An ergonomics intervention study into the physiological, perceptual and productivity effects of three citrus harvesting bag designs in the Eastern Cape of South Africa : a combined laboratory and field approach
- Bassey-Duke, Elizabeth Misan
- Authors: Bassey-Duke, Elizabeth Misan
- Date: 2015
- Subjects: Citrus -- Harvesting -- South Africa -- Eastern Cape , Lifting and carrying -- South Africa -- Eastern Cape , Manual work -- South Africa -- Eastern Cape , Blue collar workers -- South Africa -- Eastern Cape , Work -- Physiological aspects , Human mechanics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5176 , http://hdl.handle.net/10962/d1018908
- Description: Background: Agriculture plays a vital role in the economy of any industrially developing country, including South Africa. In the Eastern Cape of South Africa citrus farming is a significant contributor to the local economy (Johnson et al., 2005). The harvesting phase of citrus farming is performed manually and exposes workers to physical risks, which can lead to the development of musculoskeletal disorders. In particular, the standard harvesting bag comprises of a single shoulder strap and promotes asymmetrical load carriage which results in shoulder and lower back pain complaints. The current study compared the physiological (EMG), perceptual (RPE), usability (PUEU) and productivity effects of two new harvesting bag designs (a hip belt and a backpack bag design) to the standard harvesting bag design. This was performed in a laboratory as well as a field setting. Methods (Laboratory phase): 36 participants (12 males and 24 females) were assigned to one worker group. The “tall ladder worker” group was comprised of only males and the “step ladder worker” and “ground worker” group of females. Each participant was required to simulate a citrus harvesting task while utilizing each of the bag designs on different days. On each day/test session, participants performed three harvesting cycles. Muscle activity was measured throughout the entire testing session and RPE were recorded at the end of each cycle. Results (Laboratory phase): The EMG and RPE results indicate that the backpack design was the most ideal design to reduce asymmetry, while the standard harvesting bag design was the worst. Although not significant, there was greater muscle asymmetry (p=0.109) and a significantly higher perceived exertion when using the standard bag (p=0.0004), in comparison to using the backpack. Methods (Field phase): 17 Xhosa-speaking citrus harvesters (6 females and 11 males) participated in this study. Each harvester worked with one of the three bag designs on a different day. Productivity of each worker was assessed every hour by recording the number of bags filled with fruit and at the end of the shift. A Perceived Usefulness & Ease of Use questionnaire was presented to each participant to obtain feedback on worker acceptance to the new bag designs. Results (Field phase): A general trend in support of the hip belt bag design over the other two bag designs were found, even within the different worker demographic groups (age, sex and worker experience). The workers perceived less exertion (7.98 ± 1.86) and were more productive (9.90 ± 2.11 bags/hour) when using the hip belt design; they also found this bag the most useful (1.02 ± 0.09) and easy to use (1.07 ± 0.25). In contrast, the backpack bag design had significantly poorer responses when compared to the other two bag designs and this was evident in all the dependent variables assessed (RPE, productivity and PUEU). Conclusion: The results from the laboratory phase supported the expectation that the backpack bag design reduces asymmetry and hence, is more suitable than the standard harvesting bag. However, results from the field show that the hip belt bag design was the most preferred and the backpack was the least preferred. Bao & Shahnavaz (1989) highlight the need for ergonomics researcher to convey laboratory findings into the field context. However, as shown by the current study, there are numerous challenges associated with field work, making it difficult for laboratory findings to be successfully conveyed to the field. Limitations and Recommendations: For the laboratory phase of the project, no biomechanical and cardiovascular responses were assessed. However, for a holistic approach, these variables should be considered in future studies. Due to high variability from one harvesting cycle to another, more than three harvesting cycles should also be performed to accurately replicate the harvesting process as done in the field over extended durations of time. For the field phase, data should be collected from more than one citrus farm and thus a larger sample size could be obtained. This would improve the validity of the study. In addition to this, data should be collected for a full working day, especially if environmental conditions are not a hindrance, as well as for a whole season, since workloads vary, depending on the time of the harvesting season. , Name on Graduation Programme: Bassey-Duke, Elizabeth Missan
- Full Text:
- Authors: Bassey-Duke, Elizabeth Misan
- Date: 2015
- Subjects: Citrus -- Harvesting -- South Africa -- Eastern Cape , Lifting and carrying -- South Africa -- Eastern Cape , Manual work -- South Africa -- Eastern Cape , Blue collar workers -- South Africa -- Eastern Cape , Work -- Physiological aspects , Human mechanics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5176 , http://hdl.handle.net/10962/d1018908
- Description: Background: Agriculture plays a vital role in the economy of any industrially developing country, including South Africa. In the Eastern Cape of South Africa citrus farming is a significant contributor to the local economy (Johnson et al., 2005). The harvesting phase of citrus farming is performed manually and exposes workers to physical risks, which can lead to the development of musculoskeletal disorders. In particular, the standard harvesting bag comprises of a single shoulder strap and promotes asymmetrical load carriage which results in shoulder and lower back pain complaints. The current study compared the physiological (EMG), perceptual (RPE), usability (PUEU) and productivity effects of two new harvesting bag designs (a hip belt and a backpack bag design) to the standard harvesting bag design. This was performed in a laboratory as well as a field setting. Methods (Laboratory phase): 36 participants (12 males and 24 females) were assigned to one worker group. The “tall ladder worker” group was comprised of only males and the “step ladder worker” and “ground worker” group of females. Each participant was required to simulate a citrus harvesting task while utilizing each of the bag designs on different days. On each day/test session, participants performed three harvesting cycles. Muscle activity was measured throughout the entire testing session and RPE were recorded at the end of each cycle. Results (Laboratory phase): The EMG and RPE results indicate that the backpack design was the most ideal design to reduce asymmetry, while the standard harvesting bag design was the worst. Although not significant, there was greater muscle asymmetry (p=0.109) and a significantly higher perceived exertion when using the standard bag (p=0.0004), in comparison to using the backpack. Methods (Field phase): 17 Xhosa-speaking citrus harvesters (6 females and 11 males) participated in this study. Each harvester worked with one of the three bag designs on a different day. Productivity of each worker was assessed every hour by recording the number of bags filled with fruit and at the end of the shift. A Perceived Usefulness & Ease of Use questionnaire was presented to each participant to obtain feedback on worker acceptance to the new bag designs. Results (Field phase): A general trend in support of the hip belt bag design over the other two bag designs were found, even within the different worker demographic groups (age, sex and worker experience). The workers perceived less exertion (7.98 ± 1.86) and were more productive (9.90 ± 2.11 bags/hour) when using the hip belt design; they also found this bag the most useful (1.02 ± 0.09) and easy to use (1.07 ± 0.25). In contrast, the backpack bag design had significantly poorer responses when compared to the other two bag designs and this was evident in all the dependent variables assessed (RPE, productivity and PUEU). Conclusion: The results from the laboratory phase supported the expectation that the backpack bag design reduces asymmetry and hence, is more suitable than the standard harvesting bag. However, results from the field show that the hip belt bag design was the most preferred and the backpack was the least preferred. Bao & Shahnavaz (1989) highlight the need for ergonomics researcher to convey laboratory findings into the field context. However, as shown by the current study, there are numerous challenges associated with field work, making it difficult for laboratory findings to be successfully conveyed to the field. Limitations and Recommendations: For the laboratory phase of the project, no biomechanical and cardiovascular responses were assessed. However, for a holistic approach, these variables should be considered in future studies. Due to high variability from one harvesting cycle to another, more than three harvesting cycles should also be performed to accurately replicate the harvesting process as done in the field over extended durations of time. For the field phase, data should be collected from more than one citrus farm and thus a larger sample size could be obtained. This would improve the validity of the study. In addition to this, data should be collected for a full working day, especially if environmental conditions are not a hindrance, as well as for a whole season, since workloads vary, depending on the time of the harvesting season. , Name on Graduation Programme: Bassey-Duke, Elizabeth Missan
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Encouraging individual retirement savings in South Africa
- Authors: Hirschbeck, Lisa
- Date: 2015
- Subjects: Retirement income -- Planning-- South Africa , Retirement income -- Government policy -- South Africa , Pension trusts -- South Africa -- Management , Pension trusts -- Termination -- Law and legislation -- South Africa , Income tax deductions for retirement contributions -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:913 , http://hdl.handle.net/10962/d1017535
- Description: Many South Africans may not have adequate retirement savings when they retire and this has the effect of a low income replacement ratio on retirement that may lead to a decrease in the standard of living of the retiree and in extreme cases the retiree becoming dependent on their family and the government. Owing to this trend of no or inadequate retirement savings, South Africa embarked on a retirement reform journey in 2004. The goal of this research is to determine whether the retirement reform mechanisms outlined by National Treasury would encourage individual retirement savings that should assist South Africans to achieve stability of income in their retirement. This research analysed the current retirement savings options and vehicles available for South Africans, the current tax incentives and disincentives and reviewed the proposed changes to tax incentives and disincentives during the accumulation phase of retirement savings and explained how these proposed tax incentives are harmonised for the accumulation phase of retirement. The research explained how National Treasury aims to limit pre-retirement withdrawals and how it intends to encourage the annuitisation of post-retirement benefits. The penultimate chapter of this research measured the effect (by making certain assumptions) of the changes proposed by National Treasury on the income replacement ratio of the retiree. Throughout the research comparisons were made between The OECD Roadmap for the good design of defined contribution pension plans and National Treasury’s proposals. This research did not directly address the effect of increased life expectancies on retirement savings or increases in youth unemployment and the effect that this may have on retirement savings. The effect of financial charges levied on retirement savings on the income replacement ratio of a retiree was also not explored. Furthermore, not all pension funds are regulated by the Pension Funds Act and how these pension funds can be brought within the purview of the Pension Funds Act was not investigated. Automatic enrolment of retirement savings for all employees in South Africa in retirement vehicles is a further research area that could be addressed.
- Full Text:
- Authors: Hirschbeck, Lisa
- Date: 2015
- Subjects: Retirement income -- Planning-- South Africa , Retirement income -- Government policy -- South Africa , Pension trusts -- South Africa -- Management , Pension trusts -- Termination -- Law and legislation -- South Africa , Income tax deductions for retirement contributions -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:913 , http://hdl.handle.net/10962/d1017535
- Description: Many South Africans may not have adequate retirement savings when they retire and this has the effect of a low income replacement ratio on retirement that may lead to a decrease in the standard of living of the retiree and in extreme cases the retiree becoming dependent on their family and the government. Owing to this trend of no or inadequate retirement savings, South Africa embarked on a retirement reform journey in 2004. The goal of this research is to determine whether the retirement reform mechanisms outlined by National Treasury would encourage individual retirement savings that should assist South Africans to achieve stability of income in their retirement. This research analysed the current retirement savings options and vehicles available for South Africans, the current tax incentives and disincentives and reviewed the proposed changes to tax incentives and disincentives during the accumulation phase of retirement savings and explained how these proposed tax incentives are harmonised for the accumulation phase of retirement. The research explained how National Treasury aims to limit pre-retirement withdrawals and how it intends to encourage the annuitisation of post-retirement benefits. The penultimate chapter of this research measured the effect (by making certain assumptions) of the changes proposed by National Treasury on the income replacement ratio of the retiree. Throughout the research comparisons were made between The OECD Roadmap for the good design of defined contribution pension plans and National Treasury’s proposals. This research did not directly address the effect of increased life expectancies on retirement savings or increases in youth unemployment and the effect that this may have on retirement savings. The effect of financial charges levied on retirement savings on the income replacement ratio of a retiree was also not explored. Furthermore, not all pension funds are regulated by the Pension Funds Act and how these pension funds can be brought within the purview of the Pension Funds Act was not investigated. Automatic enrolment of retirement savings for all employees in South Africa in retirement vehicles is a further research area that could be addressed.
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Staged authenticities an exploration of the representations of AmaXhosa culture within the main programme of the National Arts Festival, 2009
- Reeve, Zoë Rose Louise Patricia
- Authors: Reeve, Zoë Rose Louise Patricia
- Date: 2011
- Subjects: Standard Bank National Arts Festival Performing arts festivals -- South Africa -- Grahamstown Xhosa (African people) -- Music -- Social aspects Performing arts festivals -- Social aspects -- South Africa -- Grahamstown Cultural property -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2146 , http://hdl.handle.net/10962/d1002378
- Description: This thesis investigates the presentation of AmaXhosa traditional dancing and music on the stages of the National Arts Festival (NAF), Main Programme, of South Africa in 2009. Four productions featuring AmaXhosa traditional dancing and music, as well as a fine art exhibition, are analysed to determine how the AmaXhosa culture is being portrayed, what is considered authentic and how these productions may affect the memory of the AmaXhosa nation. In an attempt to understand the position of these productions within the NAF the South African cultural context as well as the NAF is examined. The post-apartheid, post-rainbow nation, South African cultural context is discussed and how the NAF could contribute towards creating a more unified South African identity. Incorporated and inscribed memory categories are related to how one could determine authenticity in traditional indigenous productions. A cautionary note on incorporated memory is linked to efficacy, while a loss of incorporated memory within the AmaXhosa society may result in ritual acts being orientated towards entertainment. If the private culture is consistently displayed in the public realm then it is inevitable that the ways in which the AmaXhosa recollect their history will be altered. The contribution of the transitional spaces of theatres and proscenium arch stages to the choreography and incorporated memory of the performers relates to the collective recollection of the AmaXhosa. Bearing this in mind, this thesis suggests that the NAF is playing a dual role in the evolution of the AmaXhosa. It is both positively contributing to the economic upliftment of a sector of the population and exposing people to this rich and multilayered culture. However, it is also impacting the efficacy of the private culture and fracturing the traditional knowledge of the AmaXhosa by assisting in the inscription of their performance forms. , This thesis consists of three parts (1 pdf document and two video mp4 files)
- Full Text:
- Authors: Reeve, Zoë Rose Louise Patricia
- Date: 2011
- Subjects: Standard Bank National Arts Festival Performing arts festivals -- South Africa -- Grahamstown Xhosa (African people) -- Music -- Social aspects Performing arts festivals -- Social aspects -- South Africa -- Grahamstown Cultural property -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2146 , http://hdl.handle.net/10962/d1002378
- Description: This thesis investigates the presentation of AmaXhosa traditional dancing and music on the stages of the National Arts Festival (NAF), Main Programme, of South Africa in 2009. Four productions featuring AmaXhosa traditional dancing and music, as well as a fine art exhibition, are analysed to determine how the AmaXhosa culture is being portrayed, what is considered authentic and how these productions may affect the memory of the AmaXhosa nation. In an attempt to understand the position of these productions within the NAF the South African cultural context as well as the NAF is examined. The post-apartheid, post-rainbow nation, South African cultural context is discussed and how the NAF could contribute towards creating a more unified South African identity. Incorporated and inscribed memory categories are related to how one could determine authenticity in traditional indigenous productions. A cautionary note on incorporated memory is linked to efficacy, while a loss of incorporated memory within the AmaXhosa society may result in ritual acts being orientated towards entertainment. If the private culture is consistently displayed in the public realm then it is inevitable that the ways in which the AmaXhosa recollect their history will be altered. The contribution of the transitional spaces of theatres and proscenium arch stages to the choreography and incorporated memory of the performers relates to the collective recollection of the AmaXhosa. Bearing this in mind, this thesis suggests that the NAF is playing a dual role in the evolution of the AmaXhosa. It is both positively contributing to the economic upliftment of a sector of the population and exposing people to this rich and multilayered culture. However, it is also impacting the efficacy of the private culture and fracturing the traditional knowledge of the AmaXhosa by assisting in the inscription of their performance forms. , This thesis consists of three parts (1 pdf document and two video mp4 files)
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Stewardship as an educational process of social learning and change: two case studies conducted in the Western Cape
- Authors: Walker, Clara Isabella
- Date: 2011
- Subjects: Environmental education -- South Africa -- Western Cape Conservation of natural resources -- South Africa -- Western Cape Natural resources -- South Africa -- Western Cape -- Management Social learning -- South Africa -- Western Cape Sustainable development -- South Africa -- Western Cape Cape Nature Stewardship Programme (South Africa) Biodiversity Stewardship Programme (South Africa)
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1772 , http://hdl.handle.net/10962/d1003657
- Description: Stewardship in South Africa, as it is being implemented within the framework of the Biodiversity Stewardship Programme (BSP), is an attempt by conservation agencies to engage landowners in the voluntary securing of parcels of biodiverse land, through signing a contract for a certain time period, not to develop the landscape in ways that will impact negatively on the biodiversity of the area in question. The focus of this study is the relationship between biodiversity stewardship and social learning, as I hope to ascertain how stewardship practices are helping to resolve the current problems of biodiversity loss in the Western Cape. The overall aim of this research is to gain an understanding of how, in its capacity as a conservation education process, the Cape Nature Stewardship Programme can foster social learning amongst the landowners involved in its implementation, by leading them to a better understanding of their environmental responsibilities. Data was generated through the use of interviews and informal discussions with participants together with document analysis, such as brochures, pamphlets and presentations. My approach to the analysis of my data was two-phased. In the first phase, I analysed the data generated from the interview process and from reviewing the documents the stewardship officials supplied me with. The second phase involved looking into the results of the two case studies, and formulating analytical statements which were then used to review the case evidence within a social learning perspective, derived from Wals (2007). In constructing an analytical framework for the interpretation of my data, I drew heavily on Wals' (2007) notion of social learning occurring in sequential activities. I used this insight as a lens through which to trace the educational effects of the implementation of the CNSP in the two case study areas.The research highlighted evidence that Stewardship initiatives should be based on the foundation of social learning and invest time and effort in building an environmental knowledge capital amongst the landowners involved. By equipping them with these necessary conservation skills, one creates a 'community of practice' where those individuals adopt a sustainability habitus contributing towards a change and environmental understanding and practises in field.
- Full Text:
- Authors: Walker, Clara Isabella
- Date: 2011
- Subjects: Environmental education -- South Africa -- Western Cape Conservation of natural resources -- South Africa -- Western Cape Natural resources -- South Africa -- Western Cape -- Management Social learning -- South Africa -- Western Cape Sustainable development -- South Africa -- Western Cape Cape Nature Stewardship Programme (South Africa) Biodiversity Stewardship Programme (South Africa)
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1772 , http://hdl.handle.net/10962/d1003657
- Description: Stewardship in South Africa, as it is being implemented within the framework of the Biodiversity Stewardship Programme (BSP), is an attempt by conservation agencies to engage landowners in the voluntary securing of parcels of biodiverse land, through signing a contract for a certain time period, not to develop the landscape in ways that will impact negatively on the biodiversity of the area in question. The focus of this study is the relationship between biodiversity stewardship and social learning, as I hope to ascertain how stewardship practices are helping to resolve the current problems of biodiversity loss in the Western Cape. The overall aim of this research is to gain an understanding of how, in its capacity as a conservation education process, the Cape Nature Stewardship Programme can foster social learning amongst the landowners involved in its implementation, by leading them to a better understanding of their environmental responsibilities. Data was generated through the use of interviews and informal discussions with participants together with document analysis, such as brochures, pamphlets and presentations. My approach to the analysis of my data was two-phased. In the first phase, I analysed the data generated from the interview process and from reviewing the documents the stewardship officials supplied me with. The second phase involved looking into the results of the two case studies, and formulating analytical statements which were then used to review the case evidence within a social learning perspective, derived from Wals (2007). In constructing an analytical framework for the interpretation of my data, I drew heavily on Wals' (2007) notion of social learning occurring in sequential activities. I used this insight as a lens through which to trace the educational effects of the implementation of the CNSP in the two case study areas.The research highlighted evidence that Stewardship initiatives should be based on the foundation of social learning and invest time and effort in building an environmental knowledge capital amongst the landowners involved. By equipping them with these necessary conservation skills, one creates a 'community of practice' where those individuals adopt a sustainability habitus contributing towards a change and environmental understanding and practises in field.
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Intertidal patterns and processes : tracking the effects of coastline topography and settlement choice across life stages of the mussels perna perna and mytilus galloprovincialis
- Von der Meden, Charles Eric Otto
- Authors: Von der Meden, Charles Eric Otto
- Date: 2010
- Subjects: Mexilhao mussel -- Behavior -- South Africa Mytilus galloprovincialis -- Behavior -- South Africa Perna -- Behavior -- South Africa Mussels -- Ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5721 , http://hdl.handle.net/10962/d1005407
- Description: Within landscapes, spatial heterogeneity is common and specific landscape features can influence propagule dispersal by wind or water, affecting population connectivity and dynamics. Coastline topographic features, such as bays and headlands, have a variety of biophysical effects on nearshore oceanography, larval transport, retention and supply, and the processes of larval settlement and recruitment. Although this has been demonstrated in several parts of the world, engendering a perception of a general ‘bay effect’, few studies have investigated this generality in a single experiment or region, by replicating at the level of ‘bay’. The Agulhas biogeographic region of the south coast of South Africa is a useful system within which to test for such generality. Using the intertidal mussels Mytilus galloprovincialis and Perna perna as model organisms, patterns of adult distribution were surveyed across four large ‘halfheart’ bays and intervening stretches of open coast, providing replication at the level of ‘bay’ and duplication of ecologically similar species. In support of a general, pervasive influence of bays on intertidal populations, mussel cover was found to be greater in bays than on the open coast for both species, although the effect was strongest for M. galloprovincialis. To explain this adult distribution, settlement, post-settlement mortality and recruitment were examined over 12mo at the same sites, with the prediction that rates of each would favour larger bay populations. Contrary to this, an interaction between month and bay-status was found, with greater settlement and recruitment on the open coast than in bays reflecting extreme settlement and recruitment events at 3 westerly open coast sites during summer. Re-analysis excluding these outliers, revealed the expected effect, of greater settlement and recruitment in bays. While this indicates the broad generality of the bay effect, it highlights exceptions and the need for replication in time and space when examining landscape effects. Measuring post-settlement mortality required testing small-scale settlement behaviour on established and newly deployed settler collectors. It was found that all settlers preferred collectors with biofilm, but that primary settlers avoided conspecific settlers, while secondary settlers were attracted to them. With discrepancies in settler attraction to new and established collectors accounted for, initial (over 2d) and longer-term (over 7d) post-settlement mortality rates were found to be substantial (ca 60 %) for both species. No topographic effect on p-s mortality was evident. Finally, recruit-settler, adult-recruit and interspecies correlations were examined at regional and local scales. Synergistic (or neutral) effects maintained the initial settlement pattern in recruit and adult populations regionally, but not at local scales; striking interspecies correlations suggested the influence of common regional transport processes. Ultimately, the results emphasize the importance of the direction of effects in different life stages and at different spatial scales, and the possibility that antagonistic effects may mask even strong patterns.
- Full Text:
- Authors: Von der Meden, Charles Eric Otto
- Date: 2010
- Subjects: Mexilhao mussel -- Behavior -- South Africa Mytilus galloprovincialis -- Behavior -- South Africa Perna -- Behavior -- South Africa Mussels -- Ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5721 , http://hdl.handle.net/10962/d1005407
- Description: Within landscapes, spatial heterogeneity is common and specific landscape features can influence propagule dispersal by wind or water, affecting population connectivity and dynamics. Coastline topographic features, such as bays and headlands, have a variety of biophysical effects on nearshore oceanography, larval transport, retention and supply, and the processes of larval settlement and recruitment. Although this has been demonstrated in several parts of the world, engendering a perception of a general ‘bay effect’, few studies have investigated this generality in a single experiment or region, by replicating at the level of ‘bay’. The Agulhas biogeographic region of the south coast of South Africa is a useful system within which to test for such generality. Using the intertidal mussels Mytilus galloprovincialis and Perna perna as model organisms, patterns of adult distribution were surveyed across four large ‘halfheart’ bays and intervening stretches of open coast, providing replication at the level of ‘bay’ and duplication of ecologically similar species. In support of a general, pervasive influence of bays on intertidal populations, mussel cover was found to be greater in bays than on the open coast for both species, although the effect was strongest for M. galloprovincialis. To explain this adult distribution, settlement, post-settlement mortality and recruitment were examined over 12mo at the same sites, with the prediction that rates of each would favour larger bay populations. Contrary to this, an interaction between month and bay-status was found, with greater settlement and recruitment on the open coast than in bays reflecting extreme settlement and recruitment events at 3 westerly open coast sites during summer. Re-analysis excluding these outliers, revealed the expected effect, of greater settlement and recruitment in bays. While this indicates the broad generality of the bay effect, it highlights exceptions and the need for replication in time and space when examining landscape effects. Measuring post-settlement mortality required testing small-scale settlement behaviour on established and newly deployed settler collectors. It was found that all settlers preferred collectors with biofilm, but that primary settlers avoided conspecific settlers, while secondary settlers were attracted to them. With discrepancies in settler attraction to new and established collectors accounted for, initial (over 2d) and longer-term (over 7d) post-settlement mortality rates were found to be substantial (ca 60 %) for both species. No topographic effect on p-s mortality was evident. Finally, recruit-settler, adult-recruit and interspecies correlations were examined at regional and local scales. Synergistic (or neutral) effects maintained the initial settlement pattern in recruit and adult populations regionally, but not at local scales; striking interspecies correlations suggested the influence of common regional transport processes. Ultimately, the results emphasize the importance of the direction of effects in different life stages and at different spatial scales, and the possibility that antagonistic effects may mask even strong patterns.
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Incorporating indigenous knowledge in the teaching of isiXhosa to pharmacy students at Rhodes University
- Authors: Mapi, Thandeka Priscilla
- Date: 2009
- Subjects: Rhodes University. Academic Development Programme Healers -- South Africa Traditional medicine -- South Africa Xhosa language -- Study and teaching -- South Africa Pharmacy -- Study and teaching -- South Africa Ethnoscience -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3622 , http://hdl.handle.net/10962/d1007469
- Description: Traditional healing is one of the most trusted methods of healing in South Africa, especially in rural areas, where health-care infrastructure is inadequate. People have depended on this method of healing since time immemorial. That belief has been strengthened by the fact that this method keeps people in touch with their ancestors. Traditional healers are trusted and believed to be the link between people and their ancestors. The Dwesa community is amongst the areas that still have strong belief in traditional healing. Traditional healers have a variety of methods of healing that they use, these methods have been trusted for people of all age groups. These methods are ukugabha, ukufutha and ukucima. Traditional healers prescribe them for both major and minor illnesses. They are believed to play a role in cleansing people from inside and outside. These methods together with other methods that are used in traditional healing are being explored in this study. This exploration is based on the fact that this information will be integrated into the teaching of isiXhosa to Pharmacy students at Rhodes University. This is an initiative to create awareness amongst health-care practitioners about traditional healing methods, so that they can caution and advise their patients about medicine taking behaviours, also to make them approach the subject in a sensitive manner. An isiXhosa course has been taught to Pharmacy students, as a pilot in 2007 and as an elective in 2008 onwards. This course deals with cultural issues in a broad manner, the issue of traditional healing specifically, and these methods of healing are outlined in the course, such that students have an understanding first of what a traditional healer is and their role in providing health-care services.
- Full Text:
- Authors: Mapi, Thandeka Priscilla
- Date: 2009
- Subjects: Rhodes University. Academic Development Programme Healers -- South Africa Traditional medicine -- South Africa Xhosa language -- Study and teaching -- South Africa Pharmacy -- Study and teaching -- South Africa Ethnoscience -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3622 , http://hdl.handle.net/10962/d1007469
- Description: Traditional healing is one of the most trusted methods of healing in South Africa, especially in rural areas, where health-care infrastructure is inadequate. People have depended on this method of healing since time immemorial. That belief has been strengthened by the fact that this method keeps people in touch with their ancestors. Traditional healers are trusted and believed to be the link between people and their ancestors. The Dwesa community is amongst the areas that still have strong belief in traditional healing. Traditional healers have a variety of methods of healing that they use, these methods have been trusted for people of all age groups. These methods are ukugabha, ukufutha and ukucima. Traditional healers prescribe them for both major and minor illnesses. They are believed to play a role in cleansing people from inside and outside. These methods together with other methods that are used in traditional healing are being explored in this study. This exploration is based on the fact that this information will be integrated into the teaching of isiXhosa to Pharmacy students at Rhodes University. This is an initiative to create awareness amongst health-care practitioners about traditional healing methods, so that they can caution and advise their patients about medicine taking behaviours, also to make them approach the subject in a sensitive manner. An isiXhosa course has been taught to Pharmacy students, as a pilot in 2007 and as an elective in 2008 onwards. This course deals with cultural issues in a broad manner, the issue of traditional healing specifically, and these methods of healing are outlined in the course, such that students have an understanding first of what a traditional healer is and their role in providing health-care services.
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Studies of equivalent fuzzy subgroups of finite abelian p-Groups of rank two and their subgroup lattices
- Authors: Ngcibi, Sakhile Leonard
- Date: 2006
- Subjects: Abelian groups Fuzzy sets Finite groups Group theory Polynomials
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5416 , http://hdl.handle.net/10962/d1005230
- Description: We determine the number and nature of distinct equivalence classes of fuzzy subgroups of finite Abelian p-group G of rank two under a natural equivalence relation on fuzzy subgroups. Our discussions embrace the necessary theory from groups with special emphasis on finite p-groups as a step towards the classification of crisp subgroups as well as maximal chains of subgroups. Unique naming of subgroup generators as discussed in this work facilitates counting of subgroups and chains of subgroups from subgroup lattices of the groups. We cover aspects of fuzzy theory including fuzzy (homo-) isomorphism together with operations on fuzzy subgroups. The equivalence characterization as discussed here is finer than isomorphism. We introduce the theory of keychains with a view towards the enumeration of maximal chains as well as fuzzy subgroups under the equivalence relation mentioned above. We discuss a strategy to develop subgroup lattices of the groups used in the discussion, and give examples for specific cases of prime p and positive integers n,m. We derive formulas for both the number of maximal chains as well as the number of distinct equivalence classes of fuzzy subgroups. The results are in the form of polynomials in p (known in the literature as Hall polynomials) with combinatorial coefficients. Finally we give a brief investigation of the results from a graph-theoretic point of view. We view the subgroup lattices of these groups as simple, connected, symmetric graphs.
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- Authors: Ngcibi, Sakhile Leonard
- Date: 2006
- Subjects: Abelian groups Fuzzy sets Finite groups Group theory Polynomials
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5416 , http://hdl.handle.net/10962/d1005230
- Description: We determine the number and nature of distinct equivalence classes of fuzzy subgroups of finite Abelian p-group G of rank two under a natural equivalence relation on fuzzy subgroups. Our discussions embrace the necessary theory from groups with special emphasis on finite p-groups as a step towards the classification of crisp subgroups as well as maximal chains of subgroups. Unique naming of subgroup generators as discussed in this work facilitates counting of subgroups and chains of subgroups from subgroup lattices of the groups. We cover aspects of fuzzy theory including fuzzy (homo-) isomorphism together with operations on fuzzy subgroups. The equivalence characterization as discussed here is finer than isomorphism. We introduce the theory of keychains with a view towards the enumeration of maximal chains as well as fuzzy subgroups under the equivalence relation mentioned above. We discuss a strategy to develop subgroup lattices of the groups used in the discussion, and give examples for specific cases of prime p and positive integers n,m. We derive formulas for both the number of maximal chains as well as the number of distinct equivalence classes of fuzzy subgroups. The results are in the form of polynomials in p (known in the literature as Hall polynomials) with combinatorial coefficients. Finally we give a brief investigation of the results from a graph-theoretic point of view. We view the subgroup lattices of these groups as simple, connected, symmetric graphs.
- Full Text:
The degradation of lignocellulose in a biologically-generated sulphidic environment
- Authors: Roman, Henry James
- Date: 2005
- Subjects: Lignocellulose Sulfides Lignin Lignocellulose -- Biodegradation Mines and mineral resources -- Waste disposal Acid mine drainage
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3997 , http://hdl.handle.net/10962/d1004057
- Description: South Africa is renowned for its mining industry. The period over which the polluted waters from the existing and abandoned mines will require treatment has driven research into the development of passive treatment systems. These waters are characterised by a low pH, high concentrations of heavy metals, high levels of sulphate salts and low concentrations of organic material. The biological treatment of these waters has been a subject of increasing focus as an alternative to physicochemical treatment. The utilisation of lignocellulose as a carbon source has been restricted by the amount of reducing equivalents available within the lignocellulose matrix. After a few months of near 100% sulphate reduction, it was found that although there was a large fraction of lignin and cellulose remaining, sulphate reduction was reduced to less than 20%. The present study demonstrated that lignocellulose can be utilised as a carbon source for sulphate reduction. It was established that lignocellulose degradation was enhanced under biosulphidogenic conditions and that lignin could be degraded by a sulphate reducing microbial consortium. It was established using lignin model compounds synthesized in our laboratory, that the bonds within the lignin polymer can be cleaved within the sulphidic environment. The presence of cellulolytic enzymes, using CMCase as a marker enzyme, was detected within the sulphate reducing microbial consortium. Based on the results obtained a descriptive model was formulated for the degradation of lignocellulose under biosulphidogenic conditions. It was determined that the initial reduction in sulphate observed using lignocellulose as a carbon source was due to the easily extractable components. The degradation of which resulted in the production of sulphide, which aided in the degradation of lignin, allowing greater access to cellulose. Once the easily extractable material is exhausted, the cycle is halted, unless the sulphide production can be maintained. This is the focus of an ongoing project, testing the hypothesis that an easy to assimilate carbon source added after exhaustion of the easily extractable material, can maintain the sulphide production.
- Full Text:
- Authors: Roman, Henry James
- Date: 2005
- Subjects: Lignocellulose Sulfides Lignin Lignocellulose -- Biodegradation Mines and mineral resources -- Waste disposal Acid mine drainage
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3997 , http://hdl.handle.net/10962/d1004057
- Description: South Africa is renowned for its mining industry. The period over which the polluted waters from the existing and abandoned mines will require treatment has driven research into the development of passive treatment systems. These waters are characterised by a low pH, high concentrations of heavy metals, high levels of sulphate salts and low concentrations of organic material. The biological treatment of these waters has been a subject of increasing focus as an alternative to physicochemical treatment. The utilisation of lignocellulose as a carbon source has been restricted by the amount of reducing equivalents available within the lignocellulose matrix. After a few months of near 100% sulphate reduction, it was found that although there was a large fraction of lignin and cellulose remaining, sulphate reduction was reduced to less than 20%. The present study demonstrated that lignocellulose can be utilised as a carbon source for sulphate reduction. It was established that lignocellulose degradation was enhanced under biosulphidogenic conditions and that lignin could be degraded by a sulphate reducing microbial consortium. It was established using lignin model compounds synthesized in our laboratory, that the bonds within the lignin polymer can be cleaved within the sulphidic environment. The presence of cellulolytic enzymes, using CMCase as a marker enzyme, was detected within the sulphate reducing microbial consortium. Based on the results obtained a descriptive model was formulated for the degradation of lignocellulose under biosulphidogenic conditions. It was determined that the initial reduction in sulphate observed using lignocellulose as a carbon source was due to the easily extractable components. The degradation of which resulted in the production of sulphide, which aided in the degradation of lignin, allowing greater access to cellulose. Once the easily extractable material is exhausted, the cycle is halted, unless the sulphide production can be maintained. This is the focus of an ongoing project, testing the hypothesis that an easy to assimilate carbon source added after exhaustion of the easily extractable material, can maintain the sulphide production.
- Full Text:
A critical evaluation of outcomes based education from a developmental perspective in South Africa with particular reference to the Eastern Cape.
- Mdikane, Knowledge Mzwandile
- Authors: Mdikane, Knowledge Mzwandile
- Date: 2004
- Subjects: Reconstruction and Development Programme (South Africa) Competency-based education -- South Africa -- Eastern Cape Educational change -- South Africa -- Eastern Cape Education -- Social aspects -- South Africa -- Eastern Cape Curriculum change -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:6057 , http://hdl.handle.net/10962/d1006663
- Description: This research study seeks to examine the impact of Outcomes-Based Education (OBE)from a developmental perspective in the Eastern Cape. Two schools were selected as research sites, one from a previously advantaged area and the other from a previously disadvantaged area. These schools were evaluated on their understanding of OBE and its relationship to development. OBE was introduced in South Africa under controversial circumstances because of the legacy of apartheid education from which we are coming. Because of that, schools in South Africa reflect the inequalities that are resulting from apartheid legislation. In 1994 the government introduced the Reconstruction and Development Programme (RDP) to eradicate all the discrepancies resulting from apartheid. On the educational sphere, OBE was the curriculum policy aimed at eradicating the legacy of apartheid education. The then Minister of Education was convinced that OBE or Curriculum 2005 would be a developmental approach to education and would take South Africa into the 21st century. Ever since its introduction, educators have encountered many problems with the implementation of OBE, especially in the previously disadvantaged areas of the Eastern Cape. The researcher used semi-structured interviews to collect data from the respondents. However, one set of questionnaires was prepared for the educators, students, parents and education government officials. Because of the qualitative nature of the questionnaire the data collected was also analyzed qualitatively. Each question was analyzed from each of the focus groups and the researcher established findings that were analyzed in relation to the literature review. The researcher then was able to reach his own conclusions on the impact that OBE has on the South African education system and recommendations on what could be done for OBE to be successfully implemented and to be developmentally effective in previously disadvantaged areas of South Africa. The recommendations propose useful interventions, which could be made by the government to assist all the stakeholders involved in education in both an understanding and better implementation of OBE in Previously Disadvantaged Areas (PDA’s). They include provision of support to stakeholders and that teachers should be taught about the relationship between OBE and reconstruction. The research study focuses mainly on OBE and its relationship to development in urban or Previously Advantaged Areas (PAA’s) of two Eastern Cape schools. It will be relevant to the Eastern Cape Education Department in its efforts to implement OBE in schools and it could be a source of knowledge to educators. The conclusion that has been reached, however, is that there is a lot of ignorance about this new system of education to both educators and parents. There is also evidence of ignorance to matters pertaining to the relationship between OBE and it’s relationship to the Reconstruction and Development Programme (RDP). A major recommendation that is made then is that for OBE to be relevant in the South African context, it should help to improve the lives of ordinary people in South Africa, especially in Previously Disadvantaged Areas.
- Full Text:
- Authors: Mdikane, Knowledge Mzwandile
- Date: 2004
- Subjects: Reconstruction and Development Programme (South Africa) Competency-based education -- South Africa -- Eastern Cape Educational change -- South Africa -- Eastern Cape Education -- Social aspects -- South Africa -- Eastern Cape Curriculum change -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:6057 , http://hdl.handle.net/10962/d1006663
- Description: This research study seeks to examine the impact of Outcomes-Based Education (OBE)from a developmental perspective in the Eastern Cape. Two schools were selected as research sites, one from a previously advantaged area and the other from a previously disadvantaged area. These schools were evaluated on their understanding of OBE and its relationship to development. OBE was introduced in South Africa under controversial circumstances because of the legacy of apartheid education from which we are coming. Because of that, schools in South Africa reflect the inequalities that are resulting from apartheid legislation. In 1994 the government introduced the Reconstruction and Development Programme (RDP) to eradicate all the discrepancies resulting from apartheid. On the educational sphere, OBE was the curriculum policy aimed at eradicating the legacy of apartheid education. The then Minister of Education was convinced that OBE or Curriculum 2005 would be a developmental approach to education and would take South Africa into the 21st century. Ever since its introduction, educators have encountered many problems with the implementation of OBE, especially in the previously disadvantaged areas of the Eastern Cape. The researcher used semi-structured interviews to collect data from the respondents. However, one set of questionnaires was prepared for the educators, students, parents and education government officials. Because of the qualitative nature of the questionnaire the data collected was also analyzed qualitatively. Each question was analyzed from each of the focus groups and the researcher established findings that were analyzed in relation to the literature review. The researcher then was able to reach his own conclusions on the impact that OBE has on the South African education system and recommendations on what could be done for OBE to be successfully implemented and to be developmentally effective in previously disadvantaged areas of South Africa. The recommendations propose useful interventions, which could be made by the government to assist all the stakeholders involved in education in both an understanding and better implementation of OBE in Previously Disadvantaged Areas (PDA’s). They include provision of support to stakeholders and that teachers should be taught about the relationship between OBE and reconstruction. The research study focuses mainly on OBE and its relationship to development in urban or Previously Advantaged Areas (PAA’s) of two Eastern Cape schools. It will be relevant to the Eastern Cape Education Department in its efforts to implement OBE in schools and it could be a source of knowledge to educators. The conclusion that has been reached, however, is that there is a lot of ignorance about this new system of education to both educators and parents. There is also evidence of ignorance to matters pertaining to the relationship between OBE and it’s relationship to the Reconstruction and Development Programme (RDP). A major recommendation that is made then is that for OBE to be relevant in the South African context, it should help to improve the lives of ordinary people in South Africa, especially in Previously Disadvantaged Areas.
- Full Text:
Towards the development of species-specific fish production models for small reservoirs in Southern Africa
- Authors: Potts, Warren M
- Date: 2004
- Subjects: Freshwater fishes -- Africa, Southern Fish populations -- Africa, Southern Fisheries -- Africa, Southern Sustainable fisheries -- Africa, Southern Labeo -- Reproduction Cyprinidae -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5330 , http://hdl.handle.net/10962/d1005176
- Description: The fish populations in small southern African reservoirs are largely unexploited and there is potential for fisheries development. However, the development of sustainable fisheries requires reliable estimates of potential yield or production. Empirical models that have been developed to predict fish production only apply to large water bodies and only predict total fish production, not the production of individual species. Small reservoirs generally have few commercially important species and therefore species-specific fish production models are an alternative approach. The small reservoirs of the Eastern Cape are dominated by the moggel (Labeo umbratus). The principal objectives of this thesis were to gain an understanding of the ecology of small reservoirs and the function of moggel in these systems. This information was used to design a research approach to rapidly develop species-specific models for small reservoirs in southern Africa. The limnology of two small reservoirs was compared. During the study period the reservoirs were turbid and showed a warm, monomictic pattern of thermal stratification. Anthropogenic pressure in the reservoir catchments appeared to be the overriding factor increasing the nutrient input to the reservoirs and consequently, influencing the biomass of algae in the reservoirs. The feeding biology of moggel in Katriver and Laing reservoirs was examined. Moggel are detrivorous and successfully digested diatoms. The slower growth rate of moggel in Katriver reservoir was attributed to the poorer nutritional value of the diet as a consequence of the lower concentration of diatoms in the detrital aggregate. The reproductive characteristics of moggel were examined in four reservoirs. Moggel were able to reproduce successfully in the reservoirs. This could be attributed to their r-selected reproductive strategy, with a high fecundity and an extended spawning season and their ability to spawn in a floodplain environment. Differences in recruitment success between years were found to be a consequence of the timing and duration of seasonal rains. The number of mature females in a population and the availability of suitable spawning habitat influenced recruitment success. The life history of the moggel in five reservoirs was compared. Growth appeared to be related to food availability, while mortality was lower in the populations where food was abundant and there were less predatory species. Size and age at maturity were not affected by environmental factors, but were dependent on growth and mortality. Three contrasting methods were used to estimate moggel gillnet selectivity. The Sechin, direct fyke net method and length-structured model all yielded similar results and correction factors obtained from the selectivity study were applied to the gillnet data to estimate the fish population size and structure in each reservoir. Using information from the life history and selectivity studies, the biomass and production of five moggel populations was estimated and related to abiotic and biotic factors in the reservoirs and their catchments. Moggel biomass and production was dependent on the biomass of algae, which was dependent on morphoedaphic characteristics of the reservoirs. Small, shallow reservoirs with a reasonable amount of human habitation in their catchments would sustain the highest algal biomass and provided they had adequate spawning habitat would also have the highest moggel biomass and production. The future research requirements for small reservoir fisheries are outlined and include a three-year program to develop a species-specific production model for any of the dominant species.
- Full Text:
- Authors: Potts, Warren M
- Date: 2004
- Subjects: Freshwater fishes -- Africa, Southern Fish populations -- Africa, Southern Fisheries -- Africa, Southern Sustainable fisheries -- Africa, Southern Labeo -- Reproduction Cyprinidae -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5330 , http://hdl.handle.net/10962/d1005176
- Description: The fish populations in small southern African reservoirs are largely unexploited and there is potential for fisheries development. However, the development of sustainable fisheries requires reliable estimates of potential yield or production. Empirical models that have been developed to predict fish production only apply to large water bodies and only predict total fish production, not the production of individual species. Small reservoirs generally have few commercially important species and therefore species-specific fish production models are an alternative approach. The small reservoirs of the Eastern Cape are dominated by the moggel (Labeo umbratus). The principal objectives of this thesis were to gain an understanding of the ecology of small reservoirs and the function of moggel in these systems. This information was used to design a research approach to rapidly develop species-specific models for small reservoirs in southern Africa. The limnology of two small reservoirs was compared. During the study period the reservoirs were turbid and showed a warm, monomictic pattern of thermal stratification. Anthropogenic pressure in the reservoir catchments appeared to be the overriding factor increasing the nutrient input to the reservoirs and consequently, influencing the biomass of algae in the reservoirs. The feeding biology of moggel in Katriver and Laing reservoirs was examined. Moggel are detrivorous and successfully digested diatoms. The slower growth rate of moggel in Katriver reservoir was attributed to the poorer nutritional value of the diet as a consequence of the lower concentration of diatoms in the detrital aggregate. The reproductive characteristics of moggel were examined in four reservoirs. Moggel were able to reproduce successfully in the reservoirs. This could be attributed to their r-selected reproductive strategy, with a high fecundity and an extended spawning season and their ability to spawn in a floodplain environment. Differences in recruitment success between years were found to be a consequence of the timing and duration of seasonal rains. The number of mature females in a population and the availability of suitable spawning habitat influenced recruitment success. The life history of the moggel in five reservoirs was compared. Growth appeared to be related to food availability, while mortality was lower in the populations where food was abundant and there were less predatory species. Size and age at maturity were not affected by environmental factors, but were dependent on growth and mortality. Three contrasting methods were used to estimate moggel gillnet selectivity. The Sechin, direct fyke net method and length-structured model all yielded similar results and correction factors obtained from the selectivity study were applied to the gillnet data to estimate the fish population size and structure in each reservoir. Using information from the life history and selectivity studies, the biomass and production of five moggel populations was estimated and related to abiotic and biotic factors in the reservoirs and their catchments. Moggel biomass and production was dependent on the biomass of algae, which was dependent on morphoedaphic characteristics of the reservoirs. Small, shallow reservoirs with a reasonable amount of human habitation in their catchments would sustain the highest algal biomass and provided they had adequate spawning habitat would also have the highest moggel biomass and production. The future research requirements for small reservoir fisheries are outlined and include a three-year program to develop a species-specific production model for any of the dominant species.
- Full Text:
Sulphide-enhanced hydrolysis of primary sewage sludge : implications for the bioremediation of sulphate-enriched wastewaters
- Whittington-Jones, Kevin John
- Authors: Whittington-Jones, Kevin John
- Date: 2000
- Subjects: Bioremediation Sewage sludge Hydrolysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3910 , http://hdl.handle.net/10962/d1003969
- Description: The potential application of sulphate reducing bacteria for the bioremediation of acid mine drainage has already been recognised, and offers significant financial advantages over conventional chemical treatment approaches. Although the technology has been demonstrated successfully on both small- and large-scale, it’s extensive implementation has been constrained by the provision of suitable and cost effective electron donor and carbon sources. Primary sewage sludge is readily available in large quantities, but the slow rate of solubilization and low yield of soluble products do not apparently favour its use for this application. A number of pre-treatment steps have been introduced in an attempt to improve the yield and rates under methanogenic conditions. However, although early work suggested that degradation of lignocellulose and proteins may be more rapid under sulphate reducing conditions, the fate of primary sewage sludge under these conditions has been ignored. It was proposed that by combining the hydrolysis of primary sewage sludge and biological sulphate reduction, in a settling sludge bed, both processes would be enhanced. The aim of this study was to test this hypothesis on laboratory- and pilot-scale, and attempt to elucidate the underlying mechanism involved. The solubilization of primary sewage sludge was enhanced in the presence of sulphate reduction in continuous laboratory-scale reactors. Particulate matter accumulated in the bed of non-sulphidogenic systems, but not in sulphidogenic ones. This was attributed to increased solubilization and the smaller average floc size in the latter. Solubilization occurred within the settling sludge bed of the reactors, and offered a possible explanation for the better performance of the multiple- over single-stage reactor. A pilot-scale Falling Sludge Bed Reactor was constructed at Grootvlei Gold Mine, Springs, South Africa, and resulted in the solubilization of more than 70% of the influent primary sewage sludge. The system was also found to be highly resilient to severe perturbations, and returned rapidly to steady-state. Flask studies revealed that the hydrolysis of both proteins and complex carbohydrates was accelerated in the presence of biological sulphate reduction or sulphide. A study of the enzymology of sludge digestion revealed that sulphate reduction had little direct effect on the activity of the hydrolytic enzymes, but that reactor design was critical in the prevention of washout of these enzymes. Finally, a descriptive model was developed to explain the enhanced hydrolysis of primary sewage sludge. The model incorporated the effect of sulphidogenesis on floc fracture and reflocculation, and likely implications for mass transfer limitations.
- Full Text:
- Authors: Whittington-Jones, Kevin John
- Date: 2000
- Subjects: Bioremediation Sewage sludge Hydrolysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3910 , http://hdl.handle.net/10962/d1003969
- Description: The potential application of sulphate reducing bacteria for the bioremediation of acid mine drainage has already been recognised, and offers significant financial advantages over conventional chemical treatment approaches. Although the technology has been demonstrated successfully on both small- and large-scale, it’s extensive implementation has been constrained by the provision of suitable and cost effective electron donor and carbon sources. Primary sewage sludge is readily available in large quantities, but the slow rate of solubilization and low yield of soluble products do not apparently favour its use for this application. A number of pre-treatment steps have been introduced in an attempt to improve the yield and rates under methanogenic conditions. However, although early work suggested that degradation of lignocellulose and proteins may be more rapid under sulphate reducing conditions, the fate of primary sewage sludge under these conditions has been ignored. It was proposed that by combining the hydrolysis of primary sewage sludge and biological sulphate reduction, in a settling sludge bed, both processes would be enhanced. The aim of this study was to test this hypothesis on laboratory- and pilot-scale, and attempt to elucidate the underlying mechanism involved. The solubilization of primary sewage sludge was enhanced in the presence of sulphate reduction in continuous laboratory-scale reactors. Particulate matter accumulated in the bed of non-sulphidogenic systems, but not in sulphidogenic ones. This was attributed to increased solubilization and the smaller average floc size in the latter. Solubilization occurred within the settling sludge bed of the reactors, and offered a possible explanation for the better performance of the multiple- over single-stage reactor. A pilot-scale Falling Sludge Bed Reactor was constructed at Grootvlei Gold Mine, Springs, South Africa, and resulted in the solubilization of more than 70% of the influent primary sewage sludge. The system was also found to be highly resilient to severe perturbations, and returned rapidly to steady-state. Flask studies revealed that the hydrolysis of both proteins and complex carbohydrates was accelerated in the presence of biological sulphate reduction or sulphide. A study of the enzymology of sludge digestion revealed that sulphate reduction had little direct effect on the activity of the hydrolytic enzymes, but that reactor design was critical in the prevention of washout of these enzymes. Finally, a descriptive model was developed to explain the enhanced hydrolysis of primary sewage sludge. The model incorporated the effect of sulphidogenesis on floc fracture and reflocculation, and likely implications for mass transfer limitations.
- Full Text:
Student-teachers' perspectives of the role of environmental education in geography education
- Authors: Symmonds, Joanne
- Date: 1997
- Subjects: Geography -- Study and teaching -- Environmental aspects Environmental education
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1776 , http://hdl.handle.net/10962/d1003661
- Description: The ideas contained in socially critical Environmental Education cannot be ignored given the current environmental crisis and the need to achieve democracy in South African society. In order to achieve this learners need to develop the skills to make informed decisions which will facilitate the achievement of a sustainable society. It is the contention of this research that a socially critical Environmental Education approach to education can facilitate the above. Teachers of formal secondary school Geography Education are in the position to implement socially critical Environmental Education into their teaching. This study therefore investigates the perspectives of student teachers regarding the role of Environmental Education in secondary school Geography Education. This was done within the Interpretative Paradigm using a case study which involved five Higher Diploma in Education Geography method students. The research has revealed that even though the Geography method students have been exposed to an Environmental Education course, in their teaching preparation and are motivated to use it, they have limited understanding of the theory underpinning Environmental Education and how to apply it to their Geography teaching. The problems of bridging theory and practice was apparent. Recommendations are made as how to best facilitate the gap between theory and practice.
- Full Text:
- Authors: Symmonds, Joanne
- Date: 1997
- Subjects: Geography -- Study and teaching -- Environmental aspects Environmental education
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1776 , http://hdl.handle.net/10962/d1003661
- Description: The ideas contained in socially critical Environmental Education cannot be ignored given the current environmental crisis and the need to achieve democracy in South African society. In order to achieve this learners need to develop the skills to make informed decisions which will facilitate the achievement of a sustainable society. It is the contention of this research that a socially critical Environmental Education approach to education can facilitate the above. Teachers of formal secondary school Geography Education are in the position to implement socially critical Environmental Education into their teaching. This study therefore investigates the perspectives of student teachers regarding the role of Environmental Education in secondary school Geography Education. This was done within the Interpretative Paradigm using a case study which involved five Higher Diploma in Education Geography method students. The research has revealed that even though the Geography method students have been exposed to an Environmental Education course, in their teaching preparation and are motivated to use it, they have limited understanding of the theory underpinning Environmental Education and how to apply it to their Geography teaching. The problems of bridging theory and practice was apparent. Recommendations are made as how to best facilitate the gap between theory and practice.
- Full Text:
Anorogenic alkaline ring-type complexes of the Damaraland Province, Namibia, and their economic potential
- Authors: Potgieter, J E
- Date: 1987
- Subjects: Alkalic igneous rocks -- Namibia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4907 , http://hdl.handle.net/10962/d1001567
- Description: Anorogenic alkaline ring-type complexes form within continental plate settings. Alkaline magmatism is derived from the upper mantle, in which mantle metasomatism plays an important part, as well as from partial melting of the lower crust. Radial and concentric fractures develop during the ascent of alkaline magma. Extrusion of basic and felsic magma takes place along these fractures with felsic volcanics building-up central volcanoes. As a result of emptying of the magma chamber, the superstructure of the volcano collapses and a caldera is formed. During the caldera stage syenitic and granitic material are intruded into ring fractures. Alkaline ring-type complexes may be classified as (i) alkaline qranite and syenite-type and (ii) carbonatite and undersaturated-type. These ring-type complexes occur as distinct igneous provinces. Some major provinces occur in Brazil, Corsica, Namibia, Nigeria, Norway, Saudi-Arabia and Sudan. In Namibia the Damaraland igneous province is of Mesozoic aqe and it contains 15 alkaline ring-type complexes . These complexes are situated along north-eastern trends which correspond to transform directions of the South Atlantic. During the opening of the South Atlantic (Gondwana breakup) Pan-African age lineaments were reactivated which allowed emplacement of anorogenic alkaline magmatism. A zonation of alkaline granite and syenitetype in the west and carbonatite and undersaturated-type ring-complexes in the east correlates with down- and upwarp axes parallel to the line of Gondwana fragmentation. Alkali- and H⁺-metasomatism is related to the alkaline and syenite-type whereas alkali metasomatism (fenitization) is associated with carbonatite and undersaturated-type ring-complexes. Sn, W and Ta mineralization is associated with alkaline granites of some of the alkaline granite and syenite-type ring-complexes. Fe, F, PO₄ , Nb, Th, REE, Sr, Zn and Pb mineralization is associated with carbonatite complexes. Potential exists for: (i) porphyry Cu-Mo and epithermal-type (Au, Ag, Pt-metals, base metals) mineralization in the alkaline granite and syenite-type ring-complexes and (ii) disseminated Cu, Au, Aq and Pt-metals in carbonatite and undersaturated-type ring-complexes
- Full Text:
- Authors: Potgieter, J E
- Date: 1987
- Subjects: Alkalic igneous rocks -- Namibia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4907 , http://hdl.handle.net/10962/d1001567
- Description: Anorogenic alkaline ring-type complexes form within continental plate settings. Alkaline magmatism is derived from the upper mantle, in which mantle metasomatism plays an important part, as well as from partial melting of the lower crust. Radial and concentric fractures develop during the ascent of alkaline magma. Extrusion of basic and felsic magma takes place along these fractures with felsic volcanics building-up central volcanoes. As a result of emptying of the magma chamber, the superstructure of the volcano collapses and a caldera is formed. During the caldera stage syenitic and granitic material are intruded into ring fractures. Alkaline ring-type complexes may be classified as (i) alkaline qranite and syenite-type and (ii) carbonatite and undersaturated-type. These ring-type complexes occur as distinct igneous provinces. Some major provinces occur in Brazil, Corsica, Namibia, Nigeria, Norway, Saudi-Arabia and Sudan. In Namibia the Damaraland igneous province is of Mesozoic aqe and it contains 15 alkaline ring-type complexes . These complexes are situated along north-eastern trends which correspond to transform directions of the South Atlantic. During the opening of the South Atlantic (Gondwana breakup) Pan-African age lineaments were reactivated which allowed emplacement of anorogenic alkaline magmatism. A zonation of alkaline granite and syenitetype in the west and carbonatite and undersaturated-type ring-complexes in the east correlates with down- and upwarp axes parallel to the line of Gondwana fragmentation. Alkali- and H⁺-metasomatism is related to the alkaline and syenite-type whereas alkali metasomatism (fenitization) is associated with carbonatite and undersaturated-type ring-complexes. Sn, W and Ta mineralization is associated with alkaline granites of some of the alkaline granite and syenite-type ring-complexes. Fe, F, PO₄ , Nb, Th, REE, Sr, Zn and Pb mineralization is associated with carbonatite complexes. Potential exists for: (i) porphyry Cu-Mo and epithermal-type (Au, Ag, Pt-metals, base metals) mineralization in the alkaline granite and syenite-type ring-complexes and (ii) disseminated Cu, Au, Aq and Pt-metals in carbonatite and undersaturated-type ring-complexes
- Full Text:
Effect of anticonvulsant agents on pineal gland indole metabolism
- Authors: Morton, Dougal John
- Date: 1983
- Subjects: Pineal gland -- Metabolism Anticonvulsants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3844 , http://hdl.handle.net/10962/d1009518
- Description: Preface: The general indications that the pineal gland might be involved in homeostasis, and more specifically the evidence suggesting a role in amelioration of seizure states warranted further investigation . No reports had examined a possible link between anticonvulsant drug administration and pineal gland function, and few enabled any type of presumption to be made as to possible effects. This study was an attempt to evaluate in which ways anticonvulsant drugs might alter pineal gland indole metabolism, with a view to increasing understanding of the role of the pineal in modulation of epileptic discharges. In order to make the study as meaningful as possible extensive preliminary investigations were necessary. Pharmacokinetic determinations gave an indication of tissue concentrations of the drugs, which could then be related to observed effects. As far as possible, where existing information was lacking, the catalytic behaviour of the various enzymes was characterised in order to explain any observed effects at a molecular level. An attempt was also made to characterise the regulatory mechanisms controlling indole metabolism, again in order to define the pharmacological effects exerted by the drugs used. The complexity of the system made it impossible to suggest a single uniform regulatory hypothesis, although some significant observations were made. Finally, the studies involving the anticonvulsant drugs were conducted on intact animals, isolated organs and individual enzymes in an attempt to determine whether the observed effects were occuring at a molecular, local or central level.
- Full Text:
- Authors: Morton, Dougal John
- Date: 1983
- Subjects: Pineal gland -- Metabolism Anticonvulsants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3844 , http://hdl.handle.net/10962/d1009518
- Description: Preface: The general indications that the pineal gland might be involved in homeostasis, and more specifically the evidence suggesting a role in amelioration of seizure states warranted further investigation . No reports had examined a possible link between anticonvulsant drug administration and pineal gland function, and few enabled any type of presumption to be made as to possible effects. This study was an attempt to evaluate in which ways anticonvulsant drugs might alter pineal gland indole metabolism, with a view to increasing understanding of the role of the pineal in modulation of epileptic discharges. In order to make the study as meaningful as possible extensive preliminary investigations were necessary. Pharmacokinetic determinations gave an indication of tissue concentrations of the drugs, which could then be related to observed effects. As far as possible, where existing information was lacking, the catalytic behaviour of the various enzymes was characterised in order to explain any observed effects at a molecular level. An attempt was also made to characterise the regulatory mechanisms controlling indole metabolism, again in order to define the pharmacological effects exerted by the drugs used. The complexity of the system made it impossible to suggest a single uniform regulatory hypothesis, although some significant observations were made. Finally, the studies involving the anticonvulsant drugs were conducted on intact animals, isolated organs and individual enzymes in an attempt to determine whether the observed effects were occuring at a molecular, local or central level.
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The Karoo caterpillar Loxostege Frustalis Zeller (Lepidoptera : Pyralidae) in relation to its host plants and natural enemies
- Authors: Möhr, Johann Diederich
- Date: 1982
- Subjects: Caterpillars -- South Africa Lepidoptera -- Host plants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5604 , http://hdl.handle.net/10962/d1002054
- Description: The Karoo is an arid inland plateau in the central and northeastern Cape Province of South Africa and is characterised by sparse, stunted vegetation. The vegetation is rich in species, and over large areas species of Pentzia, which are drought-resistant shrubs, are extremely abundant. These plants are food for stock (mainly sheep), and because the larvae of the Karoo caterpillar periodically occur in sufficient numbers to defoliate the plants, they assume pest status. Fully-fed Loxostege frustalis larvae construct cases in the soil beneath their food plants and they overwinter in these cases. A census of the numbers of larval cases accumulated in the soil, conducted from 1975 to 1980, showed that an expanded distribution of the pentzias is responsible for the periodic larval outbreaks. Further, alternate food plants are an important food supply for L. frustalis larvae when they disperse under crowded conditions The census data for L. frustalis were analysed by constructing partial life tables for the life-history period from case construction to moth emergence. The mortality of 'encased larvae' is useful for assessing the impact of the known L. frustalis natural enemies. The most important natural enemies were the braconids Chelonus curvimaculatus Cameron, Macrocentrus maraisi Nixon and the fungus Beauveria bassiana (Balsamo) Vuillemin. The collective responses of all the natural enemies to the density of L. frustalis encased larvae was direct, but undercompensating, so that areas with more pentzias produced more L. frustais. Strategies for immediate measures to alleviate the Karoo caterpillar problem, and for future research, are discussed. It is concluded that reduction of pentzia populations to acceptable levels and/or supplementing pastures with non-host plants of L. frustalis offer the only practical solutions to the Karoo caterpillar problem. Biological control of L. frustalis is dismissed as an option for reducing the pest status of the Karoo caterpillar
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- Authors: Möhr, Johann Diederich
- Date: 1982
- Subjects: Caterpillars -- South Africa Lepidoptera -- Host plants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5604 , http://hdl.handle.net/10962/d1002054
- Description: The Karoo is an arid inland plateau in the central and northeastern Cape Province of South Africa and is characterised by sparse, stunted vegetation. The vegetation is rich in species, and over large areas species of Pentzia, which are drought-resistant shrubs, are extremely abundant. These plants are food for stock (mainly sheep), and because the larvae of the Karoo caterpillar periodically occur in sufficient numbers to defoliate the plants, they assume pest status. Fully-fed Loxostege frustalis larvae construct cases in the soil beneath their food plants and they overwinter in these cases. A census of the numbers of larval cases accumulated in the soil, conducted from 1975 to 1980, showed that an expanded distribution of the pentzias is responsible for the periodic larval outbreaks. Further, alternate food plants are an important food supply for L. frustalis larvae when they disperse under crowded conditions The census data for L. frustalis were analysed by constructing partial life tables for the life-history period from case construction to moth emergence. The mortality of 'encased larvae' is useful for assessing the impact of the known L. frustalis natural enemies. The most important natural enemies were the braconids Chelonus curvimaculatus Cameron, Macrocentrus maraisi Nixon and the fungus Beauveria bassiana (Balsamo) Vuillemin. The collective responses of all the natural enemies to the density of L. frustalis encased larvae was direct, but undercompensating, so that areas with more pentzias produced more L. frustais. Strategies for immediate measures to alleviate the Karoo caterpillar problem, and for future research, are discussed. It is concluded that reduction of pentzia populations to acceptable levels and/or supplementing pastures with non-host plants of L. frustalis offer the only practical solutions to the Karoo caterpillar problem. Biological control of L. frustalis is dismissed as an option for reducing the pest status of the Karoo caterpillar
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A study of factors affecting precision in atomic absorption spectrometry
- Roos, Johannes Tielman Hofmeyr
- Authors: Roos, Johannes Tielman Hofmeyr
- Date: 1976
- Subjects: Atomic absorption spectroscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4490 , http://hdl.handle.net/10962/d1013080
- Description: 1. The effect of deviations from Beer's law on the precision of atomic absorption analysis has been examined from a theoretical point of view, and a function has been derived which makes it possible to evaluate quantitatively the effect of calibration curvature on the precision of analysis. The influence of incomplete sample volatilization on calibration curvature has been briefly investigated. 2. Possible error sources in atomic absorption spectrometry have been classified according to the "error function" (i.e., the dependence, upon transmittance T, of the uncertainty dT in a given transmittance measurement) with which they are associated. The magnitude of the contribution from each component function to the overall error function has been evaluated quantitatively, and it has been shown that the major component in nearly every case examined is that associated with the dynamic nature of the flame. Concentration ranges for optimum precision are suggested. 3. The effect of varying instrumental parameters on precision has been investigated, and generalized conditions for best precision have been ascertained. 4. The effect of an initial solvent extraction step on the precision of atomic absorption has been investigated for the elements copper and lead. It is shown that solvent extraction may be used to improve both the analytical sensitivity and the precision of analysis when very low concentrations of metal are determined. 5. The precision of analytical methods involving atomic absorption spectrometry has been studied, and the standard deviations compared with those obtained for the analysis of similar samples by means of a variety of other methods of analysis, both instrumental and classical.
- Full Text:
- Authors: Roos, Johannes Tielman Hofmeyr
- Date: 1976
- Subjects: Atomic absorption spectroscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4490 , http://hdl.handle.net/10962/d1013080
- Description: 1. The effect of deviations from Beer's law on the precision of atomic absorption analysis has been examined from a theoretical point of view, and a function has been derived which makes it possible to evaluate quantitatively the effect of calibration curvature on the precision of analysis. The influence of incomplete sample volatilization on calibration curvature has been briefly investigated. 2. Possible error sources in atomic absorption spectrometry have been classified according to the "error function" (i.e., the dependence, upon transmittance T, of the uncertainty dT in a given transmittance measurement) with which they are associated. The magnitude of the contribution from each component function to the overall error function has been evaluated quantitatively, and it has been shown that the major component in nearly every case examined is that associated with the dynamic nature of the flame. Concentration ranges for optimum precision are suggested. 3. The effect of varying instrumental parameters on precision has been investigated, and generalized conditions for best precision have been ascertained. 4. The effect of an initial solvent extraction step on the precision of atomic absorption has been investigated for the elements copper and lead. It is shown that solvent extraction may be used to improve both the analytical sensitivity and the precision of analysis when very low concentrations of metal are determined. 5. The precision of analytical methods involving atomic absorption spectrometry has been studied, and the standard deviations compared with those obtained for the analysis of similar samples by means of a variety of other methods of analysis, both instrumental and classical.
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Opname van die Kaapse Middelland en Karroogebied: deel 1: n Geografiese studie van die Kaapse middelland- en Karroogebied, met spesiale verwysing na die fisiografie en elemente van bodembenutting
- Authors: Badenhorst, J J
- Date: 1970
- Subjects: Geology -- South Africa Geomorphology -- South Africa Agriculture -- South Africa Orange/fish river project Sheep -- South Africa Goats -- South Africa Chicory -- South Africa Pineapple industry -- South Africa Feeds -- South Africa Forests and forestry -- South Africa Fruit -- South Africa South Africa -- Climate South Africa -- Geography
- Language: Afrikaans
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2612 , vital:20309
- Description: In 1966 het die Karoo-ontwikkelingvereniging die Universiteit Rhodes genader met 'n versoek dat die Universiteit Rhodes se Instituut vir Sosiale en Ekonomiese Navorsing 'n sosio-ekonomiese Opname van hulle streek sou maak om 'n feitegrondslag vir ontwikkelingsbeplanning te verskaf in afwagting van die voltooiing van die Oranjerivier-projek. Soortgelyke versoeke is van die Middellande-Ontwikkelingsvereniging en die Vereniging van Openbare Liggame van die Suid-Oostelike Distrikte ontvang. Nadat die Departement van Beplanning, wat die idee van 'n streeksopname sterk ondersteun het, geraadpleeg is, is daar ooreengekom dat hoewel Port Elizabeth en sy agterland 'n gemeenskaplike ekonomiese eenheid vorm, die gebied onderverdeel kon word, en dat die Universiteit van Port Elizabeth verantwoordelikheid vir die stedelike gebied Port Elizabeth en Uitenhage sou aanvaar, en die Universiteit Rhodes, deur die Instituut vir Sosiale en Ekonomiese Navorsing die Opname van die binnelandse gebiede sou lei. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
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- Authors: Badenhorst, J J
- Date: 1970
- Subjects: Geology -- South Africa Geomorphology -- South Africa Agriculture -- South Africa Orange/fish river project Sheep -- South Africa Goats -- South Africa Chicory -- South Africa Pineapple industry -- South Africa Feeds -- South Africa Forests and forestry -- South Africa Fruit -- South Africa South Africa -- Climate South Africa -- Geography
- Language: Afrikaans
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2612 , vital:20309
- Description: In 1966 het die Karoo-ontwikkelingvereniging die Universiteit Rhodes genader met 'n versoek dat die Universiteit Rhodes se Instituut vir Sosiale en Ekonomiese Navorsing 'n sosio-ekonomiese Opname van hulle streek sou maak om 'n feitegrondslag vir ontwikkelingsbeplanning te verskaf in afwagting van die voltooiing van die Oranjerivier-projek. Soortgelyke versoeke is van die Middellande-Ontwikkelingsvereniging en die Vereniging van Openbare Liggame van die Suid-Oostelike Distrikte ontvang. Nadat die Departement van Beplanning, wat die idee van 'n streeksopname sterk ondersteun het, geraadpleeg is, is daar ooreengekom dat hoewel Port Elizabeth en sy agterland 'n gemeenskaplike ekonomiese eenheid vorm, die gebied onderverdeel kon word, en dat die Universiteit van Port Elizabeth verantwoordelikheid vir die stedelike gebied Port Elizabeth en Uitenhage sou aanvaar, en die Universiteit Rhodes, deur die Instituut vir Sosiale en Ekonomiese Navorsing die Opname van die binnelandse gebiede sou lei. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
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Electron precipitation and ionospheric disturbance
- Authors: Torr, Marsha R
- Date: 1966
- Subjects: Electrons , Electron precipitation , Ionosphere , Ionospheric electron density
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5509 , http://hdl.handle.net/10962/d1007691
- Description: From Introduction: The minimum in the scalar magnitude of the geographic total field, which lies off the coast of Brazil, allows the mirror points of trapped particles to dip low into the atmosphere over the South Atlantic Ocean, resulting in two regions of maximum intensity of preciptated particles in that region, one from the inner belt and one from the outer. High charged particle fluxes have been observed at low altitudes over these regions by satellites Sputnik 5 and 6 (Ginsburg et al, 1961) and Discoverer 31 (Seward and Kornblum, 1963) amongst others. The more southerly of these two regions acts as a sink for electrons from the outer radiation belt and will be referred to in what follows as the Southern Radiation Anomaly. Gladhill and van Rooyen (1963) predicted that the energy deposited in the upper atmosphere by these charged particles would be sufficient to give rise to enhanced geophysical effects such as auroral emission, X-rays and ionization and heating of the upper atmosphere in this region. Although some of these effects have been correlated with precipitated electrons, no definite relation had until now been established between ionospheric effects and precipitated particles. The aim of this thesis was to investigate such a relationship and the results were extremely successful. It will be shown conclusively in what follows, that the precipitation of electrons can account for the ionospheric disturbances defined by a disturbance criterion at all stations around L=4. Part I describes the exploration of the radiation belts and the magnetosphere with rockets and satellites. The resulting theoretical models based on the observations are discussed. A brief review is given of the work that has been done to date to derive equations for the loss and replenishment of particles in the belts. Because of the complexity of these and the number of doubtful factors involved, a simple model of injection of electrons into the outer belt is devised, giving average values of trapped and precipitated electron fluxes at any point around L=4. In Part II, this model is employed together with the disturbance criterion of Gledhill and Torr (1965) to examine the relationship between ionospheric disturbances and electron fluxes. Also the energy range of the precipitated particles is examined.
- Full Text:
- Authors: Torr, Marsha R
- Date: 1966
- Subjects: Electrons , Electron precipitation , Ionosphere , Ionospheric electron density
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5509 , http://hdl.handle.net/10962/d1007691
- Description: From Introduction: The minimum in the scalar magnitude of the geographic total field, which lies off the coast of Brazil, allows the mirror points of trapped particles to dip low into the atmosphere over the South Atlantic Ocean, resulting in two regions of maximum intensity of preciptated particles in that region, one from the inner belt and one from the outer. High charged particle fluxes have been observed at low altitudes over these regions by satellites Sputnik 5 and 6 (Ginsburg et al, 1961) and Discoverer 31 (Seward and Kornblum, 1963) amongst others. The more southerly of these two regions acts as a sink for electrons from the outer radiation belt and will be referred to in what follows as the Southern Radiation Anomaly. Gladhill and van Rooyen (1963) predicted that the energy deposited in the upper atmosphere by these charged particles would be sufficient to give rise to enhanced geophysical effects such as auroral emission, X-rays and ionization and heating of the upper atmosphere in this region. Although some of these effects have been correlated with precipitated electrons, no definite relation had until now been established between ionospheric effects and precipitated particles. The aim of this thesis was to investigate such a relationship and the results were extremely successful. It will be shown conclusively in what follows, that the precipitation of electrons can account for the ionospheric disturbances defined by a disturbance criterion at all stations around L=4. Part I describes the exploration of the radiation belts and the magnetosphere with rockets and satellites. The resulting theoretical models based on the observations are discussed. A brief review is given of the work that has been done to date to derive equations for the loss and replenishment of particles in the belts. Because of the complexity of these and the number of doubtful factors involved, a simple model of injection of electrons into the outer belt is devised, giving average values of trapped and precipitated electron fluxes at any point around L=4. In Part II, this model is employed together with the disturbance criterion of Gledhill and Torr (1965) to examine the relationship between ionospheric disturbances and electron fluxes. Also the energy range of the precipitated particles is examined.
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Studies on Paragus (Diptera, Syrphidae)
- Authors: Stuckenberg, B R
- Date: 1953
- Subjects: Syrphidae , Diptera
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5887 , http://hdl.handle.net/10962/d1013321
- Description: As several new species are described in this thesis its full value can only be realised by its publication, and it has therefore been prepared with that end in view. The subject matter is divided into two parts, each of which has been treated quite independently of the other. Both parts are presented here in the form in which they have been offered for publication. The first paper consists of a systematic study of a complex of species within the genus Paragus. It includes descriptions of four new species, a new subspecies, an allotype, and redescriptions of two incompletely defined species. This paper has been offered for publication in the Transactions of the Royal Entomological Society of London. The second part consists of a study of all the Ethiopian species of Paragus except those covered by the first paper. It includes the definition of a new subgenus, and descriptions of two new species and three allotypes. It has been sent for publication in the "Revue Zoologie et Botanique de Africaine" at the invitation of Dr. P. Basilewsky of the Musee du Congo Belge, Tervuren.
- Full Text:
- Authors: Stuckenberg, B R
- Date: 1953
- Subjects: Syrphidae , Diptera
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5887 , http://hdl.handle.net/10962/d1013321
- Description: As several new species are described in this thesis its full value can only be realised by its publication, and it has therefore been prepared with that end in view. The subject matter is divided into two parts, each of which has been treated quite independently of the other. Both parts are presented here in the form in which they have been offered for publication. The first paper consists of a systematic study of a complex of species within the genus Paragus. It includes descriptions of four new species, a new subspecies, an allotype, and redescriptions of two incompletely defined species. This paper has been offered for publication in the Transactions of the Royal Entomological Society of London. The second part consists of a study of all the Ethiopian species of Paragus except those covered by the first paper. It includes the definition of a new subgenus, and descriptions of two new species and three allotypes. It has been sent for publication in the "Revue Zoologie et Botanique de Africaine" at the invitation of Dr. P. Basilewsky of the Musee du Congo Belge, Tervuren.
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