Formulation development, manufacture and evaluation of a lamivudine-zidovudine nano co-crystal thermo-responsive suspension
- Authors: Witika, Bwalya Angel
- Date: 2020
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/140546 , vital:37897 , http://dx.doi.org/10.21504/10962/140546
- Description: Expected release date-April 2021
- Full Text:
- Date Issued: 2020
- Authors: Witika, Bwalya Angel
- Date: 2020
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/140546 , vital:37897 , http://dx.doi.org/10.21504/10962/140546
- Description: Expected release date-April 2021
- Full Text:
- Date Issued: 2020
Genetic connectivity in sandy beach macroinfauna with contrasting life histories and zonation patterns
- Authors: Bezuidenhout, Karien
- Date: 2020
- Subjects: Fishes -- Genetics , Seashore ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/45944 , vital:39380
- Description: Open-ocean sandy beaches are highly dynamic ecosystems that continuously respond to waves, tides and storms. These beaches support a suite of uniquely adapted fauna that exhibits a high degree of endemism. This diversity, which also includes some economically important resource species, contributes to the great socio-economic and ecological value of sandy beach systems, which provide ecosystem services such as nutrient recycling and water purification, fish nursery habitat (surf zone), and natural buffering against storms. Despite their broad global distribution comprising ~70 % of the world’s ice-free coastline, beaches are naturally fragmented by other intertidal marine habitats and extensive coastal development. Sea-level rise is now threatening beaches, particularly along developed coasts through coastal squeeze, with an increased risk of habitat loss and exacerbated fragmentation. Such habitat loss has important implications for population and species persistence, depending on the level of connectivity among populations. While sandy beach macroinfauna tend to be highly mobile across and along shore, they also show a strong bias towards direct, or aplanktonic, development; the latter could reduce opportunities for dispersal and sustained population connectivity. However, comparatively little is known about population connectivity on sandy beaches, limiting scientifically sound management of much of the world’s coastline. This study aims to address this knowledge gap by working towards a conceptual model quantifying population connectivity, and by investigating the specific roles of life history, across-shore zonation, and geographic range as putative indicators and possibly drivers of genetic differentiation (ΦST) and connectivity (gene flow) among beach macroinvertebrate populations. The main hypotheses are that 1) species with a pelagic larval stage will display lower genetic differentiation with higher rates of gene flow among populations than species with a benthic lecithotrophic larval stage or direct development; and 2) genetic differentiation among populations will decrease along an across-shore axis, from the supratidal to the low water mark. Two opposing hypotheses were tested concerning the relationship between genetic structure and distributional range: 3a) Species with a large range (measured as distance and number of latitudes) will show less genetic differentiation than those with a narrow range, because they are more able to disperse; or 3b) more widely distributed species may occur across more phylogenetic | v breaks, and thus show higher genetic differentiation than species restricted to a smaller ranges and single biogeographic provinces. First, the extent and likely drivers of population connectivity were investigated for a suite of temperate South African macroinfauna. Very low, non-significant genetic differentiation was demonstrated for the beach clam Donax serra, thus supporting the hypothesis that pelagic larval dispersers display low/no genetic differentiation among populations (Chapter 2). Statistical power of the COI locus was, however, low in this species, due to reduced genetic variability which could be attributed to an expansion from a small source population into extant habitats. The results highlighted the need for caution when interpreting a lack of genetic differentiation as evidence for population connectivity. Nevertheless, COI sequences verified that D. serra occupying the cool and warm-temperate regions of the South African coast, constitute a single species, despite morphological and behavioural differences between inhabitants of these two bioregions. D. sordidus, a congener of D. serra, and endemic to the warm-temperate (Agulhas) bioregion of South Africa, was investigated to test two opposing hypotheses (Chapter 3): 1) this pelagic larval disperser lack genetic differentiation with high rates of gene flow across its range, or alternatively 2) these clams are genetically structured across their range due to the influence of freshwater input (measured as distance to nearest estuary), and morphodynamics of the surf zone (represented by surf-zone width). Significant global ΦST was estimated for D. sordidus, with differentiation predominantly driven by haplotype frequencies at a single study site and estimates of gene flow among most sample locations generally high. Tentative evidence suggested that natural selection driven by differences in water salinity due to estuarine runoff and surf-zone width, might be maintaining two dominant haplotypes across the range of this species. Beach clams from the Southern Hemisphere, occupying different distributional ranges, were compared to test the hypothesis that genetic structure decreases with an increase in range. This hypothesis was poorly supported by the results; opposite (yet mostly non-significant) trends demonstrated for ΦST and haplotype diversity, thus providing some support for the alternative hypothesis that more phylogeographic breaks in broad-ranging species results in higher estimates of genetic structure in these species.
- Full Text:
- Date Issued: 2020
- Authors: Bezuidenhout, Karien
- Date: 2020
- Subjects: Fishes -- Genetics , Seashore ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/45944 , vital:39380
- Description: Open-ocean sandy beaches are highly dynamic ecosystems that continuously respond to waves, tides and storms. These beaches support a suite of uniquely adapted fauna that exhibits a high degree of endemism. This diversity, which also includes some economically important resource species, contributes to the great socio-economic and ecological value of sandy beach systems, which provide ecosystem services such as nutrient recycling and water purification, fish nursery habitat (surf zone), and natural buffering against storms. Despite their broad global distribution comprising ~70 % of the world’s ice-free coastline, beaches are naturally fragmented by other intertidal marine habitats and extensive coastal development. Sea-level rise is now threatening beaches, particularly along developed coasts through coastal squeeze, with an increased risk of habitat loss and exacerbated fragmentation. Such habitat loss has important implications for population and species persistence, depending on the level of connectivity among populations. While sandy beach macroinfauna tend to be highly mobile across and along shore, they also show a strong bias towards direct, or aplanktonic, development; the latter could reduce opportunities for dispersal and sustained population connectivity. However, comparatively little is known about population connectivity on sandy beaches, limiting scientifically sound management of much of the world’s coastline. This study aims to address this knowledge gap by working towards a conceptual model quantifying population connectivity, and by investigating the specific roles of life history, across-shore zonation, and geographic range as putative indicators and possibly drivers of genetic differentiation (ΦST) and connectivity (gene flow) among beach macroinvertebrate populations. The main hypotheses are that 1) species with a pelagic larval stage will display lower genetic differentiation with higher rates of gene flow among populations than species with a benthic lecithotrophic larval stage or direct development; and 2) genetic differentiation among populations will decrease along an across-shore axis, from the supratidal to the low water mark. Two opposing hypotheses were tested concerning the relationship between genetic structure and distributional range: 3a) Species with a large range (measured as distance and number of latitudes) will show less genetic differentiation than those with a narrow range, because they are more able to disperse; or 3b) more widely distributed species may occur across more phylogenetic | v breaks, and thus show higher genetic differentiation than species restricted to a smaller ranges and single biogeographic provinces. First, the extent and likely drivers of population connectivity were investigated for a suite of temperate South African macroinfauna. Very low, non-significant genetic differentiation was demonstrated for the beach clam Donax serra, thus supporting the hypothesis that pelagic larval dispersers display low/no genetic differentiation among populations (Chapter 2). Statistical power of the COI locus was, however, low in this species, due to reduced genetic variability which could be attributed to an expansion from a small source population into extant habitats. The results highlighted the need for caution when interpreting a lack of genetic differentiation as evidence for population connectivity. Nevertheless, COI sequences verified that D. serra occupying the cool and warm-temperate regions of the South African coast, constitute a single species, despite morphological and behavioural differences between inhabitants of these two bioregions. D. sordidus, a congener of D. serra, and endemic to the warm-temperate (Agulhas) bioregion of South Africa, was investigated to test two opposing hypotheses (Chapter 3): 1) this pelagic larval disperser lack genetic differentiation with high rates of gene flow across its range, or alternatively 2) these clams are genetically structured across their range due to the influence of freshwater input (measured as distance to nearest estuary), and morphodynamics of the surf zone (represented by surf-zone width). Significant global ΦST was estimated for D. sordidus, with differentiation predominantly driven by haplotype frequencies at a single study site and estimates of gene flow among most sample locations generally high. Tentative evidence suggested that natural selection driven by differences in water salinity due to estuarine runoff and surf-zone width, might be maintaining two dominant haplotypes across the range of this species. Beach clams from the Southern Hemisphere, occupying different distributional ranges, were compared to test the hypothesis that genetic structure decreases with an increase in range. This hypothesis was poorly supported by the results; opposite (yet mostly non-significant) trends demonstrated for ΦST and haplotype diversity, thus providing some support for the alternative hypothesis that more phylogeographic breaks in broad-ranging species results in higher estimates of genetic structure in these species.
- Full Text:
- Date Issued: 2020
Girls here and boys there : participatory visual methodology as pedagogy to facilitate gender sensitive practices with pre-service foundation phase teachers
- Authors: Notshulwana, Robin Anne
- Date: 2020
- Subjects: Gender identity -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/49385 , vital:41700
- Description: This study explores how participatory visual methodology (PVM) might facilitate a deeper understanding of gender sensitive practices (GSP) in Foundation Phase (FP) pre-service teachers. Foundation Phase classrooms are not impervious to unequal gender practices and despite policies that promote gender equitable practices in schools and in society in general, most South African schools still engage in gendered practices that perpetuate inequality and gender based violence (GBV). While the topic of gender currently features in a South African university FP curriculum with the intention of promoting social justice, the pedagogy used to enable pre-service FP teachers to understand how gender works in schools seems to do nothing more than describe the problem and give cursory suggestions for creating gender equitable practices. Teachers are often unaware of how their own gendered identity influences their facilitation of the curriculum in a gendered way. This is important in South Africa, where gender inequality remains a problem and GBV is rife. This study adopted a qualitative approach and is located within the critical paradigm applying the principles of PVM. It drew on feminist poststructuralism and feminist pedagogy as theoretical lenses to frame the study and to make meaning of the data. Participants in the study were five female pre-service FP teachers who were purposively selected. Data were generated through the visual methods of family photo album, drawing and participatory video, which were first analysed using participatory analysis, and then using thematic analysis. The main purpose of the research was to explore how PVM can facilitate a deeper awareness of GSP in pre-service FP teachers. The secondary aim was to explore their understandings of gender and GSP and how these understandings might facilitate or inhibit GSP among pre-service FP teachers. The pre-service FP teachers’ understandings of gender were elicited using the self as an entry point to explore their own gendered identities which demonstrated their somewhat narrow understanding of how gender is reified in society through mechanisms such as dress and particular performances. They further understood that their own gendered selves can shift and change with time and context. Their understanding of gender further informed their understanding of GSP. The pre-service FP teachers understood GSP as going beyond interchanging roles of girls and boys and that it meant constantly engaging with their own understandings of gender; to review their constructions of FP learners, to see pedagogical moments to teach gender sensitivity, and to recognise that GSP extends beyond the classroom. Finally, the pre-service FP teachers articulated the circumstances that might enable or inhibit their GSP in their classrooms. They recognised how the powerful constructions of gender in a society influence their work, and how, in turn their work might influence society. This translated into them understanding how the ethos of the school might mirror and sustain the hegemonic discourse of society and at the same time how they might begin to question and disrupt the discourse sustained in school. The teacher education programme, with a vested interest in gender equality, is an important mechanism to begin disrupting hegemonic discourses perpetuated in schools. The findings suggest that through its potential for reflexivity and criticality, PVM enabled the pre-service FP teachers to see how their constructions of gender influence their own practices in schools. The findings have implications for FP teacher education programmes in the South African context. Faculties of education could revisit their curriculum to ensure that gender is infused throughout the curriculum, but more importantly, could consider ‘starting with the self’ (Kirk, 2009) as an impetus to learn about how gender is reified in society and in schools. In doing so, faculties of education could also consider tools of analysis such as a feminist poststructural theory to enable the pre-service FP teachers to deepen their understandings but also support the potential to articulate and make meaning of their experiences. Teacher educators could revisit their curriculum content to determine whether the content might perpetuate a narrow view of learning and learners especially with regards to gender and considering pedagogical choices that develop pre-service teachers’ ability to cultivate classroom environments that promote gender equality. Starting with the self is an entry point for pre-service FP teachers to examine their own understanding of gender and see how this might enable GSP in their professional work. PVM, aligned with a feminist pedagogy and feminist poststructuralism, facilitated such a process.
- Full Text:
- Date Issued: 2020
- Authors: Notshulwana, Robin Anne
- Date: 2020
- Subjects: Gender identity -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/49385 , vital:41700
- Description: This study explores how participatory visual methodology (PVM) might facilitate a deeper understanding of gender sensitive practices (GSP) in Foundation Phase (FP) pre-service teachers. Foundation Phase classrooms are not impervious to unequal gender practices and despite policies that promote gender equitable practices in schools and in society in general, most South African schools still engage in gendered practices that perpetuate inequality and gender based violence (GBV). While the topic of gender currently features in a South African university FP curriculum with the intention of promoting social justice, the pedagogy used to enable pre-service FP teachers to understand how gender works in schools seems to do nothing more than describe the problem and give cursory suggestions for creating gender equitable practices. Teachers are often unaware of how their own gendered identity influences their facilitation of the curriculum in a gendered way. This is important in South Africa, where gender inequality remains a problem and GBV is rife. This study adopted a qualitative approach and is located within the critical paradigm applying the principles of PVM. It drew on feminist poststructuralism and feminist pedagogy as theoretical lenses to frame the study and to make meaning of the data. Participants in the study were five female pre-service FP teachers who were purposively selected. Data were generated through the visual methods of family photo album, drawing and participatory video, which were first analysed using participatory analysis, and then using thematic analysis. The main purpose of the research was to explore how PVM can facilitate a deeper awareness of GSP in pre-service FP teachers. The secondary aim was to explore their understandings of gender and GSP and how these understandings might facilitate or inhibit GSP among pre-service FP teachers. The pre-service FP teachers’ understandings of gender were elicited using the self as an entry point to explore their own gendered identities which demonstrated their somewhat narrow understanding of how gender is reified in society through mechanisms such as dress and particular performances. They further understood that their own gendered selves can shift and change with time and context. Their understanding of gender further informed their understanding of GSP. The pre-service FP teachers understood GSP as going beyond interchanging roles of girls and boys and that it meant constantly engaging with their own understandings of gender; to review their constructions of FP learners, to see pedagogical moments to teach gender sensitivity, and to recognise that GSP extends beyond the classroom. Finally, the pre-service FP teachers articulated the circumstances that might enable or inhibit their GSP in their classrooms. They recognised how the powerful constructions of gender in a society influence their work, and how, in turn their work might influence society. This translated into them understanding how the ethos of the school might mirror and sustain the hegemonic discourse of society and at the same time how they might begin to question and disrupt the discourse sustained in school. The teacher education programme, with a vested interest in gender equality, is an important mechanism to begin disrupting hegemonic discourses perpetuated in schools. The findings suggest that through its potential for reflexivity and criticality, PVM enabled the pre-service FP teachers to see how their constructions of gender influence their own practices in schools. The findings have implications for FP teacher education programmes in the South African context. Faculties of education could revisit their curriculum to ensure that gender is infused throughout the curriculum, but more importantly, could consider ‘starting with the self’ (Kirk, 2009) as an impetus to learn about how gender is reified in society and in schools. In doing so, faculties of education could also consider tools of analysis such as a feminist poststructural theory to enable the pre-service FP teachers to deepen their understandings but also support the potential to articulate and make meaning of their experiences. Teacher educators could revisit their curriculum content to determine whether the content might perpetuate a narrow view of learning and learners especially with regards to gender and considering pedagogical choices that develop pre-service teachers’ ability to cultivate classroom environments that promote gender equality. Starting with the self is an entry point for pre-service FP teachers to examine their own understanding of gender and see how this might enable GSP in their professional work. PVM, aligned with a feminist pedagogy and feminist poststructuralism, facilitated such a process.
- Full Text:
- Date Issued: 2020
History on trial: a study of the Salem commonage land claim
- Authors: Bezuidenhout, GJW
- Date: 2020
- Subjects: South Africa. Restitution of Land Rights Act, 1994 , Salem (South Africa) -- History , Land tenure -- Law and legilstion -- South Africa , Land reform -- Law and legislation -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146647 , vital:38545
- Description: This thesis critically examines the Salem commonage claim, a dispute that has shaken the hamlet of Salem to its core. On ground level it has caused racialized fault lines to reopen, while suspicion and distrust has also grown between the black Africans of the area as well. On a national level, the Constitutional Court judgement has potentially set a precedent with regards to its jurisprudential approach in determining the validity of land claims in South Africa. Its interpretation of the law was determined by the restorative justice jurisprudence enshrined in the Restitution of Land Rights Act 22 of 1994 (the Act). It based its own understanding of the history of the commonage on this jurisprudence. In a bold step towards realising the aims and purposes of the Act, the Constitutional Court found that both the black African claimants as well as the white landowners have equal rights to the land. One of the reasons why the decision of the Constitutional Court is ground-breaking is that the dispute involves a former commonage – land used for common purpose. The Constitutional Court emphasised that the Act was an “extraordinary piece of legislation” and had to be interpreted in such a way so as to address the injustices of the past. This included provisions of the Act which dealt with how oral testimonies from claimants would be dealt with. Another interesting feature was the heavy reliance by all parties on expert witnesses in the persons of eminent historians, Professors Martin Legassick and Herman Giliomee. This case gave much-needed clarification as to what the appropriate role of an expert historian witness may be in a land claim. The success or failure of land claims often depend on the weight of the evidence supplied by the expert historian witness. But the historian must also take cognisance of the fact that the evidence s/he gives is appropriate according to the scope of law. This case also dismisses the assumption that colonial instruments of land assignation are beyond reproach. These instruments which grant rights to land may also be scrutinised in a court of law, just like when oral testimony is tested for its credibility. This is important to note, especially when balancing land rights of the claimants against those of the landowners. This thesis agrees with the decision taken by the Constitutional Court in this instance. However, it also cautions that such softly-softly approaches may appear as a suitable compromise on paper, but the feeling on the ground may not be as receptive to reconciliation as what the courts would have hoped for. To the jurist, this judgement accurately encapsulates the purpose and aims of the Act. However, such a judgement may not seem satisfactory to the people of Salem. The decisions of the Salem commonage case are sure to inform the discourse of land claims in South Africa.
- Full Text:
- Date Issued: 2020
- Authors: Bezuidenhout, GJW
- Date: 2020
- Subjects: South Africa. Restitution of Land Rights Act, 1994 , Salem (South Africa) -- History , Land tenure -- Law and legilstion -- South Africa , Land reform -- Law and legislation -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146647 , vital:38545
- Description: This thesis critically examines the Salem commonage claim, a dispute that has shaken the hamlet of Salem to its core. On ground level it has caused racialized fault lines to reopen, while suspicion and distrust has also grown between the black Africans of the area as well. On a national level, the Constitutional Court judgement has potentially set a precedent with regards to its jurisprudential approach in determining the validity of land claims in South Africa. Its interpretation of the law was determined by the restorative justice jurisprudence enshrined in the Restitution of Land Rights Act 22 of 1994 (the Act). It based its own understanding of the history of the commonage on this jurisprudence. In a bold step towards realising the aims and purposes of the Act, the Constitutional Court found that both the black African claimants as well as the white landowners have equal rights to the land. One of the reasons why the decision of the Constitutional Court is ground-breaking is that the dispute involves a former commonage – land used for common purpose. The Constitutional Court emphasised that the Act was an “extraordinary piece of legislation” and had to be interpreted in such a way so as to address the injustices of the past. This included provisions of the Act which dealt with how oral testimonies from claimants would be dealt with. Another interesting feature was the heavy reliance by all parties on expert witnesses in the persons of eminent historians, Professors Martin Legassick and Herman Giliomee. This case gave much-needed clarification as to what the appropriate role of an expert historian witness may be in a land claim. The success or failure of land claims often depend on the weight of the evidence supplied by the expert historian witness. But the historian must also take cognisance of the fact that the evidence s/he gives is appropriate according to the scope of law. This case also dismisses the assumption that colonial instruments of land assignation are beyond reproach. These instruments which grant rights to land may also be scrutinised in a court of law, just like when oral testimony is tested for its credibility. This is important to note, especially when balancing land rights of the claimants against those of the landowners. This thesis agrees with the decision taken by the Constitutional Court in this instance. However, it also cautions that such softly-softly approaches may appear as a suitable compromise on paper, but the feeling on the ground may not be as receptive to reconciliation as what the courts would have hoped for. To the jurist, this judgement accurately encapsulates the purpose and aims of the Act. However, such a judgement may not seem satisfactory to the people of Salem. The decisions of the Salem commonage case are sure to inform the discourse of land claims in South Africa.
- Full Text:
- Date Issued: 2020
How to do things with speeches: a critical discourse analysis of military coup texts in Nigeria
- Authors: Bello, Umar
- Date: 2020
- Subjects: Speeches, addresses, etc., Nigerian -- 20th century -- History and criticism , Critical discourse analysis -- Nigeria , Corpora (Linguistics) , Social sciences -- Philosophy , Intertextuality , Interpellation -- Nigeria , Forensics (Public speaking) , Oratory -- Nigeria , Nigeria -- Politics and government -- 1960- , Nigeria -- Social conditions -- 1960-
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/143336 , vital:38234
- Description: Coup speeches that usher the military into political power in Nigeria are the central focus of this thesis. There are seven coup speeches that are notable in the changing of the political course in Nigeria and in enabling the military to rule Nigeria for 30 years, establishing another alternative political construct and party (Bangura 1991). The seven coup speeches along with two others, one a colonial proclamation of conquest and the other a counter coup speech (altogether making nine) constitute the data of this thesis. The analysis done here uses Critical Discourse Analysis, based on a combination of Fairclough (1989, 2001), Fairclough and Fairclough (2012), Thompson’s (1984, 1988 and 1990) works with complementary insights by Chilton (2004), to analyze the speeches in order to understand the ideologies, perceptions and arguments of the coup makers enshrined in the texts. I also employ a concordance analytic system in corpus linguistics to sort uses of important terms and lexical items. The analysis is divided into three broad parts, namely: an analysis of representation of social actors and their action, an analysis of the processes of interpellation and then an analysis of the premises of the arguments contained in the speeches. In the concluding part, there is a discussion of the dialectical nature of the coup speeches especially in the areas of mutual influences which aids in the gradual sedimentation of the political ideology of the military. In particular, there is a longitudinal intertextual analysis across all the speeches, from the earliest to the latest, to see how a coup speech genre is created. The contribution of this work to knowledge is in terms of combining discourse analysis and social theory to illuminate some aspects of Nigeria’s socio- political crises in depth and multifariously. This work helps in understanding the nature of Nigerian autocratic democracy, subservient followership by the citizenry and the supremacy of the military elite. The work employs a novel combination of representation, argumentation, interpellation and constitutive intertextuality in understanding military discourse. It looks at speaker intention, the exploitation of interpretation or reception and the formation of subjects in general and each with its importance and social context. The work as a whole reveals that the military try to build legitimacy by way of establishing authority through rhetorical arguments in varying degrees. These arguments are laid bare, and what they discern is that charges are decidedly trumped up by the military against their opponents and constructed to suit the spin of their moments. The coup makers in some instances construct strawmen of opponents and then go ahead to attack their constructed assumptions or they charge without substance using nominalizations, metaphorical constructions and presuppositions. They apply stipulative definitions and emotionally loaded words in evaluating their actions favourably and also in the negative evaluation of the actions of the opponents. At the level of interpellational analysis, the data reveals the use of language in gradually hailing the citizens as military subjects. The role of the audience changes here i.e. from those to be convinced in rhetorical evaluation of opponents to those to be firmly controlled. The persistent hailing and positioning of the citizens as military subjects help in concretizing their subjecthood. The reaction of the people in affirmation of support to the rule of the military is crucial and it completes the interpellation process. As observed by Clark (2007, 141) “many African societies are so inured to military intervention as not to regard it as aberrant”. This inuring of the societies has to do with hegemonic ideological practices in military discourses claiming legitimacy and the right to rule. At the reception level, this shows that most of the citizens have bought into the dominant ideology and are as such interpellated by it or have adopted what Hall (2015, 125) would call the ‘dominant-hegemonic position’. Aspects of argumentation, speech acts, and deontic modals used by the coup makers help in gradually solidifying the subservient nature of the citizens to the military junta. The diachronic and intertextual nature of the analysis also reveals that the colonial proclamation of conquest in Nigeria by Lord Fredrick Lugard possibly influenced the first coup speech in 1966 in terms of structure and genre. There are traces of the colonial proclamations found in the 1966 coup speech. In substance, the military appear to copy their colonial progenitors. Historically, the military were formed as an army of colonial conquest. There is a dialectical interplay between colonial discourse and military coup speeches. The first coup speech, for its part, influences other coup speeches and they in general impact on civilian political language. The work analyzes from the minute to the global and in this bid unties the layers of assumptions, constructions and points of views that underpin an otherwise objective presentation of reality. The study also engages social theory in illuminating aspects of discourse, social practice and political action. The works of post-structuralists like Foucault, Althusser, Bourdieu, Habermas, Laclau and Mouffe, Derrida etc. are employed in shedding light on the processes of social formation in the interpellation of subjects and in the construction of a new political authority by the military regimes.
- Full Text:
- Date Issued: 2020
- Authors: Bello, Umar
- Date: 2020
- Subjects: Speeches, addresses, etc., Nigerian -- 20th century -- History and criticism , Critical discourse analysis -- Nigeria , Corpora (Linguistics) , Social sciences -- Philosophy , Intertextuality , Interpellation -- Nigeria , Forensics (Public speaking) , Oratory -- Nigeria , Nigeria -- Politics and government -- 1960- , Nigeria -- Social conditions -- 1960-
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/143336 , vital:38234
- Description: Coup speeches that usher the military into political power in Nigeria are the central focus of this thesis. There are seven coup speeches that are notable in the changing of the political course in Nigeria and in enabling the military to rule Nigeria for 30 years, establishing another alternative political construct and party (Bangura 1991). The seven coup speeches along with two others, one a colonial proclamation of conquest and the other a counter coup speech (altogether making nine) constitute the data of this thesis. The analysis done here uses Critical Discourse Analysis, based on a combination of Fairclough (1989, 2001), Fairclough and Fairclough (2012), Thompson’s (1984, 1988 and 1990) works with complementary insights by Chilton (2004), to analyze the speeches in order to understand the ideologies, perceptions and arguments of the coup makers enshrined in the texts. I also employ a concordance analytic system in corpus linguistics to sort uses of important terms and lexical items. The analysis is divided into three broad parts, namely: an analysis of representation of social actors and their action, an analysis of the processes of interpellation and then an analysis of the premises of the arguments contained in the speeches. In the concluding part, there is a discussion of the dialectical nature of the coup speeches especially in the areas of mutual influences which aids in the gradual sedimentation of the political ideology of the military. In particular, there is a longitudinal intertextual analysis across all the speeches, from the earliest to the latest, to see how a coup speech genre is created. The contribution of this work to knowledge is in terms of combining discourse analysis and social theory to illuminate some aspects of Nigeria’s socio- political crises in depth and multifariously. This work helps in understanding the nature of Nigerian autocratic democracy, subservient followership by the citizenry and the supremacy of the military elite. The work employs a novel combination of representation, argumentation, interpellation and constitutive intertextuality in understanding military discourse. It looks at speaker intention, the exploitation of interpretation or reception and the formation of subjects in general and each with its importance and social context. The work as a whole reveals that the military try to build legitimacy by way of establishing authority through rhetorical arguments in varying degrees. These arguments are laid bare, and what they discern is that charges are decidedly trumped up by the military against their opponents and constructed to suit the spin of their moments. The coup makers in some instances construct strawmen of opponents and then go ahead to attack their constructed assumptions or they charge without substance using nominalizations, metaphorical constructions and presuppositions. They apply stipulative definitions and emotionally loaded words in evaluating their actions favourably and also in the negative evaluation of the actions of the opponents. At the level of interpellational analysis, the data reveals the use of language in gradually hailing the citizens as military subjects. The role of the audience changes here i.e. from those to be convinced in rhetorical evaluation of opponents to those to be firmly controlled. The persistent hailing and positioning of the citizens as military subjects help in concretizing their subjecthood. The reaction of the people in affirmation of support to the rule of the military is crucial and it completes the interpellation process. As observed by Clark (2007, 141) “many African societies are so inured to military intervention as not to regard it as aberrant”. This inuring of the societies has to do with hegemonic ideological practices in military discourses claiming legitimacy and the right to rule. At the reception level, this shows that most of the citizens have bought into the dominant ideology and are as such interpellated by it or have adopted what Hall (2015, 125) would call the ‘dominant-hegemonic position’. Aspects of argumentation, speech acts, and deontic modals used by the coup makers help in gradually solidifying the subservient nature of the citizens to the military junta. The diachronic and intertextual nature of the analysis also reveals that the colonial proclamation of conquest in Nigeria by Lord Fredrick Lugard possibly influenced the first coup speech in 1966 in terms of structure and genre. There are traces of the colonial proclamations found in the 1966 coup speech. In substance, the military appear to copy their colonial progenitors. Historically, the military were formed as an army of colonial conquest. There is a dialectical interplay between colonial discourse and military coup speeches. The first coup speech, for its part, influences other coup speeches and they in general impact on civilian political language. The work analyzes from the minute to the global and in this bid unties the layers of assumptions, constructions and points of views that underpin an otherwise objective presentation of reality. The study also engages social theory in illuminating aspects of discourse, social practice and political action. The works of post-structuralists like Foucault, Althusser, Bourdieu, Habermas, Laclau and Mouffe, Derrida etc. are employed in shedding light on the processes of social formation in the interpellation of subjects and in the construction of a new political authority by the military regimes.
- Full Text:
- Date Issued: 2020
Ichthyofaunal and isotope changes along the rivere-stuarine continuum in a fluvially dominated Southern African coastal system
- Authors: Nashima, Festus Panduleni
- Date: 2020
- Subjects: Fishes -- Ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/48555 , vital:40890
- Description: Catchment to coast and the continuum concept recognize linkages and make it imperative to take an ecosystem approach to catchment management, water allocation, fisheries management and environmental management as a whole. Fishes that utilise estuarine environments are influenced by physical and chemical conditions as well as biological interactions. Community structure, drivers and trophic linkages between species of different origin, utilising the low salinity waters along the riverestuarine continuum remain poorly understood in the lower Orange River and estuary. This body of work investigated the spatio-temporal dynamics structuring fishes in the lower Orange River Estuary Continuum (OREC) within the context of River Continuum (Vannote et al., 1980). Eight years (2004 - 2018) of seasonal sampling at 18 sites comprised of multi-species catches were analysed, including three years (2016 - 2018) exploring trophic linkages between the dominant species of marine, estuarine and freshwater fishes in the system. In total, 30 species belonging to 16 families were collected in the lower OREC. The Family Mugilidae dominated all catches. Fish species composition was comprised mostly of freshwater (47%), followed by the marine (33%) and estuarine species (20%). Numerically, the marine euryhaline Chelon richardsonii and solely estuarine Gilchristella aestuaria were the dominant species in the estuary region (site 1 - 11) with 95% and 4% contribution, respectively. Chelon richardsonii also dominated all catches (67%) upstream into the river (site 12 - 18), followed by freshwater Labeobarbus aeneus (13%) and Pseudocrenilabrus philander (8%). This highlights the point that besides the marine Chelon richardsonii, other species albeit marine, estuarine and freshwater are utilising unique areas within the OREC. Temporal differentiation in fish abundance (catch-per-unit-effort, CPUE), diversity, richness and evenness were higher in the high-flow season than the low-flow season. Mean CPUE was higher at the mouth of the estuary and declined upstream into the river, whilst species diversity (including richness and evenness) increased upstream. High catches but low species diversity observed close to the mouth of the estuary were attributed to the domination of Chelon richardsonii. However, species diversity increased upstream in the river due to the dominance of freshwater fishes coupled with several marine and estuarine species. This diversity patterns were inconsistent with the general Remane and revised model for estuaries, hence a new RiverEstuarine Continuum concept suitable for OREC was developed. With the exception of Chelon richardsonii, spatial variability in the length-frequency distribution of most fishes was observed. Physico-chemical drivers provided valuable information on adaptation limits of species movement and distribution. Fishes were structured along a salinity gradient and interaction between temperature and salinity influenced community structure and diversity patterns in the OREC. Fish species utilising the lower OREC are predominantly zoobenthivores but a few detritivores/planktivores dominate numerically. Trophic inferences from stable isotope analysis showed increased carbon isotope values (δ 13C) with salinity toward the mouth of the estuary, whilst nitrogen isotope values (δ 15N) increased upstream into the river. Ontogenetic shifts in the SI ratios of all five fish species (marine Chelon richardsonii; estuarine Gilchristella aestuaria; freshwater Labeobarbus aeneus, Pseudocrenilabrus philander and Mesobola brevianalis) were observed in the OREC. Variability in seasons and salinity gradient influenced the SI ratios of several fish species. Seasonal changes influenced the δ 13C ratios of all species, except for Labeobarbus aeneus and Pseudocrenilabrus philander whereas the δ 15N ratios of all species (except for Mesobola brevianalis) differed significantly between the high-flow and low-flow season. This can be due to their feeding on specific life-history stages, such as eggs, larvae, gametophytes, sporophytes or zoospores of prey. Stable isotope ratios revealed that Mesobola brevianalis fed at a higher trophic level than Chelon richardsonii and Gilchristella aestuaria. Mesobola brevianalis feed on planktonic crustacean and insects. Chelon richardsonii feed on a wide range of prey, with prey switching between planktonic and detritivore food resources, whilst Gilchristella aestuaria feed selectively on zooplankton but switched to filter feeding modes in turbid water. Generally, δ 15N SI ratios increase with growth, however, for Labeobarbus aeneus, it was significantly higher in small size length than in large size individuals, probably because most of the juveniles assessed were caught upstream where δ 15N increases. Juveniles of Labeobarbus aeneus mainly feed on zoobenthos whilst in larger fish phytoplankton becomes increasingly important, suggesting the possibility that zoobenthos was more 15N enriched than plant materials. The trophic niches of Mesobola brevianalis were isotopically distinguishable from Chelon richardsonii and Gilchristella aestuaria during the low-flow season, revealing that these species are probably accessing carbon sources from different food chains. During high-flow season, the isotopic niche overlapped among several species, indicating that these species are probably deriving carbon sources from the same or similar food chains. Results from Layman isotope-based metrics revealed that Chelon richardsonii, Pseudocrenilabrus philander and Labeobarbus aeneus occupied the widest isotopic niche in the lower OREC, suggesting that these species are utilising food sources which may be derived from a wide variety of carbon sources. Mesobola brevianalis had the narrowest isotopic niche, however this does not imply "a narrow range of food sources’’ for the species. Overall, the potential carbon sources for selected fish species revealed that they are supported by a variety of food sources (mainly phyto-and zooplanktonic) or their food items constituted different basal sources which enable them to coexist. This study represents the first, integrated investigation of trophic relations among fishes of different origin using δ 13C and δ15N SI analyses. The current study provides a broader understanding of fish ecology within the River-Estuarine Continuum in the lower Orange River and estuary. By filling research gaps identified in the lower OREC, this synthesis of work also supports and informs management, conservation and responsible utilisation of estuarine fishery resources, in particular within the OREC.
- Full Text:
- Date Issued: 2020
- Authors: Nashima, Festus Panduleni
- Date: 2020
- Subjects: Fishes -- Ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/48555 , vital:40890
- Description: Catchment to coast and the continuum concept recognize linkages and make it imperative to take an ecosystem approach to catchment management, water allocation, fisheries management and environmental management as a whole. Fishes that utilise estuarine environments are influenced by physical and chemical conditions as well as biological interactions. Community structure, drivers and trophic linkages between species of different origin, utilising the low salinity waters along the riverestuarine continuum remain poorly understood in the lower Orange River and estuary. This body of work investigated the spatio-temporal dynamics structuring fishes in the lower Orange River Estuary Continuum (OREC) within the context of River Continuum (Vannote et al., 1980). Eight years (2004 - 2018) of seasonal sampling at 18 sites comprised of multi-species catches were analysed, including three years (2016 - 2018) exploring trophic linkages between the dominant species of marine, estuarine and freshwater fishes in the system. In total, 30 species belonging to 16 families were collected in the lower OREC. The Family Mugilidae dominated all catches. Fish species composition was comprised mostly of freshwater (47%), followed by the marine (33%) and estuarine species (20%). Numerically, the marine euryhaline Chelon richardsonii and solely estuarine Gilchristella aestuaria were the dominant species in the estuary region (site 1 - 11) with 95% and 4% contribution, respectively. Chelon richardsonii also dominated all catches (67%) upstream into the river (site 12 - 18), followed by freshwater Labeobarbus aeneus (13%) and Pseudocrenilabrus philander (8%). This highlights the point that besides the marine Chelon richardsonii, other species albeit marine, estuarine and freshwater are utilising unique areas within the OREC. Temporal differentiation in fish abundance (catch-per-unit-effort, CPUE), diversity, richness and evenness were higher in the high-flow season than the low-flow season. Mean CPUE was higher at the mouth of the estuary and declined upstream into the river, whilst species diversity (including richness and evenness) increased upstream. High catches but low species diversity observed close to the mouth of the estuary were attributed to the domination of Chelon richardsonii. However, species diversity increased upstream in the river due to the dominance of freshwater fishes coupled with several marine and estuarine species. This diversity patterns were inconsistent with the general Remane and revised model for estuaries, hence a new RiverEstuarine Continuum concept suitable for OREC was developed. With the exception of Chelon richardsonii, spatial variability in the length-frequency distribution of most fishes was observed. Physico-chemical drivers provided valuable information on adaptation limits of species movement and distribution. Fishes were structured along a salinity gradient and interaction between temperature and salinity influenced community structure and diversity patterns in the OREC. Fish species utilising the lower OREC are predominantly zoobenthivores but a few detritivores/planktivores dominate numerically. Trophic inferences from stable isotope analysis showed increased carbon isotope values (δ 13C) with salinity toward the mouth of the estuary, whilst nitrogen isotope values (δ 15N) increased upstream into the river. Ontogenetic shifts in the SI ratios of all five fish species (marine Chelon richardsonii; estuarine Gilchristella aestuaria; freshwater Labeobarbus aeneus, Pseudocrenilabrus philander and Mesobola brevianalis) were observed in the OREC. Variability in seasons and salinity gradient influenced the SI ratios of several fish species. Seasonal changes influenced the δ 13C ratios of all species, except for Labeobarbus aeneus and Pseudocrenilabrus philander whereas the δ 15N ratios of all species (except for Mesobola brevianalis) differed significantly between the high-flow and low-flow season. This can be due to their feeding on specific life-history stages, such as eggs, larvae, gametophytes, sporophytes or zoospores of prey. Stable isotope ratios revealed that Mesobola brevianalis fed at a higher trophic level than Chelon richardsonii and Gilchristella aestuaria. Mesobola brevianalis feed on planktonic crustacean and insects. Chelon richardsonii feed on a wide range of prey, with prey switching between planktonic and detritivore food resources, whilst Gilchristella aestuaria feed selectively on zooplankton but switched to filter feeding modes in turbid water. Generally, δ 15N SI ratios increase with growth, however, for Labeobarbus aeneus, it was significantly higher in small size length than in large size individuals, probably because most of the juveniles assessed were caught upstream where δ 15N increases. Juveniles of Labeobarbus aeneus mainly feed on zoobenthos whilst in larger fish phytoplankton becomes increasingly important, suggesting the possibility that zoobenthos was more 15N enriched than plant materials. The trophic niches of Mesobola brevianalis were isotopically distinguishable from Chelon richardsonii and Gilchristella aestuaria during the low-flow season, revealing that these species are probably accessing carbon sources from different food chains. During high-flow season, the isotopic niche overlapped among several species, indicating that these species are probably deriving carbon sources from the same or similar food chains. Results from Layman isotope-based metrics revealed that Chelon richardsonii, Pseudocrenilabrus philander and Labeobarbus aeneus occupied the widest isotopic niche in the lower OREC, suggesting that these species are utilising food sources which may be derived from a wide variety of carbon sources. Mesobola brevianalis had the narrowest isotopic niche, however this does not imply "a narrow range of food sources’’ for the species. Overall, the potential carbon sources for selected fish species revealed that they are supported by a variety of food sources (mainly phyto-and zooplanktonic) or their food items constituted different basal sources which enable them to coexist. This study represents the first, integrated investigation of trophic relations among fishes of different origin using δ 13C and δ15N SI analyses. The current study provides a broader understanding of fish ecology within the River-Estuarine Continuum in the lower Orange River and estuary. By filling research gaps identified in the lower OREC, this synthesis of work also supports and informs management, conservation and responsible utilisation of estuarine fishery resources, in particular within the OREC.
- Full Text:
- Date Issued: 2020
Identifying a Successful Accounting Student: Profiling of Postgraduate Accounting Students in the Eastern Cape
- Authors: Weldon, Lana Joy
- Date: 2020
- Subjects: Personality -- South Africa -- Eastern Cape , Accounting -- Study and teaching (Higher) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/50699 , vital:42343
- Description: Throughput rates and transformation have long been considered major challenges to accounting departments in South Africa. While much research has been done on various aspects of study techniques in an attempt to assist students to succeed, little attention has been paid to profiling students to ascertain whether there are common traits in terms of personality, aptitude, values and motives, which distinguish successful students from others. This study looks at these factors and uses sub-tests of the Differential Aptitude Test (DAT), selected with reference to the South African Institute of Chartered Accountants (SAICA) Competency Framework, to determine the correlation between these aptitudes and the success of accounting students. In addition, the impact of biographical data, including gender, race and type of school attended, is considered on the success of the students and the individual sub-tests of aptitude. The study then considers the impact of various personality types, personality traits and values on the success or failure of accounting students, and finally seeks to ascertain whether there is a holistic profile of a student who has a statistically significant chance of succeeding in accounting studies. Results indicate that the sub-tests of aptitude for verbal reasoning and reading comprehension have the most significance in predicting student success and that gender and race have a medium effect. Furthermore, personality types, personality traits and values do not have a significant impact on student success. The only biographical factor to have an impact on success was race. Despite the findings in the individual factors considered, no distinct personality profile of a successful Results indicate that the sub-tests of aptitude for verbal reasoning and reading comprehension have the most significance in predicting student success and that gender and race have a medium effect. Furthermore, personality types, personality traits and values do not have a significant impact on student success. The only biographical factor to have an impact on success was race. Despite the findings in the individual factors considered, no distinct personality profile of a successful accounting student emerged. Future research on the use of literacy competency assessments in the admission requirements for chartered accounting programmes, or to inform student academic support initiatives is recommended. accounting student emerged. Future research on the use of literacy competency assessments in the admission requirements for chartered accounting programmes, or to inform student academic support initiatives is recommended.
- Full Text:
- Date Issued: 2020
- Authors: Weldon, Lana Joy
- Date: 2020
- Subjects: Personality -- South Africa -- Eastern Cape , Accounting -- Study and teaching (Higher) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/50699 , vital:42343
- Description: Throughput rates and transformation have long been considered major challenges to accounting departments in South Africa. While much research has been done on various aspects of study techniques in an attempt to assist students to succeed, little attention has been paid to profiling students to ascertain whether there are common traits in terms of personality, aptitude, values and motives, which distinguish successful students from others. This study looks at these factors and uses sub-tests of the Differential Aptitude Test (DAT), selected with reference to the South African Institute of Chartered Accountants (SAICA) Competency Framework, to determine the correlation between these aptitudes and the success of accounting students. In addition, the impact of biographical data, including gender, race and type of school attended, is considered on the success of the students and the individual sub-tests of aptitude. The study then considers the impact of various personality types, personality traits and values on the success or failure of accounting students, and finally seeks to ascertain whether there is a holistic profile of a student who has a statistically significant chance of succeeding in accounting studies. Results indicate that the sub-tests of aptitude for verbal reasoning and reading comprehension have the most significance in predicting student success and that gender and race have a medium effect. Furthermore, personality types, personality traits and values do not have a significant impact on student success. The only biographical factor to have an impact on success was race. Despite the findings in the individual factors considered, no distinct personality profile of a successful Results indicate that the sub-tests of aptitude for verbal reasoning and reading comprehension have the most significance in predicting student success and that gender and race have a medium effect. Furthermore, personality types, personality traits and values do not have a significant impact on student success. The only biographical factor to have an impact on success was race. Despite the findings in the individual factors considered, no distinct personality profile of a successful accounting student emerged. Future research on the use of literacy competency assessments in the admission requirements for chartered accounting programmes, or to inform student academic support initiatives is recommended. accounting student emerged. Future research on the use of literacy competency assessments in the admission requirements for chartered accounting programmes, or to inform student academic support initiatives is recommended.
- Full Text:
- Date Issued: 2020
Impact of climate finance on environmental quality in Sub-Sahara Africa
- Authors: Doku, Isaac
- Date: 2020
- Subjects: Climatic changes -- Economic aspects , Economic development -- Environmental aspects Macroeconomics -- Econometric models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/50513 , vital:42206
- Description: Most climate finances available to Sub-Sahara Africa countries tries to assist governmental and non-governmental institutions decarbonise by reducing greenhouse gases or promote conservation of forests through REDD+ programs. On that backdrop, three main general objectives arises for this study; (1) to examine the impact of climate finance on greenhouse gas emissions (2) To find the impact of climate finance on deforestation in Sub-Sahara Africa (3) To determine the major recipient characteristics that attracts more climate finance to Sub-Sahara Africa. The first general objective looked at three greenhouse gas variables; carbon emission, methane and nitrous oxide emission. Data was analysed using system GMM for all countries in Sub-Sahara Africa for the period 2006-2017 based on data availability. The first general objective of the study employed system GMM robust standard errors and triangulates the result by using DOLS and FMOLS for robustness check. The findings show that climate finance is not reducing nitrous oxide, methane and total greenhouse gas emissions into the atmosphere, whereas carbon emission showed mixed results. System GMM results affirmed the existence of EKC, but DOLS and FMOLS results gave a contradictory finding. Based on that, we cannot conclude the existence of EKC for our studies. Energy consumption showed a positive significant impact on carbon, methane and total greenhouse gas for all three models in accordance to prior studies and affirming pollution haven hypothesis, but a mixed result for nitrous oxide. Finally, the findings from governance readiness showed governments in Africa’s unwillingness to reduce carbon but very keen in reducing the other greenhouses gases for all three models. Existence of pollution haven hypothesis shows that more hazardous and dirty investments are moving from developed countries to developing countries with less strict environmental rules like Sub-Sahara Africa. The second and third general objectives of the study employed system-GMM estimation technique to take care of time series variations in the data, as well as capture the unobserved country-specific time-invariant effect. Three and four stages hierarchical regressions are carried out for objectives two and three respectively and a panel quantile regression is employed to test sensitivity of the results for both analysis. The findings for objective two showed that increase in climate climate finance increases deforestation in two models and one model showing a decrease in deforestation, making the result very difficult to interpret and mixed. The study did not also get support for EKC but indicated that forest transition curve is rather U-shaped for all countries in Sub-Sahara Africa and two sub-regional blocks; EAC and CEMAC. Population growth and agricultural land use have been found to be major drivers of deforestation. Most of the governance indicators showed adverse impact on deforestation. The result for objective three indicates that Sub-Sahara African countries with high population growth rate, higher poverty levels, better ease of doing business profile, weaker governance policies, weaker control of corruption, stronger rule of law enforcement, deepened social inequality and better ICT usage have attracted more climate finance. Based on that, we recommend Africa countries to strengthen their practice of rule of law and more stringent rules to prevent or minimize corruption in the system. Climate finance managers should also undertake rigorous monitoring and supervision when funds are extended to reduce misappropriation of funds by recipients.
- Full Text:
- Date Issued: 2020
- Authors: Doku, Isaac
- Date: 2020
- Subjects: Climatic changes -- Economic aspects , Economic development -- Environmental aspects Macroeconomics -- Econometric models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/50513 , vital:42206
- Description: Most climate finances available to Sub-Sahara Africa countries tries to assist governmental and non-governmental institutions decarbonise by reducing greenhouse gases or promote conservation of forests through REDD+ programs. On that backdrop, three main general objectives arises for this study; (1) to examine the impact of climate finance on greenhouse gas emissions (2) To find the impact of climate finance on deforestation in Sub-Sahara Africa (3) To determine the major recipient characteristics that attracts more climate finance to Sub-Sahara Africa. The first general objective looked at three greenhouse gas variables; carbon emission, methane and nitrous oxide emission. Data was analysed using system GMM for all countries in Sub-Sahara Africa for the period 2006-2017 based on data availability. The first general objective of the study employed system GMM robust standard errors and triangulates the result by using DOLS and FMOLS for robustness check. The findings show that climate finance is not reducing nitrous oxide, methane and total greenhouse gas emissions into the atmosphere, whereas carbon emission showed mixed results. System GMM results affirmed the existence of EKC, but DOLS and FMOLS results gave a contradictory finding. Based on that, we cannot conclude the existence of EKC for our studies. Energy consumption showed a positive significant impact on carbon, methane and total greenhouse gas for all three models in accordance to prior studies and affirming pollution haven hypothesis, but a mixed result for nitrous oxide. Finally, the findings from governance readiness showed governments in Africa’s unwillingness to reduce carbon but very keen in reducing the other greenhouses gases for all three models. Existence of pollution haven hypothesis shows that more hazardous and dirty investments are moving from developed countries to developing countries with less strict environmental rules like Sub-Sahara Africa. The second and third general objectives of the study employed system-GMM estimation technique to take care of time series variations in the data, as well as capture the unobserved country-specific time-invariant effect. Three and four stages hierarchical regressions are carried out for objectives two and three respectively and a panel quantile regression is employed to test sensitivity of the results for both analysis. The findings for objective two showed that increase in climate climate finance increases deforestation in two models and one model showing a decrease in deforestation, making the result very difficult to interpret and mixed. The study did not also get support for EKC but indicated that forest transition curve is rather U-shaped for all countries in Sub-Sahara Africa and two sub-regional blocks; EAC and CEMAC. Population growth and agricultural land use have been found to be major drivers of deforestation. Most of the governance indicators showed adverse impact on deforestation. The result for objective three indicates that Sub-Sahara African countries with high population growth rate, higher poverty levels, better ease of doing business profile, weaker governance policies, weaker control of corruption, stronger rule of law enforcement, deepened social inequality and better ICT usage have attracted more climate finance. Based on that, we recommend Africa countries to strengthen their practice of rule of law and more stringent rules to prevent or minimize corruption in the system. Climate finance managers should also undertake rigorous monitoring and supervision when funds are extended to reduce misappropriation of funds by recipients.
- Full Text:
- Date Issued: 2020
Individualism and collectivism as moderators of the relationship between achievement motivation and entrepreneurial interest among undergraduate students at Walter Sisulu University
- Authors: Magadlela, Asanda Sinazo
- Date: 2020
- Subjects: Individualism -- Psychological aspects Collectivism -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/18543 , vital:42607
- Description: The purpose of this study” is “to explore individualism and collectivism” “as moderators of the relationship between entrepreneurial” interest “and achievement motivation”among undergraduate students. The study is focused on analysing the relationship behind the variables and what drives the University students of Walter Sisulu University towards the business development of young people. “Researchers have traditionally associated individualism with high rates of firm creation, arguing that an orientation towards achievement and the pursuit of personal objectives” (dominant aspects of individualist cultures) “are determinants of entrepreneurial activity.” “The current analysis shows that a culture correlates to entrepreneurship”, “but cannot uphold the idea that higher levels of individualism mean higher rates of entrepreneurship.” “Many universities have introduced entrepreneurship education to promote the interest” of undergraduates in “becoming future entrepreneurs. Here, the researcher tries to retrieve the undergraduate’s interest and achievement motivation which influences them to entrepreneurial intentions. Based on” the “literature” review, it identifies various factors that are used in the predictions of entrepreneurial interest. “These factors were” adopted “to explore” student’s interests. “Survey questionnaires were distributed to” two campuses from the University of Walter Sisulu, namely; College street campus (East London) and the Potsdam campus which is the main campus of the University. “A total of” 154 “valid data” was “analysed using multiple regressions. The results show that entrepreneurial” interest “was predicted by achievement” motivation, individualism and collectivism.
- Full Text:
- Date Issued: 2020
- Authors: Magadlela, Asanda Sinazo
- Date: 2020
- Subjects: Individualism -- Psychological aspects Collectivism -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/18543 , vital:42607
- Description: The purpose of this study” is “to explore individualism and collectivism” “as moderators of the relationship between entrepreneurial” interest “and achievement motivation”among undergraduate students. The study is focused on analysing the relationship behind the variables and what drives the University students of Walter Sisulu University towards the business development of young people. “Researchers have traditionally associated individualism with high rates of firm creation, arguing that an orientation towards achievement and the pursuit of personal objectives” (dominant aspects of individualist cultures) “are determinants of entrepreneurial activity.” “The current analysis shows that a culture correlates to entrepreneurship”, “but cannot uphold the idea that higher levels of individualism mean higher rates of entrepreneurship.” “Many universities have introduced entrepreneurship education to promote the interest” of undergraduates in “becoming future entrepreneurs. Here, the researcher tries to retrieve the undergraduate’s interest and achievement motivation which influences them to entrepreneurial intentions. Based on” the “literature” review, it identifies various factors that are used in the predictions of entrepreneurial interest. “These factors were” adopted “to explore” student’s interests. “Survey questionnaires were distributed to” two campuses from the University of Walter Sisulu, namely; College street campus (East London) and the Potsdam campus which is the main campus of the University. “A total of” 154 “valid data” was “analysed using multiple regressions. The results show that entrepreneurial” interest “was predicted by achievement” motivation, individualism and collectivism.
- Full Text:
- Date Issued: 2020
Informal learning in local farming practices by rural women in the Lake Chilwa Basin, Malawi: towards coping and adaptation to climate variability and climate change
- Authors: Mphepo, Gibson Yadunda
- Date: 2020
- Subjects: Women -- Non-formal education - Malawi , Non-formal education -- Malawi , Women -- Malawi -- Social conditions , Crops and climate -- Malawi , Agricultural extension work -- Government policy -- Malawi , Environmental education -- Malawi
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167540 , vital:41490
- Description: Evidence reveals that informal learning is a neglected research area, globally and nationally. Informal learning, like formal and non-formal learning, is context specific. In the case of my study, the context was in local maize cultivation and the associated local farming practices which are also neglected. Research has shown that rural women in Malawi are significant change agents in socio-economic sectors, yet they are heavily affected by inequality. For example, extreme weather events of droughts and floods in the Lake Chilwa Basin, disproportionately affect more women than men because of their traditional gendered roles such as home care. The complexity of the dualistic nature of being change agents and victims of injustices at the same time offers a catalytic opportunity for potentially transformative social learning for transformative adaptation. Against this backdrop, I conducted a study to investigate and expand informal learning processes to contribute to building the resilience of women and other community members in Domasi and Nsanama Extension Planning Areas (EPA) within the Lake Chilwa Basin. Specifically, the study answered the following question: “How do drought and inter-seasonal dry spells influence informal learning processes to enable transformation adaptation among rural women cultivating maize in the Lake Chilwa Basin, Malawi?” To address the question, the first stage was to review local farming practices and the associated informal learning processes in Malawi. I then used third generation Cultural Historical Activity Theory (CHAT) as an overarching theoretical framework to guide the subsequent research processes which were split into three main phases: mirror data collection for expansive learning, formative change laboratory workshops, and data analysis and reflection. CHAT is a theoretical framework that helps us comprehend and analyze the relationship between the human mind (i.e. what people think and feel) and activity (what people do). It is a formative and activist learning theory that posits learning as occurring through collective activities to meet or change a common object (Mukute and Lotz-Sisitka, 2012, p. 345). For Koszalka and Wu, 2001(p. 493), within a CHAT framework, knowledge is socially constructed by individual learners, building on existing historical experiences, within the learners’ context. To construct this knowledge, learners use technology or mediating tools, as Vygotsky (1978) calls them. To collect mirror data, I conducted focus group discussions, observation studies, and document analysis. I also conducted key informant interviews with selected extension workers responsible for the two case study sites. The hub of my research constituted change laboratory workshops to expand learning through four of the seven expansive learning actions, namely questioning, analysis, modeling and testing the model. One of the essential procedures I relied on to expand learning during these change laboratory workshops was identification and analysis of contradictions that were mirrored back to women. The use of contradictions as fertile ground for learning is premised on Engstrom’s arguments that contradictions form a catalyst for learning. Data were analysed using two approaches: layered and power relations. A layered analysis is a step-by-step process of understanding a situation from the lower to a higher level (mature stage). For my research, this meant understanding sequential learning from questioning (session 1 – lower level) to testing the model (session 8 – higher level). The second data analysis approach, power relations, relates to the Women Empowerment in Agriculture Index (WEAI), a measure of the degree of women empowerment, their agency and inclusion in farming (Ruth et al., 2013, p. 3). I used this type of power analysis tool because my research was agriculture based. Both data analysis approaches relied on N-vivo which is a form of computer-based qualitative data management software. The software was ideal for my study which was also mostly qualitative. During phase 1 of data collection, I identified five local farming practices associated with local maize cultivation, a focus of my study. These practices were slash and burn (mphanje); traditional insect pest control measures; soil fertility enhancement techniques through kuojeka (crop residue incorporation) and livestock manure; traditional weather forecasts; and multiple cropping (mixed and sequential cropping). Among these, the most preferred by the women I interacted with were kuojeka, livestock manure and mixed cropping. I discovered that these local farming practices are informally learned mainly through word of mouth, observation, trials, women-dominated social networks and drama. I also discovered that some of these informal learning pathways are catalyzed by drought and dry spells. For example, during the 1949 and 2002 drought periods, women reported that they had learned new types of coping strategies such as the use of sawdust and banana root flour in place of maize flour to prepare nsima, a staple food in Malawi. During phase 2, change laboratory workshops, I identified 19 contradictions associated with local farming practices, most of which were related to the Government of Malawi bias towards modern farming practices such as hybrids. Other contradictions were related to traditional structures and norms and religion and traditional beliefs. Solutions were suggested for each of the contradictions. Some of these solutions were tested for their workability. These included setting up diversity blocks (demonstration plots) for local maize cultivation under irrigation and engagement of the youth through WhatsApp groups for the first time at the study sites. The results of the tests show that there is potential to transform local farming practices at the study sites and build social resilience against drought and dry spells. For example, from a local maize demonstration plot in Nsanama Extension Planning Area (EPA), farmers learned that kafula local maize is fast maturing and therefore cushions them against hunger as they wait for the main harvest in later months. Eighty-eight households shared local maize seed harvested from the demonstration gardens for upscaling. The Head of Nsanama EPA had also set up another demonstration garden in 2018-2019 growing season consisting of kafula at Nsanama EPA Headquarters for further informal learning purposes. This research has contributed new knowledge to the existing knowledge base about local farming practices and informal learning. These contributions are in the form of methods I used as well as results obtained. Among the key highlights of my contribution to the knowledge base is the development of scenarios as double stimulation tools for the emerging local farming activity system which emanates from the new model solutions resulting from change laboratory workshops. To the best of my knowledge, this was the first time rural communities were engaged in scenario development in Malawi. The first scenarios of this type were developed in 2010 for the Malawi State of Environment and Outlook Report and the process involved middle to senior managers of various institutions in Malawi. Through historical analysis, my research identified local crops that existed in the past but which are currently non-existent or rare. My study also identified unique local farming practices that even puzzled professionals, including the use of ripe banana peels of makumbuka and sukari to eradicate nansongole grass and native bamboos respectively. Both plant species are considered a nuisance in that they colonize land for cultivation. A breakthrough for radical transformation of local farming practices via informal learning requires development and review of relevant policies in Malawi. Such a process requires evidence. This research has provided background information for this process. For those policies already developed, this research has provided information that can help guide implementation of the generalized list of activities outlined in implementation plans of the respective policies.
- Full Text:
- Date Issued: 2020
- Authors: Mphepo, Gibson Yadunda
- Date: 2020
- Subjects: Women -- Non-formal education - Malawi , Non-formal education -- Malawi , Women -- Malawi -- Social conditions , Crops and climate -- Malawi , Agricultural extension work -- Government policy -- Malawi , Environmental education -- Malawi
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167540 , vital:41490
- Description: Evidence reveals that informal learning is a neglected research area, globally and nationally. Informal learning, like formal and non-formal learning, is context specific. In the case of my study, the context was in local maize cultivation and the associated local farming practices which are also neglected. Research has shown that rural women in Malawi are significant change agents in socio-economic sectors, yet they are heavily affected by inequality. For example, extreme weather events of droughts and floods in the Lake Chilwa Basin, disproportionately affect more women than men because of their traditional gendered roles such as home care. The complexity of the dualistic nature of being change agents and victims of injustices at the same time offers a catalytic opportunity for potentially transformative social learning for transformative adaptation. Against this backdrop, I conducted a study to investigate and expand informal learning processes to contribute to building the resilience of women and other community members in Domasi and Nsanama Extension Planning Areas (EPA) within the Lake Chilwa Basin. Specifically, the study answered the following question: “How do drought and inter-seasonal dry spells influence informal learning processes to enable transformation adaptation among rural women cultivating maize in the Lake Chilwa Basin, Malawi?” To address the question, the first stage was to review local farming practices and the associated informal learning processes in Malawi. I then used third generation Cultural Historical Activity Theory (CHAT) as an overarching theoretical framework to guide the subsequent research processes which were split into three main phases: mirror data collection for expansive learning, formative change laboratory workshops, and data analysis and reflection. CHAT is a theoretical framework that helps us comprehend and analyze the relationship between the human mind (i.e. what people think and feel) and activity (what people do). It is a formative and activist learning theory that posits learning as occurring through collective activities to meet or change a common object (Mukute and Lotz-Sisitka, 2012, p. 345). For Koszalka and Wu, 2001(p. 493), within a CHAT framework, knowledge is socially constructed by individual learners, building on existing historical experiences, within the learners’ context. To construct this knowledge, learners use technology or mediating tools, as Vygotsky (1978) calls them. To collect mirror data, I conducted focus group discussions, observation studies, and document analysis. I also conducted key informant interviews with selected extension workers responsible for the two case study sites. The hub of my research constituted change laboratory workshops to expand learning through four of the seven expansive learning actions, namely questioning, analysis, modeling and testing the model. One of the essential procedures I relied on to expand learning during these change laboratory workshops was identification and analysis of contradictions that were mirrored back to women. The use of contradictions as fertile ground for learning is premised on Engstrom’s arguments that contradictions form a catalyst for learning. Data were analysed using two approaches: layered and power relations. A layered analysis is a step-by-step process of understanding a situation from the lower to a higher level (mature stage). For my research, this meant understanding sequential learning from questioning (session 1 – lower level) to testing the model (session 8 – higher level). The second data analysis approach, power relations, relates to the Women Empowerment in Agriculture Index (WEAI), a measure of the degree of women empowerment, their agency and inclusion in farming (Ruth et al., 2013, p. 3). I used this type of power analysis tool because my research was agriculture based. Both data analysis approaches relied on N-vivo which is a form of computer-based qualitative data management software. The software was ideal for my study which was also mostly qualitative. During phase 1 of data collection, I identified five local farming practices associated with local maize cultivation, a focus of my study. These practices were slash and burn (mphanje); traditional insect pest control measures; soil fertility enhancement techniques through kuojeka (crop residue incorporation) and livestock manure; traditional weather forecasts; and multiple cropping (mixed and sequential cropping). Among these, the most preferred by the women I interacted with were kuojeka, livestock manure and mixed cropping. I discovered that these local farming practices are informally learned mainly through word of mouth, observation, trials, women-dominated social networks and drama. I also discovered that some of these informal learning pathways are catalyzed by drought and dry spells. For example, during the 1949 and 2002 drought periods, women reported that they had learned new types of coping strategies such as the use of sawdust and banana root flour in place of maize flour to prepare nsima, a staple food in Malawi. During phase 2, change laboratory workshops, I identified 19 contradictions associated with local farming practices, most of which were related to the Government of Malawi bias towards modern farming practices such as hybrids. Other contradictions were related to traditional structures and norms and religion and traditional beliefs. Solutions were suggested for each of the contradictions. Some of these solutions were tested for their workability. These included setting up diversity blocks (demonstration plots) for local maize cultivation under irrigation and engagement of the youth through WhatsApp groups for the first time at the study sites. The results of the tests show that there is potential to transform local farming practices at the study sites and build social resilience against drought and dry spells. For example, from a local maize demonstration plot in Nsanama Extension Planning Area (EPA), farmers learned that kafula local maize is fast maturing and therefore cushions them against hunger as they wait for the main harvest in later months. Eighty-eight households shared local maize seed harvested from the demonstration gardens for upscaling. The Head of Nsanama EPA had also set up another demonstration garden in 2018-2019 growing season consisting of kafula at Nsanama EPA Headquarters for further informal learning purposes. This research has contributed new knowledge to the existing knowledge base about local farming practices and informal learning. These contributions are in the form of methods I used as well as results obtained. Among the key highlights of my contribution to the knowledge base is the development of scenarios as double stimulation tools for the emerging local farming activity system which emanates from the new model solutions resulting from change laboratory workshops. To the best of my knowledge, this was the first time rural communities were engaged in scenario development in Malawi. The first scenarios of this type were developed in 2010 for the Malawi State of Environment and Outlook Report and the process involved middle to senior managers of various institutions in Malawi. Through historical analysis, my research identified local crops that existed in the past but which are currently non-existent or rare. My study also identified unique local farming practices that even puzzled professionals, including the use of ripe banana peels of makumbuka and sukari to eradicate nansongole grass and native bamboos respectively. Both plant species are considered a nuisance in that they colonize land for cultivation. A breakthrough for radical transformation of local farming practices via informal learning requires development and review of relevant policies in Malawi. Such a process requires evidence. This research has provided background information for this process. For those policies already developed, this research has provided information that can help guide implementation of the generalized list of activities outlined in implementation plans of the respective policies.
- Full Text:
- Date Issued: 2020
Information needs and information-seeking behaviour of practising medical doctors at Katutura and Windhoek central state hospitals in Namibia
- Authors: Matsveru, David
- Date: 2020
- Subjects: Information behavior Information resources
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/17976 , vital:42000
- Description: This study investigated the information needs and information-seeking behaviour of practising medical doctors at Katutura and Windhoek Central hospitals in Namibia. Anchored on Wilson’s (1996) model of information-seeking behaviour, the purpose of the study was to establish the information required by practising medical doctors to carry out their work, how they seek information, the information sources and resources they use, and the factors that affect them as they do so. Understanding users’ information needs and the way information is disseminated in hospitals is necessary in developing an effective information provision system and ensuring the quality of information services in the hospitals. A mixed-methods research approach was used to meet the objectives of the study. Questionnaires were administered on 140 practising medical doctors at Katutura and Windhoek Central state hospitals, while fifteen doctors were interviewed telephonically, using a semi-structured interview guide. IBM SPSS (Version 25) was used to analyse quantitative data from the questionnaires, while content analysis was used to analyse qualitative data from the interviews. The findings of this research are that practising medical doctors need information mainly for improving clinical decision-making, keeping up-to-date, improving professional knowledge, and continuing education. The study also revealed that medical doctors use a variety of information sources and resources. However, the degree to which information sources are xiii used depends on the clinical context (outpatients, wards and casualty/emergency). Some contextual factors (organisational context, socio-cultural context, and information sources) can either support or hinder doctors in seeking the information they need. The patient is one of the primary information sources for medical doctors. However, language problems are a significant challenge in communicating with patients or patients’ relatives. Lack of patients’ understanding of medical terms and unavailability of properly run libraries in hospitals are some of the factors that affect doctors’ information-seeking behaviour. Participants recommended health education for patients, training of medical doctors on the use of the Internet and ICT, provision of properly run hospital libraries, and improved communication with other international hospitals as some of the ways to improve health information sources and services. Three related models were drawn from the study’s findings, based on Wilson’s (1996) model and literature, namely, the doctors’ decision-making model (DDmM), the clinical context information sources model (CCISM), and the model of information needs and information-seeking behaviour of medical doctors (MINISBMD). The thesis concludes with practical recommendations to enhance the provision of information at Katutura and Windhoek Central hospitals and suggestions for further research.
- Full Text:
- Date Issued: 2020
- Authors: Matsveru, David
- Date: 2020
- Subjects: Information behavior Information resources
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/17976 , vital:42000
- Description: This study investigated the information needs and information-seeking behaviour of practising medical doctors at Katutura and Windhoek Central hospitals in Namibia. Anchored on Wilson’s (1996) model of information-seeking behaviour, the purpose of the study was to establish the information required by practising medical doctors to carry out their work, how they seek information, the information sources and resources they use, and the factors that affect them as they do so. Understanding users’ information needs and the way information is disseminated in hospitals is necessary in developing an effective information provision system and ensuring the quality of information services in the hospitals. A mixed-methods research approach was used to meet the objectives of the study. Questionnaires were administered on 140 practising medical doctors at Katutura and Windhoek Central state hospitals, while fifteen doctors were interviewed telephonically, using a semi-structured interview guide. IBM SPSS (Version 25) was used to analyse quantitative data from the questionnaires, while content analysis was used to analyse qualitative data from the interviews. The findings of this research are that practising medical doctors need information mainly for improving clinical decision-making, keeping up-to-date, improving professional knowledge, and continuing education. The study also revealed that medical doctors use a variety of information sources and resources. However, the degree to which information sources are xiii used depends on the clinical context (outpatients, wards and casualty/emergency). Some contextual factors (organisational context, socio-cultural context, and information sources) can either support or hinder doctors in seeking the information they need. The patient is one of the primary information sources for medical doctors. However, language problems are a significant challenge in communicating with patients or patients’ relatives. Lack of patients’ understanding of medical terms and unavailability of properly run libraries in hospitals are some of the factors that affect doctors’ information-seeking behaviour. Participants recommended health education for patients, training of medical doctors on the use of the Internet and ICT, provision of properly run hospital libraries, and improved communication with other international hospitals as some of the ways to improve health information sources and services. Three related models were drawn from the study’s findings, based on Wilson’s (1996) model and literature, namely, the doctors’ decision-making model (DDmM), the clinical context information sources model (CCISM), and the model of information needs and information-seeking behaviour of medical doctors (MINISBMD). The thesis concludes with practical recommendations to enhance the provision of information at Katutura and Windhoek Central hospitals and suggestions for further research.
- Full Text:
- Date Issued: 2020
Invasion status and impact potential of Florida bass Micropterus floridanus in South Africa
- Authors: Khosa, Dumisani
- Date: 2020
- Subjects: Micropterus floridanus , Florida largemouth bass -- South Africa , Black bass -- South Africa , Micropterus floridanus -- South Africa -- Habitat , Florida largemouth bass -- South Africa -- Habitat , Black bass -- South Africa -- Habitat , Introduced fishes -- Environmental aspects -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/165733 , vital:41276
- Description: In South Africa, the introduction of alien fishes was largely driven by the development of recreational fishing opportunities. Government-backed programmes resulted in the introduction of four Black Bass species: Micropterus salmoides, Micropterus dolomieu, Micropterus punctulatus and Micropterus floridanus. These species are regarded as the primary threat to native biota and there is an urgent need to assess their spread and impacts. This thesis focuses on: assessing the current distribution of all four Black Basses; using genetic techniques to establish the extent of hybridisation between M. salmoides and M. floridanus, and using functional responses to assess the impact potential of M. salmoides and M. floridanus under the context dependence of temperatures and habitat complexity. Maximum entropy modelling of habitat suitability for Black Bass highlighted that M. salmoides had broad climatic suitability across South Africa, while suitability for M. dolomieu and M. punctulatus was restricted to the Cape Fold Ecoregion. An extensive area-based invasion debt was observed for all Micropterus spp. To better understand the dynamics of hybridisation between M. salmoides and M. floridanus, 38 species-diagnostic single nucleotide polymorphism was used to screen Black Bass populations from the Breede River and Kowie River catchments. Micropterus salmoides alleles were more prevalent than M. floridanus in both the Breede River catchments (69.1% and 30.9%, respectively) and Kowie River catchments (63.3% and 36.7%, respectively). However, isolated populations found in dams (reservoirs) remained free from hybridisation. To compare resource utilisation (i.e. per capita effects) between M. salmoides and M. floridanus, two experimental chapters were designed. Chapter 4 focuses on how temperature mitigates per capita effects between the two Black Basses. There was a significant decrease in per capita effects for M. salmoides with increasing temperatures, while the converse was true for M. floridanus. Chapter 5 gives an account of the influence of habitat complexity on per capita effects. The results showed that habitat complexity did mitigate per capita effects, specifically on M. floridanus, which showed a significant drop in per capita effects; however, no significant difference was recorded for M. salmoides. In the two experimental chapters, M. floridanus exhibited a superior per capita effect compared to M. salmoides, implying higher predation impact on native biota.
- Full Text:
- Date Issued: 2020
- Authors: Khosa, Dumisani
- Date: 2020
- Subjects: Micropterus floridanus , Florida largemouth bass -- South Africa , Black bass -- South Africa , Micropterus floridanus -- South Africa -- Habitat , Florida largemouth bass -- South Africa -- Habitat , Black bass -- South Africa -- Habitat , Introduced fishes -- Environmental aspects -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/165733 , vital:41276
- Description: In South Africa, the introduction of alien fishes was largely driven by the development of recreational fishing opportunities. Government-backed programmes resulted in the introduction of four Black Bass species: Micropterus salmoides, Micropterus dolomieu, Micropterus punctulatus and Micropterus floridanus. These species are regarded as the primary threat to native biota and there is an urgent need to assess their spread and impacts. This thesis focuses on: assessing the current distribution of all four Black Basses; using genetic techniques to establish the extent of hybridisation between M. salmoides and M. floridanus, and using functional responses to assess the impact potential of M. salmoides and M. floridanus under the context dependence of temperatures and habitat complexity. Maximum entropy modelling of habitat suitability for Black Bass highlighted that M. salmoides had broad climatic suitability across South Africa, while suitability for M. dolomieu and M. punctulatus was restricted to the Cape Fold Ecoregion. An extensive area-based invasion debt was observed for all Micropterus spp. To better understand the dynamics of hybridisation between M. salmoides and M. floridanus, 38 species-diagnostic single nucleotide polymorphism was used to screen Black Bass populations from the Breede River and Kowie River catchments. Micropterus salmoides alleles were more prevalent than M. floridanus in both the Breede River catchments (69.1% and 30.9%, respectively) and Kowie River catchments (63.3% and 36.7%, respectively). However, isolated populations found in dams (reservoirs) remained free from hybridisation. To compare resource utilisation (i.e. per capita effects) between M. salmoides and M. floridanus, two experimental chapters were designed. Chapter 4 focuses on how temperature mitigates per capita effects between the two Black Basses. There was a significant decrease in per capita effects for M. salmoides with increasing temperatures, while the converse was true for M. floridanus. Chapter 5 gives an account of the influence of habitat complexity on per capita effects. The results showed that habitat complexity did mitigate per capita effects, specifically on M. floridanus, which showed a significant drop in per capita effects; however, no significant difference was recorded for M. salmoides. In the two experimental chapters, M. floridanus exhibited a superior per capita effect compared to M. salmoides, implying higher predation impact on native biota.
- Full Text:
- Date Issued: 2020
Investigating the fitness of sea turtles nesting in South Africa
- Le Gouvello du Timat, Diane Z M
- Authors: Le Gouvello du Timat, Diane Z M
- Date: 2020
- Subjects: Sea turtles -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/48445 , vital:40877
- Description: The South African rookeries of the South Western Indian Ocean (SWIO) loggerhead and leatherback regional management units have been continuously monitored for more than 5 decades, representing one of the longest-running sea turtle beach protection and monitoring programmes in the world. Although such conservation has been successful in protecting adults on land when they come to nest, it might not be enough to ensure population recovery if survival is not ensured across all life stages. Sea turtles are particularly vulnerable to direct threats and changing environmental conditions because they are long-lived, slow maturing, and have low survival rates at early life stages, making them conservation-dependent. These characteristics also render them difficult to conserve as a consequence of their wide geographic distributions, spanning multiple jurisdictions and legislative systems with different conservation targets, and a complex life cycle with changes in habitats and diets at different life stages. Sea turtle populations have been severely depleted as a result of historical over-exploitation and current threats including fisheries bycatch, direct harvest, habitat loss, pollution and pathogens, and climate change. In many cases however, population declines have been reversed by a variety of effective conservation measures such as beach protection programs, and marine protected areas, enabling successful population recovery around the world. Despite protection and apparent increase in abundance, indirect pressures can still affect turtle populations. Therefore, it is fundamental to evaluate the effectiveness of conservation measures (using fitness traits such as female and hatchling sizes) and examine underlying trends. The aim of this thesis was thus to evaluate the fitness of loggerhead and leatherback sea turtles nesting in South Africa. Long-term female size trends over time were evaluated and the populations were split between first-time nesters and experienced nesters. As sea turtle reproductive output (clutch size only) is correlated with female size and evidence is showing that in some populations individual female size is decreasing, the effects of maternal body size on reproductive output and hatchling fitness were investigated for both species. Crawling and swimming speeds were used as proxies of hatchling fitness, because these two traits positively influence their survival. An oceanic model was further used in combination with a particle tracking framework to estimate, for the first time, post-hatchling dispersal of loggerhead and leatherback turtles in the SWIO. I investigated whether the trend in female size for loggerhead turtles nesting in South Africa is a result of their foraging strategy to determine if there is a foraging dichotomy (neritic and oceanic). Despite an apparent increasing population, a significant 3.7 and 3.6 cm decrease in the size of both recruit and remingrant female loggerhead turtles, but a stable mean size of leatherbacks for both age groups was observed. I hypothesise that these contradictory effects are attributable to the very distinct foraging ecologies of the two turtle species and speculate that these variations in carapace length may be driven by environmental change. The reproductive strategy of both loggerhead and leatherback turtles nesting in South Africa supports the optimal egg size theory with larger turtles producing larger clutches but not larger eggs. Egg size was thus constant irrespective of maternal length. Hatchlings with longer carapaces and flippers had higher swimming speed, suggesting that larger hatchlings are fitter (potentially higher survival) than smaller ones by spending less time in high predation risk areas (i.e. beach and nearshore). The model revealed that dispersal trajectories of both loggerhead and leatherback sea turtle hatchlings were very similar and simulations indicated that initial active swimming (frenzy) as well as variability in oceanic conditions strongly influenced dispersal of virtual hatchlings. The trends observed in this study emphasize the importance of long-term monitoring, examining not only abundance but also individual size, to understand population dynamics, support recovery planning and prioritize future conservation practices. Furthermore, the findings of this study have important implications for overall population growth if smaller hatchlings of lower fitness are produced as a result of climate change and thus have decreased dispersal abilities and lower likelihood of survival.
- Full Text:
- Date Issued: 2020
- Authors: Le Gouvello du Timat, Diane Z M
- Date: 2020
- Subjects: Sea turtles -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/48445 , vital:40877
- Description: The South African rookeries of the South Western Indian Ocean (SWIO) loggerhead and leatherback regional management units have been continuously monitored for more than 5 decades, representing one of the longest-running sea turtle beach protection and monitoring programmes in the world. Although such conservation has been successful in protecting adults on land when they come to nest, it might not be enough to ensure population recovery if survival is not ensured across all life stages. Sea turtles are particularly vulnerable to direct threats and changing environmental conditions because they are long-lived, slow maturing, and have low survival rates at early life stages, making them conservation-dependent. These characteristics also render them difficult to conserve as a consequence of their wide geographic distributions, spanning multiple jurisdictions and legislative systems with different conservation targets, and a complex life cycle with changes in habitats and diets at different life stages. Sea turtle populations have been severely depleted as a result of historical over-exploitation and current threats including fisheries bycatch, direct harvest, habitat loss, pollution and pathogens, and climate change. In many cases however, population declines have been reversed by a variety of effective conservation measures such as beach protection programs, and marine protected areas, enabling successful population recovery around the world. Despite protection and apparent increase in abundance, indirect pressures can still affect turtle populations. Therefore, it is fundamental to evaluate the effectiveness of conservation measures (using fitness traits such as female and hatchling sizes) and examine underlying trends. The aim of this thesis was thus to evaluate the fitness of loggerhead and leatherback sea turtles nesting in South Africa. Long-term female size trends over time were evaluated and the populations were split between first-time nesters and experienced nesters. As sea turtle reproductive output (clutch size only) is correlated with female size and evidence is showing that in some populations individual female size is decreasing, the effects of maternal body size on reproductive output and hatchling fitness were investigated for both species. Crawling and swimming speeds were used as proxies of hatchling fitness, because these two traits positively influence their survival. An oceanic model was further used in combination with a particle tracking framework to estimate, for the first time, post-hatchling dispersal of loggerhead and leatherback turtles in the SWIO. I investigated whether the trend in female size for loggerhead turtles nesting in South Africa is a result of their foraging strategy to determine if there is a foraging dichotomy (neritic and oceanic). Despite an apparent increasing population, a significant 3.7 and 3.6 cm decrease in the size of both recruit and remingrant female loggerhead turtles, but a stable mean size of leatherbacks for both age groups was observed. I hypothesise that these contradictory effects are attributable to the very distinct foraging ecologies of the two turtle species and speculate that these variations in carapace length may be driven by environmental change. The reproductive strategy of both loggerhead and leatherback turtles nesting in South Africa supports the optimal egg size theory with larger turtles producing larger clutches but not larger eggs. Egg size was thus constant irrespective of maternal length. Hatchlings with longer carapaces and flippers had higher swimming speed, suggesting that larger hatchlings are fitter (potentially higher survival) than smaller ones by spending less time in high predation risk areas (i.e. beach and nearshore). The model revealed that dispersal trajectories of both loggerhead and leatherback sea turtle hatchlings were very similar and simulations indicated that initial active swimming (frenzy) as well as variability in oceanic conditions strongly influenced dispersal of virtual hatchlings. The trends observed in this study emphasize the importance of long-term monitoring, examining not only abundance but also individual size, to understand population dynamics, support recovery planning and prioritize future conservation practices. Furthermore, the findings of this study have important implications for overall population growth if smaller hatchlings of lower fitness are produced as a result of climate change and thus have decreased dispersal abilities and lower likelihood of survival.
- Full Text:
- Date Issued: 2020
Investigation of potential induced degradation as a performance limiting defect in photovoltaic modules
- Authors: Kwembur, Isaac Morko
- Date: 2020
- Subjects: Photovoltaic cells
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/48423 , vital:40875
- Description: Potential Induced Degradation (PID) impacts negatively on photovoltaic (PV) module durability because it significantly affects the output of PV modules and systems. Unless detected at infancy, PID progression can be catastrophic. This study involved systematic PID stressing of PV modules using a custom-built environmental chamber that can achieve suitable environmental conditions, viz., of the 35 °C ± 1 °C and relative humidity of 75 % ± 5 %. The first part of this work was to induce PID using three approaches: climate chamber testing, inducing PID using a conductive aluminium plate on the surface of the module without touching the frame and a localised PID induction on one cell in a module. The second part is to detect induced PID using Electroluminescence (EL) images taken at current corresponding to 10% Isc, EL histograms analysis and Voc ratio taken at 1000 W/m2 to 200 W/m2 . The third part is to study module regeneration after PID shunting degradation in two ways, viz., forced reverse polarization and natural recovery. The PID detection tools used in this work are well known module characterization techniques such as EL imaging, Infrared imaging, and light and dark current-voltage measurements. These characterisation tools are used in combination to detect defects such as optical losses, cracks, breakage, electric circuit degradation and PID. Under normal testing PID was detected and in some cases, modules were able to recover, while for advanced stage PID regeneration or PID reversal was difficult. This thesis focuses on PID detection at infancy using three approaches; EL imaging at current corresponding to 10% of Isc. Light and dark current – voltage measurements (L-IV & D-IV) and open circuit voltage (Voc) ratios at low irradiance. The early detection procedures are essential in reversing the degradation caused by PID which is reversible. The time taken to reverse the PID degradation will depend on the extent of the degradation. If detected early, it will take a short period of time to completely reverse lost power. Infrared thermography is a non-contact characteristic tool that can be deployed in large scale plants using drones to detect the presence of PID in PV plants. Module performance and device parameters extracted from the L-IV curves on a module before and after PID stress, such as Pmpp, Voc, Isc Fill Factor (FF), shunt resistance (Rsh) and series resistance (Rs) and ideality (n) are sensitive to PID shunting. Voc and Rsh drop significantly with the onset of PID, while Rs increases. The decrease in Voc and Rsh is due to heavy shunting on the module resulting in increased carrier recombination, while the increase in Rs is due to increased shunting paths leading to decreased photocurrent. When substantial degradation on a module occurs Pmpp, FF and n will drop and at very advanced stage of PID degradation Isc may drop excessively.
- Full Text:
- Date Issued: 2020
- Authors: Kwembur, Isaac Morko
- Date: 2020
- Subjects: Photovoltaic cells
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/48423 , vital:40875
- Description: Potential Induced Degradation (PID) impacts negatively on photovoltaic (PV) module durability because it significantly affects the output of PV modules and systems. Unless detected at infancy, PID progression can be catastrophic. This study involved systematic PID stressing of PV modules using a custom-built environmental chamber that can achieve suitable environmental conditions, viz., of the 35 °C ± 1 °C and relative humidity of 75 % ± 5 %. The first part of this work was to induce PID using three approaches: climate chamber testing, inducing PID using a conductive aluminium plate on the surface of the module without touching the frame and a localised PID induction on one cell in a module. The second part is to detect induced PID using Electroluminescence (EL) images taken at current corresponding to 10% Isc, EL histograms analysis and Voc ratio taken at 1000 W/m2 to 200 W/m2 . The third part is to study module regeneration after PID shunting degradation in two ways, viz., forced reverse polarization and natural recovery. The PID detection tools used in this work are well known module characterization techniques such as EL imaging, Infrared imaging, and light and dark current-voltage measurements. These characterisation tools are used in combination to detect defects such as optical losses, cracks, breakage, electric circuit degradation and PID. Under normal testing PID was detected and in some cases, modules were able to recover, while for advanced stage PID regeneration or PID reversal was difficult. This thesis focuses on PID detection at infancy using three approaches; EL imaging at current corresponding to 10% of Isc. Light and dark current – voltage measurements (L-IV & D-IV) and open circuit voltage (Voc) ratios at low irradiance. The early detection procedures are essential in reversing the degradation caused by PID which is reversible. The time taken to reverse the PID degradation will depend on the extent of the degradation. If detected early, it will take a short period of time to completely reverse lost power. Infrared thermography is a non-contact characteristic tool that can be deployed in large scale plants using drones to detect the presence of PID in PV plants. Module performance and device parameters extracted from the L-IV curves on a module before and after PID stress, such as Pmpp, Voc, Isc Fill Factor (FF), shunt resistance (Rsh) and series resistance (Rs) and ideality (n) are sensitive to PID shunting. Voc and Rsh drop significantly with the onset of PID, while Rs increases. The decrease in Voc and Rsh is due to heavy shunting on the module resulting in increased carrier recombination, while the increase in Rs is due to increased shunting paths leading to decreased photocurrent. When substantial degradation on a module occurs Pmpp, FF and n will drop and at very advanced stage of PID degradation Isc may drop excessively.
- Full Text:
- Date Issued: 2020
Investigations into biological control options for Lycium ferocissimum Miers, African Boxthorn (Solanaceae) for Australia
- Authors: Mauda, Evans Vusani
- Date: 2020
- Subjects: Lycium ferocissimum , Solanaceae -- Biological control -- Australia , Weeds -- Control -- Australia , Invasive plants -- Biological control -- Australia , Insects as biological pest control agents -- Australia , Insect-plant relationships
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167142 , vital:41441
- Description: Lycium ferocissimum Miers (Solanaceae) (African boxthorn or boxthorn) is a shrub native to South Africa,and has become naturalised and invasive in Australia and New Zealand. The plant is listed on the Noxious Weed List for Australian States and territories. Although other control methods are available, biological control presents a potentially sustainable intervention for reducing populations of this weed in Australia. In South Africa, the plant has been recorded from two allopatric populations, one in the Eastern Cape Province, the other in the Western Cape Provinces, however, there taxonomic and morphological uncertainties are reported in the literature. Therefore, before native range surveys for potential biological control agents could be considered, the taxonomic uncertainty needed to be resolved. The two geographically distinct areas, as well as the Australia population were sampled to assess morphological and genetic variation. All samples collected in Australia were confirmed as L.ferocissimum, with no evidence of hybridisation with any other Lycium species. Nuclear and chloroplast genetic diversity within L.ferocissimum across South Africa was high, and Australia was low, with no evidence of genetic seperation. One ehaplotypes found across Australia was found at only two sites in South Africa, both in the Western Cape, suggesting that the Australian lineage may have originated from this region. Ten samples from South Africa, putatively identified in the field as L.ferocissimum, were genetically characterised as different (unidentified) Lycium species. The majority of plants sampled were confirmed as L.ferocissimum, sharing a common haplotype (haplotype 5) with sampled specimens from Australia. Morphological analyses across different Lycium species in South Africa did not identify any leaf or floral characteristics unique to L.ferocissimum, and thus morphological identification in the native range remains problematic. Surveys for phytophagous in sects on L.ferocissimum were carried out regularly over a two-year period in the two regions. The number of insect species found in the Eastern Cape Province (55) was higher than in the Western Cape Province (41), but insect diversity based on Shannon indices was highest in the Western Cape Province. Indicator species analysis revealed eight insect herbivore species driving the differences in the herbivore communities between the two provinces. Based on insect distribution, abundance, feeding preference and available literature, three species were prioritised as potential biological control agents. These include the leaf-chewing beetles, Cassida distinguenda Spaeth (Chrysomelidae) and Cleta eckloni Mulsant (Coccinellidae), and the leaf-mining weevil, Neoplatygaster serietuberculata Gyllenhal (Curculionidae). Native range studies such as this are perhaps the most technically difficult and logistically time-consuming part of the biological control programme. Yet, the entire outcome of a programme depends on the suite of potential agents feeding on the weed. The information gained during this stage significantly contributed to the prioritization of agents for further host-range testing and possible release. Here we showed how molecular and genetic characterisations of the target weed can be us ed to accurately define the identity and phylogeny of the target species. In addition, the study also highlighted the importance of considering plant morphology and how phenotypic plasticity may influence infield plant identifications while conducting native range surveys. By gaining further information during long-term and wide spread native range surveys we were not just able to provide a list of herbivorous insect fauna and fungi associated with the plant, but were able to prioritise the phytophagous species that held the most potential as biological control agents.
- Full Text:
- Date Issued: 2020
- Authors: Mauda, Evans Vusani
- Date: 2020
- Subjects: Lycium ferocissimum , Solanaceae -- Biological control -- Australia , Weeds -- Control -- Australia , Invasive plants -- Biological control -- Australia , Insects as biological pest control agents -- Australia , Insect-plant relationships
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167142 , vital:41441
- Description: Lycium ferocissimum Miers (Solanaceae) (African boxthorn or boxthorn) is a shrub native to South Africa,and has become naturalised and invasive in Australia and New Zealand. The plant is listed on the Noxious Weed List for Australian States and territories. Although other control methods are available, biological control presents a potentially sustainable intervention for reducing populations of this weed in Australia. In South Africa, the plant has been recorded from two allopatric populations, one in the Eastern Cape Province, the other in the Western Cape Provinces, however, there taxonomic and morphological uncertainties are reported in the literature. Therefore, before native range surveys for potential biological control agents could be considered, the taxonomic uncertainty needed to be resolved. The two geographically distinct areas, as well as the Australia population were sampled to assess morphological and genetic variation. All samples collected in Australia were confirmed as L.ferocissimum, with no evidence of hybridisation with any other Lycium species. Nuclear and chloroplast genetic diversity within L.ferocissimum across South Africa was high, and Australia was low, with no evidence of genetic seperation. One ehaplotypes found across Australia was found at only two sites in South Africa, both in the Western Cape, suggesting that the Australian lineage may have originated from this region. Ten samples from South Africa, putatively identified in the field as L.ferocissimum, were genetically characterised as different (unidentified) Lycium species. The majority of plants sampled were confirmed as L.ferocissimum, sharing a common haplotype (haplotype 5) with sampled specimens from Australia. Morphological analyses across different Lycium species in South Africa did not identify any leaf or floral characteristics unique to L.ferocissimum, and thus morphological identification in the native range remains problematic. Surveys for phytophagous in sects on L.ferocissimum were carried out regularly over a two-year period in the two regions. The number of insect species found in the Eastern Cape Province (55) was higher than in the Western Cape Province (41), but insect diversity based on Shannon indices was highest in the Western Cape Province. Indicator species analysis revealed eight insect herbivore species driving the differences in the herbivore communities between the two provinces. Based on insect distribution, abundance, feeding preference and available literature, three species were prioritised as potential biological control agents. These include the leaf-chewing beetles, Cassida distinguenda Spaeth (Chrysomelidae) and Cleta eckloni Mulsant (Coccinellidae), and the leaf-mining weevil, Neoplatygaster serietuberculata Gyllenhal (Curculionidae). Native range studies such as this are perhaps the most technically difficult and logistically time-consuming part of the biological control programme. Yet, the entire outcome of a programme depends on the suite of potential agents feeding on the weed. The information gained during this stage significantly contributed to the prioritization of agents for further host-range testing and possible release. Here we showed how molecular and genetic characterisations of the target weed can be us ed to accurately define the identity and phylogeny of the target species. In addition, the study also highlighted the importance of considering plant morphology and how phenotypic plasticity may influence infield plant identifications while conducting native range surveys. By gaining further information during long-term and wide spread native range surveys we were not just able to provide a list of herbivorous insect fauna and fungi associated with the plant, but were able to prioritise the phytophagous species that held the most potential as biological control agents.
- Full Text:
- Date Issued: 2020
Journeying home, exile and transnationalism in Noni Jabavu and Sisonke Msimang’s memoirs
- Authors: Masola, Athambile
- Date: 2020
- Subjects: Home in literature , Exile (Punishment) in literature , Women authors, Black -- South Africa -- History and criticism , Jabavu, Noni -- Criticism and interpretation , Msimang, Sisonke -- Criticism and interpretation
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/166529 , vital:41376
- Description: This thesis examines the memoirs of two South Africa female writers: Noni Jabavu and Sisonke Msimang. In analysing their memoirs, this thesis sets out to contribute to the scholarship which centres the voices of Black women writers. It explores how both writers interrogate the concepts of home, exile and transnationalism. My focus is on the ways in which the writers theorise questions of belonging, and the extent to which their writing provides the opportunity to give voice to the complex nature of belonging. I read the narratives from these two writers alongside each other, as Noni Jabavu is Sisonke Msimang’s literary ancestor. By looking at their works alongside each other, this thesis becomes an intergenerational conversation between the past and the present. Using Black feminist thought and migratory subjectivity, this thesis examines the ways in which these writers connect the personal and the political. Noni and Sisonke navigate the private spaces of home in conversation with the political experience of exile and the nation. In the second chapter, I explore home as ekhaya, isizwe and an imaginary homeland. Ekhaya is the isiXhosa word denoting the family home, where there is a network of family rather than a nuclear family. Home is also isizwe: the isiXhosa word which evokes the nation state, which takes on layered meanings in the context of colonialism and apartheid. Home can also be an imaginary homeland, which is an imagined version of home after a long absence such as exile. In the third chapter, I examine three forms of exile: internal exile, estrangement and political exile. Finally, in chapter four, I analyse transnationalism: a border-crossing which raises questions of power, mobility and kinship. Looking at home, exile and transnationalism together allows for an exploration which challenges taken-for-granted ideas about place and identity. These memoirs illuminate the ways in which Black women constitute and reconstitute their identities according to the places which they access through travel.
- Full Text:
- Date Issued: 2020
- Authors: Masola, Athambile
- Date: 2020
- Subjects: Home in literature , Exile (Punishment) in literature , Women authors, Black -- South Africa -- History and criticism , Jabavu, Noni -- Criticism and interpretation , Msimang, Sisonke -- Criticism and interpretation
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/166529 , vital:41376
- Description: This thesis examines the memoirs of two South Africa female writers: Noni Jabavu and Sisonke Msimang. In analysing their memoirs, this thesis sets out to contribute to the scholarship which centres the voices of Black women writers. It explores how both writers interrogate the concepts of home, exile and transnationalism. My focus is on the ways in which the writers theorise questions of belonging, and the extent to which their writing provides the opportunity to give voice to the complex nature of belonging. I read the narratives from these two writers alongside each other, as Noni Jabavu is Sisonke Msimang’s literary ancestor. By looking at their works alongside each other, this thesis becomes an intergenerational conversation between the past and the present. Using Black feminist thought and migratory subjectivity, this thesis examines the ways in which these writers connect the personal and the political. Noni and Sisonke navigate the private spaces of home in conversation with the political experience of exile and the nation. In the second chapter, I explore home as ekhaya, isizwe and an imaginary homeland. Ekhaya is the isiXhosa word denoting the family home, where there is a network of family rather than a nuclear family. Home is also isizwe: the isiXhosa word which evokes the nation state, which takes on layered meanings in the context of colonialism and apartheid. Home can also be an imaginary homeland, which is an imagined version of home after a long absence such as exile. In the third chapter, I examine three forms of exile: internal exile, estrangement and political exile. Finally, in chapter four, I analyse transnationalism: a border-crossing which raises questions of power, mobility and kinship. Looking at home, exile and transnationalism together allows for an exploration which challenges taken-for-granted ideas about place and identity. These memoirs illuminate the ways in which Black women constitute and reconstitute their identities according to the places which they access through travel.
- Full Text:
- Date Issued: 2020
Localising the global: the use of a postmodernist aesthetic in the fiction of Alain Mabanckou
- Authors: Ngulube, Innocent Akilimale
- Date: 2020
- Subjects: Mabanckou, Alain, 1966- , Mabanckou, Alain, 1966- -- Blue, white, red , Mabanckou, Alain, 1966- -- African psycho , Mabanckou, Alain, 1966- -- Broken glass , Mabanckou, Alain, 1966- -- Memoirs of a porcupine , Mabanckou, Alain, 1966- -- The Lights of Pointe-Noire , Mabanckou, Alain, 1966- -- Tomorrow I'll be twenty , Mabanckou, Alain, 1966- Black bazaar , Postcolonialism in literature , African fiction (French) -- History and criticism , Postmodernism (Literature)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167153 , vital:41442
- Description: This thesis explores the use of a postmodernist aesth etic in Alain Mabanckou’s oeuvre, namely Blue White Red, African Psycho, Broken Glass, Memoirs of a Porcupine, Black Bazaar, Tomorrow I’ll Be Twenty, The Lights of Pointe-Noire, and Black Moses. In particular, I show how and why this Afrodiasporic author localises strategies associated with Western postmodernist writing in an African postcolonial context. My central argument is that if postmodernism is a critique of modernity in the West, then it must also be a respon se to enforced modernity in the African postcolonial context. In mounting this argument, I conduct a close reading of Mabanckou’s novels from within the theoretical frameworks of postmodernism and postcolonialism. I demonstrate that Mabanckou’s writing adu mbrates the possibility of a postcolonial postmodernism. Since he is a French-Congolese citizen, his writing evinces aesthetic glocalisation. That is, as a postcolonial writer, he conceives of, and inflects, postmodernism differently from a Western writer, for his experiences of and responses to modernity differ from the latter’s. Far from replicating a politics of disillusionment and despair that informs, even characterises, Western postmodernist fiction, Mabanckou invests hi s African postcolonial writing with a politics of decolonis ation which problematises the effects of enforced modernity. Postmodernism, in other words, accords Mabanckou an ambivalent position from which he interrogates both Western modernity and its African version. Significantly, in this regard, Mabanckou’s writing presents both an extension of and a departure from the pioneering influence of the first generation of African writers such as Chinua Achebe, Ngugi wa Thiong’o, and Wole Soyinka.
- Full Text:
- Date Issued: 2020
- Authors: Ngulube, Innocent Akilimale
- Date: 2020
- Subjects: Mabanckou, Alain, 1966- , Mabanckou, Alain, 1966- -- Blue, white, red , Mabanckou, Alain, 1966- -- African psycho , Mabanckou, Alain, 1966- -- Broken glass , Mabanckou, Alain, 1966- -- Memoirs of a porcupine , Mabanckou, Alain, 1966- -- The Lights of Pointe-Noire , Mabanckou, Alain, 1966- -- Tomorrow I'll be twenty , Mabanckou, Alain, 1966- Black bazaar , Postcolonialism in literature , African fiction (French) -- History and criticism , Postmodernism (Literature)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167153 , vital:41442
- Description: This thesis explores the use of a postmodernist aesth etic in Alain Mabanckou’s oeuvre, namely Blue White Red, African Psycho, Broken Glass, Memoirs of a Porcupine, Black Bazaar, Tomorrow I’ll Be Twenty, The Lights of Pointe-Noire, and Black Moses. In particular, I show how and why this Afrodiasporic author localises strategies associated with Western postmodernist writing in an African postcolonial context. My central argument is that if postmodernism is a critique of modernity in the West, then it must also be a respon se to enforced modernity in the African postcolonial context. In mounting this argument, I conduct a close reading of Mabanckou’s novels from within the theoretical frameworks of postmodernism and postcolonialism. I demonstrate that Mabanckou’s writing adu mbrates the possibility of a postcolonial postmodernism. Since he is a French-Congolese citizen, his writing evinces aesthetic glocalisation. That is, as a postcolonial writer, he conceives of, and inflects, postmodernism differently from a Western writer, for his experiences of and responses to modernity differ from the latter’s. Far from replicating a politics of disillusionment and despair that informs, even characterises, Western postmodernist fiction, Mabanckou invests hi s African postcolonial writing with a politics of decolonis ation which problematises the effects of enforced modernity. Postmodernism, in other words, accords Mabanckou an ambivalent position from which he interrogates both Western modernity and its African version. Significantly, in this regard, Mabanckou’s writing presents both an extension of and a departure from the pioneering influence of the first generation of African writers such as Chinua Achebe, Ngugi wa Thiong’o, and Wole Soyinka.
- Full Text:
- Date Issued: 2020
Mechanism of action of non-synonymous single nucleotide variations associated with α-carbonic anhydrases II, IV and VIII
- Authors: Sanyanga, T. Allan
- Date: 2020
- Subjects: Carbonic anhydrase , Carbonic anhydrase -- Therapeutic use , Nucleotides
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167346 , vital:41470
- Description: The carbonic anhydrase (CA) group of enzymes are Zinc (Zn2+) metalloproteins responsible for the reversible hydration of CO2 to bicarbonate (BCT or HCO− 3 ) and protons (H+) for the facilitation of acid-base balance and homeostasis within the body. Across all organisms, a minimum of six CA families exist, including, α (alpha), β (beta), γ (gamma), δ (delta), η (eta) and ζ (zeta). Some organisms can have more than one family, with exception to humans that contain the α family solely. The α-CA family comprises of 16 isoforms (CA-I to CA-XV) including the CA-VIII, CA-X and CA-XI acatalytic isoforms. Of the catalytic isoforms, CA-II and CA-IV possess one of the fastest rates of reaction, and any disturbances to the function of these enzymes results in CA deficiencies and undesirable phenotypes. CA-II deficiencies result in osteopetrosis with renal tubular acidosis and cerebral calcification, whereas CA-IV deficiencies result in retinitis pigmentosa 17 (RP17). Phenotypic effects generally manifest as a result of poor protein folding and function due to the presence of non-synonymous single nucleotide variations (nsSNVs). Even within the acatalytic isoforms such as CA-VIII that llosterically regulates the affinity of inositol triphosphate (IP3) for the IP3 receptor type 1 (ITPR1) and regulates calcium (Ca2+) signalling, the presence of SNVs also causes phenotypes cerebellar ataxia, mental retardation, and dysequilibrium syndrome 3 (CAMRQ3). Currently the majority of research into the CAs is focused on the inhibition of these proteins to achieve therapeutic effects in patients via the control of HCO− production or reabsorption as observed in glaucoma and diuretic medications. Little research has therefore been devoted into the identification of stabilising or activating compound that could rescue protein function in the case of deficiencies. The main aim of this research was to identify and characterise the effects of nsSNVs on the structure and function of CA-II, CA-IV and CA-VIII to set a foundation for rare disease studies into the CA group of proteins. Combined bioinformatics approaches divided into four main objectives were implemented. These included variant identification, sequence analysis and protein characterisation, force field (FF) parameter generation, molecular dynamics (MD) simulation and dynamic residue network analysis (DRN). Six variants for each of the CA-II, CA-IV and CA-VIII proteins with pathogenic annotations were identified from the HUMA and Ensembl databases. These included the pathogenic variants K18E, K18Q, H107Y, P236H, P236R and N252D for CA-II. CA-IV included the pathogenic R69H, R219C and R219S, and benign N86K, N177K and V234I variants. CA-VIII included pathogenic S100A, S100P, G162R and R237Q, and benign S100L and E109D variants. CA-II has been more extensively studied than CA-IV and CA-VIII, therefore residues essential to its function and stability are known. To discover important residues and regions within the CA-IV and CA-VIII proteins sequence and motif analysis was performed across the α-CA family, using CA-II as a reference. Sequence analysis identified multiple conserved residues between the two acatalytic CA-II and CA-IV, and the acatalytic CA-VIII isoforms that were proposed to be essential for protein stability. With exception to the benign N86K CA-IV variant, none of the other pathogenic or benign CA-II, CA-IV and CA-VIII SNVs were located at functionally or structurally important residues. Motif analysis identified 11 conserved and important motifs within the α-CA family. Several of the identified variants were located on these motifs including K18E, K18Q, H107Y and N252D (CA-II); N86K, R219C, R219S and V234I (CA-IV); and E109D, G162R and R237Q (CA-VIII). As there were no x-ray crystal structures of the variant proteins, homology modelling was performed to calculate the protein structures for characterisation. In CA-VIII, the substitution of Ser for Pro at position 100 (variant S100P) resulted in destruction of the β-sheet that the SNV was located on. Little is known about the mechanism of interaction between CA-VIII and ITPR1, and residues involved. SiteMap and CPORT were used to identify binding site amino for CA-VIII and results identified 38 potential residues. Traditional FFs are incapable of performing MD simulations of metalloproteins. The AMBER ff14SB FF was extended and Zn2+ FF parameters calculated to add support for metalloprotein MD simulations. In the protein, Zn2+ was noted to have a charge less than +1. Variant effects on protein structure were then investigated using MD simulations. Root mean square deviation (RMSD) and radius of gyration (Rg) results indicated subtle SNV effects to the variant global structure in CA-II and CA-IV. However, with regards to CA-VIII RMSD analysis highlighted that variant presence was associated with increases to the structural rigidity of the protein. Principal component analysis (PCA) in conjunction with free energy analysis was performed to observe variant effects on protein conformational sampling in 3D space. The binding of BCT to CA-II induced greater protein conformational sampling and was associated with higher free energy. In CA-IV and CA-VIII PCA analysis revealed key differences in the mechanism of action of pathogenic and benign SNVs. In CA-IV, wild-type (WT) and benign variant protein structures clustered into single low energy well hinting at the presence of more stable structures. Pathogenic variants were associated with higher free energy and proteins sampled more conformations without settling into a low energy well. PCA analysis of CA-VIII indicated the opposite to CA-IV. Pathogenic variants were clustered into low energy wells, while the WT and benign variants showed greater conformational sampling. Dynamic cross correlation (DCC) analysis was performed using the MD-TASK suite to determine variant effects on residue movement. CA-II WT protein revealed that BCT and CO2 were associated with anti-correlated and correlated residue movement, highlighting at opposite mechanisms. In CA-IV and CA-VIII variant presence resulted in a change to residue correlation compared to the WT proteins. DRN analysis was performed to investigate SNV effects of residue accessibility and communication. Results demonstrated that SNVs are associated with allosteric effects on the CA protein structures, and effects are located on the stability assisting residues of the aromatic clusters and the active site of the proteins. CA-II studies discovered that Glu117 is the most important residue for communication, and variant presence results in a decrease to the usage of the residue. This effect was greatest in the CA-II H107Y SNV, and suggests that variants could have an effect on Zn2+ dissociation from the active site. Decreases to the usage of Zn2+ coordinating residues were also noted. Where this occurred, compensatory increases to the usage of other primary and secondary coordination residues were observed, that could possibly assist with the maintenance of Zn2+ within the active site. The CA-IV variants R69H and R219C highlighted potentially similar pathogenic mechanisms, whereas N86K and N177K hinted at potentially similar benign mechanisms. Within CA-VIII, variant presence was associated with changes to the accessibility of the N-terminal binding site residues. The benign CA-VIII variants highlighted possible compensatory mechanisms, whereby as one group of N-terminal residues loses accessibility, there was an increase to the accessibility of other binding site residues to possibly balance the effect. Catalytically, the proton shuttle residue His64 in CA-II was found to occupy a novel conformation named the “faux in” that brought the imidazole group even closer to the Zn2+ compared to the “in” conformation. Overall, compared to traditional MD simulations the incorporation of DRN allowed more detailed investigations into the variant mechanisms of action. This highlights the importance of network analysis in the study of the effects of missense mutations on the structure and function of proteins. Investigations of diseases at the molecular level is essential in the identification of disease pathogenesis and assists with the development of specifically tailored and better treatment options especially in the cases of genetically associated rare diseases.
- Full Text:
- Date Issued: 2020
- Authors: Sanyanga, T. Allan
- Date: 2020
- Subjects: Carbonic anhydrase , Carbonic anhydrase -- Therapeutic use , Nucleotides
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167346 , vital:41470
- Description: The carbonic anhydrase (CA) group of enzymes are Zinc (Zn2+) metalloproteins responsible for the reversible hydration of CO2 to bicarbonate (BCT or HCO− 3 ) and protons (H+) for the facilitation of acid-base balance and homeostasis within the body. Across all organisms, a minimum of six CA families exist, including, α (alpha), β (beta), γ (gamma), δ (delta), η (eta) and ζ (zeta). Some organisms can have more than one family, with exception to humans that contain the α family solely. The α-CA family comprises of 16 isoforms (CA-I to CA-XV) including the CA-VIII, CA-X and CA-XI acatalytic isoforms. Of the catalytic isoforms, CA-II and CA-IV possess one of the fastest rates of reaction, and any disturbances to the function of these enzymes results in CA deficiencies and undesirable phenotypes. CA-II deficiencies result in osteopetrosis with renal tubular acidosis and cerebral calcification, whereas CA-IV deficiencies result in retinitis pigmentosa 17 (RP17). Phenotypic effects generally manifest as a result of poor protein folding and function due to the presence of non-synonymous single nucleotide variations (nsSNVs). Even within the acatalytic isoforms such as CA-VIII that llosterically regulates the affinity of inositol triphosphate (IP3) for the IP3 receptor type 1 (ITPR1) and regulates calcium (Ca2+) signalling, the presence of SNVs also causes phenotypes cerebellar ataxia, mental retardation, and dysequilibrium syndrome 3 (CAMRQ3). Currently the majority of research into the CAs is focused on the inhibition of these proteins to achieve therapeutic effects in patients via the control of HCO− production or reabsorption as observed in glaucoma and diuretic medications. Little research has therefore been devoted into the identification of stabilising or activating compound that could rescue protein function in the case of deficiencies. The main aim of this research was to identify and characterise the effects of nsSNVs on the structure and function of CA-II, CA-IV and CA-VIII to set a foundation for rare disease studies into the CA group of proteins. Combined bioinformatics approaches divided into four main objectives were implemented. These included variant identification, sequence analysis and protein characterisation, force field (FF) parameter generation, molecular dynamics (MD) simulation and dynamic residue network analysis (DRN). Six variants for each of the CA-II, CA-IV and CA-VIII proteins with pathogenic annotations were identified from the HUMA and Ensembl databases. These included the pathogenic variants K18E, K18Q, H107Y, P236H, P236R and N252D for CA-II. CA-IV included the pathogenic R69H, R219C and R219S, and benign N86K, N177K and V234I variants. CA-VIII included pathogenic S100A, S100P, G162R and R237Q, and benign S100L and E109D variants. CA-II has been more extensively studied than CA-IV and CA-VIII, therefore residues essential to its function and stability are known. To discover important residues and regions within the CA-IV and CA-VIII proteins sequence and motif analysis was performed across the α-CA family, using CA-II as a reference. Sequence analysis identified multiple conserved residues between the two acatalytic CA-II and CA-IV, and the acatalytic CA-VIII isoforms that were proposed to be essential for protein stability. With exception to the benign N86K CA-IV variant, none of the other pathogenic or benign CA-II, CA-IV and CA-VIII SNVs were located at functionally or structurally important residues. Motif analysis identified 11 conserved and important motifs within the α-CA family. Several of the identified variants were located on these motifs including K18E, K18Q, H107Y and N252D (CA-II); N86K, R219C, R219S and V234I (CA-IV); and E109D, G162R and R237Q (CA-VIII). As there were no x-ray crystal structures of the variant proteins, homology modelling was performed to calculate the protein structures for characterisation. In CA-VIII, the substitution of Ser for Pro at position 100 (variant S100P) resulted in destruction of the β-sheet that the SNV was located on. Little is known about the mechanism of interaction between CA-VIII and ITPR1, and residues involved. SiteMap and CPORT were used to identify binding site amino for CA-VIII and results identified 38 potential residues. Traditional FFs are incapable of performing MD simulations of metalloproteins. The AMBER ff14SB FF was extended and Zn2+ FF parameters calculated to add support for metalloprotein MD simulations. In the protein, Zn2+ was noted to have a charge less than +1. Variant effects on protein structure were then investigated using MD simulations. Root mean square deviation (RMSD) and radius of gyration (Rg) results indicated subtle SNV effects to the variant global structure in CA-II and CA-IV. However, with regards to CA-VIII RMSD analysis highlighted that variant presence was associated with increases to the structural rigidity of the protein. Principal component analysis (PCA) in conjunction with free energy analysis was performed to observe variant effects on protein conformational sampling in 3D space. The binding of BCT to CA-II induced greater protein conformational sampling and was associated with higher free energy. In CA-IV and CA-VIII PCA analysis revealed key differences in the mechanism of action of pathogenic and benign SNVs. In CA-IV, wild-type (WT) and benign variant protein structures clustered into single low energy well hinting at the presence of more stable structures. Pathogenic variants were associated with higher free energy and proteins sampled more conformations without settling into a low energy well. PCA analysis of CA-VIII indicated the opposite to CA-IV. Pathogenic variants were clustered into low energy wells, while the WT and benign variants showed greater conformational sampling. Dynamic cross correlation (DCC) analysis was performed using the MD-TASK suite to determine variant effects on residue movement. CA-II WT protein revealed that BCT and CO2 were associated with anti-correlated and correlated residue movement, highlighting at opposite mechanisms. In CA-IV and CA-VIII variant presence resulted in a change to residue correlation compared to the WT proteins. DRN analysis was performed to investigate SNV effects of residue accessibility and communication. Results demonstrated that SNVs are associated with allosteric effects on the CA protein structures, and effects are located on the stability assisting residues of the aromatic clusters and the active site of the proteins. CA-II studies discovered that Glu117 is the most important residue for communication, and variant presence results in a decrease to the usage of the residue. This effect was greatest in the CA-II H107Y SNV, and suggests that variants could have an effect on Zn2+ dissociation from the active site. Decreases to the usage of Zn2+ coordinating residues were also noted. Where this occurred, compensatory increases to the usage of other primary and secondary coordination residues were observed, that could possibly assist with the maintenance of Zn2+ within the active site. The CA-IV variants R69H and R219C highlighted potentially similar pathogenic mechanisms, whereas N86K and N177K hinted at potentially similar benign mechanisms. Within CA-VIII, variant presence was associated with changes to the accessibility of the N-terminal binding site residues. The benign CA-VIII variants highlighted possible compensatory mechanisms, whereby as one group of N-terminal residues loses accessibility, there was an increase to the accessibility of other binding site residues to possibly balance the effect. Catalytically, the proton shuttle residue His64 in CA-II was found to occupy a novel conformation named the “faux in” that brought the imidazole group even closer to the Zn2+ compared to the “in” conformation. Overall, compared to traditional MD simulations the incorporation of DRN allowed more detailed investigations into the variant mechanisms of action. This highlights the importance of network analysis in the study of the effects of missense mutations on the structure and function of proteins. Investigations of diseases at the molecular level is essential in the identification of disease pathogenesis and assists with the development of specifically tailored and better treatment options especially in the cases of genetically associated rare diseases.
- Full Text:
- Date Issued: 2020
Modelling and investigating primary beam effects of reflector antenna arrays
- Authors: Iheanetu, Kelachukwu
- Date: 2020
- Subjects: Antennas, Reflector , Radio telescopes , Astronomical instruments -- Calibration , Holography , Polynomials , Very large array telescopes -- South Africa , Astronomy -- Data processing , Primary beam effects , Jacobi-Bessel pattern , Cassbeam software , MeerKAT telescope
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/147425 , vital:38635
- Description: Signals received by a radio telescope are always affected by propagation and instrumental effects. These effects need to be modelled and accounted for during the process of calibration. The primary beam (PB) of the antenna is one major instrumental effect that needs to be accounted for during calibration. Producing accurate models of the radio antenna PB is crucial, and many approaches (like electromagnetic and optical simulations) have been used to model it. The cos³ function, Jacobi-Bessel pattern, characteristic basis function patterns (CBFP) and Cassbeam software (which uses optical ray-tracing with antenna parameters) have also been used to model it. These models capture the basic PB effects. Real-life PB patterns differ from these models due to various subtle effects such as mechanical deformation and effects introduced into the PB due to standing waves that exist in reflector antennas. The actual patterns can be measured via a process called astro-holography (or holography), but this is subject to noise, radio frequency interference, and other measurement errors. In our approach, we use principal component analysis and Zernike polynomials to model the PBs of the Very Large Array (VLA) and the MeerKAT telescopes from their holography measured data. The models have reconstruction errors of less than 5% at a compression factor of approximately 98% for both arrays. We also present steps that can be used to generate accurate beam models for any telescope (independent of its design) based on holography measured data. Analysis of the VLA measured PBs revealed that the graph of the beam sizes (and centre offset positions) have a fast oscillating trend (superimposed on a slow trend) with frequency. This spectral behaviour we termed ripple or characteristic effects. Most existing PB models that are used in calibrating VLA data do not incorporate these direction dependent effects (DDEs). We investigate the impact of using PB models that ignore this DDE in continuum calibration and imaging via simulations. Our experiments show that, although these effects translate into less than 10% errors in source flux recovery, they do lead to 30% reduction in the dynamic range. To prepare data for Hi and radio halo (faint emissions) science analysis requires carrying out foreground subtraction of bright (continuum) sources. We investigate the impact of using beam models that ignore these ripple effects during continuum subtraction. These show that using PB models which completely ignore the ripple effects in continuum subtraction could translate to error of more to 30% in the recovered Hi spectral properties. This implies that science inferences drawn from the results for Hi studies could have errors of the same magnitude.
- Full Text:
- Date Issued: 2020
- Authors: Iheanetu, Kelachukwu
- Date: 2020
- Subjects: Antennas, Reflector , Radio telescopes , Astronomical instruments -- Calibration , Holography , Polynomials , Very large array telescopes -- South Africa , Astronomy -- Data processing , Primary beam effects , Jacobi-Bessel pattern , Cassbeam software , MeerKAT telescope
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/147425 , vital:38635
- Description: Signals received by a radio telescope are always affected by propagation and instrumental effects. These effects need to be modelled and accounted for during the process of calibration. The primary beam (PB) of the antenna is one major instrumental effect that needs to be accounted for during calibration. Producing accurate models of the radio antenna PB is crucial, and many approaches (like electromagnetic and optical simulations) have been used to model it. The cos³ function, Jacobi-Bessel pattern, characteristic basis function patterns (CBFP) and Cassbeam software (which uses optical ray-tracing with antenna parameters) have also been used to model it. These models capture the basic PB effects. Real-life PB patterns differ from these models due to various subtle effects such as mechanical deformation and effects introduced into the PB due to standing waves that exist in reflector antennas. The actual patterns can be measured via a process called astro-holography (or holography), but this is subject to noise, radio frequency interference, and other measurement errors. In our approach, we use principal component analysis and Zernike polynomials to model the PBs of the Very Large Array (VLA) and the MeerKAT telescopes from their holography measured data. The models have reconstruction errors of less than 5% at a compression factor of approximately 98% for both arrays. We also present steps that can be used to generate accurate beam models for any telescope (independent of its design) based on holography measured data. Analysis of the VLA measured PBs revealed that the graph of the beam sizes (and centre offset positions) have a fast oscillating trend (superimposed on a slow trend) with frequency. This spectral behaviour we termed ripple or characteristic effects. Most existing PB models that are used in calibrating VLA data do not incorporate these direction dependent effects (DDEs). We investigate the impact of using PB models that ignore this DDE in continuum calibration and imaging via simulations. Our experiments show that, although these effects translate into less than 10% errors in source flux recovery, they do lead to 30% reduction in the dynamic range. To prepare data for Hi and radio halo (faint emissions) science analysis requires carrying out foreground subtraction of bright (continuum) sources. We investigate the impact of using beam models that ignore these ripple effects during continuum subtraction. These show that using PB models which completely ignore the ripple effects in continuum subtraction could translate to error of more to 30% in the recovered Hi spectral properties. This implies that science inferences drawn from the results for Hi studies could have errors of the same magnitude.
- Full Text:
- Date Issued: 2020
Mothers’ perceptions of the effects of the babies in mind programme on maternal mental health and mother-infant attachment: a South African narrative study
- Naicker, Samantha, Cronje, Johan
- Authors: Naicker, Samantha , Cronje, Johan
- Date: 2020
- Subjects: Mother and infant
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/46414 , vital:39590
- Description: The focus of this study is on mothers, motherhood and the Babies in Mind programme as an early intervention strategy for mothers in South Africa. The rate of maternal mental ill health in our country is alarming. Research consistently confirms that maternal mental health directly affects infant and child mental health. One of the major determinants of mental health is mother-infant attachment. Studies have indicated the range of deleterious effects that maternal mental ill-health and mother-infant attachment issues have on offspring from infancy to adulthood. This has implications for the mental health of future generations and society at large. Researchers have called for evidence-based interventions that address maternal mental health and mother-infant attachment, especially in developing countries. South Africa has no national prevention or treatment programme to address these needs. This study investigated the Babies in Mind programme as an early intervention option to address the gap in promoting maternal mental health and mother-infant attachment. A social constructionist, narrative study was employed to meet the objectives of the study. The aim was to explore mothers’ perceptions of the impact of the Babies in Mind programme, with particular reference to their mental health and their relationships to their infants. Focus was placed on understanding the social constructions of motherhood at the community level and how these constructions were reconstructed through the programme. Purposive sampling was employed and focus groups were conducted to collect the relevant data. The data was analysed using thematic analysis. The findings indicated that mothers’ experiences of the Babies in Mind programme were positive and there were improvements in their mental health and relationships to their infants. A relationship model for mothers was developed based on the themes that emerged from the data analysis. A platform for continued support and discussion was organised via a social media (Whatsapp) support group. Twelve 7guidelines were suggested for the implementation of intervention programmes such as the Babies in Mind programme at the community level.
- Full Text:
- Date Issued: 2020
- Authors: Naicker, Samantha , Cronje, Johan
- Date: 2020
- Subjects: Mother and infant
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/46414 , vital:39590
- Description: The focus of this study is on mothers, motherhood and the Babies in Mind programme as an early intervention strategy for mothers in South Africa. The rate of maternal mental ill health in our country is alarming. Research consistently confirms that maternal mental health directly affects infant and child mental health. One of the major determinants of mental health is mother-infant attachment. Studies have indicated the range of deleterious effects that maternal mental ill-health and mother-infant attachment issues have on offspring from infancy to adulthood. This has implications for the mental health of future generations and society at large. Researchers have called for evidence-based interventions that address maternal mental health and mother-infant attachment, especially in developing countries. South Africa has no national prevention or treatment programme to address these needs. This study investigated the Babies in Mind programme as an early intervention option to address the gap in promoting maternal mental health and mother-infant attachment. A social constructionist, narrative study was employed to meet the objectives of the study. The aim was to explore mothers’ perceptions of the impact of the Babies in Mind programme, with particular reference to their mental health and their relationships to their infants. Focus was placed on understanding the social constructions of motherhood at the community level and how these constructions were reconstructed through the programme. Purposive sampling was employed and focus groups were conducted to collect the relevant data. The data was analysed using thematic analysis. The findings indicated that mothers’ experiences of the Babies in Mind programme were positive and there were improvements in their mental health and relationships to their infants. A relationship model for mothers was developed based on the themes that emerged from the data analysis. A platform for continued support and discussion was organised via a social media (Whatsapp) support group. Twelve 7guidelines were suggested for the implementation of intervention programmes such as the Babies in Mind programme at the community level.
- Full Text:
- Date Issued: 2020