Redefinition of a refugee during conditions of disaster uncertainty of COVID19 in South Africa and beyond
- Authors: Maguire, Kelly Ann
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/461841 , vital:76244
- Description: Access restricited. Expected release date 2026. , Thesis (Msc (Pharmacy)) -- Faculty of Pharmacy, Pharmacy, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Maguire, Kelly Ann
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/461841 , vital:76244
- Description: Access restricited. Expected release date 2026. , Thesis (Msc (Pharmacy)) -- Faculty of Pharmacy, Pharmacy, 2024
- Full Text:
- Date Issued: 2024-10-11
Relationship between oil price changes and the South African stock market returns: a nonlinear ARDL analysis
- Authors: Habana, Athenkosi
- Date: 2024-10-11
- Subjects: Stock market index South Africa , Stock exchanges South Africa , Petroleum products Prices South Africa , Autoregression (Statistics) , JSE Securities Exchange South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/462713 , vital:76328
- Description: Understanding the factors that influence oil price volatility and how they affect the stock market is crucial for decision-making, planning, and forecasting by governments, companies, and individuals. The aim of this study is to analyze the relationship between oil prices and stock market returns of selected JSE stock indices. A nonlinear ARDL model is used to study the interaction between changes in oil prices and the South African stock market. Monthly data covering the period from January 2010 to December 2022 is utilized in the study. The main findings of the study show that in the short run negative changes in oil prices have a statistically significant positive impact that on stock returns of the All-Share, Financials and Resources indices, while it is insignificant for the Industrials index stock returns. On the other hand, positive changes in oil prices have a negative and insignificant impact on all the stock returns of the indices. Therefore, in the short-run there is no nonlinear relationship between oil prices and the stock returns of the indices. In the long-run, the impact of oil prices on stock returns of the All Share, Financials and Resources indices is nonlinear or asymmetric. The impact of oil price changes on the stock indices varies across the indices. An increase in oil prices has a negative and statistically significant impact on stock returns of the All Share, Financials and Resources index. Conversely, a decrease in oil prices has a positive and significant impact on All Share, Financials and Resources index stock returns in the long-run. The impact of positive and negative changes in oil prices is insignificant for the Industrials index stock returns. Therefore, these finding makes it possible for investors or portfolio managers to better mitigate the negative consequences of unforeseen events and adapt their investment plans to hedge against variations in the price of oil. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Habana, Athenkosi
- Date: 2024-10-11
- Subjects: Stock market index South Africa , Stock exchanges South Africa , Petroleum products Prices South Africa , Autoregression (Statistics) , JSE Securities Exchange South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/462713 , vital:76328
- Description: Understanding the factors that influence oil price volatility and how they affect the stock market is crucial for decision-making, planning, and forecasting by governments, companies, and individuals. The aim of this study is to analyze the relationship between oil prices and stock market returns of selected JSE stock indices. A nonlinear ARDL model is used to study the interaction between changes in oil prices and the South African stock market. Monthly data covering the period from January 2010 to December 2022 is utilized in the study. The main findings of the study show that in the short run negative changes in oil prices have a statistically significant positive impact that on stock returns of the All-Share, Financials and Resources indices, while it is insignificant for the Industrials index stock returns. On the other hand, positive changes in oil prices have a negative and insignificant impact on all the stock returns of the indices. Therefore, in the short-run there is no nonlinear relationship between oil prices and the stock returns of the indices. In the long-run, the impact of oil prices on stock returns of the All Share, Financials and Resources indices is nonlinear or asymmetric. The impact of oil price changes on the stock indices varies across the indices. An increase in oil prices has a negative and statistically significant impact on stock returns of the All Share, Financials and Resources index. Conversely, a decrease in oil prices has a positive and significant impact on All Share, Financials and Resources index stock returns in the long-run. The impact of positive and negative changes in oil prices is insignificant for the Industrials index stock returns. Therefore, these finding makes it possible for investors or portfolio managers to better mitigate the negative consequences of unforeseen events and adapt their investment plans to hedge against variations in the price of oil. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
- Full Text:
- Date Issued: 2024-10-11
Research-informed development of comprehensible isiXhosa teaching material: the Department of Basic Education Mental Starters doubling and halving unit
- Authors: Booi, Tabisa
- Date: 2024-10-11
- Subjects: Native language and education South Africa , Mathematics Translating South Africa , South Africa. Department of Basic Education , Translanguaging (Linguistics) , Mathematics Study and teaching (Elementary) South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463680 , vital:76431
- Description: One of the challenges faced by schools that teach in isiXhosa in the Foundation Phase is the impact of nature of language used in the early-grade mathematics classroom. This is the focus of this research study. Despite numerous programs addressing the poor performance in mathematics, a significant majority of interventions are presented in English, creating barriers for learners and teachers using their native languages. While the Language in Education Policy allows for home language instruction in isiXhosa, the translation of materials often contains distortion in meaning and unfamiliar terms, complicating comprehension for indigenous language learners. Motivated by concerns over low mathematics performance, as highlighted in TIMSS (2019), and my personal experiences in teaching Foundation Phase mathematics in isiXhosa at a rural primary school, this study explores the challenges arising from using translated materials. The use of mediating materials in isiXhosa can be hindered by unfamiliar terms and distortion in meaning. For this reason, I adopted a translanguaging approach, incorporating transliteration between English and isiXhosa, especially in mathematics teaching. Grounded in the pragmatism paradigm, this qualitative design research unfolds in an isiXhosa medium primary school in Makhanda. The investigation centers first on document analysis of the Doubling and Halving unit in the Mental Starters Assessment Programme (MSAP) Teacher Guide (in English and isiXhosa), and then focuses on the teaching of two grade 3 classes, in isiXhosa, using the MSAP Doubling and Halving teaching sequence. Two grade 3 teachers and their principal participate as critical friends. The key research questions are: (1) What are the enablers and constraints that are experienced by the teacher during the mediation of the doubling and halving calculating strategies in isiXhosa?; (2) What are the key terms and phrases (vocabulary) needed to teach doubling and halving in isiXhosa?; (3) What are the perspectives and pedagogical insights of the critical friends on the isiXhosa vocabulary that was developed? The research unfolds in multiple stages, beginning with a document analysis of the MSAP using Toury’s Descriptive Translation Studies. Subsequently, I adapt eight lesson starters for doubling and halving, implementing them across two grade 3 classes in a double action research cycle. Focus group discussions with critical friends, aided by video recordings for stimulated recall, provide valuable insights. Data collected throughout these stages are analyzed through the lens of Vygotsky’s Socio-Cultural theory, contributing to a comprehensive understanding of the challenges and potential solutions in this educational context. , Thesis (MEd) -- Faculty of Education, Primary and Early Childhood Education, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Booi, Tabisa
- Date: 2024-10-11
- Subjects: Native language and education South Africa , Mathematics Translating South Africa , South Africa. Department of Basic Education , Translanguaging (Linguistics) , Mathematics Study and teaching (Elementary) South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463680 , vital:76431
- Description: One of the challenges faced by schools that teach in isiXhosa in the Foundation Phase is the impact of nature of language used in the early-grade mathematics classroom. This is the focus of this research study. Despite numerous programs addressing the poor performance in mathematics, a significant majority of interventions are presented in English, creating barriers for learners and teachers using their native languages. While the Language in Education Policy allows for home language instruction in isiXhosa, the translation of materials often contains distortion in meaning and unfamiliar terms, complicating comprehension for indigenous language learners. Motivated by concerns over low mathematics performance, as highlighted in TIMSS (2019), and my personal experiences in teaching Foundation Phase mathematics in isiXhosa at a rural primary school, this study explores the challenges arising from using translated materials. The use of mediating materials in isiXhosa can be hindered by unfamiliar terms and distortion in meaning. For this reason, I adopted a translanguaging approach, incorporating transliteration between English and isiXhosa, especially in mathematics teaching. Grounded in the pragmatism paradigm, this qualitative design research unfolds in an isiXhosa medium primary school in Makhanda. The investigation centers first on document analysis of the Doubling and Halving unit in the Mental Starters Assessment Programme (MSAP) Teacher Guide (in English and isiXhosa), and then focuses on the teaching of two grade 3 classes, in isiXhosa, using the MSAP Doubling and Halving teaching sequence. Two grade 3 teachers and their principal participate as critical friends. The key research questions are: (1) What are the enablers and constraints that are experienced by the teacher during the mediation of the doubling and halving calculating strategies in isiXhosa?; (2) What are the key terms and phrases (vocabulary) needed to teach doubling and halving in isiXhosa?; (3) What are the perspectives and pedagogical insights of the critical friends on the isiXhosa vocabulary that was developed? The research unfolds in multiple stages, beginning with a document analysis of the MSAP using Toury’s Descriptive Translation Studies. Subsequently, I adapt eight lesson starters for doubling and halving, implementing them across two grade 3 classes in a double action research cycle. Focus group discussions with critical friends, aided by video recordings for stimulated recall, provide valuable insights. Data collected throughout these stages are analyzed through the lens of Vygotsky’s Socio-Cultural theory, contributing to a comprehensive understanding of the challenges and potential solutions in this educational context. , Thesis (MEd) -- Faculty of Education, Primary and Early Childhood Education, 2024
- Full Text:
- Date Issued: 2024-10-11
Restless imagination: material, urban space and contemporary art practices in postcolonial Harare
- Authors: Zhang, Lifang
- Date: 2024-10-11
- Subjects: African art , Art, Modern 21st century , Materiality , Zimbabwean art , Public spaces in art Zimbabwe Harare , Found objects (Art)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/467061 , vital:76811 , DOI htps://doi.org/10.21504/10962/467061
- Description: The use of everyday objects as art materials has evolved into a contemporary phenomenon in Africa, deeply rooted in specific contexts and possessing global relevance. Despite limited scholarly attention, existing discussions tend to revolve around individual artists or particular mediums. Many discourses are associated with either the prevailing universalist perspective that views the trend as Western avant-garde derivation or the reductionist narrative that attributes it merely to local material scarcity. There exists a critical need to investigate historical genealogies and explore the theoretical frameworks essential for comprehending this phenomenon. Through a combination of visual analysis, fieldwork and interviews, this thesis conducts an in-depth examination of the use of found materials in Zimbabwe, exploring its historiography, mechanism, impact, and visual achievements. This thesis situates the investigation in postcolonial Harare, the city that profoundly shaped the evolution of the phenomenon of using found materials. Regarding timeframe, this thesis examines contemporary Zimbabwean artists’ practices, with a special emphasis on the period following the Redefinitions movement in the early 2000s. However, it also explores the pioneering material innovations of Tapfuma Gutsa and Keston Beaton, as well as analyses the importance of the Pachipamwe workshop between the 1980s and 1990s. Among the artists, it highlights those who consistently engage with found materials and delve into their interactions with urban spaces in their practices. With the city as the analytical framework, this thesis draws on debates centring on contemporary African art and theories about materiality and urban studies. Approaching found materials as the materiality of both art and the city, it reveals a convergence of various interrelated artistic practices in Harare. The multidimensional relationships are manifested in the artistic processes, where the collection of materials, the creation of artworks, and collaboration with diverse urban groups, are intricately linked to urban spaces in Harare. By unfolding this process and emphasising the labour of artists, this thesis transcends conventional perceptions of artworks as mere visual objects, revealing the societal and spatial interactions inherent in artistic practices involving found materials. This thesis also explores the visual and semantical interactions between art and the city, centring on a curated array of artworks which is not merely a visual representation or reflection of the city but also provides critical thoughts on and dialogues with the city, as well as (re)imaginations and aspirations of the urban landscape. The relationship between art and the city is further deepened through iii artistic practices, extending beyond the creation of artworks and involving art infrastructure building in Harare. This thesis conceptualises artists’ practices of working with found material as restless imagination, a term drawn from the name of the city, which refers to “no one sleeps” in the Shona language. The restlessness embedded in its naming has characterised the city in various dimensions and across time, with the haunting colonial legacy, ongoing urban crises, ubiquitous movements and the ordinary people’s unwavering efforts for liberation and survival. Artists residing in postcolonial Harare also adopt and cultivate restlessness as a working strategy not only to cope with but also to transgress such conditions. The evolution of found materials has been unfolded through a continuous process of restless imagination and innovative manoeuvres, which are embodied in the continual re-imagination of the convention of art materials, the expressive capacities of specific materials, and a commitment to labour throughout the transformative process. This open-ended though productive process of exploration perpetuates and extends to the re-imagination and reclaiming of urban spaces, transforming them into artistic spaces that foster artistic creation and the reproduction of artists and imaginations. This thesis argues the potential framing and comprehension of Harare city as the site of restless imagination pursued, embodied and materialised by artists through their artwork and engagement with urban spaces. Contemporary Zimbabwean artists have redefined their artistic practices, interacting with the materiality of everyday urban life, urban matters, urban spaces, and urban communities, and, concurrently, the relationship between art and city, art and society. By doing so, they open up space for possibilities to refashion the restless city, negotiate urban citizenship, and recreate themselves as agentive subjects in postcolonial Harare. It could be argued that artists, as urban citizens, akin to other residents grappling with everyday life in the city, also exercise their arts of citizenship through their creative innovations in artistic expression and practices. Therefore, this thesis not only delves into the contextualisation of artistic practices in Harare but also contributes to broader discussions on everyday practices in African cities through the lens of art. , Thesis (PhD) -- Faculty of Humanities, Fine Art, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Zhang, Lifang
- Date: 2024-10-11
- Subjects: African art , Art, Modern 21st century , Materiality , Zimbabwean art , Public spaces in art Zimbabwe Harare , Found objects (Art)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/467061 , vital:76811 , DOI htps://doi.org/10.21504/10962/467061
- Description: The use of everyday objects as art materials has evolved into a contemporary phenomenon in Africa, deeply rooted in specific contexts and possessing global relevance. Despite limited scholarly attention, existing discussions tend to revolve around individual artists or particular mediums. Many discourses are associated with either the prevailing universalist perspective that views the trend as Western avant-garde derivation or the reductionist narrative that attributes it merely to local material scarcity. There exists a critical need to investigate historical genealogies and explore the theoretical frameworks essential for comprehending this phenomenon. Through a combination of visual analysis, fieldwork and interviews, this thesis conducts an in-depth examination of the use of found materials in Zimbabwe, exploring its historiography, mechanism, impact, and visual achievements. This thesis situates the investigation in postcolonial Harare, the city that profoundly shaped the evolution of the phenomenon of using found materials. Regarding timeframe, this thesis examines contemporary Zimbabwean artists’ practices, with a special emphasis on the period following the Redefinitions movement in the early 2000s. However, it also explores the pioneering material innovations of Tapfuma Gutsa and Keston Beaton, as well as analyses the importance of the Pachipamwe workshop between the 1980s and 1990s. Among the artists, it highlights those who consistently engage with found materials and delve into their interactions with urban spaces in their practices. With the city as the analytical framework, this thesis draws on debates centring on contemporary African art and theories about materiality and urban studies. Approaching found materials as the materiality of both art and the city, it reveals a convergence of various interrelated artistic practices in Harare. The multidimensional relationships are manifested in the artistic processes, where the collection of materials, the creation of artworks, and collaboration with diverse urban groups, are intricately linked to urban spaces in Harare. By unfolding this process and emphasising the labour of artists, this thesis transcends conventional perceptions of artworks as mere visual objects, revealing the societal and spatial interactions inherent in artistic practices involving found materials. This thesis also explores the visual and semantical interactions between art and the city, centring on a curated array of artworks which is not merely a visual representation or reflection of the city but also provides critical thoughts on and dialogues with the city, as well as (re)imaginations and aspirations of the urban landscape. The relationship between art and the city is further deepened through iii artistic practices, extending beyond the creation of artworks and involving art infrastructure building in Harare. This thesis conceptualises artists’ practices of working with found material as restless imagination, a term drawn from the name of the city, which refers to “no one sleeps” in the Shona language. The restlessness embedded in its naming has characterised the city in various dimensions and across time, with the haunting colonial legacy, ongoing urban crises, ubiquitous movements and the ordinary people’s unwavering efforts for liberation and survival. Artists residing in postcolonial Harare also adopt and cultivate restlessness as a working strategy not only to cope with but also to transgress such conditions. The evolution of found materials has been unfolded through a continuous process of restless imagination and innovative manoeuvres, which are embodied in the continual re-imagination of the convention of art materials, the expressive capacities of specific materials, and a commitment to labour throughout the transformative process. This open-ended though productive process of exploration perpetuates and extends to the re-imagination and reclaiming of urban spaces, transforming them into artistic spaces that foster artistic creation and the reproduction of artists and imaginations. This thesis argues the potential framing and comprehension of Harare city as the site of restless imagination pursued, embodied and materialised by artists through their artwork and engagement with urban spaces. Contemporary Zimbabwean artists have redefined their artistic practices, interacting with the materiality of everyday urban life, urban matters, urban spaces, and urban communities, and, concurrently, the relationship between art and city, art and society. By doing so, they open up space for possibilities to refashion the restless city, negotiate urban citizenship, and recreate themselves as agentive subjects in postcolonial Harare. It could be argued that artists, as urban citizens, akin to other residents grappling with everyday life in the city, also exercise their arts of citizenship through their creative innovations in artistic expression and practices. Therefore, this thesis not only delves into the contextualisation of artistic practices in Harare but also contributes to broader discussions on everyday practices in African cities through the lens of art. , Thesis (PhD) -- Faculty of Humanities, Fine Art, 2024
- Full Text:
- Date Issued: 2024-10-11
RU sleepy? - sleep/wake characteristics and sleep quality among undergraduate students attending Rhodes University
- Authors: Young, Celine Brittany
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464776 , vital:76544
- Description: Background: University students, specifically older adolescents and young adults, are at high risk of insufficient and poor-quality sleep due to age-related biological changes converging with several systemic factors unique to the university context. These include but are not limited to freedom and independence, communal living environments, academic demands and associated stress, erratic schedules, and high technology use. While there has been extensive research on sleep quality in students in other parts of the world, there has been comparatively less in South Africa, which may present unique contextual influencing factors. Thus, this study aimed to characterise sleep/wake characteristics and sleep quality in a sample of undergraduate students attending a South African University. Additionally, the study aimed to determine the impact of certain demographic factors on sleep quality in the students. Lastly, the current study aimed to determine what factors may influence the students' sleep quality. Method: This study adopted a cross-sectional design and explored sleep quality and sleep/wake characteristics (e.g., bedtimes, rise times, sleep duration, sleep latency, etc.) through an online survey circulated amongst undergraduate students via Rhodes university email platforms and student social media pages. The testing period started on 15 August 2022 and continued until 8 October 2022. The survey consisted of three main sections: (1) socio-demographic factors; (2) the Pittsburgh Sleep Quality Index (PSQI); (3) an open-ended question that asked students to comment on the factors which they felt may be influencing their sleep over the previous month. Results: 393 students participated in this study, which corresponds to a response rate of 6.30%. The results revealed notable levels of poor sleep quality (mean global score of 9.79 (±3.36)) and a high prevalence of poor sleepers within the whole sample (over 90%), as well as across different demographic groups. Analysis indicated poor overall sleep quality, and concerning sleep/wake characteristics, such as, bedtimes, rise times, sleep latency, time in bed, habitual sleep efficiency, sleep duration, etc. Additionally, participants reported extended sleep latencies and difficulties initiating sleep within 30 minutes. Daytime dysfunction was prominent, indicating challenges in daily functioning. Demographic comparisons revealed that male students generally reported better subjective sleep quality and lower global PSQI scores than female students, with 2 females presenting with poorer sleep quality overall. Students living in university residences reported significantly later bedtimes and shorter sleep durations than off- campus students. Regarding year of study, third-year students reported better subjective sleep quality, longer times in bed, longer sleep durations and overall better sleep quality than first- and second-year students. Regarding funding mechanisms, students on the National Students Financial Aid Scheme had significantly higher subjective sleep quality scores but later bedtimes than students in the "other" funding groups. Thematic analysis revealed that several self-reported factors impacted student sleep negatively. Mental health issues were the most commonly cited theme (26.72% of students), which included anxiety, stress, worry, and overthinking. University-related factors were the second most frequently cited theme (25.49% encompassing academics, funding, and navigating university life). Environmental influences comprised of issues with noise, particularly in university residences, weather, and lighting. Discussion: In sum, the results of this study indicate that in this sample, the drivers of poor sleep quality seemed to be late bedtimes, early rise times, prolonged sleep latency, frequent night awakenings, and overall short sleep duration, all of which were driven by several systemic factors. These findings underscore the importance of assessing sleep health beyond just sleep duration and indicate compromised sleep health within this population, evidenced by high levels of daytime dysfunction due to inadequate and poor-quality sleep. The challenges faced by university students extend across various aspects of their lives, including sleep health, with poor sleep quality and insufficient sleep having significant implications for academic performance, mental health, and overall well-being as they transition into adulthood. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Young, Celine Brittany
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464776 , vital:76544
- Description: Background: University students, specifically older adolescents and young adults, are at high risk of insufficient and poor-quality sleep due to age-related biological changes converging with several systemic factors unique to the university context. These include but are not limited to freedom and independence, communal living environments, academic demands and associated stress, erratic schedules, and high technology use. While there has been extensive research on sleep quality in students in other parts of the world, there has been comparatively less in South Africa, which may present unique contextual influencing factors. Thus, this study aimed to characterise sleep/wake characteristics and sleep quality in a sample of undergraduate students attending a South African University. Additionally, the study aimed to determine the impact of certain demographic factors on sleep quality in the students. Lastly, the current study aimed to determine what factors may influence the students' sleep quality. Method: This study adopted a cross-sectional design and explored sleep quality and sleep/wake characteristics (e.g., bedtimes, rise times, sleep duration, sleep latency, etc.) through an online survey circulated amongst undergraduate students via Rhodes university email platforms and student social media pages. The testing period started on 15 August 2022 and continued until 8 October 2022. The survey consisted of three main sections: (1) socio-demographic factors; (2) the Pittsburgh Sleep Quality Index (PSQI); (3) an open-ended question that asked students to comment on the factors which they felt may be influencing their sleep over the previous month. Results: 393 students participated in this study, which corresponds to a response rate of 6.30%. The results revealed notable levels of poor sleep quality (mean global score of 9.79 (±3.36)) and a high prevalence of poor sleepers within the whole sample (over 90%), as well as across different demographic groups. Analysis indicated poor overall sleep quality, and concerning sleep/wake characteristics, such as, bedtimes, rise times, sleep latency, time in bed, habitual sleep efficiency, sleep duration, etc. Additionally, participants reported extended sleep latencies and difficulties initiating sleep within 30 minutes. Daytime dysfunction was prominent, indicating challenges in daily functioning. Demographic comparisons revealed that male students generally reported better subjective sleep quality and lower global PSQI scores than female students, with 2 females presenting with poorer sleep quality overall. Students living in university residences reported significantly later bedtimes and shorter sleep durations than off- campus students. Regarding year of study, third-year students reported better subjective sleep quality, longer times in bed, longer sleep durations and overall better sleep quality than first- and second-year students. Regarding funding mechanisms, students on the National Students Financial Aid Scheme had significantly higher subjective sleep quality scores but later bedtimes than students in the "other" funding groups. Thematic analysis revealed that several self-reported factors impacted student sleep negatively. Mental health issues were the most commonly cited theme (26.72% of students), which included anxiety, stress, worry, and overthinking. University-related factors were the second most frequently cited theme (25.49% encompassing academics, funding, and navigating university life). Environmental influences comprised of issues with noise, particularly in university residences, weather, and lighting. Discussion: In sum, the results of this study indicate that in this sample, the drivers of poor sleep quality seemed to be late bedtimes, early rise times, prolonged sleep latency, frequent night awakenings, and overall short sleep duration, all of which were driven by several systemic factors. These findings underscore the importance of assessing sleep health beyond just sleep duration and indicate compromised sleep health within this population, evidenced by high levels of daytime dysfunction due to inadequate and poor-quality sleep. The challenges faced by university students extend across various aspects of their lives, including sleep health, with poor sleep quality and insufficient sleep having significant implications for academic performance, mental health, and overall well-being as they transition into adulthood. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2024
- Full Text:
- Date Issued: 2024-10-11
Screening and characterisation of novel compounds and their derivatives from South African medicinal plants against triple negative breast cancer cells
- Authors: Nyemba, Getrude Rutendo
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463952 , vital:76460
- Description: Access restricted. Expected release in 2026. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology & Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Nyemba, Getrude Rutendo
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463952 , vital:76460
- Description: Access restricted. Expected release in 2026. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology & Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
Screening for inhibitors of the Mycobacterium tuberculosis DnaK-DnaJ-GrpE complex
- Authors: John, Ruth Omoti
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466491 , vital:76735
- Description: Restricted access. Expected release in 2026. , Thesis (PhD) -- Faculty of Science, Biochemistry, Microbiology and Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: John, Ruth Omoti
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466491 , vital:76735
- Description: Restricted access. Expected release in 2026. , Thesis (PhD) -- Faculty of Science, Biochemistry, Microbiology and Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
Search for acrylonitrile-based inhibitors of SAR-Cov-19 main and papain-like proteases through covalent docking and high-throughput virtual screening
- Authors: Ntantiso, Yamkela
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463941 , vital:76459
- Description: The sudden outbreak of SARS-CoV-2 formerly known as the 2019 novel coronavirus (2019-nCoV) quickly turned into a pandemic of coronavirus disease 2019 (COVID-19), the scale of which has never been seen before. High infection rates and mortality from COVID-19 placed pressure on global health services, and this has been to the detriment of the global economy. However, treatment options for COVID-19 are still very limited; hence, it is now as important as ever that researchers explore searching for new compounds with pharmacokinetic properties that inhibit the two COVID proteases - the main protease (Mpro) and the papain-like protease (PLpro). The main protease is a cysteine protease; as such, it is susceptible to permanent inhibition by reactive species (warheads) that may covalently bind to cysteine residues. One such class of compounds is acrylonitriles, in which the reactive acrylonitrile is reactive towards cysteine through a Michael addition reaction. The resulting covalent interaction is permanent and inactivates the cysteine residue and hence the protease within the context of the COVID-19 life-cycle. In this context, this study seeks to utilize computational-based approaches to identify acrylonitrile-based inhibitors of coronavirus drug targets. To do this, the ZINC database has been screened for compounds containing acrylonitrile functionality, due to its known nature as a warhead that binds to cysteine residues. Pharmacokinetic properties are computed to evaluate the viability of identified inhibitors, and covalent and non-covalent molecular docking approaches to the Mpro enzyme crystal structure have also been used to assess the identified systems. To gather more information and evaluate the most promising systems, a subset of the most promising compounds have been subjected to molecular dynamics simulation (for both covalently bound and non-covalently bound systems). , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology & Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Ntantiso, Yamkela
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463941 , vital:76459
- Description: The sudden outbreak of SARS-CoV-2 formerly known as the 2019 novel coronavirus (2019-nCoV) quickly turned into a pandemic of coronavirus disease 2019 (COVID-19), the scale of which has never been seen before. High infection rates and mortality from COVID-19 placed pressure on global health services, and this has been to the detriment of the global economy. However, treatment options for COVID-19 are still very limited; hence, it is now as important as ever that researchers explore searching for new compounds with pharmacokinetic properties that inhibit the two COVID proteases - the main protease (Mpro) and the papain-like protease (PLpro). The main protease is a cysteine protease; as such, it is susceptible to permanent inhibition by reactive species (warheads) that may covalently bind to cysteine residues. One such class of compounds is acrylonitriles, in which the reactive acrylonitrile is reactive towards cysteine through a Michael addition reaction. The resulting covalent interaction is permanent and inactivates the cysteine residue and hence the protease within the context of the COVID-19 life-cycle. In this context, this study seeks to utilize computational-based approaches to identify acrylonitrile-based inhibitors of coronavirus drug targets. To do this, the ZINC database has been screened for compounds containing acrylonitrile functionality, due to its known nature as a warhead that binds to cysteine residues. Pharmacokinetic properties are computed to evaluate the viability of identified inhibitors, and covalent and non-covalent molecular docking approaches to the Mpro enzyme crystal structure have also been used to assess the identified systems. To gather more information and evaluate the most promising systems, a subset of the most promising compounds have been subjected to molecular dynamics simulation (for both covalently bound and non-covalently bound systems). , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology & Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
Sediment and associated phosphorus dynamics in meandering floodplain wetlands in the Tsitsa River catchment
- Authors: Schlegel, Philippa Kirsten
- Date: 2024-10-11
- Subjects: Sediments (Geology) , Phosphorus , Sedimentation and deposition , Ecosystem services Law and legislation South Africa , Arid regions South Africa
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466860 , vital:76793 , DOI https://doi.org/10.21504/10962/466860
- Description: A key function of floodplain wetlands systems is their ability to remove and store sediments and associated particulates (such as nutrients, organic carbon, and contaminants) from water, thus improving water quality for downstream ecosystems and water users. Increases in sediment and nutrient inputs to drainage networks pose a serious challenge to integrated resource management. These issues can be partly mitigated through natural buffering solutions along drainage networks, such as preserving essential wetland systems like floodplains. However, their trapping efficiency and storage timescales are uncertain. Although a large body of international knowledge and literature has advanced our understanding of river-floodplain systems and the ecosystem services that they provide, the factors determining their likelihood and effectiveness in supplying those regulatory ecosystem services have not been extensively and scientifically tested in floodplain systems in South Africa. This research aimed to describe and quantify the regulatory ecosystem services related to sediment and phosphorus buffering dynamics of two meandering floodplain systems in the Eastern Cape, South Africa. The study examined the geomorphology, sedimentology, and historical rates of sediment and associated phosphorus accumulation and release in the two floodplain systems. These systems varied in their morphometric features, size, catchment location, and predominant land use, providing a diverse range of characteristics. A comparative analysis was conducted between the two systems to understand the influence of local and catchment-scale factors. Time-averaged suspended sediment samples from the two wetlands were used to compare suspended sediment and associated total phosphorous fluxes over annual scales. Although both floodplains were net depositional during the study period, contemporary suspended sediment mass balance calculations suggested that the relatively larger Minnehaha floodplain system (~1.5 km²) situated in a significantly smaller catchment (~40 km²) had notably higher sediment and associated phosphorus trapping efficiencies of 44 % and 49 % respectively, compared to 16 % and 8 % for the relatively small Gatberg floodplain system (~0.3 km2) situated in a much larger catchment (~135 km²). This variability is attributed to the interaction between annual rainfall regimes, sediment supply, sediment composition, relative wetland size to catchment area and wetland geomorphic character. To test the hypothesis that the suspended sediments and associated total phosphorus were retained by the adjacent floodplain system and to determine which parts of the two floodplains were most effective for retaining suspended sediments and phosphorus, concurrent measurements of sediment accretion were made at 6 sites in different geomorphic features in each of the floodplains. This was achieved using Cesium-137 and Lead-210 (Hereinafter referred to as ¹³⁷Cs and ²¹⁰Pb) dating techniques. In-field observations suggested that all geomorphic units are still active and are frequently inundated during overbank flood flows. The average overbank sediment deposition and total phosphorus accumulation rates were 9376.9 g-sediment m¯² yr¯¹, 0.8 g-TP m¯² yr¯¹ for the Gatberg floodplain and 11802.8 g-sediment m¯² yr¯¹, 1.0 g-TP m¯² yr¯¹ for the Minnehaha floodplain. Deposition rates were temporally and spatially highly variable and dependent on the sediment supply, microtopographic relief, sinuosity, distance from the channel, the mode of inundation, and the extent of retention pondage. Overall, high average deposition rates were associated closest to the channel within the proximal floodplain zone (9712.1 g-sediment m¯² yr¯¹, 1.0 g-TP m¯² yr¯¹ for the Gatberg floodplain; 13541.1 g-sediment m¯² yr¯¹, 1.0 g-TP m¯² yr¯¹ for the Minnehaha floodplain) where the highest D₅₀ particle sizes (25.4 μm for the Gatberg and 32.8 μm for the Minnehaha) and percentage sand fractions (15 % and 21 %, respectively) were found. This may reflect the coarse nature of the sediment and the frequent connectivity to the channel, suggesting rapid accumulation is linked to a larger particle size which was deposited more readily in this zone. In the Gatberg system, the backswamp zone had one of the highest sedimentation rates and second highest phosphorus accumulation rates (13806.8 g-sediment m¯² yr¯¹, 0.9 g-TP m¯² yr¯¹). This was attributed to the additional coarse sediment inputs from the uncapped gravel forestry road that runs adjacent to the floodplain margin. In contrast, the backswamp zone within the Minnehaha River floodplain system had the lowest sedimentation rates (2005.9 g-sediment m¯² yr¯¹, 0.1 g-TP m¯² yr¯¹, which is what would be expected for the zone furthest away from the channel. In both floodplains, oxbows were important fine-sediment and phosphorus retention features (7126.0 g-sediment m¯² yr¯¹, 0.6 g-TP m¯² yr¯¹ for the Gatberg floodplain; 10101.0 g-sediment m¯² yr¯¹, 1.1 g-TP m¯² yr¯¹). Phosphorus distribution patterns were mainly attributed to variations in organic matter content and iron concentrations in fine-grained sediment deposits, while particle size distributions were less important. Using a mass balance approach the trapping efficiencies of the two floodplain systems were estimated. The average trapping efficiency for the Gatberg River floodplain accounts for 16 % of the suspended sediment yield (1317.5 tonnes-sediment yr¯¹) and 8 % of the suspended sediment-associated total phosphorus yield (0.093 tonnes-TP yr¯¹). Deposition on the Minnehaha floodplain accounts for an average of 44 % (1073.6 tonnes-sediment yr¯¹) and 49 % of the suspended sediment-associated total phosphorus yield (0.098 tonnes-TP yr¯¹). Within the Gatberg and Minnehaha River floodplain systems, the sediment sinks (oxbow and backswamp geomorphic zones) accounted for 13 % and 6 % (1070.6 tonnes-sediment yr¯¹ and 0.069 tonnes-TP yr¯¹); and 28 % and 33 % (683.2 tonnes-sediment yr¯¹ and 0.066 tonnes-TP yr¯¹), respectively, of the mean proportion of the total sediment and associated phosphorus yield. The zone of potential exchange (the proximal floodplain geomorphic zone) within the Gatberg floodplain system was calculated to trap 3 % (247.1 tonnes-yr¯¹) of the mean proportion of the total sediment yield and 2 % (0.023-tonnes yr¯¹) of the mean proportion of the total associated-phosphorus yield. Within the Minnehaha floodplain, this zone was estimated to trap 16 % (390.4 tonnes-sediment yr¯¹ and 0.032 tonnes-TP yr¯¹) of the mean proportion of both the total sediment and associated total phosphorus yield. These results indicate the importance of the distal floodplain reaches and oxbows as sediment and phosphorus storage hotspots. While floodplains mainly result from the accumulation of sediment, they're often modified and altered by erosion processes. Channel erosion and avulsions (e.g. meander bend cutoff events) are natural dynamic processes and form two of the principal processes of meandering river migration. During two wet seasons, both Gatberg and Minnehaha River floodplain areas experienced a mix of deposition and erosion, with slightly higher erosion observed in the Gatberg River reach. Channel bed scouring was prevalent in most cross-sections, suggesting limited sediment accumulation within the main channel beds. Volumetric estimates of sediment loss from meander migration were calculated by analysing cross-sectional data from 2019 and 2021 surveys to determine median and maximum eroded volumes, which were then converted to mass and scaled to tonnes per year for each river's eroded meander bends. The eroded sediment volumes were estimated as 520 tonnes yr¯¹ for the Gatberg and 360 tonnes yr¯¹ for the Minnehaha. The time sequence analysis using historical aerial images (between 1958, 1966, 1993, and 2015) revealed a few channel planform changes due to meander bend cutoff events in both river reaches. These events influence river morphology, increasing local channel slope, reducing sinuosity, and limiting floodplain access while impacting sediment and phosphorus flux. In the Gatberg system, changes in land use, such as increased road density from commercial forestry activities, likely drove channel straightening to accommodate higher sediment and bed loads. In the Minnehaha system, agricultural practices and livestock tracks likely increased sediment loads and hillslope-channel connectivity, driving channel changes. The results from the geochronology of two nested oxbows on the Gatberg floodplain estimated lateral migration rates of ~0.03 m yr¯¹. The floodplain reworking rates of the Gatberg River floodplain are low compared to other systems in humid regions around the world, although, the Gatberg system compares well with migration rates of rivers in dryland regions. This study highlights the potential for floodplains undergoing regular flooding to be effective natural buffers along the sediment and phosphorus cascade in dryland landscapes. It enhances our comprehension of how sediment accumulates over time on floodplains within South African river systems, shedding light on both spatial and temporal patterns. These insights can contribute to better methodologies for evaluating the services provided by floodplain wetlands. These results can inform management decisions by offering a deeper understanding and allowing for the quantification of the cost-benefit of floodplain restoration and preservation actions in South Africa. , Thesis (PhD) -- Faculty of Science, Faculty of Science, Geography, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Schlegel, Philippa Kirsten
- Date: 2024-10-11
- Subjects: Sediments (Geology) , Phosphorus , Sedimentation and deposition , Ecosystem services Law and legislation South Africa , Arid regions South Africa
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466860 , vital:76793 , DOI https://doi.org/10.21504/10962/466860
- Description: A key function of floodplain wetlands systems is their ability to remove and store sediments and associated particulates (such as nutrients, organic carbon, and contaminants) from water, thus improving water quality for downstream ecosystems and water users. Increases in sediment and nutrient inputs to drainage networks pose a serious challenge to integrated resource management. These issues can be partly mitigated through natural buffering solutions along drainage networks, such as preserving essential wetland systems like floodplains. However, their trapping efficiency and storage timescales are uncertain. Although a large body of international knowledge and literature has advanced our understanding of river-floodplain systems and the ecosystem services that they provide, the factors determining their likelihood and effectiveness in supplying those regulatory ecosystem services have not been extensively and scientifically tested in floodplain systems in South Africa. This research aimed to describe and quantify the regulatory ecosystem services related to sediment and phosphorus buffering dynamics of two meandering floodplain systems in the Eastern Cape, South Africa. The study examined the geomorphology, sedimentology, and historical rates of sediment and associated phosphorus accumulation and release in the two floodplain systems. These systems varied in their morphometric features, size, catchment location, and predominant land use, providing a diverse range of characteristics. A comparative analysis was conducted between the two systems to understand the influence of local and catchment-scale factors. Time-averaged suspended sediment samples from the two wetlands were used to compare suspended sediment and associated total phosphorous fluxes over annual scales. Although both floodplains were net depositional during the study period, contemporary suspended sediment mass balance calculations suggested that the relatively larger Minnehaha floodplain system (~1.5 km²) situated in a significantly smaller catchment (~40 km²) had notably higher sediment and associated phosphorus trapping efficiencies of 44 % and 49 % respectively, compared to 16 % and 8 % for the relatively small Gatberg floodplain system (~0.3 km2) situated in a much larger catchment (~135 km²). This variability is attributed to the interaction between annual rainfall regimes, sediment supply, sediment composition, relative wetland size to catchment area and wetland geomorphic character. To test the hypothesis that the suspended sediments and associated total phosphorus were retained by the adjacent floodplain system and to determine which parts of the two floodplains were most effective for retaining suspended sediments and phosphorus, concurrent measurements of sediment accretion were made at 6 sites in different geomorphic features in each of the floodplains. This was achieved using Cesium-137 and Lead-210 (Hereinafter referred to as ¹³⁷Cs and ²¹⁰Pb) dating techniques. In-field observations suggested that all geomorphic units are still active and are frequently inundated during overbank flood flows. The average overbank sediment deposition and total phosphorus accumulation rates were 9376.9 g-sediment m¯² yr¯¹, 0.8 g-TP m¯² yr¯¹ for the Gatberg floodplain and 11802.8 g-sediment m¯² yr¯¹, 1.0 g-TP m¯² yr¯¹ for the Minnehaha floodplain. Deposition rates were temporally and spatially highly variable and dependent on the sediment supply, microtopographic relief, sinuosity, distance from the channel, the mode of inundation, and the extent of retention pondage. Overall, high average deposition rates were associated closest to the channel within the proximal floodplain zone (9712.1 g-sediment m¯² yr¯¹, 1.0 g-TP m¯² yr¯¹ for the Gatberg floodplain; 13541.1 g-sediment m¯² yr¯¹, 1.0 g-TP m¯² yr¯¹ for the Minnehaha floodplain) where the highest D₅₀ particle sizes (25.4 μm for the Gatberg and 32.8 μm for the Minnehaha) and percentage sand fractions (15 % and 21 %, respectively) were found. This may reflect the coarse nature of the sediment and the frequent connectivity to the channel, suggesting rapid accumulation is linked to a larger particle size which was deposited more readily in this zone. In the Gatberg system, the backswamp zone had one of the highest sedimentation rates and second highest phosphorus accumulation rates (13806.8 g-sediment m¯² yr¯¹, 0.9 g-TP m¯² yr¯¹). This was attributed to the additional coarse sediment inputs from the uncapped gravel forestry road that runs adjacent to the floodplain margin. In contrast, the backswamp zone within the Minnehaha River floodplain system had the lowest sedimentation rates (2005.9 g-sediment m¯² yr¯¹, 0.1 g-TP m¯² yr¯¹, which is what would be expected for the zone furthest away from the channel. In both floodplains, oxbows were important fine-sediment and phosphorus retention features (7126.0 g-sediment m¯² yr¯¹, 0.6 g-TP m¯² yr¯¹ for the Gatberg floodplain; 10101.0 g-sediment m¯² yr¯¹, 1.1 g-TP m¯² yr¯¹). Phosphorus distribution patterns were mainly attributed to variations in organic matter content and iron concentrations in fine-grained sediment deposits, while particle size distributions were less important. Using a mass balance approach the trapping efficiencies of the two floodplain systems were estimated. The average trapping efficiency for the Gatberg River floodplain accounts for 16 % of the suspended sediment yield (1317.5 tonnes-sediment yr¯¹) and 8 % of the suspended sediment-associated total phosphorus yield (0.093 tonnes-TP yr¯¹). Deposition on the Minnehaha floodplain accounts for an average of 44 % (1073.6 tonnes-sediment yr¯¹) and 49 % of the suspended sediment-associated total phosphorus yield (0.098 tonnes-TP yr¯¹). Within the Gatberg and Minnehaha River floodplain systems, the sediment sinks (oxbow and backswamp geomorphic zones) accounted for 13 % and 6 % (1070.6 tonnes-sediment yr¯¹ and 0.069 tonnes-TP yr¯¹); and 28 % and 33 % (683.2 tonnes-sediment yr¯¹ and 0.066 tonnes-TP yr¯¹), respectively, of the mean proportion of the total sediment and associated phosphorus yield. The zone of potential exchange (the proximal floodplain geomorphic zone) within the Gatberg floodplain system was calculated to trap 3 % (247.1 tonnes-yr¯¹) of the mean proportion of the total sediment yield and 2 % (0.023-tonnes yr¯¹) of the mean proportion of the total associated-phosphorus yield. Within the Minnehaha floodplain, this zone was estimated to trap 16 % (390.4 tonnes-sediment yr¯¹ and 0.032 tonnes-TP yr¯¹) of the mean proportion of both the total sediment and associated total phosphorus yield. These results indicate the importance of the distal floodplain reaches and oxbows as sediment and phosphorus storage hotspots. While floodplains mainly result from the accumulation of sediment, they're often modified and altered by erosion processes. Channel erosion and avulsions (e.g. meander bend cutoff events) are natural dynamic processes and form two of the principal processes of meandering river migration. During two wet seasons, both Gatberg and Minnehaha River floodplain areas experienced a mix of deposition and erosion, with slightly higher erosion observed in the Gatberg River reach. Channel bed scouring was prevalent in most cross-sections, suggesting limited sediment accumulation within the main channel beds. Volumetric estimates of sediment loss from meander migration were calculated by analysing cross-sectional data from 2019 and 2021 surveys to determine median and maximum eroded volumes, which were then converted to mass and scaled to tonnes per year for each river's eroded meander bends. The eroded sediment volumes were estimated as 520 tonnes yr¯¹ for the Gatberg and 360 tonnes yr¯¹ for the Minnehaha. The time sequence analysis using historical aerial images (between 1958, 1966, 1993, and 2015) revealed a few channel planform changes due to meander bend cutoff events in both river reaches. These events influence river morphology, increasing local channel slope, reducing sinuosity, and limiting floodplain access while impacting sediment and phosphorus flux. In the Gatberg system, changes in land use, such as increased road density from commercial forestry activities, likely drove channel straightening to accommodate higher sediment and bed loads. In the Minnehaha system, agricultural practices and livestock tracks likely increased sediment loads and hillslope-channel connectivity, driving channel changes. The results from the geochronology of two nested oxbows on the Gatberg floodplain estimated lateral migration rates of ~0.03 m yr¯¹. The floodplain reworking rates of the Gatberg River floodplain are low compared to other systems in humid regions around the world, although, the Gatberg system compares well with migration rates of rivers in dryland regions. This study highlights the potential for floodplains undergoing regular flooding to be effective natural buffers along the sediment and phosphorus cascade in dryland landscapes. It enhances our comprehension of how sediment accumulates over time on floodplains within South African river systems, shedding light on both spatial and temporal patterns. These insights can contribute to better methodologies for evaluating the services provided by floodplain wetlands. These results can inform management decisions by offering a deeper understanding and allowing for the quantification of the cost-benefit of floodplain restoration and preservation actions in South Africa. , Thesis (PhD) -- Faculty of Science, Faculty of Science, Geography, 2024
- Full Text:
- Date Issued: 2024-10-11
Selective and sensitive electrochemical detection of the Human Epidermal Growth Receptor 2 breast cancer biomarker, using Co (II) phthalocyanine-nanoparticle based platforms
- Centane, Sixolile Sibongiseni
- Authors: Centane, Sixolile Sibongiseni
- Date: 2024-10-11
- Subjects: Electrochemical sensors , HER-2 protein , Breast Cancer , Biochemical markers , Phthalocyanines , Nanoparticles
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466569 , vital:76753 , DOI https://doi.org/10.21504/10962/466570
- Description: Breast cancer is the world’s leading cause of cancer related deaths in women worldwide. The main reason lies in its late detection, mostly in the metastatic stage resulting in poor after-therapy prognosis, despite advances in methods of diagnosis and therapy. The reason for late-stage detection, is because breast cancer like any other cancers is asymptomatic in its early stages. Significant and characterizable features present in the later stages. Furthermore, conventional methods for breast cancer detection are more useful in the identification of the phenotypic features of cancer cells that arise at a later stage of the disease. Another issue with conventional methods where cancer diagnosis is concerned is that they tend to be specialist-dependent, time consuming and costly. Thus, easy, fast and inexpensive detection methods need to be developed urgently. Biomarker-based cancer diagnosis has emerged as one of the most promising strategies for early diagnosis, monitoring disease progression, and subsequent cancer treatment. This thesis focuses on the design and development of novel electrochemical biosensor platforms towards the low cost, efficient, sensitive and simple detection of early-stage breast cancer biomarker, human epidermal growth factor 2 (HER2). The electrochemical method is preferred because of its moderate cost, rapid response, ease of operation, readily quantifiable signal as well as high sensitivity and selectivity with lower detection limits. This thesis reports on two strategies towards signal amplification and sensitive detection of HER2, namely signal based amplification and target-based amplification. The former focuses on electrode or transducer modification techniques for improved signal to noise ratio. In which case; novel nanocomposites of phthalocyanines, graphene quantum dots, gold nanoparticles and cerium oxide nanoparticles are used for electrode modification for signal amplification and biorecognition element immobilization. The biorecognition elements of choice, are an aptamer and antibody known to be specific to the HER2 antigen for an enhanced sensor sensitivity and specificity. The second strategy focuses on increasing the number of detectable targets on the electrode surface towards enhanced sensitivity, precision and sensor accuracy. In which case; the performance of the aptamer and the antibody as recognition elements was explored. Furthermore, the effect of arrangement of these recognition elements on the electrode surface is investigated and reported upon. The strategies covered in this thesis are expected to result in novel biosensor platforms that can detect the HER2 biomarker with high precision, reproducibility, sensitivity and stability; towards low cost and effective early-stage breast cancer diagnostic tools. , Thesis (PhD) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Centane, Sixolile Sibongiseni
- Date: 2024-10-11
- Subjects: Electrochemical sensors , HER-2 protein , Breast Cancer , Biochemical markers , Phthalocyanines , Nanoparticles
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466569 , vital:76753 , DOI https://doi.org/10.21504/10962/466570
- Description: Breast cancer is the world’s leading cause of cancer related deaths in women worldwide. The main reason lies in its late detection, mostly in the metastatic stage resulting in poor after-therapy prognosis, despite advances in methods of diagnosis and therapy. The reason for late-stage detection, is because breast cancer like any other cancers is asymptomatic in its early stages. Significant and characterizable features present in the later stages. Furthermore, conventional methods for breast cancer detection are more useful in the identification of the phenotypic features of cancer cells that arise at a later stage of the disease. Another issue with conventional methods where cancer diagnosis is concerned is that they tend to be specialist-dependent, time consuming and costly. Thus, easy, fast and inexpensive detection methods need to be developed urgently. Biomarker-based cancer diagnosis has emerged as one of the most promising strategies for early diagnosis, monitoring disease progression, and subsequent cancer treatment. This thesis focuses on the design and development of novel electrochemical biosensor platforms towards the low cost, efficient, sensitive and simple detection of early-stage breast cancer biomarker, human epidermal growth factor 2 (HER2). The electrochemical method is preferred because of its moderate cost, rapid response, ease of operation, readily quantifiable signal as well as high sensitivity and selectivity with lower detection limits. This thesis reports on two strategies towards signal amplification and sensitive detection of HER2, namely signal based amplification and target-based amplification. The former focuses on electrode or transducer modification techniques for improved signal to noise ratio. In which case; novel nanocomposites of phthalocyanines, graphene quantum dots, gold nanoparticles and cerium oxide nanoparticles are used for electrode modification for signal amplification and biorecognition element immobilization. The biorecognition elements of choice, are an aptamer and antibody known to be specific to the HER2 antigen for an enhanced sensor sensitivity and specificity. The second strategy focuses on increasing the number of detectable targets on the electrode surface towards enhanced sensitivity, precision and sensor accuracy. In which case; the performance of the aptamer and the antibody as recognition elements was explored. Furthermore, the effect of arrangement of these recognition elements on the electrode surface is investigated and reported upon. The strategies covered in this thesis are expected to result in novel biosensor platforms that can detect the HER2 biomarker with high precision, reproducibility, sensitivity and stability; towards low cost and effective early-stage breast cancer diagnostic tools. , Thesis (PhD) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
Shaping self through ceramic sculpture: representing anxiety in the rural black queer experience
- Authors: Phaliso, Phila Vuyiseka
- Date: 2024-10-11
- Subjects: Ceramic sculpture 21st century , Ceramic sculpture Social aspects , Sexual minorities, Black Social conditions , Anxiety , Rural conditions
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/466082 , vital:76683
- Description: I am a ceramic sculptor. I make use of clay that I have sourced from Joza, the Makhanda location, and Cofimvaba in a rural area called Magwala. I process this clay and then use it to create a visual and tangible representation of the anxiety I experience as a queer black woman living in South Africa. Unongayindoda is a word that has been used by isiXhosa speaking people in my village to call me ever since I was a child. This is a word that I have chosen to own, in much the same way that some people have chosen to own the word “queer.” My experience of being unongayindoda has had an impact on my mental health, and the process of digging clay, processing it for use and then using it to create my work has become very therapeutic for me. My work’s primary aim is to explore the use of clay as a representative embodiment of anxiety in my work as a rural black queer sculptor who identifies as unongayindoda. The thesis component of my work is a qualitative study informed by autoethnography, practice and art-based research. , Thesis (MA) -- Faculty of Humanities, Fine Art, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Phaliso, Phila Vuyiseka
- Date: 2024-10-11
- Subjects: Ceramic sculpture 21st century , Ceramic sculpture Social aspects , Sexual minorities, Black Social conditions , Anxiety , Rural conditions
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/466082 , vital:76683
- Description: I am a ceramic sculptor. I make use of clay that I have sourced from Joza, the Makhanda location, and Cofimvaba in a rural area called Magwala. I process this clay and then use it to create a visual and tangible representation of the anxiety I experience as a queer black woman living in South Africa. Unongayindoda is a word that has been used by isiXhosa speaking people in my village to call me ever since I was a child. This is a word that I have chosen to own, in much the same way that some people have chosen to own the word “queer.” My experience of being unongayindoda has had an impact on my mental health, and the process of digging clay, processing it for use and then using it to create my work has become very therapeutic for me. My work’s primary aim is to explore the use of clay as a representative embodiment of anxiety in my work as a rural black queer sculptor who identifies as unongayindoda. The thesis component of my work is a qualitative study informed by autoethnography, practice and art-based research. , Thesis (MA) -- Faculty of Humanities, Fine Art, 2024
- Full Text:
- Date Issued: 2024-10-11
Singing pretty: investigating female respectability in classical vocal performance in South Africa
- Authors: Van der Walt, Alida
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/466102 , vital:76685
- Description: In this thesis, I consider respectability in classical vocal performance in South Africa by presenting research on six women who hold prominent positions in this field intertwined with my own experiences in this arena. I introduce the context and background to my research across the fields of respectability politics, music studies, and intersectionality before investigating two main modes of gendered bodily respectability that featured in my singer-participants’ lives. These include first extra-bodily technologies in service of respectability, referring to anything that a singer may externally and visibly apply (on)to her body to enhance its physical appeal in specific ways, in line with respectability’s requirements. In thinking through the notion of extra-bodily technologies, I outline via cyborg theory how this first mode of respectability policing operates as an intersectionally oppressive force in my own and my singer-participants’ lives. The second form of bodily discipline emerges in what I call intra-bodily markers of respectability. In developing this term, I demonstrate, based on my singer-participants’ experiences and my own, how the policing of intra-bodily respectability markers may shift our understanding of identity performativity from the discursive realm into the physical. In doing so, I think critically about the importance of language in respectability’s shaping of women’s realities. With little subversive potential found in these themes, I explore the theme of play as a subversive strategy employed by the singers in my study, contrasting the playful subversion with my own mode of ‘serious’ rebellion. Play, with its ambiguous nature rooted in theories of psychology and self-realization, becomes a fundamental aspect of human development, allowing individuals to explore their capabilities and confront societal limitations. I explore the gendered aspects of subversive play in various arenas such as physical appearance, sexuality, musicianship, race, and class, emphasizing and questioning its potential as a political action within the constraints of societal structures. The final part of the thesis explores my own experiences of embodied unbecoming from respectability’s oppressions through vocal performance. Here, I tie together the three strands presented in the body of this thesis through my singing, transgressing body in reference to what I call a feminist musicianship practice as a way of singing beyond respectability. , Thesis (MA) -- Faculty of Humanities, Music and Musicology, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Van der Walt, Alida
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/466102 , vital:76685
- Description: In this thesis, I consider respectability in classical vocal performance in South Africa by presenting research on six women who hold prominent positions in this field intertwined with my own experiences in this arena. I introduce the context and background to my research across the fields of respectability politics, music studies, and intersectionality before investigating two main modes of gendered bodily respectability that featured in my singer-participants’ lives. These include first extra-bodily technologies in service of respectability, referring to anything that a singer may externally and visibly apply (on)to her body to enhance its physical appeal in specific ways, in line with respectability’s requirements. In thinking through the notion of extra-bodily technologies, I outline via cyborg theory how this first mode of respectability policing operates as an intersectionally oppressive force in my own and my singer-participants’ lives. The second form of bodily discipline emerges in what I call intra-bodily markers of respectability. In developing this term, I demonstrate, based on my singer-participants’ experiences and my own, how the policing of intra-bodily respectability markers may shift our understanding of identity performativity from the discursive realm into the physical. In doing so, I think critically about the importance of language in respectability’s shaping of women’s realities. With little subversive potential found in these themes, I explore the theme of play as a subversive strategy employed by the singers in my study, contrasting the playful subversion with my own mode of ‘serious’ rebellion. Play, with its ambiguous nature rooted in theories of psychology and self-realization, becomes a fundamental aspect of human development, allowing individuals to explore their capabilities and confront societal limitations. I explore the gendered aspects of subversive play in various arenas such as physical appearance, sexuality, musicianship, race, and class, emphasizing and questioning its potential as a political action within the constraints of societal structures. The final part of the thesis explores my own experiences of embodied unbecoming from respectability’s oppressions through vocal performance. Here, I tie together the three strands presented in the body of this thesis through my singing, transgressing body in reference to what I call a feminist musicianship practice as a way of singing beyond respectability. , Thesis (MA) -- Faculty of Humanities, Music and Musicology, 2024
- Full Text:
- Date Issued: 2024-10-11
SolarKAT: a solar imaging pipeline for MeerKAT
- Samboco, Victória da Graça Gilberto
- Authors: Samboco, Victória da Graça Gilberto
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465102 , vital:76573
- Description: Solar interference poses a significant challenge in radio interferometric observations, particularly with the increasing sensitivity of modern new-generation telescopes. This thesis presents the SolarKAT pipeline, a novel approach designed to mitigate solar interference in MeerKAT observations. The pipeline incorporates a series of steps, including self-calibration (second generation calibration or 2GC), precise determination of the Sun’s position, phase centre adjustments, creation of region-based masks, deconvolution, prediction, solar model subtraction, and peeling. We applied the SolarKAT pipeline to three datasets that feature the Sun in different conditions (frequency band and angular distance from the Sun to the telescope pointing position). These observations were obtained from three MeerKAT telescope surveys: ThunderKAT, MIGHTEE and LADUMA. We compared the visual images, peak fluxes, flux density, RMS and pixel distribution to evaluate the pipeline. Our results showed a notable reduction in solar interference. This is evidenced by the improved image quality, reduction in RMS and pixel distribution values, and consistent peak flux measurements after applying the pipeline. SolarKAT has not only improved the data quality but also demonstrated to be a valuable tool in producing high-quality solar images, which can be a helpful resource for solar physics and space weather forecasts. This study showcases the potential of the SolarKAT pipeline in enabling high-quality radio interferometric observations, even in the presence of solar interference. Unlike conventional methods that often discard corrupted visibilities (e.g. flagging), our approach focuses on recovering them. Additionally, the SolarKAT pipeline naturally delivers detailed images of the Sun. Our findings contribute to advancing the field of radio interferometry, providing a valuable tool for researchers seeking to enhance the accuracy of their observations and conduct studies in solar physics and space weather. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Samboco, Victória da Graça Gilberto
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465102 , vital:76573
- Description: Solar interference poses a significant challenge in radio interferometric observations, particularly with the increasing sensitivity of modern new-generation telescopes. This thesis presents the SolarKAT pipeline, a novel approach designed to mitigate solar interference in MeerKAT observations. The pipeline incorporates a series of steps, including self-calibration (second generation calibration or 2GC), precise determination of the Sun’s position, phase centre adjustments, creation of region-based masks, deconvolution, prediction, solar model subtraction, and peeling. We applied the SolarKAT pipeline to three datasets that feature the Sun in different conditions (frequency band and angular distance from the Sun to the telescope pointing position). These observations were obtained from three MeerKAT telescope surveys: ThunderKAT, MIGHTEE and LADUMA. We compared the visual images, peak fluxes, flux density, RMS and pixel distribution to evaluate the pipeline. Our results showed a notable reduction in solar interference. This is evidenced by the improved image quality, reduction in RMS and pixel distribution values, and consistent peak flux measurements after applying the pipeline. SolarKAT has not only improved the data quality but also demonstrated to be a valuable tool in producing high-quality solar images, which can be a helpful resource for solar physics and space weather forecasts. This study showcases the potential of the SolarKAT pipeline in enabling high-quality radio interferometric observations, even in the presence of solar interference. Unlike conventional methods that often discard corrupted visibilities (e.g. flagging), our approach focuses on recovering them. Additionally, the SolarKAT pipeline naturally delivers detailed images of the Sun. Our findings contribute to advancing the field of radio interferometry, providing a valuable tool for researchers seeking to enhance the accuracy of their observations and conduct studies in solar physics and space weather. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2024
- Full Text:
- Date Issued: 2024-10-11
South Africa’s financial services trade and trade potential under the African Continental Free Trade Area
- Authors: Gyan, Mawuko
- Date: 2024-10-11
- Subjects: Trade finance , South Africa Commerce , African Continental Free Trade Area , Gravity model of international trade
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/462846 , vital:76340
- Description: This study investigates the nature, importance and prospects for growth of South Africa’s trade in financial services and trade potential under the African Continental Free Trade Area (AfCFTA) Agreement. It does so by identifying and measuring the share, growth performance and some of the characteristics of South Africa’s financial services trade in the aggregate and with selected trading partners and regions. It also computes South Africa’s trade potential in financial and finance-related services trade with selected African trading partners amid the ongoing AfCFTA services trade negotiations, using trade complementarity indices (TCIs). Finally, the study estimates the effect of regional trade agreement participation on bilateral financial services trade involving African economies using a gravity model. The study employs the use of descriptive trade statistics to analyse the share and growth performance of South Africa’s services trade in the aggregate and at the sub-sector level, based on balance of payments (BOP) data for the years 2005 to 2022 from the ITC, UNCTAD and WTO Trade in Services Database. Bilateral trade data from the OECD and WTO BaTIS Database is also used in the analysis of intra-African trade. In order to investigate trade through Mode 3, information on FDI statistics is sourced from recent reports. Through analysing trade complementarity indices (TCIs), the study finds that South Africa has significant potential to increase exports of financial and finance-related services to Mauritius, Ghana and the SADC and non-TFTA regions. South Africa has significant import TCIs with the COMESA and non- TFTA regions as well as Egypt, Tunisia and Kenya. The gravity model estimation reveals that membership in African regional groupings like the AfCFTA, SADC, COMESA and the EAC have no significant positive impact as yet on intra-African financial services trade. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Gyan, Mawuko
- Date: 2024-10-11
- Subjects: Trade finance , South Africa Commerce , African Continental Free Trade Area , Gravity model of international trade
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/462846 , vital:76340
- Description: This study investigates the nature, importance and prospects for growth of South Africa’s trade in financial services and trade potential under the African Continental Free Trade Area (AfCFTA) Agreement. It does so by identifying and measuring the share, growth performance and some of the characteristics of South Africa’s financial services trade in the aggregate and with selected trading partners and regions. It also computes South Africa’s trade potential in financial and finance-related services trade with selected African trading partners amid the ongoing AfCFTA services trade negotiations, using trade complementarity indices (TCIs). Finally, the study estimates the effect of regional trade agreement participation on bilateral financial services trade involving African economies using a gravity model. The study employs the use of descriptive trade statistics to analyse the share and growth performance of South Africa’s services trade in the aggregate and at the sub-sector level, based on balance of payments (BOP) data for the years 2005 to 2022 from the ITC, UNCTAD and WTO Trade in Services Database. Bilateral trade data from the OECD and WTO BaTIS Database is also used in the analysis of intra-African trade. In order to investigate trade through Mode 3, information on FDI statistics is sourced from recent reports. Through analysing trade complementarity indices (TCIs), the study finds that South Africa has significant potential to increase exports of financial and finance-related services to Mauritius, Ghana and the SADC and non-TFTA regions. South Africa has significant import TCIs with the COMESA and non- TFTA regions as well as Egypt, Tunisia and Kenya. The gravity model estimation reveals that membership in African regional groupings like the AfCFTA, SADC, COMESA and the EAC have no significant positive impact as yet on intra-African financial services trade. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
- Full Text:
- Date Issued: 2024-10-11
Spatial pattern analysis of thicket expansion in a semi-arid savanna
- Authors: Putzier, Rachel Rayne
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464484 , vital:76515
- Description: Woody thickening has negative economic and ecological impacts in savannas globally. While the increase of savanna trees as a form of bush encroachment has been well studied, less is known about the increase of thicket species in savannas, which is an important phenomenon resulting in the formation of closed-canopy clumps which may exclude the grass layer over time. The early stage of thicket expansion is often initiated by a nucleating savanna species which facilitates the establishment of woody thicket pioneer species, and as the thicket clump formation expands, bush clumps increase in dominance, thereby increasing the frequency of competitive interactions and leading to a possible switch from facilitative to competitive interactions. Spatial point pattern analysis provides a useful tool to elucidate these underlying patterns and ecological processes. I used high resolution LiDAR data combined with spatial point pattern analysis to understand tree-tree interactions in a semi-arid savanna in the Eastern Cape Province of South Africa. I conducted a cluster analysis based on vegetation structural variables to distinguish different stages of woody plant encroachment from open savanna to closed canopy thicket. Using the canopy height model, I quantified the change in the grass height from open savanna to closed canopy thicket clumps as an indicator of a possible biome shift. Additionally, I used spatial point pattern analyses to investigate the effect of thicket clump formation on the composition of savanna and thicket species, the overall patterns of trees, and the associations of small thicket species with large Vachellia karroo trees, which serve as clump initiators. Finally, I examined the mortality of savanna trees across increasing stages of thicket expansion using second order spatial statistics, namely the Mark- and Pair-Correlation Functions. Results confirmed that three vegetation states, influenced by elevation, are present at the study site, representing open canopy savanna (early-stage thicket encroachment), encroached savanna with low thicket dominance (intermediate-stage thicket encroachment), and highly encroached with dominant thicket clumps (late-stage thicket encroachment). These stages showed increasing tree height, canopy cover and canopy height density, as well as decreased (but not completely absent grass layer) as thicket encroachment progresses. Spatial point pattern analysis showed, as predicted, that there was an overall aggregation of trees at small-scales within early thicket clump formation, from which I inferred that facilitative relationships may exist between trees. Contrary to my predictions, at later stages of thicket clump formation I found dominant independent patterns between savanna adults and juvenile thicket species, which may result from a combination of facilitative and competitive effects. Lastly, as expected, I found that the density of V. karroo mortality increased as thicket encroachment increased, with an overall random spatial pattern of dead V. karroo across encroachment stages. As predicted, tree mortality was randomly distributed in space in the open savanna state, and as thicket clump formation increases, tree competitive mortality became more evident, as well as decreased tree performance. Overall, the study highlights the interplay between facilitation and competition in semiarid savanna where thicket clumps are expanding. Intervention strategies are suggested to target areas of intermediate thicket clump formation, as these areas provide an opportunity to remove V. karroo before the nucleation process has enabled the establishment and increase of thicket species and to ensure the grass layer is kept productive. I conclude that the use of remote sensing and LiDAR technology holds a wide range of possibilities for monitoring and managing woody encroachment in savanna systems, however these methods need to be further refined for effective use within African savanna and thicket context, which displays high spatial aggregation making typical segmentation methods difficult. , Thesis (MSc) -- Faculty of Science, Botany, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Putzier, Rachel Rayne
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464484 , vital:76515
- Description: Woody thickening has negative economic and ecological impacts in savannas globally. While the increase of savanna trees as a form of bush encroachment has been well studied, less is known about the increase of thicket species in savannas, which is an important phenomenon resulting in the formation of closed-canopy clumps which may exclude the grass layer over time. The early stage of thicket expansion is often initiated by a nucleating savanna species which facilitates the establishment of woody thicket pioneer species, and as the thicket clump formation expands, bush clumps increase in dominance, thereby increasing the frequency of competitive interactions and leading to a possible switch from facilitative to competitive interactions. Spatial point pattern analysis provides a useful tool to elucidate these underlying patterns and ecological processes. I used high resolution LiDAR data combined with spatial point pattern analysis to understand tree-tree interactions in a semi-arid savanna in the Eastern Cape Province of South Africa. I conducted a cluster analysis based on vegetation structural variables to distinguish different stages of woody plant encroachment from open savanna to closed canopy thicket. Using the canopy height model, I quantified the change in the grass height from open savanna to closed canopy thicket clumps as an indicator of a possible biome shift. Additionally, I used spatial point pattern analyses to investigate the effect of thicket clump formation on the composition of savanna and thicket species, the overall patterns of trees, and the associations of small thicket species with large Vachellia karroo trees, which serve as clump initiators. Finally, I examined the mortality of savanna trees across increasing stages of thicket expansion using second order spatial statistics, namely the Mark- and Pair-Correlation Functions. Results confirmed that three vegetation states, influenced by elevation, are present at the study site, representing open canopy savanna (early-stage thicket encroachment), encroached savanna with low thicket dominance (intermediate-stage thicket encroachment), and highly encroached with dominant thicket clumps (late-stage thicket encroachment). These stages showed increasing tree height, canopy cover and canopy height density, as well as decreased (but not completely absent grass layer) as thicket encroachment progresses. Spatial point pattern analysis showed, as predicted, that there was an overall aggregation of trees at small-scales within early thicket clump formation, from which I inferred that facilitative relationships may exist between trees. Contrary to my predictions, at later stages of thicket clump formation I found dominant independent patterns between savanna adults and juvenile thicket species, which may result from a combination of facilitative and competitive effects. Lastly, as expected, I found that the density of V. karroo mortality increased as thicket encroachment increased, with an overall random spatial pattern of dead V. karroo across encroachment stages. As predicted, tree mortality was randomly distributed in space in the open savanna state, and as thicket clump formation increases, tree competitive mortality became more evident, as well as decreased tree performance. Overall, the study highlights the interplay between facilitation and competition in semiarid savanna where thicket clumps are expanding. Intervention strategies are suggested to target areas of intermediate thicket clump formation, as these areas provide an opportunity to remove V. karroo before the nucleation process has enabled the establishment and increase of thicket species and to ensure the grass layer is kept productive. I conclude that the use of remote sensing and LiDAR technology holds a wide range of possibilities for monitoring and managing woody encroachment in savanna systems, however these methods need to be further refined for effective use within African savanna and thicket context, which displays high spatial aggregation making typical segmentation methods difficult. , Thesis (MSc) -- Faculty of Science, Botany, 2024
- Full Text:
- Date Issued: 2024-10-11
Statistical classification, an application to credit default
- Authors: Sikhakhane, Anele Gcina
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465069 , vital:76570
- Description: Statistical learning has been used in both industry and academia to create credit scoring models. These models are used to predict who might default on their loan repayments, thus minimizing the risk financial institutions face. In this study six traditional and one more recent classifier, namely kNN, LDA, CART, RF, AdaBoost, XGBoost and SynBoost were used to predict who might default on their loans. The data set used in this study was imbalanced thus sampling and performance evaluation techniques were investigated and used to balance the class distribution and assess the classifiers performance. In addition to the standard variables and data set, new variables called synthetic variables and synthetic data sets were produced, investigated and used to predict who might default on their loans. This study found that the synthetic data set had strong predictive power and sampling methods negatively affected the classifiers performance. The best-performing classifier was XGBoost, with an AUC score of 0.7732. , Thesis (MSc) -- Faculty of Science, Statistics, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Sikhakhane, Anele Gcina
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465069 , vital:76570
- Description: Statistical learning has been used in both industry and academia to create credit scoring models. These models are used to predict who might default on their loan repayments, thus minimizing the risk financial institutions face. In this study six traditional and one more recent classifier, namely kNN, LDA, CART, RF, AdaBoost, XGBoost and SynBoost were used to predict who might default on their loans. The data set used in this study was imbalanced thus sampling and performance evaluation techniques were investigated and used to balance the class distribution and assess the classifiers performance. In addition to the standard variables and data set, new variables called synthetic variables and synthetic data sets were produced, investigated and used to predict who might default on their loans. This study found that the synthetic data set had strong predictive power and sampling methods negatively affected the classifiers performance. The best-performing classifier was XGBoost, with an AUC score of 0.7732. , Thesis (MSc) -- Faculty of Science, Statistics, 2024
- Full Text:
- Date Issued: 2024-10-11
Structural dynamic investigation of the mutation-induced resistance mechanisms of Mycobacterium tuberculosis DNA-directed RNA polymerase against Rifampicin
- Authors: Monama, Mokgerwa Zacharia
- Date: 2024-10-11
- Subjects: Mycobacterium tuberculosis , Rifampin , Drug resistance , Molecular dynamics Simulation methods
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466849 , vital:76792 , DOI https://doi.org/10.21504/10962/466849
- Description: Emerging resistant strains of Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB) disease, continue to plague mankind and reduce the efficacies of antitubercular therapies that have been an effective defence against TB for decades. More specifically, mutations located in the β subunit of the multisubunit Mtb RNA replicative machinery, RNA polymerase (RNAP), have been well established as the reason behind resistance to the first-line antitubercular drug rifampicin (RIF), which has resulted in therapeutic failure in several clinical cases. Additionally, elusive details pertaining to the underlying mechanisms associated with RIF resistance due to the presence of Mtb-RNAP-β mutations, have resulted in setbacks in the development of novel and effective drugs that might be able to curb the ongoing threat. Hence, in this investigation, we attempted to resolve the involved Mtb-RNAP structural events at the molecular level to discern potentially important details regarding the nine clinically relevant Mtb-RNAP-β missense mutations under investigation. Hence, for the first time, we conducted an in-silico RIF resistance investigation using the Mtb-RNAP complex. To accomplish the set-out task, we first employed the use of more traditional post-MD analytical approaches such as root mean square deviation, root mean square fluctuation, radius of gyration, center of mass distance analyses, hydrogen bond occupancies, and binding free energy calculations, to conduct a global analysis of the mutated Mtb-RNAP proteins referencing RIF efficacy. Our findings revealed that the mutations may have a perturbation effect resulting in the disruption of essential structural dynamics attributed to the protein’s catalytic functions. This was for instance observed for the βfork loop 2 domain, the β’zinc-binding domain, the β’ trigger loop domain, and the β’jaw domain, which happen to be in line with previously reported experiments detailing changes in RNAP processivity. Complementarily, some of the mutations more specifically perturbed the RIF binding pocket (RIF-BP) which observably led to the reorientation of RIF from the native or active orientation needed to obstruct the processive addition of nucleoside triphosphates to the growing RNA transcript. The mutation-induced repositioning from the active RIF orientation was also reflected through the loss of essential interactions between RIF and the RIF-BP along with the loss of binding affinities captured for a majority of the mutant proteins. In conjunction with traditional analytical approaches, we further employed computational alanine scanning, weighted contact map analyses, and dynamic residue network (DRN) analyses, a novel approach that delineates residue-residue communication pathways through several metrics, to further elucidate how a set of clinically relevant mutations affect Mtb-RNAP function. With that, we were able to observe several key changes in residue importance and interactions that may be instrumental in bringing about RIF resistance and the compensatory conformational changes we observed among the mt systems through global analysis. Furthermore, we identified persistent hubs that may be particularly important in maintaining transcriptional activities in the presence and absence of the investigated mutations and RIF that could serve as potential resistance markers for future therapeutic investigations. We believe these findings will significantly aid future efforts in the discovery of new treatment options with the potential to overcome antitubercular resistance. , Thesis (PhD) -- Faculty of Science, Biochemistry, Microbiology and Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Monama, Mokgerwa Zacharia
- Date: 2024-10-11
- Subjects: Mycobacterium tuberculosis , Rifampin , Drug resistance , Molecular dynamics Simulation methods
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466849 , vital:76792 , DOI https://doi.org/10.21504/10962/466849
- Description: Emerging resistant strains of Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB) disease, continue to plague mankind and reduce the efficacies of antitubercular therapies that have been an effective defence against TB for decades. More specifically, mutations located in the β subunit of the multisubunit Mtb RNA replicative machinery, RNA polymerase (RNAP), have been well established as the reason behind resistance to the first-line antitubercular drug rifampicin (RIF), which has resulted in therapeutic failure in several clinical cases. Additionally, elusive details pertaining to the underlying mechanisms associated with RIF resistance due to the presence of Mtb-RNAP-β mutations, have resulted in setbacks in the development of novel and effective drugs that might be able to curb the ongoing threat. Hence, in this investigation, we attempted to resolve the involved Mtb-RNAP structural events at the molecular level to discern potentially important details regarding the nine clinically relevant Mtb-RNAP-β missense mutations under investigation. Hence, for the first time, we conducted an in-silico RIF resistance investigation using the Mtb-RNAP complex. To accomplish the set-out task, we first employed the use of more traditional post-MD analytical approaches such as root mean square deviation, root mean square fluctuation, radius of gyration, center of mass distance analyses, hydrogen bond occupancies, and binding free energy calculations, to conduct a global analysis of the mutated Mtb-RNAP proteins referencing RIF efficacy. Our findings revealed that the mutations may have a perturbation effect resulting in the disruption of essential structural dynamics attributed to the protein’s catalytic functions. This was for instance observed for the βfork loop 2 domain, the β’zinc-binding domain, the β’ trigger loop domain, and the β’jaw domain, which happen to be in line with previously reported experiments detailing changes in RNAP processivity. Complementarily, some of the mutations more specifically perturbed the RIF binding pocket (RIF-BP) which observably led to the reorientation of RIF from the native or active orientation needed to obstruct the processive addition of nucleoside triphosphates to the growing RNA transcript. The mutation-induced repositioning from the active RIF orientation was also reflected through the loss of essential interactions between RIF and the RIF-BP along with the loss of binding affinities captured for a majority of the mutant proteins. In conjunction with traditional analytical approaches, we further employed computational alanine scanning, weighted contact map analyses, and dynamic residue network (DRN) analyses, a novel approach that delineates residue-residue communication pathways through several metrics, to further elucidate how a set of clinically relevant mutations affect Mtb-RNAP function. With that, we were able to observe several key changes in residue importance and interactions that may be instrumental in bringing about RIF resistance and the compensatory conformational changes we observed among the mt systems through global analysis. Furthermore, we identified persistent hubs that may be particularly important in maintaining transcriptional activities in the presence and absence of the investigated mutations and RIF that could serve as potential resistance markers for future therapeutic investigations. We believe these findings will significantly aid future efforts in the discovery of new treatment options with the potential to overcome antitubercular resistance. , Thesis (PhD) -- Faculty of Science, Biochemistry, Microbiology and Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
Students' perception of pre-exposure prophylaxis as a prevention strategy for reducing HIV/AIDS incidences at Rhodes University
- Authors: Lepelesana, Mamorena Sylvia
- Date: 2024-10-11
- Subjects: Pre-exposure prophylaxis , HIV infections , AIDS (Disease) , College students Attitudes , Stigma (Social psychology) , Rhodes University
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/466150 , vital:76701
- Description: South Africa has the largest number of people living with HIV/AIDS compared to the rest of the world, with young people most at risk. The World Health Organisation (WHO) recommends the use of Pre-Exposure Prophylaxis (PrEP) in key populations at a higher risk of exposure to HIV/AIDS. The HIV/AIDS pandemic remains a pressing issue among higher education institutions, with a need for a comprehensive understanding of barriers and facilitators associated with the use of PrEP. The Higher Education AIDS (HEAIDS) plays a pivotal role in the mitigation of the spread of HIV/AIDS in Higher Education Institutions (HEIs). In this study, Rhodes University serves as a focal point for exploring PrEP implementation and acceptance. This qualitative study examines Rhodes University students' PrEP knowledge, perception, practice, and roll-out preference. More evidence is required to measure progress among students. A study was conducted involving sixteen (16) in-depth semi-structured interviews with students and health care workers, as well as a focus group consisting of three (3) students aged between 20-60 years. This study used the Socio-Ecological Model and Health Belief Model as theoretical frameworks. Participants in the study identified both the barriers and the facilitators to the use of PrEP. The findings show that there is a lack of knowledge and low perception among students about PrEP. The study found that lack of knowledge was the source of the stigma and misconception about PrEP. Most participants expressed the need for more information to differentiate between the ARVs in PrEP and the ARV medication for HIV-positive people. However, they further expressed a willingness to embrace PrEP if they had information about it. The study highlights that the use of PrEP is linked to individual and environmental factors, which are crucial for PrEP roll-out. These factors include access to PrEP in a friendly manner, supportive family and friends, and the reduction of stigma and misconception. Therefore, when addressed, the said factors can foster the use of PrEP and mitigate barriers. For students to fully realise the benefits of HIV/AIDS prevention strategies like PrEP, there is a need for informed educational efforts. A well-informed student body is important for the successful adoption and use of PrEP. The findings suggest that the health care workers were knowledgeable and conscious about the use of PrEP. However, there were inconsistencies in the information provided by the health care workers regarding the recommended period for taking PrEP before testing again and taking the three-month course. The inconsistencies raise questions regarding the accuracy and reliability of the information provided. , Thesis (MSocSci) -- Faculty of Humanities, Sociology, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Lepelesana, Mamorena Sylvia
- Date: 2024-10-11
- Subjects: Pre-exposure prophylaxis , HIV infections , AIDS (Disease) , College students Attitudes , Stigma (Social psychology) , Rhodes University
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/466150 , vital:76701
- Description: South Africa has the largest number of people living with HIV/AIDS compared to the rest of the world, with young people most at risk. The World Health Organisation (WHO) recommends the use of Pre-Exposure Prophylaxis (PrEP) in key populations at a higher risk of exposure to HIV/AIDS. The HIV/AIDS pandemic remains a pressing issue among higher education institutions, with a need for a comprehensive understanding of barriers and facilitators associated with the use of PrEP. The Higher Education AIDS (HEAIDS) plays a pivotal role in the mitigation of the spread of HIV/AIDS in Higher Education Institutions (HEIs). In this study, Rhodes University serves as a focal point for exploring PrEP implementation and acceptance. This qualitative study examines Rhodes University students' PrEP knowledge, perception, practice, and roll-out preference. More evidence is required to measure progress among students. A study was conducted involving sixteen (16) in-depth semi-structured interviews with students and health care workers, as well as a focus group consisting of three (3) students aged between 20-60 years. This study used the Socio-Ecological Model and Health Belief Model as theoretical frameworks. Participants in the study identified both the barriers and the facilitators to the use of PrEP. The findings show that there is a lack of knowledge and low perception among students about PrEP. The study found that lack of knowledge was the source of the stigma and misconception about PrEP. Most participants expressed the need for more information to differentiate between the ARVs in PrEP and the ARV medication for HIV-positive people. However, they further expressed a willingness to embrace PrEP if they had information about it. The study highlights that the use of PrEP is linked to individual and environmental factors, which are crucial for PrEP roll-out. These factors include access to PrEP in a friendly manner, supportive family and friends, and the reduction of stigma and misconception. Therefore, when addressed, the said factors can foster the use of PrEP and mitigate barriers. For students to fully realise the benefits of HIV/AIDS prevention strategies like PrEP, there is a need for informed educational efforts. A well-informed student body is important for the successful adoption and use of PrEP. The findings suggest that the health care workers were knowledgeable and conscious about the use of PrEP. However, there were inconsistencies in the information provided by the health care workers regarding the recommended period for taking PrEP before testing again and taking the three-month course. The inconsistencies raise questions regarding the accuracy and reliability of the information provided. , Thesis (MSocSci) -- Faculty of Humanities, Sociology, 2024
- Full Text:
- Date Issued: 2024-10-11
Suspicious activity reports: Enhancing the detection of terrorist financing and suspicious transactions in migrant remittances
- Authors: Mbiva, Stanley Munamato
- Date: 2024-10-11
- Subjects: Migrant remittances , Terrorism financing , Machine learning , Outliers (Statistics) , Anomaly detection (Computer security) , Unsupervised learning
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465058 , vital:76569
- Description: Migrant remittances have become an important factor in poverty alleviation and microeconomic development in low-income nations. Global migrant remittances are expected to exceed US $630 billion by 2023, according to the World Bank. In addition to offering an alternate source of income that supplements the recipient’s household earnings, they are less likely to be affected by global economic downturns, ensuring stability and a consistent stream of revenue. However, the ease of global migrant remittance financial transfers has attracted the risk of being abused by terrorist organizations to quickly move and conceal operating cash, hence facilitating terrorist financing. This study aims to develop an unsupervised machine-learning model capable of detecting suspicious financial transactions associated with terrorist financing in migrant remittances. The data used in this study came from a World Bank survey of migrant remitters in Belgium. To understand the natural structures and grouping in the dataset, agglomerative hierarchical clustering and k-prototype clustering techniques were employed. This established the number of clusters present in the dataset making it possible to compare individual migrant remittances in the dataset with their peers. A Structural Equation Model (SEM) and an Local Outlier Factor - Isolation Forest (LOF-IF) algorithm were applied to analyze and detect suspicious transactions in the dataset. A traditional Rule-Based Method (RBM) was also created as a benchmark algorithm that evaluates model performance. The results show that the SEM model classifies a significantly high number of transactions as suspicious, making it prone to detecting false positives. Finally, the study applied the proposed ensemble outlier detection model to detect suspicious transactions in the same data set. The proposed ensemble model utilized an Isolation Forest (IF) for pruning and a Local Outlier Factor (LOF) to detect local outliers. The model performed exceptionally well, being able to detect over 90% of suspicious transactions in the testing data set during model cross-validation. , Thesis (MSc) -- Faculty of Science, Statistics, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Mbiva, Stanley Munamato
- Date: 2024-10-11
- Subjects: Migrant remittances , Terrorism financing , Machine learning , Outliers (Statistics) , Anomaly detection (Computer security) , Unsupervised learning
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465058 , vital:76569
- Description: Migrant remittances have become an important factor in poverty alleviation and microeconomic development in low-income nations. Global migrant remittances are expected to exceed US $630 billion by 2023, according to the World Bank. In addition to offering an alternate source of income that supplements the recipient’s household earnings, they are less likely to be affected by global economic downturns, ensuring stability and a consistent stream of revenue. However, the ease of global migrant remittance financial transfers has attracted the risk of being abused by terrorist organizations to quickly move and conceal operating cash, hence facilitating terrorist financing. This study aims to develop an unsupervised machine-learning model capable of detecting suspicious financial transactions associated with terrorist financing in migrant remittances. The data used in this study came from a World Bank survey of migrant remitters in Belgium. To understand the natural structures and grouping in the dataset, agglomerative hierarchical clustering and k-prototype clustering techniques were employed. This established the number of clusters present in the dataset making it possible to compare individual migrant remittances in the dataset with their peers. A Structural Equation Model (SEM) and an Local Outlier Factor - Isolation Forest (LOF-IF) algorithm were applied to analyze and detect suspicious transactions in the dataset. A traditional Rule-Based Method (RBM) was also created as a benchmark algorithm that evaluates model performance. The results show that the SEM model classifies a significantly high number of transactions as suspicious, making it prone to detecting false positives. Finally, the study applied the proposed ensemble outlier detection model to detect suspicious transactions in the same data set. The proposed ensemble model utilized an Isolation Forest (IF) for pruning and a Local Outlier Factor (LOF) to detect local outliers. The model performed exceptionally well, being able to detect over 90% of suspicious transactions in the testing data set during model cross-validation. , Thesis (MSc) -- Faculty of Science, Statistics, 2024
- Full Text:
- Date Issued: 2024-10-11
Synthesis and biological evaluation of simple carboxylated chalcone and aurone derivatives
- Authors: Shauri, Thierry Lwanzo
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464576 , vital:76523
- Description: Restricted access. Expected release in 2026. , Thesis (MSc) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Shauri, Thierry Lwanzo
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464576 , vital:76523
- Description: Restricted access. Expected release in 2026. , Thesis (MSc) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11