The perceived economic impact of the city of Johannesburg's storm water attenuation policy on private property developers
- Authors: Aldous, Michael Geoffrey
- Date: 2007
- Subjects: Runoff -- South Africa -- Johannesburg , Real estate development -- South Africa -- Johannesburg
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9668 , http://hdl.handle.net/10948/765 , Runoff -- South Africa -- Johannesburg , Real estate development -- South Africa -- Johannesburg
- Description: Stormwater attenuation policy has, over recent years, become a highly contentious issue for the property development community. Increased urbanisation, locally and internationally, has forced municipal authorities to reconsider the role of stormwater management in this evolving urban landscape. It is within this context that the legislative support and municipal policy for stormwater management in the City of Johannesburg has been explored, particularly in terms of the economic impact on property developers. The research aimed to explore the relationship between stormwater attenuation policy and the economic impact thereof on private property developers. Consideration was given to the cost, risk and time factors of legislative and policy requirements within the development process. Further consideration was given to the physical environment that has brought about current pressures. Based upon research of international issues highlighted in countries with well developed attenuation policy, a questionnaire was constructed to evaluate the response of local private property developers to selected issues as key sub-problems. The responses were tested against the developed set of hypotheses. The research indicated that developers had a generally poor level of knowledge with regard to the stormwater management policy of the City of Johannesburg, as well as the supporting legislative requirements of provincial and national policy documents. The results of the survey also indicated that developers were strongly opposed to the loss of developable area, but indicated a limited financial impact of the current stormwater attenuation policy. The risk inherent in incorporating an attenuation facility within a development was identified as being low with little perceived impact. Developers further indicated that the inclusion of attenuation facilities was seen as a significant contributing factor in the delay, approval and acceptance of new developments in which attenuation facilities were required, while maintenance costs were indicated to be of a low level of importance. Recommendations in response to the research findings included the establishment of detailed policy documentation and support for effective distribution channels in conjunction with industry and public focused information campaigns, improved municipal capacity and a greater level of technical support. A need for additional stormwater research and an increase in the capture of relevant data for GIS purposes was identified.
- Full Text:
- Date Issued: 2007
- Authors: Aldous, Michael Geoffrey
- Date: 2007
- Subjects: Runoff -- South Africa -- Johannesburg , Real estate development -- South Africa -- Johannesburg
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9668 , http://hdl.handle.net/10948/765 , Runoff -- South Africa -- Johannesburg , Real estate development -- South Africa -- Johannesburg
- Description: Stormwater attenuation policy has, over recent years, become a highly contentious issue for the property development community. Increased urbanisation, locally and internationally, has forced municipal authorities to reconsider the role of stormwater management in this evolving urban landscape. It is within this context that the legislative support and municipal policy for stormwater management in the City of Johannesburg has been explored, particularly in terms of the economic impact on property developers. The research aimed to explore the relationship between stormwater attenuation policy and the economic impact thereof on private property developers. Consideration was given to the cost, risk and time factors of legislative and policy requirements within the development process. Further consideration was given to the physical environment that has brought about current pressures. Based upon research of international issues highlighted in countries with well developed attenuation policy, a questionnaire was constructed to evaluate the response of local private property developers to selected issues as key sub-problems. The responses were tested against the developed set of hypotheses. The research indicated that developers had a generally poor level of knowledge with regard to the stormwater management policy of the City of Johannesburg, as well as the supporting legislative requirements of provincial and national policy documents. The results of the survey also indicated that developers were strongly opposed to the loss of developable area, but indicated a limited financial impact of the current stormwater attenuation policy. The risk inherent in incorporating an attenuation facility within a development was identified as being low with little perceived impact. Developers further indicated that the inclusion of attenuation facilities was seen as a significant contributing factor in the delay, approval and acceptance of new developments in which attenuation facilities were required, while maintenance costs were indicated to be of a low level of importance. Recommendations in response to the research findings included the establishment of detailed policy documentation and support for effective distribution channels in conjunction with industry and public focused information campaigns, improved municipal capacity and a greater level of technical support. A need for additional stormwater research and an increase in the capture of relevant data for GIS purposes was identified.
- Full Text:
- Date Issued: 2007
An investigation of integrated development planning (IDP) as a mechanism for poverty alleviation in Grahamstown in the Makana Municipality, Eastern Cape, South Africa
- Authors: Alebiosu, Olumide Ademola
- Date: 2006
- Subjects: Makana Municipality , Local government -- South Africa -- Eastern Cape , Poor -- South Africa -- Eastern Cape , Poverty -- South Africa -- Eastern Cape , Poverty -- Government policy -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4841 , http://hdl.handle.net/10962/d1005517 , Makana Municipality , Local government -- South Africa -- Eastern Cape , Poor -- South Africa -- Eastern Cape , Poverty -- South Africa -- Eastern Cape , Poverty -- Government policy -- South Africa -- Eastern Cape
- Description: Poverty among individuals, households or communities is not a static condition. There are many factors which contribute to its causes and depth. In South Africa the economic gaps imposed by the previous apartheid government aggravated economic inequalities and caused considerable disparities, which has resulted in high unemployment rates. Inequalities were also manifest in the neglect of infrastructural and service provision as well in the effective absence of independent governance among some race group. This led to a call for pro-active initiatives by the post-1994 democratic government to remedy the living condition of the previously disadvantaged people. As part of its poverty relief drive the South African government has embarked on a series of developmental initiatives in bringing infrastructure related services to the poor and to reduce the enormous prevailing backlog, with the aim of increasing community participation, improving service delivery and promoting the upliftment of the lives of poor people through the medium of local governance. This study investigated the Integrated Development Planning, which has been undertaken in Grahamstown in the Makana Municipality in the Eastern Cape to respond to the prevailing poverty and underdevelopment among the poor communities. Relying on their developmental mandate to initiate and co-ordinate all development activities within their area of jurisdiction through the IDP, the Makana Municipality has drawn up a development strategic plan in conjunction with the local communities and with other stakeholders and organisations to identify and assess development backlogs within the communities with the aim of addressing such backlogs. This study revealed from the interviews conducted with some municipal personnel and questionnaires administered to sampled residents of Grahamstown that some faces of poverty, such as unemployment and lack of access to some of the most basic of infrastructure such as, sanitation facilities, water, electricity, formal house, education, security and recreation facilities are apparent in Grahamstown. However, the Makana Municipality through, the IDP has achieved some notable feats in the provision of providing some of the basic amenities such as water, housing, electricity and sanitation albeit at a slow rate. The mechanism of delivery is hampered by bureaucratic settings within government and the ambiguity attached to some of the projects. The service and infrastructural developments targeted towards the poor and the involvement of communities in the affairs of the local government might be seen as a partially panacea for poverty alleviation in South Africa. However the capacity of the local governments to effectively carry out this developmental challenge assignment might be a new twist in the developmental challenge facing local governments in South Africa. The thesis provides an overview of the Makana Municipality IDP and the degree to which is serving as one mechanism to address poverty in the Grahamstown urban area
- Full Text:
- Date Issued: 2006
- Authors: Alebiosu, Olumide Ademola
- Date: 2006
- Subjects: Makana Municipality , Local government -- South Africa -- Eastern Cape , Poor -- South Africa -- Eastern Cape , Poverty -- South Africa -- Eastern Cape , Poverty -- Government policy -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4841 , http://hdl.handle.net/10962/d1005517 , Makana Municipality , Local government -- South Africa -- Eastern Cape , Poor -- South Africa -- Eastern Cape , Poverty -- South Africa -- Eastern Cape , Poverty -- Government policy -- South Africa -- Eastern Cape
- Description: Poverty among individuals, households or communities is not a static condition. There are many factors which contribute to its causes and depth. In South Africa the economic gaps imposed by the previous apartheid government aggravated economic inequalities and caused considerable disparities, which has resulted in high unemployment rates. Inequalities were also manifest in the neglect of infrastructural and service provision as well in the effective absence of independent governance among some race group. This led to a call for pro-active initiatives by the post-1994 democratic government to remedy the living condition of the previously disadvantaged people. As part of its poverty relief drive the South African government has embarked on a series of developmental initiatives in bringing infrastructure related services to the poor and to reduce the enormous prevailing backlog, with the aim of increasing community participation, improving service delivery and promoting the upliftment of the lives of poor people through the medium of local governance. This study investigated the Integrated Development Planning, which has been undertaken in Grahamstown in the Makana Municipality in the Eastern Cape to respond to the prevailing poverty and underdevelopment among the poor communities. Relying on their developmental mandate to initiate and co-ordinate all development activities within their area of jurisdiction through the IDP, the Makana Municipality has drawn up a development strategic plan in conjunction with the local communities and with other stakeholders and organisations to identify and assess development backlogs within the communities with the aim of addressing such backlogs. This study revealed from the interviews conducted with some municipal personnel and questionnaires administered to sampled residents of Grahamstown that some faces of poverty, such as unemployment and lack of access to some of the most basic of infrastructure such as, sanitation facilities, water, electricity, formal house, education, security and recreation facilities are apparent in Grahamstown. However, the Makana Municipality through, the IDP has achieved some notable feats in the provision of providing some of the basic amenities such as water, housing, electricity and sanitation albeit at a slow rate. The mechanism of delivery is hampered by bureaucratic settings within government and the ambiguity attached to some of the projects. The service and infrastructural developments targeted towards the poor and the involvement of communities in the affairs of the local government might be seen as a partially panacea for poverty alleviation in South Africa. However the capacity of the local governments to effectively carry out this developmental challenge assignment might be a new twist in the developmental challenge facing local governments in South Africa. The thesis provides an overview of the Makana Municipality IDP and the degree to which is serving as one mechanism to address poverty in the Grahamstown urban area
- Full Text:
- Date Issued: 2006
The study of the metabolism of phenylbutazone (4-butyl-1,2 -diphenylpyrazolidine - 3,5 - dione) in rats
- Authors: Alexander, Dorothy Mary
- Date: 1978 , 2013-10-18
- Subjects: Drugs -- Metabolism , Phenylbutazone
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3832 , http://hdl.handle.net/10962/d1007468 , Drugs -- Metabolism , Phenylbutazone
- Description: In this study the metabolism of the anti-arthritic drug, phenylbutazone, was investigated in female Wistar rats, and the results compared with those of other workers in this field. Two interrelated projects were undertaken. The first covered the pattern of excretion, isolation and characterisation of the metabolites and decomposition products of phenylbutazone in rats dosed post-orally with the drug. It was found that the major route of excretion was via the urine and over 50% of the administered dose was excreted in the first 24 hours by this route. A small percentage of the dose was excreted in the faeces. The following compounds were identified using chromatographic and autoradiographic techniques: p-Hydroxy derivative of phenylbutazone γ-Hydroxy derivative of phenylbutazone in both its molecular forms (ring lactone and straight chain hydroxyl) 4-Hydroxy derivative of phenylbutazone p-γ-Dihydroxy derivative of phenylbutazone p-4-Dihydroxy derivative of phenylbutazone Hydrolysable conjugates (possibly glucuronides) Water soluble non-hydrolysable conjugates. The second project dealt with the quantitation of the water insoluble compounds isolated in the initial work. Using a unique technique, combining inverse isotope dilution assay and spectrophotometric analysis, it was found that the major metabolite was the γ-hydroxy derivative of phenylbutazone, present in both its molecular forms. Oxyphenbutazone was a minor metabolite and the p-γ-dihydroxy derivative of phenylbutazone was present only in very low concentration. These results did not conform with those of previous workers in this field who reported the γ-hydroxy derivative of phenylbutazone, in one molecular form only, as the major metabolite and the dihydroxy derivative as the second metabolite with a higher concentration in the urine than oxyphenbutazone. This disparity could be due to the fact that these workers took no account of the presence of the two molecular forms of the γ-hydroxy derivative of phenylbutazone with their different polarities and different Rf values. The present study showed that the straight chain hydroxyl isomer was probably mistakenly identified as the p-γ-dihydroxy derivative of phenylbutazone. This theory is supported by the fact that the percentage dose recovered by the previous workers of the γ-hydroxy and p-γ-dihydroxy derivatives together equalled the percentage dose recovered in this study of the two molecular forms of the γ-hydroxy derivative. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
- Authors: Alexander, Dorothy Mary
- Date: 1978 , 2013-10-18
- Subjects: Drugs -- Metabolism , Phenylbutazone
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3832 , http://hdl.handle.net/10962/d1007468 , Drugs -- Metabolism , Phenylbutazone
- Description: In this study the metabolism of the anti-arthritic drug, phenylbutazone, was investigated in female Wistar rats, and the results compared with those of other workers in this field. Two interrelated projects were undertaken. The first covered the pattern of excretion, isolation and characterisation of the metabolites and decomposition products of phenylbutazone in rats dosed post-orally with the drug. It was found that the major route of excretion was via the urine and over 50% of the administered dose was excreted in the first 24 hours by this route. A small percentage of the dose was excreted in the faeces. The following compounds were identified using chromatographic and autoradiographic techniques: p-Hydroxy derivative of phenylbutazone γ-Hydroxy derivative of phenylbutazone in both its molecular forms (ring lactone and straight chain hydroxyl) 4-Hydroxy derivative of phenylbutazone p-γ-Dihydroxy derivative of phenylbutazone p-4-Dihydroxy derivative of phenylbutazone Hydrolysable conjugates (possibly glucuronides) Water soluble non-hydrolysable conjugates. The second project dealt with the quantitation of the water insoluble compounds isolated in the initial work. Using a unique technique, combining inverse isotope dilution assay and spectrophotometric analysis, it was found that the major metabolite was the γ-hydroxy derivative of phenylbutazone, present in both its molecular forms. Oxyphenbutazone was a minor metabolite and the p-γ-dihydroxy derivative of phenylbutazone was present only in very low concentration. These results did not conform with those of previous workers in this field who reported the γ-hydroxy derivative of phenylbutazone, in one molecular form only, as the major metabolite and the dihydroxy derivative as the second metabolite with a higher concentration in the urine than oxyphenbutazone. This disparity could be due to the fact that these workers took no account of the presence of the two molecular forms of the γ-hydroxy derivative of phenylbutazone with their different polarities and different Rf values. The present study showed that the straight chain hydroxyl isomer was probably mistakenly identified as the p-γ-dihydroxy derivative of phenylbutazone. This theory is supported by the fact that the percentage dose recovered by the previous workers of the γ-hydroxy and p-γ-dihydroxy derivatives together equalled the percentage dose recovered in this study of the two molecular forms of the γ-hydroxy derivative. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1978
The origin of endorheic pans on the African erosion surface North of Grahamstown, South Africa
- Authors: Alistoun, Judith Robyn
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4775 , http://hdl.handle.net/10962/d1011048
- Description: Pans on the African Erosion Surface near Grahamstown are small features, which, perhaps due to their small size have been neglected by researchers. From the outset the striking difference of these pans relative to other pans in southern Africa, is that the host rock is silcrete, a highly resistant rock well known as being associated with deeply weathered plateaus. The dominant origin theory for pans in southern Africa was developed by Goudie and Thomas (1985), and focuses on mechanisms relating to erosion and deflation. This model does not fit in well with the pans that have formed on substrate that has largely been unaffected by erosion in recent geological history (thousands to 10 000 years). As such this study examined the role of prolonged chemical weathering of Dwyka Tillite, that has led to the formation of silcrete. The hypothesis was that such deep weathering is responsible for local scale volume changes, which have in turn led to the formation of a depression. The centre of the pan indicated the highest concentration of Al₂O₃ and kaolinite at mid depths, and their concentrations decreased vertically away from these depths, and laterally towards the margins of the pan. Similar results were noted for SiO₂, while CaO and MgO (and calcite and dolomite) were highest at mid depths along the margins of the pan, and decreased laterally toward the centre of the pan. Results indicated that there was a positive relationship in the centre of the pan between: - the degree of chemical weathering and volume losses, - relative elevation of the pan and volume changes. Geochemically and mineralogically, there was a link between the high concentrations of Ca and Mg carbonates and volume gains in the margin of the pans. It is proposed that transpiration of vegetation along the margin of the pan caused the lateral movement of solutes, and the selective exclusion of these solutes by plants was associated with carbonate precipitation, leading to the creation of local relief. These results provide evidence to suggest that weathering and precipitation processes occurring over geological time scales are responsible for minor scale relief features, whose origin has been mistakenly attributed to deflation processes occurring over hundreds to thousands of years.
- Full Text:
- Date Issued: 2014
- Authors: Alistoun, Judith Robyn
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4775 , http://hdl.handle.net/10962/d1011048
- Description: Pans on the African Erosion Surface near Grahamstown are small features, which, perhaps due to their small size have been neglected by researchers. From the outset the striking difference of these pans relative to other pans in southern Africa, is that the host rock is silcrete, a highly resistant rock well known as being associated with deeply weathered plateaus. The dominant origin theory for pans in southern Africa was developed by Goudie and Thomas (1985), and focuses on mechanisms relating to erosion and deflation. This model does not fit in well with the pans that have formed on substrate that has largely been unaffected by erosion in recent geological history (thousands to 10 000 years). As such this study examined the role of prolonged chemical weathering of Dwyka Tillite, that has led to the formation of silcrete. The hypothesis was that such deep weathering is responsible for local scale volume changes, which have in turn led to the formation of a depression. The centre of the pan indicated the highest concentration of Al₂O₃ and kaolinite at mid depths, and their concentrations decreased vertically away from these depths, and laterally towards the margins of the pan. Similar results were noted for SiO₂, while CaO and MgO (and calcite and dolomite) were highest at mid depths along the margins of the pan, and decreased laterally toward the centre of the pan. Results indicated that there was a positive relationship in the centre of the pan between: - the degree of chemical weathering and volume losses, - relative elevation of the pan and volume changes. Geochemically and mineralogically, there was a link between the high concentrations of Ca and Mg carbonates and volume gains in the margin of the pans. It is proposed that transpiration of vegetation along the margin of the pan caused the lateral movement of solutes, and the selective exclusion of these solutes by plants was associated with carbonate precipitation, leading to the creation of local relief. These results provide evidence to suggest that weathering and precipitation processes occurring over geological time scales are responsible for minor scale relief features, whose origin has been mistakenly attributed to deflation processes occurring over hundreds to thousands of years.
- Full Text:
- Date Issued: 2014
Investigation of the performance of photovoltaic systems
- Authors: Alistoun, Warren James
- Date: 2012
- Subjects: Photovoltaic power systems -- South Africa , Photovoltaic power generation -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10517 , http://hdl.handle.net/10948/d1008396 , Photovoltaic power systems -- South Africa , Photovoltaic power generation -- South Africa
- Description: The main objective of this study was to investigate the performance of grid integrated PV systems. A data acquisition (DAQ) system was developed to monitor the performance of an existing grid integrated PV system with battery storage. This system is referred to as a grid assisted PV system. A data logger was used together with the inverters built in data logger to monitor environmental and electrical data on a grid tie PV system which was deployed during this study. To investigate the performance of these grid integrated PV systems PV and BOS device characterization was performed. This was achieved by using current voltage curve tracers and the DAQ system developed. Energy yield estimations were calculated referring to the literature review and a meteorological reference for comparison with measured energy yields from the grid tie PV system.
- Full Text:
- Date Issued: 2012
- Authors: Alistoun, Warren James
- Date: 2012
- Subjects: Photovoltaic power systems -- South Africa , Photovoltaic power generation -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10517 , http://hdl.handle.net/10948/d1008396 , Photovoltaic power systems -- South Africa , Photovoltaic power generation -- South Africa
- Description: The main objective of this study was to investigate the performance of grid integrated PV systems. A data acquisition (DAQ) system was developed to monitor the performance of an existing grid integrated PV system with battery storage. This system is referred to as a grid assisted PV system. A data logger was used together with the inverters built in data logger to monitor environmental and electrical data on a grid tie PV system which was deployed during this study. To investigate the performance of these grid integrated PV systems PV and BOS device characterization was performed. This was achieved by using current voltage curve tracers and the DAQ system developed. Energy yield estimations were calculated referring to the literature review and a meteorological reference for comparison with measured energy yields from the grid tie PV system.
- Full Text:
- Date Issued: 2012
Ecological role of free-living bacteria in the microbial food web of the temporarily open/closed East Kleinemonde Estuary, South Africa
- Authors: Allan, Elizabeth Louise
- Date: 2008
- Subjects: Bacterial growth -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape , Estuaries -- South Africa -- Eastern Cape , Microbial ecology -- South Africa -- Eastern Cape , Nutrient cycles -- South Africa -- Eastern Cape , Food chains (Ecology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5666 , http://hdl.handle.net/10962/d1005351 , Bacterial growth -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape , Estuaries -- South Africa -- Eastern Cape , Microbial ecology -- South Africa -- Eastern Cape , Nutrient cycles -- South Africa -- Eastern Cape , Food chains (Ecology)
- Description: The main aim of this study was to assess the “top-down” and “bottom-up” control of bacterial production in the small temporarily open/closed East Kleinemonde Estuary, situated on the south-eastern coastline of southern Africa. Spatial and temporal patterns in bacterial abundance, biomass and production and the importance of abiotic and biotic factors were investigated over the period May 2006 to April 2007. The trophic interactions between bacteria, phytoplankton, nanoflagellates (< 20 μm), microzooplankton (< 200 μm) and mesozooplankton (< 2 000 μm) were investigated during winter and summer. Bacterial abundance, biomass and production ranged between 1.00 × 10⁹ and 4.93 × 10⁹ cells 1⁻¹, 32.4 and 109 μg C 1⁻¹ and 0.01 and 1.99 μg C 1⁻¹ h⁻¹, respectively. With a few exceptions there were no spatial patterns in the values. Bacterial abundance, biomass and production, however, demonstrated a distinct temporal pattern with the lowest values consistently recorded during the winter months. Nanoflagellate and bacterial abundances were significantly correlated to one another (lower reaches: r = 0.818, p < 0.001; middle reaches: r = 0.628, p < 0.001; upper reaches: r = 0.484, p < 0.05) suggesting a strong predator-prey relationship. The frequency of visibly infected bacterial cells and the mean number of virus particles within each bacterial cell during this study demonstrated no temporal or spatial patterns and ranged from 0.5 to 6.1 % and 12.0 to 37.5 virus particles per bacterium, respectively. Viral infection and lysis was thus a constant source of bacterial mortality throughout the year. The estimated percentage of bacterial production removed by viral lysis ranged between 7.8 and 88.9% of the total which suggests that viral lysis represented a very important source of bacterial mortality during this study. The biological interactions between the selected components of the plankton community demonstrated that among the heterotrophic components of the plankton, the nanoflagellates were identified as the most important consumers of bacteria and small phytoplankton cells (< 20 μm). In the presence of microzooplankton the impact of the nanoflagellates on both the bacteria and phytoplankton was reduced, indicating that larger heterotrophs were preying upon the nanoflagellates. Mesozooplankton, however, appeared to exert the greatest impact on nanoflagellates. In the cascading experiments, the data suggest that mesozooplankton consume nanoflagellates, which resulted in a decrease in the predation impact of these organisms on the bacteria. This result is consistent with predator-prey cascades. The presence of the larger heterotrophs therefore, mediates the interactions between the primary bacterivores, the nanoflagellates, and the bacteria within the temporarily open/closed East Kleinemonde Estuary.
- Full Text:
- Date Issued: 2008
- Authors: Allan, Elizabeth Louise
- Date: 2008
- Subjects: Bacterial growth -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape , Estuaries -- South Africa -- Eastern Cape , Microbial ecology -- South Africa -- Eastern Cape , Nutrient cycles -- South Africa -- Eastern Cape , Food chains (Ecology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5666 , http://hdl.handle.net/10962/d1005351 , Bacterial growth -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape , Estuaries -- South Africa -- Eastern Cape , Microbial ecology -- South Africa -- Eastern Cape , Nutrient cycles -- South Africa -- Eastern Cape , Food chains (Ecology)
- Description: The main aim of this study was to assess the “top-down” and “bottom-up” control of bacterial production in the small temporarily open/closed East Kleinemonde Estuary, situated on the south-eastern coastline of southern Africa. Spatial and temporal patterns in bacterial abundance, biomass and production and the importance of abiotic and biotic factors were investigated over the period May 2006 to April 2007. The trophic interactions between bacteria, phytoplankton, nanoflagellates (< 20 μm), microzooplankton (< 200 μm) and mesozooplankton (< 2 000 μm) were investigated during winter and summer. Bacterial abundance, biomass and production ranged between 1.00 × 10⁹ and 4.93 × 10⁹ cells 1⁻¹, 32.4 and 109 μg C 1⁻¹ and 0.01 and 1.99 μg C 1⁻¹ h⁻¹, respectively. With a few exceptions there were no spatial patterns in the values. Bacterial abundance, biomass and production, however, demonstrated a distinct temporal pattern with the lowest values consistently recorded during the winter months. Nanoflagellate and bacterial abundances were significantly correlated to one another (lower reaches: r = 0.818, p < 0.001; middle reaches: r = 0.628, p < 0.001; upper reaches: r = 0.484, p < 0.05) suggesting a strong predator-prey relationship. The frequency of visibly infected bacterial cells and the mean number of virus particles within each bacterial cell during this study demonstrated no temporal or spatial patterns and ranged from 0.5 to 6.1 % and 12.0 to 37.5 virus particles per bacterium, respectively. Viral infection and lysis was thus a constant source of bacterial mortality throughout the year. The estimated percentage of bacterial production removed by viral lysis ranged between 7.8 and 88.9% of the total which suggests that viral lysis represented a very important source of bacterial mortality during this study. The biological interactions between the selected components of the plankton community demonstrated that among the heterotrophic components of the plankton, the nanoflagellates were identified as the most important consumers of bacteria and small phytoplankton cells (< 20 μm). In the presence of microzooplankton the impact of the nanoflagellates on both the bacteria and phytoplankton was reduced, indicating that larger heterotrophs were preying upon the nanoflagellates. Mesozooplankton, however, appeared to exert the greatest impact on nanoflagellates. In the cascading experiments, the data suggest that mesozooplankton consume nanoflagellates, which resulted in a decrease in the predation impact of these organisms on the bacteria. This result is consistent with predator-prey cascades. The presence of the larger heterotrophs therefore, mediates the interactions between the primary bacterivores, the nanoflagellates, and the bacteria within the temporarily open/closed East Kleinemonde Estuary.
- Full Text:
- Date Issued: 2008
Bacterial degradation of ixodicide amitraz
- Authors: Allcock, Errol Ralph
- Date: 1978
- Subjects: Ticks -- Control , Pesticides -- Biodegradation , Acaricides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4081 , http://hdl.handle.net/10962/d1007473 , Ticks -- Control , Pesticides -- Biodegradation , Acaricides
- Description: The control of ticks on cattle has long been a matter of prime importance to stock owners over most of the intensive natural grazing areas in the Southern Hemisphere. The only practical method of dealing with the cattle tick problem in the short term is by treating the infected bovine host with ixodicides i. e. by chemical control. This can be achieved by either plunging the cattle into a dip tank containing aqueous suspensions or emulsions of the ixodicide or by spraying them with dip suspensions in a spray race.
- Full Text:
- Date Issued: 1978
- Authors: Allcock, Errol Ralph
- Date: 1978
- Subjects: Ticks -- Control , Pesticides -- Biodegradation , Acaricides
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4081 , http://hdl.handle.net/10962/d1007473 , Ticks -- Control , Pesticides -- Biodegradation , Acaricides
- Description: The control of ticks on cattle has long been a matter of prime importance to stock owners over most of the intensive natural grazing areas in the Southern Hemisphere. The only practical method of dealing with the cattle tick problem in the short term is by treating the infected bovine host with ixodicides i. e. by chemical control. This can be achieved by either plunging the cattle into a dip tank containing aqueous suspensions or emulsions of the ixodicide or by spraying them with dip suspensions in a spray race.
- Full Text:
- Date Issued: 1978
Improving construction planning through 4D planning
- Authors: Allen, Christopher James
- Date: 2007
- Subjects: Construction industry -- Management , Construction industry -- Computer-aided design
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9698 , http://hdl.handle.net/10948/467 , http://hdl.handle.net/10948/d1011923 , Construction industry -- Management , Construction industry -- Computer-aided design
- Description: Construction Planning will increasingly play a more critical role within the realm of the Built Environment. Existing practices used to plan and communicate the construction process to be undertaken are failing to deliver the desired results for construction companies and clients alike. At a time of unprecedented growth in the industry around the world, which is leading to a general skills shortage, especially in management positions, construction planners are increasingly being asked to deal with more responsibility. As with other industries, technological improvement in the tools at their disposal is one way to address the inadequacies of the present situation. Increasingly, three dimensional design packages are being used to generate construction information which can then be used for quantities calculations, automated manufacturing processes and construction simulation. The latter forms the basis for their use in the process of planning, through new technologies being developed as virtual construction tools or 4D planning, the addition of time to the 3D model environment, but using the elements within the model as the basis for the construction programme. The benefit of using the design information to form the basis of the programme is that the interface tasks and logistical activities, as well as location related constraints, can be identified and then communicated to all levels within the construction team through a time based visual image. The purpose of this study is therefore to establish a scientifically analysed alternative method for the creation, review and delivery of construction programmes. In order to achieve the research objectives, three methodologies have been employed. Firstly, the literature review in the fields of planning including existing methodologies and previous research of 4D related techniques has been analysed. An overview of the perceived weaknesses to current practises and proposed solution will be explored and best case scenarios outlined and further investigated. Secondly, the 51 Lime Street project provides an environment in which the proposed 4D planning techniques have been implemented and the benefits of the process can, through observation / participation methodology, be validated. Thirdly, through interview questionnaires, with Lime St contractors and management, and e-mail questionnaires to a broader sample stratum, data on the ability of the tools, the techniques employed on 51 Lime Street and similar projects have been collated and statistically analysed to validate the reliability and relevance for future implementation. The result of the research will provide management teams with a practical alternative to existing planning methodologies. Construction planners will have alternative technique that can further enhance their role within the project team whilst increasing their ability to communicate the team’s vision to a wider audience, making them and the project more efficient and effective in the process. It has been proposed that clients insist on the use of 3D from the commencement of the design process so that this information can be passed downstream through the construction process and onto facilities management. Planners need to be able to communicate their requirements better and the 4D planning models provide both a more inclusive way of planning alongside a better communications medium in the form of moving images. A picture tells a thousand words.
- Full Text:
- Date Issued: 2007
- Authors: Allen, Christopher James
- Date: 2007
- Subjects: Construction industry -- Management , Construction industry -- Computer-aided design
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9698 , http://hdl.handle.net/10948/467 , http://hdl.handle.net/10948/d1011923 , Construction industry -- Management , Construction industry -- Computer-aided design
- Description: Construction Planning will increasingly play a more critical role within the realm of the Built Environment. Existing practices used to plan and communicate the construction process to be undertaken are failing to deliver the desired results for construction companies and clients alike. At a time of unprecedented growth in the industry around the world, which is leading to a general skills shortage, especially in management positions, construction planners are increasingly being asked to deal with more responsibility. As with other industries, technological improvement in the tools at their disposal is one way to address the inadequacies of the present situation. Increasingly, three dimensional design packages are being used to generate construction information which can then be used for quantities calculations, automated manufacturing processes and construction simulation. The latter forms the basis for their use in the process of planning, through new technologies being developed as virtual construction tools or 4D planning, the addition of time to the 3D model environment, but using the elements within the model as the basis for the construction programme. The benefit of using the design information to form the basis of the programme is that the interface tasks and logistical activities, as well as location related constraints, can be identified and then communicated to all levels within the construction team through a time based visual image. The purpose of this study is therefore to establish a scientifically analysed alternative method for the creation, review and delivery of construction programmes. In order to achieve the research objectives, three methodologies have been employed. Firstly, the literature review in the fields of planning including existing methodologies and previous research of 4D related techniques has been analysed. An overview of the perceived weaknesses to current practises and proposed solution will be explored and best case scenarios outlined and further investigated. Secondly, the 51 Lime Street project provides an environment in which the proposed 4D planning techniques have been implemented and the benefits of the process can, through observation / participation methodology, be validated. Thirdly, through interview questionnaires, with Lime St contractors and management, and e-mail questionnaires to a broader sample stratum, data on the ability of the tools, the techniques employed on 51 Lime Street and similar projects have been collated and statistically analysed to validate the reliability and relevance for future implementation. The result of the research will provide management teams with a practical alternative to existing planning methodologies. Construction planners will have alternative technique that can further enhance their role within the project team whilst increasing their ability to communicate the team’s vision to a wider audience, making them and the project more efficient and effective in the process. It has been proposed that clients insist on the use of 3D from the commencement of the design process so that this information can be passed downstream through the construction process and onto facilities management. Planners need to be able to communicate their requirements better and the 4D planning models provide both a more inclusive way of planning alongside a better communications medium in the form of moving images. A picture tells a thousand words.
- Full Text:
- Date Issued: 2007
The social and spatial organisation of the Greater kudu (Tragelaphus strepsiceros Pallas 1766) in the Andries Vosloo Kudu Reserve, Eastern Cape
- Authors: Allen-Rowlandson, T S
- Date: 1981
- Subjects: Greater kudu -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5614 , http://hdl.handle.net/10962/d1003120 , Greater kudu -- South Africa -- Eastern Cape
- Description: Methods of capture, marking and age determination in the field, were investigated. The density and structure of the population, individual movements and social relationships were determined. Aspects of reproduction examined included age at puberty, agespecific fecundity, calving intervals and seasonality. Temporal changes in the spatial and social organisation are discussed in relation to environmental conditions, reproduction and population structure. Factors influencing the fecundity, dynamics and grouping patterns within the population are considered.
- Full Text:
- Date Issued: 1981
- Authors: Allen-Rowlandson, T S
- Date: 1981
- Subjects: Greater kudu -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5614 , http://hdl.handle.net/10962/d1003120 , Greater kudu -- South Africa -- Eastern Cape
- Description: Methods of capture, marking and age determination in the field, were investigated. The density and structure of the population, individual movements and social relationships were determined. Aspects of reproduction examined included age at puberty, agespecific fecundity, calving intervals and seasonality. Temporal changes in the spatial and social organisation are discussed in relation to environmental conditions, reproduction and population structure. Factors influencing the fecundity, dynamics and grouping patterns within the population are considered.
- Full Text:
- Date Issued: 1981
An investigation of the equivalent circuit of a conductivity cell
- Authors: Allison, Francis Sutton
- Date: 1954
- Subjects: Electrolytic cells
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4508 , http://hdl.handle.net/10962/d1013376
- Description: ( i) A linear circuit is shown not to explain the behaviour of a conductivity cell towards a long rectangular pulse of amplitude less than the decomposition potential of the solution in the cell. (ii) It is shown that the flow of current through the cell is governed by diffusion to the electrode. The diffusion current expression is the familiar one used in the case of diffusion up to a plane micro-electrode, except that in this case the concentration in the layer next to the electrode is not zero, but only somewhat less than the bulk concentration. (iii) Except during a short initial period (less than 10 seconds), the resistance of the electrolytic cell varies directly with the square root of the time for which an e.m.f. (less than the decomposition potential) is applied to the cell, and inversely with the concentration difference between the electrode surface and the bulk of the solution.
- Full Text:
- Date Issued: 1954
- Authors: Allison, Francis Sutton
- Date: 1954
- Subjects: Electrolytic cells
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4508 , http://hdl.handle.net/10962/d1013376
- Description: ( i) A linear circuit is shown not to explain the behaviour of a conductivity cell towards a long rectangular pulse of amplitude less than the decomposition potential of the solution in the cell. (ii) It is shown that the flow of current through the cell is governed by diffusion to the electrode. The diffusion current expression is the familiar one used in the case of diffusion up to a plane micro-electrode, except that in this case the concentration in the layer next to the electrode is not zero, but only somewhat less than the bulk concentration. (iii) Except during a short initial period (less than 10 seconds), the resistance of the electrolytic cell varies directly with the square root of the time for which an e.m.f. (less than the decomposition potential) is applied to the cell, and inversely with the concentration difference between the electrode surface and the bulk of the solution.
- Full Text:
- Date Issued: 1954
Gypsum deposits associated with the Whitehill Formation (Ecca Group) in the Steytlerville-Jansenville Area, Southern Karoo, South Africa
- Authors: Almanza, Roberto Daniel
- Date: 2017
- Subjects: Gypsum -- South Africa Concretions -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/15292 , vital:28215
- Description: The Steyterville-Jansenville gypsum field is one of South Africa’s smaller deposits, yet plays host to several gypsum mines, both past and present. This study aims to deconstruct the processes involved in the precipitation of various quantities and grades of gypsum in the lower Ecca Group of the Karoo Supergroup. The calcium and sulphate ions required to form the gypsum mineral (CaSO4•2H2O) are derived from the mid- to lower-shale of the Whitehill Formation, which is carbonate- and pyrite-rich. Gypsum formation is dependent on the availability of pyrite as opposed to calcite, which is in abundance throughout the 30m thick, Early Ufimian (late Permian) Whitehill Formation. Weathered shale, which has been folded and faulted, forms the host environment in which gypsum has precipitated. Folding of the shale occurs as a series of large- and medium-scale anticlines and synclines that strike east to west. These structures, which formed during the Cape Orogeny indicate that stresses were exerted from the south-southwest towards the north-northeast. Folded calcite veins surrounded by amorphous pyrite, observed in thin section suggest that pyrite and calcite were precipitated together prior to a deformation event. Oxidation of pyrite following these deformation events results in the concentration of sulphides within the hinge zones of the folds (weakest zone) and this is where the larger gypsum deposits are found at the surface. Carbonate concretions in the Whitehill Formation up to 5m in length and 3m in width are common in the study area, and suggest a relationship with the deposition of the shale whereby calcium-rich nuclei grew in a concentric fashion during a non-depositional hiatus period. This period is also associated with a higher concentration of pyrite and could explain the occurrence of concretions together with adjacent gypsum-rich shale. Pyrite framboids observed under the Scanning Electron Microscope (SEM) provide evidence to suggest concentric growth of initially deposited microcrystals including nucleation and growth of nodules and concretions observed within the Whitehill Formation. Prerequisites for gypsum formation also include restricted drainage such as a pan, a clay layer in the drainage area and an arid climate where evaporation exceeds precipitation. The preferred surface conditions for gypsum formation would be low-lying areas which are surrounded by gently-sloping topography promoting the concentration of aqueous solutions in a calcite- and pyrite-rich area. Groundwater solution would initially dissolve the calcite and clay minerals, and pyrite and the quartz minerals would remain in the host rock. Areas with greater calcite and clay pores would accommodate more groundwater and thus promote a greater surface area for chemical reactions. This enhances the potential for the oxidation of pyrite to form sulphate ions, which can later combine with calcium ions to precipitate gypsum crystals. Alternatively, the oxidation of pyrite, which produces acidity, dissolves the carbonate host and the calcium- and sulphate-rich solution then precipitates gypsum. The combination of the structural and geomorphological processes is key to the formation of economic gypsum deposits. The potential for extensive gypsum reserves within the Steytlerville-Jansenville field remains valid, provided the target is located over a predominantly weathered Whitehill Formation outcrop, preferably in an area which has undergone extensive deformation (such as a fold hinge zone), and is favourable for the concentration of ground and surface water within a low-lying area.
- Full Text:
- Date Issued: 2017
- Authors: Almanza, Roberto Daniel
- Date: 2017
- Subjects: Gypsum -- South Africa Concretions -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/15292 , vital:28215
- Description: The Steyterville-Jansenville gypsum field is one of South Africa’s smaller deposits, yet plays host to several gypsum mines, both past and present. This study aims to deconstruct the processes involved in the precipitation of various quantities and grades of gypsum in the lower Ecca Group of the Karoo Supergroup. The calcium and sulphate ions required to form the gypsum mineral (CaSO4•2H2O) are derived from the mid- to lower-shale of the Whitehill Formation, which is carbonate- and pyrite-rich. Gypsum formation is dependent on the availability of pyrite as opposed to calcite, which is in abundance throughout the 30m thick, Early Ufimian (late Permian) Whitehill Formation. Weathered shale, which has been folded and faulted, forms the host environment in which gypsum has precipitated. Folding of the shale occurs as a series of large- and medium-scale anticlines and synclines that strike east to west. These structures, which formed during the Cape Orogeny indicate that stresses were exerted from the south-southwest towards the north-northeast. Folded calcite veins surrounded by amorphous pyrite, observed in thin section suggest that pyrite and calcite were precipitated together prior to a deformation event. Oxidation of pyrite following these deformation events results in the concentration of sulphides within the hinge zones of the folds (weakest zone) and this is where the larger gypsum deposits are found at the surface. Carbonate concretions in the Whitehill Formation up to 5m in length and 3m in width are common in the study area, and suggest a relationship with the deposition of the shale whereby calcium-rich nuclei grew in a concentric fashion during a non-depositional hiatus period. This period is also associated with a higher concentration of pyrite and could explain the occurrence of concretions together with adjacent gypsum-rich shale. Pyrite framboids observed under the Scanning Electron Microscope (SEM) provide evidence to suggest concentric growth of initially deposited microcrystals including nucleation and growth of nodules and concretions observed within the Whitehill Formation. Prerequisites for gypsum formation also include restricted drainage such as a pan, a clay layer in the drainage area and an arid climate where evaporation exceeds precipitation. The preferred surface conditions for gypsum formation would be low-lying areas which are surrounded by gently-sloping topography promoting the concentration of aqueous solutions in a calcite- and pyrite-rich area. Groundwater solution would initially dissolve the calcite and clay minerals, and pyrite and the quartz minerals would remain in the host rock. Areas with greater calcite and clay pores would accommodate more groundwater and thus promote a greater surface area for chemical reactions. This enhances the potential for the oxidation of pyrite to form sulphate ions, which can later combine with calcium ions to precipitate gypsum crystals. Alternatively, the oxidation of pyrite, which produces acidity, dissolves the carbonate host and the calcium- and sulphate-rich solution then precipitates gypsum. The combination of the structural and geomorphological processes is key to the formation of economic gypsum deposits. The potential for extensive gypsum reserves within the Steytlerville-Jansenville field remains valid, provided the target is located over a predominantly weathered Whitehill Formation outcrop, preferably in an area which has undergone extensive deformation (such as a fold hinge zone), and is favourable for the concentration of ground and surface water within a low-lying area.
- Full Text:
- Date Issued: 2017
An architecutre for the effective use of mobile devices in supporting contact learning
- Authors: Alnseerat, Nemr
- Date: 2014
- Subjects: Mobile communication systems in education , Educational technology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10490 , http://hdl.handle.net/10948/d1020079
- Description: The features and capacities of mobile devices offer a wide range of significant opportunities for providing learning content in workplaces and educational institutions. This new approach of teaching, called mobile learning, allows for the delivery of learning content on the move at any time. Mobile learning supports learning by producing learning content to learners in a modern and acceptable way. The number of mobile learning applications has increased rapidly in educational environments. There are, however, limited mobile learning applications that take advantage of mobile devices to support contact learning in the classroom environment. The aim of this research was to design a mobile learning architecture to effectively support contact learning in the classroom. The researcher investigated the historical and theoretical background of mobile learning and reported these findings. This included an overview of existing mobile learning architectures. After identifying their limitations, the researcher designed the Contact Instruction Mobile Learning Architecture (CIMLA) to facilitate the use of mobile devices in the classroom. The researcher developed the LiveLearning prototype based on the proposed architecture as a proof of concept. He conducted a usability evaluation in order to determine the usability of LiveLearning. The results indicated that the LiveLearning prototype is effective in supporting contact learning in the classroom.
- Full Text:
- Date Issued: 2014
- Authors: Alnseerat, Nemr
- Date: 2014
- Subjects: Mobile communication systems in education , Educational technology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10490 , http://hdl.handle.net/10948/d1020079
- Description: The features and capacities of mobile devices offer a wide range of significant opportunities for providing learning content in workplaces and educational institutions. This new approach of teaching, called mobile learning, allows for the delivery of learning content on the move at any time. Mobile learning supports learning by producing learning content to learners in a modern and acceptable way. The number of mobile learning applications has increased rapidly in educational environments. There are, however, limited mobile learning applications that take advantage of mobile devices to support contact learning in the classroom environment. The aim of this research was to design a mobile learning architecture to effectively support contact learning in the classroom. The researcher investigated the historical and theoretical background of mobile learning and reported these findings. This included an overview of existing mobile learning architectures. After identifying their limitations, the researcher designed the Contact Instruction Mobile Learning Architecture (CIMLA) to facilitate the use of mobile devices in the classroom. The researcher developed the LiveLearning prototype based on the proposed architecture as a proof of concept. He conducted a usability evaluation in order to determine the usability of LiveLearning. The results indicated that the LiveLearning prototype is effective in supporting contact learning in the classroom.
- Full Text:
- Date Issued: 2014
Multi-instrument observations of ionospheric irregularities over South Africa
- Authors: Amabayo, Emirant Bertillas
- Date: 2012
- Subjects: Ionosphere -- Research , Sudden ionospheric disturbances , Ionospheric storms , Solar activity , Sunspots
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5476 , http://hdl.handle.net/10962/d1005261 , Ionosphere -- Research , Sudden ionospheric disturbances , Ionospheric storms , Solar activity , Sunspots
- Description: The occurrence of mid-latitude spread F (SF) over South Africa has not been extensively studied since the installation of the DPS-4 digisondes at Madimbo (30.88◦E, 22.38◦S), Grahamstown (33.32◦S, 26.50◦E) and Louisvale (28.51◦S, 21.24◦E). This study is intended to quantify the probability of the occurrence of F region disturbances associated with ionospheric spread F (SF) and L-band scintillation over South Africa. This study used available ionosonde data for 8 years (2000-2008) from the three South African stations. The SF events were identified manually on ionograms and grouped for further statistical analysis into frequency SF (FSF), range SF (RSF) and mixed SF (MSF). The results show that the diurnal pattern of SF occurrence peaks strongly between 23:00 and 00:00 UT. This pattern is true for all seasons and types of SF at Madimbo and Grahamstown during 2001 and 2005, except for RSF which had peaks during autumn and spring during 2001 at Madimbo. The probability of both MSF and FSF tends to increase with decreasing sunspot number (SSN), with a peak in 2005 (a moderate solar activity period). The seasonal peaks of MSF and FSF are more frequent during winter months at both Madimbo and Grahamstown. In this study SF was evident in ∼ 0.03% and ∼ 0.06% of the available ionograms at Madimbo and Grahamstown respectively during the eight year period. The presence of ionospheric irregularities associated with SF and scintillation was investigated using data from selected Global Positioning System (GPS) receiver stations distributed across South Africa. The results, based on GPS total electron content (TEC) and ionosonde measurements, show that SF over this region can most likely be attributed to travelling ionospheric disturbances (TIDs), caused by gravity waves (GWs) and neutral wind composition changes. The GWs were mostly associated with geomagnetic storms and sub-storms that occurred during periods of high and moderate solar activity (2001-2005). SF occurrence during the low solar activity period (2006-2008)can probably be attributed to neutral wind composition changes.
- Full Text:
- Date Issued: 2012
- Authors: Amabayo, Emirant Bertillas
- Date: 2012
- Subjects: Ionosphere -- Research , Sudden ionospheric disturbances , Ionospheric storms , Solar activity , Sunspots
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5476 , http://hdl.handle.net/10962/d1005261 , Ionosphere -- Research , Sudden ionospheric disturbances , Ionospheric storms , Solar activity , Sunspots
- Description: The occurrence of mid-latitude spread F (SF) over South Africa has not been extensively studied since the installation of the DPS-4 digisondes at Madimbo (30.88◦E, 22.38◦S), Grahamstown (33.32◦S, 26.50◦E) and Louisvale (28.51◦S, 21.24◦E). This study is intended to quantify the probability of the occurrence of F region disturbances associated with ionospheric spread F (SF) and L-band scintillation over South Africa. This study used available ionosonde data for 8 years (2000-2008) from the three South African stations. The SF events were identified manually on ionograms and grouped for further statistical analysis into frequency SF (FSF), range SF (RSF) and mixed SF (MSF). The results show that the diurnal pattern of SF occurrence peaks strongly between 23:00 and 00:00 UT. This pattern is true for all seasons and types of SF at Madimbo and Grahamstown during 2001 and 2005, except for RSF which had peaks during autumn and spring during 2001 at Madimbo. The probability of both MSF and FSF tends to increase with decreasing sunspot number (SSN), with a peak in 2005 (a moderate solar activity period). The seasonal peaks of MSF and FSF are more frequent during winter months at both Madimbo and Grahamstown. In this study SF was evident in ∼ 0.03% and ∼ 0.06% of the available ionograms at Madimbo and Grahamstown respectively during the eight year period. The presence of ionospheric irregularities associated with SF and scintillation was investigated using data from selected Global Positioning System (GPS) receiver stations distributed across South Africa. The results, based on GPS total electron content (TEC) and ionosonde measurements, show that SF over this region can most likely be attributed to travelling ionospheric disturbances (TIDs), caused by gravity waves (GWs) and neutral wind composition changes. The GWs were mostly associated with geomagnetic storms and sub-storms that occurred during periods of high and moderate solar activity (2001-2005). SF occurrence during the low solar activity period (2006-2008)can probably be attributed to neutral wind composition changes.
- Full Text:
- Date Issued: 2012
A natural user interface architecture using gestures to facilitate the detection of fundamental movement skills
- Authors: Amanzi, Richard
- Date: 2015
- Subjects: Human activity recognition , Human-computer interaction
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/6204 , vital:21055
- Description: Fundamental movement skills (FMSs) are considered to be one of the essential phases of motor skill development. The proper development of FMSs allows children to participate in more advanced forms of movements and sports. To be able to perform an FMS correctly, children need to learn the right way of performing it. By making use of technology, a system can be developed that can help facilitate the learning of FMSs. The objective of the research was to propose an effective natural user interface (NUI) architecture for detecting FMSs using the Kinect. In order to achieve the stated objective, an investigation into FMSs and the challenges faced when teaching them was presented. An investigation into NUIs was also presented including the merits of the Kinect as the most appropriate device to be used to facilitate the detection of an FMS. An NUI architecture was proposed that uses the Kinect to facilitate the detection of an FMS. A framework was implemented from the design of the architecture. The successful implementation of the framework provides evidence that the design of the proposed architecture is feasible. An instance of the framework incorporating the jump FMS was used as a case study in the development of a prototype that detects the correct and incorrect performance of a jump. The evaluation of the prototype proved the following: - The developed prototype was effective in detecting the correct and incorrect performance of the jump FMS; and - The implemented framework was robust for the incorporation of an FMS. The successful implementation of the prototype shows that an effective NUI architecture using the Kinect can be used to facilitate the detection of FMSs. The proposed architecture provides a structured way of developing a system using the Kinect to facilitate the detection of FMSs. This allows developers to add future FMSs to the system. This dissertation therefore makes the following contributions: - An experimental design to evaluate the effectiveness of a prototype that detects FMSs - A robust framework that incorporates FMSs; and - An effective NUI architecture to facilitate the detection of fundamental movement skills using the Kinect.
- Full Text:
- Date Issued: 2015
- Authors: Amanzi, Richard
- Date: 2015
- Subjects: Human activity recognition , Human-computer interaction
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/6204 , vital:21055
- Description: Fundamental movement skills (FMSs) are considered to be one of the essential phases of motor skill development. The proper development of FMSs allows children to participate in more advanced forms of movements and sports. To be able to perform an FMS correctly, children need to learn the right way of performing it. By making use of technology, a system can be developed that can help facilitate the learning of FMSs. The objective of the research was to propose an effective natural user interface (NUI) architecture for detecting FMSs using the Kinect. In order to achieve the stated objective, an investigation into FMSs and the challenges faced when teaching them was presented. An investigation into NUIs was also presented including the merits of the Kinect as the most appropriate device to be used to facilitate the detection of an FMS. An NUI architecture was proposed that uses the Kinect to facilitate the detection of an FMS. A framework was implemented from the design of the architecture. The successful implementation of the framework provides evidence that the design of the proposed architecture is feasible. An instance of the framework incorporating the jump FMS was used as a case study in the development of a prototype that detects the correct and incorrect performance of a jump. The evaluation of the prototype proved the following: - The developed prototype was effective in detecting the correct and incorrect performance of the jump FMS; and - The implemented framework was robust for the incorporation of an FMS. The successful implementation of the prototype shows that an effective NUI architecture using the Kinect can be used to facilitate the detection of FMSs. The proposed architecture provides a structured way of developing a system using the Kinect to facilitate the detection of FMSs. This allows developers to add future FMSs to the system. This dissertation therefore makes the following contributions: - An experimental design to evaluate the effectiveness of a prototype that detects FMSs - A robust framework that incorporates FMSs; and - An effective NUI architecture to facilitate the detection of fundamental movement skills using the Kinect.
- Full Text:
- Date Issued: 2015
Feeding ecology and diet shift of long-beaked common dolphins Delphinus Capensis (Gray 1828) incidentally caught in anti-shark nets off Kwazulu-Natal, South Africa
- Authors: Ambrose, Shan Taryn
- Date: 2011
- Subjects: Common dolphin -- South Africa -- Kwazulu-Natal , Common dolphin -- Food -- South Africa -- Kwazulu-Natal , Common dolphin -- Ecology -- South Africa -- Kwazulu-Natal , Sardinops sagax -- South Africa -- Kwazulu-Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5697 , http://hdl.handle.net/10962/d1005383 , Common dolphin -- South Africa -- Kwazulu-Natal , Common dolphin -- Food -- South Africa -- Kwazulu-Natal , Common dolphin -- Ecology -- South Africa -- Kwazulu-Natal , Sardinops sagax -- South Africa -- Kwazulu-Natal
- Description: The long-beaked common dolphin, Delphinus capensis (Gray 1828), is one of the most enigmatic predators feeding in the annual sardine run (Sardinops sagax) off the coast of KwaZulu-Natal (KZN), South Africa. In recent years, unpredictable inter-annual variations in the timing, spatial extent and intensity of the sardine run have been documented, possibly resulting in changes in the suite of prey available to the common dolphin during winter. Although the diets of a number of predators during the sardine run have been studied in detail (e.g. sharks and flying seabirds), little is known about the diet of long-beaked common dolphins during this period. Each year, a low number of common dolphins are incidentally caught in the anti-shark nets in the waters of KwaZulu-Natal. These captures provide a valuable source of data on selected aspects of the ecology of the long-beaked common dolphins along the KwaZulu-Natal coastline. The objective of this study was to provide new dietary data for the common dolphins feeding in the waters of KwaZulu-Natal during winter over the period 2000 to 2009, as well as to determine if any dietary changes had taken place since the common dolphin diet was last assessed, over 15 years ago. Stomach contents from 95 common dolphins (55 females, 40 males) caught between 2000 and 2009 were analysed and compared to historical data from dolphins caught between 1974 and 1992. Mesopelagic fish and squid dominated the diet, with 23 fish and 5 squid species represented in adult dolphins. Multidimensional Scaling (MDS) indicated that there was no resource partitioning between adult male and female dolphins. Numerical analyses indicated that there was a shift in the principal prey species consumed by the dolphins over the past decade, particularly during the winter. Prior to 1992, sardine comprised up to 49% of the total stomach contents, while chub mackerel (Scomber japonicus) was the dominant prey item (66% by mass) recorded in the stomach contents over the period 2000 to 2009. The shift in the relative contributions of sardine and mackerel in the diets of the dolphin appeared to correspond to fluctuations in the availability of the two principal prey species. Between 2000 and 2009, the diversity of the dolphins' diets was highest during the sardine run, reflecting the presence of a wide suite of predatory teleosts in the waters of KwaZulu-Natal during the annual sardine run. Conversely, prior to 2000, the diet was dominated by sardine during the peak of the sardine run, whilst diet diversity increased after this period. Apart from sardine and chub mackerel, elf (Pomatomus saltatrix), maasbanker (Trachurus delagoa), strepie (Sarpa salpa) and flying fish (Exocoetid sp.) also formed important components of the diet both prior to 1992, and over the last decade. Blubber thickness was assessed as an indicator of animal condition. No significant change in blubber total weight (R² = 0.0016, N = 185), nor dorsal, lateral or ventral blubber thickness (R² = 0.3146, R² = 0.0003, and R² = 0.0003 respectively, N = 78) was seen over the last 30 years (1970 to 2009). Results of stable isotope analyses conducted on tissue derived from the teeth of D. capensis indicated that there has been no significant shift in the trophic position (δ¹⁵N) and potential prey consumed (δ¹³C) over the corresponding period. These data would suggest that the long-beaked common dolphins along the KwaZulu-Natal coastline can be considered as opportunistic predators generally consuming the most abundant prey species available locally. As common dolphins feed opportunistically, this dietary shift appears to indicate changes in the shoaling characteristics of the most abundant fish prey in KwaZulu-Natal during winter. Given the “Data Deficient” status of the long-beaked common dolphin on the IUCN Red Data List, and the strong climatic forcing of the sardine run, such dietary data have important implications for their conservation in the light of expanding fisheries and climate change.
- Full Text:
- Date Issued: 2011
- Authors: Ambrose, Shan Taryn
- Date: 2011
- Subjects: Common dolphin -- South Africa -- Kwazulu-Natal , Common dolphin -- Food -- South Africa -- Kwazulu-Natal , Common dolphin -- Ecology -- South Africa -- Kwazulu-Natal , Sardinops sagax -- South Africa -- Kwazulu-Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5697 , http://hdl.handle.net/10962/d1005383 , Common dolphin -- South Africa -- Kwazulu-Natal , Common dolphin -- Food -- South Africa -- Kwazulu-Natal , Common dolphin -- Ecology -- South Africa -- Kwazulu-Natal , Sardinops sagax -- South Africa -- Kwazulu-Natal
- Description: The long-beaked common dolphin, Delphinus capensis (Gray 1828), is one of the most enigmatic predators feeding in the annual sardine run (Sardinops sagax) off the coast of KwaZulu-Natal (KZN), South Africa. In recent years, unpredictable inter-annual variations in the timing, spatial extent and intensity of the sardine run have been documented, possibly resulting in changes in the suite of prey available to the common dolphin during winter. Although the diets of a number of predators during the sardine run have been studied in detail (e.g. sharks and flying seabirds), little is known about the diet of long-beaked common dolphins during this period. Each year, a low number of common dolphins are incidentally caught in the anti-shark nets in the waters of KwaZulu-Natal. These captures provide a valuable source of data on selected aspects of the ecology of the long-beaked common dolphins along the KwaZulu-Natal coastline. The objective of this study was to provide new dietary data for the common dolphins feeding in the waters of KwaZulu-Natal during winter over the period 2000 to 2009, as well as to determine if any dietary changes had taken place since the common dolphin diet was last assessed, over 15 years ago. Stomach contents from 95 common dolphins (55 females, 40 males) caught between 2000 and 2009 were analysed and compared to historical data from dolphins caught between 1974 and 1992. Mesopelagic fish and squid dominated the diet, with 23 fish and 5 squid species represented in adult dolphins. Multidimensional Scaling (MDS) indicated that there was no resource partitioning between adult male and female dolphins. Numerical analyses indicated that there was a shift in the principal prey species consumed by the dolphins over the past decade, particularly during the winter. Prior to 1992, sardine comprised up to 49% of the total stomach contents, while chub mackerel (Scomber japonicus) was the dominant prey item (66% by mass) recorded in the stomach contents over the period 2000 to 2009. The shift in the relative contributions of sardine and mackerel in the diets of the dolphin appeared to correspond to fluctuations in the availability of the two principal prey species. Between 2000 and 2009, the diversity of the dolphins' diets was highest during the sardine run, reflecting the presence of a wide suite of predatory teleosts in the waters of KwaZulu-Natal during the annual sardine run. Conversely, prior to 2000, the diet was dominated by sardine during the peak of the sardine run, whilst diet diversity increased after this period. Apart from sardine and chub mackerel, elf (Pomatomus saltatrix), maasbanker (Trachurus delagoa), strepie (Sarpa salpa) and flying fish (Exocoetid sp.) also formed important components of the diet both prior to 1992, and over the last decade. Blubber thickness was assessed as an indicator of animal condition. No significant change in blubber total weight (R² = 0.0016, N = 185), nor dorsal, lateral or ventral blubber thickness (R² = 0.3146, R² = 0.0003, and R² = 0.0003 respectively, N = 78) was seen over the last 30 years (1970 to 2009). Results of stable isotope analyses conducted on tissue derived from the teeth of D. capensis indicated that there has been no significant shift in the trophic position (δ¹⁵N) and potential prey consumed (δ¹³C) over the corresponding period. These data would suggest that the long-beaked common dolphins along the KwaZulu-Natal coastline can be considered as opportunistic predators generally consuming the most abundant prey species available locally. As common dolphins feed opportunistically, this dietary shift appears to indicate changes in the shoaling characteristics of the most abundant fish prey in KwaZulu-Natal during winter. Given the “Data Deficient” status of the long-beaked common dolphin on the IUCN Red Data List, and the strong climatic forcing of the sardine run, such dietary data have important implications for their conservation in the light of expanding fisheries and climate change.
- Full Text:
- Date Issued: 2011
In silico analysis of plasmodium falciparum Hsp70-x for potential binding sites and hits
- Authors: Amusengeri, Arnold
- Date: 2017
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59136 , vital:27435
- Description: Restricted access-thesis embargoed for 1 year - release date April 2019
- Full Text:
- Date Issued: 2017
- Authors: Amusengeri, Arnold
- Date: 2017
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59136 , vital:27435
- Description: Restricted access-thesis embargoed for 1 year - release date April 2019
- Full Text:
- Date Issued: 2017
A Systematic Visualisation Framework for Radio-Imaging Pipelines
- Authors: Andati, Lexy Acherwa Livoyi
- Date: 2021-04
- Subjects: Radio interferometers , Radio astronomy -- Data processing , Radio astronomy -- Data processing -- Software , Jupyter
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177338 , vital:42812
- Description: Pipelines for calibration and imaging of radio interferometric data produce many intermediate images and other data products (gain tables, etc.) These often contain valuable information about the quality of the data and the calibration, and can provide the user with valuable insights, if only visualised in the right way. However, the deluge of data that we’re experiencing with modern instruments means that most of these products are never looked at, and only the final images and data products are examined. Furthermore, the variety of imaging algorithms currently available, and the range of their options, means that very different results can be produced from the same set of original data. Proper understanding of this requires a systematic comparison that can be carried out both by individual users locally, and by the community globally. We address both problems by developing a systematic visualisation framework based around Jupyter notebooks, enriched with interactive plots based on the Bokeh and Datashader visualisation libraries. , Thesis (MSc) -- Faculty of Science, Department of Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Andati, Lexy Acherwa Livoyi
- Date: 2021-04
- Subjects: Radio interferometers , Radio astronomy -- Data processing , Radio astronomy -- Data processing -- Software , Jupyter
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177338 , vital:42812
- Description: Pipelines for calibration and imaging of radio interferometric data produce many intermediate images and other data products (gain tables, etc.) These often contain valuable information about the quality of the data and the calibration, and can provide the user with valuable insights, if only visualised in the right way. However, the deluge of data that we’re experiencing with modern instruments means that most of these products are never looked at, and only the final images and data products are examined. Furthermore, the variety of imaging algorithms currently available, and the range of their options, means that very different results can be produced from the same set of original data. Proper understanding of this requires a systematic comparison that can be carried out both by individual users locally, and by the community globally. We address both problems by developing a systematic visualisation framework based around Jupyter notebooks, enriched with interactive plots based on the Bokeh and Datashader visualisation libraries. , Thesis (MSc) -- Faculty of Science, Department of Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-04
Growth and photosynthetic responses of Acacia (Vachellia) seedlings to atmospheric CO2 increased from glacial to current concentrations: underlying mechanisms and ecological implications
- Authors: Anderson, Bruce Maurice
- Date: 2020
- Subjects: Acacia vachellia , Acacia vachellia -- Growth , Acacia -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/138182 , vital:37604
- Description: The African Acacia species Vachellia karroo, V. robusta, V. nilotica, and V. tortilis are some of the most invasive species implicated in bush encroachment and woody thickening of historically open savannas in southern Africa. This is partially explained by historic increases in atmospheric CO2 concentrations, which are proposed to have promoted the growth and survivorship of C3 tree seedlings relative to C4 grasses. However, the uniformity of CO2 responsiveness and differences among Vachellia species remain largely undetermined. Here we investigate the growth and photosynthetic responses of four Vachellia species, all implicated in woody encroachment, but originating from distinct climatic niches. Exposing these species to a range of sub-ambient CO2 concentrations (12 – 40 Pa) showed that V. karroo, V. robusta, V. nilotica and V. tortilis all responded strongly and fairly consistently to increasing CO2 concentrations, acting as a ‘functional type’ despite being selected from different geographic regions and having different climatic niches. Combined average net CO2 assimilation rates increased by 130% despite significant, but low levels of down-regulation and decreased stomatal conductance. The increased photosynthetic rates stimulated growth and biomass production in all compartments, with no significant differences in interspecific above and below ground allocation. Growth rates and dry biomass increased by 50% and 186%, respectively, while leaf level water use efficiency (ratio of net CO2 assimilation rate to transpiration rate) increased by an average of 218%. When this was scaled to the whole plant level, this stimulation was decreased to 80%. The decrease was the result of the CO2 stimulated increase in canopy areas, which increased leaf area for water loss. The seedlings’ total number of spinescent physical defenses, as well as the average mass and spine mass fraction also increased with rising CO2. These thicker spines could act as better deterrents against vertebrate browsers. Spine density was unchanged, however, showing that the increased spine numbers were associated with larger seedlings at higher CO2 rather than an increase in the number of spines per stem length. The stimulatory effects of increasing CO2 concentrations since the last glacial maximum and resultant increases in seedling growth and biomass are likely to have had important consequences for the survival and establishment of Acacia seedlings. Tolerance of drought and disturbance has been related to seedling size, hence stimulating the growth rate could confer disturbance tolerance and this tolerance would develop more rapidly with increasing CO2 concentrations. Furthermore, increased nitrogen and water use efficiency have the potential to support seedling establishment in environments where these resources would otherwise be limited at lower atmospheric CO2 concentrations. Resulting in a larger proportion of CO2 fertilization responsive woody seedlings surviving the seedling size classes, and persisting within historically open savannas. Where interspecific differences occurred they are likely to have arisen from adaptation to specific climates where these species are native and selection would have been driven by factors such climate, resource availability, levels of disturbance and competitive interactions. V. karroo had the highest growth rates and strong CO2 driven increases in biomass accumulation, despite having the lowest inherent photosynthetic rates. V. karroo also had the lowest increase in water use efficiency and high transpiration rates could potentially increase access to soil nutrients through mass flow. This species had the highest mean spine mass and showed significant increases in spine mass fraction at elevated CO2 concentrations, which may be important for deterring herbivores. V. robusta’s distribution to the mesic east coast of Africa suggests that water is an important limitation to its distribution. Hence, the CO2 stimulated increase in water use efficiency at both leaf and whole canopy level allows speculation that this may be an important driver of this species’ range expansion, which might continue if increasing levels of CO2 continue to promote water use efficiency. V. nilotica occupies a broad range of habitats, inhabiting large areas of the subtropics both north and south of the equator, with the strongest climatic correlates being the precipitation of the wettest quarter followed by high temperature seasonality. In response to increasing CO2, V. nilotica showed overall strong increases in growth, water use efficiency, and physical defenses. These responses may explain why V. nilotica has been such a successful encroacher in a broad range of habitats where limitations are likely to include multiple climatic factors and disturbances. V. tortilis has the widest distribution of all the species studied, covering broad ranges of Africa and only being excluded from the wettest parts of the equator and driest parts of the deserts. In these experiments this species showed the lowest biomass responsiveness to CO2, but had especially large increases in water use efficiency at both the leaf and canopy level. This may have been an important driver for this species’ encroachment into the more arid parts of its distribution, however this link will need to be verified with further experimentation.
- Full Text:
- Date Issued: 2020
- Authors: Anderson, Bruce Maurice
- Date: 2020
- Subjects: Acacia vachellia , Acacia vachellia -- Growth , Acacia -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/138182 , vital:37604
- Description: The African Acacia species Vachellia karroo, V. robusta, V. nilotica, and V. tortilis are some of the most invasive species implicated in bush encroachment and woody thickening of historically open savannas in southern Africa. This is partially explained by historic increases in atmospheric CO2 concentrations, which are proposed to have promoted the growth and survivorship of C3 tree seedlings relative to C4 grasses. However, the uniformity of CO2 responsiveness and differences among Vachellia species remain largely undetermined. Here we investigate the growth and photosynthetic responses of four Vachellia species, all implicated in woody encroachment, but originating from distinct climatic niches. Exposing these species to a range of sub-ambient CO2 concentrations (12 – 40 Pa) showed that V. karroo, V. robusta, V. nilotica and V. tortilis all responded strongly and fairly consistently to increasing CO2 concentrations, acting as a ‘functional type’ despite being selected from different geographic regions and having different climatic niches. Combined average net CO2 assimilation rates increased by 130% despite significant, but low levels of down-regulation and decreased stomatal conductance. The increased photosynthetic rates stimulated growth and biomass production in all compartments, with no significant differences in interspecific above and below ground allocation. Growth rates and dry biomass increased by 50% and 186%, respectively, while leaf level water use efficiency (ratio of net CO2 assimilation rate to transpiration rate) increased by an average of 218%. When this was scaled to the whole plant level, this stimulation was decreased to 80%. The decrease was the result of the CO2 stimulated increase in canopy areas, which increased leaf area for water loss. The seedlings’ total number of spinescent physical defenses, as well as the average mass and spine mass fraction also increased with rising CO2. These thicker spines could act as better deterrents against vertebrate browsers. Spine density was unchanged, however, showing that the increased spine numbers were associated with larger seedlings at higher CO2 rather than an increase in the number of spines per stem length. The stimulatory effects of increasing CO2 concentrations since the last glacial maximum and resultant increases in seedling growth and biomass are likely to have had important consequences for the survival and establishment of Acacia seedlings. Tolerance of drought and disturbance has been related to seedling size, hence stimulating the growth rate could confer disturbance tolerance and this tolerance would develop more rapidly with increasing CO2 concentrations. Furthermore, increased nitrogen and water use efficiency have the potential to support seedling establishment in environments where these resources would otherwise be limited at lower atmospheric CO2 concentrations. Resulting in a larger proportion of CO2 fertilization responsive woody seedlings surviving the seedling size classes, and persisting within historically open savannas. Where interspecific differences occurred they are likely to have arisen from adaptation to specific climates where these species are native and selection would have been driven by factors such climate, resource availability, levels of disturbance and competitive interactions. V. karroo had the highest growth rates and strong CO2 driven increases in biomass accumulation, despite having the lowest inherent photosynthetic rates. V. karroo also had the lowest increase in water use efficiency and high transpiration rates could potentially increase access to soil nutrients through mass flow. This species had the highest mean spine mass and showed significant increases in spine mass fraction at elevated CO2 concentrations, which may be important for deterring herbivores. V. robusta’s distribution to the mesic east coast of Africa suggests that water is an important limitation to its distribution. Hence, the CO2 stimulated increase in water use efficiency at both leaf and whole canopy level allows speculation that this may be an important driver of this species’ range expansion, which might continue if increasing levels of CO2 continue to promote water use efficiency. V. nilotica occupies a broad range of habitats, inhabiting large areas of the subtropics both north and south of the equator, with the strongest climatic correlates being the precipitation of the wettest quarter followed by high temperature seasonality. In response to increasing CO2, V. nilotica showed overall strong increases in growth, water use efficiency, and physical defenses. These responses may explain why V. nilotica has been such a successful encroacher in a broad range of habitats where limitations are likely to include multiple climatic factors and disturbances. V. tortilis has the widest distribution of all the species studied, covering broad ranges of Africa and only being excluded from the wettest parts of the equator and driest parts of the deserts. In these experiments this species showed the lowest biomass responsiveness to CO2, but had especially large increases in water use efficiency at both the leaf and canopy level. This may have been an important driver for this species’ encroachment into the more arid parts of its distribution, however this link will need to be verified with further experimentation.
- Full Text:
- Date Issued: 2020
A hybrid approach to beach erosion mitigation and amenity enhancement, St Francis Bay, South Africa
- Authors: Anderson, Dylan Rory
- Date: 2008
- Subjects: Beach erosion -- South Africa -- St Francis Bay , Shore protection -- South Africa -- St Francis Bay , Restoration ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10611 , http://hdl.handle.net/10948/d1008192 , Beach erosion -- South Africa -- St Francis Bay , Shore protection -- South Africa -- St Francis Bay , Restoration ecology
- Description: The St Francis Bay beach has experienced chronic erosion over the past three decades. This erosion can largely be attributed to the stabilisation of a large coastal dunefield which contributed +/- 80 percent of the sand supply to St Francis Bay. Stabilisation began in 1975 initially using plant cuttings and followed by the development of the Santareme holiday suburb resulting in complete stabilisation by 1985. Effects were felt from the late 1970‟s and since then the beach has retreated at between 0.5 - 3 m.yr-1. Erosion has encroached on beachfront properties since the early 1990‟s, leading to the placement of 3-4 m high unsightly rock revetments along much of the beach. Where properly maintained these structures have proved successful in protecting the properties behind, however exacerbated erosion of areas in front and adjacent to these structures is evident. Currently no dry beach is present at high tide for most of the year, leading to a significant reduction in beach amenity value. Several technical studies to investigate remediation of this beach erosion problem have been conducted since the early 1990‟s. This study includes investigations into the processes and dynamics of the existing environment and evaluation of the effectiveness and impacts of several elements of a hybrid approach to coastal protection and amenity enhancement for St Francis Bay beach. This proposal incorporated: Multi-Purpose Reefs (MPR‟s) offshore, for coastal protection and amenity enhancement in terms of surfing; beach nourishment with sand from the Kromme Estuary and dune rehabilitation with appropriate native sand binding species. Extensive fieldwork and data collection were conducted, this included: a series of bathymetric surveys; diving surveys and a helicopter flight; sediment sampling; beach profiling and deployment of a wave/current meter. Analysis of these data provided a greater understanding of the existing environment and dynamics of St Francis Bay and provided reliable inputs for numerical modelling. Numerical and physical modelling was conducted to assess the existing processes and conduct MPR design testing. In addition calibrated hydrodynamic modelling of the Kromme Estuary was conducted in order to assess the impacts of sand extraction from the large sand banks within the mouth of the Kromme Estuary for use as beach nourishment. Comparison of bathymetric survey data collected by the author in 2005/06 with survey data collected by the South African Navy Hydrographic Office (SANHO) in 1952 suggest a major loss of sand from the bay, with a volume difference of some 8.8 X 106 m3 calculated. Greater losses were measured between 10-15 m water depths, with shallow areas of +/- 5 m water depth, remaining more stable. This can be attributed to the presence of shallow reef and rocky substrate through much of the bay at this depth range. Monthly RTK GPS survey data from September 2006 to September 2007 indicates a total loss of 40 000 m3 over this period with the greatest losses measured along the northern part of the beach. The greatest losses were measured after large long period waves from a southerly to south-easterly direction occurred in conjunction with equinox tides in mid March 2007. Sediment sampling at over 100 locations within the bay indicated a high percentage of reef (26 percent) and fairly consistent grain size in the fine to medium size class throughout much of the beach, bay and large sand bank within the estuary. While the majority of the South African Coast is exposed to the predominant south westerly winds and waves, St Francis Bay‟s orientation means that waves from a south easterly to easterly direction dominate. The results of the detailed numerical modelling of the hydrodynamics agree with previous calculations and modelling results which concluded that strong unidirectional longshore currents occur along the headland due to the oblique angle of wave incidence and the close to parallel angle of wave incidence along the beach leads to weak longshore currents of variable direction. Erosion along St Francis Bay beach is a result of cross-shore erosion due to large waves from a southerly to easterly direction. Detached breakwaters are the most effective form of coastal protection in these environments and MPR‟s offer additional benefits over traditional breakwater structures. Results of empirical calculations and numerical modelling indicate that the MPR‟s will provide effective coastal protection through the processes of wave dissipation, wave rotation, salient formation and alteration of nearshore circulation. Physical modelling results allowed the MPR design to be assessed and refined in terms of surfing amenity enhancement and construction constraints. In addition numerical modelling results indicate that impacts due to the extraction of up to 600 000 m3 of sand from the lower Kromme Estuary result in highly localised velocity reduction, mainly limited to the extraction areas. The calculated rate of sediment influx into the lower Kromme Estuary indicates that limited extraction, in the order of 20 000 – 40 000 m3 per year, should be sustainable in the long term. Sedimentation of the lower estuary over recent years has had negative recreational and ecological impacts, through reduced navigability and water exchange respectively. Therefore both the estuary and beach systems prove to benefit from this approach. Although not investigated in detail as part of this study, evidence from numerous projects worldwide indicates that foredunes help to trap wind-blown sand on the beach and form a buffer to storm erosion, therefore dune rehabilitation with native sand-binding plant species was recommended as the third element of the proposed remediation of St Francis Bay beach.
- Full Text:
- Date Issued: 2008
- Authors: Anderson, Dylan Rory
- Date: 2008
- Subjects: Beach erosion -- South Africa -- St Francis Bay , Shore protection -- South Africa -- St Francis Bay , Restoration ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10611 , http://hdl.handle.net/10948/d1008192 , Beach erosion -- South Africa -- St Francis Bay , Shore protection -- South Africa -- St Francis Bay , Restoration ecology
- Description: The St Francis Bay beach has experienced chronic erosion over the past three decades. This erosion can largely be attributed to the stabilisation of a large coastal dunefield which contributed +/- 80 percent of the sand supply to St Francis Bay. Stabilisation began in 1975 initially using plant cuttings and followed by the development of the Santareme holiday suburb resulting in complete stabilisation by 1985. Effects were felt from the late 1970‟s and since then the beach has retreated at between 0.5 - 3 m.yr-1. Erosion has encroached on beachfront properties since the early 1990‟s, leading to the placement of 3-4 m high unsightly rock revetments along much of the beach. Where properly maintained these structures have proved successful in protecting the properties behind, however exacerbated erosion of areas in front and adjacent to these structures is evident. Currently no dry beach is present at high tide for most of the year, leading to a significant reduction in beach amenity value. Several technical studies to investigate remediation of this beach erosion problem have been conducted since the early 1990‟s. This study includes investigations into the processes and dynamics of the existing environment and evaluation of the effectiveness and impacts of several elements of a hybrid approach to coastal protection and amenity enhancement for St Francis Bay beach. This proposal incorporated: Multi-Purpose Reefs (MPR‟s) offshore, for coastal protection and amenity enhancement in terms of surfing; beach nourishment with sand from the Kromme Estuary and dune rehabilitation with appropriate native sand binding species. Extensive fieldwork and data collection were conducted, this included: a series of bathymetric surveys; diving surveys and a helicopter flight; sediment sampling; beach profiling and deployment of a wave/current meter. Analysis of these data provided a greater understanding of the existing environment and dynamics of St Francis Bay and provided reliable inputs for numerical modelling. Numerical and physical modelling was conducted to assess the existing processes and conduct MPR design testing. In addition calibrated hydrodynamic modelling of the Kromme Estuary was conducted in order to assess the impacts of sand extraction from the large sand banks within the mouth of the Kromme Estuary for use as beach nourishment. Comparison of bathymetric survey data collected by the author in 2005/06 with survey data collected by the South African Navy Hydrographic Office (SANHO) in 1952 suggest a major loss of sand from the bay, with a volume difference of some 8.8 X 106 m3 calculated. Greater losses were measured between 10-15 m water depths, with shallow areas of +/- 5 m water depth, remaining more stable. This can be attributed to the presence of shallow reef and rocky substrate through much of the bay at this depth range. Monthly RTK GPS survey data from September 2006 to September 2007 indicates a total loss of 40 000 m3 over this period with the greatest losses measured along the northern part of the beach. The greatest losses were measured after large long period waves from a southerly to south-easterly direction occurred in conjunction with equinox tides in mid March 2007. Sediment sampling at over 100 locations within the bay indicated a high percentage of reef (26 percent) and fairly consistent grain size in the fine to medium size class throughout much of the beach, bay and large sand bank within the estuary. While the majority of the South African Coast is exposed to the predominant south westerly winds and waves, St Francis Bay‟s orientation means that waves from a south easterly to easterly direction dominate. The results of the detailed numerical modelling of the hydrodynamics agree with previous calculations and modelling results which concluded that strong unidirectional longshore currents occur along the headland due to the oblique angle of wave incidence and the close to parallel angle of wave incidence along the beach leads to weak longshore currents of variable direction. Erosion along St Francis Bay beach is a result of cross-shore erosion due to large waves from a southerly to easterly direction. Detached breakwaters are the most effective form of coastal protection in these environments and MPR‟s offer additional benefits over traditional breakwater structures. Results of empirical calculations and numerical modelling indicate that the MPR‟s will provide effective coastal protection through the processes of wave dissipation, wave rotation, salient formation and alteration of nearshore circulation. Physical modelling results allowed the MPR design to be assessed and refined in terms of surfing amenity enhancement and construction constraints. In addition numerical modelling results indicate that impacts due to the extraction of up to 600 000 m3 of sand from the lower Kromme Estuary result in highly localised velocity reduction, mainly limited to the extraction areas. The calculated rate of sediment influx into the lower Kromme Estuary indicates that limited extraction, in the order of 20 000 – 40 000 m3 per year, should be sustainable in the long term. Sedimentation of the lower estuary over recent years has had negative recreational and ecological impacts, through reduced navigability and water exchange respectively. Therefore both the estuary and beach systems prove to benefit from this approach. Although not investigated in detail as part of this study, evidence from numerous projects worldwide indicates that foredunes help to trap wind-blown sand on the beach and form a buffer to storm erosion, therefore dune rehabilitation with native sand-binding plant species was recommended as the third element of the proposed remediation of St Francis Bay beach.
- Full Text:
- Date Issued: 2008
The behaviour of the elements Ni, Co, Cu, Pb, Zn, Au, Ag, Mo, Sn, W and U in the magmatic, hydrothermal, sedimentary and weathering environments
- Authors: Anderson, J R
- Date: 1979
- Subjects: Elements , Environment , Ore deposits , Classification , Geochemistry , Crystal chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4896 , http://hdl.handle.net/10962/d1001555
- Description: In the last two decades much has been published on the behaviour of certain elements in the magmatic , hydrothermal, sedimentary and weathering environments , but the information is scattered throughout the literature . This situation prompted the present study on the elements Ni, Co, Cu, Pb , Zn , Au, Ag , Mo , Sn, W and U. The behaviour of the elements Ni, Cu, Pb , ZN, Au, Sn , W and U has been studied experimentally in some depth. Ag has been moderately studied, but there is very little information about Co and Mo. Studies on the complexes formed by the elements within the hydrothermal and aqueous environment are often inconclusive and controversial , but conclusions are drawn as to the more likely complexes formed . A genetic classification of ore deposits is used as a framework for the discussion . The source of the elements is regarded as being the mantle, and therefore discussion on other possible sources is beyond the scope of this dissertation. The crystal chemistry and geochemistry of the elements are presented and the essay concludes with a discussion on the elements within their depositional environments
- Full Text:
- Date Issued: 1979
- Authors: Anderson, J R
- Date: 1979
- Subjects: Elements , Environment , Ore deposits , Classification , Geochemistry , Crystal chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4896 , http://hdl.handle.net/10962/d1001555
- Description: In the last two decades much has been published on the behaviour of certain elements in the magmatic , hydrothermal, sedimentary and weathering environments , but the information is scattered throughout the literature . This situation prompted the present study on the elements Ni, Co, Cu, Pb , Zn , Au, Ag , Mo , Sn, W and U. The behaviour of the elements Ni, Cu, Pb , ZN, Au, Sn , W and U has been studied experimentally in some depth. Ag has been moderately studied, but there is very little information about Co and Mo. Studies on the complexes formed by the elements within the hydrothermal and aqueous environment are often inconclusive and controversial , but conclusions are drawn as to the more likely complexes formed . A genetic classification of ore deposits is used as a framework for the discussion . The source of the elements is regarded as being the mantle, and therefore discussion on other possible sources is beyond the scope of this dissertation. The crystal chemistry and geochemistry of the elements are presented and the essay concludes with a discussion on the elements within their depositional environments
- Full Text:
- Date Issued: 1979