and interconnected invisible losses to cultural heritage from climate change, it seems unlikely that they can be addressed by simple tweaks of the climate justice status quo. This dissertation proposes that the idea of personhood in African philosophy, can be conceived to ensure climate justice live up to its expectations in a world of diverse persons dealing with a complex phenomenon like climate change. It argues that a cultural dimension of climate ethics has implications for how mitigation, adaptation and compensation plans should be furthered for global climate justice. At the foundation of my argument, I suggest that what is needed in climate justice discourse is a commitment to explore new and innovative alternatives that will produce an inclusive global climate treaty that is sensitive to the cultural heritage assets that is destroyed by climate change in Africa. This will require a multi-dimensional framework that allows fundamentally different kinds of values and benefits to be given equal visibility and standing in global climate negotiations. The dissertation proceeds in six chapters. In the first chapter, I discuss how climate change denies, damage and destroys cultural heritage values in Africa and argue that it is unjust to ignore this dimension of climate change impact, particularly on the African continent. In the second chapter, I critically discuss the normative value of cultural heritage in an environmentally sustainable and morally appropriate way for this global age. I argue that what is lost when climate change affects cultural heritage is a significant cultural asset that ought to be seriously considered in climate ethics. The third chapter addresses the global justice implications of the destruction of Africa's cultural heritage by climate change that must be paid attention to. In chapter four, I evaluate the plausibility of some of the mainstream climate justice proposals. I offered a different possible critique of current approaches to climate justice to show how they have furthered cultural injustice. The critique of current climate justice theories that I offer, stems from an uninspiring approach that belies logic permitting the sacrificing of that which is connected to others wellbeing as well as the implicit assumptions and the limitation of the idea of justice that undergird these climate justice theories. I offer, in chapter five, a plausible climate ethics theory that recognizes culturally embedded ideas of justice and empower all stakeholders to build by themselves, lives that are, in the light of these ideas, deemed to be adversely impacted by climate change. This theory advances a socio-cultural perspective to climate change which could provide a nuanced basis for understanding and addressing global climate duties that will be sensitive to the loss of cultural heritage. Specifically, I apply the African conception of personhood, to provide a normative basis for a different but intuitive understanding of the cultural dimension of climate ethics. In the final chapter, I discuss how this theory can be applied to rethink current global responses in the form of mitigation, adaptation and compensation in such a way that it takes seriously the impacts of climate change on Africa’s cultural heritage and values. , Thesis (PhD) -- Faculty of Humanities, Philosophy, 2021
- Full Text:
- Date Issued: 2021-10-29
Evaluating and predicting impacts of Australian redclaw crayfish Cherax quadricarinatus and Louisiana red swamp crayfish Procambarus clarkii invasions
- Madzivanzira, Takudzwa Comfort
- Authors: Madzivanzira, Takudzwa Comfort
- Date: 2021-10-29
- Subjects: Cherax Africa , Procambarus clarkii Africa , Freshwater crabs Africa , Crayfish Zambezi River , Crayfish Food Zambezi River , Aquatic biodiversity Africa , Conservation biology Zambezi River , Fishing Catch effort Africa , Introduced freshwater organisms Africa , Fish populations Africa , Functional response (FR)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191137 , vital:45064 , 10.21504/10962/191137
- Description: Freshwater crayfish have become one of the most widely introduced freshwater taxa globally. Crayfish introductions have not spared the African continent, which, apart from Madagascar, is naturally devoid of native freshwater crayfish. These introductions are of concern because invasive crayfish have generally been shown to cause strong impacts on recipient ecosystems outside Africa. This study therefore set out to compile up-to-date information regarding crayfish introductions in Africa, their pathways and distributions and to improve our understanding of the nature and magnitude of their environmental impacts. A systematic review revealed that nine crayfish species have been introduced into the continent with five of those, Astacus astacus, Cherax quadricarinatus, Faxonius limosus, Procambarus clarkii and Procambarus virginalis, having established naturalised populations in fourteen African countries (Chapter 2). The main driver of these crayfish introductions was to provide socio-economic benefits but there is limited evidence of success. The thesis further documents attempts made to address crayfish knowledge gaps in Africa, including standardisation of C. quadricarinatus sampling gear (Chapter 3), determination of the distribution of C. quadricarinatus in the recently invaded Upper Zambezi Basin (Chapter 4), and predicting ecological and socioeconomic impacts of two crayfish species that are spreading rapidly in Southern Africa, namely, C. quadricarinatus and P. clarkii (Chapters 5 – 8). To standardise C. quadricarinatus sampling methods in Africa, two methods used in Southern Africa were compared and the Promar® collapsible trap baited with dry pellets was recommended as the best approach for C. quadricarinatus abundance studies due to the high catch per unit effort (CPUE), probability of capture and the suitability of dry dog food as a standard bait. This standard approach was used for crayfish surveys in the Zambezi Basin to comprehensively determine the spread and establishment of C. quadricarinatus across the basin. The establishment of C. quadricarinatus in the Barotse Floodplain, Upper Zambezi Floodplains freshwater ecoregion was confirmed. Although the probability of capture and catch per unit effort (CPUE) of C. quadricarinatus in the Barotse floodplain were similar to that of older invasions in the basin (Lake Kariba and Kafue River), morphometric differences among C. quadricarinatus populations sampled from these invaded regions were detected. Although crayfish were not detected in other regions, for example, the Okavango Floodplains ecoregions, C. quadricarinatus have the potential to spread at a downstream and upstream rate of 49 and 12 km·year-1, impacting native biota therein. To evaluate the potential for ecological impacts, the consumer-resource dynamics of C. quadricarinatus and P. clarkii were described in comparison to a native trophic analogue, the freshwater crab of the Potamonautes genus, preying on various native taxa ubiquitous to African aquatic and terrestrial ecosystems. The use of functional response (FR) and consumption experiments in this study showed the potential impacts of the two crayfish species on native resources and on resources that support livelihoods in invaded ecosystems. This in most cases was a result of their high attack parameter, which also resulted in high functional responses ratios (FRRs) compared to native crabs. The crayfish FR, FRRs and consumption rates were mostly enhanced under the high temperature treatments. The FRs and consumption results were then combined with the field biomasses of crayfish and crabs to calculate the relative impact potential (RIP) to successfully predict the degree of impact caused by crayfish species relative to crabs. Crayfish species consistently displayed RIP scores > 1 relative to the native crab irrespective of region, which were higher for the summer than the winter season, suggesting greater impact of the invaders compared to the native species. This study further estimated the socioeconomic losses due to catch spoilage by C. quadricarinatus which are up to 1500 t per year in the invaded Kafue River Basin, which translates to an annual income loss of US$ 2 million. Information provided in this study is vital for conservation management and to compel policymakers to develop appropriate conservation management tools within regulatory frameworks, which could stop or minimise the spread of crayfish species and protect Africa from further losing aquatic biodiversity. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Madzivanzira, Takudzwa Comfort
- Date: 2021-10-29
- Subjects: Cherax Africa , Procambarus clarkii Africa , Freshwater crabs Africa , Crayfish Zambezi River , Crayfish Food Zambezi River , Aquatic biodiversity Africa , Conservation biology Zambezi River , Fishing Catch effort Africa , Introduced freshwater organisms Africa , Fish populations Africa , Functional response (FR)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191137 , vital:45064 , 10.21504/10962/191137
- Description: Freshwater crayfish have become one of the most widely introduced freshwater taxa globally. Crayfish introductions have not spared the African continent, which, apart from Madagascar, is naturally devoid of native freshwater crayfish. These introductions are of concern because invasive crayfish have generally been shown to cause strong impacts on recipient ecosystems outside Africa. This study therefore set out to compile up-to-date information regarding crayfish introductions in Africa, their pathways and distributions and to improve our understanding of the nature and magnitude of their environmental impacts. A systematic review revealed that nine crayfish species have been introduced into the continent with five of those, Astacus astacus, Cherax quadricarinatus, Faxonius limosus, Procambarus clarkii and Procambarus virginalis, having established naturalised populations in fourteen African countries (Chapter 2). The main driver of these crayfish introductions was to provide socio-economic benefits but there is limited evidence of success. The thesis further documents attempts made to address crayfish knowledge gaps in Africa, including standardisation of C. quadricarinatus sampling gear (Chapter 3), determination of the distribution of C. quadricarinatus in the recently invaded Upper Zambezi Basin (Chapter 4), and predicting ecological and socioeconomic impacts of two crayfish species that are spreading rapidly in Southern Africa, namely, C. quadricarinatus and P. clarkii (Chapters 5 – 8). To standardise C. quadricarinatus sampling methods in Africa, two methods used in Southern Africa were compared and the Promar® collapsible trap baited with dry pellets was recommended as the best approach for C. quadricarinatus abundance studies due to the high catch per unit effort (CPUE), probability of capture and the suitability of dry dog food as a standard bait. This standard approach was used for crayfish surveys in the Zambezi Basin to comprehensively determine the spread and establishment of C. quadricarinatus across the basin. The establishment of C. quadricarinatus in the Barotse Floodplain, Upper Zambezi Floodplains freshwater ecoregion was confirmed. Although the probability of capture and catch per unit effort (CPUE) of C. quadricarinatus in the Barotse floodplain were similar to that of older invasions in the basin (Lake Kariba and Kafue River), morphometric differences among C. quadricarinatus populations sampled from these invaded regions were detected. Although crayfish were not detected in other regions, for example, the Okavango Floodplains ecoregions, C. quadricarinatus have the potential to spread at a downstream and upstream rate of 49 and 12 km·year-1, impacting native biota therein. To evaluate the potential for ecological impacts, the consumer-resource dynamics of C. quadricarinatus and P. clarkii were described in comparison to a native trophic analogue, the freshwater crab of the Potamonautes genus, preying on various native taxa ubiquitous to African aquatic and terrestrial ecosystems. The use of functional response (FR) and consumption experiments in this study showed the potential impacts of the two crayfish species on native resources and on resources that support livelihoods in invaded ecosystems. This in most cases was a result of their high attack parameter, which also resulted in high functional responses ratios (FRRs) compared to native crabs. The crayfish FR, FRRs and consumption rates were mostly enhanced under the high temperature treatments. The FRs and consumption results were then combined with the field biomasses of crayfish and crabs to calculate the relative impact potential (RIP) to successfully predict the degree of impact caused by crayfish species relative to crabs. Crayfish species consistently displayed RIP scores > 1 relative to the native crab irrespective of region, which were higher for the summer than the winter season, suggesting greater impact of the invaders compared to the native species. This study further estimated the socioeconomic losses due to catch spoilage by C. quadricarinatus which are up to 1500 t per year in the invaded Kafue River Basin, which translates to an annual income loss of US$ 2 million. Information provided in this study is vital for conservation management and to compel policymakers to develop appropriate conservation management tools within regulatory frameworks, which could stop or minimise the spread of crayfish species and protect Africa from further losing aquatic biodiversity. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-10-29
Exploring indiginising the university’s science curriculum through bottom-up decolonisation: Affordances and hindrances
- Authors: Mutanho, Chrispen
- Date: 2021-10-29
- Subjects: Decolonization South Africa , Ethnoscience South Africa , Ubuntu (Philosophy) , Pedagogical content knowledge , Culturally relevant pedagogy , Science Study and teaching South Africa , Science teachers In-service training South Africa , Transformative learning South Africa , Cultural-historical activity theory (CHAT)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191668 , vital:45146 , 10.21504/10962/191668
- Description: The integration of indigenous knowledge (IK) in the science curriculum is a spreading phenomenon driven by the need to bring about relevancy and equality in science education. In South Africa, for instance, the need to integrate IK in science education is part of the global effort to build a democratic state from the debris of apartheid. Henceforth, the integration of IK is backed up by both the National Constitution of the Republic of South Africa (Act 108 of 1996) and the South African Department of Basic Education’s (2011) National Curriculum Assessment Policy Statement. However, the success of this policy seems to be hindered in part by the fact that the teachers who are the implementers of the curriculum changes seem to lack the relevant pedagogical content knowledge (PCK) to integrate IK in their science teaching repertoires. Such a trend is often blamed on their Eurocentric educational background. Interestingly, very little research has been done to explore ways of supporting teachers to develop the relevant conceptual tools and teaching strategies that will enable them to integrate IK in science teaching. It is against this background that an interventionist case study on how to support the Bachelor of Education Natural Sciences in-service teachers in particular to develop exemplar science lessons that integrate IK as easily accessible resources was conducted. The study is underpinned by three complementary paradigms, namely, the interpretive, the critical, and indigenous research paradigms. While the interpretive paradigm enabled me to understand and interpret descriptive data, the critical paradigm enabled me to take an emancipatory stance and challenge the micro-aggressive elements embedded in conventional research practices; within the indigenous research paradigm, Ubuntu was the relational perspective that informed the researcher-participant relationships in this study. Vygotsky’s sociocultural theory was used as an overarching theoretical framework, in conjunction with the cultural historical activity theory. Additionally, the topic-specific pedagogical content knowledge provided the methodological and analytical tools. Data were gathered through questionnaires, individual face-to-face interviews, focus group interview, participatory observation, and the teachers’ reflections. This study established that if teachers are given back the agency to collaboratively resolve the contradictions that confront them in their workplaces, they can generate their own ideas on how to integrate IK in science vii teaching. The teachers in this study experienced a shift in their agency from a paralysed state of resisting the integration of IK at the beginning of the intervention to an ‘I can do it’ attitude at the end of the intervention. Thus, it could be argued that this study’s major contribution to new knowledge lies in demonstrating possible ways of supporting teachers to integrate IK as easily accessible resources in their science teaching. Additionally, the study also challenged the Eurocentric approach to ethics and offered Ubuntu as a relational perspective that can be used to complement the shortcomings of Eurocentric research paradigms. The study thus recommends that continuing professional development or professional learning communities should afford teachers the opportunity to collaboratively engage with the challenges that they face in their workplaces in order to resolve the contradictions that confront them. , Thesis (PhD) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Mutanho, Chrispen
- Date: 2021-10-29
- Subjects: Decolonization South Africa , Ethnoscience South Africa , Ubuntu (Philosophy) , Pedagogical content knowledge , Culturally relevant pedagogy , Science Study and teaching South Africa , Science teachers In-service training South Africa , Transformative learning South Africa , Cultural-historical activity theory (CHAT)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191668 , vital:45146 , 10.21504/10962/191668
- Description: The integration of indigenous knowledge (IK) in the science curriculum is a spreading phenomenon driven by the need to bring about relevancy and equality in science education. In South Africa, for instance, the need to integrate IK in science education is part of the global effort to build a democratic state from the debris of apartheid. Henceforth, the integration of IK is backed up by both the National Constitution of the Republic of South Africa (Act 108 of 1996) and the South African Department of Basic Education’s (2011) National Curriculum Assessment Policy Statement. However, the success of this policy seems to be hindered in part by the fact that the teachers who are the implementers of the curriculum changes seem to lack the relevant pedagogical content knowledge (PCK) to integrate IK in their science teaching repertoires. Such a trend is often blamed on their Eurocentric educational background. Interestingly, very little research has been done to explore ways of supporting teachers to develop the relevant conceptual tools and teaching strategies that will enable them to integrate IK in science teaching. It is against this background that an interventionist case study on how to support the Bachelor of Education Natural Sciences in-service teachers in particular to develop exemplar science lessons that integrate IK as easily accessible resources was conducted. The study is underpinned by three complementary paradigms, namely, the interpretive, the critical, and indigenous research paradigms. While the interpretive paradigm enabled me to understand and interpret descriptive data, the critical paradigm enabled me to take an emancipatory stance and challenge the micro-aggressive elements embedded in conventional research practices; within the indigenous research paradigm, Ubuntu was the relational perspective that informed the researcher-participant relationships in this study. Vygotsky’s sociocultural theory was used as an overarching theoretical framework, in conjunction with the cultural historical activity theory. Additionally, the topic-specific pedagogical content knowledge provided the methodological and analytical tools. Data were gathered through questionnaires, individual face-to-face interviews, focus group interview, participatory observation, and the teachers’ reflections. This study established that if teachers are given back the agency to collaboratively resolve the contradictions that confront them in their workplaces, they can generate their own ideas on how to integrate IK in science vii teaching. The teachers in this study experienced a shift in their agency from a paralysed state of resisting the integration of IK at the beginning of the intervention to an ‘I can do it’ attitude at the end of the intervention. Thus, it could be argued that this study’s major contribution to new knowledge lies in demonstrating possible ways of supporting teachers to integrate IK as easily accessible resources in their science teaching. Additionally, the study also challenged the Eurocentric approach to ethics and offered Ubuntu as a relational perspective that can be used to complement the shortcomings of Eurocentric research paradigms. The study thus recommends that continuing professional development or professional learning communities should afford teachers the opportunity to collaboratively engage with the challenges that they face in their workplaces in order to resolve the contradictions that confront them. , Thesis (PhD) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
Gaze patterns of expert and amateur sight-readers with particular focus on the cognitive underpinnings of reading key and time signatures
- Authors: Viljoen, Jacobus Frederick
- Date: 2021-10-29
- Subjects: Sight-reading (Music) , Eye tracking , Cognition , Musical notation , Tonality , Musical meter and rhythm
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/190908 , vital:45040 , 10.21504/10962/190908
- Description: Over the last decade, eye-tracking technology has provided researchers with specific tools to study the process of reading (language and music) empirically. Most of these studies have focused on the “Eye-Hand Span” phenomenon (the ability to read ahead of the point of playing). However, little research investigates the cognitive implications of specific aspects of musical notation when performed in real time. This research aimed to observe the fixations patterns of sight-readers in order to investigate the cognitive underpinnings of key and time signatures in music scores. This research project is a quantitative study using a quasi-experimental research design. Tobii eye-tracking equipment and software were used to record the eye movements of 11 expert and 7 amateur keyboard sight-readers. Two key aspects of music notation, key and time signatures, were selected as the main focus of the study. To investigate these aspects, eighteen research participants were provided with seventeen sight-reading examples for one hand (low complexity) and two hands (high complexity) composed specifically by the researcher. Several examples contained one or more unexpected aspects (accidentals or changes of time signature) to test their effect on fixation count and duration. Two variables (fixation count and fixation duration) were utilised to analyze fixation patterns on the selected aspects of the scores. Three main results emerged from the data analysis: 1) Expert sight-readers performed with much greater accuracy than experts in both tests; 2) Expert sight-readers exhibited a higher fixation count on entire scores in complex examples; 3) Both expert and amateur sight-readers fixate more and for longer on certain notational aspects such as key and time signatures than other notational aspects such as deviations or individual notes. This selection of focused attention suggests that both expert and amateur sight-readers cognitively process music scores in a hierarchical order. In conclusion, key and time signatures appear to require more and longer fixations by both groups of readers than other aspects of the score. This supports previous research which suggests that sound musical knowledge may play a positive role in performers’ sight-reading skills, thereby contributing to more successful sight-reading performances. , Thesis (PhD) -- Faculty of Humanities, Music and Musicology, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Viljoen, Jacobus Frederick
- Date: 2021-10-29
- Subjects: Sight-reading (Music) , Eye tracking , Cognition , Musical notation , Tonality , Musical meter and rhythm
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/190908 , vital:45040 , 10.21504/10962/190908
- Description: Over the last decade, eye-tracking technology has provided researchers with specific tools to study the process of reading (language and music) empirically. Most of these studies have focused on the “Eye-Hand Span” phenomenon (the ability to read ahead of the point of playing). However, little research investigates the cognitive implications of specific aspects of musical notation when performed in real time. This research aimed to observe the fixations patterns of sight-readers in order to investigate the cognitive underpinnings of key and time signatures in music scores. This research project is a quantitative study using a quasi-experimental research design. Tobii eye-tracking equipment and software were used to record the eye movements of 11 expert and 7 amateur keyboard sight-readers. Two key aspects of music notation, key and time signatures, were selected as the main focus of the study. To investigate these aspects, eighteen research participants were provided with seventeen sight-reading examples for one hand (low complexity) and two hands (high complexity) composed specifically by the researcher. Several examples contained one or more unexpected aspects (accidentals or changes of time signature) to test their effect on fixation count and duration. Two variables (fixation count and fixation duration) were utilised to analyze fixation patterns on the selected aspects of the scores. Three main results emerged from the data analysis: 1) Expert sight-readers performed with much greater accuracy than experts in both tests; 2) Expert sight-readers exhibited a higher fixation count on entire scores in complex examples; 3) Both expert and amateur sight-readers fixate more and for longer on certain notational aspects such as key and time signatures than other notational aspects such as deviations or individual notes. This selection of focused attention suggests that both expert and amateur sight-readers cognitively process music scores in a hierarchical order. In conclusion, key and time signatures appear to require more and longer fixations by both groups of readers than other aspects of the score. This supports previous research which suggests that sound musical knowledge may play a positive role in performers’ sight-reading skills, thereby contributing to more successful sight-reading performances. , Thesis (PhD) -- Faculty of Humanities, Music and Musicology, 2021
- Full Text:
- Date Issued: 2021-10-29
Human capital in the context of high levels of inequality in South Africa
- Authors: Friderichs, Tamaryn Jean
- Date: 2021-10-29
- Subjects: Human capital South Africa , Income distribution South Africa , Labor market South Africa , Latent variables , Confirmatory factor analysis , Education Economic aspects South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192672 , vital:45248 , 10.21504/10962/192672
- Description: Piketty’s (2014) book titled “Capital in the Twenty-First Century” sparked widespread interest in global inequality, the distinction between wealth and income inequality and the economic, social and political processes accounting for changes in economic inequality over time. Piketty’s (2014) study controversially stated that widening economic inequality is the normal state of affairs in capitalist societies. The return from capital/wealth (terms used interchangeably) will almost always outpace the returns from labour. In contrast with Piketty’s (2014) thesis that the returns on non-human capital drive growing income inequality, economists such as Leibbrandt et al. (2012), Van der Berg (2014) and Hundenborn et al. (2016) have found that the labour market and human capital (HC) are the primary sources of income inequality. The research problem for this study stems from these contrasting views. , Thesis (PhD) -- Faculty of Commerce, Economics and Economic History, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Friderichs, Tamaryn Jean
- Date: 2021-10-29
- Subjects: Human capital South Africa , Income distribution South Africa , Labor market South Africa , Latent variables , Confirmatory factor analysis , Education Economic aspects South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192672 , vital:45248 , 10.21504/10962/192672
- Description: Piketty’s (2014) book titled “Capital in the Twenty-First Century” sparked widespread interest in global inequality, the distinction between wealth and income inequality and the economic, social and political processes accounting for changes in economic inequality over time. Piketty’s (2014) study controversially stated that widening economic inequality is the normal state of affairs in capitalist societies. The return from capital/wealth (terms used interchangeably) will almost always outpace the returns from labour. In contrast with Piketty’s (2014) thesis that the returns on non-human capital drive growing income inequality, economists such as Leibbrandt et al. (2012), Van der Berg (2014) and Hundenborn et al. (2016) have found that the labour market and human capital (HC) are the primary sources of income inequality. The research problem for this study stems from these contrasting views. , Thesis (PhD) -- Faculty of Commerce, Economics and Economic History, 2021
- Full Text:
- Date Issued: 2021-10-29
Integration of dual metallophthalocyanine catalysis and green energy for sustainable oxidative removal of endocrine disrupting compounds
- Authors: Kruid, Jan
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192820 , vital:45267
- Description: Thesis (PhD) -- Faculty of Science, Biotechnology Innovation Centre, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Kruid, Jan
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192820 , vital:45267
- Description: Thesis (PhD) -- Faculty of Science, Biotechnology Innovation Centre, 2021
- Full Text:
- Date Issued: 2021-10-29
Integrative systematic structuring of the widespread psammophiid snakes (Psammophiidae): a multi-evidence species delineation approach
- Authors: Keates, Chad
- Date: 2021-10-29
- Subjects: Psammophis South Africa , Herpetology , Herpetology Africa , Molecular biology , Psammophis Classification , Psammophis Genetics , Psammophis Morphology , Psammophis Phylogeny , Morphology Mathematics , Psammophylax
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/295077 , vital:57288 , DOI 10.21504/10962/295079
- Description: Species form the foundations upon which we build our understanding of the natural world. Although a focus of much scientific attention, our understanding of species is stunted by the intrinsic ‘fuzziness’ of boundaries within nature. Due to the complexity of the evolutionary process, coupled with an ever-changing abiotic landscape, species are hard to delineate, even at the best of times. Whilst various species concepts and sophisticated delimitation methods have helped scientists tease apart species, many species complexes persist. This is because taxonomy is a discrete ordering system imposed upon the continuous and intercalated structure of life. To improve our understanding of a wide-ranging family of snakes, I investigated the taxonomy and evolutionary structuring within Psammophiidae using both molecular and morphological approaches, employing phylogenetic, phylogeographic, and morphometric analyses on the group. The systematic complexity of the family (as evidenced by past research) coupled with the group’s widespread distribution and ecological importance, made the taxon an ideal candidate for a broad-sweeping multi-level systematic analysis using multiple species delimitation methods. Additionally, in this thesis I attempted to build on the ground-breaking work of Christopher Kelly by addressing several knowledge gaps identified within the family, and in so doing, produce the most thorough evolutionary and taxonomic study of Psammophiidae possible. Given the taxonomic uncertainty associated with the family, Chapter Two used a representative sampling from every available species (near complete taxon sampling approach) in the family. The chapter used both standard and time-calibrated phylogenetic modelling and distance/threshold-based species delimitation, to elucidate the finer-level structuring within the family. Geometric morphometrics was used to determine whether there were diagnosable differences in head structure between the different genera. The final phylogenetic tree incorporated 320 samples, representing the most comprehensive phylogenetic reconstruction of the family to date. By using a near-complete taxon sampling approach, I was able to resolve previously unsupported relationships within the family whilst also identifying several novel instances of an under- and over-appreciation of species diversity within the family. Geometric morphometrics also identified clear distinctions between genera based on head shape (head width and ‘beakedness’). This chapter showcased the importance of complete taxon sampling and robust methodology for species delimitation and the deleterious effect of species concepts when implemented in isolation. In Chapter Three, I narrowed the scope of the study to focus on the genus level. Psammophylax (Fitzinger 1843) is an abundant, yet poorly studied genus of grass snakes, endemic to Africa. The generalist nature of the genus and wide-spanning distributions of the constituent species has given rise to several subspecies and a poor understanding of the taxonomic structuring within the genus. The overlapping distributions (sympatry) of many of Psammophylax species, coupled with the potential for cryptic speciation via mechanisms such as convergent evolution, made the group the ideal candidate for a broad-sweeping systematic study (as evidenced in Chapter Two). By applying the suite of analyses used in Chapter Two to the generic level, we aimed to determine the effectiveness of a multi-evidence species delineation approach when tackling systematic problems at lower taxonomic levels. A genetic phylogeny of six of the seven species was estimated using multiple phylogenetic and distance/ threshold-based species delimitation methods. To support the molecular analyses, we conducted morphological analyses on the body (traditional morphology) and head (geometric morphometrics) separately. Phylogenetic analyses recovered a similar topology to past studies, but with better resolution and node support. I found substantial genetic structuring within the genus, supported by significantly different head shapes between Ps. a. acutus and other Psammophylax species. Psammophylax a. acutus was recovered as sister to its congeners, and sequence divergence values and morphometrics supported its recognition as a new genus. Increased sampling in East Africa (Tanzania, Kenya, and Ethiopia) revealed that Psammophylax multisquamis is polyphyletic, necessitating the description of a new, morphologically cryptic, species from northern Tanzania. The distribution of Ps. multisquamis sensu stricto is likely restricted to Kenya and Ethiopia. Within this chapter, taxon-specific phylogenetic analyses yielded stronger intrageneric support as compared to Chapter Two, allowing for more defensible conclusions about taxonomical amendments. Geometric morphometrics proved similarly useful (as compared to Chapter Two) in teasing apart genera within the family but lacked the robustness to delineate species within Psammophylax with confidence, highlighting the apparent convergence of form within the genus. In Chapter Four, I investigated the evolutionary structuring within the Southern African endemic Psammophylax rhombeatus. The structural and environmental heterogeneity within the region has given rise to many morphological forms distributed throughout the country, with previous studies neglecting the associated molecular significance of these forms. Irrespective of their small sample sizes, both Chapter Two and Three identified substantial phylogenetic structuring within the species, making Ps. rhombeatus the ideal candidate for a multi-faceted systematic review, using a combination of phylogenetics, geometric morphometrics and, for the first time in this species, phylogeographic analyses. By investigating a single species, in detail, I was able to assess the effectiveness of the methodologies implemented in previous chapters on systematic sorting using the multi-evidence species delineation approach. Phylogenetic and haplotype analysis retrieved four well-supported clades: southeast South Africa (SESA), southwest South Africa (SWSA), north-eastern South Africa (NESA) and western South Africa (WSA). Although not variable enough to warrant taxonomic re-evaluation, the clades represented important genetic hotspots, with relatively high intraspecific genetic divergence values separating them, irrespective of the small geographic distances separating populations. This is likely a product of the taxon’s habitat-generalist lifestyle, enabling them to bypass vicariant barriers that might otherwise cause speciation in less versatile species. The clades are also geographically distinct, with little overlap, indicating previous vicariance, a finding that is supported by the split of Ps. rhombeatus from Ps. ocellatus in the mid-Pliocene, followed by the diversification of Ps. rhombeatus into four clades throughout the Pleistocene. The genetic structuring observed in Ps. rhombeatus may be a product of population expansion following ancient refugial isolation (potentially Last Glacial Maximum [LGM]). The molecular distinctiveness of the clades was not replicated in the morphological component of this chapter, with neither dorsal nor lateral geometric morphometric analyses of head shape showing any discernible distinctiveness based on geography. Whilst head shape has not been shown to be an effective delineator of evolutionary units at the species level (within this taxon), body colour, scalation, and snout-vent length has been linked to morphotypes within the species based on the work of Broadley (1966). These morphological groupings are loosely attributable to the molecular clades identified in the phylogenetic analyses, highlighting the complex interplay of genetic and morphological characteristics in the process of speciation, and their representation in systematic accounts. This thesis represents the most thorough evolutionary and systematic study of the family currently possible. In addition to identifying and describing both a new genus and species, this thesis also highlighted several instances of an over- and under-appreciation of species diversity within Psammophiidae. By applying a multi-evidence species delineation approach to this thesis, I show the intricacy of the evolutionary process (at various taxonomic levels) and showcase the ease to which species boundaries can be confounded when species concepts are implemented in isolation. These findings also highlighted the importance of sample size, sample range, species delimitation method on the outcome of taxonomic analyses, and their interpretation. Lastly, this thesis addressed the knowledge gaps left by Christopher Kelly’s PhD work and investigated the findings of recent papers that attempted to do the same. Whilst this study answers the questions of old, the taxon-intensive focus revealed several new knowledge gaps within the family, highlighting how much we know about snake systematics, and furthermore, how much we still need to learn about evolutionary structuring. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Keates, Chad
- Date: 2021-10-29
- Subjects: Psammophis South Africa , Herpetology , Herpetology Africa , Molecular biology , Psammophis Classification , Psammophis Genetics , Psammophis Morphology , Psammophis Phylogeny , Morphology Mathematics , Psammophylax
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/295077 , vital:57288 , DOI 10.21504/10962/295079
- Description: Species form the foundations upon which we build our understanding of the natural world. Although a focus of much scientific attention, our understanding of species is stunted by the intrinsic ‘fuzziness’ of boundaries within nature. Due to the complexity of the evolutionary process, coupled with an ever-changing abiotic landscape, species are hard to delineate, even at the best of times. Whilst various species concepts and sophisticated delimitation methods have helped scientists tease apart species, many species complexes persist. This is because taxonomy is a discrete ordering system imposed upon the continuous and intercalated structure of life. To improve our understanding of a wide-ranging family of snakes, I investigated the taxonomy and evolutionary structuring within Psammophiidae using both molecular and morphological approaches, employing phylogenetic, phylogeographic, and morphometric analyses on the group. The systematic complexity of the family (as evidenced by past research) coupled with the group’s widespread distribution and ecological importance, made the taxon an ideal candidate for a broad-sweeping multi-level systematic analysis using multiple species delimitation methods. Additionally, in this thesis I attempted to build on the ground-breaking work of Christopher Kelly by addressing several knowledge gaps identified within the family, and in so doing, produce the most thorough evolutionary and taxonomic study of Psammophiidae possible. Given the taxonomic uncertainty associated with the family, Chapter Two used a representative sampling from every available species (near complete taxon sampling approach) in the family. The chapter used both standard and time-calibrated phylogenetic modelling and distance/threshold-based species delimitation, to elucidate the finer-level structuring within the family. Geometric morphometrics was used to determine whether there were diagnosable differences in head structure between the different genera. The final phylogenetic tree incorporated 320 samples, representing the most comprehensive phylogenetic reconstruction of the family to date. By using a near-complete taxon sampling approach, I was able to resolve previously unsupported relationships within the family whilst also identifying several novel instances of an under- and over-appreciation of species diversity within the family. Geometric morphometrics also identified clear distinctions between genera based on head shape (head width and ‘beakedness’). This chapter showcased the importance of complete taxon sampling and robust methodology for species delimitation and the deleterious effect of species concepts when implemented in isolation. In Chapter Three, I narrowed the scope of the study to focus on the genus level. Psammophylax (Fitzinger 1843) is an abundant, yet poorly studied genus of grass snakes, endemic to Africa. The generalist nature of the genus and wide-spanning distributions of the constituent species has given rise to several subspecies and a poor understanding of the taxonomic structuring within the genus. The overlapping distributions (sympatry) of many of Psammophylax species, coupled with the potential for cryptic speciation via mechanisms such as convergent evolution, made the group the ideal candidate for a broad-sweeping systematic study (as evidenced in Chapter Two). By applying the suite of analyses used in Chapter Two to the generic level, we aimed to determine the effectiveness of a multi-evidence species delineation approach when tackling systematic problems at lower taxonomic levels. A genetic phylogeny of six of the seven species was estimated using multiple phylogenetic and distance/ threshold-based species delimitation methods. To support the molecular analyses, we conducted morphological analyses on the body (traditional morphology) and head (geometric morphometrics) separately. Phylogenetic analyses recovered a similar topology to past studies, but with better resolution and node support. I found substantial genetic structuring within the genus, supported by significantly different head shapes between Ps. a. acutus and other Psammophylax species. Psammophylax a. acutus was recovered as sister to its congeners, and sequence divergence values and morphometrics supported its recognition as a new genus. Increased sampling in East Africa (Tanzania, Kenya, and Ethiopia) revealed that Psammophylax multisquamis is polyphyletic, necessitating the description of a new, morphologically cryptic, species from northern Tanzania. The distribution of Ps. multisquamis sensu stricto is likely restricted to Kenya and Ethiopia. Within this chapter, taxon-specific phylogenetic analyses yielded stronger intrageneric support as compared to Chapter Two, allowing for more defensible conclusions about taxonomical amendments. Geometric morphometrics proved similarly useful (as compared to Chapter Two) in teasing apart genera within the family but lacked the robustness to delineate species within Psammophylax with confidence, highlighting the apparent convergence of form within the genus. In Chapter Four, I investigated the evolutionary structuring within the Southern African endemic Psammophylax rhombeatus. The structural and environmental heterogeneity within the region has given rise to many morphological forms distributed throughout the country, with previous studies neglecting the associated molecular significance of these forms. Irrespective of their small sample sizes, both Chapter Two and Three identified substantial phylogenetic structuring within the species, making Ps. rhombeatus the ideal candidate for a multi-faceted systematic review, using a combination of phylogenetics, geometric morphometrics and, for the first time in this species, phylogeographic analyses. By investigating a single species, in detail, I was able to assess the effectiveness of the methodologies implemented in previous chapters on systematic sorting using the multi-evidence species delineation approach. Phylogenetic and haplotype analysis retrieved four well-supported clades: southeast South Africa (SESA), southwest South Africa (SWSA), north-eastern South Africa (NESA) and western South Africa (WSA). Although not variable enough to warrant taxonomic re-evaluation, the clades represented important genetic hotspots, with relatively high intraspecific genetic divergence values separating them, irrespective of the small geographic distances separating populations. This is likely a product of the taxon’s habitat-generalist lifestyle, enabling them to bypass vicariant barriers that might otherwise cause speciation in less versatile species. The clades are also geographically distinct, with little overlap, indicating previous vicariance, a finding that is supported by the split of Ps. rhombeatus from Ps. ocellatus in the mid-Pliocene, followed by the diversification of Ps. rhombeatus into four clades throughout the Pleistocene. The genetic structuring observed in Ps. rhombeatus may be a product of population expansion following ancient refugial isolation (potentially Last Glacial Maximum [LGM]). The molecular distinctiveness of the clades was not replicated in the morphological component of this chapter, with neither dorsal nor lateral geometric morphometric analyses of head shape showing any discernible distinctiveness based on geography. Whilst head shape has not been shown to be an effective delineator of evolutionary units at the species level (within this taxon), body colour, scalation, and snout-vent length has been linked to morphotypes within the species based on the work of Broadley (1966). These morphological groupings are loosely attributable to the molecular clades identified in the phylogenetic analyses, highlighting the complex interplay of genetic and morphological characteristics in the process of speciation, and their representation in systematic accounts. This thesis represents the most thorough evolutionary and systematic study of the family currently possible. In addition to identifying and describing both a new genus and species, this thesis also highlighted several instances of an over- and under-appreciation of species diversity within Psammophiidae. By applying a multi-evidence species delineation approach to this thesis, I show the intricacy of the evolutionary process (at various taxonomic levels) and showcase the ease to which species boundaries can be confounded when species concepts are implemented in isolation. These findings also highlighted the importance of sample size, sample range, species delimitation method on the outcome of taxonomic analyses, and their interpretation. Lastly, this thesis addressed the knowledge gaps left by Christopher Kelly’s PhD work and investigated the findings of recent papers that attempted to do the same. Whilst this study answers the questions of old, the taxon-intensive focus revealed several new knowledge gaps within the family, highlighting how much we know about snake systematics, and furthermore, how much we still need to learn about evolutionary structuring. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2021
- Full Text:
- Date Issued: 2021-10-29
Legal ethics and the lawyer-client relationship in South Africa: A proposal for reform using local values
- Authors: Kruuse, Helen Julia
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192765 , vital:45262
- Description: Thesis (PhD) -- Faculty of Law, Law, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Kruuse, Helen Julia
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192765 , vital:45262
- Description: Thesis (PhD) -- Faculty of Law, Law, 2021
- Full Text:
- Date Issued: 2021-10-29
Mediating and examining expansive learning in the context of multidimensional complexities affecting household food security activity systems in Nyanyadzi Irrigation Scheme in the Manicaland Province of Zimbabwe
- Authors: Mukwambo, Robson
- Date: 2021-10-29
- Subjects: Active learning Zimbabwe Chimanimani District , Food security Zimbabwe Chimanimani District , Sustainable agriculture Zimbabwe Chimanimani District , Irrigation farming Zimbabwe Chimanimani District , Qualitative research , Cultural-historical activity theory (CHAT) , Nyanyadzi Irrigation Scheme
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192712 , vital:45253 , 10.21504/10962/192712
- Description: The study sought to mediate and examine expansive learning in the context of multidimensional complexities affecting household food security activity systems in Nyanyadzi Irrigation Scheme in Ward 8 of Chimanimani District in the Manicaland province of Zimbabwe. Therefore, the main foci of the study were to investigate how multidimensional complexities have come to be the way they are (historicizing) and how they enable or constrain learning of household food production. The study utilized Cultural Historical Activity Theory and the Expansive Learning Cycle (Engeström & Sannino, 2010) to examine and mediate collective learning in response to the multidimensional complexities and also to contribute to transforming the farmers’ activity systems towards more sustainable practices to ensure household food security. The study used a qualitative research approach, utilizing an insider formative intervention approach in a case study design in which Nyanyadzi irrigation scheme was the case study. I have adopted the insider formative interventionist role as a 3rd generation farmer, born and bred in Nyanyadzi area, and my family has been involved in the Nyanyadzi irrigation scheme for three generations. I see this as synergistic with the need for deep cultural understanding in CHAT research. However, this role also provided challenges for me to maintain a rigorous approach to the research in which I also reflexively review my own role and influence in the research process. Following CHAT expansive learning methodological guidance, data was generated through fifteen (15) face to face interviews with three generations of farmers in the scheme (historical ethnographic data); four focus group discussions (contemporary ethnographic data) and eight (8) sessions in a three (3) day change laboratory workshop (expansive learning data). Double stimulation and ‘mirror’ data was used to surface and prioritise responses to contradictions in the Change Laboratory Workshops (CLW), which is a methodology developed in and for CHAT research (ibid). The data was analysed using both inductive and abductive approaches and were conducted in a three-phased process focusing firstly on the history of the object, followed by current perspectives on the object of activity and lastly on transformations emerging in the object of activity via the expansive learning process. Cultural Historical Activity Theoretical tools informed activity system analysis and analysis of the history of the object and emerging contradictions; and the expansive learning cycle (ELP) process framework associated with and emergent from CHAT was used to analyse the emergence of transformative agency and expansion of the object. Four levels of contradictions were used to describe and explain the emergent contradictions namely, primary, secondary, tertiary and quaternary contradictions and are presented in this sequence as catalytic opportunities for expansive learning as proposed in CHAT. In addition, the four types of discursive manifestations of contradictions namely, dilemma, conflict, critical conflict and double bind were used to describe and explain the manifestations of contradictions in this study and their role in catalysing transformative agency. The concept of linguistic cues for discursive manifestations of contradictions was adopted and employed in the preliminary data analysis phase. In addition, the transformative agency expressions and zone of proximal development (ZPD) concept was applied in and to the CLW data to examine the learning pathways and to co-develop and expand farmers’ and other stakeholders’ transformative agency and ZPD respectively. I found myself as formative insider researcher having to take on a strong role as co-engaged researcher / participant in the irrigation scheme expansive learning process. The study concluded that the farmers’ activity system is the central activity system and it interacts with other activity systems on a partially shared object “improved crop production and marketing under irrigation scheme”. Through interactions with other neighbouring activity systems, the farmers have faced multidimensional complexities that constrain their ability to fully realise their object. These multidimensional complexities manifest in three critical contradictions as a critical conflict in leadership and management crisis; a dilemma and double bind in a lack of farmer education and training; and lastly, a dilemma and double bind in poor crop marketing. These multidimensional complexities have a historical account and they have evolved in complexity over time and I argue in the thesis that, a careful cultural-historicity of the object of activity and mediation of the situated learning can help to collectively come up with solutions to these multidimensional complexities. The study further concluded that despite these multidimensional complexities in the scheme, learning has been taking place and such learning was sometimes mediated through demonstrations as “learning by doing,” “seeing is believing” and the “winners and losers” concept. Furthermore, through the CLW process the farmers and other stakeholders’ cognitive horizons were expanded by the mirror data and double stimulation processes, and the expansive learning process developed their individual and collective transformative agency pathways and expanded their collective zone of proximal development. In this study I argue that there has been little said about collective learning in irrigation schemes and given the dearth of detail on such learning, it seems that this learning is either going unnoticed or is ignored. Hence, I further argued that the multidimensional complexities in irrigation schemes are both a stimulant for learning and provide a space (object) for collective learning, as was also shown by Baloi (2016). The study also shows that the collective learning potential in these irrigation schemes can be pro-actively mediated via expansive learning formative interventions in support of improved crop production and marketing for produce developed under irrigation in irrigation schemes such as the Nyanyadzi Irrigation scheme. Lastly, being an insider formative interventionist researcher in this study, with intergenerational engagement and perspective on the history of the object and integrational engagement with the transforming object, I became part of the intergenerational transformation of the irrigation scheme’s object. The intergenerational co-construction of the history of the object, coupled with the insider formative interventionist researcher approach opened up and allowed me as a current generation agent or actor to develop an in-depth understanding of the multidimensional nature and historicity of the object. This was crucial for opening up the transformative agency pathways. It also produced a responsibility for me as an insider formative interventionist researcher to carry the summative findings of the study back into the social context to widen the engagement and mediation of the transformation needed in the community. Overall not only does the study offer an intergenerational perspective on multidimensional complexities of the object and how this can generatively be mobilised via expansive learning into emerging transformative learning agency pathways, but it also offers a new vantage point on the role of the insider formative interventionist researcher. Through this, the study offers insight into how we as third generation members of the community can be brought closer to our communities through the application of our skills, thereby also offering a new type of engaged and rigorously framed and executed research with roots in our communities. As shown in this study, not only does this expand the knowledge and experience of those we engage with, but it also expands our own knowledge and expertise in order to be more able to contribute to both the challenges of our own communities but also that of other communities and situations similar to ours, and beyond these bounded contexts. The study’s contribution is both practical, but also methodological from this vantage point, especially in an African context where there is much critique of ‘outsider research’, yet little pro-active articulation of what insider (in this case, formative intervention) research may look like. , Thesis (PhD) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Mukwambo, Robson
- Date: 2021-10-29
- Subjects: Active learning Zimbabwe Chimanimani District , Food security Zimbabwe Chimanimani District , Sustainable agriculture Zimbabwe Chimanimani District , Irrigation farming Zimbabwe Chimanimani District , Qualitative research , Cultural-historical activity theory (CHAT) , Nyanyadzi Irrigation Scheme
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192712 , vital:45253 , 10.21504/10962/192712
- Description: The study sought to mediate and examine expansive learning in the context of multidimensional complexities affecting household food security activity systems in Nyanyadzi Irrigation Scheme in Ward 8 of Chimanimani District in the Manicaland province of Zimbabwe. Therefore, the main foci of the study were to investigate how multidimensional complexities have come to be the way they are (historicizing) and how they enable or constrain learning of household food production. The study utilized Cultural Historical Activity Theory and the Expansive Learning Cycle (Engeström & Sannino, 2010) to examine and mediate collective learning in response to the multidimensional complexities and also to contribute to transforming the farmers’ activity systems towards more sustainable practices to ensure household food security. The study used a qualitative research approach, utilizing an insider formative intervention approach in a case study design in which Nyanyadzi irrigation scheme was the case study. I have adopted the insider formative interventionist role as a 3rd generation farmer, born and bred in Nyanyadzi area, and my family has been involved in the Nyanyadzi irrigation scheme for three generations. I see this as synergistic with the need for deep cultural understanding in CHAT research. However, this role also provided challenges for me to maintain a rigorous approach to the research in which I also reflexively review my own role and influence in the research process. Following CHAT expansive learning methodological guidance, data was generated through fifteen (15) face to face interviews with three generations of farmers in the scheme (historical ethnographic data); four focus group discussions (contemporary ethnographic data) and eight (8) sessions in a three (3) day change laboratory workshop (expansive learning data). Double stimulation and ‘mirror’ data was used to surface and prioritise responses to contradictions in the Change Laboratory Workshops (CLW), which is a methodology developed in and for CHAT research (ibid). The data was analysed using both inductive and abductive approaches and were conducted in a three-phased process focusing firstly on the history of the object, followed by current perspectives on the object of activity and lastly on transformations emerging in the object of activity via the expansive learning process. Cultural Historical Activity Theoretical tools informed activity system analysis and analysis of the history of the object and emerging contradictions; and the expansive learning cycle (ELP) process framework associated with and emergent from CHAT was used to analyse the emergence of transformative agency and expansion of the object. Four levels of contradictions were used to describe and explain the emergent contradictions namely, primary, secondary, tertiary and quaternary contradictions and are presented in this sequence as catalytic opportunities for expansive learning as proposed in CHAT. In addition, the four types of discursive manifestations of contradictions namely, dilemma, conflict, critical conflict and double bind were used to describe and explain the manifestations of contradictions in this study and their role in catalysing transformative agency. The concept of linguistic cues for discursive manifestations of contradictions was adopted and employed in the preliminary data analysis phase. In addition, the transformative agency expressions and zone of proximal development (ZPD) concept was applied in and to the CLW data to examine the learning pathways and to co-develop and expand farmers’ and other stakeholders’ transformative agency and ZPD respectively. I found myself as formative insider researcher having to take on a strong role as co-engaged researcher / participant in the irrigation scheme expansive learning process. The study concluded that the farmers’ activity system is the central activity system and it interacts with other activity systems on a partially shared object “improved crop production and marketing under irrigation scheme”. Through interactions with other neighbouring activity systems, the farmers have faced multidimensional complexities that constrain their ability to fully realise their object. These multidimensional complexities manifest in three critical contradictions as a critical conflict in leadership and management crisis; a dilemma and double bind in a lack of farmer education and training; and lastly, a dilemma and double bind in poor crop marketing. These multidimensional complexities have a historical account and they have evolved in complexity over time and I argue in the thesis that, a careful cultural-historicity of the object of activity and mediation of the situated learning can help to collectively come up with solutions to these multidimensional complexities. The study further concluded that despite these multidimensional complexities in the scheme, learning has been taking place and such learning was sometimes mediated through demonstrations as “learning by doing,” “seeing is believing” and the “winners and losers” concept. Furthermore, through the CLW process the farmers and other stakeholders’ cognitive horizons were expanded by the mirror data and double stimulation processes, and the expansive learning process developed their individual and collective transformative agency pathways and expanded their collective zone of proximal development. In this study I argue that there has been little said about collective learning in irrigation schemes and given the dearth of detail on such learning, it seems that this learning is either going unnoticed or is ignored. Hence, I further argued that the multidimensional complexities in irrigation schemes are both a stimulant for learning and provide a space (object) for collective learning, as was also shown by Baloi (2016). The study also shows that the collective learning potential in these irrigation schemes can be pro-actively mediated via expansive learning formative interventions in support of improved crop production and marketing for produce developed under irrigation in irrigation schemes such as the Nyanyadzi Irrigation scheme. Lastly, being an insider formative interventionist researcher in this study, with intergenerational engagement and perspective on the history of the object and integrational engagement with the transforming object, I became part of the intergenerational transformation of the irrigation scheme’s object. The intergenerational co-construction of the history of the object, coupled with the insider formative interventionist researcher approach opened up and allowed me as a current generation agent or actor to develop an in-depth understanding of the multidimensional nature and historicity of the object. This was crucial for opening up the transformative agency pathways. It also produced a responsibility for me as an insider formative interventionist researcher to carry the summative findings of the study back into the social context to widen the engagement and mediation of the transformation needed in the community. Overall not only does the study offer an intergenerational perspective on multidimensional complexities of the object and how this can generatively be mobilised via expansive learning into emerging transformative learning agency pathways, but it also offers a new vantage point on the role of the insider formative interventionist researcher. Through this, the study offers insight into how we as third generation members of the community can be brought closer to our communities through the application of our skills, thereby also offering a new type of engaged and rigorously framed and executed research with roots in our communities. As shown in this study, not only does this expand the knowledge and experience of those we engage with, but it also expands our own knowledge and expertise in order to be more able to contribute to both the challenges of our own communities but also that of other communities and situations similar to ours, and beyond these bounded contexts. The study’s contribution is both practical, but also methodological from this vantage point, especially in an African context where there is much critique of ‘outsider research’, yet little pro-active articulation of what insider (in this case, formative intervention) research may look like. , Thesis (PhD) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
Microalgal-bacterial flocs and extracellular polymeric substances for optimum function of integrated algal pond systems
- Authors: Jimoh, Taobat Adekilekun
- Date: 2021-10-29
- Subjects: Flocculation , Extracellular polymeric substances , Water Purification , Sewage Purification Anaerobic treatment , Integrated algae pond systems (IAPS) , Microalgal-bacterial flocs
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191214 , vital:45071 , 10.21504/10962/191214
- Description: Despite the dire state of sanitation infrastructures, water scarcity, and the dwindling reserve of natural resources due to ever-increasing population growth, implementation of a suitable technology that can provide a solution to all these issues continues to be ignored. The integrated algal pond system (IAPS) is a wastewater treatment technology that combines the processes of anaerobic digestion and photosynthetic oxygenation to achieve wastewater treatment and facilitate the recovery of treated water and resources in the form of biogas and microalgal-bacterial biomass. The natural process of bioflocculation through microalgal-bacterial mutualism and production of extracellular polymeric substances (EPS) in high rate algal oxidation ponds (HRAOPs) of an IAPS increases efficiency of wastewater treatment and potentially enhances harvestability and biomass recovery, which could contribute significantly to the successful establishment of a biorefinery. Using a 500 PE pilot-scale IAPS supplied domestic sewage coupled with laboratory experiments, this study investigated the importance and function of in situ EPS production and MaB-floc formation in HRAOP. A metagenomic study revealed the biological components of the biomass or mixed liquor suspended solids (MLSS) produced in HRAOP and showed that the suspended biomass is composed largely of eukaryotes that were dominated by the colonial microalgae Pseudopediastrum sp. and Desmodesmus sp., and a diverse range of prokaryotes including bacteria and cyanobacteria. Dominance, within the bacterial population, by a sulphur-oxidizing bacterium, Thiothrix which comprised up to 80% of the prokaryotes, coincided with a period of poor flocculation and was therefore rationalized to have contributed to bulking and poor biomass settleability. Otherwise, good flocs were formed in the MLSS with settleability up to 95% and, within 1 h. The formation of MaB-flocs appeared to be dependent on EPS concentration of the mixed liquor due to the observed positive correlation between soluble EPS (S-EPS), biomass concentration, and settleability. The contribution and role of MLSS components towards the formation and sustenance of MaB-flocs were further demonstrated in laboratory experiments using pure strains of microalgae, cyanobacteria, and bacteria. Results showed that pure cultures of dominant microalgae in MLSS, Pseudopediastrum sp. and Desmodesmus sp. achieved a rapid 92 and 75% settleability within 3 h. A self-flocculating filamentous cyanobacterium, Leptolyngbya strain ECCN 20BG was isolated, characterized, and shown to achieve 99% settleability within 5 min by forming large tightly aggregated flocs. In further experiments, this strain was found to improve the settleability of MLSS by an average of 20%. Bacterial strains identified as Bacillus strain ECCN 40b, Bacillus strain ECCN 41b, Planococcus strain ECCN 45b, and Exiguobacterium strain ECCN 46b were also observed to produce sticky EPS-like materials in pure cultures that could also contribute to the aggregation of cells in a mixed environment. Given these results, various factors and/or mechanisms that might enhance microbial aggregation and biomass recovery from HRAOP MLSS were identified in this study and include; (1) dominance by larger colonial microalgae prevents disintegration of MaB-flocs and enhances recovery of biomass from MLSS by gravity sedimentation, (2) presence of filamentous cyanobacteria species that can self-flocculate to form an interwoven network of filaments may play an important role in the structural stability and settleability of MaB-flocs in MLSS, and (3) production of EPS to form the matrix or scaffold whereon all microbial components aggregate to develop a microenvironment. Indeed, all forms of EPS, except for that produced by Bacillus strain ECCN 41b, showed bioflocculating property and were able to serve as flocculants for the recovery of Chlorella, an alga known for its poor settleability. A combination of biochemical analyses and FTIR spectroscopy revealed the importance of carbohydrate enrichment of these biopolymers. Carbohydrate concentration in all forms of EPS was between 12 and 41% suggesting that production of these compounds by microbes within the MLSS contributed to MaB-floc formation. EPS extracted from bulk MLSS and EPS produced by Bacillus strains possessed some surface-active properties that were comparable to Triton X-100, indicating potential application in bioremediation and recovery of oil from contaminated soil and water. In particular, EPS generated from Bacillus strain ECCN 41b displayed relatively distinct properties including the quantity produced (> 500 mg/L), increased viscosity, inability to flocculate microalgal cells, a rhamnolipid content of 32%, and a higher surface-activity. Based on these results, Bacillus strain ECCN 41b was rationalized to produce anionic EPS with potential application in metal or oil recovery. In addition to EPS production, the bacteria Planococcus strain ECCN 45b and Exiguobacterium strain ECCN 46b appeared pigmented. Based on partial characterization using UV/Vis spectrophotometry, thin-layer chromatography, FTIR, and NMR, the pigments produced by these two strains appeared to be identical and were tentatively identified as ketocarotenoids. This study successfully demonstrated the importance of EPS production and formation of MaB-flocs in the MLSS from HRAOP of an IAPS treating domestic sewage. It is evident that increased settleability of the biomass does contribute to the reported efficiency of wastewater treatment by IAPS and would reduce both total suspended solids (TSS) and chemical oxygen demand (COD). In addition, demonstration that this biomass contains products of value such as carotenoids and EPS with potential for commercial use strengthens the idea of using IAPS as a platform technology for innovation of the wastewater treatment process to a biorefinery. , Thesis (PhD) -- Faculty of Science, Institute for Environmental Biotechnology, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Jimoh, Taobat Adekilekun
- Date: 2021-10-29
- Subjects: Flocculation , Extracellular polymeric substances , Water Purification , Sewage Purification Anaerobic treatment , Integrated algae pond systems (IAPS) , Microalgal-bacterial flocs
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191214 , vital:45071 , 10.21504/10962/191214
- Description: Despite the dire state of sanitation infrastructures, water scarcity, and the dwindling reserve of natural resources due to ever-increasing population growth, implementation of a suitable technology that can provide a solution to all these issues continues to be ignored. The integrated algal pond system (IAPS) is a wastewater treatment technology that combines the processes of anaerobic digestion and photosynthetic oxygenation to achieve wastewater treatment and facilitate the recovery of treated water and resources in the form of biogas and microalgal-bacterial biomass. The natural process of bioflocculation through microalgal-bacterial mutualism and production of extracellular polymeric substances (EPS) in high rate algal oxidation ponds (HRAOPs) of an IAPS increases efficiency of wastewater treatment and potentially enhances harvestability and biomass recovery, which could contribute significantly to the successful establishment of a biorefinery. Using a 500 PE pilot-scale IAPS supplied domestic sewage coupled with laboratory experiments, this study investigated the importance and function of in situ EPS production and MaB-floc formation in HRAOP. A metagenomic study revealed the biological components of the biomass or mixed liquor suspended solids (MLSS) produced in HRAOP and showed that the suspended biomass is composed largely of eukaryotes that were dominated by the colonial microalgae Pseudopediastrum sp. and Desmodesmus sp., and a diverse range of prokaryotes including bacteria and cyanobacteria. Dominance, within the bacterial population, by a sulphur-oxidizing bacterium, Thiothrix which comprised up to 80% of the prokaryotes, coincided with a period of poor flocculation and was therefore rationalized to have contributed to bulking and poor biomass settleability. Otherwise, good flocs were formed in the MLSS with settleability up to 95% and, within 1 h. The formation of MaB-flocs appeared to be dependent on EPS concentration of the mixed liquor due to the observed positive correlation between soluble EPS (S-EPS), biomass concentration, and settleability. The contribution and role of MLSS components towards the formation and sustenance of MaB-flocs were further demonstrated in laboratory experiments using pure strains of microalgae, cyanobacteria, and bacteria. Results showed that pure cultures of dominant microalgae in MLSS, Pseudopediastrum sp. and Desmodesmus sp. achieved a rapid 92 and 75% settleability within 3 h. A self-flocculating filamentous cyanobacterium, Leptolyngbya strain ECCN 20BG was isolated, characterized, and shown to achieve 99% settleability within 5 min by forming large tightly aggregated flocs. In further experiments, this strain was found to improve the settleability of MLSS by an average of 20%. Bacterial strains identified as Bacillus strain ECCN 40b, Bacillus strain ECCN 41b, Planococcus strain ECCN 45b, and Exiguobacterium strain ECCN 46b were also observed to produce sticky EPS-like materials in pure cultures that could also contribute to the aggregation of cells in a mixed environment. Given these results, various factors and/or mechanisms that might enhance microbial aggregation and biomass recovery from HRAOP MLSS were identified in this study and include; (1) dominance by larger colonial microalgae prevents disintegration of MaB-flocs and enhances recovery of biomass from MLSS by gravity sedimentation, (2) presence of filamentous cyanobacteria species that can self-flocculate to form an interwoven network of filaments may play an important role in the structural stability and settleability of MaB-flocs in MLSS, and (3) production of EPS to form the matrix or scaffold whereon all microbial components aggregate to develop a microenvironment. Indeed, all forms of EPS, except for that produced by Bacillus strain ECCN 41b, showed bioflocculating property and were able to serve as flocculants for the recovery of Chlorella, an alga known for its poor settleability. A combination of biochemical analyses and FTIR spectroscopy revealed the importance of carbohydrate enrichment of these biopolymers. Carbohydrate concentration in all forms of EPS was between 12 and 41% suggesting that production of these compounds by microbes within the MLSS contributed to MaB-floc formation. EPS extracted from bulk MLSS and EPS produced by Bacillus strains possessed some surface-active properties that were comparable to Triton X-100, indicating potential application in bioremediation and recovery of oil from contaminated soil and water. In particular, EPS generated from Bacillus strain ECCN 41b displayed relatively distinct properties including the quantity produced (> 500 mg/L), increased viscosity, inability to flocculate microalgal cells, a rhamnolipid content of 32%, and a higher surface-activity. Based on these results, Bacillus strain ECCN 41b was rationalized to produce anionic EPS with potential application in metal or oil recovery. In addition to EPS production, the bacteria Planococcus strain ECCN 45b and Exiguobacterium strain ECCN 46b appeared pigmented. Based on partial characterization using UV/Vis spectrophotometry, thin-layer chromatography, FTIR, and NMR, the pigments produced by these two strains appeared to be identical and were tentatively identified as ketocarotenoids. This study successfully demonstrated the importance of EPS production and formation of MaB-flocs in the MLSS from HRAOP of an IAPS treating domestic sewage. It is evident that increased settleability of the biomass does contribute to the reported efficiency of wastewater treatment by IAPS and would reduce both total suspended solids (TSS) and chemical oxygen demand (COD). In addition, demonstration that this biomass contains products of value such as carotenoids and EPS with potential for commercial use strengthens the idea of using IAPS as a platform technology for innovation of the wastewater treatment process to a biorefinery. , Thesis (PhD) -- Faculty of Science, Institute for Environmental Biotechnology, 2021
- Full Text:
- Date Issued: 2021-10-29
Mitigating salt accumulation in recycled brewery effluent through the integration of water treatment, agriculture and aquaculture
- Authors: Mabasa, Nyiko Charity
- Date: 2021-10-29
- Subjects: Brewery waste South Africa Eastern Cape , Recycling (Waste, etc.) South Africa Eastern Cape , Water reuse South Africa Eastern Cape , Irrigation South Africa Eastern Cape , Sewage Purification Anaerobic treatment , Constructed wetlands , Aquaculture
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191126 , vital:45063 , 10.21504/10962/191126
- Description: Water scarcity in South Africa, and globally, presents challenges for industries. It is imperative to develop responsible water use, such as recycling and reusing wastewater from food processing industries such as breweries. The Ibhayi Brewery (SAB Ltd) employs a combination of sustainable treatment processes that include anaerobic digestion (AD), primary facultative ponds (PFP), high rate algal ponds (HRAP) and constructed wetlands (CW) to treat brewery effluent on an experimental scale. The constituent concentrations of these experimentally treated effluents are within the ranges prescribed by local regulations to allow for potential downstream use in agriculture and aquaculture. However, the sodium content in this treated effluent, which originates from upstream cleaning agents and pH control at the onsite effluent treatment facility, is a constraint to the downstream use of brewery effluent. This study addresses the salt problem, by investigating the potential of either reducing/eliminating salt addition at source, or developing alternative techniques for downstream agriculture to mitigate the effects of salt accumulation caused by irrigation with brewery effluent. Four salt-tolerant test crops; Swiss chard (Beta vulgaris), saltbush (Atriplex nummularia), Salicornia meyeriana and sorghum (Sorghum bicolor), grew efficiently in brewery effluent irrigated soils but did not stop sodium accumulation in the growth medium. Swiss chard had the best growth with a wet biomass accumulation of 8,173 g m-2, due to the plant’s ability to tolerate saline conditions and continuous cropping. Crop rotation, to limit effects of nutrient depletion in soil, had no significant effect on plant growth suggesting soils were adequately able to provide micro-nutrients in the short-term. Prolonged irrigation with brewery effluent can lead to sodium accumulation in the soil, which was successfully controlled through the addition of soil amendments (gypsum and Trichoderma cultures). These reduced soil sodium from a potentially limiting level of 1,398 mg L-1 to the acceptable levels of 240 mg L-1 and 353 mg L-1 respectively, mainly through leaching. However only Trichoderma improved Swiss chard production to 11,238 g m-2. While crop rotation in this work did not contribute to mitigating the problem of salt accumulation, soil amended with Trichoderma appears to be a potential solution when brewery effluent is reused in agriculture. In an alternative to soil cultivation, CWs were trialled with no significant differences in the sodium concentration of brewery effluent treated along a 15 m lateral flow CW, which could be attributed to evapotranspiration. This was notably accompanied by a desirable 95.21% decrease in ammonia from inlet to outlet resulting in significant improvement in water quality for reuse in aquaculture where ammonia levels are important limiting constraints. While CWs remain a suitable brewery effluent treatment solution, this technology requires additional modelling and optimisation in order to mitigate the problem of salt accumulation in the reuse of treated brewery effluent in agriculture and aquaculture. This research demonstrates the baseline information for such modelling and optimisation. African catfish (Clarias gariepinus) grew in CW treated brewery effluent; however, this growth was moderate at 0.92% bw day-1, whereas Mozambique tilapia (Oreochromis mossambicus) were shown to be unsuited to growth in this system and lost weight with an average specific growth rate (SGR) of -0.98% bw day-1; and both fish species presenting with health related concerns. Hardy fish species such as African catfish can be cultured in brewery effluent, but with risk involved. This was a preliminary study to develop parameters for future dimensional analysis modelling to allow optimisation of the CW, based on nutrient removal rates obtained which will allow for improved downstream aquaculture by reducing or eliminating risks presented in this study. This work has also contributed to a foundation for the development of guidelines that use a risk-based approach for water use in aquaculture. Alternatives to the current in place cleaning agents were considered to mitigate the effects of salt accumulation. Sodium is introduced into the effluent via the use of sodium hydroxide and sodium chlorite for cleaning and disinfection in the brewery, as well as through effluent pH adjustment in the AD plant. The widespread use of outdated legacy cleaning systems and pH adjustment regimes is entrenched in the brewery standard operating procedures (SOP). A cost-benefit analysis (CBA) demonstrated that a change of cleaning and disinfecting regimes to hydrogen peroxide in the brewery, and magnesium hydroxide pH adjustment in the effluent treatment plant addresses the sodium issue upstream in the brewery practically eliminating sodium from the effluent. In addition, a life cycle analysis (LCA) was carried out to assess the environmental impacts associated with the alternative cleaning and pH adjustment scenarios. The LCA showed that electricity consumption during use phase of the chemicals for respective purposes, as well as their production activities were major contributors to the significant environmental impact categories that were assessed. The cleaning scenario employing the use of hydrogen peroxide for both cleaning and disinfection was found to be the most environmentally sustainable. This was attributed to the reduced number of chemicals used compared to the other cleaning scenarios. Dolomitic lime was the pH adjustment alternative with the lowest average environmental impact; but, however, had a higher impact on freshwater eutrophication which is of major concern if the effluent will be reused for irrigation. Magnesium hydroxide was therefore considered to be the better option as a sodium hydroxide alternative for pH adjustment. This mitigates salt accumulation, making treated brewery effluent suitable for reuse in high value downstream agriculture and aquaculture, while employing more environmentally sustainable technologies. Notably, this converts brewery effluent from a financial liability to Ibhayi Brewery, into a product containing water and nutrients that generate income, improve food security, and can create employment in downstream agriculture and aquaculture in a sustainable manner. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Mabasa, Nyiko Charity
- Date: 2021-10-29
- Subjects: Brewery waste South Africa Eastern Cape , Recycling (Waste, etc.) South Africa Eastern Cape , Water reuse South Africa Eastern Cape , Irrigation South Africa Eastern Cape , Sewage Purification Anaerobic treatment , Constructed wetlands , Aquaculture
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191126 , vital:45063 , 10.21504/10962/191126
- Description: Water scarcity in South Africa, and globally, presents challenges for industries. It is imperative to develop responsible water use, such as recycling and reusing wastewater from food processing industries such as breweries. The Ibhayi Brewery (SAB Ltd) employs a combination of sustainable treatment processes that include anaerobic digestion (AD), primary facultative ponds (PFP), high rate algal ponds (HRAP) and constructed wetlands (CW) to treat brewery effluent on an experimental scale. The constituent concentrations of these experimentally treated effluents are within the ranges prescribed by local regulations to allow for potential downstream use in agriculture and aquaculture. However, the sodium content in this treated effluent, which originates from upstream cleaning agents and pH control at the onsite effluent treatment facility, is a constraint to the downstream use of brewery effluent. This study addresses the salt problem, by investigating the potential of either reducing/eliminating salt addition at source, or developing alternative techniques for downstream agriculture to mitigate the effects of salt accumulation caused by irrigation with brewery effluent. Four salt-tolerant test crops; Swiss chard (Beta vulgaris), saltbush (Atriplex nummularia), Salicornia meyeriana and sorghum (Sorghum bicolor), grew efficiently in brewery effluent irrigated soils but did not stop sodium accumulation in the growth medium. Swiss chard had the best growth with a wet biomass accumulation of 8,173 g m-2, due to the plant’s ability to tolerate saline conditions and continuous cropping. Crop rotation, to limit effects of nutrient depletion in soil, had no significant effect on plant growth suggesting soils were adequately able to provide micro-nutrients in the short-term. Prolonged irrigation with brewery effluent can lead to sodium accumulation in the soil, which was successfully controlled through the addition of soil amendments (gypsum and Trichoderma cultures). These reduced soil sodium from a potentially limiting level of 1,398 mg L-1 to the acceptable levels of 240 mg L-1 and 353 mg L-1 respectively, mainly through leaching. However only Trichoderma improved Swiss chard production to 11,238 g m-2. While crop rotation in this work did not contribute to mitigating the problem of salt accumulation, soil amended with Trichoderma appears to be a potential solution when brewery effluent is reused in agriculture. In an alternative to soil cultivation, CWs were trialled with no significant differences in the sodium concentration of brewery effluent treated along a 15 m lateral flow CW, which could be attributed to evapotranspiration. This was notably accompanied by a desirable 95.21% decrease in ammonia from inlet to outlet resulting in significant improvement in water quality for reuse in aquaculture where ammonia levels are important limiting constraints. While CWs remain a suitable brewery effluent treatment solution, this technology requires additional modelling and optimisation in order to mitigate the problem of salt accumulation in the reuse of treated brewery effluent in agriculture and aquaculture. This research demonstrates the baseline information for such modelling and optimisation. African catfish (Clarias gariepinus) grew in CW treated brewery effluent; however, this growth was moderate at 0.92% bw day-1, whereas Mozambique tilapia (Oreochromis mossambicus) were shown to be unsuited to growth in this system and lost weight with an average specific growth rate (SGR) of -0.98% bw day-1; and both fish species presenting with health related concerns. Hardy fish species such as African catfish can be cultured in brewery effluent, but with risk involved. This was a preliminary study to develop parameters for future dimensional analysis modelling to allow optimisation of the CW, based on nutrient removal rates obtained which will allow for improved downstream aquaculture by reducing or eliminating risks presented in this study. This work has also contributed to a foundation for the development of guidelines that use a risk-based approach for water use in aquaculture. Alternatives to the current in place cleaning agents were considered to mitigate the effects of salt accumulation. Sodium is introduced into the effluent via the use of sodium hydroxide and sodium chlorite for cleaning and disinfection in the brewery, as well as through effluent pH adjustment in the AD plant. The widespread use of outdated legacy cleaning systems and pH adjustment regimes is entrenched in the brewery standard operating procedures (SOP). A cost-benefit analysis (CBA) demonstrated that a change of cleaning and disinfecting regimes to hydrogen peroxide in the brewery, and magnesium hydroxide pH adjustment in the effluent treatment plant addresses the sodium issue upstream in the brewery practically eliminating sodium from the effluent. In addition, a life cycle analysis (LCA) was carried out to assess the environmental impacts associated with the alternative cleaning and pH adjustment scenarios. The LCA showed that electricity consumption during use phase of the chemicals for respective purposes, as well as their production activities were major contributors to the significant environmental impact categories that were assessed. The cleaning scenario employing the use of hydrogen peroxide for both cleaning and disinfection was found to be the most environmentally sustainable. This was attributed to the reduced number of chemicals used compared to the other cleaning scenarios. Dolomitic lime was the pH adjustment alternative with the lowest average environmental impact; but, however, had a higher impact on freshwater eutrophication which is of major concern if the effluent will be reused for irrigation. Magnesium hydroxide was therefore considered to be the better option as a sodium hydroxide alternative for pH adjustment. This mitigates salt accumulation, making treated brewery effluent suitable for reuse in high value downstream agriculture and aquaculture, while employing more environmentally sustainable technologies. Notably, this converts brewery effluent from a financial liability to Ibhayi Brewery, into a product containing water and nutrients that generate income, improve food security, and can create employment in downstream agriculture and aquaculture in a sustainable manner. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-10-29
Modifcations to gravitational waves due to matter shells
- Authors: Naidoo, Monogaran
- Date: 2021-10-29
- Subjects: Gravitational waves , General relativity (Physics) , Einstein field equations , Cosmology , Matter shells
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191118 , vital:45062 , 10.21504/10962/191119
- Description: As detections of gravitational waves (GWs) mount, the need to investigate various effects on the propagation of these waves from the time of emission until detection also grows. We investigate how a thin low density dust shell surrounding a gravitational wave source affects the propagation of GWs. The Bondi-Sachs (BS) formalism for the Einstein equations is used for the problem of a gravitational wave (GW) source surrounded by a spherical dust shell. Using linearised perturbation theory, we and the geometry of the regions exterior to, interior to and within the shell. We and that the dust shell causes the gravitational wave to be modified both in magnitude and phase, but without any energy being transferred to or from the dust. This finding is novel. In the context of cosmology, apart from the gravitational redshift, the effects are too small to be measurable; but the effect would be measurable if a GW event were to occur with a source surrounded by a massive shell and with the radius of the shell and the wavelength of the GWs of the same order. We extended our investigation to astrophysical scenarios such as binary black hole (BBH) mergers, binary neutron star (BNS) mergers, and core collapse supernovae (CCSNe). In these scenarios, instead of a monochromatic GW source, as we used in our initial investigation, we consider burst-like GW sources. The thin density shell approach is modified to include thick shells by considering concentric thin shells and integrating. Solutions are then found for these burst-like GW sources using Fourier transforms. We show that GW echoes that are claimed to be present in the Laser Interferometer Gravitational-Wave Observatory (LIGO) data of certain events, could not have been caused by a matter shell. We do and, however, that matter shells surrounding BBH mergers, BNS mergers, and CCSNe could make modifications of order a few percent to a GW signal. These modifications are expected to be measurable in GW data with current detectors if the event is close enough and at a detectable frequency; or in future detectors with increased frequency range and amplitude sensitivity. Substantial use is made of computer algebra in these investigations. In setting the scene for our investigations, we trace the evolution of general relativity (GR) from Einstein's postulation in 1915 to vindication of his theory with the confirmation of the existence of GWs a century later. We discuss the implications of our results to current and future considerations. Calculations of GWs, both analytical and numerical, have normally assumed their propagation from source to a detector on Earth in a vacuum spacetime, and so discounted the effect of intervening matter. As we enter an era of precision GW measurements, it becomes important to quantify any effects due to propagation of GWs through a non-vacuum spacetime Observational confirmation of the modification effect that we and in astrophysical scenarios involving black holes (BHs), neutron stars (NSs) and CCSNe, would also enhance our understanding of the details of the physics of these bodies. , Thesis (PhD) -- Faculty of Science, Mathematics (Pure and Applied), 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Naidoo, Monogaran
- Date: 2021-10-29
- Subjects: Gravitational waves , General relativity (Physics) , Einstein field equations , Cosmology , Matter shells
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191118 , vital:45062 , 10.21504/10962/191119
- Description: As detections of gravitational waves (GWs) mount, the need to investigate various effects on the propagation of these waves from the time of emission until detection also grows. We investigate how a thin low density dust shell surrounding a gravitational wave source affects the propagation of GWs. The Bondi-Sachs (BS) formalism for the Einstein equations is used for the problem of a gravitational wave (GW) source surrounded by a spherical dust shell. Using linearised perturbation theory, we and the geometry of the regions exterior to, interior to and within the shell. We and that the dust shell causes the gravitational wave to be modified both in magnitude and phase, but without any energy being transferred to or from the dust. This finding is novel. In the context of cosmology, apart from the gravitational redshift, the effects are too small to be measurable; but the effect would be measurable if a GW event were to occur with a source surrounded by a massive shell and with the radius of the shell and the wavelength of the GWs of the same order. We extended our investigation to astrophysical scenarios such as binary black hole (BBH) mergers, binary neutron star (BNS) mergers, and core collapse supernovae (CCSNe). In these scenarios, instead of a monochromatic GW source, as we used in our initial investigation, we consider burst-like GW sources. The thin density shell approach is modified to include thick shells by considering concentric thin shells and integrating. Solutions are then found for these burst-like GW sources using Fourier transforms. We show that GW echoes that are claimed to be present in the Laser Interferometer Gravitational-Wave Observatory (LIGO) data of certain events, could not have been caused by a matter shell. We do and, however, that matter shells surrounding BBH mergers, BNS mergers, and CCSNe could make modifications of order a few percent to a GW signal. These modifications are expected to be measurable in GW data with current detectors if the event is close enough and at a detectable frequency; or in future detectors with increased frequency range and amplitude sensitivity. Substantial use is made of computer algebra in these investigations. In setting the scene for our investigations, we trace the evolution of general relativity (GR) from Einstein's postulation in 1915 to vindication of his theory with the confirmation of the existence of GWs a century later. We discuss the implications of our results to current and future considerations. Calculations of GWs, both analytical and numerical, have normally assumed their propagation from source to a detector on Earth in a vacuum spacetime, and so discounted the effect of intervening matter. As we enter an era of precision GW measurements, it becomes important to quantify any effects due to propagation of GWs through a non-vacuum spacetime Observational confirmation of the modification effect that we and in astrophysical scenarios involving black holes (BHs), neutron stars (NSs) and CCSNe, would also enhance our understanding of the details of the physics of these bodies. , Thesis (PhD) -- Faculty of Science, Mathematics (Pure and Applied), 2021
- Full Text:
- Date Issued: 2021-10-29
Museums for the Planet: Critical Realist Philosophy and the Possibility of an Eco-decolonial Museology
- Authors: Jeffery, Thomas Carnegie
- Date: 2021-10-29
- Subjects: Museums Management , Critical realism , Ontology , Decolonization , Organizational change , Social ecology , Eco-decolonial
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192692 , vital:45251 , 10.21504/10962/192692
- Description: This study introduces dialectical critical realism into museology as a philosophical underlabourer for the development of new theoretical potentials for the transformation of museum practice. The idea of the museum is in a moment of fluidity evident in emergent decolonial and ecological perspectives and in the International Council of Museum’s process of redefinition of the museum. The potential to reimagine the museum lacks a coherent philosophical and theoretical foundation. The persistence of museological dualism separates the social from the ecological and absents the emergence of relational modes of thinking and practice. This study conceives an ecological-decolonial or eco-decolonial mode of museology that is disruptive of dualism and generative of relationality, and is thus generative of agency for deeper, more effective and enduring social-ecological justice. The core of this thesis is the development of the eco-decolonial mode of museology through the DCR onto-axiological chain or ‘MELD’ schema. At 1M a depth ontological analysis augmented by interviews with key informants establishes a dialectic of society and ecology in the museological context. 1M surfaces capitalism and the implicit neoliberal ontology of museology as deep causal mechanisms of the 2E persistence of museological human-nature dualism. The paradox of ‘emancipatory neoliberalism’ is a policy-practice contradiction that absents potentials for transformation of the museum and that is held in place by the grounding ontological activity of museology, collection. The 2E perspective on absences enables the emergence of new transformative pathways towards the 3L vision of the eco-decolonial mode of museology as a (4D) new way of thinking and working to resolve neoliberal restrictions. The fundamental 4D change envisioned for museum philosophy, theory and practice is an ontological transformation from traditionalist human-nature dualism to a progressive human-nature dialectic. A case study considers instances where museum workers exercised the agency to expand practice in this way. Future work using the expansive learning methodology of Change Laboratories will develop and implement the potentials generated by the onto-axiological chain for the eco-decolonial mode to bring real change to traditional, dualist museum practice, in order to ensure the relevance and the agency of the museum as a social structure in and for a changing world. , Thesis (PhD) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Jeffery, Thomas Carnegie
- Date: 2021-10-29
- Subjects: Museums Management , Critical realism , Ontology , Decolonization , Organizational change , Social ecology , Eco-decolonial
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192692 , vital:45251 , 10.21504/10962/192692
- Description: This study introduces dialectical critical realism into museology as a philosophical underlabourer for the development of new theoretical potentials for the transformation of museum practice. The idea of the museum is in a moment of fluidity evident in emergent decolonial and ecological perspectives and in the International Council of Museum’s process of redefinition of the museum. The potential to reimagine the museum lacks a coherent philosophical and theoretical foundation. The persistence of museological dualism separates the social from the ecological and absents the emergence of relational modes of thinking and practice. This study conceives an ecological-decolonial or eco-decolonial mode of museology that is disruptive of dualism and generative of relationality, and is thus generative of agency for deeper, more effective and enduring social-ecological justice. The core of this thesis is the development of the eco-decolonial mode of museology through the DCR onto-axiological chain or ‘MELD’ schema. At 1M a depth ontological analysis augmented by interviews with key informants establishes a dialectic of society and ecology in the museological context. 1M surfaces capitalism and the implicit neoliberal ontology of museology as deep causal mechanisms of the 2E persistence of museological human-nature dualism. The paradox of ‘emancipatory neoliberalism’ is a policy-practice contradiction that absents potentials for transformation of the museum and that is held in place by the grounding ontological activity of museology, collection. The 2E perspective on absences enables the emergence of new transformative pathways towards the 3L vision of the eco-decolonial mode of museology as a (4D) new way of thinking and working to resolve neoliberal restrictions. The fundamental 4D change envisioned for museum philosophy, theory and practice is an ontological transformation from traditionalist human-nature dualism to a progressive human-nature dialectic. A case study considers instances where museum workers exercised the agency to expand practice in this way. Future work using the expansive learning methodology of Change Laboratories will develop and implement the potentials generated by the onto-axiological chain for the eco-decolonial mode to bring real change to traditional, dualist museum practice, in order to ensure the relevance and the agency of the museum as a social structure in and for a changing world. , Thesis (PhD) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
Neutral Atomic Hydrogen in Gravitationally Lensed Systems
- Authors: Blecher, Tariq Dylan
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192776 , vital:45263
- Description: Thesis (PhD) -- Faculty of Law, Law, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Blecher, Tariq Dylan
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192776 , vital:45263
- Description: Thesis (PhD) -- Faculty of Law, Law, 2021
- Full Text:
- Date Issued: 2021-10-29
On the gravitational dual to strongly coupled fluids
- Authors: Shawa, Mark Musonda Webster
- Date: 2021-10-29
- Subjects: Quantum gravity , String models , Gauge fields (Physics) , Scattering amplitude (Nuclear physics) , Quark-gluon plasma , Anti-de Sitter/Conformal Field Theory (AdS/CFT) , Gauge/gravity duality
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192933 , vital:45280 , 10.21504/10962/192933
- Description: This thesis discusses the prospect of finding the gravitational dual to the strongly coupled conformal fluids, with a special interest in the quark-gluon plasma. Such a task can be achieved by matching certain physical observables of two apparently different theories that are dually related owing to the fact that the same string theory can be viewed in two different ways. This is particularly useful when one of the theories is intractable while its dual is manageable. We begin by postulating a particular type of gravitational theory from which we determine graviton scattering amplitudes in a special regime of high momentum. Using the gauge–gravity duality dictionary, the graviton scattering amplitudes can be mapped to stress-tensor correlation functions in the gauge theory. One of the outcomes of high-energy scattering experiments involving the quark-gluon plasma is stress-tensor correlator data. This thesis provides an algorithm for matching graviton scattering amplitudes with stress-tensor correlator data which, in principle, can be used to identify the gravitational dual to the quark-gluon plasma. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Shawa, Mark Musonda Webster
- Date: 2021-10-29
- Subjects: Quantum gravity , String models , Gauge fields (Physics) , Scattering amplitude (Nuclear physics) , Quark-gluon plasma , Anti-de Sitter/Conformal Field Theory (AdS/CFT) , Gauge/gravity duality
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192933 , vital:45280 , 10.21504/10962/192933
- Description: This thesis discusses the prospect of finding the gravitational dual to the strongly coupled conformal fluids, with a special interest in the quark-gluon plasma. Such a task can be achieved by matching certain physical observables of two apparently different theories that are dually related owing to the fact that the same string theory can be viewed in two different ways. This is particularly useful when one of the theories is intractable while its dual is manageable. We begin by postulating a particular type of gravitational theory from which we determine graviton scattering amplitudes in a special regime of high momentum. Using the gauge–gravity duality dictionary, the graviton scattering amplitudes can be mapped to stress-tensor correlation functions in the gauge theory. One of the outcomes of high-energy scattering experiments involving the quark-gluon plasma is stress-tensor correlator data. This thesis provides an algorithm for matching graviton scattering amplitudes with stress-tensor correlator data which, in principle, can be used to identify the gravitational dual to the quark-gluon plasma. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-10-29
Phthalocyanine-nanoparticle conjugates supported on inorganic nanofibers as photocatalysts for the treatment of biological and organic pollutants as well as for hydrogen generation
- Authors: Mapukata, Sivuyisiwe
- Date: 2021-10-29
- Subjects: Phthalocyanines , Nanofibers , Nanoparticles , Zinc , Hydrogen , Organic water pollutants , Water Purification , Electrospinning , Photocatalysis , Photodegradation , Anti-infective agents
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192831 , vital:45268 , 10.21504/10962/192831
- Description: This thesis reports on the synthesis, photophysicochemical and photocatalytic properties of various zinc phthalocyanines (Pcs). For enhanced properties and catalyst support, the reported Pcs were conjugated to different nanoparticles (NPs) through chemisorption as well as amide bond formation to yield Pc-NP conjugates. For increased catalyst surface area and catalyst reusability, the Pcs and some of their conjugates were also supported on electrospun inorganic nanofibers i.e. SiO2, hematite (abbreviated Hem and has formula α-Fe2O3), ZnO and TiO2 nanofibers. The effect that the number of charges on a Pc has on its antimicrobial activities was evaluated by comparing the photoactivities of neutral, octacationic and hexadecacationic Pcs against S. aureus, E. coli and C. albicans. The extent of enhancement of their antimicrobial activities upon conjugation (through chemisorption) to Ag NPs was also studied in solution and when supported on SiO2 nanofibers. The results showed that the hexadecacationic complex 3 possessed the best antimicrobial activity against all three microorganisms, in solution and when supported on the SiO2 nanofibers. Covalent conjugation of Pcs with carboxylic acid moieties (complexes 4-6) to amine functionalised NPs (Cys-Ag, NH2-Fe3O4 and Cys-Fe3O4@Ag) resulted in enhanced singlet oxygen generation and thus antibacterial efficiencies. Comparison of the photodegradation efficiencies of semiconductor nanofibers (hematite, ZnO and TiO2) when bare and when modified with a Pc (complex 6) were evaluated. Modification of the nanofibers with the Pc resulted in enhanced photoactivities for the nanofibers with the hematite nanofibers being the best. Modification of the hematite nanofibers with two different Pcs i.e. monosubstituted (complex 5) and an asymmetrical tetrasubstituted Pc (complex 6) showed that complex 6 better enhanced the activity of the nanofibers. Evaluation of the hydrogen generation efficiencies of the bare and modified TiO2 nanofibers calcined at different temperatures demonstrated that the anatase nanofibers calcined at 500 oC possessed the best catalytic efficiency. The efficiency of the TiO2 nanofibers was enhanced in the presence of the Co and Pd NPs as well as a Pc (complex 7), with the extent of enhancement being the greatest for the nanofibers modified with the Pd NPs. The reported findings therefore demonstrate the versatility of applications of Pcs for different water purification techniques when supported on different nanomaterials. , Thesis (PhD) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Mapukata, Sivuyisiwe
- Date: 2021-10-29
- Subjects: Phthalocyanines , Nanofibers , Nanoparticles , Zinc , Hydrogen , Organic water pollutants , Water Purification , Electrospinning , Photocatalysis , Photodegradation , Anti-infective agents
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192831 , vital:45268 , 10.21504/10962/192831
- Description: This thesis reports on the synthesis, photophysicochemical and photocatalytic properties of various zinc phthalocyanines (Pcs). For enhanced properties and catalyst support, the reported Pcs were conjugated to different nanoparticles (NPs) through chemisorption as well as amide bond formation to yield Pc-NP conjugates. For increased catalyst surface area and catalyst reusability, the Pcs and some of their conjugates were also supported on electrospun inorganic nanofibers i.e. SiO2, hematite (abbreviated Hem and has formula α-Fe2O3), ZnO and TiO2 nanofibers. The effect that the number of charges on a Pc has on its antimicrobial activities was evaluated by comparing the photoactivities of neutral, octacationic and hexadecacationic Pcs against S. aureus, E. coli and C. albicans. The extent of enhancement of their antimicrobial activities upon conjugation (through chemisorption) to Ag NPs was also studied in solution and when supported on SiO2 nanofibers. The results showed that the hexadecacationic complex 3 possessed the best antimicrobial activity against all three microorganisms, in solution and when supported on the SiO2 nanofibers. Covalent conjugation of Pcs with carboxylic acid moieties (complexes 4-6) to amine functionalised NPs (Cys-Ag, NH2-Fe3O4 and Cys-Fe3O4@Ag) resulted in enhanced singlet oxygen generation and thus antibacterial efficiencies. Comparison of the photodegradation efficiencies of semiconductor nanofibers (hematite, ZnO and TiO2) when bare and when modified with a Pc (complex 6) were evaluated. Modification of the nanofibers with the Pc resulted in enhanced photoactivities for the nanofibers with the hematite nanofibers being the best. Modification of the hematite nanofibers with two different Pcs i.e. monosubstituted (complex 5) and an asymmetrical tetrasubstituted Pc (complex 6) showed that complex 6 better enhanced the activity of the nanofibers. Evaluation of the hydrogen generation efficiencies of the bare and modified TiO2 nanofibers calcined at different temperatures demonstrated that the anatase nanofibers calcined at 500 oC possessed the best catalytic efficiency. The efficiency of the TiO2 nanofibers was enhanced in the presence of the Co and Pd NPs as well as a Pc (complex 7), with the extent of enhancement being the greatest for the nanofibers modified with the Pd NPs. The reported findings therefore demonstrate the versatility of applications of Pcs for different water purification techniques when supported on different nanomaterials. , Thesis (PhD) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10-29