Oxygen limitation and thermal tolerance: a comparison of pulmonate and patellogastropod limpets
- Authors: Kankondi, Sebbi
- Date: 2017
- Subjects: Thermal tolerance (Physiology) , Limpets -- Physiology , Limpets -- Effect of temperature on , Oxygen consumption (Physiology)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7570 , vital:21274
- Description: Since the scientific community anticipates a general change in the global climate, it has become increasingly important to develop predictive models which encompass mechanisms to generate reliable forecasts of the effects this change on ecological communities and processes. To this end, the oxygen- and capacity- limited thermal tolerance (OCLTT) theory has been developed as a link between various physiological processes, the thermal aspect of climate change and the associated shifts at different levels of biological organization. This study set out to assess the general applicability of the OCLTT theory in eurythermal pulmonate and patellogastropod limpets, whose distributions overlap on the high shore rocks of the warm temperate, south-east coast of South Africa.This was done by determining their microhabitat use, median lethal temperatures and cardiac, Arrhenius breakpoint temperatures as measures of their upper thermal tolerance limits, in both air and water. The main hypotheses of the study were that the pulmonate limpets would be more common than the patellogastropods in warmer microhabitats during low tide and would have higher thermal limits than the patellogastropods in air and vice versa in water. This was based on the assumption that the two limpet groups have different capabilities of oxygen consumption in air and water, due to differences in their respiratory organs and that this would be reflected in their thermal tolerances based on predictions made by the OCLTT. This assumption was important because oxygen consumption was not measured in this study. Previous research (e.g. Garrity, 1984), showed that a thermal stress gradient exists among rocky intertidal microhabitats. From most to least thermally stressful the gradient is horizontal surfaces> slopes> vertical surfaces> tide pools> crevices. The current study found that, while the pulmonate limpets, Siphonaria capensis and S. serrata, preferred rock pools, sloped, vertical and horizontal rock surfaces, the patellogastropod limpets, Cellana capensis and Scutellastra granularis, preferred rock pools and vertical rock surfaces. Furthermore, the pulmonate limpets were only common on horizontal rock surfaces where specific ameliorating conditions would have mitigated thermal stress there. In addition, C. capensis had similar thermal tolerance limits to the pulmonate limpets in air and the pulmonate limpets had similar and/or higher thermal tolerance limits compared to S. granularis in water. This indicates that the pulmonate limpets did not necessarily prefer warmer microhabitats than the patellogastropod limpets and that there were no differences in the collective upper thermal tolerance limits between the two limpet groups in either medium.Consequently, there was no indication from this study that an assumed superior capacity for oxygen supply translates into greater thermal tolerance and that the hypotheses based on the OCLTT were not supported. Although this was an indirect test of the OCLTT theory, I conclude that this study does not support the notion of its general applicability and that mechanisms other than those outlined by the OCLTT theory may help explain the patterns of thermal limitation observed in the current study.
- Full Text:
- Authors: Kankondi, Sebbi
- Date: 2017
- Subjects: Thermal tolerance (Physiology) , Limpets -- Physiology , Limpets -- Effect of temperature on , Oxygen consumption (Physiology)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7570 , vital:21274
- Description: Since the scientific community anticipates a general change in the global climate, it has become increasingly important to develop predictive models which encompass mechanisms to generate reliable forecasts of the effects this change on ecological communities and processes. To this end, the oxygen- and capacity- limited thermal tolerance (OCLTT) theory has been developed as a link between various physiological processes, the thermal aspect of climate change and the associated shifts at different levels of biological organization. This study set out to assess the general applicability of the OCLTT theory in eurythermal pulmonate and patellogastropod limpets, whose distributions overlap on the high shore rocks of the warm temperate, south-east coast of South Africa.This was done by determining their microhabitat use, median lethal temperatures and cardiac, Arrhenius breakpoint temperatures as measures of their upper thermal tolerance limits, in both air and water. The main hypotheses of the study were that the pulmonate limpets would be more common than the patellogastropods in warmer microhabitats during low tide and would have higher thermal limits than the patellogastropods in air and vice versa in water. This was based on the assumption that the two limpet groups have different capabilities of oxygen consumption in air and water, due to differences in their respiratory organs and that this would be reflected in their thermal tolerances based on predictions made by the OCLTT. This assumption was important because oxygen consumption was not measured in this study. Previous research (e.g. Garrity, 1984), showed that a thermal stress gradient exists among rocky intertidal microhabitats. From most to least thermally stressful the gradient is horizontal surfaces> slopes> vertical surfaces> tide pools> crevices. The current study found that, while the pulmonate limpets, Siphonaria capensis and S. serrata, preferred rock pools, sloped, vertical and horizontal rock surfaces, the patellogastropod limpets, Cellana capensis and Scutellastra granularis, preferred rock pools and vertical rock surfaces. Furthermore, the pulmonate limpets were only common on horizontal rock surfaces where specific ameliorating conditions would have mitigated thermal stress there. In addition, C. capensis had similar thermal tolerance limits to the pulmonate limpets in air and the pulmonate limpets had similar and/or higher thermal tolerance limits compared to S. granularis in water. This indicates that the pulmonate limpets did not necessarily prefer warmer microhabitats than the patellogastropod limpets and that there were no differences in the collective upper thermal tolerance limits between the two limpet groups in either medium.Consequently, there was no indication from this study that an assumed superior capacity for oxygen supply translates into greater thermal tolerance and that the hypotheses based on the OCLTT were not supported. Although this was an indirect test of the OCLTT theory, I conclude that this study does not support the notion of its general applicability and that mechanisms other than those outlined by the OCLTT theory may help explain the patterns of thermal limitation observed in the current study.
- Full Text:
Patterns of plant diversity and cultural meaning in a rural landscape in the Albany Thicket: effects of land-use and topography
- Authors: Ngqiyaza, Nozuko Princess
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50237 , vital:25969
- Description: South Africa is the world's third most bio-diverse country, but pressures on this biodiversity are many and widespread. It is now well recognised that protected areas on their own are insufficient to protect biodiversity, and increasing emphasis is placed on developing models for ensuring the persistence of biodiversity in agricultural and rural landscapes. One of the major challenges, especially in rural areas, is the need to reconcile people’s need to use natural resources with biodiversity conservation. This study aimed to (1) examine the ecosystem services people derive from the natural vegetation and how this is distributed in space and (2) the effects of land use and topo-edaphic factors on species richness, composition and structure and how this is spatially distributed. I investigated two land-use types, i.e. a rural village and adjacent lightly used game farm(s) by comparing 20 sites under each land-use representing the range of topographic position. I sampled respondent’s uses and values, species richness and composition, woody density, structure and composition at these 40 sites. This allowed for comparison between the two land uses but also allowed me to examine the effect of topography and relative soil moisture (both known to have a string influence on vegetation in semi-arid areas), and to relate the ecosystem services to plant species richness, structure and woody composition. People derived a wide range of ecosystem services and this differed with distance from the village and vegetation type. Men and women performed different tasks and had different feelings and derived different use values across the landscapes. Both men and women showed a great appreciation for the thicket forest, Pteronia-dominated and grasslands sites. They recognised these areas and as sacred grounds where they have a strong connection with their ancestors. Women preferred utilising areas closer to the village because they feared crime and wild animals in more remote thicket or forest, while men utilised all areas across the land, but more frequently closer to the village. The older generation had a strong attachment to nature, perceiving it as a provider. The younger generation, especially the young women did not express such a deeply felt connection, but enjoyed getting to see where some of the medicinal plants and useful wood structures were harvested. Younger men would go far into the forest quite regularly, often as far the Great Fish River, when they hunt with their peers. Although a diversity of perceptions were presented, and not all conformed to traditional views and practices, most respondents derived a mix of ecosystem services, with the areas closer to the village providing recreational and direct use value to more people on a more regular basis but spiritual values associated with deep forest persisted, especially among the older generation. Species richness and composition was analysed in relation to Topographic Relative Moisture Index (TRMI), land use and distance from the village to see the effect of topography versus land use on the vegetation. The total number of plant species recorded was 386 for both study sites. Two hundred and ninety two species were recorded in Ntloko and 265 on the game farms. Of the species that were sampled, 121 were recorded in Ntloko only, 94 in the game farms only, and 171 species were shared. The number of useful plant species (fuel, medicine, forage, cultural and edibles) was recorded to be 110, 83 in Ntloko and 63 on the game farms. There was no significant difference in species richness and alpha diversity between the study sites, but the game farms had a higher projected total number of species, reflecting higher beta diversity in the game farms than the communal area. The point-centered quarter method (PCQ) was used to describe woody plant composition, tree density and structure. The woody structure and composition was analysed in relation to the above-mentioned factors and I found no significant difference in the density and overall woody structure and composition between the two study sites. Sites at Ntloko had a positive correlation between soil moisture and woody plant density and a higher density of palatable and unpalatable species. The game farms showed no significant changes in woody plant density with TRMI. This study showed that the communal area maintained comparable plant species richness and vegetation structure and composition to game farms. The rural landscape comprised a gradient from sites close to the village that were heavily impacted, not considered particularly special or sacred but safe, familiar and of utilitarian importance, to sites farther away with denser, less transformed thicket vegetation, which are considered to be of greater cultural, spiritual and aesthetic importance but less safe, familiar and accessible. This suggests that conservation outcomes can be achieved outside protected areas, and that biodiversity is valuable to local residents. Resource management should be implemented to maintain the ecosystem services provided in rural areas in a way that integrates local peoples’ perceptions, goals and values with ecological evidence.
- Full Text:
- Authors: Ngqiyaza, Nozuko Princess
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50237 , vital:25969
- Description: South Africa is the world's third most bio-diverse country, but pressures on this biodiversity are many and widespread. It is now well recognised that protected areas on their own are insufficient to protect biodiversity, and increasing emphasis is placed on developing models for ensuring the persistence of biodiversity in agricultural and rural landscapes. One of the major challenges, especially in rural areas, is the need to reconcile people’s need to use natural resources with biodiversity conservation. This study aimed to (1) examine the ecosystem services people derive from the natural vegetation and how this is distributed in space and (2) the effects of land use and topo-edaphic factors on species richness, composition and structure and how this is spatially distributed. I investigated two land-use types, i.e. a rural village and adjacent lightly used game farm(s) by comparing 20 sites under each land-use representing the range of topographic position. I sampled respondent’s uses and values, species richness and composition, woody density, structure and composition at these 40 sites. This allowed for comparison between the two land uses but also allowed me to examine the effect of topography and relative soil moisture (both known to have a string influence on vegetation in semi-arid areas), and to relate the ecosystem services to plant species richness, structure and woody composition. People derived a wide range of ecosystem services and this differed with distance from the village and vegetation type. Men and women performed different tasks and had different feelings and derived different use values across the landscapes. Both men and women showed a great appreciation for the thicket forest, Pteronia-dominated and grasslands sites. They recognised these areas and as sacred grounds where they have a strong connection with their ancestors. Women preferred utilising areas closer to the village because they feared crime and wild animals in more remote thicket or forest, while men utilised all areas across the land, but more frequently closer to the village. The older generation had a strong attachment to nature, perceiving it as a provider. The younger generation, especially the young women did not express such a deeply felt connection, but enjoyed getting to see where some of the medicinal plants and useful wood structures were harvested. Younger men would go far into the forest quite regularly, often as far the Great Fish River, when they hunt with their peers. Although a diversity of perceptions were presented, and not all conformed to traditional views and practices, most respondents derived a mix of ecosystem services, with the areas closer to the village providing recreational and direct use value to more people on a more regular basis but spiritual values associated with deep forest persisted, especially among the older generation. Species richness and composition was analysed in relation to Topographic Relative Moisture Index (TRMI), land use and distance from the village to see the effect of topography versus land use on the vegetation. The total number of plant species recorded was 386 for both study sites. Two hundred and ninety two species were recorded in Ntloko and 265 on the game farms. Of the species that were sampled, 121 were recorded in Ntloko only, 94 in the game farms only, and 171 species were shared. The number of useful plant species (fuel, medicine, forage, cultural and edibles) was recorded to be 110, 83 in Ntloko and 63 on the game farms. There was no significant difference in species richness and alpha diversity between the study sites, but the game farms had a higher projected total number of species, reflecting higher beta diversity in the game farms than the communal area. The point-centered quarter method (PCQ) was used to describe woody plant composition, tree density and structure. The woody structure and composition was analysed in relation to the above-mentioned factors and I found no significant difference in the density and overall woody structure and composition between the two study sites. Sites at Ntloko had a positive correlation between soil moisture and woody plant density and a higher density of palatable and unpalatable species. The game farms showed no significant changes in woody plant density with TRMI. This study showed that the communal area maintained comparable plant species richness and vegetation structure and composition to game farms. The rural landscape comprised a gradient from sites close to the village that were heavily impacted, not considered particularly special or sacred but safe, familiar and of utilitarian importance, to sites farther away with denser, less transformed thicket vegetation, which are considered to be of greater cultural, spiritual and aesthetic importance but less safe, familiar and accessible. This suggests that conservation outcomes can be achieved outside protected areas, and that biodiversity is valuable to local residents. Resource management should be implemented to maintain the ecosystem services provided in rural areas in a way that integrates local peoples’ perceptions, goals and values with ecological evidence.
- Full Text:
Perceptions and livelihood uses of an invasive alien tree (acacia dealbata) by rural communities in the Eastern Cape
- Authors: Agripa, Ngorima
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5326 , vital:20813
- Description: The negative impacts which invasive alien species have on ecosystems are well documented but there is paucity of information on their impacts on rural communities. Due to ecological impacts that may be associated with Acacia dealbata invasions the Agricultural Research Council Plant Protection Institute is considering releasing a biocontrol agent for A. dealbata. The actual social impacts of A. dealbata invasion and control are likely to be related to its importance in rural livelihoods. This thesis reports on the perceptions and livelihood uses of A. dealbata in the Eastern Cape. Three study sites were assessed, Matatiele, Mount Fletcher and Maclear. The study involved 150 household surveys, one focus group discussion and one transect walk at each site, key informant interviews and frequent house visits to acquire reliable data. Results show that 100 % of households in the three sites use Silver Wattle extensively for firewood. In Matatiele 64 %, 72 % in Mount Fletcher and 84 % of households in Maclear use Silver Wattle for fencing. To carve tools 76 % in Matatiele, 76 % in Mount Fletcher and 84 % households in Maclear use Silver Wattle. For medicinal purposes 18 % in Matatiele, 20 % in Mount Fletcher and 16 % in Maclear use Silver Wattle, whilst 78 % in Matatiele, 80 % in Mount Fletcher and 80 % in Maclear use it for fodder purposes. Many respondents felt that Silver Wattle is too abundant within their areas such that it now has many negative impacts associated with it. Perceptions of local people towards A. dealbata are neither static nor uniform, but are influenced by time since the invasion and now abundance of the species. There are no alternatives which provide the same services provided by Silver Wattle. Benefits and constraints due to A. dealbata invasion are experienced by everyone irrespective of wealth and gender. In conclusion, Silver Wattle is a valuable resource to these rural communities, but increasing abundance is incurring high costs to grazing resources and landscape accessibility.
- Full Text:
- Authors: Agripa, Ngorima
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5326 , vital:20813
- Description: The negative impacts which invasive alien species have on ecosystems are well documented but there is paucity of information on their impacts on rural communities. Due to ecological impacts that may be associated with Acacia dealbata invasions the Agricultural Research Council Plant Protection Institute is considering releasing a biocontrol agent for A. dealbata. The actual social impacts of A. dealbata invasion and control are likely to be related to its importance in rural livelihoods. This thesis reports on the perceptions and livelihood uses of A. dealbata in the Eastern Cape. Three study sites were assessed, Matatiele, Mount Fletcher and Maclear. The study involved 150 household surveys, one focus group discussion and one transect walk at each site, key informant interviews and frequent house visits to acquire reliable data. Results show that 100 % of households in the three sites use Silver Wattle extensively for firewood. In Matatiele 64 %, 72 % in Mount Fletcher and 84 % of households in Maclear use Silver Wattle for fencing. To carve tools 76 % in Matatiele, 76 % in Mount Fletcher and 84 % households in Maclear use Silver Wattle. For medicinal purposes 18 % in Matatiele, 20 % in Mount Fletcher and 16 % in Maclear use Silver Wattle, whilst 78 % in Matatiele, 80 % in Mount Fletcher and 80 % in Maclear use it for fodder purposes. Many respondents felt that Silver Wattle is too abundant within their areas such that it now has many negative impacts associated with it. Perceptions of local people towards A. dealbata are neither static nor uniform, but are influenced by time since the invasion and now abundance of the species. There are no alternatives which provide the same services provided by Silver Wattle. Benefits and constraints due to A. dealbata invasion are experienced by everyone irrespective of wealth and gender. In conclusion, Silver Wattle is a valuable resource to these rural communities, but increasing abundance is incurring high costs to grazing resources and landscape accessibility.
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Phenomenology: preconceptions and experiences of non-chemists at Rhodes University using milk paint
- Authors: Kelly, Kelvin Leigh
- Date: 2017
- Subjects: Phenomenology , Art and science , Casein , Paint , Chemistry -- Study and teaching , Science -- Study and teaching -- Philosophy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/37942 , vital:24711
- Description: There exists an ever-increasing crisis in science education where students experience disinterest because of an inability to grasp true understanding of scientific subjects, and therefore there should be a call to increase the research of phenomenology in combination with science education. A rebalance and paradigm shift in the focus of the modes of teaching could result in a great improvement in the learning, comprehension, and intellectual self-confidence of students interested in the sciences. To study this, three research questions were established: How is chemistry perceived by non-chemists; what is the experience of the participants’ during the chemistry practical in a laboratory and; do the participants’ perspectives about chemistry change during the experience. The performed study consisted of a chemistry practical, two art works and, in some cases, an interview. Nine participants were asked to create the art under specific instructions of points of focus, namely their preconceptions prior to the practical (Artwork 1) and their lived experience during the practical (Artwork 2). Participants’ artworks were examined using methods of visual semiotics and classical art analysis techniques, looking at line, shape, and colour choice. The iterative analysis of the interviews from participants 1, 2, 7, and 9 coded with ATLAS.ti 7 software, led to the emergence of themes that constitute the core of the participants’ experience. This phenomenological study presents a path to engage the non-chemist with processes taking place in the laboratory by using ‘Kitchen Chemistry’ and illustrates how a phenomenological engagement with chemistry can make the subject more applicable to the general population of non-chemists.
- Full Text:
- Authors: Kelly, Kelvin Leigh
- Date: 2017
- Subjects: Phenomenology , Art and science , Casein , Paint , Chemistry -- Study and teaching , Science -- Study and teaching -- Philosophy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/37942 , vital:24711
- Description: There exists an ever-increasing crisis in science education where students experience disinterest because of an inability to grasp true understanding of scientific subjects, and therefore there should be a call to increase the research of phenomenology in combination with science education. A rebalance and paradigm shift in the focus of the modes of teaching could result in a great improvement in the learning, comprehension, and intellectual self-confidence of students interested in the sciences. To study this, three research questions were established: How is chemistry perceived by non-chemists; what is the experience of the participants’ during the chemistry practical in a laboratory and; do the participants’ perspectives about chemistry change during the experience. The performed study consisted of a chemistry practical, two art works and, in some cases, an interview. Nine participants were asked to create the art under specific instructions of points of focus, namely their preconceptions prior to the practical (Artwork 1) and their lived experience during the practical (Artwork 2). Participants’ artworks were examined using methods of visual semiotics and classical art analysis techniques, looking at line, shape, and colour choice. The iterative analysis of the interviews from participants 1, 2, 7, and 9 coded with ATLAS.ti 7 software, led to the emergence of themes that constitute the core of the participants’ experience. This phenomenological study presents a path to engage the non-chemist with processes taking place in the laboratory by using ‘Kitchen Chemistry’ and illustrates how a phenomenological engagement with chemistry can make the subject more applicable to the general population of non-chemists.
- Full Text:
Photophysical studies of conjugates of upconversion nanoparticles with aluminium phthalocyanines
- Authors: Watkins, Zane
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4964 , vital:20747
- Description: NaYF4 :Yb/Er/Gd upconversion nanoparticles (UCNP) were synthesised and their photoemission stabilised by embedding these nanoparticles in electrospun fibres. The photophysical behaviour of chloro aluminium tetrasulfo-phthalocyanine chloride (ClAlTSPc) was studied in the presence of UCNPs on mixing the two species in solution. The fluorescence lifetimes for UCNPs were shortened at 658 nm in the presence of ClAlTSPc when the former was embedded in fibre and suspended in a dimethyl sulfoxide solution of the latter. A clear singlet oxygen generation by ClAlTSPc through Forster resonance energy transfer (FRET) was demonstrated using a singlet oxygen quencher, 1,3-diphenylisobenzofuran. UCNP capped with amino groups were then covalently attached to chloro aluminium tetrasulphonated phthalocyanine (ClAlTSPc) and chloro aluminium tetracarboxy phthalocyanine (ClAlTCPc). The conjugates were characterized using different techniques such as infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS) and Transmission electron microscopy (TEM). There was a decrease in fluorescence emission spectra of the UCNPs at 658 nm in the presence of the phthalocyanines. This decrease indicates an energy transfer between the donor UCNP and conjugated accepting phthalocyanine (Pc), due to FRET. Low FRET efficiencies of 18 and 21 % for ClAlTSPc and ClAlTCPc, respectively, were obtained.
- Full Text:
- Authors: Watkins, Zane
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4964 , vital:20747
- Description: NaYF4 :Yb/Er/Gd upconversion nanoparticles (UCNP) were synthesised and their photoemission stabilised by embedding these nanoparticles in electrospun fibres. The photophysical behaviour of chloro aluminium tetrasulfo-phthalocyanine chloride (ClAlTSPc) was studied in the presence of UCNPs on mixing the two species in solution. The fluorescence lifetimes for UCNPs were shortened at 658 nm in the presence of ClAlTSPc when the former was embedded in fibre and suspended in a dimethyl sulfoxide solution of the latter. A clear singlet oxygen generation by ClAlTSPc through Forster resonance energy transfer (FRET) was demonstrated using a singlet oxygen quencher, 1,3-diphenylisobenzofuran. UCNP capped with amino groups were then covalently attached to chloro aluminium tetrasulphonated phthalocyanine (ClAlTSPc) and chloro aluminium tetracarboxy phthalocyanine (ClAlTCPc). The conjugates were characterized using different techniques such as infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS) and Transmission electron microscopy (TEM). There was a decrease in fluorescence emission spectra of the UCNPs at 658 nm in the presence of the phthalocyanines. This decrease indicates an energy transfer between the donor UCNP and conjugated accepting phthalocyanine (Pc), due to FRET. Low FRET efficiencies of 18 and 21 % for ClAlTSPc and ClAlTCPc, respectively, were obtained.
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Photosynthetic and growth responses of C3 and C4 grasses to short- duration sunflecks and resultant consequences for their performance in understory environments
- Authors: Adams, Claire Elizabeth
- Date: 2017
- Subjects: Understory plants -- Effect of light on , Grasses -- Effect of light on -- South Africa , Erharta -- Effect of light on , Brachiara -- Effect of light on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5016 , vital:20753
- Description: Low C4 grass species abundance in understory environments is thought to be as a result of their high-light requirements, lack of photosynthetic advantage relative to C3 species in cooler environments, and an inability to adequately utilise sunflecks. This study sets out to investigate this theory, hypothesizing that C3 grass species outperform C4 grass species under the canopy, not as a result of quantum efficiency temperature effects, but as a result of C4 species inability to utilize short-duration sunflecks. Short sunflecks could result in a breakdown in assimilate movement between the mesophyll (MSC) and bundle sheath (BSC) cells. The role of BSC leakiness, stomata and PSII efficiency on the ability of C3 and C4 Alloteropsis semialata to utilize short-duration sunflecks was investigated using gaseous exchange and chlorophyll fluorescence techniques, while the growth of both subspecies under a simulated flecking-light environment tested whether these measured responses translated into effects on growth. As C3 grasses are known to possess higher levels of stomatal conductance in relation to C4 species, results showed that C3 A. semialata was able to utilize short-duration sunflecks as a result of increased stomatal conductance and an ability to induce photosynthesis under various light flecking conditions. In contrast, C4 A. semialata was unable to utilize sunflecks possibly as a result of energetic limitations of the carboxylation mechanism (PSII) and not because of increased bundle sheath leakiness. These photosynthetic responses translated into growth differences when both types were grown in an artificially flecking light environment. The photosynthetic differences noted for C3 and C4 A.semialata were also evident in shade adapted understory grasses; Erharta erecta (C3), Dactylotenium australe (C4) and Brachiaria chusqueoides (C4). As photosynthetic induction was marginally more rapid in all species relative to A. semialata it suggests some degree of adaptation in shade grasses, however the inability of the C4 species to utilise short sunflecks remained. As a result, it was hypothesized that C3 shade adapted E. erecta and C4 B. chusqueoides, co-inhabiting the same forest understory, are able to do so because of differences in light micro-environments associated with each species. However, canopy openness and light profiles determined for theses micro-climates showed no differences and that both species have persisted within a relatively stable understory environment. The coexistence was possible as the understory was supplied with a significant proportion of its daily light in flecks sufficiently long as to not compromise C4 productivity. A survey of 10 species of grasses under various canopy densities and in the open showed a strong negative linear relationship between canopy openness and the rate at which photosynthesis was induced by flecking light, which has not been shown before. This did not result from the phylogenetic relationship between species and could be shown for a single species (E. erecta) growing in a range of light environments. This demonstrates that C4 grasses, despite adaptation, would be limited from sunfleck environments if a significant proportion of the daily light available consists of flecks of short-duration. The generation of such environments may occur as a result of woody thickening and could help explain the observed decline in C4 grasses under these conditions.
- Full Text:
- Authors: Adams, Claire Elizabeth
- Date: 2017
- Subjects: Understory plants -- Effect of light on , Grasses -- Effect of light on -- South Africa , Erharta -- Effect of light on , Brachiara -- Effect of light on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5016 , vital:20753
- Description: Low C4 grass species abundance in understory environments is thought to be as a result of their high-light requirements, lack of photosynthetic advantage relative to C3 species in cooler environments, and an inability to adequately utilise sunflecks. This study sets out to investigate this theory, hypothesizing that C3 grass species outperform C4 grass species under the canopy, not as a result of quantum efficiency temperature effects, but as a result of C4 species inability to utilize short-duration sunflecks. Short sunflecks could result in a breakdown in assimilate movement between the mesophyll (MSC) and bundle sheath (BSC) cells. The role of BSC leakiness, stomata and PSII efficiency on the ability of C3 and C4 Alloteropsis semialata to utilize short-duration sunflecks was investigated using gaseous exchange and chlorophyll fluorescence techniques, while the growth of both subspecies under a simulated flecking-light environment tested whether these measured responses translated into effects on growth. As C3 grasses are known to possess higher levels of stomatal conductance in relation to C4 species, results showed that C3 A. semialata was able to utilize short-duration sunflecks as a result of increased stomatal conductance and an ability to induce photosynthesis under various light flecking conditions. In contrast, C4 A. semialata was unable to utilize sunflecks possibly as a result of energetic limitations of the carboxylation mechanism (PSII) and not because of increased bundle sheath leakiness. These photosynthetic responses translated into growth differences when both types were grown in an artificially flecking light environment. The photosynthetic differences noted for C3 and C4 A.semialata were also evident in shade adapted understory grasses; Erharta erecta (C3), Dactylotenium australe (C4) and Brachiaria chusqueoides (C4). As photosynthetic induction was marginally more rapid in all species relative to A. semialata it suggests some degree of adaptation in shade grasses, however the inability of the C4 species to utilise short sunflecks remained. As a result, it was hypothesized that C3 shade adapted E. erecta and C4 B. chusqueoides, co-inhabiting the same forest understory, are able to do so because of differences in light micro-environments associated with each species. However, canopy openness and light profiles determined for theses micro-climates showed no differences and that both species have persisted within a relatively stable understory environment. The coexistence was possible as the understory was supplied with a significant proportion of its daily light in flecks sufficiently long as to not compromise C4 productivity. A survey of 10 species of grasses under various canopy densities and in the open showed a strong negative linear relationship between canopy openness and the rate at which photosynthesis was induced by flecking light, which has not been shown before. This did not result from the phylogenetic relationship between species and could be shown for a single species (E. erecta) growing in a range of light environments. This demonstrates that C4 grasses, despite adaptation, would be limited from sunfleck environments if a significant proportion of the daily light available consists of flecks of short-duration. The generation of such environments may occur as a result of woody thickening and could help explain the observed decline in C4 grasses under these conditions.
- Full Text:
Political correctness and freedom of expression
- Authors: Embling, Geoffrey
- Date: 2017
- Subjects: Political correctness , Freedom of speech , Political correctness -- South Africa , Freedom of speech -- South Africa , Censorship , Censorship -- South Africa , South Africa -- Politics and government , Political satire, South African , Fanatacism , Toleration
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/40873 , vital:25035
- Description: A brief history of political correctness is discussed along with various definitions of it, ranging from political correctness being a benign attempt to prevent offense and avert discrimination to stronger views equating it with Communist censorship or branding it as "cultural Marxism". The aim of the research is to discover what political correctness is, how it relates to freedom of expression and what wider implications and effects it has on society. The moral foundations of rights and free speech in particular are introduced in order to set a framework to determine what authority people and governments have to censor others' expression. Different philosophical views on the limits of free speech are discussed, and arguments for and against hate speech are analysed and related to political correctness. The thesis looks at political correctness on university campuses, which involves speech codes, antidiscrimination legislation and changing the Western canon to a more multicultural syllabus. The recent South African university protests involving issues such as white privilege, university fees and rape are discussed and related to political correctness. The thesis examines the role of political correctness in the censorship of humour, it discusses the historical role of satire in challenging dogmatism and it looks at the psychology behind intolerance. Political correctness appeals to tolerance, which is sometimes elevated at the expense of truth. Truth and tolerance are therefore weighed up, along with their altered definitions in today's relativistic society. The last part of the thesis looks at South Africa's unique brand of political correctness, along with Black Economic Empowerment, colonialism and white guilt, and the research concludes that political correctness is a distinct form of censorship which has developed in modern democracies. The new forms of justice and morality seen in political correctness are distortions of left-wing liberalism, which appeal to different values to those of traditional liberalism.
- Full Text:
- Authors: Embling, Geoffrey
- Date: 2017
- Subjects: Political correctness , Freedom of speech , Political correctness -- South Africa , Freedom of speech -- South Africa , Censorship , Censorship -- South Africa , South Africa -- Politics and government , Political satire, South African , Fanatacism , Toleration
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/40873 , vital:25035
- Description: A brief history of political correctness is discussed along with various definitions of it, ranging from political correctness being a benign attempt to prevent offense and avert discrimination to stronger views equating it with Communist censorship or branding it as "cultural Marxism". The aim of the research is to discover what political correctness is, how it relates to freedom of expression and what wider implications and effects it has on society. The moral foundations of rights and free speech in particular are introduced in order to set a framework to determine what authority people and governments have to censor others' expression. Different philosophical views on the limits of free speech are discussed, and arguments for and against hate speech are analysed and related to political correctness. The thesis looks at political correctness on university campuses, which involves speech codes, antidiscrimination legislation and changing the Western canon to a more multicultural syllabus. The recent South African university protests involving issues such as white privilege, university fees and rape are discussed and related to political correctness. The thesis examines the role of political correctness in the censorship of humour, it discusses the historical role of satire in challenging dogmatism and it looks at the psychology behind intolerance. Political correctness appeals to tolerance, which is sometimes elevated at the expense of truth. Truth and tolerance are therefore weighed up, along with their altered definitions in today's relativistic society. The last part of the thesis looks at South Africa's unique brand of political correctness, along with Black Economic Empowerment, colonialism and white guilt, and the research concludes that political correctness is a distinct form of censorship which has developed in modern democracies. The new forms of justice and morality seen in political correctness are distortions of left-wing liberalism, which appeal to different values to those of traditional liberalism.
- Full Text:
Population genomics analysis of yellowfin tuna Thunnus albacares off South Africa reveals need for a shifted management boundary
- Authors: Mullins, Rachel Brenna
- Date: 2017
- Subjects: Yellowfin tuna fisheries -- South Africa -- Western Cape , Genomics , Tuna fisheries -- South Africa , Fishery management -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/57819 , vital:26992
- Description: Yellowfin tuna Thunnus albacares is a commercially and economically important fisheries species, which comprises the second largest component of South Africa’s catch of tuna and tuna-like species. Catches of the species off South Africa are treated as two discrete stocks by the two tuna Regional Fisheries Management Organisations (tRFMOs) under whose jurisdictions they fall. Individuals caught off the Western Cape, west of the boundary between the tRFMOs at 20°E, are included in assessment and management of the Atlantic Ocean yellowfin tuna stock by the International Commission for the Conservation of Atlantic Tunas (ICCAT), and those caught east of this boundary are assessed and managed as part of the Indian Ocean stock by the Indian Ocean Tuna Commission (IOTC). The boundary between these stocks is based on the confluence of the two oceans in this region and does not incorporate the population structure of species. For sustainable exploitation of fisheries resources, it is important that the definition of management stocks reflects species’ biological population structure; the fine-scale stock structure of yellowfin tuna off South Africa is therefore a research priority which this study aimed to address by means of population genomics analyses. Yellowfin tuna exhibit shallow genetic differentiation over wide geographic areas, and as such traditional population genetic approaches have limited power in resolving fishery significant population structure in the species. Herein, a population genomic approach was employed, specifically, genome-wide analysis of single nucleotide polymorphisms (SNPs) discovered using a next-generation DNA sequencing approach, to confer (i) increased statistical power to detect neutral structuring reflecting population connectivity patterns and (ii) signatures of local adaptation. The mitochondrial Control Region (mtDNA CR) was also sequenced to compare the resolving power of different approaches and to permit coalescent based analyses of the species evolutionary history in the region. Neutral SNP loci revealed significant structure within the dataset (Fst=0.0043; P<0.0001); partitioning of this differentiation within the dataset indicated significant differentiation between yellowfin tuna from the Western Cape and the Gulf of Guinea in the eastern Atlantic Ocean, with no significant differentiation between individuals from the Western Cape and Western Indian Ocean regions. This indicates two population units wherein there is a separation of the Gulf of Guinea from the remaining samples (Indian Ocean including Western Cape) that are largely derived from a single genetic population. This pattern was also supported by assignment tests. Positive outlier SNPs, exhibiting signatures of diversifying selection, suggest that individuals from these regions may be locally adapted, as well as demographically isolated. The mtDNA CR did not reveal any significant genetic structure among samples (Fst=0.0030; P=0.309), demonstrating the increased resolving power provided by population genomics approaches, but revealed signatures of historical demographic fluctuations associated with glacial cycles. Based on the findings of this study, it is suggested that yellowfin tuna caught off the Western Cape of South Africa are migrants from the Indian Ocean population, exhibiting significant genetic differentiation from the Atlantic Ocean Gulf of Guinea individuals, and should thus be included in the assessment and management of the Indian Ocean stock. It is therefore recommended that the boundary between the Atlantic and Indian Ocean yellowfin tuna stocks, under the mandates of ICCAT and the IOTC respectively, should be shifted to approximately 13.35°E to include all individuals caught in South African waters in the Indian Ocean stock.
- Full Text:
- Authors: Mullins, Rachel Brenna
- Date: 2017
- Subjects: Yellowfin tuna fisheries -- South Africa -- Western Cape , Genomics , Tuna fisheries -- South Africa , Fishery management -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/57819 , vital:26992
- Description: Yellowfin tuna Thunnus albacares is a commercially and economically important fisheries species, which comprises the second largest component of South Africa’s catch of tuna and tuna-like species. Catches of the species off South Africa are treated as two discrete stocks by the two tuna Regional Fisheries Management Organisations (tRFMOs) under whose jurisdictions they fall. Individuals caught off the Western Cape, west of the boundary between the tRFMOs at 20°E, are included in assessment and management of the Atlantic Ocean yellowfin tuna stock by the International Commission for the Conservation of Atlantic Tunas (ICCAT), and those caught east of this boundary are assessed and managed as part of the Indian Ocean stock by the Indian Ocean Tuna Commission (IOTC). The boundary between these stocks is based on the confluence of the two oceans in this region and does not incorporate the population structure of species. For sustainable exploitation of fisheries resources, it is important that the definition of management stocks reflects species’ biological population structure; the fine-scale stock structure of yellowfin tuna off South Africa is therefore a research priority which this study aimed to address by means of population genomics analyses. Yellowfin tuna exhibit shallow genetic differentiation over wide geographic areas, and as such traditional population genetic approaches have limited power in resolving fishery significant population structure in the species. Herein, a population genomic approach was employed, specifically, genome-wide analysis of single nucleotide polymorphisms (SNPs) discovered using a next-generation DNA sequencing approach, to confer (i) increased statistical power to detect neutral structuring reflecting population connectivity patterns and (ii) signatures of local adaptation. The mitochondrial Control Region (mtDNA CR) was also sequenced to compare the resolving power of different approaches and to permit coalescent based analyses of the species evolutionary history in the region. Neutral SNP loci revealed significant structure within the dataset (Fst=0.0043; P<0.0001); partitioning of this differentiation within the dataset indicated significant differentiation between yellowfin tuna from the Western Cape and the Gulf of Guinea in the eastern Atlantic Ocean, with no significant differentiation between individuals from the Western Cape and Western Indian Ocean regions. This indicates two population units wherein there is a separation of the Gulf of Guinea from the remaining samples (Indian Ocean including Western Cape) that are largely derived from a single genetic population. This pattern was also supported by assignment tests. Positive outlier SNPs, exhibiting signatures of diversifying selection, suggest that individuals from these regions may be locally adapted, as well as demographically isolated. The mtDNA CR did not reveal any significant genetic structure among samples (Fst=0.0030; P=0.309), demonstrating the increased resolving power provided by population genomics approaches, but revealed signatures of historical demographic fluctuations associated with glacial cycles. Based on the findings of this study, it is suggested that yellowfin tuna caught off the Western Cape of South Africa are migrants from the Indian Ocean population, exhibiting significant genetic differentiation from the Atlantic Ocean Gulf of Guinea individuals, and should thus be included in the assessment and management of the Indian Ocean stock. It is therefore recommended that the boundary between the Atlantic and Indian Ocean yellowfin tuna stocks, under the mandates of ICCAT and the IOTC respectively, should be shifted to approximately 13.35°E to include all individuals caught in South African waters in the Indian Ocean stock.
- Full Text:
Positioning 'the self': comparative case studies of first generation students' academic identities when home meets campus in a rapidly transforming higher education context
- Authors: Alcock, Andrea
- Date: 2017
- Subjects: First-generation college students -- South Africa , First-generation college students -- South Africa -- Case studies , Social perception -- South Africa , Educational equalization -- South Africa , College students -- South Africa -- Attitudes , College students, Black -- South Africa -- Attitudes , College students, Black -- South Africa -- Psychology
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/6897 , vital:21198
- Description: This research offers an in-depth view of the self-positioning of a sample of seven first generation students in an extended curriculum programme for Arts and Design at the Durban University of Technology. This comparative case study aims to examine how these participants took up, held or resisted positions, during the transitional process of entering a university. The students' responses were elicited in order to explore the development of student academic identity in this stage of late adolescence. Using positioning theory as an analytical framework, a visual methodology was employed to generate data during photo-elicitation interviews. For these, participants were invited to take metaphorical and non-mimetic photographs, in response to the prompt "Take photographs that show you as a student at home and on campus". Themes that surfaced were examined using positioning theory where the storylines, speech acts and rights and duties form the apex points of the positioning triangle that acts as a framework to analyse the participants' narratives. The study revealed the ways in which participants positioned their home communities and thereby developed their own agency. The majority of the participants used their self-positioning in relation to these home communities to build their academic identities. It was evident in the data that certain role models and peers played a significant part in such self-positioning. The rural to urban migration described by some of the participants indicated that the transition students navigated as they developed their academic identities was profound. The university was often perceived in this process as a powerful structure which offered opportunities but could simultaneously be experienced as alienating. Financial challenges added to the complexity of this experience. The development of student academic identity was evident in positioning statements of the participants and, in some cases, a professional identity was revealed. The analysis indicated that the participants were able to use their self-positioning to overcome many of their challenges through the creation of agential power and resilience. Furthermore the emergence of academic identity seemed to give rise to a positive view of 'the self' in relation to the period of transition to university.
- Full Text:
- Authors: Alcock, Andrea
- Date: 2017
- Subjects: First-generation college students -- South Africa , First-generation college students -- South Africa -- Case studies , Social perception -- South Africa , Educational equalization -- South Africa , College students -- South Africa -- Attitudes , College students, Black -- South Africa -- Attitudes , College students, Black -- South Africa -- Psychology
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/6897 , vital:21198
- Description: This research offers an in-depth view of the self-positioning of a sample of seven first generation students in an extended curriculum programme for Arts and Design at the Durban University of Technology. This comparative case study aims to examine how these participants took up, held or resisted positions, during the transitional process of entering a university. The students' responses were elicited in order to explore the development of student academic identity in this stage of late adolescence. Using positioning theory as an analytical framework, a visual methodology was employed to generate data during photo-elicitation interviews. For these, participants were invited to take metaphorical and non-mimetic photographs, in response to the prompt "Take photographs that show you as a student at home and on campus". Themes that surfaced were examined using positioning theory where the storylines, speech acts and rights and duties form the apex points of the positioning triangle that acts as a framework to analyse the participants' narratives. The study revealed the ways in which participants positioned their home communities and thereby developed their own agency. The majority of the participants used their self-positioning in relation to these home communities to build their academic identities. It was evident in the data that certain role models and peers played a significant part in such self-positioning. The rural to urban migration described by some of the participants indicated that the transition students navigated as they developed their academic identities was profound. The university was often perceived in this process as a powerful structure which offered opportunities but could simultaneously be experienced as alienating. Financial challenges added to the complexity of this experience. The development of student academic identity was evident in positioning statements of the participants and, in some cases, a professional identity was revealed. The analysis indicated that the participants were able to use their self-positioning to overcome many of their challenges through the creation of agential power and resilience. Furthermore the emergence of academic identity seemed to give rise to a positive view of 'the self' in relation to the period of transition to university.
- Full Text:
Post-release evaluation and thermal physiology of the Pereskia stem-wilter, Catorhintha schaffneri (Coreidae), a new biological control agent for Pereskia aculeata (Cactaceae)
- Authors: Muskett, Phillippa Claire
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/36094 , vital:24477
- Description: Catorhintha schaffneri Brailovsky and Garcia (Hemiptera: Coreidae) is a biological control agent that was recently accepted for release in South Africa to control Pereskia aculeata Miller (Cactaceae), an invasive creeping cactus. The aim of this thesis was to conduct post-release research to ensure that C. schaffneri is utilised to its full potential. To achieve this aim, and focus release efforts, the thermal physiology of C. schaffneri was investigated to predict where in South Africa the agent is most likely to establish. These predictions were then tested by releasing the agent at field sites with a wide variety of climatic conditions and evaluating establishment success. When invasive plants invade a wide distribution, made up of areas with different climatic conditions, biological control agents may not establish or be effective throughout the invaded distribution. According to the thermal physiology of C. schaffneri, it is most likely to establish and become effective in the subtropical region of South Africa, along the coast of KwaZulu- Natal. Cold winters, or generally low year-round temperatures, may limit establishment in the more temperate areas of South Africa in the Eastern and Western Cape as well as inland in the Highveld region. These predictions can be used to focus release efforts to climatically suitable regions and stop releases in areas where C. schaffneri cannot survive. Predictions based on thermal physiology may not account for all of the variables which affect establishment. To account for other variables, the establishment of C. schaffneri was tested using closely monitored field release studies. During these studies the effect of other variables such as; microclimate temperature, humidity, precipitation, plant quality and release strategy were considered. Low humidity, precipitation and plant quality appear to affect the establishment of C. schaffneri in the subtropical areas of South Africa. The experiment was conducted during a period of drought, and this may have resulted in lower establishment rates. The most successful release strategy for C. schaffneri was the use of multiple, small releases rather than single releases of the same number of individuals. The field based study was therefore able to improve the biological control of P. aculeata by increasing the chance that each release of C. schaffneri results in establishment. The post-release studies presented in this thesis will increase the impact of C. schaffneri by focussing release efforts to climatically suitable sites, releasing at appropriate times of year and releasing the agent in a manner that increases establishment success. Post-release studies, such as those presented here, can make biological control programmes more efficient and effective.
- Full Text:
- Authors: Muskett, Phillippa Claire
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/36094 , vital:24477
- Description: Catorhintha schaffneri Brailovsky and Garcia (Hemiptera: Coreidae) is a biological control agent that was recently accepted for release in South Africa to control Pereskia aculeata Miller (Cactaceae), an invasive creeping cactus. The aim of this thesis was to conduct post-release research to ensure that C. schaffneri is utilised to its full potential. To achieve this aim, and focus release efforts, the thermal physiology of C. schaffneri was investigated to predict where in South Africa the agent is most likely to establish. These predictions were then tested by releasing the agent at field sites with a wide variety of climatic conditions and evaluating establishment success. When invasive plants invade a wide distribution, made up of areas with different climatic conditions, biological control agents may not establish or be effective throughout the invaded distribution. According to the thermal physiology of C. schaffneri, it is most likely to establish and become effective in the subtropical region of South Africa, along the coast of KwaZulu- Natal. Cold winters, or generally low year-round temperatures, may limit establishment in the more temperate areas of South Africa in the Eastern and Western Cape as well as inland in the Highveld region. These predictions can be used to focus release efforts to climatically suitable regions and stop releases in areas where C. schaffneri cannot survive. Predictions based on thermal physiology may not account for all of the variables which affect establishment. To account for other variables, the establishment of C. schaffneri was tested using closely monitored field release studies. During these studies the effect of other variables such as; microclimate temperature, humidity, precipitation, plant quality and release strategy were considered. Low humidity, precipitation and plant quality appear to affect the establishment of C. schaffneri in the subtropical areas of South Africa. The experiment was conducted during a period of drought, and this may have resulted in lower establishment rates. The most successful release strategy for C. schaffneri was the use of multiple, small releases rather than single releases of the same number of individuals. The field based study was therefore able to improve the biological control of P. aculeata by increasing the chance that each release of C. schaffneri results in establishment. The post-release studies presented in this thesis will increase the impact of C. schaffneri by focussing release efforts to climatically suitable sites, releasing at appropriate times of year and releasing the agent in a manner that increases establishment success. Post-release studies, such as those presented here, can make biological control programmes more efficient and effective.
- Full Text:
Post-release evaluation of the biological control programme against Cereus jamacaru De Candolle (Cactaceae), in South Africa
- Authors: Sutton, Guy Frederick
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7982 , vital:21330
- Description: Cereus jamacaru De Candolle (Cactaceae) is an environment-transforming weed of both agricultural and wildlife habitats in South Africa. Weed infestations reduce carrying capacity of the land, and pose a risk to livestock, wildlife and human safety due to the plant’s spiny thorns. The weed is considered to be under complete biological control in South Africa, due to its introduced control agent, Hypogeococcus festerianus Lizer y Trelles (Hemiptera: Pseudococcidae), although observational reports suggest that the level of success achieved is variable. In this thesis, a formal post-release evaluation of this biological control programme was conducted, specifically to determine the efficacy of H. festerianus as a biological control agent, and to identify factors which may limit or constrain the level of success achieved by the control agent. These data were collected with the intention of improving the control of C. jamacaru in South Africa. A field-based study of C. jamacaru population demographics investigated the efficacy of H. festerianus as a biological control agent of the weed, by integrating weed growth, fecundity and survival metrics with C. jamacaru population dynamics and demographic patterns from 8 sites where H. festerianus was present and 14 sites where the control agent was absent. The findings indicated that H. festerianus significantly reduced weed fecundity, which resulted in fewer seedling recruits, and that levels of plant mortality were greater at sites where H. festerianus was present. The reduction in weed fecundity and survival translated into negative population-level consequences for H. festerianus. Weed-population age frequency distributions in the absence of H. festerianus demonstrated a “reverse J-shaped” distribution, indicative of high recruitment rates and population stability, while C. jamacaru populations infected with H. festerianus were described by bell-shaped distributions, and were typified by limited recruitment, or a complete lack thereof. By constraining recruitment and inhibiting selfregeneration, H. festerianus appears to regulate populations of C. jamacaru. Predation and parasitism of H. festerianus was believed to be a limiting factor for the biological control programme against C. jamacaru in South Africa, although no formal evaluation of this claim had been undertaken. Accordingly, the assemblage of natural enemies acquired by H. festerianus in South Africa was identified by field-collections of infected H. festerianus gall-material. Further, timed point-count surveys of natural enemies associated with H. festerianus were performed and integrated with the data on the impact of H. festerianus on weed population dynamics to assess the impact of two prominent predaceous taxa on H. festerianus efficacy as a biological control agent. Although H. festerianus had acquired a diverse suite of novel natural enemies in South Africa, this has not prevented the biocontrol agent from having an impact on C. jamacaru populations, although other subtler effects cannot be ruled out. This study showed that biological control efforts employing H. festerianus for the management of C. jamacaru have been successful. Furthermore, these data demonstrated the utility of retrospective analyses in developing and improving the science of biological control, specifically how to improve candidate agent prioritisation, determining how many agents are required for successful biological control, and how to evaluate the success of biological control efforts. Improvements in our theoretical understanding of biological control will undoubtedly reduce costs of biological control programmes, improve success rates, and increase the predictability of biological control.
- Full Text:
- Authors: Sutton, Guy Frederick
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7982 , vital:21330
- Description: Cereus jamacaru De Candolle (Cactaceae) is an environment-transforming weed of both agricultural and wildlife habitats in South Africa. Weed infestations reduce carrying capacity of the land, and pose a risk to livestock, wildlife and human safety due to the plant’s spiny thorns. The weed is considered to be under complete biological control in South Africa, due to its introduced control agent, Hypogeococcus festerianus Lizer y Trelles (Hemiptera: Pseudococcidae), although observational reports suggest that the level of success achieved is variable. In this thesis, a formal post-release evaluation of this biological control programme was conducted, specifically to determine the efficacy of H. festerianus as a biological control agent, and to identify factors which may limit or constrain the level of success achieved by the control agent. These data were collected with the intention of improving the control of C. jamacaru in South Africa. A field-based study of C. jamacaru population demographics investigated the efficacy of H. festerianus as a biological control agent of the weed, by integrating weed growth, fecundity and survival metrics with C. jamacaru population dynamics and demographic patterns from 8 sites where H. festerianus was present and 14 sites where the control agent was absent. The findings indicated that H. festerianus significantly reduced weed fecundity, which resulted in fewer seedling recruits, and that levels of plant mortality were greater at sites where H. festerianus was present. The reduction in weed fecundity and survival translated into negative population-level consequences for H. festerianus. Weed-population age frequency distributions in the absence of H. festerianus demonstrated a “reverse J-shaped” distribution, indicative of high recruitment rates and population stability, while C. jamacaru populations infected with H. festerianus were described by bell-shaped distributions, and were typified by limited recruitment, or a complete lack thereof. By constraining recruitment and inhibiting selfregeneration, H. festerianus appears to regulate populations of C. jamacaru. Predation and parasitism of H. festerianus was believed to be a limiting factor for the biological control programme against C. jamacaru in South Africa, although no formal evaluation of this claim had been undertaken. Accordingly, the assemblage of natural enemies acquired by H. festerianus in South Africa was identified by field-collections of infected H. festerianus gall-material. Further, timed point-count surveys of natural enemies associated with H. festerianus were performed and integrated with the data on the impact of H. festerianus on weed population dynamics to assess the impact of two prominent predaceous taxa on H. festerianus efficacy as a biological control agent. Although H. festerianus had acquired a diverse suite of novel natural enemies in South Africa, this has not prevented the biocontrol agent from having an impact on C. jamacaru populations, although other subtler effects cannot be ruled out. This study showed that biological control efforts employing H. festerianus for the management of C. jamacaru have been successful. Furthermore, these data demonstrated the utility of retrospective analyses in developing and improving the science of biological control, specifically how to improve candidate agent prioritisation, determining how many agents are required for successful biological control, and how to evaluate the success of biological control efforts. Improvements in our theoretical understanding of biological control will undoubtedly reduce costs of biological control programmes, improve success rates, and increase the predictability of biological control.
- Full Text:
Preparation and evaluation of captopril - ion exchange resin complexes
- Chikukwa, Mellisa Tafadzwa Ruramai
- Authors: Chikukwa, Mellisa Tafadzwa Ruramai
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59146 , vital:27441
- Description: Restricted access-thesis embargoed for 2 years
- Full Text:
- Authors: Chikukwa, Mellisa Tafadzwa Ruramai
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59146 , vital:27441
- Description: Restricted access-thesis embargoed for 2 years
- Full Text:
Producing journalism about climate change for news and agricultural radio: a case study of Malawi's public broadcaster
- Authors: Kapiri, Francis
- Date: 2017
- Subjects: Public radio -- Malawi , Climatic changes in mass media , Climatic changes in mass media -- Case studies -- Malawi , Radio in agriculture -- Malawi , Malawi Broadcasting Corporation
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/6375 , vital:21100
- Description: This study investigates how radio journalists at the Malawian public broadcaster (MBC) experience the task of producing content that can help their audiences to engage with the local relevance of climate change. This study establishes terms of reference for this research by mapping out international histories of public engagement with the concept of climate change in the domains of science, politics and the media. It describes how contestations around climate change have evolved within these spheres and concludes that such contestation is shaped by relations of power that inform the international economic domain. The study then examines scholarly evaluations of journalism about climate change, concluding that such evaluation is grounded in distinct normative understandings of the social purpose of such journalism. It is argued that research about Malawian journalists’ experience of reporting on climate change should draw on knowledge of the role that norms play within this local environment. With this goal in mind, the study reviews tools for the analysis of the normative foundations of journalism within specific socio-historic contexts. It demonstrates the relevance of these tools for the identification of norms and their influence on journalism about climate change in the Malawian context. The empirical component of the study draws on this framework by means of a case study of the experiences of journalists working at the MBC. It examines how these journalists experience the task of producing content that enables their audiences to engage with the local relevance of climate change. It compares such experience as articulated by journalists working for agricultural and news programming. It is concluded that the participants have access to credible knowledge about climate change and its relevance to the Malawian context. Based on such knowledge, they articulate a shared understanding of climate change and its relevance to the Malawian context. However, the study identifies differences in the way that the two groups make sense of the practice of producing journalism about climate change that is of relevance to their audience. In particular, the agricultural journalists incorporate a more inclusive and diverse set of norms into their conceptualisation of such practice. At the same time, the two groups nevertheless respond similarly when commenting on institutional factors at MBC that constrain or enable them to produce journalism about climate change that is guided by such norms. They place emphasis on the need for MBC to provide opportunities for journalists to have access to training, facilitated by organisations that have expertise in climate change journalism. It is concluded that the participants recognise that, despite the entrenched culture of authoritarianism at MBC, such workshops can contribute fundamentally to the shaping of journalistic practice within this broadcaster.
- Full Text:
- Authors: Kapiri, Francis
- Date: 2017
- Subjects: Public radio -- Malawi , Climatic changes in mass media , Climatic changes in mass media -- Case studies -- Malawi , Radio in agriculture -- Malawi , Malawi Broadcasting Corporation
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/6375 , vital:21100
- Description: This study investigates how radio journalists at the Malawian public broadcaster (MBC) experience the task of producing content that can help their audiences to engage with the local relevance of climate change. This study establishes terms of reference for this research by mapping out international histories of public engagement with the concept of climate change in the domains of science, politics and the media. It describes how contestations around climate change have evolved within these spheres and concludes that such contestation is shaped by relations of power that inform the international economic domain. The study then examines scholarly evaluations of journalism about climate change, concluding that such evaluation is grounded in distinct normative understandings of the social purpose of such journalism. It is argued that research about Malawian journalists’ experience of reporting on climate change should draw on knowledge of the role that norms play within this local environment. With this goal in mind, the study reviews tools for the analysis of the normative foundations of journalism within specific socio-historic contexts. It demonstrates the relevance of these tools for the identification of norms and their influence on journalism about climate change in the Malawian context. The empirical component of the study draws on this framework by means of a case study of the experiences of journalists working at the MBC. It examines how these journalists experience the task of producing content that enables their audiences to engage with the local relevance of climate change. It compares such experience as articulated by journalists working for agricultural and news programming. It is concluded that the participants have access to credible knowledge about climate change and its relevance to the Malawian context. Based on such knowledge, they articulate a shared understanding of climate change and its relevance to the Malawian context. However, the study identifies differences in the way that the two groups make sense of the practice of producing journalism about climate change that is of relevance to their audience. In particular, the agricultural journalists incorporate a more inclusive and diverse set of norms into their conceptualisation of such practice. At the same time, the two groups nevertheless respond similarly when commenting on institutional factors at MBC that constrain or enable them to produce journalism about climate change that is guided by such norms. They place emphasis on the need for MBC to provide opportunities for journalists to have access to training, facilitated by organisations that have expertise in climate change journalism. It is concluded that the participants recognise that, despite the entrenched culture of authoritarianism at MBC, such workshops can contribute fundamentally to the shaping of journalistic practice within this broadcaster.
- Full Text:
Progress in implementing the ecosystem approach to fisheries in South Africa in principle and in practice
- Duna, Elethu Zamandlane Lona
- Authors: Duna, Elethu Zamandlane Lona
- Date: 2017
- Subjects: Fisheries -- Environmental aspects -- South Africa , Sustainable fisheries -- South Africa , Fishery management -- South Africa , South African Sustainable Seafood Initiative
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/44879 , vital:25449
- Description: Over the last century, the population of the world has more than doubled, resulting in an increase in seafood consumption (FAO 2010), and placing strain on fisheries wild stocks, their habitats, and the coastal communities that rely on them for food and survival. The ecosystem approach to fisheries (EAF) differs from other management approaches by combining all aspects of ecosystem management, and strives to conserve ecosystem structure, maintain diversity, productivity, and integrity, and to meet human food and economic needs. This study aims to assess how South Africa is progressing in implementing EAF in principle and in practice, to identify challenges, and suggest solutions, where appropriate. The law sets precedence on governance. An assessment of the Marine Living Resources Act, (MLRA) and the South African Policy for Small-scale Fisheries (SSFP) revealed that, although these instruments recognise and contain elements of EAF, this management approach has not been adequately implemented. In practice, the status of implementation of EAF was assessed through the Southern African Sustainable Seafood Initiative (SASSI) and the Ecological Risk Assessments (ERA). The scores of 65 assessments, conducted in 2013 and 2014, were obtained from SASSI. Of the 65 species assessed; 18.4% were listed as Green, 50.8% were listed as Orange and 30.8% were listed as Red. Two methods were used to analyse the data; non-metric multidimensional scaling (NMDS), and cluster analysis in the statistical program R. Analysis of the SASSI assessments indicates that there has been progress in implementing EAF since the World Summit on Sustainable Development in 2002. The high number of Orange and Red listed species however, indicate that major sustainability issues still exist. Species in commercially important fisheries enjoy the bulk of research and management attention compared to other species, including bycatch species, as reflected by a high proportion of Green-rated commercially important species. Based on these results, four fisheries were chosen for further indepth analysis using additional information found in ecological risk assessments: offshore demersal trawl, inshore demersal trawl, West Coast rock lobster fishery and the line fishery. The documents and published literature of the Department of Agriculture, Forestry and Fisheries Internal Scientific Working Groups provided further information. A Wilcoxon signed rank test conducted in the programme R on the results of the ERAs showed that there was a decline in implementation of EAF and reinforced the earlier conclusion that large commercial fisheries, offshore and inshore demersal trawl, were progressing in implementing EAF faster than West Coast rock lobster and line fisheries, which are examples of smaller-scale fisheries that are more accessible to many resource users. Both progress and challenges appeared to be largely influenced by several common factors, which include the presence or absence of positive incentives, co-management, management plans, access, compliance, economic importance, capacity, and the interests of rights holders and other stakeholders.
- Full Text:
- Authors: Duna, Elethu Zamandlane Lona
- Date: 2017
- Subjects: Fisheries -- Environmental aspects -- South Africa , Sustainable fisheries -- South Africa , Fishery management -- South Africa , South African Sustainable Seafood Initiative
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/44879 , vital:25449
- Description: Over the last century, the population of the world has more than doubled, resulting in an increase in seafood consumption (FAO 2010), and placing strain on fisheries wild stocks, their habitats, and the coastal communities that rely on them for food and survival. The ecosystem approach to fisheries (EAF) differs from other management approaches by combining all aspects of ecosystem management, and strives to conserve ecosystem structure, maintain diversity, productivity, and integrity, and to meet human food and economic needs. This study aims to assess how South Africa is progressing in implementing EAF in principle and in practice, to identify challenges, and suggest solutions, where appropriate. The law sets precedence on governance. An assessment of the Marine Living Resources Act, (MLRA) and the South African Policy for Small-scale Fisheries (SSFP) revealed that, although these instruments recognise and contain elements of EAF, this management approach has not been adequately implemented. In practice, the status of implementation of EAF was assessed through the Southern African Sustainable Seafood Initiative (SASSI) and the Ecological Risk Assessments (ERA). The scores of 65 assessments, conducted in 2013 and 2014, were obtained from SASSI. Of the 65 species assessed; 18.4% were listed as Green, 50.8% were listed as Orange and 30.8% were listed as Red. Two methods were used to analyse the data; non-metric multidimensional scaling (NMDS), and cluster analysis in the statistical program R. Analysis of the SASSI assessments indicates that there has been progress in implementing EAF since the World Summit on Sustainable Development in 2002. The high number of Orange and Red listed species however, indicate that major sustainability issues still exist. Species in commercially important fisheries enjoy the bulk of research and management attention compared to other species, including bycatch species, as reflected by a high proportion of Green-rated commercially important species. Based on these results, four fisheries were chosen for further indepth analysis using additional information found in ecological risk assessments: offshore demersal trawl, inshore demersal trawl, West Coast rock lobster fishery and the line fishery. The documents and published literature of the Department of Agriculture, Forestry and Fisheries Internal Scientific Working Groups provided further information. A Wilcoxon signed rank test conducted in the programme R on the results of the ERAs showed that there was a decline in implementation of EAF and reinforced the earlier conclusion that large commercial fisheries, offshore and inshore demersal trawl, were progressing in implementing EAF faster than West Coast rock lobster and line fisheries, which are examples of smaller-scale fisheries that are more accessible to many resource users. Both progress and challenges appeared to be largely influenced by several common factors, which include the presence or absence of positive incentives, co-management, management plans, access, compliance, economic importance, capacity, and the interests of rights holders and other stakeholders.
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Quantifying degraded subtropical thicket structure and composition: a multi-scale approach in the Eastern Cape, South Africa
- Authors: Lunderstedt, Kyra Elizabeth
- Date: 2017
- Subjects: Portulacaceae -- South Africa -- Eastern Cape , Biodiversity conservation -- South Africa -- Eastern Cape , Savanna ecology -- South Africa -- Eastern Cape , Shrubs -- South Africa -- Eastern Cape , Succulent plants -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5281 , vital:20804
- Description: The loss in canopy cover from over-browsing severely degrades the ecological integrity of spekboom-dominated thicket in the Eastern Cape. A homogenisation of species across the landscape and high heterogeneity at fine scales has been reported with little evidence of recovery. As an interlinked consequence, the loss in important biological structures and composition impacts greatly on soil resources and therefore function. This thesis provides a baseline of degraded thicket abiotic and biotic structure and composition over both spatial and temporal scales within the Greater Addo Elephant National Park (GAENP), including Darlington, Kabouga and Addo Main and within the Baviaanskloof. The study aimed to find correlates of species composition within sites and assess changes in composition with degradation and recovery times. Across the GAENP, landscape degradation was most evident in post-1960 aerial imagery. The duration since sampled sites have been incorporated into the GAENP did not influence species composition, however the period of degradation and severity, did. Across the landscape, communities were strongly associated with each of the four sites and separated predominantly by rainfall, gravel and altitude. A total of 345 plant species were identified across the landscape and despite degradation, each site was characterised into three to five communities each, barring Baviaanskloof which had no significantly different communities. Across the landscape, matrix composition comprised predominantly of Pentzia incana, Drosanthemum hispidum, Galenia pubescens and Cynodon species. Woody cover within patches included smaller Grewia robusta, Rhigozum obovatum and Vachellia karroo and the larger Pappea capensis and Euclea undulata. The succulent shrub Euphorbia caerulescens in Darlington and succulent tree Aloe ferox in Baviaanskloof occurred abundantly as a consequence of degradation. Species richness was significantly correlated to patch size in all sites, but Kabouga had the greatest richness and probability of a suite of species occurring within a patch. Higher woody and succulent cover in Kabouga was therefore associated with higher soil C, root percentage and bulk density. Other sites were higher in Ca, Na, K and P. The method of degradation scoring was not sufficiently accurate and it is recommended that indicator species within the matrix should be used instead of growth forms. The findings of this thesis are conceptualised within a double-cusped catastrophe model and recommendations for restoration are provided.
- Full Text:
- Authors: Lunderstedt, Kyra Elizabeth
- Date: 2017
- Subjects: Portulacaceae -- South Africa -- Eastern Cape , Biodiversity conservation -- South Africa -- Eastern Cape , Savanna ecology -- South Africa -- Eastern Cape , Shrubs -- South Africa -- Eastern Cape , Succulent plants -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5281 , vital:20804
- Description: The loss in canopy cover from over-browsing severely degrades the ecological integrity of spekboom-dominated thicket in the Eastern Cape. A homogenisation of species across the landscape and high heterogeneity at fine scales has been reported with little evidence of recovery. As an interlinked consequence, the loss in important biological structures and composition impacts greatly on soil resources and therefore function. This thesis provides a baseline of degraded thicket abiotic and biotic structure and composition over both spatial and temporal scales within the Greater Addo Elephant National Park (GAENP), including Darlington, Kabouga and Addo Main and within the Baviaanskloof. The study aimed to find correlates of species composition within sites and assess changes in composition with degradation and recovery times. Across the GAENP, landscape degradation was most evident in post-1960 aerial imagery. The duration since sampled sites have been incorporated into the GAENP did not influence species composition, however the period of degradation and severity, did. Across the landscape, communities were strongly associated with each of the four sites and separated predominantly by rainfall, gravel and altitude. A total of 345 plant species were identified across the landscape and despite degradation, each site was characterised into three to five communities each, barring Baviaanskloof which had no significantly different communities. Across the landscape, matrix composition comprised predominantly of Pentzia incana, Drosanthemum hispidum, Galenia pubescens and Cynodon species. Woody cover within patches included smaller Grewia robusta, Rhigozum obovatum and Vachellia karroo and the larger Pappea capensis and Euclea undulata. The succulent shrub Euphorbia caerulescens in Darlington and succulent tree Aloe ferox in Baviaanskloof occurred abundantly as a consequence of degradation. Species richness was significantly correlated to patch size in all sites, but Kabouga had the greatest richness and probability of a suite of species occurring within a patch. Higher woody and succulent cover in Kabouga was therefore associated with higher soil C, root percentage and bulk density. Other sites were higher in Ca, Na, K and P. The method of degradation scoring was not sufficiently accurate and it is recommended that indicator species within the matrix should be used instead of growth forms. The findings of this thesis are conceptualised within a double-cusped catastrophe model and recommendations for restoration are provided.
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Queering boundaries: visual Activism and representations of sexuality in the work of contemporary South African artists
- Authors: Littleford, Lara
- Date: 2017
- Subjects: Homosexuality in art -- South Africa , Photographers, Black -- South Africa , Gay photographers -- South Africa , Lesbian photographers -- South Africa , Transgender people in art -- South Africa , Muholi, Zanele , Mlangeni, Sabelo
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: http://hdl.handle.net/10962/17816 , vital:22283
- Description: Zanele Muholi, a photographer and visual activist, and Sabelo Mlangeni, a photographer, explore the different ways of representing gender, particularly transgenderism, and sexuality, particularly homosexuality, in their photography. Muholi and Mlangeni document the daily lives and lived realities of people who are black and gay, lesbian, bisexual and transgender (LGBT) in South Africa. African sexuality remains a contested subject that is difficult to discuss in light of the controversies it provokes due to colonial attitudes toward African bodies. In this instance, colonial attitudes toward African sexuality have exoticised African bodies. Moreover, hyper-sexuality is ascribed to bodies that are black and male, whilst fetishising and objectifying black female bodies. Furthermore, representations of homoeroticism in Africa transgress and challenge dominant ideologies of sexuality and gender in an African context. In this sense, Muholi and Mlangeni directly address tension and resistance between individual and community. Such tensions are found within and between categories of African-ness, whereby homosexuality and transgenderism are regarded as being ‘un-African’ and an import from the West. For example, Muholi represents the existence of homosexuality and transgenderism in her photography in order to subvert the notion that homosexuality is ‘un-African’, attempting to complicate the conceptions of identity, gender and sexuality in South Africa. Muholi’s photography is used as a vehicle for her ‘visual activism’, which purports to create socio-political awareness surrounding homophobia, transgenderism, and epistemic injustice in South Africa. The visual imagery of these two artists investigates the boundaries that are set by various social, political and cultural constructs. These boundaries inform existing social, political and cultural attitudes toward homosexuality and transgenderism, and these homophobic and transphobic attitudes result in crimes committed against homosexual and transgender individuals, such as hate crimes, which includes ‘curative/corrective’ rape, the prevalence of which is rising at an alarming rate. Muholi’s photography and visual activism seek to create visibility in order to raise public awareness of hate crimes, victimisation, alienation and stigmatisation that homosexual and transgender South Africans, specifically those individuals living in township areas, face on a daily basis. These two artists represent sexuality as a site of contestation and, as such, heteronormative traditions, hegemonic social structures, and cultural conventions are transgressed and contested in their photography.
- Full Text:
- Authors: Littleford, Lara
- Date: 2017
- Subjects: Homosexuality in art -- South Africa , Photographers, Black -- South Africa , Gay photographers -- South Africa , Lesbian photographers -- South Africa , Transgender people in art -- South Africa , Muholi, Zanele , Mlangeni, Sabelo
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: http://hdl.handle.net/10962/17816 , vital:22283
- Description: Zanele Muholi, a photographer and visual activist, and Sabelo Mlangeni, a photographer, explore the different ways of representing gender, particularly transgenderism, and sexuality, particularly homosexuality, in their photography. Muholi and Mlangeni document the daily lives and lived realities of people who are black and gay, lesbian, bisexual and transgender (LGBT) in South Africa. African sexuality remains a contested subject that is difficult to discuss in light of the controversies it provokes due to colonial attitudes toward African bodies. In this instance, colonial attitudes toward African sexuality have exoticised African bodies. Moreover, hyper-sexuality is ascribed to bodies that are black and male, whilst fetishising and objectifying black female bodies. Furthermore, representations of homoeroticism in Africa transgress and challenge dominant ideologies of sexuality and gender in an African context. In this sense, Muholi and Mlangeni directly address tension and resistance between individual and community. Such tensions are found within and between categories of African-ness, whereby homosexuality and transgenderism are regarded as being ‘un-African’ and an import from the West. For example, Muholi represents the existence of homosexuality and transgenderism in her photography in order to subvert the notion that homosexuality is ‘un-African’, attempting to complicate the conceptions of identity, gender and sexuality in South Africa. Muholi’s photography is used as a vehicle for her ‘visual activism’, which purports to create socio-political awareness surrounding homophobia, transgenderism, and epistemic injustice in South Africa. The visual imagery of these two artists investigates the boundaries that are set by various social, political and cultural constructs. These boundaries inform existing social, political and cultural attitudes toward homosexuality and transgenderism, and these homophobic and transphobic attitudes result in crimes committed against homosexual and transgender individuals, such as hate crimes, which includes ‘curative/corrective’ rape, the prevalence of which is rising at an alarming rate. Muholi’s photography and visual activism seek to create visibility in order to raise public awareness of hate crimes, victimisation, alienation and stigmatisation that homosexual and transgender South Africans, specifically those individuals living in township areas, face on a daily basis. These two artists represent sexuality as a site of contestation and, as such, heteronormative traditions, hegemonic social structures, and cultural conventions are transgressed and contested in their photography.
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Real-time audio spectrum analyser research, design, development and implementation using the 32 bit ARMR Cortex-M4 microcontroller
- Authors: Just, Stefan Antonio
- Date: 2017
- Subjects: Spectrum analyzers , Sound -- Recording and reproducing -- Digital techniques , Real-time data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50536 , vital:25997
- Description: This thesis describes the design and testing of a low-cost hand-held real-time audio analyser (RTAA). This includes the design of an embedded system, the development of the firmware executed by the embedded system, and the implementation of a real-time signal processing algorithms. One of the objectives of this project was to design an alternative low-cost audio analyser to the current commercially available solutions. The device was tested with the audio standard test signal (pink noise) and was compared to the expected at-spectrum response corresponding to a balanced audio system. The design makes use of an 32-bit Reduced Instruction Set Computer (RISC) processor core (ARM Cortex-M4), namely the STM32F4 family of microcontrollers. Due to the pin compatibility of the microcontroller (designed and manufactured by STMicroelectronics), the new development board can also be upgraded with the newly released Cortex-M7 microcontroller, namely the STM32F7 family of microcontrollers. Moreover, the low-cost hardware design features 256kB Random Access Memory (RAM); on-board Micro-Electro-Mechanical System (MEMS) microphone; on-chip 12-bit Analogue-to-Digital (A/D) and Digital-to-Analogue (D/A) Converters; 3.2" Thin-Film-Transistor Liquid-Crystal Display (TFT-LCD) with a resistive touch screen sensor and SD-Card Socket. Furthermore, two additional expansion modules were designed and can extend the functionality of the designed real-time audio analyser. Firstly, an audio/video module featuring a professional 24-bit 192kHz sampling rate audio CODEC; balanced audio microphone input; unbalanced line output; three MEMS microphone inputs; headphone output; and a Video Graphics Array (VGA) controller allowing the display of the analysed audio spectrum on either a projector or monitor. The second expansion module features two external memories: 1MB Static Random Access Memory (SRAM) and 16MB Synchronous Dynamic Random Access Memory (SDRAM). While the two additional expansion modules were not completely utilised by the firmware presented in this thesis, upgrades of the real-time audio analyser firmware in future revisions will provide a higher performing and more accurate analysis of the audio spectrum. The full research and design process for the real-time audio analyser is discussed and both Problems and pitfalls with the final implemented design are highlighted and possible resolutions were investigated. The development costs (excluding labour) are given in the form of a bill of materials (BOM) with the total costs averaging around R1000. Moreover, the additional VGA controller could further decrease the overall costs with the removal of the TFT-LCD screen from the audio analyser and provided the external display was not included in the BOM.
- Full Text:
- Authors: Just, Stefan Antonio
- Date: 2017
- Subjects: Spectrum analyzers , Sound -- Recording and reproducing -- Digital techniques , Real-time data processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50536 , vital:25997
- Description: This thesis describes the design and testing of a low-cost hand-held real-time audio analyser (RTAA). This includes the design of an embedded system, the development of the firmware executed by the embedded system, and the implementation of a real-time signal processing algorithms. One of the objectives of this project was to design an alternative low-cost audio analyser to the current commercially available solutions. The device was tested with the audio standard test signal (pink noise) and was compared to the expected at-spectrum response corresponding to a balanced audio system. The design makes use of an 32-bit Reduced Instruction Set Computer (RISC) processor core (ARM Cortex-M4), namely the STM32F4 family of microcontrollers. Due to the pin compatibility of the microcontroller (designed and manufactured by STMicroelectronics), the new development board can also be upgraded with the newly released Cortex-M7 microcontroller, namely the STM32F7 family of microcontrollers. Moreover, the low-cost hardware design features 256kB Random Access Memory (RAM); on-board Micro-Electro-Mechanical System (MEMS) microphone; on-chip 12-bit Analogue-to-Digital (A/D) and Digital-to-Analogue (D/A) Converters; 3.2" Thin-Film-Transistor Liquid-Crystal Display (TFT-LCD) with a resistive touch screen sensor and SD-Card Socket. Furthermore, two additional expansion modules were designed and can extend the functionality of the designed real-time audio analyser. Firstly, an audio/video module featuring a professional 24-bit 192kHz sampling rate audio CODEC; balanced audio microphone input; unbalanced line output; three MEMS microphone inputs; headphone output; and a Video Graphics Array (VGA) controller allowing the display of the analysed audio spectrum on either a projector or monitor. The second expansion module features two external memories: 1MB Static Random Access Memory (SRAM) and 16MB Synchronous Dynamic Random Access Memory (SDRAM). While the two additional expansion modules were not completely utilised by the firmware presented in this thesis, upgrades of the real-time audio analyser firmware in future revisions will provide a higher performing and more accurate analysis of the audio spectrum. The full research and design process for the real-time audio analyser is discussed and both Problems and pitfalls with the final implemented design are highlighted and possible resolutions were investigated. The development costs (excluding labour) are given in the form of a bill of materials (BOM) with the total costs averaging around R1000. Moreover, the additional VGA controller could further decrease the overall costs with the removal of the TFT-LCD screen from the audio analyser and provided the external display was not included in the BOM.
- Full Text:
Red cotton
- Authors: Gantsho, Vangile
- Date: 2017
- Subjects: Creative writing (Higher education) South Africa , South African poetry (English) 21st century , South African poetry (English) Black authors , Lesbians, Black Poetry
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/7213 , vital:21229
- Description: My collection of poetry is a deeply personal exploration of what it means to be black, queer, and woman in modern-day South Africa. I interrogate being non-conformist in both a traditional-cultural upbringing and a more liberal yet equally-oppressive urban socialisation. I question what we are taught about the body and the feminine sexual space, while also addressing the mother-daughter relationship as the first and most constant reference of womanhood. The collection moves fluidly between the erotic, the uncomfortable and grotesque, what is painful, and what is beautiful and longed-for. Working promiscuously across forms, I employ prose poetry, interspersed with lyrical interludes, in an attempt at a narrative effect similar to what Claudia Rankine achieves in Don't Let Me Be Lonely. I also draw from writers such as Calixthe Beyala (Your Name Shall Be Tanga), and Janice Lee (Damnation), as well as sex guides, women's blogs, and feminist poetry.
- Full Text:
- Authors: Gantsho, Vangile
- Date: 2017
- Subjects: Creative writing (Higher education) South Africa , South African poetry (English) 21st century , South African poetry (English) Black authors , Lesbians, Black Poetry
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/7213 , vital:21229
- Description: My collection of poetry is a deeply personal exploration of what it means to be black, queer, and woman in modern-day South Africa. I interrogate being non-conformist in both a traditional-cultural upbringing and a more liberal yet equally-oppressive urban socialisation. I question what we are taught about the body and the feminine sexual space, while also addressing the mother-daughter relationship as the first and most constant reference of womanhood. The collection moves fluidly between the erotic, the uncomfortable and grotesque, what is painful, and what is beautiful and longed-for. Working promiscuously across forms, I employ prose poetry, interspersed with lyrical interludes, in an attempt at a narrative effect similar to what Claudia Rankine achieves in Don't Let Me Be Lonely. I also draw from writers such as Calixthe Beyala (Your Name Shall Be Tanga), and Janice Lee (Damnation), as well as sex guides, women's blogs, and feminist poetry.
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Regulation of cell biology by extracellular species of the Hsp90- Hsp70 organising protein (Hop)
- Authors: Höft, Maxine Allison
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59199 , vital:27465
- Description: Expected release date-April 2019
- Full Text:
- Authors: Höft, Maxine Allison
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59199 , vital:27465
- Description: Expected release date-April 2019
- Full Text:
Release success of captive bred Cape Vultures (Gyps coprotheres) in the Magaliesberg Mountains, South Africa
- Authors: Hirschauer, Maggie
- Date: 2017
- Subjects: Vultures -- South Africa -- Magaliesburg , Vultures -- South Africa -- Behavior
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4743 , vital:20720
- Description: The Cape Vulture, Gyps coprotheres, is currently classified as ‘endangered’. Endemic to southern Africa, its population has declined continuously over the past 40 years. The species is facing multiple anthropogenic threats. Notably, birds frequently collide with power lines and some cannot be released after treatment. This has led to the establishment of a captive breeding population with the hope that captive bred young can supplement wild populations and re-establish a now- abandoned breeding colony in the Magaliesberg Mountains, South Africa. This study aimed to follow the breeding behaviours of the captive colony and assess the appropriateness of chick rearing conditions. The study also aimed to monitor the behaviour, physical condition and dispersal of ten captive bred vultures after release in relation to their age. Behavioural observations of captive adult breeding and parental behaviours were conducted to establish whether chicks developed under comparable conditions to wild chicks. A high percentage of total colony copulation attempts (22 %) were extra-pair copulations. Four paired males formed ephemeral extra-pair relationships, two of which were homosexual. Chicks fledged earlier than wild chicks, on average at 128 days old. Wild and captive bred birds were observed at carcasses to compare competitive and feeding behaviours. Older birds, both wild and captive, fed the most efficiently. Preliminary evidence suggests females are more dominant and have higher display rates than males. Captive bred juvenile and four year old birds’ competitive and feeding behaviours (interaction rate, feeding rate, display rate, dominance, aggressiveness, and feeding efficiency) were the closest to, but still generally below, average values for same-aged wild birds. An index of body condition, body mass, and the prevalence of fault bars on the rectrices were used to assess their physical condition. After eight months, none of the ten birds had moved more than 8 km from the release site, nor had they foraged away from the vulture restaurant on site. Although altitude records of > 3100 m were recorded, their flight skills seemed inadequate. Future management considerations include the initiation of a pre-release exercise regime, the establishment of an acclimatization enclosure removed from the breeding site, and a varied or reduced post-release feeding schedule. Fledglings should be relocated and housed at the release enclosure until they are four years old.
- Full Text:
- Authors: Hirschauer, Maggie
- Date: 2017
- Subjects: Vultures -- South Africa -- Magaliesburg , Vultures -- South Africa -- Behavior
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4743 , vital:20720
- Description: The Cape Vulture, Gyps coprotheres, is currently classified as ‘endangered’. Endemic to southern Africa, its population has declined continuously over the past 40 years. The species is facing multiple anthropogenic threats. Notably, birds frequently collide with power lines and some cannot be released after treatment. This has led to the establishment of a captive breeding population with the hope that captive bred young can supplement wild populations and re-establish a now- abandoned breeding colony in the Magaliesberg Mountains, South Africa. This study aimed to follow the breeding behaviours of the captive colony and assess the appropriateness of chick rearing conditions. The study also aimed to monitor the behaviour, physical condition and dispersal of ten captive bred vultures after release in relation to their age. Behavioural observations of captive adult breeding and parental behaviours were conducted to establish whether chicks developed under comparable conditions to wild chicks. A high percentage of total colony copulation attempts (22 %) were extra-pair copulations. Four paired males formed ephemeral extra-pair relationships, two of which were homosexual. Chicks fledged earlier than wild chicks, on average at 128 days old. Wild and captive bred birds were observed at carcasses to compare competitive and feeding behaviours. Older birds, both wild and captive, fed the most efficiently. Preliminary evidence suggests females are more dominant and have higher display rates than males. Captive bred juvenile and four year old birds’ competitive and feeding behaviours (interaction rate, feeding rate, display rate, dominance, aggressiveness, and feeding efficiency) were the closest to, but still generally below, average values for same-aged wild birds. An index of body condition, body mass, and the prevalence of fault bars on the rectrices were used to assess their physical condition. After eight months, none of the ten birds had moved more than 8 km from the release site, nor had they foraged away from the vulture restaurant on site. Although altitude records of > 3100 m were recorded, their flight skills seemed inadequate. Future management considerations include the initiation of a pre-release exercise regime, the establishment of an acclimatization enclosure removed from the breeding site, and a varied or reduced post-release feeding schedule. Fledglings should be relocated and housed at the release enclosure until they are four years old.
- Full Text: