Une analyse critique de deux adaptations filmiques de Les Liaisons dangereuses de Pierre Choderlos de Laclos
- Authors: Naumann, Tyler
- Date: 2021-10-29
- Subjects: Film adaptations History and criticism , Laclos, Choderlos de, 1741-1803. Liaisons dangereuses Criticism and interpretation , Liaisons dangereuses (Motion picture) History and criticism , French fiction 18th century History and criticism , Semiotics and motion pictures , Translating and interpreting in motion pictures , Continuum of proximity
- Language: French
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190284 , vital:44980
- Description: Film adaptation has been practised since the emergence of cinema in France in the early twentieth century. Theorists have identified, however, that a detailed system of analysis of film adaptations remains lacking and that there is a dearth of detailed case studies. This study adopts the lens of intersemiotic translation and seeks to apply a system of analysis, comprised of a synthesis of three existing systems (Cattrysse, Metz, McFarlane). The semiotic transferal of five key sequences from the source text are analysed in their film adaptations. The source text, Les Liaisons dangereuses by Pierre Choderlos de Laclos, an eighteenth-century epistolary novel focusing on the erotic exploits of two nobles in French high society, was chosen for its challenging nature as a film adaptation. Two film adaptations, that at first glance seem to be at the opposing extremes of film adaptation classification: ‘free’ and ‘close’; have been chosen to firstly, better understand the mechanics of the semiotic transferal process, and secondly, to identify at which points these adaptations are constituted as ‘free’ or ‘close’. Since the domain’s theorisation in the early 1930’s, the fidelity debate has remained omnipresent in the analysis of film adaptation. Even though theorists have tried to move away from the fidelity debate, it remains indispensable when comparing an adaptation with the original text and is a key point of departure when analysing the semiotic transferal between source text and screen. Through the lens of translation, theorists have come to question the binary classifications of film adaptations: ‘free’ and ‘close’. Contemporary theorists suggest that proximity to the source text operates on a continuum rather than as a fixed category. As a result of the multi-layered system of analysis used in this study, it has been concluded that the two film adaptations chosen are both ‘free’ and ‘close’ at varying points. Intersemiotic translation used in comparative film adaptations studies is therefore a useful methodological tool that allows for a more detailed and nuanced analysis and strengthens the case for using a continuum of proximity rather than fixed classifications. , Depuis l’émergence du cinéma en France au début du XXe siècle, il existe des adaptations filmiques. Les théoriciens de ce domaine constatent pourtant le manque d’un système d’analyse détaillé de ces adaptations. En plus, il y a une pénurie de cas d’études détaillés. La présente étude vise à prendre l’optique de la traduction intersémiotique et à appliquer un système d’analyse, qui se compose d’une synthèse de trois systèmes existants (Cattrysse, Metz, McFarlane). Le transfert sémiotique sera analysé de cinq séquences clefs du texte source. Le texte source, Les Liaisons dangereuses de Pierre Choderlos de Laclos, roman épistolaire du XVIIIe siècle qui se focalise sur les conquêtes amoureuses de deux aristocrates, a été choisi pour sa nature stimulante en tant que projet d’adaptation filmique. Nous avons choisi deux adaptations, qui à première vue, semblent être aux extrêmes opposés de classements des adaptations filmiques : ‘approchant’ et ‘libre’, pour découvrir les mécanismes du processus du transfert sémiotique, et en deuxième lieu, pour identifier à quels points ces adaptations seraient ‘approchantes’ ou ‘libres’. Dès la théorisation du domaine au début des années 1930, le débat de la fidélité est resté omniprésent dans les analyses des adaptations filmiques. Comparer une adaptation filmique au texte source est fait, et reste un point de départ essentiel lorsque l’analyse du transfert sémiotique entre le texte source et l’écran s’effectue. À travers l’optique de la traduction intersémiotique, les théoriciens ont remis en question les classifications binaires des adaptations filmiques : ‘approchante’, ‘hybride’, et ‘libre’. Les théoriciens contemporains suggèrent que la proximité du texte source s’opère sur un continuum au lieu d’être précisée dans des classements fixes. Grâce au système à multiples composantes utilisé dans cette étude, il a été conclu que les deux adaptations filmiques choisies sont toutes les deux ‘approchantes’ et ‘libres’ aux points variés. La traduction intersémiotique utilisée dans les études comparatives des adaptations filmiques constitue donc un outil méthodologue indispensable qui permet une analyse détaillée et nuancée, et qui renforce les arguments en faveur de l’emploi d’un continuum de proximité qui contourne le problème d’étiquettes rigides et binaires. , Thesis (MA) -- Faculty of Humanities, French Studies, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Naumann, Tyler
- Date: 2021-10-29
- Subjects: Film adaptations History and criticism , Laclos, Choderlos de, 1741-1803. Liaisons dangereuses Criticism and interpretation , Liaisons dangereuses (Motion picture) History and criticism , French fiction 18th century History and criticism , Semiotics and motion pictures , Translating and interpreting in motion pictures , Continuum of proximity
- Language: French
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190284 , vital:44980
- Description: Film adaptation has been practised since the emergence of cinema in France in the early twentieth century. Theorists have identified, however, that a detailed system of analysis of film adaptations remains lacking and that there is a dearth of detailed case studies. This study adopts the lens of intersemiotic translation and seeks to apply a system of analysis, comprised of a synthesis of three existing systems (Cattrysse, Metz, McFarlane). The semiotic transferal of five key sequences from the source text are analysed in their film adaptations. The source text, Les Liaisons dangereuses by Pierre Choderlos de Laclos, an eighteenth-century epistolary novel focusing on the erotic exploits of two nobles in French high society, was chosen for its challenging nature as a film adaptation. Two film adaptations, that at first glance seem to be at the opposing extremes of film adaptation classification: ‘free’ and ‘close’; have been chosen to firstly, better understand the mechanics of the semiotic transferal process, and secondly, to identify at which points these adaptations are constituted as ‘free’ or ‘close’. Since the domain’s theorisation in the early 1930’s, the fidelity debate has remained omnipresent in the analysis of film adaptation. Even though theorists have tried to move away from the fidelity debate, it remains indispensable when comparing an adaptation with the original text and is a key point of departure when analysing the semiotic transferal between source text and screen. Through the lens of translation, theorists have come to question the binary classifications of film adaptations: ‘free’ and ‘close’. Contemporary theorists suggest that proximity to the source text operates on a continuum rather than as a fixed category. As a result of the multi-layered system of analysis used in this study, it has been concluded that the two film adaptations chosen are both ‘free’ and ‘close’ at varying points. Intersemiotic translation used in comparative film adaptations studies is therefore a useful methodological tool that allows for a more detailed and nuanced analysis and strengthens the case for using a continuum of proximity rather than fixed classifications. , Depuis l’émergence du cinéma en France au début du XXe siècle, il existe des adaptations filmiques. Les théoriciens de ce domaine constatent pourtant le manque d’un système d’analyse détaillé de ces adaptations. En plus, il y a une pénurie de cas d’études détaillés. La présente étude vise à prendre l’optique de la traduction intersémiotique et à appliquer un système d’analyse, qui se compose d’une synthèse de trois systèmes existants (Cattrysse, Metz, McFarlane). Le transfert sémiotique sera analysé de cinq séquences clefs du texte source. Le texte source, Les Liaisons dangereuses de Pierre Choderlos de Laclos, roman épistolaire du XVIIIe siècle qui se focalise sur les conquêtes amoureuses de deux aristocrates, a été choisi pour sa nature stimulante en tant que projet d’adaptation filmique. Nous avons choisi deux adaptations, qui à première vue, semblent être aux extrêmes opposés de classements des adaptations filmiques : ‘approchant’ et ‘libre’, pour découvrir les mécanismes du processus du transfert sémiotique, et en deuxième lieu, pour identifier à quels points ces adaptations seraient ‘approchantes’ ou ‘libres’. Dès la théorisation du domaine au début des années 1930, le débat de la fidélité est resté omniprésent dans les analyses des adaptations filmiques. Comparer une adaptation filmique au texte source est fait, et reste un point de départ essentiel lorsque l’analyse du transfert sémiotique entre le texte source et l’écran s’effectue. À travers l’optique de la traduction intersémiotique, les théoriciens ont remis en question les classifications binaires des adaptations filmiques : ‘approchante’, ‘hybride’, et ‘libre’. Les théoriciens contemporains suggèrent que la proximité du texte source s’opère sur un continuum au lieu d’être précisée dans des classements fixes. Grâce au système à multiples composantes utilisé dans cette étude, il a été conclu que les deux adaptations filmiques choisies sont toutes les deux ‘approchantes’ et ‘libres’ aux points variés. La traduction intersémiotique utilisée dans les études comparatives des adaptations filmiques constitue donc un outil méthodologue indispensable qui permet une analyse détaillée et nuancée, et qui renforce les arguments en faveur de l’emploi d’un continuum de proximité qui contourne le problème d’étiquettes rigides et binaires. , Thesis (MA) -- Faculty of Humanities, French Studies, 2021
- Full Text:
- Date Issued: 2021-10-29
What are the pertinent intersections in the lives of black women at Rhodes University?
- Authors: Gushman, Lutho Phinda
- Date: 2021-10-29
- Subjects: Women, Black South Africa Makhanda , Student movements South Africa Makhanda , Intersectionality (Sociology) , Pluralism , Matrix organization South Africa Makhanda , Women, Black Education (Higher) South Africa Makhanda , Social action South Africa Makhanda , Rhodes University
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190990 , vital:45047
- Description: After the 2016 #FeesMustFall protest(s), higher education institutions were dramatically altered with respect to their institutional cultures; the narratives of those who were historically side-lined and marginalised took centre stage. At Rhodes University social activism was constitutive of three components; a ‘revolt’ against the fee increment; a contestation of the rape culture; and a rejection of the colonial curriculum. These concerns, in their varied articulations, made up different social and academic realities that define(d) Rhodes University and affected how individuals experienced institutional culture. According to Ndlovu (2017) while these expressed acts (in the form of protests and institutional shutdowns) of resistance against the system of higher education subsided after the fees must fall campaign, these served to centre the narratives of the marginalised. Keeping with this thinking, the argument presented in this thesis explores the experiences of black women in higher education after the call towards coordinated resistance. Using qualitative data in the form of narrative interviews, the thesis documents how the participants continued their academic and social life post-resistance. This rupture of resistance created a complex matrix of individual subjectivity where participants engaged with traditional social academic norms in new spaces of resistance; a phenomenon that enlivened the intersectionality that came to define the higher education landscape of the country. This thesis explores the stories of the participant’s as they engage(d) with what is becoming a new institution—that is the University in South Africa, with a case-in-point being Rhodes University—and to understand the power relations and intersections that define their lived experiences. This study found that the reality of existing within the confines of power—with its fluidity—meant that black women operate both within spaces of privilege and oppression simultaneously. As such, and following Vivian May’s (2015) argument, this study concludes that black women are situated and simultaneously constrained by power. Thus spaces of resistance are constantly in flux and determined by their relations within power. , Thesis (MA) -- Faculty of Humanities, Politics and International Studies, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Gushman, Lutho Phinda
- Date: 2021-10-29
- Subjects: Women, Black South Africa Makhanda , Student movements South Africa Makhanda , Intersectionality (Sociology) , Pluralism , Matrix organization South Africa Makhanda , Women, Black Education (Higher) South Africa Makhanda , Social action South Africa Makhanda , Rhodes University
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190990 , vital:45047
- Description: After the 2016 #FeesMustFall protest(s), higher education institutions were dramatically altered with respect to their institutional cultures; the narratives of those who were historically side-lined and marginalised took centre stage. At Rhodes University social activism was constitutive of three components; a ‘revolt’ against the fee increment; a contestation of the rape culture; and a rejection of the colonial curriculum. These concerns, in their varied articulations, made up different social and academic realities that define(d) Rhodes University and affected how individuals experienced institutional culture. According to Ndlovu (2017) while these expressed acts (in the form of protests and institutional shutdowns) of resistance against the system of higher education subsided after the fees must fall campaign, these served to centre the narratives of the marginalised. Keeping with this thinking, the argument presented in this thesis explores the experiences of black women in higher education after the call towards coordinated resistance. Using qualitative data in the form of narrative interviews, the thesis documents how the participants continued their academic and social life post-resistance. This rupture of resistance created a complex matrix of individual subjectivity where participants engaged with traditional social academic norms in new spaces of resistance; a phenomenon that enlivened the intersectionality that came to define the higher education landscape of the country. This thesis explores the stories of the participant’s as they engage(d) with what is becoming a new institution—that is the University in South Africa, with a case-in-point being Rhodes University—and to understand the power relations and intersections that define their lived experiences. This study found that the reality of existing within the confines of power—with its fluidity—meant that black women operate both within spaces of privilege and oppression simultaneously. As such, and following Vivian May’s (2015) argument, this study concludes that black women are situated and simultaneously constrained by power. Thus spaces of resistance are constantly in flux and determined by their relations within power. , Thesis (MA) -- Faculty of Humanities, Politics and International Studies, 2021
- Full Text:
- Date Issued: 2021-10-29
“This may not be your grandmother’s page, but we will definitely talk about her”: Lusaka women and the Zambian Feminists Facebook page
- Authors: Kasanga, Chishimba
- Date: 2021-10-29
- Subjects: Feminists Zambia , Social media and society Zambia , Facebook (Firm) , Feminism Africa , Women Zambia Social conditions , Sex role Zambia , Patriarchy Zambia , Digital activism , Zambian Feminists
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190122 , vital:44965
- Description: The internet has facilitated the creation of a global community of feminists who use it both for discussion and activism. Recently, high-profile campaigns, such as #MeToo and #AmINext, have garnered massive support online, attracting tens of thousands of women in diverse social and geographical spaces who have used the internet as forums for discussion and a route for activism. However, there are still parts of the world where feminism is a contentious topic, and one such place is Zambia, where the Facebook page Zambian Feminists, seeks to challenge patriarchy and gender non-conformity in a highly heteronormative society. This study investigates how prolific women fans of the Zambian Feminists page contest, negotiate and appropriate meanings from the posts and associated comments into their lives as “everyday feminists”. As a reception study, it inquires into how Lusaka women fans of the page negotiate their roles as strong feminists online and their offline social roles as women, mothers, daughters and wives living in a patriarchal and conservative society. The study draws primarily on qualitative research methods, specifically qualitative focus group discussions and individual in-depth interviews, to investigate this audience’s reception of the page’s content. The study establishes that Zambian Feminists is consumed in a complex environment where contesting notions of Christianity, traditionalism, and modernity are at play. The study also shows how a Christian nationalism discourse acts as a stumbling block to women fans identifying as feminists and women fans who identify as members of the LGBTIQ community, as they must negotiate and construct their identity against this prevailing discourse. The study concludes that inasmuch as the Zambian Feminist page provides a platform for women to ‘call out’ and challenge patriarchy, sexism and misogyny, the offline space is more difficult to overcome; Zambian women continue to conform to patriarchal norms as they construct and negotiate their feminism in line with the broader societal gender order. , Thesis (MA) -- Faculty of Humanities, Journalism and Media Studies, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Kasanga, Chishimba
- Date: 2021-10-29
- Subjects: Feminists Zambia , Social media and society Zambia , Facebook (Firm) , Feminism Africa , Women Zambia Social conditions , Sex role Zambia , Patriarchy Zambia , Digital activism , Zambian Feminists
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190122 , vital:44965
- Description: The internet has facilitated the creation of a global community of feminists who use it both for discussion and activism. Recently, high-profile campaigns, such as #MeToo and #AmINext, have garnered massive support online, attracting tens of thousands of women in diverse social and geographical spaces who have used the internet as forums for discussion and a route for activism. However, there are still parts of the world where feminism is a contentious topic, and one such place is Zambia, where the Facebook page Zambian Feminists, seeks to challenge patriarchy and gender non-conformity in a highly heteronormative society. This study investigates how prolific women fans of the Zambian Feminists page contest, negotiate and appropriate meanings from the posts and associated comments into their lives as “everyday feminists”. As a reception study, it inquires into how Lusaka women fans of the page negotiate their roles as strong feminists online and their offline social roles as women, mothers, daughters and wives living in a patriarchal and conservative society. The study draws primarily on qualitative research methods, specifically qualitative focus group discussions and individual in-depth interviews, to investigate this audience’s reception of the page’s content. The study establishes that Zambian Feminists is consumed in a complex environment where contesting notions of Christianity, traditionalism, and modernity are at play. The study also shows how a Christian nationalism discourse acts as a stumbling block to women fans identifying as feminists and women fans who identify as members of the LGBTIQ community, as they must negotiate and construct their identity against this prevailing discourse. The study concludes that inasmuch as the Zambian Feminist page provides a platform for women to ‘call out’ and challenge patriarchy, sexism and misogyny, the offline space is more difficult to overcome; Zambian women continue to conform to patriarchal norms as they construct and negotiate their feminism in line with the broader societal gender order. , Thesis (MA) -- Faculty of Humanities, Journalism and Media Studies, 2021
- Full Text:
- Date Issued: 2021-10-29
An evolutionary study of legless skinks’ (Acontias Cuvier, 1817) head and vertebrae morphology
- Authors: Evlambiou, Anthony Andreas
- Date: 2021-10
- Subjects: Skinks South Africa , Acontias South Africa , Typhlosaurus South Africa , Acontias Morphology , Acontias Phylogeny , Acontias Evolution , Vertebrae , Skull Growth , Evolutionary developmental biology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190690 , vital:45018
- Description: Environmental factors and/or processes can produce differences in general shape between individuals or particular parts of individuals. Examples of these biological processes may include ontogenetic development, adaptation to local geographic factors, or long-term evolutionary diversification. An organism is not likely to be able to optimise a single structure for multiple purposes and so trade-offs are likely to occur. An example of such a structure is the cranium, as it can be used for multiple activities such as defensive and sexual behaviour, locomotion, prey capture, and ingestion. Morphological characteristics have historically been used in the description of species. Genetic analyses have gained popularity as species delineation techniques and have been particularly useful in identifying cryptic species, especially among morphological conserved species like legless skinks of the subfamily Acontinae (e.g. Acontias Cuvier, 1817 and Typhlosaurus Weigmann, 1834). However, completely doing away with morphological techniques during species descriptions is not the best option. Therefore, novel methods to identify species, especially those with similar body plans, are needed. In this dissertation, we explore the links between head shape and vertebral number to environmental pressures to determine whether the evolutionary process is driven by environmental pressures (soil or biome) or is retained through ancestry. A novel species/clade delineation linked to vertebral number is also investigated. Head shape was expected to have a close link to the environment and the number of vertebrae was expected to have a closer link to ancestry. The first chapter investigates the drivers behind Acontias head shape evolution using geometric morphometric techniques. We found that environmental pressures did affect the evolution of head shape especially in the “soil” and “biome” categories but further investigation is advised. The second chapter explores the viability of using vertebral counts as a novel method for species and/or clade delineation in Acontias and to determine whether vertebral number can be linked to the environment. Delineating species based on vertebral count is likely not an option, however, delineating clades proved to show promising results. A link between vertebral count and environment was found in Acontias with larger bodied species occurring in different environments to smaller body species. In conclusion, the genus Acontias is difficult to delineate morphologically. Genetic sequence analyses can indicate differences and delineate the species. Even though there were differences in morphology based on environmental factors, it is not sufficient to delineate this subfamily alone. Further research is advised and this dissertation provides a good basis to work with. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Evlambiou, Anthony Andreas
- Date: 2021-10
- Subjects: Skinks South Africa , Acontias South Africa , Typhlosaurus South Africa , Acontias Morphology , Acontias Phylogeny , Acontias Evolution , Vertebrae , Skull Growth , Evolutionary developmental biology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190690 , vital:45018
- Description: Environmental factors and/or processes can produce differences in general shape between individuals or particular parts of individuals. Examples of these biological processes may include ontogenetic development, adaptation to local geographic factors, or long-term evolutionary diversification. An organism is not likely to be able to optimise a single structure for multiple purposes and so trade-offs are likely to occur. An example of such a structure is the cranium, as it can be used for multiple activities such as defensive and sexual behaviour, locomotion, prey capture, and ingestion. Morphological characteristics have historically been used in the description of species. Genetic analyses have gained popularity as species delineation techniques and have been particularly useful in identifying cryptic species, especially among morphological conserved species like legless skinks of the subfamily Acontinae (e.g. Acontias Cuvier, 1817 and Typhlosaurus Weigmann, 1834). However, completely doing away with morphological techniques during species descriptions is not the best option. Therefore, novel methods to identify species, especially those with similar body plans, are needed. In this dissertation, we explore the links between head shape and vertebral number to environmental pressures to determine whether the evolutionary process is driven by environmental pressures (soil or biome) or is retained through ancestry. A novel species/clade delineation linked to vertebral number is also investigated. Head shape was expected to have a close link to the environment and the number of vertebrae was expected to have a closer link to ancestry. The first chapter investigates the drivers behind Acontias head shape evolution using geometric morphometric techniques. We found that environmental pressures did affect the evolution of head shape especially in the “soil” and “biome” categories but further investigation is advised. The second chapter explores the viability of using vertebral counts as a novel method for species and/or clade delineation in Acontias and to determine whether vertebral number can be linked to the environment. Delineating species based on vertebral count is likely not an option, however, delineating clades proved to show promising results. A link between vertebral count and environment was found in Acontias with larger bodied species occurring in different environments to smaller body species. In conclusion, the genus Acontias is difficult to delineate morphologically. Genetic sequence analyses can indicate differences and delineate the species. Even though there were differences in morphology based on environmental factors, it is not sufficient to delineate this subfamily alone. Further research is advised and this dissertation provides a good basis to work with. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10
Building the field component of a smart irrigation system: A detailed experience of a computer science graduate
- Authors: Pipile, Yamnkelani Yonela
- Date: 2021-10
- Subjects: Irrigation efficiency Computer-aided design South Africa , Irrigation projects Computer-aided design South Africa , Internet of things , Machine-to-machine communications , Smart water grids South Africa , Raspberry Pi (Computer) , Arduino (Programmable controller) , ZigBee , MQTT (MQ Telemetry Transport) , MQTT-SN , XBee
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191814 , vital:45167
- Description: South Africa is a semi-arid area with an average annual rainfall of approximately 450mm, 60 per cent of which goes towards irrigation. Current irrigation systems generally apply water in a uniform manner across a field, which is both inefficient and can kill the plants. The Internet of Things (IoT), an emerging technology involving the utilization of sensors and actuators to build complex feedback systems, present an opportunity to build a smart irrigation solution. This research project illustrates the development of the field components of a water monitoring system using off the shelf and inexpensive components, exploring at the same time how easy or difficult it would be for a general Computer Science graduate to use hardware components and associated tools within the IoT area. The problem was initially broken down through a classical top-down process, in order to identify the components such as micro-computers, micro- controllers, sensors and network connections, that would be needed to build the solution. I then selected the Raspberry Pi 3, the Arduino Arduino Uno, the MH-Sensor-Series hygrometer, the MQTT messaging protocol, and the ZigBee communication protocol as implemented in the XBee S2C. Once the components were identified, the work followed a bottom-up approach: I studied the components in isolation and relative to each other, through a structured series of experiments, with each experiment addressing a specific component and examining how easy was to use the component. While each experiment allowed the author to acquire and deepen her understanding of each component, and progressively built a more sophisticated prototype, towards the complete solution. I found the vast majority of the identified components and tools to be easy to use, well documented, and most importantly, mature for consumption by our target user, until I encountered the MQTT-SN (MQTT-Sensor Network) implementation, not as mature as the rest. This resulted in us designing and implementing a light-weight, general ZigBee/MQTT gateway, named “yoGa” (Yonella's Gateway) from the author. At the end of the research, I was able to build the field components of a smart irrigation system using the selected tools, including the yoGa gateway, proving practically that a Computer Science graduate from a South African University can become productive in the emerging IoT area. , Thesis (MSc) -- Faculty of Science, Computer Science, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Pipile, Yamnkelani Yonela
- Date: 2021-10
- Subjects: Irrigation efficiency Computer-aided design South Africa , Irrigation projects Computer-aided design South Africa , Internet of things , Machine-to-machine communications , Smart water grids South Africa , Raspberry Pi (Computer) , Arduino (Programmable controller) , ZigBee , MQTT (MQ Telemetry Transport) , MQTT-SN , XBee
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191814 , vital:45167
- Description: South Africa is a semi-arid area with an average annual rainfall of approximately 450mm, 60 per cent of which goes towards irrigation. Current irrigation systems generally apply water in a uniform manner across a field, which is both inefficient and can kill the plants. The Internet of Things (IoT), an emerging technology involving the utilization of sensors and actuators to build complex feedback systems, present an opportunity to build a smart irrigation solution. This research project illustrates the development of the field components of a water monitoring system using off the shelf and inexpensive components, exploring at the same time how easy or difficult it would be for a general Computer Science graduate to use hardware components and associated tools within the IoT area. The problem was initially broken down through a classical top-down process, in order to identify the components such as micro-computers, micro- controllers, sensors and network connections, that would be needed to build the solution. I then selected the Raspberry Pi 3, the Arduino Arduino Uno, the MH-Sensor-Series hygrometer, the MQTT messaging protocol, and the ZigBee communication protocol as implemented in the XBee S2C. Once the components were identified, the work followed a bottom-up approach: I studied the components in isolation and relative to each other, through a structured series of experiments, with each experiment addressing a specific component and examining how easy was to use the component. While each experiment allowed the author to acquire and deepen her understanding of each component, and progressively built a more sophisticated prototype, towards the complete solution. I found the vast majority of the identified components and tools to be easy to use, well documented, and most importantly, mature for consumption by our target user, until I encountered the MQTT-SN (MQTT-Sensor Network) implementation, not as mature as the rest. This resulted in us designing and implementing a light-weight, general ZigBee/MQTT gateway, named “yoGa” (Yonella's Gateway) from the author. At the end of the research, I was able to build the field components of a smart irrigation system using the selected tools, including the yoGa gateway, proving practically that a Computer Science graduate from a South African University can become productive in the emerging IoT area. , Thesis (MSc) -- Faculty of Science, Computer Science, 2021
- Full Text:
- Date Issued: 2021-10
Ecological infrastructure importance for drought mitigation in rural South African catchments: the Cacadu Catchment case example
- Authors: Xoxo, Beauten Sinetemba
- Date: 2021-10
- Subjects: Sustainable Development Goals , Water security South Africa , Remote sensing , Watershed restoration South Africa , Restoration ecology South Africa , Ecosystem services South Africa , SDG 15.3.1
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191203 , vital:45070
- Description: Water scarcity is recognised as one of the significant challenges facing many countries, including South Africa. The threat of water scarcity is exacerbated by the coupled impacts of climate and anthropogenic drivers. Ongoing droughts and continued land cover change and degradation influence the ability of catchments to partition rainwater runoff, thereby affecting streamflow returns. However, quantifying land degradation accurately remains a challenge. This thesis used the theoretical lens of investing in ecological infrastructure to improve the drought mitigation function in rural catchments. This theoretical framework allows for a social-ecological systems approach to understand and facilitate science-based strategies for promoting ecosystem recovery. Specifically, this study aimed to explore the role and benefit of ecological infrastructure for improving drought mitigation, and consequently, water security for rural communities. Thus, this study sought to assess the consequences of human actions to catchment health status using the 15th Sustainable Development Goal indicator for the proportion of degraded land over the total land area as a surrogate. Secondly, hydrological modelling was used to describe how different land covers influence catchment hydrology, which related to how ecological infrastructure enables drought risk-reduction for mitigation regulation. Finally, this study developed a spatial prioritisation plan for restoration to improve drought mitigation for four focal ecological infrastructure (EI) categories (i.e. wetlands, riparian margins, abandoned agricultural fields and grasslands). The focal EI categories were selected for their importance in delivering water-related ecosystem services when sustainably managed. Chapter 1 sets the scene (i.e. provides the study background) and Chapter 2 provides a review of the literature. In Chapter 3, the recently released global GIS toolbox (TRENDS.EARTH) was used for tracking land change and for assessing the SDG 15.3.1 degradation indicator of i.e. Cacadu catchment over 15 years at a 300 m resolution. The results showed a declining trend in biomass productivity within the Cacadu catchment led to moderate degradation, with 16.79% of the total landscape degraded, which was determined by the pugin using the one-out, all-out rule. The incidence of degradation was detected in middle reaches of the catchment (i.e. S10F-J), while some improvement was detected in upper reaches (S10A-C) and lower reaches (S10J). In Chapter 4, a GIS-based Analytic Hierarchical Process (AHP) based on community stakeholder priorities, open-access spatial datasets and expert opinions, was used to identify EI focal areas that are best suitable for restoration to increase the drought mitigation capacity of the Cacadu catchment. The collected datasets provided three broad criteria (ecosystem health, water provision and social benefit) for establishing the AHP model using 12 spatial attributes. Prioritisation results show that up to 89% of the Cacadu catchment is suitable for restoration to improve drought mitigation. Catchments S10B-D, and S10F, S10G and S10J were highly prioritised while S10A, S10E and S10H received low priority, due to improving environmental conditions and low hydrological potential. Areas that were prioritised with consideration for local livelihoods overlap the areas for drought mitigation and form a network of villages from the middle to lower catchment reaches. Prioritised restoration areas with a consideration of societal benefit made up 0.56% of wetlands, 4.27% of riparian margins, 92.06% of abandoned croplands, and 51.86% of grasslands. Chapter 5 reports on use of the Pitman groundwater model to help understand the influence of land modification on catchment hydrology, and highlight the role of restoration interventions. The Cacadu catchment is ungauged, therefore the neighbouring Indwe catchment was used for parameter transfer through a spatial regionalisation technique. Results suggest that degradation increases surface runoff and aggravates recharge reduction, thereby reducing streamflow during low flow periods. In areas where there is natural land cover recovery, the Pitman Model simulated similar dry season streamflow to the natural land cover. Combining the outcomes from the three assessments allowed the study to highlight the role and benefits of ecological infrastructure in terms of drought mitigation. Study findings were interpreted to make recommendations for the role and benefit of ecological infrastructure for drought mitigation at a landscape scale and tertiary catchment level, within the context of available management options. The results support the notion that multiple science data sources can promote investments in ecological infrastructure. However, better spatial and temporal resolution datasets at a national level are still needed to improve the accuracy of studies such as the one outlined in this thesis. The study recommends adopting better ecosystem protection approaches and collaborative governance at multiple levels to reduce the vulnerability of rural communities to drought impacts. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Xoxo, Beauten Sinetemba
- Date: 2021-10
- Subjects: Sustainable Development Goals , Water security South Africa , Remote sensing , Watershed restoration South Africa , Restoration ecology South Africa , Ecosystem services South Africa , SDG 15.3.1
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191203 , vital:45070
- Description: Water scarcity is recognised as one of the significant challenges facing many countries, including South Africa. The threat of water scarcity is exacerbated by the coupled impacts of climate and anthropogenic drivers. Ongoing droughts and continued land cover change and degradation influence the ability of catchments to partition rainwater runoff, thereby affecting streamflow returns. However, quantifying land degradation accurately remains a challenge. This thesis used the theoretical lens of investing in ecological infrastructure to improve the drought mitigation function in rural catchments. This theoretical framework allows for a social-ecological systems approach to understand and facilitate science-based strategies for promoting ecosystem recovery. Specifically, this study aimed to explore the role and benefit of ecological infrastructure for improving drought mitigation, and consequently, water security for rural communities. Thus, this study sought to assess the consequences of human actions to catchment health status using the 15th Sustainable Development Goal indicator for the proportion of degraded land over the total land area as a surrogate. Secondly, hydrological modelling was used to describe how different land covers influence catchment hydrology, which related to how ecological infrastructure enables drought risk-reduction for mitigation regulation. Finally, this study developed a spatial prioritisation plan for restoration to improve drought mitigation for four focal ecological infrastructure (EI) categories (i.e. wetlands, riparian margins, abandoned agricultural fields and grasslands). The focal EI categories were selected for their importance in delivering water-related ecosystem services when sustainably managed. Chapter 1 sets the scene (i.e. provides the study background) and Chapter 2 provides a review of the literature. In Chapter 3, the recently released global GIS toolbox (TRENDS.EARTH) was used for tracking land change and for assessing the SDG 15.3.1 degradation indicator of i.e. Cacadu catchment over 15 years at a 300 m resolution. The results showed a declining trend in biomass productivity within the Cacadu catchment led to moderate degradation, with 16.79% of the total landscape degraded, which was determined by the pugin using the one-out, all-out rule. The incidence of degradation was detected in middle reaches of the catchment (i.e. S10F-J), while some improvement was detected in upper reaches (S10A-C) and lower reaches (S10J). In Chapter 4, a GIS-based Analytic Hierarchical Process (AHP) based on community stakeholder priorities, open-access spatial datasets and expert opinions, was used to identify EI focal areas that are best suitable for restoration to increase the drought mitigation capacity of the Cacadu catchment. The collected datasets provided three broad criteria (ecosystem health, water provision and social benefit) for establishing the AHP model using 12 spatial attributes. Prioritisation results show that up to 89% of the Cacadu catchment is suitable for restoration to improve drought mitigation. Catchments S10B-D, and S10F, S10G and S10J were highly prioritised while S10A, S10E and S10H received low priority, due to improving environmental conditions and low hydrological potential. Areas that were prioritised with consideration for local livelihoods overlap the areas for drought mitigation and form a network of villages from the middle to lower catchment reaches. Prioritised restoration areas with a consideration of societal benefit made up 0.56% of wetlands, 4.27% of riparian margins, 92.06% of abandoned croplands, and 51.86% of grasslands. Chapter 5 reports on use of the Pitman groundwater model to help understand the influence of land modification on catchment hydrology, and highlight the role of restoration interventions. The Cacadu catchment is ungauged, therefore the neighbouring Indwe catchment was used for parameter transfer through a spatial regionalisation technique. Results suggest that degradation increases surface runoff and aggravates recharge reduction, thereby reducing streamflow during low flow periods. In areas where there is natural land cover recovery, the Pitman Model simulated similar dry season streamflow to the natural land cover. Combining the outcomes from the three assessments allowed the study to highlight the role and benefits of ecological infrastructure in terms of drought mitigation. Study findings were interpreted to make recommendations for the role and benefit of ecological infrastructure for drought mitigation at a landscape scale and tertiary catchment level, within the context of available management options. The results support the notion that multiple science data sources can promote investments in ecological infrastructure. However, better spatial and temporal resolution datasets at a national level are still needed to improve the accuracy of studies such as the one outlined in this thesis. The study recommends adopting better ecosystem protection approaches and collaborative governance at multiple levels to reduce the vulnerability of rural communities to drought impacts. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-10
Evaluation of Megabruchidius tonkineus (Coleoptera: Chrysomelidae: Bruchinae), a candidate biological control agent for Gleditsia triacanthos L. (Fabaceae) in South Africa
- Salgado Astudillo, Sara Elizabeth
- Authors: Salgado Astudillo, Sara Elizabeth
- Date: 2021-10
- Subjects: Honey locust South Africa , Honey locust Biological control South Africa , Invasive plants Biological control South Africa , Biogeography South Africa , Biogeography Climatic factors South Africa , Megabruchidius tonkineus South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/188386 , vital:44749
- Description: Gleditsia triacanthos L. (Fabaceae) (honey locust) is a fast-growing, deciduous tree indigenous to the United States of America. Introduced around the world as an ornamental tree, it has become invasive in a number of countries. Where it is invasive, G. triacanthos competes and replaces indigenous species; it creates dense stands along watercourses, posing a significant environmental threat. In South Africa, G. triacanthos is regarded as one of the country’s fastest spreading weeds. Gleditsia triacanthos produces numerous seeds contained in large hanging pods. Once dislodged from the pods, the seeds are dispersed by birds and mammals, including livestock, which eat the pods. It has been suggested that the seeds should be the target for biological control programme. Some invasive alien plant species are characterised by their ability to spread and establish in new ecosystems because they tolerate a wide range of environmental conditions. In order to predict areas of likely invasion, species distribution models (SDMs) are used to identify areas climatically suitable for their invasion, so enabling better targeted control of the plant species. Gleditsia triacanthos adapts to a wide range of climates and soil types, and tolerates salinity, drought and frost. Currently primarily restricted to the Grassland Biome of South Africa, G. triacanthos has doubled its distribution area in the past 15 years, and it is not known how far the species will spread. In this study we used two different modelling programmes, CLIMEX and MaxEnt, to predict areas where G. triacanthos could find favourable growing conditions; both SDMs showed that most of the country is suitable for G. triacanthos and that it will probably continue to spread, if left unmanaged, into new bioregions, such as the Karoo. In South Africa, the Asian seed-feeding bruchid, Megabruchidius tonkineus (Pic, 1914) (Coleoptera: Chrysomelidae: Bruchinae) has been recorded in the plant’s seed pods and has been considered as a biological control agent. The insect was not released as part of a formal biological control programme and neither host-specificity nor impact studies were conducted on the species prior to its discovery. In 2017 a decision was made to re-consider its status as a Abstract biological control agent until further details of its biology, host specificity, and impact on the seeds of G. triacanthos in South Africa were available. This study shows that Megabruchidius tonkineus has established across the entire G. triacanthos population in South Africa damaging approximately 9% of seeds. Laboratory studies show that, Megabruchidius tonkineus completes its larval development in the seeds of G. triacanthos in about 66.80 ± 0.6880 SE days before eclosing. In addition, the adult females oviposit on the following Fabaceae species: Arachis hypogaea, Albizia, julibrissin, Cicer arietinum, Pisum sativum, Dipogon lignosus, Peltophorum africanum, Podalyria buxifolia Senegalia burkei, Umtiza listerina and Vachellia sieberiana. However, larval development was limited to G. triacanthos. It is concluded that the seed-feeding beetle is not a threat to native Fabaceae species in South Africa, however, it does not damage enough G. triacanthos seeds to be considered a valuable biological control agent at this stage, and additional seed-feeding biological control agents should be considered to reduce the number of G. triacanthos seeds entering the environment. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Salgado Astudillo, Sara Elizabeth
- Date: 2021-10
- Subjects: Honey locust South Africa , Honey locust Biological control South Africa , Invasive plants Biological control South Africa , Biogeography South Africa , Biogeography Climatic factors South Africa , Megabruchidius tonkineus South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/188386 , vital:44749
- Description: Gleditsia triacanthos L. (Fabaceae) (honey locust) is a fast-growing, deciduous tree indigenous to the United States of America. Introduced around the world as an ornamental tree, it has become invasive in a number of countries. Where it is invasive, G. triacanthos competes and replaces indigenous species; it creates dense stands along watercourses, posing a significant environmental threat. In South Africa, G. triacanthos is regarded as one of the country’s fastest spreading weeds. Gleditsia triacanthos produces numerous seeds contained in large hanging pods. Once dislodged from the pods, the seeds are dispersed by birds and mammals, including livestock, which eat the pods. It has been suggested that the seeds should be the target for biological control programme. Some invasive alien plant species are characterised by their ability to spread and establish in new ecosystems because they tolerate a wide range of environmental conditions. In order to predict areas of likely invasion, species distribution models (SDMs) are used to identify areas climatically suitable for their invasion, so enabling better targeted control of the plant species. Gleditsia triacanthos adapts to a wide range of climates and soil types, and tolerates salinity, drought and frost. Currently primarily restricted to the Grassland Biome of South Africa, G. triacanthos has doubled its distribution area in the past 15 years, and it is not known how far the species will spread. In this study we used two different modelling programmes, CLIMEX and MaxEnt, to predict areas where G. triacanthos could find favourable growing conditions; both SDMs showed that most of the country is suitable for G. triacanthos and that it will probably continue to spread, if left unmanaged, into new bioregions, such as the Karoo. In South Africa, the Asian seed-feeding bruchid, Megabruchidius tonkineus (Pic, 1914) (Coleoptera: Chrysomelidae: Bruchinae) has been recorded in the plant’s seed pods and has been considered as a biological control agent. The insect was not released as part of a formal biological control programme and neither host-specificity nor impact studies were conducted on the species prior to its discovery. In 2017 a decision was made to re-consider its status as a Abstract biological control agent until further details of its biology, host specificity, and impact on the seeds of G. triacanthos in South Africa were available. This study shows that Megabruchidius tonkineus has established across the entire G. triacanthos population in South Africa damaging approximately 9% of seeds. Laboratory studies show that, Megabruchidius tonkineus completes its larval development in the seeds of G. triacanthos in about 66.80 ± 0.6880 SE days before eclosing. In addition, the adult females oviposit on the following Fabaceae species: Arachis hypogaea, Albizia, julibrissin, Cicer arietinum, Pisum sativum, Dipogon lignosus, Peltophorum africanum, Podalyria buxifolia Senegalia burkei, Umtiza listerina and Vachellia sieberiana. However, larval development was limited to G. triacanthos. It is concluded that the seed-feeding beetle is not a threat to native Fabaceae species in South Africa, however, it does not damage enough G. triacanthos seeds to be considered a valuable biological control agent at this stage, and additional seed-feeding biological control agents should be considered to reduce the number of G. triacanthos seeds entering the environment. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10
Green Synthesis of HIV-1 Protease Inhibitors
- Authors: Hartley, Shaun Neil
- Date: 2021-10
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190145 , vital:44967
- Description: Thesis embargoed until October 2022 , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Hartley, Shaun Neil
- Date: 2021-10
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190145 , vital:44967
- Description: Thesis embargoed until October 2022 , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10
Modification of Gelatin-Methacrylate, Hyaluronic-Methacrylate and Poly(ethylene) glycol Diacrylate hydrogel bioinks towards the additive manufacturing of articular cartilage
- Authors: Barwick, Matthew William
- Date: 2021-10
- Subjects: Cartilage Diseases , Cartilage Regeneration , Articular cartilage Diseases , Chondrogenesis , Stem cells , Scanning electron microscopy , Fourier transform infrared spectroscopy , Three-dimensional printing , Gelatin-Methacrylate , Hyaluronic-Methacrylate , Poly(ethylene) glycolDiacrylate , Hydrogel bioinks , Real-Time Quantitative Cell Analysis (RTCA) , Bioprinting
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191181 , vital:45068
- Description: Cartilage degradation is most commonly associated with Rheumatoid arthritis and Osteoarthritis, affecting millions of people worldwide. Joint transplants commonly use titanium alloys, which have a shelf life of between 10-15 years. Although the titanium transplant restores partial mobility, side effects such as inflammation, swelling, faulty implants, and metal poisoning in some cases resulting from the transplant. The use of additive manufacturing of articular cartilage sheds new, innovative prospects for joint replacements. This study sets out to formulate and characterize five different hydrogel types towards the additive manufacturing of articular cartilage. Chondrogenic and Adipogenic differentiation was carried out on two separate adipose-mesenchymal stem cell lines A270620-01A, and A311019-02T and validation and efficiency of the differentiation and chondrogenic gene expression was carried out using Alcian Blue stain, Oil Red O stain and Quantitative Reverse Transcription PCR (RT-qPCR). Hydrogel formulation and characterisation of 10 % Gelatin-methacryloyl (GelMA), 10 % Poly (ethylene) glycol diacrylate (PEGDA), 5 % GelMA/5 % PEGDA, 10 % GelMA/0.5 % Hyaluronic Acid Methacrylate (HAMA) and 10 % PEGDA/0.5 % HAMA was carried out through swelling and degradation ratios, surface area and porosity characterisation using Scanning Electron Microscopy (SEM). Hydrogel component and spectroscopic analysis were carried using Real-Time Quantitative Cell Analysis (RTCA) and Fourier-transform Infrared Spectroscopy (FTIR) analysis for each formulated hydrogel's chemical characterisation. Three-dimensional printing (3D) of 10 % PEGDA/0.5 % HAMA and 5 % GelMA/5 % PEGDA was performed using the Zortrax INKSPIRE Resin Ultra-Violet (UV) LCD Desktop 3D Printer. Hydrogel sterility and cell viability were carried out for each hydrogel type using fluorescence microscopy. Both A270620-01A and A311019-02T cell lines showed adipogenic and chondrogenic differentiation ability, with A311019-02T cell line showing greater chondrogenic differentiation of Alcian blue staining. The A270620-01A cell line resulted in a greater collagen gene expression based on the RT-qPCR results. The hydrogel 10 % GelMA showed the greatest swelling ratio of 1260 % in DPBS and 1192 % in DMEM. A significant difference between hydrogel swelling and swelling with Dulbecco's Phosphate Buffered Saline (DPBS) and Dulbecco’s Modified Eagle Medium (DMEM) was observed. The 10 % PEGDA hydrogel had the greatest degradation ratio of 59 % mass remaining, where the 10 % GelMA/0.5 % HAMA showed the least amount of degradation with a mass remaining at 91 %. The 10 % GelMA showed the greatest porosity will the largest pore size of 14 μm in diameter. Hydrogel component and spectroscopic analysis showed no cytotoxic effects for the visible light photoinitiator used to polymerize the hydrogel and no cytotoxic effects for the concentrations used in chondrogenic differentiation. The FTIR analysis showed partial gelatin and hyaluronic acid modification with methacrylic anhydride; however, the distinction between the hybrid hydrogels and single polymer hydrogels could not be made effectively. UV and ethanol washing showed to completely sterilise the hydrogel disks from any contaminants, making them suitable for tissue culture. The cell viability analysis showed the 10 % GelMA/HAMA having the highest cell viability of 77.3 % using 5000 cells/disk and 89.64 % viability using 50 000 cells/disk over a 7-day incubation period. Overall, the combination of two polymers, GelMA and HAMA, has good potential as a 3D hydrogel scaffold towards additive manufacturing of articular cartilage. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Barwick, Matthew William
- Date: 2021-10
- Subjects: Cartilage Diseases , Cartilage Regeneration , Articular cartilage Diseases , Chondrogenesis , Stem cells , Scanning electron microscopy , Fourier transform infrared spectroscopy , Three-dimensional printing , Gelatin-Methacrylate , Hyaluronic-Methacrylate , Poly(ethylene) glycolDiacrylate , Hydrogel bioinks , Real-Time Quantitative Cell Analysis (RTCA) , Bioprinting
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191181 , vital:45068
- Description: Cartilage degradation is most commonly associated with Rheumatoid arthritis and Osteoarthritis, affecting millions of people worldwide. Joint transplants commonly use titanium alloys, which have a shelf life of between 10-15 years. Although the titanium transplant restores partial mobility, side effects such as inflammation, swelling, faulty implants, and metal poisoning in some cases resulting from the transplant. The use of additive manufacturing of articular cartilage sheds new, innovative prospects for joint replacements. This study sets out to formulate and characterize five different hydrogel types towards the additive manufacturing of articular cartilage. Chondrogenic and Adipogenic differentiation was carried out on two separate adipose-mesenchymal stem cell lines A270620-01A, and A311019-02T and validation and efficiency of the differentiation and chondrogenic gene expression was carried out using Alcian Blue stain, Oil Red O stain and Quantitative Reverse Transcription PCR (RT-qPCR). Hydrogel formulation and characterisation of 10 % Gelatin-methacryloyl (GelMA), 10 % Poly (ethylene) glycol diacrylate (PEGDA), 5 % GelMA/5 % PEGDA, 10 % GelMA/0.5 % Hyaluronic Acid Methacrylate (HAMA) and 10 % PEGDA/0.5 % HAMA was carried out through swelling and degradation ratios, surface area and porosity characterisation using Scanning Electron Microscopy (SEM). Hydrogel component and spectroscopic analysis were carried using Real-Time Quantitative Cell Analysis (RTCA) and Fourier-transform Infrared Spectroscopy (FTIR) analysis for each formulated hydrogel's chemical characterisation. Three-dimensional printing (3D) of 10 % PEGDA/0.5 % HAMA and 5 % GelMA/5 % PEGDA was performed using the Zortrax INKSPIRE Resin Ultra-Violet (UV) LCD Desktop 3D Printer. Hydrogel sterility and cell viability were carried out for each hydrogel type using fluorescence microscopy. Both A270620-01A and A311019-02T cell lines showed adipogenic and chondrogenic differentiation ability, with A311019-02T cell line showing greater chondrogenic differentiation of Alcian blue staining. The A270620-01A cell line resulted in a greater collagen gene expression based on the RT-qPCR results. The hydrogel 10 % GelMA showed the greatest swelling ratio of 1260 % in DPBS and 1192 % in DMEM. A significant difference between hydrogel swelling and swelling with Dulbecco's Phosphate Buffered Saline (DPBS) and Dulbecco’s Modified Eagle Medium (DMEM) was observed. The 10 % PEGDA hydrogel had the greatest degradation ratio of 59 % mass remaining, where the 10 % GelMA/0.5 % HAMA showed the least amount of degradation with a mass remaining at 91 %. The 10 % GelMA showed the greatest porosity will the largest pore size of 14 μm in diameter. Hydrogel component and spectroscopic analysis showed no cytotoxic effects for the visible light photoinitiator used to polymerize the hydrogel and no cytotoxic effects for the concentrations used in chondrogenic differentiation. The FTIR analysis showed partial gelatin and hyaluronic acid modification with methacrylic anhydride; however, the distinction between the hybrid hydrogels and single polymer hydrogels could not be made effectively. UV and ethanol washing showed to completely sterilise the hydrogel disks from any contaminants, making them suitable for tissue culture. The cell viability analysis showed the 10 % GelMA/HAMA having the highest cell viability of 77.3 % using 5000 cells/disk and 89.64 % viability using 50 000 cells/disk over a 7-day incubation period. Overall, the combination of two polymers, GelMA and HAMA, has good potential as a 3D hydrogel scaffold towards additive manufacturing of articular cartilage. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2021
- Full Text:
- Date Issued: 2021-10
Nonlinear optical properties of metal free thio alkyl and tert-butyl phenoxy phthalocyanine
- Authors: Joseph, Otto
- Date: 2021-10
- Subjects: Nonlinear optics , Phthalocyanines , Time-dependent density functional theory , Magnetic circular dichroism , Reverse saturable absorption (RSA) , Real Time Dependent Density Functional Theory (RT-TDDFT)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190712 , vital:45021
- Description: This work reports on the nonlinear optical properties of tetra - and octa substituted phthalocyanines (Pcs) utilising pentane thiol and 4-tertbutyl phenol as substituents. Their nonlinear absorption coefficient (𝛽) and absorption cross sections were determined using the Z-scan technique with a 10 ns pulse laser at 532 nm. The molecular second order hyperpolarizability Im[γ] was observed and the following Im[γ] trend was obtained for 𝛼-H2Pc(SC5H11)4 isomers, 5.93 ×10−31 (Cs) 2.24×10−32(D2h) > 1.21×10−32(C4h) > 1.05×10−32 (C2v) esu, respectively, in chloroform. Symmetry was seen to have an effect on the observed reverse saturable absorption (RSA) response. Based on the five level model rate equation nonlinear fit of the RSA response curves and Real Time Time Dependant Density Functional Theory (RT-TDDFT) results, the singlet excited state population dynamics was found to play a significant role in producing the observed Im[γ] trend. , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Joseph, Otto
- Date: 2021-10
- Subjects: Nonlinear optics , Phthalocyanines , Time-dependent density functional theory , Magnetic circular dichroism , Reverse saturable absorption (RSA) , Real Time Dependent Density Functional Theory (RT-TDDFT)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190712 , vital:45021
- Description: This work reports on the nonlinear optical properties of tetra - and octa substituted phthalocyanines (Pcs) utilising pentane thiol and 4-tertbutyl phenol as substituents. Their nonlinear absorption coefficient (𝛽) and absorption cross sections were determined using the Z-scan technique with a 10 ns pulse laser at 532 nm. The molecular second order hyperpolarizability Im[γ] was observed and the following Im[γ] trend was obtained for 𝛼-H2Pc(SC5H11)4 isomers, 5.93 ×10−31 (Cs) 2.24×10−32(D2h) > 1.21×10−32(C4h) > 1.05×10−32 (C2v) esu, respectively, in chloroform. Symmetry was seen to have an effect on the observed reverse saturable absorption (RSA) response. Based on the five level model rate equation nonlinear fit of the RSA response curves and Real Time Time Dependant Density Functional Theory (RT-TDDFT) results, the singlet excited state population dynamics was found to play a significant role in producing the observed Im[γ] trend. , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10
Nurturing an identity of land custodianship of young people through a biodiversity learning programme: The Moletele Youth Learning Programme
- Authors: Mponwana, William Oupa
- Date: 2021-10
- Subjects: Sustainable biodiversity South Africa Mopani District Municipality , Association for Water and Rural Development (South Africa) , Land reform beneficiaries South Africa Mopani District Municipality , Agricultural development projects South Africa Mopani District Municipality , Land use Study and teaching South Africa Mopani District Municipality , Identity (Psychology) Social aspects South Africa Mopani District Municipality , Identity (Psychology) in youth South Africa Mopani District Municipality , Moletele Youth Learning Programme , Moletele Communal Property Association (CPA) , RESILIM-O
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/10962/188820 , vital:44789
- Description: This study was an exploration of value creation through scaffolding in a context specific learning programme with young people within the Moletele Communal Property Association (CPA) who own land through the land reform programme in South Africa. The study aimed to support the development the identity of land custodianship amongst young people by developing their skills and competencies in a situated learning context. The study also informed ongoing support work through the RESILIM-O resilience building project implemented by the Association for Water and Rural Development (AWARD) to help the Moletele Community Property Association to better understand the implications of biodiversity and land use for developing sustainable beneficiation projects and planning. A case study approach was adopted through a learning programme with young people as an in-depth exploration of the complexities of land and biodiversity. Data were collected during sessions in the learning programme where we used a spiral framework to facilitate learning focusing on four themes for primary data: knowledge competence, technical skills, self-organization and collective agency which are linked to building an identity of custodianship. Semi structured interviews were conducted at the end of the learning programme as a secondary data source. The study found that scaffolding remained an important process throughout the learning programme, and different types of scaffolding was needed to support the learning processes and themes. Furthermore, different types of value were created over time through the interactions and activities of the learning programme. The study also found that young people have a desire to participate in their communal property association. Lastly the study revealed that building custodianship as an identity is a continuous, long term process that needs commitment of time, resources and supportive learning processes, for an identity of custodianship to emerge. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Mponwana, William Oupa
- Date: 2021-10
- Subjects: Sustainable biodiversity South Africa Mopani District Municipality , Association for Water and Rural Development (South Africa) , Land reform beneficiaries South Africa Mopani District Municipality , Agricultural development projects South Africa Mopani District Municipality , Land use Study and teaching South Africa Mopani District Municipality , Identity (Psychology) Social aspects South Africa Mopani District Municipality , Identity (Psychology) in youth South Africa Mopani District Municipality , Moletele Youth Learning Programme , Moletele Communal Property Association (CPA) , RESILIM-O
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/10962/188820 , vital:44789
- Description: This study was an exploration of value creation through scaffolding in a context specific learning programme with young people within the Moletele Communal Property Association (CPA) who own land through the land reform programme in South Africa. The study aimed to support the development the identity of land custodianship amongst young people by developing their skills and competencies in a situated learning context. The study also informed ongoing support work through the RESILIM-O resilience building project implemented by the Association for Water and Rural Development (AWARD) to help the Moletele Community Property Association to better understand the implications of biodiversity and land use for developing sustainable beneficiation projects and planning. A case study approach was adopted through a learning programme with young people as an in-depth exploration of the complexities of land and biodiversity. Data were collected during sessions in the learning programme where we used a spiral framework to facilitate learning focusing on four themes for primary data: knowledge competence, technical skills, self-organization and collective agency which are linked to building an identity of custodianship. Semi structured interviews were conducted at the end of the learning programme as a secondary data source. The study found that scaffolding remained an important process throughout the learning programme, and different types of scaffolding was needed to support the learning processes and themes. Furthermore, different types of value were created over time through the interactions and activities of the learning programme. The study also found that young people have a desire to participate in their communal property association. Lastly the study revealed that building custodianship as an identity is a continuous, long term process that needs commitment of time, resources and supportive learning processes, for an identity of custodianship to emerge. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10
Potential Synergism between Entomopathogenic Fungi and Entomopathogenic Nematodes for the control of false codling moth (Thaumatotibia leucotreta)
- Authors: Prinsloo, Samantha Lee
- Date: 2021-10
- Subjects: Cryptophlebia leucotreta , Entomopathogenic fungi , Insect nematodes , Citrus Diseases and pests , Cryptophlebia leucotreta Biological control , Pests Integrated control , Biological pest control agents
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/10962/188832 , vital:44790
- Description: False codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) (FCM), is a major phytosanitary pest of citrus in South Africa. Sufficient control measures for the soil-dwelling life stages of FCM have yet to be identified and owing to restrictions on the use of insecticides, non-chemical control options have been investigated including the use of entomopathogenic fungi (EPF) and entomopathogenic nematodes (EPN). Laboratory and field trials on an indigenous EPF, Metarhizium anisopliae FCM Ar 23 B3, have shown that this isolate is capable of inducing mortality in FCM soil-dwelling life stages. Other agents that have been highlighted as potential controls for soil-dwelling FCM life stages are the EPN species Steinernema yirgalemense 157-C, S. jeffreyense J194 and H. noenieputensis 158-C. This study conducted laboratory bioassays to assess the virulence of these four control agents on fifth instar FCM, in 24-well plates. These results reaffirmed the virulence of the four microbial control agents at their recommended doses of 50 IJs (EPN) and 1×107 conidia/ml (EPF) against fifth instar FCM with 80 to 96% larval mortality recorded. The EPF isolate exhibited the lowest mortality whilst S. yirgalemense induced the greatest mortality. In addition, the lethal concentration (LC) values for each isolate were determined using dose response bioassays. These values were previously unknown for all EPN species and for the EPF isolate based on the methodology used in this study. The LC50 results in order from lowest to highest EPN IJ concentration requirements were 4.38 IJs (S. yirgalemense), 4.47 IJs (S. jeffreyense) and 7.11 IJs (H. noenieputensis). The EPF isolate exhibited an LC50 of 3.42×105 conidia/ml. Lastly, research has shown that the combination of two control agents may increase control of late instar lepidopteran and coleopteran larvae, through synergistic interactions. Thus, the interactions that occurred between the combination of these EPN species with the EPF isolate were determined. This study found that when all three EPN species were combined simultaneously and sequentially with the EPF isolate M. anisopliae FCM AR 23 B3, additive interactions took place with exception of the simultaneous application of S. yirgalemense and H. noenieputensis, with the EPF and S. jeffreyense applied 24 h post EPF application. For the former, a synergistic interaction was found, whilst for the latter two, an antagonistic interaction. Although no strongly synergistic interactions were observed, additive interactions have been shown to reach a synergistic level when certain parameters are changed. Moving forward, a uniform methodology for conducting EPF/EPN interaction experiments has been suggested. It has also been recommended that due to the additive interactions observed in this study, laboratory soil-bioassays and field trials should be carried out for all three EPN species in combination with the EPF isolate. This research will inevitably facilitate the constant knowledge into management strategies for the phytosanitary pest, FCM in South African citrus. , Thesis (MSc) -- Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Prinsloo, Samantha Lee
- Date: 2021-10
- Subjects: Cryptophlebia leucotreta , Entomopathogenic fungi , Insect nematodes , Citrus Diseases and pests , Cryptophlebia leucotreta Biological control , Pests Integrated control , Biological pest control agents
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/10962/188832 , vital:44790
- Description: False codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) (FCM), is a major phytosanitary pest of citrus in South Africa. Sufficient control measures for the soil-dwelling life stages of FCM have yet to be identified and owing to restrictions on the use of insecticides, non-chemical control options have been investigated including the use of entomopathogenic fungi (EPF) and entomopathogenic nematodes (EPN). Laboratory and field trials on an indigenous EPF, Metarhizium anisopliae FCM Ar 23 B3, have shown that this isolate is capable of inducing mortality in FCM soil-dwelling life stages. Other agents that have been highlighted as potential controls for soil-dwelling FCM life stages are the EPN species Steinernema yirgalemense 157-C, S. jeffreyense J194 and H. noenieputensis 158-C. This study conducted laboratory bioassays to assess the virulence of these four control agents on fifth instar FCM, in 24-well plates. These results reaffirmed the virulence of the four microbial control agents at their recommended doses of 50 IJs (EPN) and 1×107 conidia/ml (EPF) against fifth instar FCM with 80 to 96% larval mortality recorded. The EPF isolate exhibited the lowest mortality whilst S. yirgalemense induced the greatest mortality. In addition, the lethal concentration (LC) values for each isolate were determined using dose response bioassays. These values were previously unknown for all EPN species and for the EPF isolate based on the methodology used in this study. The LC50 results in order from lowest to highest EPN IJ concentration requirements were 4.38 IJs (S. yirgalemense), 4.47 IJs (S. jeffreyense) and 7.11 IJs (H. noenieputensis). The EPF isolate exhibited an LC50 of 3.42×105 conidia/ml. Lastly, research has shown that the combination of two control agents may increase control of late instar lepidopteran and coleopteran larvae, through synergistic interactions. Thus, the interactions that occurred between the combination of these EPN species with the EPF isolate were determined. This study found that when all three EPN species were combined simultaneously and sequentially with the EPF isolate M. anisopliae FCM AR 23 B3, additive interactions took place with exception of the simultaneous application of S. yirgalemense and H. noenieputensis, with the EPF and S. jeffreyense applied 24 h post EPF application. For the former, a synergistic interaction was found, whilst for the latter two, an antagonistic interaction. Although no strongly synergistic interactions were observed, additive interactions have been shown to reach a synergistic level when certain parameters are changed. Moving forward, a uniform methodology for conducting EPF/EPN interaction experiments has been suggested. It has also been recommended that due to the additive interactions observed in this study, laboratory soil-bioassays and field trials should be carried out for all three EPN species in combination with the EPF isolate. This research will inevitably facilitate the constant knowledge into management strategies for the phytosanitary pest, FCM in South African citrus. , Thesis (MSc) -- Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10
Quantifying the ecological and socioeconomic implications of a recovery/collapse of South Africa’s West Coast rock lobster fishery
- Authors: Eggers, Jessica Marguerite
- Date: 2021-10
- Subjects: Jasus lalandii South Africa , Lobster fisheries South Africa , Lobster fisheries Catch effort South Africa , Fishery management South Africa , Small-scale fisheries South Africa , Economics Sociological aspects , Value chain analysis
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/10962/188854 , vital:44792
- Description: The West Coast rock lobster (WCRL) Jasus lalandii fishery is South Africa’s third most valuable fishery, but the stock is currently at less than 2% of its pristine biomass. Scientists are warning that if no measures are taken, the WCRL could face commercial extinction. The necessary reductions in the global Total allowable Catch (TAC) seen in past years have had large economic implications for the WCRL value chain, but research into the socio-economic aspects of this fishery is limited. This study, therefore, aims to establish an overview of the economic revenue over the seasons 2016/17 – 2018/19 by exploring changes and trends in the net seasonal income (NSI) for the fishery, sectors within the fishery and different stakeholders. It also investigates the prospects for the sectors and different actors in this fishery over the seasons 2019/2020 - 2030/31 through analysis of the net present value (NPV) under three proposed global TAC management scenarios (global TAC of 640 tonnes, 1084 tonnes and 1280 tonnes). Data concerning costs and incomes as well as dynamics, mechanisms and concerns surrounding the fishery were collected from stakeholders in the different sectors through interviews and surveys. Further, official records from DEFF (catches, actors, vessels and quotas) and projections made by the Marine Resource Assessment (MARAM) team at the University of Cape Town (rates of recovery of the resource and future catches under the different TAC scenarios) were obtained and analysed. Cost and income data were summarised and models characterising the economic flows within the fishery were created. Calculations regarding the NSI and NPV were made using Monte Carlo simulations to account for the uncertainty surrounding many of the input variables. Results show that while the fishery as a whole made economic profits for the three seasons, the decreasing quotas in 2018/19 had a disproportionately negative impact on some of the representative individuals examined within the different sectors. The projections indicate that while each of the sectors as a whole would continue to make profits largely proportional to their allocation under the different TAC scenarios, many vessel owners in the fishery are likely to face economic losses or very marginal gains under the lower quota options, while the NPV for quota holders who outsource the catching of their quota are likely to be proportionally less affected by the changes in global TAC. This dynamic is important to consider for the future of this fishery. If the resource is to recover, and fishing activity is to continue equitably under the decreased quotas that the recovery of the biomass necessitates, the socio-economic context and the dynamics within which the fishers operate must be considered and studied more extensively and socio-economic consequences of a lower global TAC mitigated while improving the ecological status of the resource. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Eggers, Jessica Marguerite
- Date: 2021-10
- Subjects: Jasus lalandii South Africa , Lobster fisheries South Africa , Lobster fisheries Catch effort South Africa , Fishery management South Africa , Small-scale fisheries South Africa , Economics Sociological aspects , Value chain analysis
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/10962/188854 , vital:44792
- Description: The West Coast rock lobster (WCRL) Jasus lalandii fishery is South Africa’s third most valuable fishery, but the stock is currently at less than 2% of its pristine biomass. Scientists are warning that if no measures are taken, the WCRL could face commercial extinction. The necessary reductions in the global Total allowable Catch (TAC) seen in past years have had large economic implications for the WCRL value chain, but research into the socio-economic aspects of this fishery is limited. This study, therefore, aims to establish an overview of the economic revenue over the seasons 2016/17 – 2018/19 by exploring changes and trends in the net seasonal income (NSI) for the fishery, sectors within the fishery and different stakeholders. It also investigates the prospects for the sectors and different actors in this fishery over the seasons 2019/2020 - 2030/31 through analysis of the net present value (NPV) under three proposed global TAC management scenarios (global TAC of 640 tonnes, 1084 tonnes and 1280 tonnes). Data concerning costs and incomes as well as dynamics, mechanisms and concerns surrounding the fishery were collected from stakeholders in the different sectors through interviews and surveys. Further, official records from DEFF (catches, actors, vessels and quotas) and projections made by the Marine Resource Assessment (MARAM) team at the University of Cape Town (rates of recovery of the resource and future catches under the different TAC scenarios) were obtained and analysed. Cost and income data were summarised and models characterising the economic flows within the fishery were created. Calculations regarding the NSI and NPV were made using Monte Carlo simulations to account for the uncertainty surrounding many of the input variables. Results show that while the fishery as a whole made economic profits for the three seasons, the decreasing quotas in 2018/19 had a disproportionately negative impact on some of the representative individuals examined within the different sectors. The projections indicate that while each of the sectors as a whole would continue to make profits largely proportional to their allocation under the different TAC scenarios, many vessel owners in the fishery are likely to face economic losses or very marginal gains under the lower quota options, while the NPV for quota holders who outsource the catching of their quota are likely to be proportionally less affected by the changes in global TAC. This dynamic is important to consider for the future of this fishery. If the resource is to recover, and fishing activity is to continue equitably under the decreased quotas that the recovery of the biomass necessitates, the socio-economic context and the dynamics within which the fishers operate must be considered and studied more extensively and socio-economic consequences of a lower global TAC mitigated while improving the ecological status of the resource. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-10
Self-inquiry: Comparing Plato and Patanjali
- Authors: Coughlan, Daniel Michael
- Date: 2021-10
- Subjects: Plato , Patañjali , Self , Identity (Philosophical concept) , Comparison (Philosophy) , Justification (Theory of knowledge)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190066 , vital:44960
- Description: At its most effective my research hopes to re-affirm the central value and importance of self-inquiry. That is, I hope to echo the familiar call of the wise to know thyself. Of the many mouths and temple walls that have lent authority to this precept there is perhaps no mouth more important than one’s own. To know thyself is the task and responsibility of the individual. In order to arrive at the point where I can re-affirm its value I explore the nature of self-inquiry with the help of Plato, Patanjali and a comparison between them. I propose two general senses in which we might understand self-inquiry and seek to bring out the core problems faced by each. We find an account of these two senses and the relationship between them in both Plato and Patanjali, so too, though less obviously, in the comparison between them. The comparison provides the opportunity for reflecting on the ground that it moves from and depends on, the common ground we assume between the two compared philosophers/ies. I contend that this ground is ultimately the comparer, one’s self. The consequence is that the comparative project and the project of self-inquiry both meet and are mutually beneficial. The three together; Plato, Patanjali, and the comparison between them help us account for nature of self-inquiry in helping us to better understand the relationship between the two senses in which we can come to understand and think about it. In the first sense, self-inquiry is cast as the examination of one’s life. In the second sense, we are invited to consider the possibility of an unmediated knowing of the examiner, an unmediated self-knowing. With a better understanding of what self-inquiry is I stand to conclude by re-affirming its value. , Thesis (MPhil) -- Faculty of Humanities, Philosophy, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Coughlan, Daniel Michael
- Date: 2021-10
- Subjects: Plato , Patañjali , Self , Identity (Philosophical concept) , Comparison (Philosophy) , Justification (Theory of knowledge)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190066 , vital:44960
- Description: At its most effective my research hopes to re-affirm the central value and importance of self-inquiry. That is, I hope to echo the familiar call of the wise to know thyself. Of the many mouths and temple walls that have lent authority to this precept there is perhaps no mouth more important than one’s own. To know thyself is the task and responsibility of the individual. In order to arrive at the point where I can re-affirm its value I explore the nature of self-inquiry with the help of Plato, Patanjali and a comparison between them. I propose two general senses in which we might understand self-inquiry and seek to bring out the core problems faced by each. We find an account of these two senses and the relationship between them in both Plato and Patanjali, so too, though less obviously, in the comparison between them. The comparison provides the opportunity for reflecting on the ground that it moves from and depends on, the common ground we assume between the two compared philosophers/ies. I contend that this ground is ultimately the comparer, one’s self. The consequence is that the comparative project and the project of self-inquiry both meet and are mutually beneficial. The three together; Plato, Patanjali, and the comparison between them help us account for nature of self-inquiry in helping us to better understand the relationship between the two senses in which we can come to understand and think about it. In the first sense, self-inquiry is cast as the examination of one’s life. In the second sense, we are invited to consider the possibility of an unmediated knowing of the examiner, an unmediated self-knowing. With a better understanding of what self-inquiry is I stand to conclude by re-affirming its value. , Thesis (MPhil) -- Faculty of Humanities, Philosophy, 2021
- Full Text:
- Date Issued: 2021-10
The factors to be considered by the competition authorities when a fine may cause the firm to exit
- Authors: Quilliam, Layne Edwin
- Date: 2021-10
- Subjects: South Africa. Competition Act, 1998 , Competition Tribunal (South Africa) , Business enterprises Law and legislation South Africa , Debt-to-equity ratio South Africa , Bankruptcy Prevention , Causation , Competition
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/10962/188408 , vital:44751
- Description: The Competition Act empowers the Competition Tribunal to levy fines against a firm for certain contraventions of the Act. Such fines are statutorily capped to prevent the fine from causing the firm’s exit. This maximum is based on the overarching principle of fairness which precludes a fine, on its own, from destroying a firm’s business. However, the Competition Appeal Court acknowledged in 2013 that fines below this cap may still cause a firm to exit. The purpose of this paper is to propose the factors that should be considered when determining a firm’s ability to pay such a below-cap fine. These factors are the calculation of the fine, probable exit, causation of exit and the competitive effect of the firm’s exit. The fining provisions of the Act are initially explored to provide context for the discussion and are then compared to equivalent provisions in Europe. Liquidation and business rescue proceedings are then described as the most common forms of a firm’s exit from the market. Methods for determining the causal relationship between the fine and the firm’s exit are explored through delictual law’s factual and legal causation. The competitive effects of the firm’s exit are premised on the purpose of the Competition Act and are evaluated through the Competition Act’s merger provisions, specifically, the failing firm factor. These proposed factors are then tested through hypothetical facts to analyse their possible interactions and efficacy. , Thesis (LLM) -- Faculty of Law, Law, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Quilliam, Layne Edwin
- Date: 2021-10
- Subjects: South Africa. Competition Act, 1998 , Competition Tribunal (South Africa) , Business enterprises Law and legislation South Africa , Debt-to-equity ratio South Africa , Bankruptcy Prevention , Causation , Competition
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/10962/188408 , vital:44751
- Description: The Competition Act empowers the Competition Tribunal to levy fines against a firm for certain contraventions of the Act. Such fines are statutorily capped to prevent the fine from causing the firm’s exit. This maximum is based on the overarching principle of fairness which precludes a fine, on its own, from destroying a firm’s business. However, the Competition Appeal Court acknowledged in 2013 that fines below this cap may still cause a firm to exit. The purpose of this paper is to propose the factors that should be considered when determining a firm’s ability to pay such a below-cap fine. These factors are the calculation of the fine, probable exit, causation of exit and the competitive effect of the firm’s exit. The fining provisions of the Act are initially explored to provide context for the discussion and are then compared to equivalent provisions in Europe. Liquidation and business rescue proceedings are then described as the most common forms of a firm’s exit from the market. Methods for determining the causal relationship between the fine and the firm’s exit are explored through delictual law’s factual and legal causation. The competitive effects of the firm’s exit are premised on the purpose of the Competition Act and are evaluated through the Competition Act’s merger provisions, specifically, the failing firm factor. These proposed factors are then tested through hypothetical facts to analyse their possible interactions and efficacy. , Thesis (LLM) -- Faculty of Law, Law, 2021
- Full Text:
- Date Issued: 2021-10
The tuber-feeding weevil Listronotus frontalis as a candidate biological control agent for the invasive semi-aquatic plant Sagittaria platyphylla within South Africa
- Authors: Rogers, Daniel James
- Date: 2021-10
- Subjects: Listronotus South Africa , Arrowhead (Plants) South Africa , Arrowhead (Plants) Biological control South Africa , Invasive plants Biological control South Africa , Insects as biological pest control agents South Africa , Plant populations South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190731 , vital:45023
- Description: Sagittaria platyphylla (Engelm.) J.G.Sm. (Alismataceae) is an invasive, aquatic macrophyte originating in the southern United States of America. In South Africa, the plant was first detected in Krantzkloof Nature Reserve, KwaZulu-Natal Province in 2008, and due to its known impact in other countries, it was listed as a Category 1a invader species under the National Environmental Management: Biodiversity Act 2004 (NEM:BA). This invasive plant has proved difficult to manage due to its varied growth forms and reproductive strategies, such as prolific seed and below ground tuber production. Due to the limitations of conventional control mechanisms, biological control is currently being considered as a potential control option. The tuber feeding weevil Listronotus frontalis LeConte (Coleoptera: Curculionidae) has been identified as a candidate biological control agent for this invasive species. The aims of this study were twofold; to firstly determine the importance of tubers to S. platyphylla populations growing in South Africa; and secondly, to determine the biology and suitability of L. frontalis, a tuber feeder, as a candidate biological control agent. Surveys of S. platyphylla populations in South Africa showed that tubers were found in all sampled sites, except for Krantzkloof Nature reserve in KwaZulu-Natal Province. The highest number of tubers was 97.75 ± 10.62 (SE) m-2 recorded at Jonkershoek in the Western Cape Province. Monthly sampling from two sites in the Eastern Cape Province, the Makana Botanical Gardens and Maden Dam showed that neither season nor water depth affected tuber production. However, the mean number of tubers as well as mass of tubers sampled, were consistently higher (F(1,179) = 20.9542, P < 0.0001) and heavier (F(1, 857) = 585.7293, P < 0.0001) at the Botanical Gardens than at Maden Dam, respectively. The study showed that tubers are an important life stage of S. platyphylla populations and may vary in size and abundance between and within sites. The tuber feeding weevil was shown to develop from egg to ovipositing adult within just over 40 days. Females were recorded to lay up to 48 eggs within a period of one week. Impact studies showed that adult feeding led to a reduction in all but one of the 11 measured plant growth and developmental measurements, including a reduction in the mean mass of the above-ground plant material (F(2,2743) = 12.05, P = 0.002) as well as a reduction in size and abundance of tubers (F(2,58.47) = 9.756, P = 0.0006) and stolons(F(14.943) = 8.7577, P = 0.003). These results are encouraging and suggest that if the insect is released in South Africa, it may prove to be a valuable biocontrol agent. It is concluded that, until suitable biological control options become available in South Africa, the chemical and mechanical control measures currently implemented should continue, however, controlling tubers should be considered during the planning and implementation of these strategies. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Rogers, Daniel James
- Date: 2021-10
- Subjects: Listronotus South Africa , Arrowhead (Plants) South Africa , Arrowhead (Plants) Biological control South Africa , Invasive plants Biological control South Africa , Insects as biological pest control agents South Africa , Plant populations South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190731 , vital:45023
- Description: Sagittaria platyphylla (Engelm.) J.G.Sm. (Alismataceae) is an invasive, aquatic macrophyte originating in the southern United States of America. In South Africa, the plant was first detected in Krantzkloof Nature Reserve, KwaZulu-Natal Province in 2008, and due to its known impact in other countries, it was listed as a Category 1a invader species under the National Environmental Management: Biodiversity Act 2004 (NEM:BA). This invasive plant has proved difficult to manage due to its varied growth forms and reproductive strategies, such as prolific seed and below ground tuber production. Due to the limitations of conventional control mechanisms, biological control is currently being considered as a potential control option. The tuber feeding weevil Listronotus frontalis LeConte (Coleoptera: Curculionidae) has been identified as a candidate biological control agent for this invasive species. The aims of this study were twofold; to firstly determine the importance of tubers to S. platyphylla populations growing in South Africa; and secondly, to determine the biology and suitability of L. frontalis, a tuber feeder, as a candidate biological control agent. Surveys of S. platyphylla populations in South Africa showed that tubers were found in all sampled sites, except for Krantzkloof Nature reserve in KwaZulu-Natal Province. The highest number of tubers was 97.75 ± 10.62 (SE) m-2 recorded at Jonkershoek in the Western Cape Province. Monthly sampling from two sites in the Eastern Cape Province, the Makana Botanical Gardens and Maden Dam showed that neither season nor water depth affected tuber production. However, the mean number of tubers as well as mass of tubers sampled, were consistently higher (F(1,179) = 20.9542, P < 0.0001) and heavier (F(1, 857) = 585.7293, P < 0.0001) at the Botanical Gardens than at Maden Dam, respectively. The study showed that tubers are an important life stage of S. platyphylla populations and may vary in size and abundance between and within sites. The tuber feeding weevil was shown to develop from egg to ovipositing adult within just over 40 days. Females were recorded to lay up to 48 eggs within a period of one week. Impact studies showed that adult feeding led to a reduction in all but one of the 11 measured plant growth and developmental measurements, including a reduction in the mean mass of the above-ground plant material (F(2,2743) = 12.05, P = 0.002) as well as a reduction in size and abundance of tubers (F(2,58.47) = 9.756, P = 0.0006) and stolons(F(14.943) = 8.7577, P = 0.003). These results are encouraging and suggest that if the insect is released in South Africa, it may prove to be a valuable biocontrol agent. It is concluded that, until suitable biological control options become available in South Africa, the chemical and mechanical control measures currently implemented should continue, however, controlling tubers should be considered during the planning and implementation of these strategies. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10
Towards Reconfiguring the Agricultural Expert System (AES) for Black Small to Medium Farmer Development for Commercialization: A progressively focused policy literature review and social learning dialogue in the Eastern Cape Raymond Mhlaba Local Municipality
- Authors: Maqwelane, Lwanda
- Date: 2021-10
- Subjects: Farms, Small South Africa Amathole District Municipality , Minority farmers , Public-private sector cooperation South Africa Amathole District Municipality , Social learning South Africa Amathole District Municipality , Agricultural expert system (AES) , Black small to medium farmers (BSMF)
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/10962/188876 , vital:44794
- Description: This study focuses on the agricultural expert system (AES), its inherited and potential reframing capabilities for the development, growth and transition of black small to medium farmers (BSMF) into the commercial sector. The study was conducted as a critical analytical policy review of implemented policies pre-and post 1994 that subsequently highlighted the thematic continuities and discontinuities of policy reform and the subsequent impact on BSMFs using the AES as a conceptual lens. The study aimed working with stakeholders in the AES in the Raymond Mhlaba Local Municipality as a case study to critically engage and question the AES and its contemporary framing and potential reframing and continued impact on the BSMFs development. This was conducted through a dialogical social learning process in partnership with diverse voices that cut across the contemporary agrarian landscape that included “universities, think tanks, vocational training providers, standards-setting agencies, trade associations that provide specialized training, education, information, research and technical support” (Porter, 2000, p.17). The data for the social learning dialogue process was generated through an iterative analysis of dialogical social learning workshops, focus groups and semi-structured interviews. The analysis focused on the framing (Chapters 2, 3, and 5) and reframing of the AES (Chapter 6). Through dynamic engagement within the knowledge hub (contextual social learning and literature), the study surfaces a potential alternative discourse that actively includes the BSMFs as a crucial component of the commercial sector AES as the analysis shows these are largely excluded. This alternative discourse occurred through dialogical interactions with all participants via a pro-actively constituted social learning process, enriched and deepened by literature as indicated above. Main recommendations of the study are: 1. The AES must be framed to address the holistic value chain of BSMFs to help address underlying policy dualism, 2. Public Private Partnerships are needed to support BSMFs development and these should adopt a social learning approach that is reflective of complex realities 3. There is need for better understanding of roles and contributions of stakeholders in the AES to avoid duplications. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Maqwelane, Lwanda
- Date: 2021-10
- Subjects: Farms, Small South Africa Amathole District Municipality , Minority farmers , Public-private sector cooperation South Africa Amathole District Municipality , Social learning South Africa Amathole District Municipality , Agricultural expert system (AES) , Black small to medium farmers (BSMF)
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/10962/188876 , vital:44794
- Description: This study focuses on the agricultural expert system (AES), its inherited and potential reframing capabilities for the development, growth and transition of black small to medium farmers (BSMF) into the commercial sector. The study was conducted as a critical analytical policy review of implemented policies pre-and post 1994 that subsequently highlighted the thematic continuities and discontinuities of policy reform and the subsequent impact on BSMFs using the AES as a conceptual lens. The study aimed working with stakeholders in the AES in the Raymond Mhlaba Local Municipality as a case study to critically engage and question the AES and its contemporary framing and potential reframing and continued impact on the BSMFs development. This was conducted through a dialogical social learning process in partnership with diverse voices that cut across the contemporary agrarian landscape that included “universities, think tanks, vocational training providers, standards-setting agencies, trade associations that provide specialized training, education, information, research and technical support” (Porter, 2000, p.17). The data for the social learning dialogue process was generated through an iterative analysis of dialogical social learning workshops, focus groups and semi-structured interviews. The analysis focused on the framing (Chapters 2, 3, and 5) and reframing of the AES (Chapter 6). Through dynamic engagement within the knowledge hub (contextual social learning and literature), the study surfaces a potential alternative discourse that actively includes the BSMFs as a crucial component of the commercial sector AES as the analysis shows these are largely excluded. This alternative discourse occurred through dialogical interactions with all participants via a pro-actively constituted social learning process, enriched and deepened by literature as indicated above. Main recommendations of the study are: 1. The AES must be framed to address the holistic value chain of BSMFs to help address underlying policy dualism, 2. Public Private Partnerships are needed to support BSMFs development and these should adopt a social learning approach that is reflective of complex realities 3. There is need for better understanding of roles and contributions of stakeholders in the AES to avoid duplications. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10
An assessment of the wild cyclopia subternata (vleitee) resource
- Authors: Van der Walt, Wouter
- Date: 2021-04
- Subjects: Legumes -- South Africa , Fynbos -- South Africa , Fynbos ecology -- South Africa , Fynbos -- Harvesting -- South Africa , Biodiversity conservation -- South Africa , Traditional ecological knowledge -- South Africa , Wild Cyclopia Subternata (Vleitee) , Honeybush tea industry
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176874 , vital:42767
- Description: Cyclopia spp. is used for the production of Honeybush tea, an herbal tea which is used in many cases as a substitute for rooibos tea. The wild harvesting of this fynbos plant still brings in up to 85% of the annual crop and as such needs to be carefully monitored in order to avoid over harvesting and the destruction of biodiversity within the Eastern and Western Cape mountain regions of Southern Africa. Due to the concerns of overharvesting and unsuitable use of the wild resource issues of supply security have been raised. There is a lack of formal knowledge relating to the plant, its harvesting, the industry and its economic potential. This study aimed to amend this scarcity by contributing to the knowledge of C. subternata as a wild harvested plant, the physical environment favoured by C. subternata, sustainable use through harvesting of the wild plant and harvesting methods specific to this honeybush species. The research concludes by presenting a guideline for best harvest practices of the wild C. subternata plant. , Thesis (MSc) -- Faculty of Science, Department of Geography, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Van der Walt, Wouter
- Date: 2021-04
- Subjects: Legumes -- South Africa , Fynbos -- South Africa , Fynbos ecology -- South Africa , Fynbos -- Harvesting -- South Africa , Biodiversity conservation -- South Africa , Traditional ecological knowledge -- South Africa , Wild Cyclopia Subternata (Vleitee) , Honeybush tea industry
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176874 , vital:42767
- Description: Cyclopia spp. is used for the production of Honeybush tea, an herbal tea which is used in many cases as a substitute for rooibos tea. The wild harvesting of this fynbos plant still brings in up to 85% of the annual crop and as such needs to be carefully monitored in order to avoid over harvesting and the destruction of biodiversity within the Eastern and Western Cape mountain regions of Southern Africa. Due to the concerns of overharvesting and unsuitable use of the wild resource issues of supply security have been raised. There is a lack of formal knowledge relating to the plant, its harvesting, the industry and its economic potential. This study aimed to amend this scarcity by contributing to the knowledge of C. subternata as a wild harvested plant, the physical environment favoured by C. subternata, sustainable use through harvesting of the wild plant and harvesting methods specific to this honeybush species. The research concludes by presenting a guideline for best harvest practices of the wild C. subternata plant. , Thesis (MSc) -- Faculty of Science, Department of Geography, 2021
- Full Text:
- Date Issued: 2021-04
Investigating the factors that influence use of ICTs for citizen engagement in Malawi
- Authors: Sibande, Rachel Chavula
- Date: 2021-04
- Subjects: Information technology -- Malawi , Political participation -- Malawi , Mobile apps -- Malawi , UTAUT , Mzinda
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177019 , vital:42782 , 10.21504/10962/177019
- Description: Literature has suggested that Malawians are keen to participate. Malawian’s willingness to participate is evident as the country has recorded high voter turnouts during the elections in recent decades. However, literature also suggests that there is minimal citizen engagement in between elections. Elsewhere, Information and Communication Technologies (ICTs) have been used to enhance citizen engagement, but ICT led citizen engagement is still an emerging field and yet to be explored as an area of research particularly in Malawi. We thus sought to explore if the use of ICTs could improve citizen engagement with councils, councilors, and utility companies that provide water and electricity in Malawi. We developed and deployed an ICT platform called Mzinda which means My location in Malawi’s populous Chichewa language. The platform provided various channels for citizens and duty bearers to engage via SMS, USSD, web and a mobile application. We sought to understand the factors that influence citizen’s behavior intention to use an ICT platform to engage. We applied the modified UTAUT model by including Attitude and Self Efficacy social constructs that have among others been cited as limitations of the UTAUT model. We conducted factor loadings of six social constructs of the modified UTAUT model to validate content and reexamine the model in the context of citizen engagement using ICTs in Malawi. We found that, Attitude and Self Efficacy were not significant determinants of the Behaviour Intention for citizens to use the ICT platform. However, 75% of the Behaviour Intention was influenced by Perfomance Expectancy and Effort Expectancy as moderated by age and gender. Empirical evidence showed that responsiveness and actionability of councils and councillors had improved. We also learned that citizens believed that service delivery had improved and that they had more influence over councils, councillors, and the utility companies because of using the ICT platform. We conclude by noting that improvements in service delivery; enhanced responsiveness and actionability of councils, councillors and the utility companies were not necessarily as a result of the ICT platform alone; but a combination of ICTs and non-technology mechanisms of engaging the stakeholders through community campaigns, radio programs, print media engagement, community meetings and debates among others. It is evident that ICTs are not the panacea of all citizen engagement problems. This research can be useful to researchers and practitioners in the technology and citizen engagement domains. , Thesis (MSc) -- Faculty of Science, Department of Computer Science, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Sibande, Rachel Chavula
- Date: 2021-04
- Subjects: Information technology -- Malawi , Political participation -- Malawi , Mobile apps -- Malawi , UTAUT , Mzinda
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177019 , vital:42782 , 10.21504/10962/177019
- Description: Literature has suggested that Malawians are keen to participate. Malawian’s willingness to participate is evident as the country has recorded high voter turnouts during the elections in recent decades. However, literature also suggests that there is minimal citizen engagement in between elections. Elsewhere, Information and Communication Technologies (ICTs) have been used to enhance citizen engagement, but ICT led citizen engagement is still an emerging field and yet to be explored as an area of research particularly in Malawi. We thus sought to explore if the use of ICTs could improve citizen engagement with councils, councilors, and utility companies that provide water and electricity in Malawi. We developed and deployed an ICT platform called Mzinda which means My location in Malawi’s populous Chichewa language. The platform provided various channels for citizens and duty bearers to engage via SMS, USSD, web and a mobile application. We sought to understand the factors that influence citizen’s behavior intention to use an ICT platform to engage. We applied the modified UTAUT model by including Attitude and Self Efficacy social constructs that have among others been cited as limitations of the UTAUT model. We conducted factor loadings of six social constructs of the modified UTAUT model to validate content and reexamine the model in the context of citizen engagement using ICTs in Malawi. We found that, Attitude and Self Efficacy were not significant determinants of the Behaviour Intention for citizens to use the ICT platform. However, 75% of the Behaviour Intention was influenced by Perfomance Expectancy and Effort Expectancy as moderated by age and gender. Empirical evidence showed that responsiveness and actionability of councils and councillors had improved. We also learned that citizens believed that service delivery had improved and that they had more influence over councils, councillors, and the utility companies because of using the ICT platform. We conclude by noting that improvements in service delivery; enhanced responsiveness and actionability of councils, councillors and the utility companies were not necessarily as a result of the ICT platform alone; but a combination of ICTs and non-technology mechanisms of engaging the stakeholders through community campaigns, radio programs, print media engagement, community meetings and debates among others. It is evident that ICTs are not the panacea of all citizen engagement problems. This research can be useful to researchers and practitioners in the technology and citizen engagement domains. , Thesis (MSc) -- Faculty of Science, Department of Computer Science, 2021
- Full Text:
- Date Issued: 2021-04
Observations of cosmic re-ionisation with the Hydrogen Epoch of Reionization Array: simulations of closure phase spectra
- Authors: Charles, Ntsikelelo
- Date: 2021-04
- Subjects: Epoch of reionization , Space interferometry , Astronomy -- Observations , Closure phase spectra
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/174470 , vital:42480
- Description: The 21 cm transition from neutral Hydrogen promises to be the best observational probe of the Epoch of Reionisation. It has driven the construction of the new generation of low frequency radio interferometric arrays, including the Hydrogen Epoch of Reionization Array (HERA). The main difficulty in measuring the 21 cm signal is the presence of bright foregrounds that require very accurate interferometric calibration. Thyagarajan et al. (2018) proposed the use of closure phase quantities as a means to detect the 21 cm signal, which has the advantage of being independent (to first order) from calibration errors and therefore, bypasses the need for accurate calibration. Closure phases are, however, affected by so-called direction dependent effects, e.g. the fact that the dishes - or antennas - of an interferometric array are not identical to each other and , therefore, yield different antenna primary beam responses. In this thesis, we investigate the impact of direction dependent effects on closure quantities and simulate the impact that primary antenna beams affected by mutual coupling have on the foreground closure phase and its power spectrum i.e. the power spectrum of the bispectrum phase (Thyagarajan et al., 2020). Our simulations show that primary beams affected by mutual coupling lead to an overall leakage of foreground power in the so-called EoR window, i.e. power from smooth-spectrum foregrounds is confined to low k modes. We quantified this effect and found that the leakage is up to ~ 8 orders magnitude higher than the case of an ideal beam at kǁ > 0:5 h Mpc-1. We also found that the foreground leakage is worse when edge antennas are included, as they have a more different primary beam compared to antennas at the centre of the array. The leakage magnitude is worse when bright foregrounds appear in the antenna sidelobes, as expected. Our simulations provide a useful framework to interpret observations and assess which power spectrum region is expected to be most contaminated by foreground power leakage.
- Full Text:
- Date Issued: 2021-04
- Authors: Charles, Ntsikelelo
- Date: 2021-04
- Subjects: Epoch of reionization , Space interferometry , Astronomy -- Observations , Closure phase spectra
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/174470 , vital:42480
- Description: The 21 cm transition from neutral Hydrogen promises to be the best observational probe of the Epoch of Reionisation. It has driven the construction of the new generation of low frequency radio interferometric arrays, including the Hydrogen Epoch of Reionization Array (HERA). The main difficulty in measuring the 21 cm signal is the presence of bright foregrounds that require very accurate interferometric calibration. Thyagarajan et al. (2018) proposed the use of closure phase quantities as a means to detect the 21 cm signal, which has the advantage of being independent (to first order) from calibration errors and therefore, bypasses the need for accurate calibration. Closure phases are, however, affected by so-called direction dependent effects, e.g. the fact that the dishes - or antennas - of an interferometric array are not identical to each other and , therefore, yield different antenna primary beam responses. In this thesis, we investigate the impact of direction dependent effects on closure quantities and simulate the impact that primary antenna beams affected by mutual coupling have on the foreground closure phase and its power spectrum i.e. the power spectrum of the bispectrum phase (Thyagarajan et al., 2020). Our simulations show that primary beams affected by mutual coupling lead to an overall leakage of foreground power in the so-called EoR window, i.e. power from smooth-spectrum foregrounds is confined to low k modes. We quantified this effect and found that the leakage is up to ~ 8 orders magnitude higher than the case of an ideal beam at kǁ > 0:5 h Mpc-1. We also found that the foreground leakage is worse when edge antennas are included, as they have a more different primary beam compared to antennas at the centre of the array. The leakage magnitude is worse when bright foregrounds appear in the antenna sidelobes, as expected. Our simulations provide a useful framework to interpret observations and assess which power spectrum region is expected to be most contaminated by foreground power leakage.
- Full Text:
- Date Issued: 2021-04