Social upgrading or dependency?: Investigating the implications of the inclusion of commercial wine farms within South African Fairtrade certification
- Authors: Bell, Joshua
- Date: 2022-10-14
- Subjects: Competition, Unfair South Africa , Wine industry South Africa Employees , Unfair labor practices South Africa , Fairtrade International , International trade , Economic development Moral and ethical aspects South Africa , Wine industry Moral and ethical aspects South Africa , Work environment South Africa
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/327155 , vital:61086 , DOI 10.21504/10962/327155
- Description: The South African wine industry is one of the oldest sectors of the country’s economy, beginning in the early years of South African colonialism in the 17th century through the use of slave and slave-like labour. As an industry that has been defined by farm paternalism and dependency, the South African wine industry has had to demonstrate changes from its history of extreme racial and gendered exploitation to an industry that reflects the democratic values of a new South Africa. Ethical certifications are considered one way through which the post-apartheid South African wine industry can demonstrate that it has moved away from its historical practices and is now characterised by practices of decent work and social transformation. An important certificatory label that allows local wine producers entry into global wine production networks is Fairtrade International. While Fairtrade certification is often reserved for small-scale producers, this certification has been extended to large-scale, commercial producers within the South African wine industry despite its history of farm paternalism and dependency. This research asks if this inclusion promotes decent work through social upgrading or if it offers a platform for the continuation of farm dependency under the guise of ‘Fairtrade’. In this study, social upgrading has been defined through a ‘bottom-up’ approach that prioritises workers’ independence as a key means of improvement. Four key pillars are applied as embodying the concept of social upgrading: regular employment with set working hours; legally enforceable worker rights; social protection through collective and individual bargaining power; and non-discriminatory social dialogue that promotes significant socio-economic progression. A key finding of this research is that practices of dependency and paternalism continue on some large-scale commercial farms, despite their Fairtrade certification. Furthermore, the findings suggest that the benefits that farmworkers receive lock farmworkers into their position on the farm with marginally improved conditions and cease if workers depart from the Fairtrade wine farm. This suggests that, at best, this inclusion of commercial farmers within Fairtrade certification appears to create a top-down form of social upgrading that locks farmworkers into their position on the farm with marginally improved conditions and beneath a glass ceiling of development. At worst, this Fairtrade inclusion facilitates a global poverty network through paternalism and dependency under the guise of ‘Fairtrade’. As a result, where meaningful, bottom-up social upgrading may occur on South African wine farms, the study suggests that this is despite the presence of Fairtrade and not a result of it. , Thesis (PhD) -- Faculty of Humanities, Political and Interntional Studies, 2022
- Full Text:
- Authors: Bell, Joshua
- Date: 2022-10-14
- Subjects: Competition, Unfair South Africa , Wine industry South Africa Employees , Unfair labor practices South Africa , Fairtrade International , International trade , Economic development Moral and ethical aspects South Africa , Wine industry Moral and ethical aspects South Africa , Work environment South Africa
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/327155 , vital:61086 , DOI 10.21504/10962/327155
- Description: The South African wine industry is one of the oldest sectors of the country’s economy, beginning in the early years of South African colonialism in the 17th century through the use of slave and slave-like labour. As an industry that has been defined by farm paternalism and dependency, the South African wine industry has had to demonstrate changes from its history of extreme racial and gendered exploitation to an industry that reflects the democratic values of a new South Africa. Ethical certifications are considered one way through which the post-apartheid South African wine industry can demonstrate that it has moved away from its historical practices and is now characterised by practices of decent work and social transformation. An important certificatory label that allows local wine producers entry into global wine production networks is Fairtrade International. While Fairtrade certification is often reserved for small-scale producers, this certification has been extended to large-scale, commercial producers within the South African wine industry despite its history of farm paternalism and dependency. This research asks if this inclusion promotes decent work through social upgrading or if it offers a platform for the continuation of farm dependency under the guise of ‘Fairtrade’. In this study, social upgrading has been defined through a ‘bottom-up’ approach that prioritises workers’ independence as a key means of improvement. Four key pillars are applied as embodying the concept of social upgrading: regular employment with set working hours; legally enforceable worker rights; social protection through collective and individual bargaining power; and non-discriminatory social dialogue that promotes significant socio-economic progression. A key finding of this research is that practices of dependency and paternalism continue on some large-scale commercial farms, despite their Fairtrade certification. Furthermore, the findings suggest that the benefits that farmworkers receive lock farmworkers into their position on the farm with marginally improved conditions and cease if workers depart from the Fairtrade wine farm. This suggests that, at best, this inclusion of commercial farmers within Fairtrade certification appears to create a top-down form of social upgrading that locks farmworkers into their position on the farm with marginally improved conditions and beneath a glass ceiling of development. At worst, this Fairtrade inclusion facilitates a global poverty network through paternalism and dependency under the guise of ‘Fairtrade’. As a result, where meaningful, bottom-up social upgrading may occur on South African wine farms, the study suggests that this is despite the presence of Fairtrade and not a result of it. , Thesis (PhD) -- Faculty of Humanities, Political and Interntional Studies, 2022
- Full Text:
Land expropriation without compensation: a study of constructions of the Parliamentary process in selected mainstream and “ground-up” media from 27 February – 12 August 2018
- Authors: Jacobs, Luzuko G
- Date: 2022-10
- Subjects: Discourse analysis , Communication Political aspects South Africa , Land reform Press coverage South Africa , Land reform Government policy South Africa , Communication in mass media , Frames (Sociology) South Africa , Journalism Political aspects South Africa , Moneyweb Holdings Ltd. , City Press (South Africa) , Afriforum (South Africa) , African Farmers’ Association of South Africa (AFASA)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/297807 , vital:57630 , DOI 10.21504/10962/297807
- Description: This study investigates the constructions of land expropriation without compensation (LEwC) in the discourses of two mainstream media, Moneyweb and City Press, and two ground-up platforms, Afriforum and the African Farmers’ Association of South Africa (AFASA). It follows the February 2018 adoption by Parliament, of LEwC as a policy to reorder the country’s unequal and racially bifurcated economy. The motivations for, and opposition to the policy locate land as ‘the issue’ in conquest and capitalism. How land is signified therefore, is important to the understandings of ‘restitution’ and/or ‘resolution’. The news platforms selected here are diverse: Moneyweb focuses on investments. City Press concerns itself with politics. Afriforum and AFASA are alternative sphericules linked to ethnically- polarised quotidian concerns with land as a key focus. Discourses are central to how citizens see and construct themselves and one another as subjects. As such, media frames can be connected to justice and inter-‘race’ complexities. This is a study of media influences in cultivating certain meanings and understandings of tenuous and fractious political situations characterised by inequality and interracial enmity. The thesis draws from the Epistemologies of the South as well as Marxism to constitute the locus of its enunciation of colonisation, liberal capitalism, land question, justice, ideology, discourse, and framing. This framework is geared towards emic understanding of interrelated local and global contexts of the land question. Conceptual clarity is key to the development of an emancipatory imagination. Qualitative framing analysis and critical discourse analysis are used in this study to examine a diachronic corpus of 124 articles from the four platforms covering 167-days, from the adoption of the LEwC motion through the initial round of public hearings. The findings suggest a strong influence of the structures of coloniality in discourses across a wide political spectrum. The frames and counter-frames in the four platforms are simultaneously divergent and similar. Some are reactionary and conservative, others are liberal-transformational and even radical-prefigurative. All however, orbit around abyssal, North-centric, liberal capitalist normativity as the centripetal centre. The study proposes rethinking of the land question, a radical exorcism from land discourses, of structures of coloniality of power, knowledge, and being. Their mobilisation, predominance and naturalisation in political communication is anti-transformation and helps keep Black South Africans to this day, under the heavy yoke of an oppressive colonial and Apartheid reality as perpetual economic slaves. , Thesis (PhD) -- Faculty of Humanities, Journalism and Media Studies, 2022
- Full Text:
- Authors: Jacobs, Luzuko G
- Date: 2022-10
- Subjects: Discourse analysis , Communication Political aspects South Africa , Land reform Press coverage South Africa , Land reform Government policy South Africa , Communication in mass media , Frames (Sociology) South Africa , Journalism Political aspects South Africa , Moneyweb Holdings Ltd. , City Press (South Africa) , Afriforum (South Africa) , African Farmers’ Association of South Africa (AFASA)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/297807 , vital:57630 , DOI 10.21504/10962/297807
- Description: This study investigates the constructions of land expropriation without compensation (LEwC) in the discourses of two mainstream media, Moneyweb and City Press, and two ground-up platforms, Afriforum and the African Farmers’ Association of South Africa (AFASA). It follows the February 2018 adoption by Parliament, of LEwC as a policy to reorder the country’s unequal and racially bifurcated economy. The motivations for, and opposition to the policy locate land as ‘the issue’ in conquest and capitalism. How land is signified therefore, is important to the understandings of ‘restitution’ and/or ‘resolution’. The news platforms selected here are diverse: Moneyweb focuses on investments. City Press concerns itself with politics. Afriforum and AFASA are alternative sphericules linked to ethnically- polarised quotidian concerns with land as a key focus. Discourses are central to how citizens see and construct themselves and one another as subjects. As such, media frames can be connected to justice and inter-‘race’ complexities. This is a study of media influences in cultivating certain meanings and understandings of tenuous and fractious political situations characterised by inequality and interracial enmity. The thesis draws from the Epistemologies of the South as well as Marxism to constitute the locus of its enunciation of colonisation, liberal capitalism, land question, justice, ideology, discourse, and framing. This framework is geared towards emic understanding of interrelated local and global contexts of the land question. Conceptual clarity is key to the development of an emancipatory imagination. Qualitative framing analysis and critical discourse analysis are used in this study to examine a diachronic corpus of 124 articles from the four platforms covering 167-days, from the adoption of the LEwC motion through the initial round of public hearings. The findings suggest a strong influence of the structures of coloniality in discourses across a wide political spectrum. The frames and counter-frames in the four platforms are simultaneously divergent and similar. Some are reactionary and conservative, others are liberal-transformational and even radical-prefigurative. All however, orbit around abyssal, North-centric, liberal capitalist normativity as the centripetal centre. The study proposes rethinking of the land question, a radical exorcism from land discourses, of structures of coloniality of power, knowledge, and being. Their mobilisation, predominance and naturalisation in political communication is anti-transformation and helps keep Black South Africans to this day, under the heavy yoke of an oppressive colonial and Apartheid reality as perpetual economic slaves. , Thesis (PhD) -- Faculty of Humanities, Journalism and Media Studies, 2022
- Full Text:
A compliance framework for IT governance adoption and use by state-owned entities in South Africa
- Authors: Nxozi, Monelo
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/419244 , vital:71628
- Description: Embargoed. Possible release date in early 2025. , Thesis (PhD) -- Faculty of Commerce, Information Systems, 2023
- Full Text:
- Authors: Nxozi, Monelo
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/419244 , vital:71628
- Description: Embargoed. Possible release date in early 2025. , Thesis (PhD) -- Faculty of Commerce, Information Systems, 2023
- Full Text:
The incorporation of GeoGebra as a visualisation tool to teach calculus in teacher education institutions: the Zambian case
- Authors: Kangwa, Lemmy
- Date: 2022-10-14
- Subjects: GeoGebra , Calculus Study and teaching (Secondary) Zambia , Visual learning
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/405470 , vital:70174 , DOI
- Description: This qualitative case study investigated teacher educators’ (lecturers) use of the dynamic mathematics software, GeoGebra, to teach calculus in three teacher education institutions (TEIs) in Zambia. Visualisation, a key characteristic of GeoGebra, is increasingly gaining recognition of playing a critical role in mathematics teaching and learning, especially in problem solving tasks. It is considered a powerful didactical tool for students to construct mental and physical representations that can enhance conceptual understanding of mathematics. GeoGebra is a visualisation tool that can be used for problem-oriented teaching and foster mathematical experiments and discoveries. GeoGebra’s inherent visualisation characteristics align well with the teaching of calculus, the mathematical domain of this study. The study (whose research methodology was underpinned by the interpretive paradigm) was undertaken with a broader goal of designing and implementing GeoGebra applets and instructional materials on various calculus topics. The study is located within the “Teaching and Learning Mathematics with GeoGebra (TLMG) project” – a project that involves mathematics teachers and lecturers in Zambia. The case in this study is the six mathematics lecturers who co-designed and used GeoGebra applets to teach derivatives and integrals to pre-service mathematics teachers in TEIs. The unit of analysis therefore is the six lecturers’ use of GeoGebra as a visualisation tool to teach calculus to enhance conceptual understanding, their perceptions and experiences of using GeoGebra and the enabling and constraining factors of using GeoGebra to teach and learn mathematics. The data for the study were video recordings of observations and interviews of lecturers. The data was analysed thematically and was guided and informed by an analytical framework adopted from the theory of constructivism – the umbrella theoretical framework of this study – and the models of Technological Pedagogical Content Knowledge (TPACK), and the Technology Acceptance Model (TAM). A detailed analysis of the lecturers’ interactions with the applets enabled me to gain insights into the participants’ experiences and perceptions of GeoGebra applets in the teaching and learning process. The findings of the study revealed that the visualisation characteristics of GeoGebra generally enhanced the conceptual understanding of calculus. It also revealed that adequate training, coupled with sufficient knowledge of the subject matter in calculus, were necessary for lecturers to use GeoGebra effectively, and that the lack of resources and expertise were major hindrances in the use of GeoGebra to teach mathematics in TEIs. It also revealed that there is a need to equip GeoGebra with other features that would make it more versatile, and suggested a teaching approach that would complement the use of conventional methods and GeoGebra to provide a link between abstract and concrete concepts of calculus. , Thesis (PhD) -- Faculty of Education, Education, 2022
- Full Text:
- Authors: Kangwa, Lemmy
- Date: 2022-10-14
- Subjects: GeoGebra , Calculus Study and teaching (Secondary) Zambia , Visual learning
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/405470 , vital:70174 , DOI
- Description: This qualitative case study investigated teacher educators’ (lecturers) use of the dynamic mathematics software, GeoGebra, to teach calculus in three teacher education institutions (TEIs) in Zambia. Visualisation, a key characteristic of GeoGebra, is increasingly gaining recognition of playing a critical role in mathematics teaching and learning, especially in problem solving tasks. It is considered a powerful didactical tool for students to construct mental and physical representations that can enhance conceptual understanding of mathematics. GeoGebra is a visualisation tool that can be used for problem-oriented teaching and foster mathematical experiments and discoveries. GeoGebra’s inherent visualisation characteristics align well with the teaching of calculus, the mathematical domain of this study. The study (whose research methodology was underpinned by the interpretive paradigm) was undertaken with a broader goal of designing and implementing GeoGebra applets and instructional materials on various calculus topics. The study is located within the “Teaching and Learning Mathematics with GeoGebra (TLMG) project” – a project that involves mathematics teachers and lecturers in Zambia. The case in this study is the six mathematics lecturers who co-designed and used GeoGebra applets to teach derivatives and integrals to pre-service mathematics teachers in TEIs. The unit of analysis therefore is the six lecturers’ use of GeoGebra as a visualisation tool to teach calculus to enhance conceptual understanding, their perceptions and experiences of using GeoGebra and the enabling and constraining factors of using GeoGebra to teach and learn mathematics. The data for the study were video recordings of observations and interviews of lecturers. The data was analysed thematically and was guided and informed by an analytical framework adopted from the theory of constructivism – the umbrella theoretical framework of this study – and the models of Technological Pedagogical Content Knowledge (TPACK), and the Technology Acceptance Model (TAM). A detailed analysis of the lecturers’ interactions with the applets enabled me to gain insights into the participants’ experiences and perceptions of GeoGebra applets in the teaching and learning process. The findings of the study revealed that the visualisation characteristics of GeoGebra generally enhanced the conceptual understanding of calculus. It also revealed that adequate training, coupled with sufficient knowledge of the subject matter in calculus, were necessary for lecturers to use GeoGebra effectively, and that the lack of resources and expertise were major hindrances in the use of GeoGebra to teach mathematics in TEIs. It also revealed that there is a need to equip GeoGebra with other features that would make it more versatile, and suggested a teaching approach that would complement the use of conventional methods and GeoGebra to provide a link between abstract and concrete concepts of calculus. , Thesis (PhD) -- Faculty of Education, Education, 2022
- Full Text:
Identification of novel compounds against Plasmodium falciparum Cytochrome bc1 Complex inhibiting the trans-membrane electron transfer pathway: an In Silico study
- Authors: Chebon, Lorna Jemosop
- Date: 2022-10-14
- Subjects: Malaria , Plasmodium falciparum , Molecular dynamics , Antimalarials , Molecules Models , Docking , Cytochromes , Drug resistance , Computer simulation , Drugs Computer-aided design , System analysis
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365666 , vital:65774 , DOI https://doi.org/10.21504/10962/365666
- Description: Malaria continues to be a burden globally with a myriad of challenges deterring eradication efforts. With most antimalarials facing drug resistance, such as atovaquone (ATQ), alternative compounds that can withstand resistance are warranted. The Plasmodium falciparum cytochrome b (PfCytb), a subunit of P. falciparum cytochrome bc1 complex, is a validated drug target. Structurally, cytochrome b, cytochrome c1, and iron sulphur protein (ISP) subunits form the catalytic domain of the protein complex having heme bL, heme bH and iron-sulphur [2FE-2S] cluster cofactors. These cofactos have redox centres to aid in the electron transfer (ET) process. These subunits promote ET mainly through the enzyme’s ubiquinol oxidation (Qo) and ubiquinone reduction (Qi) processes in the catalytic domain. ATQ drug has been used in the prevention and treatment of uncomplicated malaria by targeting PfCytb protein. Once the mitochondrial transmembrane ET pathway is inhibited, it causes a collapse in its membrane potential. Previously reported ATQ drug resistance has been associated with the point mutations Y268C, Y268N and Y268S. Thus, in finding alternatives to the ATQ drug, this research aimed to: i) employ in silico approaches incorporating protein into phospholipid bilayer for the first time to understand the parasites’ resistance mechanism; ii) determine any sequence and structural differences that could be explored in drug design studies; and iii) screen for PfCytb-iron sulphur protein (Cytb-ISP) hit compounds from South African natural compound database (SANCDB) and Medicines for Malaria Venture (MMV) that can withstand the identified mutations. Using computational tools, comparative sequence and structural analyses were performed on the cytochrome b protein, where the ultimate focus was on P. falciparum cytochrome b and its human homolog. Through multiple sequence alignment, motif discovery and phylogeny, differences between P. falciparum and H. sapiens cytochrome b were identified. Protein modelling of both P. falciparum and H. sapiens cytochrome b - iron sulphur protein (PfCytb-ISP and HsCytb-ISP) was performed. Results showed that at the sequence level, there were few amino acid residue differences because the protein is highly conserved. Important to note is the four-residue deletion in Plasmodium spp. absent in the human homolog. Motif analysis discovered five unique motifs in P. falciparum cytochrome b protein which were mapped onto the predicted protein model. These motifs were not in regions of functional importance; hence their function is still unknown. At a structural level, the four-residue deletion was observed to alter the Qo substrate binding pocket as reported in previous studies and confirmed in this study. This deletion resulted in a 0.83 Å structural displacement. Also, there are currently no in silico studies that have performed experiments with P. falciparum cytochrome b protein incorporated into a phospholipid bilayer. Using 350 ns molecular dynamics (MD) simulations of the holo and ATQ-bound systems, the study highlighted the resistance mechanism of the parasite protein where the loss of active site residue-residue interactions was identified, all linked to the three mutations. The identified compromised interactions are likely to destabilise the protein’s function, specifically in the Qo substrate binding site. This showed the possible effect of mutations on ATQ drug activity, where all three mutations were reported to share a similar resistance mechanism. Thereafter, this research work utilised in silico approaches where both Qo active site and interface pocket were targeted by screening the South African natural compounds database (SANCDB) and Medicines for Malaria Venture (MMV) compounds to identify novel selective hits. SANCDB compounds are known for their structural complexity that preserves the potency of the drug molecule. Both SANCDB and MMV compounds have not been explored as inhibitors against the PfCytb drug target. Molecular docking, molecular dynamics (MD) simulations, principal component, and dynamic residue network (DRN; global and local) analyses were utilised to identify and confirm the potential selective inhibitors. Docking results identified compounds that bound selectively onto PfCytb-ISP with a binding energy ≤ -8.7 kcal/mol-1. Further, this work validated a total of eight potential selective compounds to inhibit PfCytb-ISP protein (Qo active site) not only in the wild-type but also in the presence of the point mutations Y268C, Y268N and Y268S. The selective binding of these hit compounds could be linked to the differences reported at sequence/residue level in chapter 3. DRN and residue contact map analyses of the eight compounds in holo and ligand-bound systems revealed reduced residue interactions and decreased protein communication. This suggests that the eight compounds show the possibility of inhibiting the parasite and disrupting important residue-residue interactions. Additionally, 13 selective compounds were identified to bind at the protein’s heterodimer interface, where global and local analysis confirmed their effect on active site residues (distal location) as well as on the communication network. Based on the sequence differences between PfCytb and the human homolog, these findings suggest these selective compounds as potential allosteric modulators of the parasite enzyme, which may serve as possible replacements of the already resistant ATQ drug. Therefore, these findings pave the way for further in vitro studies to establish their anti-plasmodial inhibition levels. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Authors: Chebon, Lorna Jemosop
- Date: 2022-10-14
- Subjects: Malaria , Plasmodium falciparum , Molecular dynamics , Antimalarials , Molecules Models , Docking , Cytochromes , Drug resistance , Computer simulation , Drugs Computer-aided design , System analysis
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365666 , vital:65774 , DOI https://doi.org/10.21504/10962/365666
- Description: Malaria continues to be a burden globally with a myriad of challenges deterring eradication efforts. With most antimalarials facing drug resistance, such as atovaquone (ATQ), alternative compounds that can withstand resistance are warranted. The Plasmodium falciparum cytochrome b (PfCytb), a subunit of P. falciparum cytochrome bc1 complex, is a validated drug target. Structurally, cytochrome b, cytochrome c1, and iron sulphur protein (ISP) subunits form the catalytic domain of the protein complex having heme bL, heme bH and iron-sulphur [2FE-2S] cluster cofactors. These cofactos have redox centres to aid in the electron transfer (ET) process. These subunits promote ET mainly through the enzyme’s ubiquinol oxidation (Qo) and ubiquinone reduction (Qi) processes in the catalytic domain. ATQ drug has been used in the prevention and treatment of uncomplicated malaria by targeting PfCytb protein. Once the mitochondrial transmembrane ET pathway is inhibited, it causes a collapse in its membrane potential. Previously reported ATQ drug resistance has been associated with the point mutations Y268C, Y268N and Y268S. Thus, in finding alternatives to the ATQ drug, this research aimed to: i) employ in silico approaches incorporating protein into phospholipid bilayer for the first time to understand the parasites’ resistance mechanism; ii) determine any sequence and structural differences that could be explored in drug design studies; and iii) screen for PfCytb-iron sulphur protein (Cytb-ISP) hit compounds from South African natural compound database (SANCDB) and Medicines for Malaria Venture (MMV) that can withstand the identified mutations. Using computational tools, comparative sequence and structural analyses were performed on the cytochrome b protein, where the ultimate focus was on P. falciparum cytochrome b and its human homolog. Through multiple sequence alignment, motif discovery and phylogeny, differences between P. falciparum and H. sapiens cytochrome b were identified. Protein modelling of both P. falciparum and H. sapiens cytochrome b - iron sulphur protein (PfCytb-ISP and HsCytb-ISP) was performed. Results showed that at the sequence level, there were few amino acid residue differences because the protein is highly conserved. Important to note is the four-residue deletion in Plasmodium spp. absent in the human homolog. Motif analysis discovered five unique motifs in P. falciparum cytochrome b protein which were mapped onto the predicted protein model. These motifs were not in regions of functional importance; hence their function is still unknown. At a structural level, the four-residue deletion was observed to alter the Qo substrate binding pocket as reported in previous studies and confirmed in this study. This deletion resulted in a 0.83 Å structural displacement. Also, there are currently no in silico studies that have performed experiments with P. falciparum cytochrome b protein incorporated into a phospholipid bilayer. Using 350 ns molecular dynamics (MD) simulations of the holo and ATQ-bound systems, the study highlighted the resistance mechanism of the parasite protein where the loss of active site residue-residue interactions was identified, all linked to the three mutations. The identified compromised interactions are likely to destabilise the protein’s function, specifically in the Qo substrate binding site. This showed the possible effect of mutations on ATQ drug activity, where all three mutations were reported to share a similar resistance mechanism. Thereafter, this research work utilised in silico approaches where both Qo active site and interface pocket were targeted by screening the South African natural compounds database (SANCDB) and Medicines for Malaria Venture (MMV) compounds to identify novel selective hits. SANCDB compounds are known for their structural complexity that preserves the potency of the drug molecule. Both SANCDB and MMV compounds have not been explored as inhibitors against the PfCytb drug target. Molecular docking, molecular dynamics (MD) simulations, principal component, and dynamic residue network (DRN; global and local) analyses were utilised to identify and confirm the potential selective inhibitors. Docking results identified compounds that bound selectively onto PfCytb-ISP with a binding energy ≤ -8.7 kcal/mol-1. Further, this work validated a total of eight potential selective compounds to inhibit PfCytb-ISP protein (Qo active site) not only in the wild-type but also in the presence of the point mutations Y268C, Y268N and Y268S. The selective binding of these hit compounds could be linked to the differences reported at sequence/residue level in chapter 3. DRN and residue contact map analyses of the eight compounds in holo and ligand-bound systems revealed reduced residue interactions and decreased protein communication. This suggests that the eight compounds show the possibility of inhibiting the parasite and disrupting important residue-residue interactions. Additionally, 13 selective compounds were identified to bind at the protein’s heterodimer interface, where global and local analysis confirmed their effect on active site residues (distal location) as well as on the communication network. Based on the sequence differences between PfCytb and the human homolog, these findings suggest these selective compounds as potential allosteric modulators of the parasite enzyme, which may serve as possible replacements of the already resistant ATQ drug. Therefore, these findings pave the way for further in vitro studies to establish their anti-plasmodial inhibition levels. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
Mechanistic analysis of two cytotoxic thiazolidinones as novel inhibitors of Triple-Negative Breast Cancer
- Authors: Vukea, Nyeleti
- Date: 2022-10-14
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365734 , vital:65780
- Description: Thesis embargoes. Expected release date early 2025. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Authors: Vukea, Nyeleti
- Date: 2022-10-14
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365734 , vital:65780
- Description: Thesis embargoes. Expected release date early 2025. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
Don’t let the little man live in your head for free: an interpretive phenomenological analysis of seafarers with reportedly high levels of well-being
- Authors: Brown, Lauren Natalie
- Date: 2022-10-14
- Subjects: Seafaring life Psychological aspects , Sailors Mental health , Well-being , Phenomenology , Work environment
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/327653 , vital:61140 , DOI 10.21504/10962/327653
- Description: The mental health of seafarers has become a growing issue of concern and has attracted the attention of researchers in recent times. Seafarers are predominantly men, spend months at sea with little to no contact with loved ones ashore, and usually must reside in confined spaces that often contain substantial levels of noise and heat. The underlying causes of mental illness among seafarers are known. Some of the causes include sleep deprivation, occupational stress, marital/relationship problems, fatigue, the threat of piracy, psychosocial workload, loneliness, social isolation, separation from families, lack of shore leave, cultural issues, and job security. Despite these stressors, there are many men and women seafarers who flourish in the industry and enjoy their careers. Very little research has been conducted into the well-being practices of those seafarers who enjoy high levels of well-being. This study explores the lived experiences of a group of seafarers with reportedly high levels of psychological well-being, as well as their experiences of workplace stressors and mental health interventions offered by the industry. This study is an interpretive phenomenological analysis, which is epistemologically underpinned by phenomenology, hermeneutics and idiography. Results revealed four focus areas: general lived experiences across two worlds and how this relates to identity, what seafarers with reportedly high levels of psychological well-being experience as stressors, well-being practices of these seafarers and how these seafarers experience and make sense of mental health interventions they have come across. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2022
- Full Text:
- Authors: Brown, Lauren Natalie
- Date: 2022-10-14
- Subjects: Seafaring life Psychological aspects , Sailors Mental health , Well-being , Phenomenology , Work environment
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/327653 , vital:61140 , DOI 10.21504/10962/327653
- Description: The mental health of seafarers has become a growing issue of concern and has attracted the attention of researchers in recent times. Seafarers are predominantly men, spend months at sea with little to no contact with loved ones ashore, and usually must reside in confined spaces that often contain substantial levels of noise and heat. The underlying causes of mental illness among seafarers are known. Some of the causes include sleep deprivation, occupational stress, marital/relationship problems, fatigue, the threat of piracy, psychosocial workload, loneliness, social isolation, separation from families, lack of shore leave, cultural issues, and job security. Despite these stressors, there are many men and women seafarers who flourish in the industry and enjoy their careers. Very little research has been conducted into the well-being practices of those seafarers who enjoy high levels of well-being. This study explores the lived experiences of a group of seafarers with reportedly high levels of psychological well-being, as well as their experiences of workplace stressors and mental health interventions offered by the industry. This study is an interpretive phenomenological analysis, which is epistemologically underpinned by phenomenology, hermeneutics and idiography. Results revealed four focus areas: general lived experiences across two worlds and how this relates to identity, what seafarers with reportedly high levels of psychological well-being experience as stressors, well-being practices of these seafarers and how these seafarers experience and make sense of mental health interventions they have come across. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2022
- Full Text:
Synthesis and evaluation of the medicinal potential of novel 4-hydroxycoumarin derivatives
- Authors: Manyeruke, Meloddy Hlatini
- Date: 2022-04-08
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/164458 , vital:41120 , doi:10.21504/10962/164458
- Description: This research has focused on the synthesis and biological evaluation of a broad range of compounds characterised by the presence of the pharmacologically significant 4-hydroxycoumalin scaffold. The compounds were designed to contain additional pharmachophoric centres to enhance bioactivity and generate lead compounds with dualaction potential. The use of 4-hydroxycoumarin as the primary synthon enabled access to various series of 4-hydroxycoumarin conjugates, the reactive 3-position on the 4-hydroxycoumarin moiety being exploited for regioselective construction of the targeted compounds in several steps. Some of the reactants required in the construction of these compounds were specially synthesised and included propargyloxy benzaldehydes, benzyloxy benzaldehydes and 2,3-dihydroxysuccino-dihydride. Overall, eight different families of novel compounds were accessed, comprising conjugates of 4-hydroxycoumarin with bisethylidenesuccinohyrazide, trifluoroacetamide, amino, benzyloxyphenyl-iminoethyl, benzylidenehyrazinyl-thiazoyl, benzylidenehydrazonoethyl, propargyloxybenzylidenehydrazonoethyl and phenylacryloyl moieties using protocols that required minimal work-up and purification. The eighty novel compounds synthesised in the study were fully characterised using HMRS and advanced NMR techniques. Cytotoxicity, HIV-1 IN and PR inhibitory, and antitrypanosomal, antimalarial and anti-Mtb assays were conducted on the synthesised coumarin derivatives. Several compounds exhibited activity against HIV-1 IN, the most potent being a bis-ethylidenesuccinohyrazide with an IC50 value of 3.5 μM. Various compounds exhibited anti-malarial activity (% pLDH viability in the range 62-77%), anti-trypanosomal activity (the most potent with an IC50 = 0.9 μM against T.b. brucei) and a measure of anti-Mtb activity. Apart from two chalconyl derivatives, none of the synthesised compounds exhibited significant cytotoxicity. Conflicting results were obtained from the in silico docking studies; in some cases supporting the observed in vitro assay data while, in others, exhibiting no correlation. , Thesis (PhD) -- Faculty of Science, Chemistry, 2020
- Full Text:
- Authors: Manyeruke, Meloddy Hlatini
- Date: 2022-04-08
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/164458 , vital:41120 , doi:10.21504/10962/164458
- Description: This research has focused on the synthesis and biological evaluation of a broad range of compounds characterised by the presence of the pharmacologically significant 4-hydroxycoumalin scaffold. The compounds were designed to contain additional pharmachophoric centres to enhance bioactivity and generate lead compounds with dualaction potential. The use of 4-hydroxycoumarin as the primary synthon enabled access to various series of 4-hydroxycoumarin conjugates, the reactive 3-position on the 4-hydroxycoumarin moiety being exploited for regioselective construction of the targeted compounds in several steps. Some of the reactants required in the construction of these compounds were specially synthesised and included propargyloxy benzaldehydes, benzyloxy benzaldehydes and 2,3-dihydroxysuccino-dihydride. Overall, eight different families of novel compounds were accessed, comprising conjugates of 4-hydroxycoumarin with bisethylidenesuccinohyrazide, trifluoroacetamide, amino, benzyloxyphenyl-iminoethyl, benzylidenehyrazinyl-thiazoyl, benzylidenehydrazonoethyl, propargyloxybenzylidenehydrazonoethyl and phenylacryloyl moieties using protocols that required minimal work-up and purification. The eighty novel compounds synthesised in the study were fully characterised using HMRS and advanced NMR techniques. Cytotoxicity, HIV-1 IN and PR inhibitory, and antitrypanosomal, antimalarial and anti-Mtb assays were conducted on the synthesised coumarin derivatives. Several compounds exhibited activity against HIV-1 IN, the most potent being a bis-ethylidenesuccinohyrazide with an IC50 value of 3.5 μM. Various compounds exhibited anti-malarial activity (% pLDH viability in the range 62-77%), anti-trypanosomal activity (the most potent with an IC50 = 0.9 μM against T.b. brucei) and a measure of anti-Mtb activity. Apart from two chalconyl derivatives, none of the synthesised compounds exhibited significant cytotoxicity. Conflicting results were obtained from the in silico docking studies; in some cases supporting the observed in vitro assay data while, in others, exhibiting no correlation. , Thesis (PhD) -- Faculty of Science, Chemistry, 2020
- Full Text:
The fiction of scarcity: conceptualising scarcity in terms of global justice
- Authors: Brotherton, Michelle
- Date: 2022-04-07
- Subjects: Scarcity Philosophy , Distributive justice , Political science Philosophy , Philosophy , Justification (Ethics) , Fallacies (Logic)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294526 , vital:57229 , DOI https://dx.doi.org/10.21504/10962/294526
- Description: This thesis intends to contribute to the discourse on global justice as it pertains to resources, the distribution of resources, and the allocation of resources. The focus is on the concept of scarcity. I examine scarcity for how it is understood, interpreted, and applied in the literature on global justice. This thesis argues that scarcity lacks conceptual clarity in the discourse on global justice and argues that if scarcity is misconstrued, the consequences can be severe. Conceptual clarity is thus necessary to ensure that scarcity is properly referred to in the discourse on global justice so that scarcity is not erroneously used when justifications are sought for material deprivation and consequent human suffering. In the process, I will also examine how scarcity is used as a justification in instances of material deprivation and why this is problematic. Given the lack of conceptual clarity regarding scarcity, I argue that reliance on scarcity as justification may be erroneous. The conflation of absolute scarcity and relative scarcity may amount to a category mistake. This thesis purports to clarify scarcity conceptually in the context of global justice. In doing so, I recommend that a resource-centric approach to resource scarcity is adopted to accurately account for the scarcity status of resources. A resource-centric approach to resource scarcity based on a more nuanced understanding of scarcity avoids the potential category mistake. Such an approach ensures that material deprivation and consequent human suffering are not wrongfully attributed to scarcity. , Thesis (PhD) -- Faculty of Humanities, Philosophy, 2022
- Full Text:
- Authors: Brotherton, Michelle
- Date: 2022-04-07
- Subjects: Scarcity Philosophy , Distributive justice , Political science Philosophy , Philosophy , Justification (Ethics) , Fallacies (Logic)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294526 , vital:57229 , DOI https://dx.doi.org/10.21504/10962/294526
- Description: This thesis intends to contribute to the discourse on global justice as it pertains to resources, the distribution of resources, and the allocation of resources. The focus is on the concept of scarcity. I examine scarcity for how it is understood, interpreted, and applied in the literature on global justice. This thesis argues that scarcity lacks conceptual clarity in the discourse on global justice and argues that if scarcity is misconstrued, the consequences can be severe. Conceptual clarity is thus necessary to ensure that scarcity is properly referred to in the discourse on global justice so that scarcity is not erroneously used when justifications are sought for material deprivation and consequent human suffering. In the process, I will also examine how scarcity is used as a justification in instances of material deprivation and why this is problematic. Given the lack of conceptual clarity regarding scarcity, I argue that reliance on scarcity as justification may be erroneous. The conflation of absolute scarcity and relative scarcity may amount to a category mistake. This thesis purports to clarify scarcity conceptually in the context of global justice. In doing so, I recommend that a resource-centric approach to resource scarcity is adopted to accurately account for the scarcity status of resources. A resource-centric approach to resource scarcity based on a more nuanced understanding of scarcity avoids the potential category mistake. Such an approach ensures that material deprivation and consequent human suffering are not wrongfully attributed to scarcity. , Thesis (PhD) -- Faculty of Humanities, Philosophy, 2022
- Full Text:
The role of visualisation in redefining the pedagogy of fractions in mathematics classrooms among senior primary school teachers
- Authors: Ausiku, Charity Makwiliro
- Date: 2022-10-14
- Subjects: Mathematics Study and teaching (Elementary) Namibia , Fractions Study and teaching (Elementary) Namibia , Visualization , Visual learning , Dual-coding hypothesis , Constructivism (Education) Namibia
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/405456 , vital:70173 , DOI 10.21504/10962/405456
- Description: This mixed methods study explored the impact of the use of a visualisation approach on the pedagogy of eight teacher participants who were involved in the Rundu Campus Fraction Project (RCFP). The aim of this study was to determine the extent to which participants incorporated visualisation processes in the pedagogy of fractions, in view of their exposure to visualisation activities in the RCFP. Since fractions are difficult to teach and learn, visualisation was considered as an alternative approach to the pedagogy of fractions because it presents learners with opportunities to improve their proportional and spatial reasoning. This study was founded on the premise that the incorporation of both verbal and nonverbal cues can enhance the teaching and learning of fractions rather than the use of a single cue. Hence, the two theories underpinning this study are the Dual Coding Theory and the Constructivist Theory. While the Dual Coding Theory advocates for the use of verbal and nonverbal codes, the Constructivist theory states that meaningful learning occurs when learners are presented with opportunities to construct their own knowledge. Thus, the two codes are intertwined. In other words, the active construction of knowledge among learners is aided by using constructivist teaching approaches through the incorporation of both verbal and nonverbal codes. Although this study was predominantly qualitative, quantitative methods were also used in the data collection process. A questionnaire was administered to identify teacher participants for this study, based on their teaching orientations. Their views on best practices in mathematics classrooms in general and the incorporation of visualisation processes in particular, were instrumental in the selection of participants for this study. In addition, observations and semi-structured interviews were also used as research methods. Twenty-five lesson samples were video recorded, transcribed and analysed using both qualitative and quantitative methods. Moreover, each of the eight participants was exposed to a set of pre- and post-observation interviews during which they were expected to express their views on the selection, incorporation and impact of visualisation processes on the teaching of fractions. Data sets from all three instruments were analysed using both quantitative and qualitative methods. The findings indicate that the RCFP had an impact on the teaching strategies employed by the participants as they all incorporated visualisation processes into their teaching to some extent. In some lessons, the visual code was effectively blended into the verbal code while in others, the purpose of and connection between the two codes was not evident. Hence, although all the participants embraced the incorporation of visualisation in the pedagogy of mathematics, some of them struggled to find its rightful position in the teaching of fractions. The findings suggest that despite the participants’ eagerness to use visualisation in their fraction lessons, some of them did not have adequate knowledge to successfully merge it with the conventional verbal code. Thus, for the integration of visuals to be impactful, it should be carefully merged in the teaching of fractions by taking into account various factors. , Thesis (PhD) -- Faculty of Education, Education, 2022
- Full Text:
- Authors: Ausiku, Charity Makwiliro
- Date: 2022-10-14
- Subjects: Mathematics Study and teaching (Elementary) Namibia , Fractions Study and teaching (Elementary) Namibia , Visualization , Visual learning , Dual-coding hypothesis , Constructivism (Education) Namibia
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/405456 , vital:70173 , DOI 10.21504/10962/405456
- Description: This mixed methods study explored the impact of the use of a visualisation approach on the pedagogy of eight teacher participants who were involved in the Rundu Campus Fraction Project (RCFP). The aim of this study was to determine the extent to which participants incorporated visualisation processes in the pedagogy of fractions, in view of their exposure to visualisation activities in the RCFP. Since fractions are difficult to teach and learn, visualisation was considered as an alternative approach to the pedagogy of fractions because it presents learners with opportunities to improve their proportional and spatial reasoning. This study was founded on the premise that the incorporation of both verbal and nonverbal cues can enhance the teaching and learning of fractions rather than the use of a single cue. Hence, the two theories underpinning this study are the Dual Coding Theory and the Constructivist Theory. While the Dual Coding Theory advocates for the use of verbal and nonverbal codes, the Constructivist theory states that meaningful learning occurs when learners are presented with opportunities to construct their own knowledge. Thus, the two codes are intertwined. In other words, the active construction of knowledge among learners is aided by using constructivist teaching approaches through the incorporation of both verbal and nonverbal codes. Although this study was predominantly qualitative, quantitative methods were also used in the data collection process. A questionnaire was administered to identify teacher participants for this study, based on their teaching orientations. Their views on best practices in mathematics classrooms in general and the incorporation of visualisation processes in particular, were instrumental in the selection of participants for this study. In addition, observations and semi-structured interviews were also used as research methods. Twenty-five lesson samples were video recorded, transcribed and analysed using both qualitative and quantitative methods. Moreover, each of the eight participants was exposed to a set of pre- and post-observation interviews during which they were expected to express their views on the selection, incorporation and impact of visualisation processes on the teaching of fractions. Data sets from all three instruments were analysed using both quantitative and qualitative methods. The findings indicate that the RCFP had an impact on the teaching strategies employed by the participants as they all incorporated visualisation processes into their teaching to some extent. In some lessons, the visual code was effectively blended into the verbal code while in others, the purpose of and connection between the two codes was not evident. Hence, although all the participants embraced the incorporation of visualisation in the pedagogy of mathematics, some of them struggled to find its rightful position in the teaching of fractions. The findings suggest that despite the participants’ eagerness to use visualisation in their fraction lessons, some of them did not have adequate knowledge to successfully merge it with the conventional verbal code. Thus, for the integration of visuals to be impactful, it should be carefully merged in the teaching of fractions by taking into account various factors. , Thesis (PhD) -- Faculty of Education, Education, 2022
- Full Text:
With dreams in our hands: Towards transgressive knowledge-making cultures
- Authors: Knowles, Corinne Ruth
- Date: 2023-10-13
- Subjects: African feminism , Pedagogy , Political sociology , Knowledge, Theory of Political aspects , Transformative learning
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/402955 , vital:69909 , DOI 10.21504/10962/402955
- Description: Knowledge-making in universities is not neutral and takes different forms. This thesis critically examines the politics of knowledge to propose and present a transgressive schema for knowledge-making that is co-created with students. It emerges from teaching and learning encounters in the Humanities Extended Studies (ES) Programme at Rhodes University, where for the past decade we have experimented with different ways of knowledge-making that run counter to conventional pedagogic practices. We set up a project for the thesis that allowed us to work with knowledge in ways that are Afrocentric, and that hold and nurture our dreams. The theory and methodology of the project are explained in the first academic paper for this PhD by publication. The project and its derivatives use an African Feminist framing, and centre the ontoepistemologies of African young people who find themselves alienated and marginalised by a western bias in university curricula. Former ES student volunteers came up with topics, responded to them, reviewed each other’s work, and co-wrote two academic papers that demonstrate a praxis of African Feminist research and pedagogic principles. Two further projects practise the principles that emerge from the primary project, and together they have tested knowledge-making cultures that inspire critical thinking and creative humanity. These are explained in two further academic papers. One is co-written with the copresenter of an online inter-continental short course for PhD students on African Feminist Research Methodology. The other is single authored, and introduces the third project, a Political and International Studies third-year course on African Feminist theory. The schema for knowledge-making uses the hand, which holds our dream, as a descriptive metaphor. Each of the five fingers of the hand represents an aspect of how we have collaborated on the projects and in lecture rooms, and what this has taught us about how to nurture and inspire the dreams of young African people through transgressive knowledgemaking cultures. The five aspects – framing, activating, seeing, creating, imagining – are mutually constitutive elements of knowledge-making that are introduced throughout the thesis, and explained in careful detail in the conclusion as a synthesis of the collaborations. , Siphethe amaphupha ezandleni zethu: ukwenza iinckubeko zolwazi ezigxile ekuphazamiseni isiqhelo Isishwankathelo Ukwenziwa kolwazi kwiiunivesithi asiyonto engathathi cala kwaye yenzeka ngeendlelangeendlela. Le thisisi iphonononga ipolitiki yolwazi ngenjongo yokucebisa nokuvelisa iindlela zokwenziwa kolwazi ezigxile ekuphazamiseni kwesiqhelo, ndlela leyo eyenziwa ngentsebenziswano nabafundi. Le Ndlela yokuphazamisa isiqhelo ivela kwindlela zokufunda nokufundisa kwinkqubo yeExtended Studies kwiUnivesithi iRhodes, apho kwiminyaka elishumi edlulileyo besisebenzisa amalinge ohlukileyo okwenza ulwazi ohlukileyo kwindlela zokufunda eziqhelekileyo. Siqulunqe inkqubo yale thisisi evumele ukuba sisebenze nolwazi ngendlela ekhokhelelisa ubuAfrika phambile, nkqubo leyo eyondla nebamba amaphupha ethu. Inkcazo-bungcali neendlela zokwenza uphando lwalo msebenzi zicacisiwe kwiphepha lokuqala lethisisi yePhD ezakupapashwa. Lo msebenzi neminye imisebenzi efana nawo isebenzisa iAfrikan Feminism ngenjongo yokubeka ngokusesikweni ndlela le ingxile kwindlela yokufundisa neengcambu zayo ezizinze eAfrika, kwaye ikhokhelisa imfundo yabantu abatsha abazifumana besenziwe amakheswa nabahlelelekileyo kunyenjwa kwasentshona kwizifundo zaseunivesithi. Abafundi ababefunda kwiES baze nezihloko, yangabo abaziphendulayo, bahlola imisebenzi yoogxa babo, kwaye bancedisa ekubhaleni amaphepha amabini abonakalisa indlela yokuphanda kusetyenziswa iziseko zokufunda zeAfrikan Feminism. Eminye imisebenzi isebenzise iziseko eziphuma kulo msebenzi wokuqala, kwaye yomibini le misebenzi iphonononga iinkcubeko zokwenza ulwazi ezikhuthaza ukuzikisa ukucinga nobuntu obunobuchule. Oku kucaciswa nzulu kumaphepha amabini. Omnye ubhalwe nomfundi kunye nombhali obefundisa kwikhosi emfutshane ebikwi-intanethi ephakathi kwamazwekazi eyenzelwe abafundi be- PhD kwiAfrican Feminist Research Methodology. Omnye umsebenzi ubhalwe ngumntu omnye, nothi wazise umsebenzi wesithathu, ikhosi yonyaka wesithathu yePolitical and International Studies yenkcazo-bungcali iAfrican Feminism. Icebo lokwenza ulwazi lisebenzisa isandla esibambe amaphupha ethu, njengesafobe esinika inkcazelo. Umnwe ngamnye umele indlela esisebenzisene ngayo kule misebenzi nakumagumbi okufundela, kunye nesikufundileyo ngokukhulisa nokukhuthaza amaphupha wabantu abasebatsha baseAfrika ngokusebenzisa imisebenzi egxile kwiinkcubeko zolwazi eziphazamisa ukwenziwa kolwazi ngendlela eqhelekileyo. Imiba emihlanu- ukwenza isakhelo, ukuqalisa, ukubona, ukudala, ukusebenzisa imifanekiso ntelekelelo- iyingqokelela yenxalenye yokwenza ulwazi ngendlela enentsebenziswano kwaye ezi ziseko zaziswa banzi kwithisisi, kwaye zicaciswe gabalala kwisishwankathelo njengengqokelela yentsebenziswano kulo msebenzi. , Thesis (PhD) -- Faculty of Education, Education, 2023
- Full Text:
- Authors: Knowles, Corinne Ruth
- Date: 2023-10-13
- Subjects: African feminism , Pedagogy , Political sociology , Knowledge, Theory of Political aspects , Transformative learning
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/402955 , vital:69909 , DOI 10.21504/10962/402955
- Description: Knowledge-making in universities is not neutral and takes different forms. This thesis critically examines the politics of knowledge to propose and present a transgressive schema for knowledge-making that is co-created with students. It emerges from teaching and learning encounters in the Humanities Extended Studies (ES) Programme at Rhodes University, where for the past decade we have experimented with different ways of knowledge-making that run counter to conventional pedagogic practices. We set up a project for the thesis that allowed us to work with knowledge in ways that are Afrocentric, and that hold and nurture our dreams. The theory and methodology of the project are explained in the first academic paper for this PhD by publication. The project and its derivatives use an African Feminist framing, and centre the ontoepistemologies of African young people who find themselves alienated and marginalised by a western bias in university curricula. Former ES student volunteers came up with topics, responded to them, reviewed each other’s work, and co-wrote two academic papers that demonstrate a praxis of African Feminist research and pedagogic principles. Two further projects practise the principles that emerge from the primary project, and together they have tested knowledge-making cultures that inspire critical thinking and creative humanity. These are explained in two further academic papers. One is co-written with the copresenter of an online inter-continental short course for PhD students on African Feminist Research Methodology. The other is single authored, and introduces the third project, a Political and International Studies third-year course on African Feminist theory. The schema for knowledge-making uses the hand, which holds our dream, as a descriptive metaphor. Each of the five fingers of the hand represents an aspect of how we have collaborated on the projects and in lecture rooms, and what this has taught us about how to nurture and inspire the dreams of young African people through transgressive knowledgemaking cultures. The five aspects – framing, activating, seeing, creating, imagining – are mutually constitutive elements of knowledge-making that are introduced throughout the thesis, and explained in careful detail in the conclusion as a synthesis of the collaborations. , Siphethe amaphupha ezandleni zethu: ukwenza iinckubeko zolwazi ezigxile ekuphazamiseni isiqhelo Isishwankathelo Ukwenziwa kolwazi kwiiunivesithi asiyonto engathathi cala kwaye yenzeka ngeendlelangeendlela. Le thisisi iphonononga ipolitiki yolwazi ngenjongo yokucebisa nokuvelisa iindlela zokwenziwa kolwazi ezigxile ekuphazamiseni kwesiqhelo, ndlela leyo eyenziwa ngentsebenziswano nabafundi. Le Ndlela yokuphazamisa isiqhelo ivela kwindlela zokufunda nokufundisa kwinkqubo yeExtended Studies kwiUnivesithi iRhodes, apho kwiminyaka elishumi edlulileyo besisebenzisa amalinge ohlukileyo okwenza ulwazi ohlukileyo kwindlela zokufunda eziqhelekileyo. Siqulunqe inkqubo yale thisisi evumele ukuba sisebenze nolwazi ngendlela ekhokhelelisa ubuAfrika phambile, nkqubo leyo eyondla nebamba amaphupha ethu. Inkcazo-bungcali neendlela zokwenza uphando lwalo msebenzi zicacisiwe kwiphepha lokuqala lethisisi yePhD ezakupapashwa. Lo msebenzi neminye imisebenzi efana nawo isebenzisa iAfrikan Feminism ngenjongo yokubeka ngokusesikweni ndlela le ingxile kwindlela yokufundisa neengcambu zayo ezizinze eAfrika, kwaye ikhokhelisa imfundo yabantu abatsha abazifumana besenziwe amakheswa nabahlelelekileyo kunyenjwa kwasentshona kwizifundo zaseunivesithi. Abafundi ababefunda kwiES baze nezihloko, yangabo abaziphendulayo, bahlola imisebenzi yoogxa babo, kwaye bancedisa ekubhaleni amaphepha amabini abonakalisa indlela yokuphanda kusetyenziswa iziseko zokufunda zeAfrikan Feminism. Eminye imisebenzi isebenzise iziseko eziphuma kulo msebenzi wokuqala, kwaye yomibini le misebenzi iphonononga iinkcubeko zokwenza ulwazi ezikhuthaza ukuzikisa ukucinga nobuntu obunobuchule. Oku kucaciswa nzulu kumaphepha amabini. Omnye ubhalwe nomfundi kunye nombhali obefundisa kwikhosi emfutshane ebikwi-intanethi ephakathi kwamazwekazi eyenzelwe abafundi be- PhD kwiAfrican Feminist Research Methodology. Omnye umsebenzi ubhalwe ngumntu omnye, nothi wazise umsebenzi wesithathu, ikhosi yonyaka wesithathu yePolitical and International Studies yenkcazo-bungcali iAfrican Feminism. Icebo lokwenza ulwazi lisebenzisa isandla esibambe amaphupha ethu, njengesafobe esinika inkcazelo. Umnwe ngamnye umele indlela esisebenzisene ngayo kule misebenzi nakumagumbi okufundela, kunye nesikufundileyo ngokukhulisa nokukhuthaza amaphupha wabantu abasebatsha baseAfrika ngokusebenzisa imisebenzi egxile kwiinkcubeko zolwazi eziphazamisa ukwenziwa kolwazi ngendlela eqhelekileyo. Imiba emihlanu- ukwenza isakhelo, ukuqalisa, ukubona, ukudala, ukusebenzisa imifanekiso ntelekelelo- iyingqokelela yenxalenye yokwenza ulwazi ngendlela enentsebenziswano kwaye ezi ziseko zaziswa banzi kwithisisi, kwaye zicaciswe gabalala kwisishwankathelo njengengqokelela yentsebenziswano kulo msebenzi. , Thesis (PhD) -- Faculty of Education, Education, 2023
- Full Text:
An in-depth investigation of an early literacy intervention in Grade R in the Eastern Cape Province, South Africa
- Authors: Hodgskiss, Jennifer Adelé
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/366222 , vital:65844
- Description: Thesis embargoed. Expected release date early 2025. , Thesis (PhD) -- Faculty of Education, Education, 2023
- Full Text:
- Authors: Hodgskiss, Jennifer Adelé
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/366222 , vital:65844
- Description: Thesis embargoed. Expected release date early 2025. , Thesis (PhD) -- Faculty of Education, Education, 2023
- Full Text:
Exploring the value of an educational partnership within a multilingual pre-school setting
- Authors: Maritz, Anneliese
- Date: 2022-10-04
- Subjects: Early childhood education Parent participation South Africa Eastern Cape , Early childhood teachers Training of , Home and school South Africa Eastern Cape , Parent-teacher relationships South Africa Eastern Cape , Communication and education South Africa Eastern Cape
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/327111 , vital:61082 , DOI 10.21504/10962/327111
- Description: This modest research project was situated in a multilingual Early Childhood Development (ECD) setting in the Eastern Cape (EC) province of South Africa. In the context of high levels of poverty and unemployment in the EC, issues such as under-funding, the nature of the training of practitioners, translating the importance of learning through play into practice, difficulties dealing with diverse cultural practices and the use of multiple languages, all impact ECD provision. Research has shown that parental involvement and creating parent-school partnerships can assist children to progress at school. The overall objectives of this project were to explore how a team in an ECD centre might communicate more effectively with parents and how early stimulation practices in home and school might benefit the child’s development. The theoretical framework draws upon Vygotsky’s (1978) socio-cultural historical theory, Bernstein’s (1971) elaborated and restricted language codes and Bourdieu’s (1977) concepts of social reproduction. A research project in the Netherlands Thuis in School, used an education partnership approach (Iliás et al., 2019). They developed a manual that was adapted for our local context by drawing from the theories mentioned, and to counter the dominant approaches where parenting programs have often been offered from a deficit, narrow perspective. Action Research guided the interventionist approach to workshop sessions, to enable mutual capacity-building of parents and practitioners. To ensure informed consent, participants’ first languages were used. High risk factors related to photographs and videos of participating parents and minor children were successfully addressed. Pre- and post-interviews and workshop data were analysed using template analysis, within a constructivist paradigm. Findings include vignettes to introduce the contexts and parents' ideas prior to the sessions. Then, sessions are summarised as action cycles, with key participants' responses. Finally, post-session evaluations highlight the topics the parents found most meaningful; and parents’ and practitioner accounts of changes in practices. This research illustrates ways that educational partnership elements can influence practice and policy, to improve home and school environments for the benefit of children. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2022
- Full Text:
- Authors: Maritz, Anneliese
- Date: 2022-10-04
- Subjects: Early childhood education Parent participation South Africa Eastern Cape , Early childhood teachers Training of , Home and school South Africa Eastern Cape , Parent-teacher relationships South Africa Eastern Cape , Communication and education South Africa Eastern Cape
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/327111 , vital:61082 , DOI 10.21504/10962/327111
- Description: This modest research project was situated in a multilingual Early Childhood Development (ECD) setting in the Eastern Cape (EC) province of South Africa. In the context of high levels of poverty and unemployment in the EC, issues such as under-funding, the nature of the training of practitioners, translating the importance of learning through play into practice, difficulties dealing with diverse cultural practices and the use of multiple languages, all impact ECD provision. Research has shown that parental involvement and creating parent-school partnerships can assist children to progress at school. The overall objectives of this project were to explore how a team in an ECD centre might communicate more effectively with parents and how early stimulation practices in home and school might benefit the child’s development. The theoretical framework draws upon Vygotsky’s (1978) socio-cultural historical theory, Bernstein’s (1971) elaborated and restricted language codes and Bourdieu’s (1977) concepts of social reproduction. A research project in the Netherlands Thuis in School, used an education partnership approach (Iliás et al., 2019). They developed a manual that was adapted for our local context by drawing from the theories mentioned, and to counter the dominant approaches where parenting programs have often been offered from a deficit, narrow perspective. Action Research guided the interventionist approach to workshop sessions, to enable mutual capacity-building of parents and practitioners. To ensure informed consent, participants’ first languages were used. High risk factors related to photographs and videos of participating parents and minor children were successfully addressed. Pre- and post-interviews and workshop data were analysed using template analysis, within a constructivist paradigm. Findings include vignettes to introduce the contexts and parents' ideas prior to the sessions. Then, sessions are summarised as action cycles, with key participants' responses. Finally, post-session evaluations highlight the topics the parents found most meaningful; and parents’ and practitioner accounts of changes in practices. This research illustrates ways that educational partnership elements can influence practice and policy, to improve home and school environments for the benefit of children. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2022
- Full Text:
Views of the journey of grade 1 learners with barriers to learning, in the inclusive education system: a multi-level systemic investigation
- Van Vuuren, Cornelia Margaretha
- Authors: Van Vuuren, Cornelia Margaretha
- Date: 2022-10-04
- Subjects: Inclusive education South Africa Eastern Cape , Special education teachers South Africa Eastern Cape Attitudes , South Africa. Department of Education , Children with disabilities Education (Elementary) Government policy South Africa , Special education teachers Training of South Africa Eastern Cape
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/327122 , vital:61083 , DOI 10.21504/10962/327122
- Description: Embedded in South Africa’s humanitarian discourse, inclusive education (IE) followed global trends of inclusion of all people into wider society without discrimination. Inclusion in mainstream schools should also, according to the Salamanca agreement provide equal quality education, enabling learners with special educational needs (LSEN) to reach their full potential as a basic human right. IE started in South Africa with the implementation of the inclusive policy EWP6 in 2001. Including all children with barriers to learning in schools in their communities promoted social inclusion with their peers. The DoE introduced the Policy of Screening, Identification, Assessment and Support (SIAS) in 2014. This policy was implemented to assist teachers to identify learning barriers, as a means of offering support to these learners through the inclusive system. However, it seems that educators found this process cumbersome, without resources to maintain the process and with multiple systemic barriers preventing, rather than enhancing, support to LSEN. This multi-level systemic study explores the views of educators and other stakeholders on the effectiveness of the IE system in supporting LSEN, to serve the best interests of these learners in their first year of formal schooling. The study was conducted in three selected diverse mainstream Eastern Cape (EC) rural schools, involving the views of educators, district officials and parents. The study probed the impact of the inclusive system on LSEN’s development and social wellbeing, the perceived effects and benefits of the current system, and how the education model contributes towards human rights objectives and constitutional imperatives. The study acknowledges the theories and policies of the current inclusive system as promoting inclusion, but not being successfully realised in rural areas in the South African context, due to several systemic and contextual barriers. The findings revealed that although all participants noted the possible benefits of IE, the current system did not serve the individual educational needs of LSEN in rural mainstream schools, in their first formal year of schooling. Several constraints were reported including lack of resources, insufficient Allied Health support services, and insufficient training of educators. These lead to feelings of inadequacy in educators, along with systemic and contextual barriers and financial constraints in the schools. There also seems to be a need for better collaboration between education and other departments serving children and communities. To conclude, this study suggests a broader multi-level networked system, in which there needs to be greater interaction between the DoE and other government departments supporting children with barriers, like the Departments of Health (DoH), Social Development (DSD) and Justice (DoJ). , Thesis (PhD) -- Faculty of Humanities, Psychology, 2022
- Full Text:
- Authors: Van Vuuren, Cornelia Margaretha
- Date: 2022-10-04
- Subjects: Inclusive education South Africa Eastern Cape , Special education teachers South Africa Eastern Cape Attitudes , South Africa. Department of Education , Children with disabilities Education (Elementary) Government policy South Africa , Special education teachers Training of South Africa Eastern Cape
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/327122 , vital:61083 , DOI 10.21504/10962/327122
- Description: Embedded in South Africa’s humanitarian discourse, inclusive education (IE) followed global trends of inclusion of all people into wider society without discrimination. Inclusion in mainstream schools should also, according to the Salamanca agreement provide equal quality education, enabling learners with special educational needs (LSEN) to reach their full potential as a basic human right. IE started in South Africa with the implementation of the inclusive policy EWP6 in 2001. Including all children with barriers to learning in schools in their communities promoted social inclusion with their peers. The DoE introduced the Policy of Screening, Identification, Assessment and Support (SIAS) in 2014. This policy was implemented to assist teachers to identify learning barriers, as a means of offering support to these learners through the inclusive system. However, it seems that educators found this process cumbersome, without resources to maintain the process and with multiple systemic barriers preventing, rather than enhancing, support to LSEN. This multi-level systemic study explores the views of educators and other stakeholders on the effectiveness of the IE system in supporting LSEN, to serve the best interests of these learners in their first year of formal schooling. The study was conducted in three selected diverse mainstream Eastern Cape (EC) rural schools, involving the views of educators, district officials and parents. The study probed the impact of the inclusive system on LSEN’s development and social wellbeing, the perceived effects and benefits of the current system, and how the education model contributes towards human rights objectives and constitutional imperatives. The study acknowledges the theories and policies of the current inclusive system as promoting inclusion, but not being successfully realised in rural areas in the South African context, due to several systemic and contextual barriers. The findings revealed that although all participants noted the possible benefits of IE, the current system did not serve the individual educational needs of LSEN in rural mainstream schools, in their first formal year of schooling. Several constraints were reported including lack of resources, insufficient Allied Health support services, and insufficient training of educators. These lead to feelings of inadequacy in educators, along with systemic and contextual barriers and financial constraints in the schools. There also seems to be a need for better collaboration between education and other departments serving children and communities. To conclude, this study suggests a broader multi-level networked system, in which there needs to be greater interaction between the DoE and other government departments supporting children with barriers, like the Departments of Health (DoH), Social Development (DSD) and Justice (DoJ). , Thesis (PhD) -- Faculty of Humanities, Psychology, 2022
- Full Text:
Effect of Helicosporidium sp. (Chlorophyta; Trebouxiophyceae) infection on Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae), a biological control agent for the invasive Salvinia molesta D.S. Mitchell (Salviniaceae) in South
- Authors: Mphephu, Tshililo Emmanuel
- Date: 2022-10-14
- Subjects: Salvinia molesta South Africa , Weeds Biological control , Cyrtobagous salviniae , Ketoconazole
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365815 , vital:65792 , DOI https://doi.org/10.21504/10962/365815
- Description: The effectiveness of established biological control agents depends on biotic and abiotic interactions in the introduced range. The weevil, Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae), was released as a biological control against Salvinia molesta D.S. Mitchell (Salviniaceae) in South Africa in 1985. This agent has been highly successful against S. molesta and has significantly reduced the weed’s populations around the country. However, in 2007, the parasitic alga, Helicosporidium sp. (an undescribed species), was detected in field-collected C. salviniae adults in South Africa. The distribution and impacts of this disease on the weevil and its efficacy as a control agent were not known. In this thesis, the prevalence, infection load, and impact of Helicosporidium sp. on C. salviniae was determined. In 2019, adult weevils were collected from 10 sites across the Eastern Cape, KwaZulu-Natal, Limpopo, and Western Cape provinces and screened to determine the occurrence, infection load, and geographic distribution of Helicosporidium sp. Transmission mechanisms of this disease in C. salviniae were then evaluated. The possible impact of Helicosporidium sp. was assessed by comparing the feeding rates and the reproductive output of the diseased and healthy adults of C. salviniae. An attempt was then made to eliminate the disease in C. salviniae through the application of the antibiotic, ketoconazole. Further, the role of temperature on infection load in C. salviniae was also assessed. Finally, recommendations for the long-term biological control programme against S. molesta in South Africa were made. The disease covers the entire distribution range of C. salviniae in South Africa, with the disease occurrence rate ranging from 92.15% to 100% insects infected per site. Helicosporidium sp. was found to transmit vertically within the populations of C. salviniae. Infection by the Helicosporidium sp. disease reduced the reproductive output of C. salviniae as well its impact on biomass reduction of S. molesta when a diseased culture was compared to a healthy culture from the USA. 98.44 to 98.55% of Helicosporidium sp. loads were reduced through multiple applications of ketoconazole concentrations under in vitro trials. In vivo treatments resulted in 70% control of Helicosporidium sp. in the adults of C. salviniae that were fed ketoconazole three times over a 21 day period. Adult C. salviniae feeding and survival performances were similar when fed fronds of S. molesta inoculated with ketoconazole and water. The lowest and highest disease loads of Helicosporidium sp. were recorded when the weevils were reared at 30°C and 14°C, respectively. As expected, the highest impact and reproductive output of C. salviniae were at 30°C. The evaluations discussed in this thesis highlight the role of diseases in biological control agents, and gaps in both the pre-release and post-release monitoring that should integrate screening of diseases in these studies. Although the combined application of the antibiotic and temperature will reduce Helicosporidium sp. loads and impact, this technology is most likely only applicable where the weevils are reared in small numbers in a rearing facility and not really applicable to the field situation. It is important to release healthy agents that will cause efficient control of the target weed plant species, therefore, when introducing new biological control agents, the health status of such agents needs to be understood. Therefore, long-term field monitoring and assessment of the impact of C. salviniae on S. molesta should be conducted to track all the changes that may result due to the presence of Helicosporidium sp. This long-term monitoring and assessment will give a more informative role of Helicosporidium sp. in field populations of C. salviniae. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2022
- Full Text:
- Authors: Mphephu, Tshililo Emmanuel
- Date: 2022-10-14
- Subjects: Salvinia molesta South Africa , Weeds Biological control , Cyrtobagous salviniae , Ketoconazole
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365815 , vital:65792 , DOI https://doi.org/10.21504/10962/365815
- Description: The effectiveness of established biological control agents depends on biotic and abiotic interactions in the introduced range. The weevil, Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae), was released as a biological control against Salvinia molesta D.S. Mitchell (Salviniaceae) in South Africa in 1985. This agent has been highly successful against S. molesta and has significantly reduced the weed’s populations around the country. However, in 2007, the parasitic alga, Helicosporidium sp. (an undescribed species), was detected in field-collected C. salviniae adults in South Africa. The distribution and impacts of this disease on the weevil and its efficacy as a control agent were not known. In this thesis, the prevalence, infection load, and impact of Helicosporidium sp. on C. salviniae was determined. In 2019, adult weevils were collected from 10 sites across the Eastern Cape, KwaZulu-Natal, Limpopo, and Western Cape provinces and screened to determine the occurrence, infection load, and geographic distribution of Helicosporidium sp. Transmission mechanisms of this disease in C. salviniae were then evaluated. The possible impact of Helicosporidium sp. was assessed by comparing the feeding rates and the reproductive output of the diseased and healthy adults of C. salviniae. An attempt was then made to eliminate the disease in C. salviniae through the application of the antibiotic, ketoconazole. Further, the role of temperature on infection load in C. salviniae was also assessed. Finally, recommendations for the long-term biological control programme against S. molesta in South Africa were made. The disease covers the entire distribution range of C. salviniae in South Africa, with the disease occurrence rate ranging from 92.15% to 100% insects infected per site. Helicosporidium sp. was found to transmit vertically within the populations of C. salviniae. Infection by the Helicosporidium sp. disease reduced the reproductive output of C. salviniae as well its impact on biomass reduction of S. molesta when a diseased culture was compared to a healthy culture from the USA. 98.44 to 98.55% of Helicosporidium sp. loads were reduced through multiple applications of ketoconazole concentrations under in vitro trials. In vivo treatments resulted in 70% control of Helicosporidium sp. in the adults of C. salviniae that were fed ketoconazole three times over a 21 day period. Adult C. salviniae feeding and survival performances were similar when fed fronds of S. molesta inoculated with ketoconazole and water. The lowest and highest disease loads of Helicosporidium sp. were recorded when the weevils were reared at 30°C and 14°C, respectively. As expected, the highest impact and reproductive output of C. salviniae were at 30°C. The evaluations discussed in this thesis highlight the role of diseases in biological control agents, and gaps in both the pre-release and post-release monitoring that should integrate screening of diseases in these studies. Although the combined application of the antibiotic and temperature will reduce Helicosporidium sp. loads and impact, this technology is most likely only applicable where the weevils are reared in small numbers in a rearing facility and not really applicable to the field situation. It is important to release healthy agents that will cause efficient control of the target weed plant species, therefore, when introducing new biological control agents, the health status of such agents needs to be understood. Therefore, long-term field monitoring and assessment of the impact of C. salviniae on S. molesta should be conducted to track all the changes that may result due to the presence of Helicosporidium sp. This long-term monitoring and assessment will give a more informative role of Helicosporidium sp. in field populations of C. salviniae. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2022
- Full Text:
Synthesis, characterization and host-guest complexes of supramolecular assemblies based on calixarenes and cucurbiturils
- Authors: Baa, Ebenezer
- Date: 2022-10-14
- Subjects: Supramolecular chemistry , Calixarenes , Cucurbiturils , Metal-organic frameworks , Macrocyclic compounds , Drug delivery systems
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365621 , vital:65765 , DOI https://doi.org/10.21504/10962/365621
- Description: The field of supramolecular chemistry has grown large and wide in both deepness of understanding, range of topics covered and scope and applications. Supramolecular self-assemblies are facilitated by a wide range of non-covalent intra and inter molecular interactions that range from hydrogen bonding to π-interaction and van der Waals. Macrocyclic compounds such as cucurbiturils and calixarenes have emerged as important classes of compounds with excellent potential of forming supramolecular assemblies. The porous nature of these compounds enables them to form host-guest supramolecular complexes stabilized by diverse range of non-covalent interactions. Furthermore, these compounds contain donor atoms capable of forming bonds with metal ions to yield metal complexes with interesting porous characteristics that deviate from their traditional hydrophobic cavity. The versatile nature of the resulting pores imply that they can accommodate diverse types of guests. This work explores the synthesis and characterization of a host of calixarenes and cucurbiturils. Self-assembly of these macrocycles with various metal ions results to the formation of porous metal organic framework (MOF) complexes. Four new calixarene typed compounds obtained from aromatic aldehydes and twenty-six cucurbituril metal complexes are reported. These macrocylces and their metal complexes also form supramolecular complexes with DMSO, methanol, isoniazid hydrochloride and ciprofloxacin hydrochlorides through either self-assembly, mechanochemistry and exposure to solvent vapors. The bulk materials have been characterized using nuclear magnetic resonance spectroscopy (NMR), Fourier transformed infrared spectroscopy (FTIR), powder and single crystal diffraction techniques and thermal studies thermogravimetric analysis (TGA) and differential thermal calorimetry (DSC). Data obtained from this study reveals that calixarenes can form supramolecular complexes with a frequently used laboratory solvents with BN22 showing appreciable selectivity for DMSO sorption from a solvent mixture. These compounds also form supramolecular complexes with drug molecules such as isoniazid and ciprofloxacin. Furthermore, the data reveals that choice of synthetic route of supramolecular ensembles dictates if the guest drug molecule will occupy the intrinsic or extrinsic pores of cucurbituril complexes. Biological studies on the obtained complexes reveal that the cucurbituril complexes are non-cytotoxic while the calixarenes show antibacterial activity against Escherichia coli and Staphylococcus aureus. Additionally, the study showed that ciprofloxacin can be successfully released from a calixarene host in a simulated body fluid although the host was also found to cross the dialysis membrane. The results of this study are important in that; - they can be exploited and developed in the selective sorption of certain guests and - that they can be used in the development of drug delivery systems that play a dual role of delivery and therapeutic activity. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
- Full Text:
- Authors: Baa, Ebenezer
- Date: 2022-10-14
- Subjects: Supramolecular chemistry , Calixarenes , Cucurbiturils , Metal-organic frameworks , Macrocyclic compounds , Drug delivery systems
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365621 , vital:65765 , DOI https://doi.org/10.21504/10962/365621
- Description: The field of supramolecular chemistry has grown large and wide in both deepness of understanding, range of topics covered and scope and applications. Supramolecular self-assemblies are facilitated by a wide range of non-covalent intra and inter molecular interactions that range from hydrogen bonding to π-interaction and van der Waals. Macrocyclic compounds such as cucurbiturils and calixarenes have emerged as important classes of compounds with excellent potential of forming supramolecular assemblies. The porous nature of these compounds enables them to form host-guest supramolecular complexes stabilized by diverse range of non-covalent interactions. Furthermore, these compounds contain donor atoms capable of forming bonds with metal ions to yield metal complexes with interesting porous characteristics that deviate from their traditional hydrophobic cavity. The versatile nature of the resulting pores imply that they can accommodate diverse types of guests. This work explores the synthesis and characterization of a host of calixarenes and cucurbiturils. Self-assembly of these macrocycles with various metal ions results to the formation of porous metal organic framework (MOF) complexes. Four new calixarene typed compounds obtained from aromatic aldehydes and twenty-six cucurbituril metal complexes are reported. These macrocylces and their metal complexes also form supramolecular complexes with DMSO, methanol, isoniazid hydrochloride and ciprofloxacin hydrochlorides through either self-assembly, mechanochemistry and exposure to solvent vapors. The bulk materials have been characterized using nuclear magnetic resonance spectroscopy (NMR), Fourier transformed infrared spectroscopy (FTIR), powder and single crystal diffraction techniques and thermal studies thermogravimetric analysis (TGA) and differential thermal calorimetry (DSC). Data obtained from this study reveals that calixarenes can form supramolecular complexes with a frequently used laboratory solvents with BN22 showing appreciable selectivity for DMSO sorption from a solvent mixture. These compounds also form supramolecular complexes with drug molecules such as isoniazid and ciprofloxacin. Furthermore, the data reveals that choice of synthetic route of supramolecular ensembles dictates if the guest drug molecule will occupy the intrinsic or extrinsic pores of cucurbituril complexes. Biological studies on the obtained complexes reveal that the cucurbituril complexes are non-cytotoxic while the calixarenes show antibacterial activity against Escherichia coli and Staphylococcus aureus. Additionally, the study showed that ciprofloxacin can be successfully released from a calixarene host in a simulated body fluid although the host was also found to cross the dialysis membrane. The results of this study are important in that; - they can be exploited and developed in the selective sorption of certain guests and - that they can be used in the development of drug delivery systems that play a dual role of delivery and therapeutic activity. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
- Full Text:
Land use decision-making on residential plots in Fingo Village, Makhanda (Grahamstown), South Africa
- Authors: Memela, Sinenhlanhla
- Date: 2021-04-28
- Subjects: Land use South Africa Makhanda Decision making , Land use, Urban South Africa Makhanda Decision making , Residential real estate South Africa Makhanda , Urban ecology (Sociology) South Africa Makhanda , Urban gardening South Africa Makhanda , Urban livestock production systems South Africa Makhanda
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/322694 , vital:60589 , DOI 10.21504/10962/322694
- Description: This study seeks to understand land use decision-making dynamics on large residential plots in Fingo Village, Makhanda (Grahamstown). Fingo Village was selected as a study area because it is one of the poorest urban settings in South Africa where urban poverty is observed alongside access to land. A dominant economic perspective not only suggests that land use decisions are motivated by economic motives, but also implies that access to land would enable people to generate income from its use to improve their livelihoods. This study argues against an uncritical embrace of this assumption. Lefebvre’s production of space thesis provides a holistic understanding of the factors involved in the making of land use decisions. The focus of this study is on the dialectic process in the spatial triad– spatial practice, representational space and representations of space. This involved the reading of government policies and legislation together with local lived experiences to gain an understanding of the particular spatial practices seen in Fingo Village. Snowball and convenience sampling were used to select 36 household plots in Fingo Village. Primary data was gathered by means of semi-structured interviews and participatory mapping while additional information was sourced from secondary sources and desktop analysis. The findings of the study show that there is no uniform pattern of land use and success. Different land use activities found on the selected residential plots, including the main house, backyard flat or flats, spaza shops, a funeral parlour, livestock keeping, cultural use (a kraal for ancestral worship) and food gardening. These activities are motivated by residents’ perceptions and attitudes towards their spaces, as well as the value and meaning they attach to the land which is not limited to economic factors, but is also influenced by socio-cultural, political and biophysical considerations. Although some spatial practices are prohibited by the government, they are important to the residents. Other participants fail to use the land as would be expected by a conventional economic perspective, due to spatial conflict relating to different interests as a result of collective land ownership and the failure of municipalities to enforce policies and regulations. The fact that numerous factors influence households’ land use decisions means that access to land does not always directly translate into economic benefits. It is all about what people think or do about their land, as well as what the state lays out in terms of policy and legislation, that will influence whether those people with large plots of land will ‘prosper’ or not. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
Land use decision-making on residential plots in Fingo Village, Makhanda (Grahamstown), South Africa
- Authors: Memela, Sinenhlanhla
- Date: 2021-04-28
- Subjects: Land use South Africa Makhanda Decision making , Land use, Urban South Africa Makhanda Decision making , Residential real estate South Africa Makhanda , Urban ecology (Sociology) South Africa Makhanda , Urban gardening South Africa Makhanda , Urban livestock production systems South Africa Makhanda
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/322694 , vital:60589 , DOI 10.21504/10962/322694
- Description: This study seeks to understand land use decision-making dynamics on large residential plots in Fingo Village, Makhanda (Grahamstown). Fingo Village was selected as a study area because it is one of the poorest urban settings in South Africa where urban poverty is observed alongside access to land. A dominant economic perspective not only suggests that land use decisions are motivated by economic motives, but also implies that access to land would enable people to generate income from its use to improve their livelihoods. This study argues against an uncritical embrace of this assumption. Lefebvre’s production of space thesis provides a holistic understanding of the factors involved in the making of land use decisions. The focus of this study is on the dialectic process in the spatial triad– spatial practice, representational space and representations of space. This involved the reading of government policies and legislation together with local lived experiences to gain an understanding of the particular spatial practices seen in Fingo Village. Snowball and convenience sampling were used to select 36 household plots in Fingo Village. Primary data was gathered by means of semi-structured interviews and participatory mapping while additional information was sourced from secondary sources and desktop analysis. The findings of the study show that there is no uniform pattern of land use and success. Different land use activities found on the selected residential plots, including the main house, backyard flat or flats, spaza shops, a funeral parlour, livestock keeping, cultural use (a kraal for ancestral worship) and food gardening. These activities are motivated by residents’ perceptions and attitudes towards their spaces, as well as the value and meaning they attach to the land which is not limited to economic factors, but is also influenced by socio-cultural, political and biophysical considerations. Although some spatial practices are prohibited by the government, they are important to the residents. Other participants fail to use the land as would be expected by a conventional economic perspective, due to spatial conflict relating to different interests as a result of collective land ownership and the failure of municipalities to enforce policies and regulations. The fact that numerous factors influence households’ land use decisions means that access to land does not always directly translate into economic benefits. It is all about what people think or do about their land, as well as what the state lays out in terms of policy and legislation, that will influence whether those people with large plots of land will ‘prosper’ or not. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
An examination of activism and ‘political listening’ during the year of student protest at the University of Cape Town from 9 March 2015 to 9 March 2016
- Mufamadi, Azwihangwisi Eugene
- Authors: Mufamadi, Azwihangwisi Eugene
- Date: 2022-10-04
- Subjects: Student movements South Africa Cape Town , Democracy South Africa , Listening Political aspects , Journalistic ethics , Journalism Political aspects , Communication in social action South Africa Cape Town , University of Cape Town , Cape Times Ltd.
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/327144 , vital:61085 , DOI 10.21504/10962/327144
- Description: This study sets out to examine democratic participation in South Africa and the role that ‘political listening’ could play in making participation more equitable. It considers protest action on a South African university campus, which at times not only resulted in significant and swift concessions from the university leadership but also sparked national political action which got an equally swift response from the South African government. It considers the social movement, the RhodesMustFall movement (RMF), as one way in which students can organise themselves to get a better hearing from the University of Cape Town (UCT) management in their attempt to make a meaningful contribution to the university’s micro democracy. This study examines whether the interaction between the UCT management and RMF could be considered ‘political listening’, and the possible role of the Cape Times newspaper within this context of participation. Using data gathered through interviews, written communications, observation and newspaper articles, the study shows that in all of the interactions between RMF and the UCT management, both groups were seldom willing to forego their power to engage in genuine listening. Instead, the two parties guessed at what power the other party might have and acted to reduce that power. It is in this context of guessing at and figuring what power the other party has that listening occurs. Furthermore, the study shows that during the RMF protest, the UCT management viewed their responsibility for the institution mainly through the lens of Private Property Law which framed protest as something to be dealt with by restoring law and order. The study also details the role of the Cape Times newspaper in the interactions between RMF and the UCT management and considers if this role could be political listening. The study is exploratory and demonstrates how political listening could work more optimally in real-life instances. , Thesis (PhD) -- Faculty of Humanities, Journalism and Media Studies, 2022
- Full Text:
- Authors: Mufamadi, Azwihangwisi Eugene
- Date: 2022-10-04
- Subjects: Student movements South Africa Cape Town , Democracy South Africa , Listening Political aspects , Journalistic ethics , Journalism Political aspects , Communication in social action South Africa Cape Town , University of Cape Town , Cape Times Ltd.
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/327144 , vital:61085 , DOI 10.21504/10962/327144
- Description: This study sets out to examine democratic participation in South Africa and the role that ‘political listening’ could play in making participation more equitable. It considers protest action on a South African university campus, which at times not only resulted in significant and swift concessions from the university leadership but also sparked national political action which got an equally swift response from the South African government. It considers the social movement, the RhodesMustFall movement (RMF), as one way in which students can organise themselves to get a better hearing from the University of Cape Town (UCT) management in their attempt to make a meaningful contribution to the university’s micro democracy. This study examines whether the interaction between the UCT management and RMF could be considered ‘political listening’, and the possible role of the Cape Times newspaper within this context of participation. Using data gathered through interviews, written communications, observation and newspaper articles, the study shows that in all of the interactions between RMF and the UCT management, both groups were seldom willing to forego their power to engage in genuine listening. Instead, the two parties guessed at what power the other party might have and acted to reduce that power. It is in this context of guessing at and figuring what power the other party has that listening occurs. Furthermore, the study shows that during the RMF protest, the UCT management viewed their responsibility for the institution mainly through the lens of Private Property Law which framed protest as something to be dealt with by restoring law and order. The study also details the role of the Cape Times newspaper in the interactions between RMF and the UCT management and considers if this role could be political listening. The study is exploratory and demonstrates how political listening could work more optimally in real-life instances. , Thesis (PhD) -- Faculty of Humanities, Journalism and Media Studies, 2022
- Full Text:
Functional biogeography: evaluating community assemblage patterns and ecosystem functioning in intertidal systems using trait-based approaches
- Authors: Gusha, Molline Natanah C
- Date: 2022-10-14
- Subjects: Biogeography , Marine algae , Benthic ecology , Invertebrates , Functional redundancy , Ocean temperature , Biology Classification
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365792 , vital:65790 , DOI https://doi.org/10.21504/10962/365792
- Description: Analyses of taxonomic diversity patterns within coastal systems has been critical in the development of the theory of biogeography. Increasing evidence, however, shows that the variety of functions that species perform in ecosystems (rather than their taxonomic identity) is a better predictor of the influence of the environment on the species. This information has been useful in predictive ecology leading to the development of trait-based approaches (TBA). Until the late 1970s, however, limited effort (particularly in marine systems) was channeled towards patterns in functional species traits and how they may be affected by changes in environmental gradients. Here, I mapped the functional biogeography of the South African coastline based on a suite of species' reproduction and development traits. Because species composition is one of the key tools used by zoogeographers to map species distribution patterns, I expected lower variability in trait composition within main biogeographic regions than in intervening transition zones based on the habitat templet theory and following the biomass ratio and limiting similarity hypotheses. In brief, the habitat templet theory proposes that “the habitat provides a templet upon which evolution forges species characteristics”, while the biomass ratio hypothesis assumes that the most abundant species traits determine ecosystem functioning. The limiting similarity hypothesis also sometimes referred to as the niche complementarity hypothesis, however, predicts that species can coexist if their niches complement one another. In light of the habitat being an evolutionary templet, abiotic and biotic habitat patterns were measured as nearshore SST and chlorophyll-a gradients, respectively. I expected the SST gradient to act as the stronger key filter of trait diversification because temperature is often considered the most influential environmental factor affecting species survival with seasonality of SST affecting the timing of spawning and along with food availability, possibly influencing fecundity. Functional trait data were thus compiled for macroinvertebrate species collected from fifty-two rocky shore sites from three main bioregions (east, south, and west) and two transition zones (south-west and south-east). Biological trait analysis and functional diversity indices were used to evaluate how traits related to species development and reproduction respond to temperature and chlorophyll -a (used as a proxy for food availability) gradients along the coastline. GLMM and hierarchical cluster analyses showed distinct patterns/shifts in SST and chlorophyll-a gradients across bioregions, with two main breaks in SST separating the east and south-east overlap (SEO) bioregions from the south, south-west overlap (SWO) and west bioregions. In contrast, chlorophyll-a exhibited three major breaks with the east, SEO–south–SWO, and west clustering independently of each other. The RLQ analysis (a type of co-inertia analysis) which simultaneously ordinates 3-matrix datasets [i.e., (environment × site[R]), (species × site[L]) and (species × traits [Q])] showed that the higher SST gradient on the east and SEO promoted higher abundance and biomass of simultaneous hermaphrodites while higher chlorophyll-a gradients on the SWO and west coasts strongly promoted reproductive maturity at larger-sizes. The combined fourth-corner analyses showed that the modalities within the development trait domain responding to chlorophyll-a gradients primarily included filter feeders, sessile and swimming species and also species living on the infratidal zone. In addition, the reproduction trait domain showed higher sensitivity and association to differences in chlorophyll-a and SST gradients than development traits. Overall, SST and chlorophyll-a gradients influenced the distribution of the most dominant traits as indicated by shifts in community-weighted mean trait values across bioregions. This suggests the importance of habitat filtering on coastal species reproduction. A separate study evaluating the influence of large-scale biogeographic effects vs the micro-scale biogenic habitat structure offered by coralline seaweeds across 24 sites revealed some notable effects of both factors on the diversity and abundance of macroalgal epifauna. There was a notable biogeographic influence on epifauna, with the SEO recording the highest epifaunal species richness and abundance, followed by the south coast, then the SWO and lastly the west coast. In addition, the total biomass gradient of the corallines followed a similar trend. The epifauna however, showed no host-specificity, illustrating that epifauna may not be species–centric as commonly assumed, and the higher diversity of epifaunal diversity may well be simply because those corallines are the available habitat within the sampled part of the coastline. Lastly, macroinvertebrate trait distribution on the South African coastline confirms that the habitat, particularly the biotic filter (in this case chl-a) provides a templet upon which evolution forges species traits. However, since temperature is a proxy for nutrient availability (cold upwelling brings nutrients), then temperature drives chlorophyll-a. Subsequently this means the abiotic component indirectly drives trait distribution by influencing the biotic environment (chl-a). For epifauna species, also, the coralline diversity and composition can also be regarded as a biotic filter influencing the epifaunal abundances and composition across different bioregions. Moreover, since temperature is regarded as a conservative trait in seaweeds, temperature tolerance defines the biogeographical boundaries of seaweeds, therefore temperature may be indirectly affecting epifauna abundances through coralline species diversity and biomass. In summary, considering the deterministic processes governing ecosystem functioning and community assemblage, the mass ratio and limiting similarity hypotheses showed complementary effects. Different bioregions provided variable support for these two hypotheses, but overall, the mass ratio hypothesis (weighted by species biomass) received stronger support and may be more meaningful to the interpretation of ecosystem functioning and persistence within rocky shore systems. Lastly, although, the SWO showed some of the characteristics of a subtraction zone based on the relatively low abundance, diversity, and biomass measures. Nonetheless, there was evidence of high functional redundancy across all other four bioregions. This suggests that in the context of development and reproduction traits, the rocky shore ecosystem along the SA coastline may be functionally stable at this stage. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2022
- Full Text:
- Authors: Gusha, Molline Natanah C
- Date: 2022-10-14
- Subjects: Biogeography , Marine algae , Benthic ecology , Invertebrates , Functional redundancy , Ocean temperature , Biology Classification
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365792 , vital:65790 , DOI https://doi.org/10.21504/10962/365792
- Description: Analyses of taxonomic diversity patterns within coastal systems has been critical in the development of the theory of biogeography. Increasing evidence, however, shows that the variety of functions that species perform in ecosystems (rather than their taxonomic identity) is a better predictor of the influence of the environment on the species. This information has been useful in predictive ecology leading to the development of trait-based approaches (TBA). Until the late 1970s, however, limited effort (particularly in marine systems) was channeled towards patterns in functional species traits and how they may be affected by changes in environmental gradients. Here, I mapped the functional biogeography of the South African coastline based on a suite of species' reproduction and development traits. Because species composition is one of the key tools used by zoogeographers to map species distribution patterns, I expected lower variability in trait composition within main biogeographic regions than in intervening transition zones based on the habitat templet theory and following the biomass ratio and limiting similarity hypotheses. In brief, the habitat templet theory proposes that “the habitat provides a templet upon which evolution forges species characteristics”, while the biomass ratio hypothesis assumes that the most abundant species traits determine ecosystem functioning. The limiting similarity hypothesis also sometimes referred to as the niche complementarity hypothesis, however, predicts that species can coexist if their niches complement one another. In light of the habitat being an evolutionary templet, abiotic and biotic habitat patterns were measured as nearshore SST and chlorophyll-a gradients, respectively. I expected the SST gradient to act as the stronger key filter of trait diversification because temperature is often considered the most influential environmental factor affecting species survival with seasonality of SST affecting the timing of spawning and along with food availability, possibly influencing fecundity. Functional trait data were thus compiled for macroinvertebrate species collected from fifty-two rocky shore sites from three main bioregions (east, south, and west) and two transition zones (south-west and south-east). Biological trait analysis and functional diversity indices were used to evaluate how traits related to species development and reproduction respond to temperature and chlorophyll -a (used as a proxy for food availability) gradients along the coastline. GLMM and hierarchical cluster analyses showed distinct patterns/shifts in SST and chlorophyll-a gradients across bioregions, with two main breaks in SST separating the east and south-east overlap (SEO) bioregions from the south, south-west overlap (SWO) and west bioregions. In contrast, chlorophyll-a exhibited three major breaks with the east, SEO–south–SWO, and west clustering independently of each other. The RLQ analysis (a type of co-inertia analysis) which simultaneously ordinates 3-matrix datasets [i.e., (environment × site[R]), (species × site[L]) and (species × traits [Q])] showed that the higher SST gradient on the east and SEO promoted higher abundance and biomass of simultaneous hermaphrodites while higher chlorophyll-a gradients on the SWO and west coasts strongly promoted reproductive maturity at larger-sizes. The combined fourth-corner analyses showed that the modalities within the development trait domain responding to chlorophyll-a gradients primarily included filter feeders, sessile and swimming species and also species living on the infratidal zone. In addition, the reproduction trait domain showed higher sensitivity and association to differences in chlorophyll-a and SST gradients than development traits. Overall, SST and chlorophyll-a gradients influenced the distribution of the most dominant traits as indicated by shifts in community-weighted mean trait values across bioregions. This suggests the importance of habitat filtering on coastal species reproduction. A separate study evaluating the influence of large-scale biogeographic effects vs the micro-scale biogenic habitat structure offered by coralline seaweeds across 24 sites revealed some notable effects of both factors on the diversity and abundance of macroalgal epifauna. There was a notable biogeographic influence on epifauna, with the SEO recording the highest epifaunal species richness and abundance, followed by the south coast, then the SWO and lastly the west coast. In addition, the total biomass gradient of the corallines followed a similar trend. The epifauna however, showed no host-specificity, illustrating that epifauna may not be species–centric as commonly assumed, and the higher diversity of epifaunal diversity may well be simply because those corallines are the available habitat within the sampled part of the coastline. Lastly, macroinvertebrate trait distribution on the South African coastline confirms that the habitat, particularly the biotic filter (in this case chl-a) provides a templet upon which evolution forges species traits. However, since temperature is a proxy for nutrient availability (cold upwelling brings nutrients), then temperature drives chlorophyll-a. Subsequently this means the abiotic component indirectly drives trait distribution by influencing the biotic environment (chl-a). For epifauna species, also, the coralline diversity and composition can also be regarded as a biotic filter influencing the epifaunal abundances and composition across different bioregions. Moreover, since temperature is regarded as a conservative trait in seaweeds, temperature tolerance defines the biogeographical boundaries of seaweeds, therefore temperature may be indirectly affecting epifauna abundances through coralline species diversity and biomass. In summary, considering the deterministic processes governing ecosystem functioning and community assemblage, the mass ratio and limiting similarity hypotheses showed complementary effects. Different bioregions provided variable support for these two hypotheses, but overall, the mass ratio hypothesis (weighted by species biomass) received stronger support and may be more meaningful to the interpretation of ecosystem functioning and persistence within rocky shore systems. Lastly, although, the SWO showed some of the characteristics of a subtraction zone based on the relatively low abundance, diversity, and biomass measures. Nonetheless, there was evidence of high functional redundancy across all other four bioregions. This suggests that in the context of development and reproduction traits, the rocky shore ecosystem along the SA coastline may be functionally stable at this stage. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2022
- Full Text:
Dynamics of charge movement in ∞-Al2O3:C,Mg using thermoluminescence phototransferred and optically stimulated luminescence
- Authors: Lontsi Sob, Aaron Joel
- Date: 2022-04-08
- Subjects: Thermoluminescence , Optically stimulated luminescence , Phototransfer , Deep traps , Phototransferred thermoluminescence (PTTL)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294607 , vital:57237 , DOI 10.21504/10962/294607
- Description: The dosimetric features of ∞-Al2O3:C,Mg have been investigated for unannealed and annealed samples. The unannealed sample is referred to as sample A whereas the samples annealed at 700, 900 and 1200°C for 15 minutes each are referred to as samples B, C and D respectively. A glow curve of unannealed ∞-Al2O3:C,Mg measured at 1°C/s after irradiation to 2.0 Gy consists of peaks at 43, 73, 164, 195, 246, 284, 336 and 374°C respectively. For sample B (annealed at 700°C), a glow curve measured at 1°C/s after irradiation to 3.0 Gy has peaks at 46, 76, 100, 170, 199, 290, 330 and 375°C whereas the glow curve of sample C (annealed at 900°C) recorded under the same conditions consists of peaks at 49, 80, 100, 174, 206, 235, 290, 335 and 375°C respectively. Sample D (annealed at 1200°C) is the most sensitive of the four samples. A glow curve of sample D measured at 1°C/s after irradiation to 0.2 Gy has peaks at 52, 82, 102, 174, 234, 288 and 384°C respectively. The peaks are labelled I-VIII in order of appearance. The 100°C peak, labelled IIa, is induced by annealing at or above 700°C. The dose response of these peaks was studied for doses within 0.1-8.2 Gy. The reported peaks follow first-order kinetics irrespective of annealing temperature. Peaks I-III of each sample are reproduced under phototransfer for preheating up to 400°C. For the unannealed sample, the reproduced peaks are labelled A1-A3 whereas for the annealed samples, they are labelled B1-B3, C1-C3 and D1-D3 respectively. The annealing-induced peak at 100°C is reproduced as B2a, C2a and D2a for samples B, C and D respectively. A PTTL peak labelled C2b or D2b is also observed near 140°C in samples C and D. In addition to these PTTL peaks, a PTTL peak corresponding to peak IV is also found for sample D and for the unannealed sample. As the corresponding conventional peaks, the PTTL peaks of each sample follow first-order kinetics. Peak I and its corresponding PTTL peak for each sample are unstable and fade to a minimal level after 300 s of storage time. On the other hand, peak II of each sample and its corresponding PTTL peak could still be observed with delay up to 5000 s. Peak III of the unannealed sample remains stable with storage time up to 48 hours. Irrespective of annealing, the trap corresponding to peak III is the most sensitive to optical stimulation. Time-dependent profiles of PTTL from unannealed and annealed ∞-Al2O3:C,Mg were also studied. The mathematical analysis of the PTTL time-response profiles is based on experimental results. The role of various electron traps in PTTL was determined by using pulse annealing and by monitoring the dependence of peak intensity on duration of illumination for peaks not removed by preheating. The presence and role of deep traps were further demonstrated with thermally assisted optically stimulated luminescence. For the unannealed sample, the activation energy for thermal assistance is 0.033 ± 0.001 eV and the activation energy for thermal i quenching is 1.043 ± 0.001 eV. For sample C, the activation energy for thermal assistance is 0.044 ± 0.003 eV whereas that for thermal quenching is 1.110 ± 0.006 eV. The values for the activation energy for thermal assistance are lower than those reported in literature. Only the values for the activation energy for thermal quenching are somewhat comparable to values reported elsewhere. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2022
- Full Text:
- Authors: Lontsi Sob, Aaron Joel
- Date: 2022-04-08
- Subjects: Thermoluminescence , Optically stimulated luminescence , Phototransfer , Deep traps , Phototransferred thermoluminescence (PTTL)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/294607 , vital:57237 , DOI 10.21504/10962/294607
- Description: The dosimetric features of ∞-Al2O3:C,Mg have been investigated for unannealed and annealed samples. The unannealed sample is referred to as sample A whereas the samples annealed at 700, 900 and 1200°C for 15 minutes each are referred to as samples B, C and D respectively. A glow curve of unannealed ∞-Al2O3:C,Mg measured at 1°C/s after irradiation to 2.0 Gy consists of peaks at 43, 73, 164, 195, 246, 284, 336 and 374°C respectively. For sample B (annealed at 700°C), a glow curve measured at 1°C/s after irradiation to 3.0 Gy has peaks at 46, 76, 100, 170, 199, 290, 330 and 375°C whereas the glow curve of sample C (annealed at 900°C) recorded under the same conditions consists of peaks at 49, 80, 100, 174, 206, 235, 290, 335 and 375°C respectively. Sample D (annealed at 1200°C) is the most sensitive of the four samples. A glow curve of sample D measured at 1°C/s after irradiation to 0.2 Gy has peaks at 52, 82, 102, 174, 234, 288 and 384°C respectively. The peaks are labelled I-VIII in order of appearance. The 100°C peak, labelled IIa, is induced by annealing at or above 700°C. The dose response of these peaks was studied for doses within 0.1-8.2 Gy. The reported peaks follow first-order kinetics irrespective of annealing temperature. Peaks I-III of each sample are reproduced under phototransfer for preheating up to 400°C. For the unannealed sample, the reproduced peaks are labelled A1-A3 whereas for the annealed samples, they are labelled B1-B3, C1-C3 and D1-D3 respectively. The annealing-induced peak at 100°C is reproduced as B2a, C2a and D2a for samples B, C and D respectively. A PTTL peak labelled C2b or D2b is also observed near 140°C in samples C and D. In addition to these PTTL peaks, a PTTL peak corresponding to peak IV is also found for sample D and for the unannealed sample. As the corresponding conventional peaks, the PTTL peaks of each sample follow first-order kinetics. Peak I and its corresponding PTTL peak for each sample are unstable and fade to a minimal level after 300 s of storage time. On the other hand, peak II of each sample and its corresponding PTTL peak could still be observed with delay up to 5000 s. Peak III of the unannealed sample remains stable with storage time up to 48 hours. Irrespective of annealing, the trap corresponding to peak III is the most sensitive to optical stimulation. Time-dependent profiles of PTTL from unannealed and annealed ∞-Al2O3:C,Mg were also studied. The mathematical analysis of the PTTL time-response profiles is based on experimental results. The role of various electron traps in PTTL was determined by using pulse annealing and by monitoring the dependence of peak intensity on duration of illumination for peaks not removed by preheating. The presence and role of deep traps were further demonstrated with thermally assisted optically stimulated luminescence. For the unannealed sample, the activation energy for thermal assistance is 0.033 ± 0.001 eV and the activation energy for thermal i quenching is 1.043 ± 0.001 eV. For sample C, the activation energy for thermal assistance is 0.044 ± 0.003 eV whereas that for thermal quenching is 1.110 ± 0.006 eV. The values for the activation energy for thermal assistance are lower than those reported in literature. Only the values for the activation energy for thermal quenching are somewhat comparable to values reported elsewhere. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2022
- Full Text: