Development of titanium dioxide for photo-electrochemical hydrogen production
- Authors: Mbulanga, Crispin Munyelele
- Date: 2019
- Subjects: Titanium dioxide , Nanostructured materials Water chemistry Environmental chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/40735 , vital:36231
- Description: TiO2 is an attractive material for photo electrochemical hydrogen production and in this work the synthesis of this compound by hydrothermal, gel-calcination and one-step templating methods is investigated. Rutile-phase TiO2 rods, which are known to offer direct electrical pathways for photo generated electrons when using TiO2 as a photo anode in a photo-electrochemical hydrogen cell, were prepared on both F:SnO2 (FTO) coated glass and Ti foil substrates. Anatase-phase TiO2 tubes and mixed rutile-anatase-phase TiO2 nanostructured films were developed on FTO-coated glass substrates. Rutile-phase TiO2 rod-like structures, were synthesized hydrothermally at 150 oC for different times (6 – 20 hours) on FTO-coated glass substrate, in an aqueous solution of hydrochloric acid and titanium butoxide. The rod-like structures were found to comprise bundles of crystalline prismatic TiO2 nanorods, each approximately 4 nm in width. Each bundle was tetragonal in shape and highly oriented with respect to the substrate surface. The average diameter of the bundles varied depending on the growth time, and reached a mean diameter of ~175 nm after 20 hours of growth. In terms of Raman scattering, these bundles of nanorods acted as single entities, appearing to act as “larger” crystals to the lattice phonons. Hence, phonon confinement effects could not be observed, because the translational symmetry is preserved at the boundaries between individual rods. Moreover, as the preferential perpendicular orientation of the bundles improved with growth time, an unusual increase in the room and low (77K) temperature Eg/A1g Raman band intensity ratios was observed. The low temperature Raman peak position and peak width data was interpreted as supporting the hypothesis that the bundles of nanorods acting as single entities from the point of view of the lattice phonons. The phonon symmetries and frequencies (in cm-1) of these bundles of rutile-phase TiO2 were found to be consistent with rutile-phase TiO2 phonon symmetries and frequencies. Rutile-phase TiO2 rod-like structures were prepared on Ti foil following a two-step gel-calcination method, which involves a gel-deposition process in 5 M NaOH solution at 76 oC for 24 hours to produce a Na- (and Ti-) based layer of gelatinous material, followed by calcination at 600 oC or 800 oC for 1 hour. It is shown that the use of an alkali-based solution such as NaOH and KOH during gel-deposition, leads to the formation of faceted nanorods of rutile-phase TiO2 upon calcination at high temperature. When a solution that does not contain any alkali element, such as H2O2, was used, the material formed upon calcination at 800 oC were clustered nanoparticles, rather than nanorods. From the experiments it was deduced that the high temperature calcination step converted the Na(or K)-based amorphous gel (formed on the Ti surface during a 24-h soak in NaOH (KOH) solution) into faceted Na-titanate rods, which converted into nanorods of rutile-phase TiO2 when Na(or K) evaporates in the form of an oxide. Anatase-phase TiO2 tube-like structures were produced by a one-step templating solution approach, on FTO-coated glass substrate. ZnO nanorod templates were prepared by chemical bath deposition on FTO-coated glass substrate, and then treated in an aqueous mixture of ammonium hexafluorotitanate and boric acid. To study the effect of the template morphology and deposition processes on the formation of anatase TiO2 tubes, different times (10 – 60 minutes) and concentrations of the precursors are used. Calcination at 550 oC converted the Ti-based material developed on the ZnO rods into TiO2 nanostructures. A 10 minute deposition yielded tubes with dimensions resembling those of the ZnO template. However, the tube walls still contained Zn traces. Based on experimental observations, it was concluded that the production of titanium hydroxide complexes on ZnO surfaces takes place through two competing processes: the development of a Ti-based material and partial dissolution of ZnO along the c-axis. Calcination at 550 oC in air finally yielded anatase TiO2. Mixed rutile-anatase-phase TiO2 nanostructured films on FTO-coated glass substrate were prepared by decorating bundles of crystalline prismatic TiO2 nanorods (prepared hydrothermally) with anatase-phase TiO2 particles, using the same precursors mentioned above. The effect of reaction time and precursor concentrations were investigated. It was found that the precursor concentration ratio and reaction time played key roles in controlling the decoration process. Optimal ratios and decoration times were established based on the density of anatase-phase TiO2 decorating particles on the surface of bundles of rutile-phase TiO2 nanorods. The optical properties of rutile-phase TiO2 rods were investigated. The thickness of the TiO2 layer was calculated from reflectance fringes, and agreed well with the length of rods observed using SEM. The room temperature absorption edge of Eg=2.90 eV extracted from the transmittance spectrum correlated with typical values reported for TiO2. The room temperature absorption edge of the conductive layer of F:SnO2 (Eg=3.56 eV) could also be extracted from the transmittance spectrum. Finally, the absorption of white light by rutile-phase TiO2 rods was confirmed to be enhanced by annealing the rods in either hydrogen or nitrogen at 600 oC. Defects (possibly oxygen vacancies) or disorder in the near surface layers of TiO2 induced during the reduction experiments, created new electronic states in the band gap, as reported in literature.
- Full Text:
- Date Issued: 2019
- Authors: Mbulanga, Crispin Munyelele
- Date: 2019
- Subjects: Titanium dioxide , Nanostructured materials Water chemistry Environmental chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/40735 , vital:36231
- Description: TiO2 is an attractive material for photo electrochemical hydrogen production and in this work the synthesis of this compound by hydrothermal, gel-calcination and one-step templating methods is investigated. Rutile-phase TiO2 rods, which are known to offer direct electrical pathways for photo generated electrons when using TiO2 as a photo anode in a photo-electrochemical hydrogen cell, were prepared on both F:SnO2 (FTO) coated glass and Ti foil substrates. Anatase-phase TiO2 tubes and mixed rutile-anatase-phase TiO2 nanostructured films were developed on FTO-coated glass substrates. Rutile-phase TiO2 rod-like structures, were synthesized hydrothermally at 150 oC for different times (6 – 20 hours) on FTO-coated glass substrate, in an aqueous solution of hydrochloric acid and titanium butoxide. The rod-like structures were found to comprise bundles of crystalline prismatic TiO2 nanorods, each approximately 4 nm in width. Each bundle was tetragonal in shape and highly oriented with respect to the substrate surface. The average diameter of the bundles varied depending on the growth time, and reached a mean diameter of ~175 nm after 20 hours of growth. In terms of Raman scattering, these bundles of nanorods acted as single entities, appearing to act as “larger” crystals to the lattice phonons. Hence, phonon confinement effects could not be observed, because the translational symmetry is preserved at the boundaries between individual rods. Moreover, as the preferential perpendicular orientation of the bundles improved with growth time, an unusual increase in the room and low (77K) temperature Eg/A1g Raman band intensity ratios was observed. The low temperature Raman peak position and peak width data was interpreted as supporting the hypothesis that the bundles of nanorods acting as single entities from the point of view of the lattice phonons. The phonon symmetries and frequencies (in cm-1) of these bundles of rutile-phase TiO2 were found to be consistent with rutile-phase TiO2 phonon symmetries and frequencies. Rutile-phase TiO2 rod-like structures were prepared on Ti foil following a two-step gel-calcination method, which involves a gel-deposition process in 5 M NaOH solution at 76 oC for 24 hours to produce a Na- (and Ti-) based layer of gelatinous material, followed by calcination at 600 oC or 800 oC for 1 hour. It is shown that the use of an alkali-based solution such as NaOH and KOH during gel-deposition, leads to the formation of faceted nanorods of rutile-phase TiO2 upon calcination at high temperature. When a solution that does not contain any alkali element, such as H2O2, was used, the material formed upon calcination at 800 oC were clustered nanoparticles, rather than nanorods. From the experiments it was deduced that the high temperature calcination step converted the Na(or K)-based amorphous gel (formed on the Ti surface during a 24-h soak in NaOH (KOH) solution) into faceted Na-titanate rods, which converted into nanorods of rutile-phase TiO2 when Na(or K) evaporates in the form of an oxide. Anatase-phase TiO2 tube-like structures were produced by a one-step templating solution approach, on FTO-coated glass substrate. ZnO nanorod templates were prepared by chemical bath deposition on FTO-coated glass substrate, and then treated in an aqueous mixture of ammonium hexafluorotitanate and boric acid. To study the effect of the template morphology and deposition processes on the formation of anatase TiO2 tubes, different times (10 – 60 minutes) and concentrations of the precursors are used. Calcination at 550 oC converted the Ti-based material developed on the ZnO rods into TiO2 nanostructures. A 10 minute deposition yielded tubes with dimensions resembling those of the ZnO template. However, the tube walls still contained Zn traces. Based on experimental observations, it was concluded that the production of titanium hydroxide complexes on ZnO surfaces takes place through two competing processes: the development of a Ti-based material and partial dissolution of ZnO along the c-axis. Calcination at 550 oC in air finally yielded anatase TiO2. Mixed rutile-anatase-phase TiO2 nanostructured films on FTO-coated glass substrate were prepared by decorating bundles of crystalline prismatic TiO2 nanorods (prepared hydrothermally) with anatase-phase TiO2 particles, using the same precursors mentioned above. The effect of reaction time and precursor concentrations were investigated. It was found that the precursor concentration ratio and reaction time played key roles in controlling the decoration process. Optimal ratios and decoration times were established based on the density of anatase-phase TiO2 decorating particles on the surface of bundles of rutile-phase TiO2 nanorods. The optical properties of rutile-phase TiO2 rods were investigated. The thickness of the TiO2 layer was calculated from reflectance fringes, and agreed well with the length of rods observed using SEM. The room temperature absorption edge of Eg=2.90 eV extracted from the transmittance spectrum correlated with typical values reported for TiO2. The room temperature absorption edge of the conductive layer of F:SnO2 (Eg=3.56 eV) could also be extracted from the transmittance spectrum. Finally, the absorption of white light by rutile-phase TiO2 rods was confirmed to be enhanced by annealing the rods in either hydrogen or nitrogen at 600 oC. Defects (possibly oxygen vacancies) or disorder in the near surface layers of TiO2 induced during the reduction experiments, created new electronic states in the band gap, as reported in literature.
- Full Text:
- Date Issued: 2019
Digital colonialism: South Africa’s education transformation in the shadow of Silicon Valley
- Authors: Kwet, Michael
- Date: 2019
- Subjects: Operation Phakisa Education (South Africa) , Educational technology -- South Africa , Internet in education -- South Africa , Educational sociology -- South Africa , Technological innovations -- South Africa , Technological literacy -- South Africa , Education and state -- South Africa , Open source software -- South Africa , Electronic surveillance -- Social aspects -- South Africa , Privacy, Right of -- South Africa , Business and education -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/93767 , vital:30936
- Description: This dissertation investigates the social implications of technology choices for the emerging education transformation of the South African basic education sector. In October 2015, then President Jacob Zuma launched Operation Phakisa Education (OPE), an initiative designed behind closed doors to fast-track digital education into all South African public schools. This study identifies and analyses policy choices and perspectives regarding the technology considered and deployed for the national education rollout. It documents the OPE proposal, and examines how e-education policy choices relate to humanitarian objectives. Theoretically, this study draws upon libertarian socialist theory (anarchism) to examine the sociology of education technology policy. Using anarchist theory, it assesses the perspective, aims, and choices of e-education policy at the national level. It also draws on the Free Software philosophy for society as articulated by Richard Stallman and Eben Moglen. Finally, it compares classic colonialism with global power in the digital era, and posits a theory of digital colonialism. Synthesizing anarchism and the Free Software philosophy into a single theoretical framework – placed into the context of colonial relations – it is the first work to apply anarchist sociological theory to education technology policy, and the first doctoral study on digital colonialism. For its methodology, this dissertation utilizes two qualitative methods: document analysis and semi-structured interviews. Interview subjects include high-level e-education policymakers and administrators in government, key stakeholders, and experts at the intersection of technology innovation and human rights. These methods were used to both identify and interrogate e-education policy as it relates to the humanitarian objectives of education policy at the national level. The findings demonstrate that South African education policy is beholden to largely United States-based corporations and models for e-education. The study found that the types of technologies for consideration in education are rooted in surveillance capitalism, which is spreading across the world. It contends that current e-education policy choices will entrench the power and exploitation of US state-corporate power in South African education, economy, and society. It argues that an alternative set of choices, People’s Technology for People’s Power, is consistent with the spirit of South African technology policy, and should be chosen for South African schools in order to counter the power of foreign power and resist surveillance capitalism. This dissertation is the first publication to document and analyze what the new government education policy is about and how it relates to equality and human rights. It argues that present South African e-education policy constitutes a new form of digitally-driven technocratic neoliberalism which ultimately favors ruling class interests in the United States and South Africa. It also argues that OPE violates South Africa’s Free and Open Source policy and the spirit of democracy outlined in the Phakisa methodology and the Batho Pele principles. This study found that OPE replicates the latest trends in e-education implementation popular in Silicon Valley. Tech multinationals are providing both the products and models for use in South Africa. The dissertation concludes that US technological and conceptual dominance in South African education constitutes digital colonialism. It emphasizes the need for public inclusion in the policy process, and proposes alternative policies and technologies for e-education based on the idea of People’s Technology for People’s Power. It also argues that current scholarship on education technology neglects the political and sociological importance of People’s Technology to education, economy, and society, as well as the global significance of Big Tech dominance vis-a-vis digital colonialism, and that subsequent literature would be enriched by addressing these issues.
- Full Text:
- Date Issued: 2019
- Authors: Kwet, Michael
- Date: 2019
- Subjects: Operation Phakisa Education (South Africa) , Educational technology -- South Africa , Internet in education -- South Africa , Educational sociology -- South Africa , Technological innovations -- South Africa , Technological literacy -- South Africa , Education and state -- South Africa , Open source software -- South Africa , Electronic surveillance -- Social aspects -- South Africa , Privacy, Right of -- South Africa , Business and education -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/93767 , vital:30936
- Description: This dissertation investigates the social implications of technology choices for the emerging education transformation of the South African basic education sector. In October 2015, then President Jacob Zuma launched Operation Phakisa Education (OPE), an initiative designed behind closed doors to fast-track digital education into all South African public schools. This study identifies and analyses policy choices and perspectives regarding the technology considered and deployed for the national education rollout. It documents the OPE proposal, and examines how e-education policy choices relate to humanitarian objectives. Theoretically, this study draws upon libertarian socialist theory (anarchism) to examine the sociology of education technology policy. Using anarchist theory, it assesses the perspective, aims, and choices of e-education policy at the national level. It also draws on the Free Software philosophy for society as articulated by Richard Stallman and Eben Moglen. Finally, it compares classic colonialism with global power in the digital era, and posits a theory of digital colonialism. Synthesizing anarchism and the Free Software philosophy into a single theoretical framework – placed into the context of colonial relations – it is the first work to apply anarchist sociological theory to education technology policy, and the first doctoral study on digital colonialism. For its methodology, this dissertation utilizes two qualitative methods: document analysis and semi-structured interviews. Interview subjects include high-level e-education policymakers and administrators in government, key stakeholders, and experts at the intersection of technology innovation and human rights. These methods were used to both identify and interrogate e-education policy as it relates to the humanitarian objectives of education policy at the national level. The findings demonstrate that South African education policy is beholden to largely United States-based corporations and models for e-education. The study found that the types of technologies for consideration in education are rooted in surveillance capitalism, which is spreading across the world. It contends that current e-education policy choices will entrench the power and exploitation of US state-corporate power in South African education, economy, and society. It argues that an alternative set of choices, People’s Technology for People’s Power, is consistent with the spirit of South African technology policy, and should be chosen for South African schools in order to counter the power of foreign power and resist surveillance capitalism. This dissertation is the first publication to document and analyze what the new government education policy is about and how it relates to equality and human rights. It argues that present South African e-education policy constitutes a new form of digitally-driven technocratic neoliberalism which ultimately favors ruling class interests in the United States and South Africa. It also argues that OPE violates South Africa’s Free and Open Source policy and the spirit of democracy outlined in the Phakisa methodology and the Batho Pele principles. This study found that OPE replicates the latest trends in e-education implementation popular in Silicon Valley. Tech multinationals are providing both the products and models for use in South Africa. The dissertation concludes that US technological and conceptual dominance in South African education constitutes digital colonialism. It emphasizes the need for public inclusion in the policy process, and proposes alternative policies and technologies for e-education based on the idea of People’s Technology for People’s Power. It also argues that current scholarship on education technology neglects the political and sociological importance of People’s Technology to education, economy, and society, as well as the global significance of Big Tech dominance vis-a-vis digital colonialism, and that subsequent literature would be enriched by addressing these issues.
- Full Text:
- Date Issued: 2019
Diversity, host plant range and ecology of Lepidoptera stem borers in South Africa
- Authors: Stemele, Mxolisi Arnold
- Date: 2019
- Subjects: Lepidoptera Host plants Stem borers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15409 , vital:40405
- Description: The biology and ecology of Lepidopteran pests stem borers has been extensively studied because of the economic importance of pest species such as Busseola fusca (Fuller) (Noctuidae), Sesamia calamistis (Hampson) (Noctuidae), Chilo partellus (Swinhoe) (Crambidae), and Eldana saccharina (Walker) (Pyralidae). Knowledge relating to diversity, infestation dynamics, and host plant range is readily available. In natural vegetation, the variety of stem borers is higher than that found in agroecosystems. However, there is a paucity of South African studies that explain the observed differences in diversity between the two systems. Stem borers are also known to exhibit species-specific ecological requirements, which influence their distribution between African countries. South African biomes are classified based on vegetation structure and climate, which happens to be the most critical factors that affect the distribution of phytophagous insects. This makes biomes an excellent model to investigate diversity and distribution of stem borer species. In this study, we investigated diversity, distribution and species composition in four biomes. The results showed that diversity and distribution of the stem borers in natural vegetation was determined by host plant distribution. Stem borer diversity correlated with high diversity of host plants. Thirty-two stem borer species were collected from 27 host plants and another three from light traps. Widely distributed host plants supported a higher diversity of stem borers, which is consistent with the resource availability hypotheses. Non-metric dimensional scale unfolding revealed disparity in host plant preference and plant species composition between the various stem borer families (Kruskal’s Stress = 0.16). Tortricidae species and Sesamia typhae (Le rü) (Noctuidae) feed exclusively on hydrophytic Cyperaceae species. The majority of Noctuidae, Crambidae and Phycitidae species collected were oligophagous on terrestrial Poaceae, with a few polyphagous exceptions feeding on hydrophytic Cyperaceae and Typhaceae. Additionally, species composition of Poaceae host plants differed between 8 Crambidae and the Phycitidae species. Stem borer species composition between biomes revealed the presence of distinct host plants (2D stress = 0.09) and stem borer (2D stress = 0.13) communities. The stem borer abundance and diversity were strongly correlated (R2 = 0.64), but species diversity (R2 = - 0.95) and host plant diversity (R2 = - 0.85) were inversely correlated to altitude. Based on these results it was concluded that stem borer diversity and distribution in natural vegetation was influenced by host plant diversity and distribution as well as climate associated with altitudinal gradients. In the last two decades, four stem borer species previously known on wild host plants; Busseola segeta (Bowden), Busseola phaia (Bowden), Pirateolea piscator (Fletcher) and Conicofrontia sesamoides (Hampson) have invaded cultivated crops. These invasions remained undetected because of a shortage of surveys, habitat transformation and misidentifications. Misidentifications are common among stem borers due to the considerable resemblance between morphospecies. In this study, we assessed the capacity of the mitochondrial gene Cytochrome c oxidase (COI) to delineate closely related species to develop monitoring and early detection of invasive species and to assess migration patterns and gene flow between the populations. The results demonstrated that COI is an effective DNA marker for species delineation and assessment of intra- and interspecific genetic relationship. The K2P distances and phylogenetic tree defined boundaries between Noctuidae species with high resolution. No divergence distance was detected between intraspecific species, but for the congener species, divergence distance was 0.044%-0.111% with an average of 0.076%. The average interspecies K2P distance (0.57%) was 5-15 times higher than the congener species distances. Phylogenetic analysis revealed the presence of two clades. Busseola and Sesamia species were connected in a monophyletic clade with a strong (93%) bootstrap. The second monophyletic clade comprised of a cluster of Pirateolea, Acrapex and Conicofrontia species, and this was also supported with 9 a strong bootstrap (100%). The gene flow study revealed low levels of genetic differentiation between the populations of B. fusca collected from different maize producing areas in South Africa. This low genetic differentiation was consistent with high gene flow. The number of effective migrants between the populations was between 8 and 99 individuals per generation. These results indicate high connectivity between the populations.
- Full Text:
- Date Issued: 2019
- Authors: Stemele, Mxolisi Arnold
- Date: 2019
- Subjects: Lepidoptera Host plants Stem borers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15409 , vital:40405
- Description: The biology and ecology of Lepidopteran pests stem borers has been extensively studied because of the economic importance of pest species such as Busseola fusca (Fuller) (Noctuidae), Sesamia calamistis (Hampson) (Noctuidae), Chilo partellus (Swinhoe) (Crambidae), and Eldana saccharina (Walker) (Pyralidae). Knowledge relating to diversity, infestation dynamics, and host plant range is readily available. In natural vegetation, the variety of stem borers is higher than that found in agroecosystems. However, there is a paucity of South African studies that explain the observed differences in diversity between the two systems. Stem borers are also known to exhibit species-specific ecological requirements, which influence their distribution between African countries. South African biomes are classified based on vegetation structure and climate, which happens to be the most critical factors that affect the distribution of phytophagous insects. This makes biomes an excellent model to investigate diversity and distribution of stem borer species. In this study, we investigated diversity, distribution and species composition in four biomes. The results showed that diversity and distribution of the stem borers in natural vegetation was determined by host plant distribution. Stem borer diversity correlated with high diversity of host plants. Thirty-two stem borer species were collected from 27 host plants and another three from light traps. Widely distributed host plants supported a higher diversity of stem borers, which is consistent with the resource availability hypotheses. Non-metric dimensional scale unfolding revealed disparity in host plant preference and plant species composition between the various stem borer families (Kruskal’s Stress = 0.16). Tortricidae species and Sesamia typhae (Le rü) (Noctuidae) feed exclusively on hydrophytic Cyperaceae species. The majority of Noctuidae, Crambidae and Phycitidae species collected were oligophagous on terrestrial Poaceae, with a few polyphagous exceptions feeding on hydrophytic Cyperaceae and Typhaceae. Additionally, species composition of Poaceae host plants differed between 8 Crambidae and the Phycitidae species. Stem borer species composition between biomes revealed the presence of distinct host plants (2D stress = 0.09) and stem borer (2D stress = 0.13) communities. The stem borer abundance and diversity were strongly correlated (R2 = 0.64), but species diversity (R2 = - 0.95) and host plant diversity (R2 = - 0.85) were inversely correlated to altitude. Based on these results it was concluded that stem borer diversity and distribution in natural vegetation was influenced by host plant diversity and distribution as well as climate associated with altitudinal gradients. In the last two decades, four stem borer species previously known on wild host plants; Busseola segeta (Bowden), Busseola phaia (Bowden), Pirateolea piscator (Fletcher) and Conicofrontia sesamoides (Hampson) have invaded cultivated crops. These invasions remained undetected because of a shortage of surveys, habitat transformation and misidentifications. Misidentifications are common among stem borers due to the considerable resemblance between morphospecies. In this study, we assessed the capacity of the mitochondrial gene Cytochrome c oxidase (COI) to delineate closely related species to develop monitoring and early detection of invasive species and to assess migration patterns and gene flow between the populations. The results demonstrated that COI is an effective DNA marker for species delineation and assessment of intra- and interspecific genetic relationship. The K2P distances and phylogenetic tree defined boundaries between Noctuidae species with high resolution. No divergence distance was detected between intraspecific species, but for the congener species, divergence distance was 0.044%-0.111% with an average of 0.076%. The average interspecies K2P distance (0.57%) was 5-15 times higher than the congener species distances. Phylogenetic analysis revealed the presence of two clades. Busseola and Sesamia species were connected in a monophyletic clade with a strong (93%) bootstrap. The second monophyletic clade comprised of a cluster of Pirateolea, Acrapex and Conicofrontia species, and this was also supported with 9 a strong bootstrap (100%). The gene flow study revealed low levels of genetic differentiation between the populations of B. fusca collected from different maize producing areas in South Africa. This low genetic differentiation was consistent with high gene flow. The number of effective migrants between the populations was between 8 and 99 individuals per generation. These results indicate high connectivity between the populations.
- Full Text:
- Date Issued: 2019
Early Jurassic dolerites of the Karoo Large Igneous Province ( KLIP): an analysis of their age and emplacement history from sea level to the Drakensberg Mountains in the Eastern Cape , South Africa Submitted
- Authors: Muedi, Thomas Tshifhiwa
- Date: 2019
- Subjects: Geological time , Geochemistry Geology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/41908 , vital:36608
- Description: South Africa hosts one of the largest Large Igneous Provinces (LIPs that is likely linked to the early separation of East and West Gondwana. However, despite many studies, the relationship between dolerites and volcanic basalts of this LIP (also known as the Karoo Large Igneous Province or KLIP) remains unsolved, because of poorly linked age dates (timing), geochemistry and emplacement mechanisms. This problem is in part because different unreliable dating techniques with large margin of errors have been applied This study aims to address these issues by performing new geo chemical and high resolution geochronological analyses on a number of dolerites (sills and dykes), volcanic s also referred to in the literature as the Drakensberg flood basalts) and samples from drill cores and field outcrops. This project is focused on dolerites in the Eastern Cape Province and provides results from field mapping of dolerites (sills and dykes) from the sea level to an elevation of circa 1350 metres above sea level (MASL) and their link to the volcanic in the Eastern Cape Province. The dolerite dykes observed trends from metres to hundreds of kilometres and cut across volcanic, which have similar geochemistry. The intrusive dolerites collected from the field and from d rill core samples were likely emplaced by magma infiltration through pre-existing sub vertical brittle fractures and fissures and then emplaced horizontally as sills circa 183 Ma Detailed fracture mapping across host rock to the dolerite was carried out to test if they acted as possible pathways for magmatic emplacements. The dolerite dykes and fractures mapped in the host sedimentary rocks have a dominant NW direction, especially towards volcanic basalts. The project provides tests based on the geochemical relationships of the dolerites and basalts from sixty-six (66) cores and field outcrop samples. The results confirm that the chemical analyses from the volcanic basalts an d dolerites are closely related and reveal that most samples are Ocean Island Basalt OIB), but some also reveal subduction related processes. This is consistent with models that suggest subduction along south west Gondwana may have influenced plumemagmatism derived from the lower mantle that initiated break up of this supercontinent e.g de Wit and Stern 1981 Storey et al , 1992 ; Torsvik et al., 2006 and Burke et al., 2008)
- Full Text:
- Date Issued: 2019
- Authors: Muedi, Thomas Tshifhiwa
- Date: 2019
- Subjects: Geological time , Geochemistry Geology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/41908 , vital:36608
- Description: South Africa hosts one of the largest Large Igneous Provinces (LIPs that is likely linked to the early separation of East and West Gondwana. However, despite many studies, the relationship between dolerites and volcanic basalts of this LIP (also known as the Karoo Large Igneous Province or KLIP) remains unsolved, because of poorly linked age dates (timing), geochemistry and emplacement mechanisms. This problem is in part because different unreliable dating techniques with large margin of errors have been applied This study aims to address these issues by performing new geo chemical and high resolution geochronological analyses on a number of dolerites (sills and dykes), volcanic s also referred to in the literature as the Drakensberg flood basalts) and samples from drill cores and field outcrops. This project is focused on dolerites in the Eastern Cape Province and provides results from field mapping of dolerites (sills and dykes) from the sea level to an elevation of circa 1350 metres above sea level (MASL) and their link to the volcanic in the Eastern Cape Province. The dolerite dykes observed trends from metres to hundreds of kilometres and cut across volcanic, which have similar geochemistry. The intrusive dolerites collected from the field and from d rill core samples were likely emplaced by magma infiltration through pre-existing sub vertical brittle fractures and fissures and then emplaced horizontally as sills circa 183 Ma Detailed fracture mapping across host rock to the dolerite was carried out to test if they acted as possible pathways for magmatic emplacements. The dolerite dykes and fractures mapped in the host sedimentary rocks have a dominant NW direction, especially towards volcanic basalts. The project provides tests based on the geochemical relationships of the dolerites and basalts from sixty-six (66) cores and field outcrop samples. The results confirm that the chemical analyses from the volcanic basalts an d dolerites are closely related and reveal that most samples are Ocean Island Basalt OIB), but some also reveal subduction related processes. This is consistent with models that suggest subduction along south west Gondwana may have influenced plumemagmatism derived from the lower mantle that initiated break up of this supercontinent e.g de Wit and Stern 1981 Storey et al , 1992 ; Torsvik et al., 2006 and Burke et al., 2008)
- Full Text:
- Date Issued: 2019
Ecological assessment and biogeography of coastal vegetation and flora in southern Mozambique
- Authors: Massingue, Alice Obed
- Date: 2019
- Subjects: Coastal plants -- Mozambique , Coastal plants Marine biodiversity -- Mozambique Coastal biodiversity -- Mozambique
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/40988 , vital:36280
- Description: This study considered aspects of the vegetation of the coastal zone of southern Mozambique, an area with a rich biodiversity. The vegetation and flora were assessed in their current state including the associated anthropogenic pressures. The environmental conditions that determined the distribution of the vegetation were evaluated. A hierarchical classification, description and ecological interpretation of the vegetation and flora of the coastal zone in southern Mozambique are presented. Analysis was based on 242 sample quadrats that were distributed in a stratified manner throughout the study area. The vegetation could be grouped into six distinct types of vegetation: Dune Forest, Coastal Forest, Coastal Grassland, Coastal Miombo, Coastal Savanna and Coastal Woodland. Species diversity was high for the all the vegetation types, particularly in the woody elements. A total of 673 species in 410 genera was recorded. They represented 104 families with Fabaceae and Rubiaceae being the most common. Of these, 6.6% were endemic or near-endemic to the coastal zone of southern Mozambique with Coastal Forest being the habitat with the greatest endemism. All soils from different vegetation types had poor agricultural potential. Soil properties were the strongest defining environmental feature separating the vegetation types: e.g. pH was high in Dune Forest compared to the others. Results from Maxent modelling suggest that the distribution of endemic species is influenced by a combination of climatic and non-climatic variables. Soil type, temperature annual range and precipitation of the driest month were the most important predictor variables. Overlaying the potential distributions of the seven selected species indicated two areas of abundance of endemic species – these should be given attention for conservation. Endemic species are not well protected in southern Mozambique – their sampled and potential habitats are largely outside protected areas. Hence, additional reserves should be created to improve their protection. Most endemic and near-endemics species were found in the south, from Ponta de Ouro (Matutuine, south of Maputo Province) to Manhica district (north of the Maputo Province) forming part of the Maputaland Centre of Endemism. A second concentration of endemism was found in the Inhambane Province, specifically the Inhassoro and Vilanculos districts. This is proposed to be an Important Plants Area (IPA). Because most endemics and near-endemics are found in the Coastal Forest, their main threat is harvesting for charcoal production, although none of the endemic species are specifically targeted for charcoal production. In Inhambane they are also threatened by the tourism industry, agriculture and settlements. The impact of the habitat destruction on endemic species is expected to cause severe declines in the near future. The tourism industry and harvesting of trees for charcoal production and over-frequent fires are the main drivers of vegetation loss in this region. Shifting agriculture, harvesting for firewood and construction materials, cattle grazing (at a minor scale) are also impacts, but these were only observed in a small area of Maputo Province. Although the study was done in coastal zone of southern Mozambique, effective management of whole coastal zone of the country will be required to maintain a functioning and diverse ecosystem. Priorities for management are to ensure that forests are protected, in particular, Dune Forest. Actions are required to minimise degradation of coastal vegetation. Further research on Coastal Forest restoration should be planned, as field observations in this study confirm that forest in the coastal zone of southern Mozambique has resilience.
- Full Text:
- Date Issued: 2019
- Authors: Massingue, Alice Obed
- Date: 2019
- Subjects: Coastal plants -- Mozambique , Coastal plants Marine biodiversity -- Mozambique Coastal biodiversity -- Mozambique
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/40988 , vital:36280
- Description: This study considered aspects of the vegetation of the coastal zone of southern Mozambique, an area with a rich biodiversity. The vegetation and flora were assessed in their current state including the associated anthropogenic pressures. The environmental conditions that determined the distribution of the vegetation were evaluated. A hierarchical classification, description and ecological interpretation of the vegetation and flora of the coastal zone in southern Mozambique are presented. Analysis was based on 242 sample quadrats that were distributed in a stratified manner throughout the study area. The vegetation could be grouped into six distinct types of vegetation: Dune Forest, Coastal Forest, Coastal Grassland, Coastal Miombo, Coastal Savanna and Coastal Woodland. Species diversity was high for the all the vegetation types, particularly in the woody elements. A total of 673 species in 410 genera was recorded. They represented 104 families with Fabaceae and Rubiaceae being the most common. Of these, 6.6% were endemic or near-endemic to the coastal zone of southern Mozambique with Coastal Forest being the habitat with the greatest endemism. All soils from different vegetation types had poor agricultural potential. Soil properties were the strongest defining environmental feature separating the vegetation types: e.g. pH was high in Dune Forest compared to the others. Results from Maxent modelling suggest that the distribution of endemic species is influenced by a combination of climatic and non-climatic variables. Soil type, temperature annual range and precipitation of the driest month were the most important predictor variables. Overlaying the potential distributions of the seven selected species indicated two areas of abundance of endemic species – these should be given attention for conservation. Endemic species are not well protected in southern Mozambique – their sampled and potential habitats are largely outside protected areas. Hence, additional reserves should be created to improve their protection. Most endemic and near-endemics species were found in the south, from Ponta de Ouro (Matutuine, south of Maputo Province) to Manhica district (north of the Maputo Province) forming part of the Maputaland Centre of Endemism. A second concentration of endemism was found in the Inhambane Province, specifically the Inhassoro and Vilanculos districts. This is proposed to be an Important Plants Area (IPA). Because most endemics and near-endemics are found in the Coastal Forest, their main threat is harvesting for charcoal production, although none of the endemic species are specifically targeted for charcoal production. In Inhambane they are also threatened by the tourism industry, agriculture and settlements. The impact of the habitat destruction on endemic species is expected to cause severe declines in the near future. The tourism industry and harvesting of trees for charcoal production and over-frequent fires are the main drivers of vegetation loss in this region. Shifting agriculture, harvesting for firewood and construction materials, cattle grazing (at a minor scale) are also impacts, but these were only observed in a small area of Maputo Province. Although the study was done in coastal zone of southern Mozambique, effective management of whole coastal zone of the country will be required to maintain a functioning and diverse ecosystem. Priorities for management are to ensure that forests are protected, in particular, Dune Forest. Actions are required to minimise degradation of coastal vegetation. Further research on Coastal Forest restoration should be planned, as field observations in this study confirm that forest in the coastal zone of southern Mozambique has resilience.
- Full Text:
- Date Issued: 2019
Effect of social capital and information acquisition on the adoption and benefits of conservation agriculture among cassava and maize smallholder farmers in South-West Nigeria
- Authors: Olawuyi, Seyi Olalekan
- Date: 2019
- Subjects: Agricultural conservation Sustainable agriculture Farms, Small|
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15200 , vital:40200
- Description: Sustainable economic growth and development in developing economy like Nigeria is achievable through the agricultural sector and sub-sectors which are concentrated in rural areas. Rural areas represent a home to majority (about 75%) of the households practicing farming for family sustenance and/or to earn income from the sales of agricultural products (Oyakhilomen and Zibah, 2014). In addition to the persistent use of traditional farming practices, these rural farming households cultivate crops varieties that are low-yielding on small and scattered farmland holdings (smallholder farmers) (Oyakhilomen and Zibah, 2014). This act depletes the soil organic matter with devastating consequences on production output, income generation as well as the ecosystem. Similarly, non-access to agricultural credit and limited technical knowhow are parts of the challenges that are facing the development of farming activities in subSaharan Africa, including Nigeria (Kassie, Pender, Yesuf, Köhlin, Bluffstone and Mulugeta, 2008). These challenges call for holistic interventions such as conservative agricultural practices; which are sustainable, promote safe environment and ultimately increase production output.
- Full Text:
- Date Issued: 2019
- Authors: Olawuyi, Seyi Olalekan
- Date: 2019
- Subjects: Agricultural conservation Sustainable agriculture Farms, Small|
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15200 , vital:40200
- Description: Sustainable economic growth and development in developing economy like Nigeria is achievable through the agricultural sector and sub-sectors which are concentrated in rural areas. Rural areas represent a home to majority (about 75%) of the households practicing farming for family sustenance and/or to earn income from the sales of agricultural products (Oyakhilomen and Zibah, 2014). In addition to the persistent use of traditional farming practices, these rural farming households cultivate crops varieties that are low-yielding on small and scattered farmland holdings (smallholder farmers) (Oyakhilomen and Zibah, 2014). This act depletes the soil organic matter with devastating consequences on production output, income generation as well as the ecosystem. Similarly, non-access to agricultural credit and limited technical knowhow are parts of the challenges that are facing the development of farming activities in subSaharan Africa, including Nigeria (Kassie, Pender, Yesuf, Köhlin, Bluffstone and Mulugeta, 2008). These challenges call for holistic interventions such as conservative agricultural practices; which are sustainable, promote safe environment and ultimately increase production output.
- Full Text:
- Date Issued: 2019
Effects of pre-slaughter stress, sex and breed on blood stress indicators, heat shock proteins, glycolytic potential and lamb quality
- Authors: Stempa ,Thuthuzelwa
- Date: 2019
- Subjects: Animal welfare Meat--Quality
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15376 , vital:40402
- Description: The main objective of this study was to determine the effects of pre-slaughter stress (transportation distance and lairage duration), sex and breed on blood stress indicators, heat shock proteins, post-mortem muscle metabolites (glycogen, glucose, glucose-6-phosphate and lactate), glycolytic potential and meat quality attributes from lambs slaughtered at a commercial abattoir. The study was conducted in a high-throughput commercial abattoir in the Buffalo City local municipality of the Eastern Cape Province, South Africa. A total of a hundred eight-month old Dorper and Merino lambs, both male and female, were used in the study. Blood samples for the analysis of glucose and lactate levels were collected using 10.0 mL disposable Becton Dickinson vacutainer tubes treated with fluoride oxalate (grey top) whereas those for determination of cortisol and heat shock protein 70 (HSPA1A) levels were collected using plasma separating vacutainer tubes (SSTTMII, gold top), and those for analysis of creatine kinase and lactate dehydrogenase were collected using 10.0 ml vacutainer tubes treated with Ethylenediaminetetraacetic acid (EDTA). Meat samples (~50 g) for the measurement of post-mortem energy metabolites (glycogen, lactate glucose-6-phosphate and glucose content) were collected from the Muscularis longimissius thoracis et lumborum (LTL) of each carcass ~30 minutes after slaughter and immediately frozen in liquid nitrogen (-196 oC) to prevent further glycolysis. Cold carcass weight (CCW), warm carcass weight (WCW) and carcass fatness (CF) was measured. Meat pH and temperature were measured at iii 45 minutes (initial pH), 6 hours and 24 hours ultimate pH (pHu) post-mortem. Meat colour coordinates [lightness (L*), redness (a*), yellowness (b*), hue angle (H*), chroma (C*)] were also measured 24 hours after slaughter. Furthermore, thawing loss (TL%), cooking loss (CL%) and warner braztler shear force (WBSF) was measured in the LTL 7 days post slaughter. Breed had a significant effect on plasma HSPA1A, plasma lactate, WCW, CCW, L*, muscle glycogen and WBSF. Sex had a significant effect on plasma HSPA1A and pHu. Pearson‘s correlations showed that meat muscle glycogen was positively correlated to glycolytic potential (P<0.001; r=0.63) and initial pH (P<0.05, r=0.20). Muscle lactate was positively correlated to muscle glucose (P<0.01, r=0.30) and glycolytic potential (P<0.001, r=0.79). A positive correlation was shown between muscle glucose and glycolytic potential (P<0.05, r=0.23). The level of LDH was affected by the distance travelled by lambs prior to slaughter. Lairage duration did not affect the levels of CK and LDH. Principal Component Analysis showed a relationship between distance travelled and CK and LDH; and that CK and LDH also influenced the quality of meat from lambs. With respect to sex and breed, the results indicate that female and Dorper were more stressed than male and Merino respectively. Muscle glycolytic potential and post-mortem metabolites have an impact on the quality of meat produced and the Merino had higher muscle glycogen levels at slaughter; hence they produced better meat quality compared to the Dorper. Moreover, no associations were seen between pHu and blood stress indicators. These results indicate that blood stress indicators at exsanguination cannot be used as useful indicators of dark cutting condition in lamb. A relationship between pHu, muscle glycogen and glycolytic potential was established and thus meat pHu can be used as a reliable indicator of tenderness in lamb.
- Full Text:
- Date Issued: 2019
- Authors: Stempa ,Thuthuzelwa
- Date: 2019
- Subjects: Animal welfare Meat--Quality
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15376 , vital:40402
- Description: The main objective of this study was to determine the effects of pre-slaughter stress (transportation distance and lairage duration), sex and breed on blood stress indicators, heat shock proteins, post-mortem muscle metabolites (glycogen, glucose, glucose-6-phosphate and lactate), glycolytic potential and meat quality attributes from lambs slaughtered at a commercial abattoir. The study was conducted in a high-throughput commercial abattoir in the Buffalo City local municipality of the Eastern Cape Province, South Africa. A total of a hundred eight-month old Dorper and Merino lambs, both male and female, were used in the study. Blood samples for the analysis of glucose and lactate levels were collected using 10.0 mL disposable Becton Dickinson vacutainer tubes treated with fluoride oxalate (grey top) whereas those for determination of cortisol and heat shock protein 70 (HSPA1A) levels were collected using plasma separating vacutainer tubes (SSTTMII, gold top), and those for analysis of creatine kinase and lactate dehydrogenase were collected using 10.0 ml vacutainer tubes treated with Ethylenediaminetetraacetic acid (EDTA). Meat samples (~50 g) for the measurement of post-mortem energy metabolites (glycogen, lactate glucose-6-phosphate and glucose content) were collected from the Muscularis longimissius thoracis et lumborum (LTL) of each carcass ~30 minutes after slaughter and immediately frozen in liquid nitrogen (-196 oC) to prevent further glycolysis. Cold carcass weight (CCW), warm carcass weight (WCW) and carcass fatness (CF) was measured. Meat pH and temperature were measured at iii 45 minutes (initial pH), 6 hours and 24 hours ultimate pH (pHu) post-mortem. Meat colour coordinates [lightness (L*), redness (a*), yellowness (b*), hue angle (H*), chroma (C*)] were also measured 24 hours after slaughter. Furthermore, thawing loss (TL%), cooking loss (CL%) and warner braztler shear force (WBSF) was measured in the LTL 7 days post slaughter. Breed had a significant effect on plasma HSPA1A, plasma lactate, WCW, CCW, L*, muscle glycogen and WBSF. Sex had a significant effect on plasma HSPA1A and pHu. Pearson‘s correlations showed that meat muscle glycogen was positively correlated to glycolytic potential (P<0.001; r=0.63) and initial pH (P<0.05, r=0.20). Muscle lactate was positively correlated to muscle glucose (P<0.01, r=0.30) and glycolytic potential (P<0.001, r=0.79). A positive correlation was shown between muscle glucose and glycolytic potential (P<0.05, r=0.23). The level of LDH was affected by the distance travelled by lambs prior to slaughter. Lairage duration did not affect the levels of CK and LDH. Principal Component Analysis showed a relationship between distance travelled and CK and LDH; and that CK and LDH also influenced the quality of meat from lambs. With respect to sex and breed, the results indicate that female and Dorper were more stressed than male and Merino respectively. Muscle glycolytic potential and post-mortem metabolites have an impact on the quality of meat produced and the Merino had higher muscle glycogen levels at slaughter; hence they produced better meat quality compared to the Dorper. Moreover, no associations were seen between pHu and blood stress indicators. These results indicate that blood stress indicators at exsanguination cannot be used as useful indicators of dark cutting condition in lamb. A relationship between pHu, muscle glycogen and glycolytic potential was established and thus meat pHu can be used as a reliable indicator of tenderness in lamb.
- Full Text:
- Date Issued: 2019
Elasticity of the South African economy towards portfolio investments in BRICS countries
- Authors: Taonezvi, Lovemore
- Date: 2019
- Subjects: Economic development -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/44537 , vital:38141
- Description: The emerging economies of Brazil, Russia, India, and China (BRIC) have been experiencing high growth rates since the turn of the millennium, whereas economic growth has been elusive in South Africa. As the newest member of BRICS, South Africa is expected to economically benefit through, amongst others, increases in capital flows, foreign investments by local firms, and increases in trade. Such benefits are anticipated to propel the country’s economic growth, thereby helping it to tackle its chronic problems of high unemployment, poverty, and economic inequality. The inclusion of South Africa in BRICS has, however, been viewed by critics as erroneous, since the country has, inter alia, poor economic growth; a small economy and population; and political instability. While foreign portfolio investment (FPI) inflows to South Africa have surged in recent years, economic growth has remained lacklustre. These flows have also faced sudden reversals, especially during the financial crisis of 2007-2009. With the potential to leverage its growth from intra-BRICS FPI inflows, it becomes of paramount significance for policymakers to have knowledge of the South African economy’s responsiveness to such inflows. With a theoretical framework based on the endogenous growth model, an augmented Cobb-Douglas production function was extended in this thesis in order to study the relationship between BRICS growth and intra-BRICS FPI in a dynamic panel data generalised method of moments (GMM) context. Similarly, the South African economy’s elasticity towards intraBRICS FPI was estimated. Vector autoregressive (VAR) analysis was used to evaluate the responsiveness of South Africa’s economy to an innovative shock to intra-BRICS FPI. Annual and quarterly data for the period 2000-2016 were used in panel data and VAR analysis, respectively. It was found that intra-BRICS FPI flows have a positive and statistically significant relationship with BRICS growth, while the elasticity of the South African economy to these flows is estimated at 0.007. Additionally, the efficiency and accessibility dimensions of financial market development do not assist FPI in promoting growth in BRICS, while financial market depth does. South Africa’s BRICS membership has a positive effect on its own growth, while for other BRICS nations, this membership is negative and insignificant. Credit rating downgrades have a negative and insignificant impact on economic growth, while the negative impact for inflation, government expenditure, and total labour employment is significant. Conversely, gross capital formation and trade openness have a positive and significant relationship with BRICS growth. The study also determined that a unit shock on intra-BRICS FPI resulted in negative fluctuations of South Africa’s economy within the first eight quarters before being positive and mostly constant thereafter. By supplementing domestic savings and facilitating the international integration of domestic financial markets, FPI promotes growth in BRICS. The short-term, ease of reversibility, and speculative nature of FPI are amongst some of the reasons for its destabilising effect on South Africa’s economy. Furthermore, inflation is a key determinant of FPI inflows to South Africa. Additional BRIC cooperation in FPI and trade; increased investments in domestic capital; reductions of inflation and corruption; investments in education and skills development; and stock market reforms are some of the recommendations for BRIC, and South Africa in particular. South Africa can consider prudential use of a mix of capital account controls, as well as fiscal and monetary policies to cushion its economy from FPI shocks in the short- to medium-term.
- Full Text:
- Date Issued: 2019
- Authors: Taonezvi, Lovemore
- Date: 2019
- Subjects: Economic development -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/44537 , vital:38141
- Description: The emerging economies of Brazil, Russia, India, and China (BRIC) have been experiencing high growth rates since the turn of the millennium, whereas economic growth has been elusive in South Africa. As the newest member of BRICS, South Africa is expected to economically benefit through, amongst others, increases in capital flows, foreign investments by local firms, and increases in trade. Such benefits are anticipated to propel the country’s economic growth, thereby helping it to tackle its chronic problems of high unemployment, poverty, and economic inequality. The inclusion of South Africa in BRICS has, however, been viewed by critics as erroneous, since the country has, inter alia, poor economic growth; a small economy and population; and political instability. While foreign portfolio investment (FPI) inflows to South Africa have surged in recent years, economic growth has remained lacklustre. These flows have also faced sudden reversals, especially during the financial crisis of 2007-2009. With the potential to leverage its growth from intra-BRICS FPI inflows, it becomes of paramount significance for policymakers to have knowledge of the South African economy’s responsiveness to such inflows. With a theoretical framework based on the endogenous growth model, an augmented Cobb-Douglas production function was extended in this thesis in order to study the relationship between BRICS growth and intra-BRICS FPI in a dynamic panel data generalised method of moments (GMM) context. Similarly, the South African economy’s elasticity towards intraBRICS FPI was estimated. Vector autoregressive (VAR) analysis was used to evaluate the responsiveness of South Africa’s economy to an innovative shock to intra-BRICS FPI. Annual and quarterly data for the period 2000-2016 were used in panel data and VAR analysis, respectively. It was found that intra-BRICS FPI flows have a positive and statistically significant relationship with BRICS growth, while the elasticity of the South African economy to these flows is estimated at 0.007. Additionally, the efficiency and accessibility dimensions of financial market development do not assist FPI in promoting growth in BRICS, while financial market depth does. South Africa’s BRICS membership has a positive effect on its own growth, while for other BRICS nations, this membership is negative and insignificant. Credit rating downgrades have a negative and insignificant impact on economic growth, while the negative impact for inflation, government expenditure, and total labour employment is significant. Conversely, gross capital formation and trade openness have a positive and significant relationship with BRICS growth. The study also determined that a unit shock on intra-BRICS FPI resulted in negative fluctuations of South Africa’s economy within the first eight quarters before being positive and mostly constant thereafter. By supplementing domestic savings and facilitating the international integration of domestic financial markets, FPI promotes growth in BRICS. The short-term, ease of reversibility, and speculative nature of FPI are amongst some of the reasons for its destabilising effect on South Africa’s economy. Furthermore, inflation is a key determinant of FPI inflows to South Africa. Additional BRIC cooperation in FPI and trade; increased investments in domestic capital; reductions of inflation and corruption; investments in education and skills development; and stock market reforms are some of the recommendations for BRIC, and South Africa in particular. South Africa can consider prudential use of a mix of capital account controls, as well as fiscal and monetary policies to cushion its economy from FPI shocks in the short- to medium-term.
- Full Text:
- Date Issued: 2019
Electrical, photo-thermal and mechanical degradation analysis of degraded single junction amorphous silicon solar modules
- Osayemwenre, Gilbert Omorodion
- Authors: Osayemwenre, Gilbert Omorodion
- Date: 2019
- Subjects: Solar cells Amorphous semiconductors Silicon
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15211 , vital:40204
- Description: In this present era of sustainable energy development, photovoltaic modules which are based on amorphous silicon cells have immeasurable prospects of contributing meaningfully to the energy demand of the world at large. The global consciousness of environmental safety issues has birthed the rapid demand for the photovoltaic system. However, the production increase is mainly in bulk-type crystalline (c-Si) solar cells. Thus, to meet the high demand of the market, single junction amorphous silicon (a-Si:H) solar cells production must be encouraged through active research in that regard. This could also help to improve its efficiency and reliability. There has recently been a sharp decrease in the production cost of the bulk Si solar cell, but the a-Si:H solar cell still remains the most economically viable in comparison to the other PV technologies. Companies such as Sharp are currently developing large-scale a-Si:H solar modules that can produce an efficiency of 10.5% after the long-term degradation process. To date, a-Si:H is believed to be one of the most promising thin-film PV technologies (Saito et al., 1993; Hamakawa et al., 1994). The cost of a solar PV manufacturing fell by 6% in 2014 (Santa, 2014), this is in accordance with the 2008 cost production forecast; thus, the cost record stands at 0.20 per watt, as reported by the NPD Solar publisher. Amorphous silicon (a-Si) solar modules generate more kilowatt-hour (kWh) of electricity per kilowatt (kW) than crystalline silicon or other technologies of the same capacity of installation. Furthermore, a-Si:H modules have more functional hours per day. Single junction amorphous silicon (a-Si:H) modules can function beyond the peak sun hours, and they also have a better performance on a cloudy day. vii In other words, a 1kW PV system of a-Si:H is expected to generate more electricity per year in comparison to 1kW PV from other technologies, hence there is a low energy payback time. In this study, commercially available single junction amorphous silicon modules were bought from a local market and they were immediately deployed outdoors. The initial reading of the modules, which served as baseline reading, showed an average of 25% decrease in the modules performance, therefore, there is a need for a long term monitoring process to obtain the best and worst performing modules. Measuring the performance parameters of these PV modules under real sun light (IV) provides a better degradation assessment. This conventional assessment cannot provide an in-depth insight responsible for the variation and degradation of the performance parameters. More obscured parameters like recombination current and ideality factor were obtained from the dark IV measurements. However, this is still superficial in a way. The intrinsic parameters were obtained from scanning probe microscopy (SPM) and CV measurements. The study focuses on the degradation analysis of a-Si:H due to an increase in defect density. A rise in the defect concentration is a huge problem because it causes long-term solar cell degradation, which increases the recombination current and decreases the conversion efficiency. Furthermore, it decreases the photo-generating current and reduces the effective efficiency of the solar device. In other words, the electrical output decreases. This research investigates the reduction in a-Si:H modules’ maximum power, and correlates these with a hot spot formation. A PVPM IV tracer was used for the outdoor characterisation of the module’s temperature profile, while the IR camera was used to analyse the hot spot centre. A four probe IV/CV from NMU was used for the indoor assessment of smaller samples cleaved from both the affected and non-affected regions to characterise the electrical variations across the module viii samples. To be precise, in this study, a naturally degraded single junction amorphous silicon module was delaminated and its mechanical properties were analysed and correlated with the contact potential from a Kelvin probe force microscopy (KPFM).
- Full Text:
- Date Issued: 2019
- Authors: Osayemwenre, Gilbert Omorodion
- Date: 2019
- Subjects: Solar cells Amorphous semiconductors Silicon
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15211 , vital:40204
- Description: In this present era of sustainable energy development, photovoltaic modules which are based on amorphous silicon cells have immeasurable prospects of contributing meaningfully to the energy demand of the world at large. The global consciousness of environmental safety issues has birthed the rapid demand for the photovoltaic system. However, the production increase is mainly in bulk-type crystalline (c-Si) solar cells. Thus, to meet the high demand of the market, single junction amorphous silicon (a-Si:H) solar cells production must be encouraged through active research in that regard. This could also help to improve its efficiency and reliability. There has recently been a sharp decrease in the production cost of the bulk Si solar cell, but the a-Si:H solar cell still remains the most economically viable in comparison to the other PV technologies. Companies such as Sharp are currently developing large-scale a-Si:H solar modules that can produce an efficiency of 10.5% after the long-term degradation process. To date, a-Si:H is believed to be one of the most promising thin-film PV technologies (Saito et al., 1993; Hamakawa et al., 1994). The cost of a solar PV manufacturing fell by 6% in 2014 (Santa, 2014), this is in accordance with the 2008 cost production forecast; thus, the cost record stands at 0.20 per watt, as reported by the NPD Solar publisher. Amorphous silicon (a-Si) solar modules generate more kilowatt-hour (kWh) of electricity per kilowatt (kW) than crystalline silicon or other technologies of the same capacity of installation. Furthermore, a-Si:H modules have more functional hours per day. Single junction amorphous silicon (a-Si:H) modules can function beyond the peak sun hours, and they also have a better performance on a cloudy day. vii In other words, a 1kW PV system of a-Si:H is expected to generate more electricity per year in comparison to 1kW PV from other technologies, hence there is a low energy payback time. In this study, commercially available single junction amorphous silicon modules were bought from a local market and they were immediately deployed outdoors. The initial reading of the modules, which served as baseline reading, showed an average of 25% decrease in the modules performance, therefore, there is a need for a long term monitoring process to obtain the best and worst performing modules. Measuring the performance parameters of these PV modules under real sun light (IV) provides a better degradation assessment. This conventional assessment cannot provide an in-depth insight responsible for the variation and degradation of the performance parameters. More obscured parameters like recombination current and ideality factor were obtained from the dark IV measurements. However, this is still superficial in a way. The intrinsic parameters were obtained from scanning probe microscopy (SPM) and CV measurements. The study focuses on the degradation analysis of a-Si:H due to an increase in defect density. A rise in the defect concentration is a huge problem because it causes long-term solar cell degradation, which increases the recombination current and decreases the conversion efficiency. Furthermore, it decreases the photo-generating current and reduces the effective efficiency of the solar device. In other words, the electrical output decreases. This research investigates the reduction in a-Si:H modules’ maximum power, and correlates these with a hot spot formation. A PVPM IV tracer was used for the outdoor characterisation of the module’s temperature profile, while the IR camera was used to analyse the hot spot centre. A four probe IV/CV from NMU was used for the indoor assessment of smaller samples cleaved from both the affected and non-affected regions to characterise the electrical variations across the module viii samples. To be precise, in this study, a naturally degraded single junction amorphous silicon module was delaminated and its mechanical properties were analysed and correlated with the contact potential from a Kelvin probe force microscopy (KPFM).
- Full Text:
- Date Issued: 2019
Elucidating the Molecular Basis of the Interaction between the β2-integrin, αXβ2, and the low-affinity IgE Receptor, CD23
- Authors: Clarke, Stephen
- Date: 2019
- Subjects: CD23 antigen , Immune response Cellular immunity Molecular immunology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/37990 , vital:34277
- Description: The low affinity IgE receptor, CD23, is involved in a myriad of immune reactions. It is not only a receptor for IgE, but also functions in the regulation of IgE synthesis, isotype switching in B cells, and induction of the inflammatory response. These effector functions of CD23 arise through its interaction with another leukocyte-specific cell surface receptor – the β2 integrin subfamily. However, this interaction has not been fully described. It has been shown that CD23 is capable of interacting with the β3 and β5 integrin β-subunit of integrins via a basic RKC motif in a metal cation-independent fashion. The currently proposed mechanism for the interaction between CD23 and the integrin superfamily was applied to the β2 integrin subfamily. In this study the interaction was probed for whether or not the RKC motif governs the interaction as well. This was done by performing bioinformatics docking predictions between the CD23 and αXβ2 integrin proteins. This revealed that in the absence of cations, the RKC motif is involved in interaction with the integrin αI domain. However, since physiologically integrin activity has been shown to be regulated by metal cations, docking predictions were also performed in the presence of such cations. This showed the interaction to involve novel acidic motifs within the CD23 protein, GEF and LDL. This same pattern of interaction was seen in docking predictions between CD23 and the β2- and β3I-like domains. To further investigate, recombinant proteins of sCD23 and the αXI domain were produced using E. coli expression systems. The DNA sequence was mutated to produce mutant versions of the CD23 RKC and GEF motifs as well as a high-affinity locked αXI domain. These proteins were used in subsequent SPR spectroscopy analysis of the binding affinity between immobilised integrin and CD23 analyte. It was shown that the mutation within the RKC motif reduced the binding affinity under cation-independence, especially when the Arg172 residue was substituted. However binding was not completely lost. This result was supported by synthetic peptides containing the same RKC motif and substitutions. These showed complete loss in binding in the double RKΔAA substitution, suggesting the involvement of other residues in the RKC-dependent interaction. In contrast, under cation dependence, the RKC motif substitutions showed no effect on binding affinity, while the GEF motif substitution exhibited near complete loss in binding. This same effect on binding was validated by U937 cell-based ELISA using live cells. This showed decreased capture of differentiated U937 cells, expressing the αXβ2 integrin, by immobilised recombinant sCD23 protein. In this study it was noted that, 2 contrary to the SPR analysis, metal cations allowed for a higher titre of cells to be captured in comparison to the cation-free binding.
- Full Text:
- Date Issued: 2019
- Authors: Clarke, Stephen
- Date: 2019
- Subjects: CD23 antigen , Immune response Cellular immunity Molecular immunology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/37990 , vital:34277
- Description: The low affinity IgE receptor, CD23, is involved in a myriad of immune reactions. It is not only a receptor for IgE, but also functions in the regulation of IgE synthesis, isotype switching in B cells, and induction of the inflammatory response. These effector functions of CD23 arise through its interaction with another leukocyte-specific cell surface receptor – the β2 integrin subfamily. However, this interaction has not been fully described. It has been shown that CD23 is capable of interacting with the β3 and β5 integrin β-subunit of integrins via a basic RKC motif in a metal cation-independent fashion. The currently proposed mechanism for the interaction between CD23 and the integrin superfamily was applied to the β2 integrin subfamily. In this study the interaction was probed for whether or not the RKC motif governs the interaction as well. This was done by performing bioinformatics docking predictions between the CD23 and αXβ2 integrin proteins. This revealed that in the absence of cations, the RKC motif is involved in interaction with the integrin αI domain. However, since physiologically integrin activity has been shown to be regulated by metal cations, docking predictions were also performed in the presence of such cations. This showed the interaction to involve novel acidic motifs within the CD23 protein, GEF and LDL. This same pattern of interaction was seen in docking predictions between CD23 and the β2- and β3I-like domains. To further investigate, recombinant proteins of sCD23 and the αXI domain were produced using E. coli expression systems. The DNA sequence was mutated to produce mutant versions of the CD23 RKC and GEF motifs as well as a high-affinity locked αXI domain. These proteins were used in subsequent SPR spectroscopy analysis of the binding affinity between immobilised integrin and CD23 analyte. It was shown that the mutation within the RKC motif reduced the binding affinity under cation-independence, especially when the Arg172 residue was substituted. However binding was not completely lost. This result was supported by synthetic peptides containing the same RKC motif and substitutions. These showed complete loss in binding in the double RKΔAA substitution, suggesting the involvement of other residues in the RKC-dependent interaction. In contrast, under cation dependence, the RKC motif substitutions showed no effect on binding affinity, while the GEF motif substitution exhibited near complete loss in binding. This same effect on binding was validated by U937 cell-based ELISA using live cells. This showed decreased capture of differentiated U937 cells, expressing the αXβ2 integrin, by immobilised recombinant sCD23 protein. In this study it was noted that, 2 contrary to the SPR analysis, metal cations allowed for a higher titre of cells to be captured in comparison to the cation-free binding.
- Full Text:
- Date Issued: 2019
Employee talent management in the Uganda health sector: a public institutions perspective
- Authors: Nakato, Jamidah
- Date: 2019
- Subjects: Employee retention -- Uganda , Leadership -- Uganda Executives -- Training of Executive ability
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/41751 , vital:36578
- Description: Globally, talent management has been acknowledged as a prime source of employee attraction and retention as well as organisational performance and commitment. Although the health sector plays an important role in the economic development of any country, in Uganda, the management of talented employees still remains a challenge. In this country, many institutions have not incorporated and adopted suitable talent management strategies, thus compromising access to and quality of care. A hypothetical model and measuring instruments were developed to investigate the factors contributing to and the benefits of effective employee talent management in the Ugandan health sector. The following ten independent variables that have the prospect of influencing effective talent management (intervening variable) were identified on the basis of organisational, management and personal factors: talent pool, organisational support, work conditions, social and work environment, reward system, leadership styles, career development, supervisor support, employee engagement and employee personality. In this study, it was also postulated that talent management has potential to effect the dependent variables, namely, talent attraction, employee retention, organisational performance and organisational commitment. In total, fourteen hypotheses were formulated to test relationships between independent, intervening and dependent variables. The study utilised the quantitative research paradigm in order to seek employee perceptions regarding public institutions within the health sector, in Uganda’s Central region. Using stratified random sampling, a sample of 910 participants was drawn from the identified population. A survey was conducted with the aid of a structured, selfadministered questionnaire that was distributed to the seven categories of hospitals and health centres in Central Uganda; 910 questionnaires were distributed to doctors, consultants, dentists, dispensers, nurses, pharmacists, clinical officers, laboratory staff, occupational therapists, allied health staff, environmental health officers, general administrative cadres, cold chain technicians and support staff. Of these, 655 were useable, which indicates a 71% response rate. The data collected was captured and analysed using various statistical analysis techniques. The study findings reveal that organisational support, employee satisfaction, an enabling work environment, a stable working environment and career development effectively influence talent management. However, management in health sector institutions need to realise the importance of facilitating and monitoring job autonomy and personal values in order to effectively enhance talent management. The study results further reveal that talent management has a positive influence on employee retention and holistic development for organisational performance. For optimal talent management, the study recommends that organisations pay attention to cultivating an enabling and stable work environment that is suitable for motivating employees towards improved performance and work commitment. Therefore, health sector management should focus on potential, and not only on performance, by matching individuals with the right positions that can expose their capabilities and potential. It was further recommended that organisations need to accept and show confidence in their employees by allowing them freedom in carrying out their tasks. In addition, it was highlighted that ascertaining and utilising information about the values and principles that employees hold can help explain their behaviours and attitudes at work. This would increase the chances of talented employees realising their full potential and competencies in their jobs. Therefore, this study found that there is a need for public institutions within the health sector to focus on supporting employees by offering a well-defined career development programme, which caters for the needs of individuals and which acts as an incentive for the recruitment of qualified employees. Thus, management will succeed in retaining, attracting and maintaining talented individuals who can perform well. In order to uphold the expected ethical behaviour of conducting research, the researcher obtained approval and ethics clearance from Nelson Mandela University, permission to conduct the study from the Ugandan Ministry of Health, and communicated all the information relevant to the study to the participants.
- Full Text:
- Date Issued: 2019
- Authors: Nakato, Jamidah
- Date: 2019
- Subjects: Employee retention -- Uganda , Leadership -- Uganda Executives -- Training of Executive ability
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/41751 , vital:36578
- Description: Globally, talent management has been acknowledged as a prime source of employee attraction and retention as well as organisational performance and commitment. Although the health sector plays an important role in the economic development of any country, in Uganda, the management of talented employees still remains a challenge. In this country, many institutions have not incorporated and adopted suitable talent management strategies, thus compromising access to and quality of care. A hypothetical model and measuring instruments were developed to investigate the factors contributing to and the benefits of effective employee talent management in the Ugandan health sector. The following ten independent variables that have the prospect of influencing effective talent management (intervening variable) were identified on the basis of organisational, management and personal factors: talent pool, organisational support, work conditions, social and work environment, reward system, leadership styles, career development, supervisor support, employee engagement and employee personality. In this study, it was also postulated that talent management has potential to effect the dependent variables, namely, talent attraction, employee retention, organisational performance and organisational commitment. In total, fourteen hypotheses were formulated to test relationships between independent, intervening and dependent variables. The study utilised the quantitative research paradigm in order to seek employee perceptions regarding public institutions within the health sector, in Uganda’s Central region. Using stratified random sampling, a sample of 910 participants was drawn from the identified population. A survey was conducted with the aid of a structured, selfadministered questionnaire that was distributed to the seven categories of hospitals and health centres in Central Uganda; 910 questionnaires were distributed to doctors, consultants, dentists, dispensers, nurses, pharmacists, clinical officers, laboratory staff, occupational therapists, allied health staff, environmental health officers, general administrative cadres, cold chain technicians and support staff. Of these, 655 were useable, which indicates a 71% response rate. The data collected was captured and analysed using various statistical analysis techniques. The study findings reveal that organisational support, employee satisfaction, an enabling work environment, a stable working environment and career development effectively influence talent management. However, management in health sector institutions need to realise the importance of facilitating and monitoring job autonomy and personal values in order to effectively enhance talent management. The study results further reveal that talent management has a positive influence on employee retention and holistic development for organisational performance. For optimal talent management, the study recommends that organisations pay attention to cultivating an enabling and stable work environment that is suitable for motivating employees towards improved performance and work commitment. Therefore, health sector management should focus on potential, and not only on performance, by matching individuals with the right positions that can expose their capabilities and potential. It was further recommended that organisations need to accept and show confidence in their employees by allowing them freedom in carrying out their tasks. In addition, it was highlighted that ascertaining and utilising information about the values and principles that employees hold can help explain their behaviours and attitudes at work. This would increase the chances of talented employees realising their full potential and competencies in their jobs. Therefore, this study found that there is a need for public institutions within the health sector to focus on supporting employees by offering a well-defined career development programme, which caters for the needs of individuals and which acts as an incentive for the recruitment of qualified employees. Thus, management will succeed in retaining, attracting and maintaining talented individuals who can perform well. In order to uphold the expected ethical behaviour of conducting research, the researcher obtained approval and ethics clearance from Nelson Mandela University, permission to conduct the study from the Ugandan Ministry of Health, and communicated all the information relevant to the study to the participants.
- Full Text:
- Date Issued: 2019
Energy yield modelling and analysis of photovoltaic systems in Namibia
- Authors: Dobreva, Petja
- Date: 2019
- Subjects: Photovoltaic power systems , Photovoltaic power generation Photovoltaic power generation -- Mathematical models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/39523 , vital:35287
- Description: Generation of electricity from solar energy by photovoltaic systems has the potential to reduce dependence on non-renewable sources for electrical energy production. It can also reduce the cost of electricity for consumers by moving away from the traditional models of centralised generation combined with extensive transmission. The prices of photovoltaic system components have decreased so dramatically in recent years that nowadays a large portion of the cost of electricity produced by photovoltaic systems is due to the cost of investment capital rather than the cost of the physical parts of the system. The cost of capital is determined by the perceived risk of the investment and is contingent on predictive models whose aim is to project outputs reasonably achievable by the system. The output of a photovoltaic system depends strongly on external factors, like solar radiation and temperature, as well as internal, system specific factors. Models that can accurately predict the output of a photovoltaic system have direct impact on investment cost. Several measures, like root-mean-square-error or coincident of determination, have been used in the past to assess accuracy of models but they appear to be inadequate for the task. I suggest a new method, comprising qualitative and quantitative measures, for model evaluation and introduce two new quantities to assess the predictive capabilities of the models. Models of several photovoltaic systems in Namibia were created, the new evaluation approach was applied to them and the results were compared to the conclusions that would have been drawn if the old measures were used. Outdoor current-voltage measurements are used to assess the power output and general state of the solar generator of a photovoltaic system, but the measured values strongly depend on irradiance and temperature. The prevailing approach has been to transform the current-voltage characteristics to standard-test-conditions with the so-called translation equations and then compare the translated power to the nominal value. The translated value of the power, however, depends on the translation equations used and is not necessarily an accurate reaction of the state of the solar generator. I have proposed a new method for assessment of the state of the solar generator that relies only on the measured quantities and does not require translations to standard-test-conditions. This alternative method has been used in the assessment of the condition of the solar generators in the systems included in this study.
- Full Text:
- Date Issued: 2019
- Authors: Dobreva, Petja
- Date: 2019
- Subjects: Photovoltaic power systems , Photovoltaic power generation Photovoltaic power generation -- Mathematical models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/39523 , vital:35287
- Description: Generation of electricity from solar energy by photovoltaic systems has the potential to reduce dependence on non-renewable sources for electrical energy production. It can also reduce the cost of electricity for consumers by moving away from the traditional models of centralised generation combined with extensive transmission. The prices of photovoltaic system components have decreased so dramatically in recent years that nowadays a large portion of the cost of electricity produced by photovoltaic systems is due to the cost of investment capital rather than the cost of the physical parts of the system. The cost of capital is determined by the perceived risk of the investment and is contingent on predictive models whose aim is to project outputs reasonably achievable by the system. The output of a photovoltaic system depends strongly on external factors, like solar radiation and temperature, as well as internal, system specific factors. Models that can accurately predict the output of a photovoltaic system have direct impact on investment cost. Several measures, like root-mean-square-error or coincident of determination, have been used in the past to assess accuracy of models but they appear to be inadequate for the task. I suggest a new method, comprising qualitative and quantitative measures, for model evaluation and introduce two new quantities to assess the predictive capabilities of the models. Models of several photovoltaic systems in Namibia were created, the new evaluation approach was applied to them and the results were compared to the conclusions that would have been drawn if the old measures were used. Outdoor current-voltage measurements are used to assess the power output and general state of the solar generator of a photovoltaic system, but the measured values strongly depend on irradiance and temperature. The prevailing approach has been to transform the current-voltage characteristics to standard-test-conditions with the so-called translation equations and then compare the translated power to the nominal value. The translated value of the power, however, depends on the translation equations used and is not necessarily an accurate reaction of the state of the solar generator. I have proposed a new method for assessment of the state of the solar generator that relies only on the measured quantities and does not require translations to standard-test-conditions. This alternative method has been used in the assessment of the condition of the solar generators in the systems included in this study.
- Full Text:
- Date Issued: 2019
Enumeration, conformation sampling and population of libraries of peptide macrocycles for the search of chemotherapeutic cardioprotection agents
- Authors: Sigauke, Lester Takunda
- Date: 2019
- Subjects: Peptides -- Synthesis , Macrocyclic compounds , Drug development , Drug discovery , Cardiovascular system -- Diseases -- Prevention , Proteins -- Synthesis
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/116056 , vital:34293
- Description: Peptides are uniquely endowed with features that allow them to perturb previously difficult to drug biomolecular targets. Peptide macrocycles in particular have seen a flurry of recent interest due to their enhanced bioavailability, tunability and specificity. Although these properties make them attractive hit-candidates in early stage drug discovery, knowing which peptides to pursue is non‐trivial due to the magnitude of the peptide sequence space. Computational screening approaches show promise in their ability to address the size of this search space but suffer from their inability to accurately interrogate the conformational landscape of peptide macrocycles. We developed an in‐silico compound enumerator that was tasked with populating a conformationally laden peptide virtual library. This library was then used in the search for cardio‐protective agents (that may be administered, reducing tissue damage during reperfusion after ischemia (heart attacks)). Our enumerator successfully generated a library of 15.2 billion compounds, requiring the use of compression algorithms, conformational sampling protocols and management of aggregated compute resources in the context of a local cluster. In the absence of experimental biophysical data, we performed biased sampling during alchemical molecular dynamics simulations in order to observe cyclophilin‐D perturbation by cyclosporine A and its mitochondrial targeted analogue. Reliable intermediate state averaging through a WHAM analysis of the biased dynamic pulling simulations confirmed that the cardio‐protective activity of cyclosporine A was due to its mitochondrial targeting. Paralleltempered solution molecular dynamics in combination with efficient clustering isolated the essential dynamics of a cyclic peptide scaffold. The rapid enumeration of skeletons from these essential dynamics gave rise to a conformation laden virtual library of all the 15.2 Billion unique cyclic peptides (given the limits on peptide sequence imposed). Analysis of this library showed the exact extent of physicochemical properties covered, relative to the bare scaffold precursor. Molecular docking of a subset of the virtual library against cyclophilin‐D showed significant improvements in affinity to the target (relative to cyclosporine A). The conformation laden virtual library, accessed by our methodology, provided derivatives that were able to make many interactions per peptide with the cyclophilin‐D target. Machine learning methods showed promise in the training of Support Vector Machines for synthetic feasibility prediction for this library. The synergy between enumeration and conformational sampling greatly improves the performance of this library during virtual screening, even when only a subset is used.
- Full Text:
- Date Issued: 2019
- Authors: Sigauke, Lester Takunda
- Date: 2019
- Subjects: Peptides -- Synthesis , Macrocyclic compounds , Drug development , Drug discovery , Cardiovascular system -- Diseases -- Prevention , Proteins -- Synthesis
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/116056 , vital:34293
- Description: Peptides are uniquely endowed with features that allow them to perturb previously difficult to drug biomolecular targets. Peptide macrocycles in particular have seen a flurry of recent interest due to their enhanced bioavailability, tunability and specificity. Although these properties make them attractive hit-candidates in early stage drug discovery, knowing which peptides to pursue is non‐trivial due to the magnitude of the peptide sequence space. Computational screening approaches show promise in their ability to address the size of this search space but suffer from their inability to accurately interrogate the conformational landscape of peptide macrocycles. We developed an in‐silico compound enumerator that was tasked with populating a conformationally laden peptide virtual library. This library was then used in the search for cardio‐protective agents (that may be administered, reducing tissue damage during reperfusion after ischemia (heart attacks)). Our enumerator successfully generated a library of 15.2 billion compounds, requiring the use of compression algorithms, conformational sampling protocols and management of aggregated compute resources in the context of a local cluster. In the absence of experimental biophysical data, we performed biased sampling during alchemical molecular dynamics simulations in order to observe cyclophilin‐D perturbation by cyclosporine A and its mitochondrial targeted analogue. Reliable intermediate state averaging through a WHAM analysis of the biased dynamic pulling simulations confirmed that the cardio‐protective activity of cyclosporine A was due to its mitochondrial targeting. Paralleltempered solution molecular dynamics in combination with efficient clustering isolated the essential dynamics of a cyclic peptide scaffold. The rapid enumeration of skeletons from these essential dynamics gave rise to a conformation laden virtual library of all the 15.2 Billion unique cyclic peptides (given the limits on peptide sequence imposed). Analysis of this library showed the exact extent of physicochemical properties covered, relative to the bare scaffold precursor. Molecular docking of a subset of the virtual library against cyclophilin‐D showed significant improvements in affinity to the target (relative to cyclosporine A). The conformation laden virtual library, accessed by our methodology, provided derivatives that were able to make many interactions per peptide with the cyclophilin‐D target. Machine learning methods showed promise in the training of Support Vector Machines for synthetic feasibility prediction for this library. The synergy between enumeration and conformational sampling greatly improves the performance of this library during virtual screening, even when only a subset is used.
- Full Text:
- Date Issued: 2019
Evaluation of pre-treatment methods on production of bioethanol from bagasse and sugarcane trash
- Authors: Dodo, Charlie Marembo
- Date: 2019
- Subjects: Lignocellulose
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15387 , vital:40403
- Description: A variety of methods have been researched on for bioethanol preparation from different feedstocks. Amongst the available feedstock, one such feedstock is the sugarcane plant. In most of the research on bioethanol preparation with sugarcane the sugary juice has been widely used, with the bagasse and trash having been discarded as waste. The “waste” bagasse and trash are usually removed and thrown away or burnt during harvesting or in sugar mills to supplement energy requirements. This research on lignocellulosic bagasse and trash was done so as not to discard them but to rather find ways in which to use this biomass constructively. Alternatives to burning that can potentially add value to this biomass need to be researched on by evaluating their hydrolysis content. The different lignocellulose pretreatment methods of concentrated and dilute acid pretreatment, with subsequent enzyme hydrolysis as well as alkali and oxidative alkali pretreatment with enzyme hydrolysis were experimented on the bagasse and trash for hydrolysis efficiency and effectiveness. There are two types of acid hydrolysis which were investigated on which are concentrated and dilute sulphuric acid pretreatments. Use of concentrated sulphuric acid yielded the highest amounts of reducing sugars but also resulted in the highest amounts of downstream process inhibitors formation. This resulted in the need for neutralisation steps which in turn increase the overall costs of using this method to obtain reducing sugars. It has however the advantage of occurring at a faster rate, within minutes or hours, than using biological enzymes which took days, up to 72 hours to obtain the highest reducing sugar amounts. Dilute sulphuric acid pretreatment offered the advantage of using fewer chemicals which are therefore less severe on equipment and result in fewer fermentation inhibitors being formed. Dilute sulphuric acid hydrolysis also takes a relatively shorter period than biological methods of pretreatment. A challenge of fermentation inhibitors formed during acid hydrolysis was countered by using the methods of overliming (calcium hydroxide) and comparing it to neutralization with sodium hydroxide. Alkali pretreatment with sodium hydroxide was researched on by applying different pretreatment concentrations during experiments on the lignocellulosic biomass. There was an increase in the available quantities of cellulose with a significant reduction in lignin with pretreatment. Alkali pretreatment proved effective in exposing the cellulose which made v more cellulose surface area available to cellulase enzymes for enzyme hydrolysis. The highest yield of reducing sugars was obtained from hydrolysates pretreated with 0.25 M sodium hydroxide for 60 min and a period of 72 h of enzyme hydrolysis. In general the longer the pretreatment time the more reducing sugars were produced from the enzyme hydrolysis. Alkali peroxide pretreatment also resulted in significant reductions in lignin quantities of lignocellulose material. In this method sodium hydroxide in combination with hydrogen peroxide were used in pretreating the biomass. Hydrolysates with even fewer fermentation inhibitors were produced as a result. The highest percentage concentration of cellulose of 63% (g/g) was achieved after pretreatment of bagasse with 5% alkali hydrogen peroxide and trash with 0,25M sodium hydroxide pretreatment. Pretreatment of biomass using alkali with subsequent enzymatic hydrolysis gave the highest yields of fermentable sugars of 38% (g/g) using 7% (v/v) alkali peroxide pre-treated trash than 36% (g/g) for 5% (v/v) with the least inhibitors. Reducing sugar yields of 25% (g/g) and 22% (g/g) were obtained after pretreatment with concentrated and dilute acid respectively. Neutralization of the acid hydrolysates was necessary to reduce inhibitors formed with neutralisation by sodium hydroxide resulting in low dilutions and loss of fermentable sugars as unlike in the case of overliming. Subsequent steps of fermenting the reducing sugars resulting from pretreatment into bioethanol were based on using the yeast Saccharomyces cerevisae. Pretreatment hydrolysates from alkali peroxide experiments produced higher bioethanol yields of 13.7 (g/l) after enzyme hydrolysates versus 6.9 (g/l) bioethanol from dilute acid hydrolyzates. A comparison of the effects of time showed there was more bioethanol yield of 13.7 (g/l) after 72 h of fermentation with the yeast versus 7.0 (g/l) bioethanol after pretreatment for 24 h. The only drawback is the longer fermentation period which thus reduces the process and so reduces the value of the increase in yield
- Full Text:
- Date Issued: 2019
- Authors: Dodo, Charlie Marembo
- Date: 2019
- Subjects: Lignocellulose
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15387 , vital:40403
- Description: A variety of methods have been researched on for bioethanol preparation from different feedstocks. Amongst the available feedstock, one such feedstock is the sugarcane plant. In most of the research on bioethanol preparation with sugarcane the sugary juice has been widely used, with the bagasse and trash having been discarded as waste. The “waste” bagasse and trash are usually removed and thrown away or burnt during harvesting or in sugar mills to supplement energy requirements. This research on lignocellulosic bagasse and trash was done so as not to discard them but to rather find ways in which to use this biomass constructively. Alternatives to burning that can potentially add value to this biomass need to be researched on by evaluating their hydrolysis content. The different lignocellulose pretreatment methods of concentrated and dilute acid pretreatment, with subsequent enzyme hydrolysis as well as alkali and oxidative alkali pretreatment with enzyme hydrolysis were experimented on the bagasse and trash for hydrolysis efficiency and effectiveness. There are two types of acid hydrolysis which were investigated on which are concentrated and dilute sulphuric acid pretreatments. Use of concentrated sulphuric acid yielded the highest amounts of reducing sugars but also resulted in the highest amounts of downstream process inhibitors formation. This resulted in the need for neutralisation steps which in turn increase the overall costs of using this method to obtain reducing sugars. It has however the advantage of occurring at a faster rate, within minutes or hours, than using biological enzymes which took days, up to 72 hours to obtain the highest reducing sugar amounts. Dilute sulphuric acid pretreatment offered the advantage of using fewer chemicals which are therefore less severe on equipment and result in fewer fermentation inhibitors being formed. Dilute sulphuric acid hydrolysis also takes a relatively shorter period than biological methods of pretreatment. A challenge of fermentation inhibitors formed during acid hydrolysis was countered by using the methods of overliming (calcium hydroxide) and comparing it to neutralization with sodium hydroxide. Alkali pretreatment with sodium hydroxide was researched on by applying different pretreatment concentrations during experiments on the lignocellulosic biomass. There was an increase in the available quantities of cellulose with a significant reduction in lignin with pretreatment. Alkali pretreatment proved effective in exposing the cellulose which made v more cellulose surface area available to cellulase enzymes for enzyme hydrolysis. The highest yield of reducing sugars was obtained from hydrolysates pretreated with 0.25 M sodium hydroxide for 60 min and a period of 72 h of enzyme hydrolysis. In general the longer the pretreatment time the more reducing sugars were produced from the enzyme hydrolysis. Alkali peroxide pretreatment also resulted in significant reductions in lignin quantities of lignocellulose material. In this method sodium hydroxide in combination with hydrogen peroxide were used in pretreating the biomass. Hydrolysates with even fewer fermentation inhibitors were produced as a result. The highest percentage concentration of cellulose of 63% (g/g) was achieved after pretreatment of bagasse with 5% alkali hydrogen peroxide and trash with 0,25M sodium hydroxide pretreatment. Pretreatment of biomass using alkali with subsequent enzymatic hydrolysis gave the highest yields of fermentable sugars of 38% (g/g) using 7% (v/v) alkali peroxide pre-treated trash than 36% (g/g) for 5% (v/v) with the least inhibitors. Reducing sugar yields of 25% (g/g) and 22% (g/g) were obtained after pretreatment with concentrated and dilute acid respectively. Neutralization of the acid hydrolysates was necessary to reduce inhibitors formed with neutralisation by sodium hydroxide resulting in low dilutions and loss of fermentable sugars as unlike in the case of overliming. Subsequent steps of fermenting the reducing sugars resulting from pretreatment into bioethanol were based on using the yeast Saccharomyces cerevisae. Pretreatment hydrolysates from alkali peroxide experiments produced higher bioethanol yields of 13.7 (g/l) after enzyme hydrolysates versus 6.9 (g/l) bioethanol from dilute acid hydrolyzates. A comparison of the effects of time showed there was more bioethanol yield of 13.7 (g/l) after 72 h of fermentation with the yeast versus 7.0 (g/l) bioethanol after pretreatment for 24 h. The only drawback is the longer fermentation period which thus reduces the process and so reduces the value of the increase in yield
- Full Text:
- Date Issued: 2019
Examination of teacher mediation and its impact on foundational reading skills in Grade-R classrooms in Namibia
- Authors: Nzwala, Kenneth
- Date: 2019
- Subjects: Reading (Elementary) -- Namibia -- Case studies , Elementary school teachers -- Namibia -- Case studies , Early childhood education -- Curricula -- Namibia , Vygotskiĭ, L. S. (Lev Semenovich), 1896-1934
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/92291 , vital:30700
- Description: Grounded in the Sociocultural Theory (SCT) of Lev Vygotsky, this study examined teacher mediation and its impact on development of foundational reading skills in six Grade-R classrooms in the Zambezi Region of Namibia. It was a multiple case study with a mixed methods approach. Six Grade R classes attached to primary schools were studied to facilitate following of the same learners to Grade One. A purposive sampling technique was used to draw a sample of six Grade-R and Grade-One teachers. Learners were selected using stratified random sampling. Data were collected by means of interviews, observation of Grade R lessons, and an emergent Early Grade Reading Assessment (eEGRA) test. eEGRA facilitated benchmarking teacher efficacy in mediating Grade R learners’ foundational reading skills. Nine Grade One learners per teacher per school took part in the test at the beginning of Grade One. Three 35-minute lessons, per Grade-R teacher, were observed. Data were analysed statistically using ANOVA with thematic qualitative analysis of interview data against document analysis of curricula, teacher planning and learner exercise books. The study established that teachers had no understanding of ‘emergent literacy’, did not promote a love of books, or promote learning through play. There was evidence of a language barrier during lessons, which potentially reduced the efficacy of teacher mediation. The curriculum was found to be inappropriate as it lacked guidance relevant to Grade R teachers. This point was particularly pertinent as all teachers in this study had not received Grade-R training and were therefore looking to the curriculum for support. The difference between what teachers said and what they did was revealed in their classroom practice. Lesson planning was found to be superficial and non-reflective, with a marked discrepancy between what was planned and what was done. The style of pedagogy was primarily transmissive and authoritarian. Finally, the socio-economic distribution of the schools did not demonstrate significant impact on learner performance in the benchmark test. This study concludes that the Grade-R curriculum needs to be revised to be culturally and age appropriate. Teachers should be trained to understand the speciality of Grade R, and support should be given to current teachers to adopt a child-centred, play-based approach to pedagogy.
- Full Text:
- Date Issued: 2019
- Authors: Nzwala, Kenneth
- Date: 2019
- Subjects: Reading (Elementary) -- Namibia -- Case studies , Elementary school teachers -- Namibia -- Case studies , Early childhood education -- Curricula -- Namibia , Vygotskiĭ, L. S. (Lev Semenovich), 1896-1934
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/92291 , vital:30700
- Description: Grounded in the Sociocultural Theory (SCT) of Lev Vygotsky, this study examined teacher mediation and its impact on development of foundational reading skills in six Grade-R classrooms in the Zambezi Region of Namibia. It was a multiple case study with a mixed methods approach. Six Grade R classes attached to primary schools were studied to facilitate following of the same learners to Grade One. A purposive sampling technique was used to draw a sample of six Grade-R and Grade-One teachers. Learners were selected using stratified random sampling. Data were collected by means of interviews, observation of Grade R lessons, and an emergent Early Grade Reading Assessment (eEGRA) test. eEGRA facilitated benchmarking teacher efficacy in mediating Grade R learners’ foundational reading skills. Nine Grade One learners per teacher per school took part in the test at the beginning of Grade One. Three 35-minute lessons, per Grade-R teacher, were observed. Data were analysed statistically using ANOVA with thematic qualitative analysis of interview data against document analysis of curricula, teacher planning and learner exercise books. The study established that teachers had no understanding of ‘emergent literacy’, did not promote a love of books, or promote learning through play. There was evidence of a language barrier during lessons, which potentially reduced the efficacy of teacher mediation. The curriculum was found to be inappropriate as it lacked guidance relevant to Grade R teachers. This point was particularly pertinent as all teachers in this study had not received Grade-R training and were therefore looking to the curriculum for support. The difference between what teachers said and what they did was revealed in their classroom practice. Lesson planning was found to be superficial and non-reflective, with a marked discrepancy between what was planned and what was done. The style of pedagogy was primarily transmissive and authoritarian. Finally, the socio-economic distribution of the schools did not demonstrate significant impact on learner performance in the benchmark test. This study concludes that the Grade-R curriculum needs to be revised to be culturally and age appropriate. Teachers should be trained to understand the speciality of Grade R, and support should be given to current teachers to adopt a child-centred, play-based approach to pedagogy.
- Full Text:
- Date Issued: 2019
Examining mathematical reasoning through enacted visualisation
- Authors: Dongwi, Beata Lididimikeni
- Date: 2019
- Subjects: Visualization , Mathematics -- Study and teaching -- Namibia , Mathematics -- Study and teaching -- Audio-visual aids , Geometry -- Study and teaching , Reasoning , Mathematical ability
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/68192 , vital:29217
- Description: This study sets out to analyse the co-emergence of visualisation and reasoning processes when selected learners engaged in solving word problems. The study argues that visualisation processes and mathematical reasoning processes are closely interlinked in the process of engaging in any mathematical activity. This qualitative research project adopted a case study methodology embedded within a broader interpretative orientation. The research participants were a cohort of 17 mixedgender and mixed-ability Grade 11 learners from a private school in southern Namibia. Data was collected in three phases and comprised of one-on-one task-based interviews in the first phase, focus group task-based interviews in the second, and semi-structured reflective interviews in the third. The analytical framework was informed by elements of enactivism and consisted of a hybrid of observable visualisation and mathematical reasoning indicators. The study was framed by an enactivist perspective that served as a linking mediator to bring visualisation and reasoning processes together, and as a lens through which the coemergence of these processes was observed and analysed. The key enactivist concepts of structural coupling and co-emergence were the two mediating ideas that enabled me to discuss the links between visualisation and reasoning that emerged whilst my participants solved the set word problems. The study argues that the visualisation processes enacted by the participants when solving these problems are inseparable from the reasoning processes that the participants brought to bear; that is, they co-emerged.
- Full Text:
- Date Issued: 2019
- Authors: Dongwi, Beata Lididimikeni
- Date: 2019
- Subjects: Visualization , Mathematics -- Study and teaching -- Namibia , Mathematics -- Study and teaching -- Audio-visual aids , Geometry -- Study and teaching , Reasoning , Mathematical ability
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/68192 , vital:29217
- Description: This study sets out to analyse the co-emergence of visualisation and reasoning processes when selected learners engaged in solving word problems. The study argues that visualisation processes and mathematical reasoning processes are closely interlinked in the process of engaging in any mathematical activity. This qualitative research project adopted a case study methodology embedded within a broader interpretative orientation. The research participants were a cohort of 17 mixedgender and mixed-ability Grade 11 learners from a private school in southern Namibia. Data was collected in three phases and comprised of one-on-one task-based interviews in the first phase, focus group task-based interviews in the second, and semi-structured reflective interviews in the third. The analytical framework was informed by elements of enactivism and consisted of a hybrid of observable visualisation and mathematical reasoning indicators. The study was framed by an enactivist perspective that served as a linking mediator to bring visualisation and reasoning processes together, and as a lens through which the coemergence of these processes was observed and analysed. The key enactivist concepts of structural coupling and co-emergence were the two mediating ideas that enabled me to discuss the links between visualisation and reasoning that emerged whilst my participants solved the set word problems. The study argues that the visualisation processes enacted by the participants when solving these problems are inseparable from the reasoning processes that the participants brought to bear; that is, they co-emerged.
- Full Text:
- Date Issued: 2019
Expanding learning in clergy leadership formation in an Anglican Church Province in Southern Africa: a critical realist study
- Authors: Chinganga, Percy
- Date: 2019
- Subjects: Leadership -- Africa, Southern -- Religious aspects -- Christianity , Church management -- Africa, Southern , Critical realism , Educational leadership , Anglican Church of Southern Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/92258 , vital:30704
- Description: The focus of this study was to investigate the kind of learning that happened when participants involved in clergy leadership formation programmes and activities in the Anglican Church of Southern Africa (ACSA) engaged in their responsibilities as a collective. Further, the research sought to explore collaborative and transforming practices in ACSA clergy leadership formation programmes and activities which could be expanded through learning. The study is premised on an investigation of the historical foundations of Christian leadership formation processes which sought to establish clergy leadership formation models relevant to ACSA (the context of the study) from inception (1848) to date (2017). This entailed investigating how the developments which have happened in the church from its inception in the New Testament times through the Medieval and Reformation periods, have contributed to the emergence of distinct Christian leadership formation models which have formed the basis of clergy leadership formation in ACSA. Accordingly, the study highlighted key issues relating to clergy leadership formation which are discernible in the different historical phases of the life and work of the church with the objective of establishing how ACSA, through expansive learning, could transform her current clergy leadership formation model(s) towards collaborative and transforming practices. The concept of expansive learning, drawn from Cultural Historical Activity Theory (CHAT), was used in the study as a methodological tool to create an environment where research participants (formators) from several dioceses would engage in collective work activities which would surface contradictions relating to how clergy leadership formation programmes and activities were understood and facilitated in ACSA. In response to the surfaced contradictions, the study engaged research participants in Change Laboratory Workshops whose goal was to transform the organisation (ACSA) in two particular ways: empowerment of participants (formators) with conceptual tools relevant to their responsibilities in clergy leadership formation programmes and activities in ACSA, and improvement of organisational cultural practices, that is, the manner in which ACSA ought to conceptualise, design, plan, facilitate and manage clergy leadership formation programmes and activities. The latter brought into the discourse the need for participants (formators) to select and employ methodologies, methods, approaches and resources relevant to the southern African context where ACSA is located even though the study also acknowledged the influence of other Anglican Church contexts on what happened at the local level. In order to decipher meaning out of investigated phenomena about clergy leadership formation in ACSA, the study employed the critical realist “underlabouring” philosophy advanced by theorists such as Bhaskar to surface underlying mechanisms that exist at the level of the “real” in order to understand the causes of particular events and experiences as they manifest in the “actual” and “empirical” domains of the world, ACSA in the case of the study. In particular, the study engaged critically the opinion deliberated by critical realists concerning the interplay between structure and agency in relation to the responsibilities of the research participants (formators) in ACSA clergy leadership formation programmes and activities. For instance, the study had an interest in investigating why bishops (principal formators in ACSA) exercised their episcopal authority in the manner they do and why individual formators were concerned about particular issues which relate to the facilitation of clergy leadership formation in ACSA (agential reflexivity/subjectivity). The study observed that, in the case of diocesan bishops, critical realists would argue that, by virtue of the authority which comes with their responsibilities (agency), they have the power to influence transformation of practices in clergy leadership formation in ACSA at any given point in time. The flip side of the discourse was also taken note of: that some bishops, for reasons known to themselves and their predecessors, are often reluctant to embrace new ideas relating to clergy leadership formation practices in their dioceses. Further, through critical realist lens, the study concluded that Canons, Vision and Mission statements, Acts, and structures such as Synod of Bishops, Provincial Synod, ABoTE, Cott, and TfM structurally shape ACSA, thus providing the organisation with a stable ontology which ought to direct, regulate and control the manner in which clergy leadership formation programmes and activities were conceptualised, designed, planned, facilitated and managed. As such, the study had an interest in establishing what would happen, in relation to clergy leadership formation practices in ACSA, when these structures would have been activated? Beyond that, in view of the goal of the study, it was enquired how expansive learning processes could be helpful in responding to the research findings towards exploring collaborative and transforming clergy leadership formation practices in ACSA. Drawing from the conceptual framework which was carved in the study on the basis of the theoretical tools (critical realism and educational leadership theory) and methodological tools (CHAT orientated concepts) undergirded by the Vygotskian theorisation of human consciousness development, the study concluded that clergy leadership formation is a collaborative activity which calls for the recognition, appreciation and utilisation of available expertise in ACSA and provision of a platform where participants (formators) could engage collectively on issues relating to their work with the objective of building each other up in knowledge and skills (expansive learning) towards realisation of the goals and objectives of the organisation. Diverse understandings (contradictions) of what needed to be prioritised in the facilitation of clergy leadership formation in ACSA would be considered as a positive rather than a negative. Ultimately, through the use of inductive, abductive and retroductive modes of inference, the study modelled a transforming, transformational, transformative, embodied and incarnational model of clergy leadership formation which ACSA could consider using in future deliberations on the object of study particularly in relation to the key research findings across the case studies which were used in the study.
- Full Text:
- Date Issued: 2019
- Authors: Chinganga, Percy
- Date: 2019
- Subjects: Leadership -- Africa, Southern -- Religious aspects -- Christianity , Church management -- Africa, Southern , Critical realism , Educational leadership , Anglican Church of Southern Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/92258 , vital:30704
- Description: The focus of this study was to investigate the kind of learning that happened when participants involved in clergy leadership formation programmes and activities in the Anglican Church of Southern Africa (ACSA) engaged in their responsibilities as a collective. Further, the research sought to explore collaborative and transforming practices in ACSA clergy leadership formation programmes and activities which could be expanded through learning. The study is premised on an investigation of the historical foundations of Christian leadership formation processes which sought to establish clergy leadership formation models relevant to ACSA (the context of the study) from inception (1848) to date (2017). This entailed investigating how the developments which have happened in the church from its inception in the New Testament times through the Medieval and Reformation periods, have contributed to the emergence of distinct Christian leadership formation models which have formed the basis of clergy leadership formation in ACSA. Accordingly, the study highlighted key issues relating to clergy leadership formation which are discernible in the different historical phases of the life and work of the church with the objective of establishing how ACSA, through expansive learning, could transform her current clergy leadership formation model(s) towards collaborative and transforming practices. The concept of expansive learning, drawn from Cultural Historical Activity Theory (CHAT), was used in the study as a methodological tool to create an environment where research participants (formators) from several dioceses would engage in collective work activities which would surface contradictions relating to how clergy leadership formation programmes and activities were understood and facilitated in ACSA. In response to the surfaced contradictions, the study engaged research participants in Change Laboratory Workshops whose goal was to transform the organisation (ACSA) in two particular ways: empowerment of participants (formators) with conceptual tools relevant to their responsibilities in clergy leadership formation programmes and activities in ACSA, and improvement of organisational cultural practices, that is, the manner in which ACSA ought to conceptualise, design, plan, facilitate and manage clergy leadership formation programmes and activities. The latter brought into the discourse the need for participants (formators) to select and employ methodologies, methods, approaches and resources relevant to the southern African context where ACSA is located even though the study also acknowledged the influence of other Anglican Church contexts on what happened at the local level. In order to decipher meaning out of investigated phenomena about clergy leadership formation in ACSA, the study employed the critical realist “underlabouring” philosophy advanced by theorists such as Bhaskar to surface underlying mechanisms that exist at the level of the “real” in order to understand the causes of particular events and experiences as they manifest in the “actual” and “empirical” domains of the world, ACSA in the case of the study. In particular, the study engaged critically the opinion deliberated by critical realists concerning the interplay between structure and agency in relation to the responsibilities of the research participants (formators) in ACSA clergy leadership formation programmes and activities. For instance, the study had an interest in investigating why bishops (principal formators in ACSA) exercised their episcopal authority in the manner they do and why individual formators were concerned about particular issues which relate to the facilitation of clergy leadership formation in ACSA (agential reflexivity/subjectivity). The study observed that, in the case of diocesan bishops, critical realists would argue that, by virtue of the authority which comes with their responsibilities (agency), they have the power to influence transformation of practices in clergy leadership formation in ACSA at any given point in time. The flip side of the discourse was also taken note of: that some bishops, for reasons known to themselves and their predecessors, are often reluctant to embrace new ideas relating to clergy leadership formation practices in their dioceses. Further, through critical realist lens, the study concluded that Canons, Vision and Mission statements, Acts, and structures such as Synod of Bishops, Provincial Synod, ABoTE, Cott, and TfM structurally shape ACSA, thus providing the organisation with a stable ontology which ought to direct, regulate and control the manner in which clergy leadership formation programmes and activities were conceptualised, designed, planned, facilitated and managed. As such, the study had an interest in establishing what would happen, in relation to clergy leadership formation practices in ACSA, when these structures would have been activated? Beyond that, in view of the goal of the study, it was enquired how expansive learning processes could be helpful in responding to the research findings towards exploring collaborative and transforming clergy leadership formation practices in ACSA. Drawing from the conceptual framework which was carved in the study on the basis of the theoretical tools (critical realism and educational leadership theory) and methodological tools (CHAT orientated concepts) undergirded by the Vygotskian theorisation of human consciousness development, the study concluded that clergy leadership formation is a collaborative activity which calls for the recognition, appreciation and utilisation of available expertise in ACSA and provision of a platform where participants (formators) could engage collectively on issues relating to their work with the objective of building each other up in knowledge and skills (expansive learning) towards realisation of the goals and objectives of the organisation. Diverse understandings (contradictions) of what needed to be prioritised in the facilitation of clergy leadership formation in ACSA would be considered as a positive rather than a negative. Ultimately, through the use of inductive, abductive and retroductive modes of inference, the study modelled a transforming, transformational, transformative, embodied and incarnational model of clergy leadership formation which ACSA could consider using in future deliberations on the object of study particularly in relation to the key research findings across the case studies which were used in the study.
- Full Text:
- Date Issued: 2019
Exploring emotional intelligence perceptions of school leaders in relation to social justice: a case study
- Authors: Bese, Samuel
- Date: 2019
- Subjects: Educational leadership
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/36529 , vital:33963
- Description: The aim of this study was to explore school leaders’ perceptions of intrapersonal and interpersonal emotional intelligence (EI) in relation to social justice aspects, such as equity, access and inclusive participation in the Libode Educational District of Eastern Cape Province. This district, like many other rural districts in South Africa, has to face critical leadership issues, which have an influence on how school leaders could enact social justice practices in schools (DoE, 2012). This qualitative study employed twelve in-depth interview research participants, which included 6 purposively selected principals and 6 deputy principals. Data collection and content analysis also included the following: 6 focus group interviews with head of departments (HODs) and school governing bodies (SGBs); document analysis of the minutes of school meetings; and Department of Education (DoE) memorandums. The key findings that emerged through the descriptive, exploratory, social interpretive perspectives used in this study revealed the relevance of: • school leaders’ perceptions of intrapersonal EI in enhancing social justice practices with regard to equity, access, and inclusive participation; and • school leaders’ perceptions of interpersonal EI in enhancing social justice practices with regard to equity, access, and inclusive participation. The research participants’ perceptions of EI promoted deeper understanding of how school leaders could engage in social justice in relation to school leadership, teamwork, building bonds, developing others, becoming change agents, and managing conflicts in their schools. The study also captured that EI leaders can greatly manage their emotions to enhance their abilities to identify and control their destructive impulses as well as understanding and handling others’ emotions. It would be commendable for school leaders to have a deeper understanding of how their emotions could enhance social justice in their schools.
- Full Text:
- Date Issued: 2019
- Authors: Bese, Samuel
- Date: 2019
- Subjects: Educational leadership
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/36529 , vital:33963
- Description: The aim of this study was to explore school leaders’ perceptions of intrapersonal and interpersonal emotional intelligence (EI) in relation to social justice aspects, such as equity, access and inclusive participation in the Libode Educational District of Eastern Cape Province. This district, like many other rural districts in South Africa, has to face critical leadership issues, which have an influence on how school leaders could enact social justice practices in schools (DoE, 2012). This qualitative study employed twelve in-depth interview research participants, which included 6 purposively selected principals and 6 deputy principals. Data collection and content analysis also included the following: 6 focus group interviews with head of departments (HODs) and school governing bodies (SGBs); document analysis of the minutes of school meetings; and Department of Education (DoE) memorandums. The key findings that emerged through the descriptive, exploratory, social interpretive perspectives used in this study revealed the relevance of: • school leaders’ perceptions of intrapersonal EI in enhancing social justice practices with regard to equity, access, and inclusive participation; and • school leaders’ perceptions of interpersonal EI in enhancing social justice practices with regard to equity, access, and inclusive participation. The research participants’ perceptions of EI promoted deeper understanding of how school leaders could engage in social justice in relation to school leadership, teamwork, building bonds, developing others, becoming change agents, and managing conflicts in their schools. The study also captured that EI leaders can greatly manage their emotions to enhance their abilities to identify and control their destructive impulses as well as understanding and handling others’ emotions. It would be commendable for school leaders to have a deeper understanding of how their emotions could enhance social justice in their schools.
- Full Text:
- Date Issued: 2019
Exploring the interplay of sociolinguistic factors in the teaching of esl at secondary school level in Zimbabwe
- Authors: Jhamba , Duren
- Date: 2019
- Subjects: Sociolinguistics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15770 , vital:40522
- Description: The researcher noted that earlier second language teaching models tended to treat language as an artefact to be scrutinised and adhered to with grammatical precision. This tended to reduce all language learning to the mere acquisition of grammatical skills. However, since all language behaviour is embedded in sociocultural and contextual frameworks, all teaching should provide cross-cultural awareness of that complexity as well as of the internal variation within language. Therefore, the research explored the interplay of sociolinguistic factors in the teaching of English in Zimbabwe. The Mixed Methods design; a combination of the descriptive survey and the case study was adopted. The questionnaire, interview, observation and document analysis methods were used to collect both qualitative and quantitative data to assess the role of sociolinguistic factors in second language teaching pedagogy. A combination of convenient sampling and stratified random sampling was used to come up with a sample representative of the school categories and the gender of teachers in the 38 secondary schools in Gweru District. The data for the research was collected from a random sample of 50 teachers. The data analysis supported the need for a reconceptualisation of ESL teaching in Zimbabwe. Notably, language teaching tended to be exam-centric, unimaginative and not well linked to the needs of the learners in the communicative environment outside the school. This confirmed the initial observation that the secondary school graduates generally lacked sociolinguistic competence skills. The teachers were, however generally not motivated to include culture and sociolinguistics in their teaching. The research therefore recommended a revisit of the 7 | Page allowance for the interplay of sociolinguistic factors at all the planning stages of the ESL curriculum; the status, corpus and acquisition stages.
- Full Text:
- Date Issued: 2019
- Authors: Jhamba , Duren
- Date: 2019
- Subjects: Sociolinguistics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15770 , vital:40522
- Description: The researcher noted that earlier second language teaching models tended to treat language as an artefact to be scrutinised and adhered to with grammatical precision. This tended to reduce all language learning to the mere acquisition of grammatical skills. However, since all language behaviour is embedded in sociocultural and contextual frameworks, all teaching should provide cross-cultural awareness of that complexity as well as of the internal variation within language. Therefore, the research explored the interplay of sociolinguistic factors in the teaching of English in Zimbabwe. The Mixed Methods design; a combination of the descriptive survey and the case study was adopted. The questionnaire, interview, observation and document analysis methods were used to collect both qualitative and quantitative data to assess the role of sociolinguistic factors in second language teaching pedagogy. A combination of convenient sampling and stratified random sampling was used to come up with a sample representative of the school categories and the gender of teachers in the 38 secondary schools in Gweru District. The data for the research was collected from a random sample of 50 teachers. The data analysis supported the need for a reconceptualisation of ESL teaching in Zimbabwe. Notably, language teaching tended to be exam-centric, unimaginative and not well linked to the needs of the learners in the communicative environment outside the school. This confirmed the initial observation that the secondary school graduates generally lacked sociolinguistic competence skills. The teachers were, however generally not motivated to include culture and sociolinguistics in their teaching. The research therefore recommended a revisit of the 7 | Page allowance for the interplay of sociolinguistic factors at all the planning stages of the ESL curriculum; the status, corpus and acquisition stages.
- Full Text:
- Date Issued: 2019
From ‘cleanliness is next to Godliness’ to ‘without perfect health, there is nothing’: discourses of healthy lifestyle in the construction of young adult identities in urban South Africa
- Authors: De Jong, Michelle
- Date: 2019
- Subjects: Health , Cleanliness , Social structure -- Health aspects , Health behavior , Social medicine
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64940 , vital:28638
- Description: This research explores popular constructions of “healthiness” as individual lifestyle choices in the context of contemporary South African consumer culture, and how these constructions relate to formations of subjectivity. This is a qualitative study conducted within a social constructionist, theoretical framework. Data was collected using in-depth, semi structured interviews and are analysed using a Foucauldian inspired version of discourse analysis. A critical stance is taken towards the assumption in these discourses that their version of healthiness is always and unquestionably positive. Special attention is paid to the lifestyle and marketing media discourses appropriated in understandings of personal health through self-management, and of the optimization of health in the pursuit of well-being. The ways in which different discourses of healthiness facilitate the construction of specific identities are considered in order to untangle some of the problems created by the moralism underpinning popular consumer health discourse. How constructions of healthiness and aspirant healthy lifestyles support, and are supported by, the ideologies and practices of neoliberal capitalism are also explored. From this perspective, healthiness as lifestyle consumption choices can be seen as an ideological apparatus that produces the subjects necessary to reproduce the social order (Althusser, 2001), functioning not only positively amongst the social classes with the leisure and economic resources to pursue these options, but also negatively as victim-blaming of those who are excluded. The argument here is not that health is bad or that people should not be bothered with activities aimed at promoting good health, but that in a context where the concept of health is idealised as always positive and beneficial, the potentially harmful consequences of some of the health discourses we make use of may be occluded. This idealisation of health or ‘healthism’ may also function to divert attention away from some of the challenges to health that are not the direct result of personal behaviours and are unlikely to be remedied through individually focussed interventions, for example, inequality and inadequate access to basic resources. Six discourses which were used to construct understandings of health are analysed. These include Happiness, Freedom, Control, Care, Balance and Goodness. The ways in which these discourses played a role in constructing the kinds of subject positions which were made available to participants, and the possible implications this has, are explored in depth.
- Full Text:
- Date Issued: 2019
- Authors: De Jong, Michelle
- Date: 2019
- Subjects: Health , Cleanliness , Social structure -- Health aspects , Health behavior , Social medicine
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64940 , vital:28638
- Description: This research explores popular constructions of “healthiness” as individual lifestyle choices in the context of contemporary South African consumer culture, and how these constructions relate to formations of subjectivity. This is a qualitative study conducted within a social constructionist, theoretical framework. Data was collected using in-depth, semi structured interviews and are analysed using a Foucauldian inspired version of discourse analysis. A critical stance is taken towards the assumption in these discourses that their version of healthiness is always and unquestionably positive. Special attention is paid to the lifestyle and marketing media discourses appropriated in understandings of personal health through self-management, and of the optimization of health in the pursuit of well-being. The ways in which different discourses of healthiness facilitate the construction of specific identities are considered in order to untangle some of the problems created by the moralism underpinning popular consumer health discourse. How constructions of healthiness and aspirant healthy lifestyles support, and are supported by, the ideologies and practices of neoliberal capitalism are also explored. From this perspective, healthiness as lifestyle consumption choices can be seen as an ideological apparatus that produces the subjects necessary to reproduce the social order (Althusser, 2001), functioning not only positively amongst the social classes with the leisure and economic resources to pursue these options, but also negatively as victim-blaming of those who are excluded. The argument here is not that health is bad or that people should not be bothered with activities aimed at promoting good health, but that in a context where the concept of health is idealised as always positive and beneficial, the potentially harmful consequences of some of the health discourses we make use of may be occluded. This idealisation of health or ‘healthism’ may also function to divert attention away from some of the challenges to health that are not the direct result of personal behaviours and are unlikely to be remedied through individually focussed interventions, for example, inequality and inadequate access to basic resources. Six discourses which were used to construct understandings of health are analysed. These include Happiness, Freedom, Control, Care, Balance and Goodness. The ways in which these discourses played a role in constructing the kinds of subject positions which were made available to participants, and the possible implications this has, are explored in depth.
- Full Text:
- Date Issued: 2019