An investigation of Grade 11 Oshindonga teachers' understanding and implementation of the learner-centered approach adopted in Namibia : a case study
- Mbangula, Christofina Nalweendo
- Authors: Mbangula, Christofina Nalweendo
- Date: 2011
- Subjects: Student-centered learning -- Namibia Ndonga language -- Study and teaching -- Namibia Teachers -- Training of -- Namibia Educational change -- Namibia Education -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1628 , http://hdl.handle.net/10962/d1003510
- Description: Before the Republic of Namibia achieved independence in 1990, Bantu Education was the prevailing structure used to promote the social, economic, and political ethos of apartheid through a teacher-centered education system. After 1990, Namibia underwent a major restructuring of education. Learner-centered education was introduced as an inclusive and participatory approach to achieve the reform goals. One of the aims was to review the existing Language policy and to promote mother tongue teaching, since it is through language we internalize our experience and construct our own understanding. In other words, our cognitive, emotional and social development is dependent on language. In this case study, the understanding and implementation of a learner-centered approach in Namibia were investigated in order to gain insights about how the participating education officer, responsible for Oshindonga understands and assists teachers to implement this approach. At the same time, this study aimed at investigating Grade 11 teachers‟ understanding and implementation of LCE in their classrooms. The qualitative methodology in this case study used semi-structured interviews, classroom observations and document analysis for data collection. The data revealed that there are a number of misconceptions. In some cases, what teachers say is not what they do. The findings suggest that teachers, while attempting to implement a learner-centered approach, are not confident about its underlying theory, and therefore the degree of implementation depends on how the teachers used their understanding of that theory in their practice within these conceptual constraints. The study highlights particular challenges and problems that hinder the effective implementation of learner-centered education.
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- Authors: Mbangula, Christofina Nalweendo
- Date: 2011
- Subjects: Student-centered learning -- Namibia Ndonga language -- Study and teaching -- Namibia Teachers -- Training of -- Namibia Educational change -- Namibia Education -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1628 , http://hdl.handle.net/10962/d1003510
- Description: Before the Republic of Namibia achieved independence in 1990, Bantu Education was the prevailing structure used to promote the social, economic, and political ethos of apartheid through a teacher-centered education system. After 1990, Namibia underwent a major restructuring of education. Learner-centered education was introduced as an inclusive and participatory approach to achieve the reform goals. One of the aims was to review the existing Language policy and to promote mother tongue teaching, since it is through language we internalize our experience and construct our own understanding. In other words, our cognitive, emotional and social development is dependent on language. In this case study, the understanding and implementation of a learner-centered approach in Namibia were investigated in order to gain insights about how the participating education officer, responsible for Oshindonga understands and assists teachers to implement this approach. At the same time, this study aimed at investigating Grade 11 teachers‟ understanding and implementation of LCE in their classrooms. The qualitative methodology in this case study used semi-structured interviews, classroom observations and document analysis for data collection. The data revealed that there are a number of misconceptions. In some cases, what teachers say is not what they do. The findings suggest that teachers, while attempting to implement a learner-centered approach, are not confident about its underlying theory, and therefore the degree of implementation depends on how the teachers used their understanding of that theory in their practice within these conceptual constraints. The study highlights particular challenges and problems that hinder the effective implementation of learner-centered education.
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An investigation of how visual arts can be used to teach mathematical concepts of space and shape in Grade R
- Authors: Schäfer, Jean Stewart
- Date: 2011
- Subjects: Rhodes University. Deptartment of Education , Mathematics -- Study and teaching (Elementary) -- South Africa--Grahamstown , Mathematics teachers -- Training of -- South Africa -- Grahamstown , Early childhood education -- South Africa -- Grahamstown , Kindergarten -- Activity programs -- South Africa -- Grahamstown , Creative activities and seat work -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1632 , http://hdl.handle.net/10962/d1003514 , Rhodes University. Deptartment of Education , Mathematics -- Study and teaching (Elementary) -- South Africa--Grahamstown , Mathematics teachers -- Training of -- South Africa -- Grahamstown , Early childhood education -- South Africa -- Grahamstown , Kindergarten -- Activity programs -- South Africa -- Grahamstown , Creative activities and seat work -- South Africa -- Grahamstown
- Description: The impetus for this study came from the findings of an evaluation of a Maths and Science through Arts and Culture (MStAC) Curriculum Intervention undertaken with Grade R teachers registered for a BEd(in-service) qualification at Rhodes University, South Africa. The intervention aimed to enrich Grade R teachers’ teaching of mathematics. Post-intervention classroom observations showed that, in spite of the intervention, teachers’ classroom practices did not change, and they were not using visual arts to teach mathematical concepts. This, together with the lack of research in the field of mathematics in early childhood, particularly in South Africa, motivated this research, a case study, which investigates how visual arts can be used to teach space and shape conceptualization in Grade R. I designed a research intervention underpinned by a constructivist model of teacher professional development located in reflective practice (Borko & Putman, 1995; Zeichner & Liston, 1996; Wilmot, 2005). Guided by Stacey’s (2009) notion of an emergent curriculum, I designed a three phase research intervention which involved selected Grade R teachers undertaking classroom-based research. Phase I built awareness around the notion of creativity; Phase II focused on making meaning of children’s behaviour and interests; and Phase III applied the knowledge and ideas from the Phases I and II to the teaching of space and shape. As an interpretive research study, it closely examines the participating teachers’ perceptions, experiences and reflections which were articulated in reflective reports and assignments. Following action research processes, the participant teachers engaged in the process of an emergent curriculum. They observed the behaviour interests of Grade R children, interpreted and made meaning of the evident behaviours, made decisions regarding extension activities, and planned accordingly. The findings of the study illuminate a model of teacher professional development that can support and enhance teachers’ practice. Understanding the notion of creativity and the ability to create a classroom conducive to creativity, are necessary components for teaching space and shape through visual arts activities. An emergent curriculum approach is proposed as an appropriate pedagogy for teaching children about space and shape through visual arts activities.
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- Authors: Schäfer, Jean Stewart
- Date: 2011
- Subjects: Rhodes University. Deptartment of Education , Mathematics -- Study and teaching (Elementary) -- South Africa--Grahamstown , Mathematics teachers -- Training of -- South Africa -- Grahamstown , Early childhood education -- South Africa -- Grahamstown , Kindergarten -- Activity programs -- South Africa -- Grahamstown , Creative activities and seat work -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1632 , http://hdl.handle.net/10962/d1003514 , Rhodes University. Deptartment of Education , Mathematics -- Study and teaching (Elementary) -- South Africa--Grahamstown , Mathematics teachers -- Training of -- South Africa -- Grahamstown , Early childhood education -- South Africa -- Grahamstown , Kindergarten -- Activity programs -- South Africa -- Grahamstown , Creative activities and seat work -- South Africa -- Grahamstown
- Description: The impetus for this study came from the findings of an evaluation of a Maths and Science through Arts and Culture (MStAC) Curriculum Intervention undertaken with Grade R teachers registered for a BEd(in-service) qualification at Rhodes University, South Africa. The intervention aimed to enrich Grade R teachers’ teaching of mathematics. Post-intervention classroom observations showed that, in spite of the intervention, teachers’ classroom practices did not change, and they were not using visual arts to teach mathematical concepts. This, together with the lack of research in the field of mathematics in early childhood, particularly in South Africa, motivated this research, a case study, which investigates how visual arts can be used to teach space and shape conceptualization in Grade R. I designed a research intervention underpinned by a constructivist model of teacher professional development located in reflective practice (Borko & Putman, 1995; Zeichner & Liston, 1996; Wilmot, 2005). Guided by Stacey’s (2009) notion of an emergent curriculum, I designed a three phase research intervention which involved selected Grade R teachers undertaking classroom-based research. Phase I built awareness around the notion of creativity; Phase II focused on making meaning of children’s behaviour and interests; and Phase III applied the knowledge and ideas from the Phases I and II to the teaching of space and shape. As an interpretive research study, it closely examines the participating teachers’ perceptions, experiences and reflections which were articulated in reflective reports and assignments. Following action research processes, the participant teachers engaged in the process of an emergent curriculum. They observed the behaviour interests of Grade R children, interpreted and made meaning of the evident behaviours, made decisions regarding extension activities, and planned accordingly. The findings of the study illuminate a model of teacher professional development that can support and enhance teachers’ practice. Understanding the notion of creativity and the ability to create a classroom conducive to creativity, are necessary components for teaching space and shape through visual arts activities. An emergent curriculum approach is proposed as an appropriate pedagogy for teaching children about space and shape through visual arts activities.
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An investigation of teacher educators' perceptions and implementation of formative assessment at a college of education in Namibia : a case study
- Authors: Iileka, Ottilie
- Date: 2011
- Subjects: Teacher educators -- Namibia Educational evaluation -- Namibia Educational tests and measurements -- Namibia Academic achievement -- Testing -- Namibia Teachers -- Training of -- Namibia Universities and colleges -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1645 , http://hdl.handle.net/10962/d1003527
- Description: Changes in assessment practice in education are a global issue. Colleges of Education in Namibia also need to accommodate these changes in their training programs for student teachers, to model their practice of all modes of assessment in teaching and learning. Emphasis should be placed on assessment for learning, which is formative in nature. This qualitative case study investigated the following questions: How do teacher educators understand the principles and strategies of formative assessment and how do teacher educators implement formative assessment in their own teaching, which in turn serves as an example to their student teachers. I used three methods of collecting data: interviews, observation and document analysis. The data identify a range of findings in the teacher educators' professed understanding of formative assessment and how it is implemented in their own practice. The data also identify challenges facing the teacher educators in terms of setting a good example to their student teachers in the area of formative assessment. This study also offers suggestions for further studies on formative assessment. These include a suggestion for teacher educators to look at their own practice of formative assessment principles and strategies. A major cross department study could be conducted that includes teacher educators from different subject areas to see to how the implementation of formative assessment in the college varies from one department to another. A third possibility suggests a study involving student teachers from various areas of specialization in the college to see to what extent the implementation of formative assessment in the college affects their future assessment practices.
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- Authors: Iileka, Ottilie
- Date: 2011
- Subjects: Teacher educators -- Namibia Educational evaluation -- Namibia Educational tests and measurements -- Namibia Academic achievement -- Testing -- Namibia Teachers -- Training of -- Namibia Universities and colleges -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1645 , http://hdl.handle.net/10962/d1003527
- Description: Changes in assessment practice in education are a global issue. Colleges of Education in Namibia also need to accommodate these changes in their training programs for student teachers, to model their practice of all modes of assessment in teaching and learning. Emphasis should be placed on assessment for learning, which is formative in nature. This qualitative case study investigated the following questions: How do teacher educators understand the principles and strategies of formative assessment and how do teacher educators implement formative assessment in their own teaching, which in turn serves as an example to their student teachers. I used three methods of collecting data: interviews, observation and document analysis. The data identify a range of findings in the teacher educators' professed understanding of formative assessment and how it is implemented in their own practice. The data also identify challenges facing the teacher educators in terms of setting a good example to their student teachers in the area of formative assessment. This study also offers suggestions for further studies on formative assessment. These include a suggestion for teacher educators to look at their own practice of formative assessment principles and strategies. A major cross department study could be conducted that includes teacher educators from different subject areas to see to how the implementation of formative assessment in the college varies from one department to another. A third possibility suggests a study involving student teachers from various areas of specialization in the college to see to what extent the implementation of formative assessment in the college affects their future assessment practices.
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An ion imprinted polymer for the determination of Ni (II) ions from mine tailing samples
- Authors: Rammika, Modise
- Date: 2011
- Subjects: Imprinted polymers , Metal ions , Polymerization , Mineral industries -- Waste disposal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4323 , http://hdl.handle.net/10962/d1004981 , Imprinted polymers , Metal ions , Polymerization , Mineral industries -- Waste disposal
- Description: A Ni(II)-dimethylglyoxime ion imprinted polymer {Ni(II)-DMG IIP} was synthesized by the trapping method using the bulk polymerisation format. The structures of the imprinted and non-imprinted polymer were evaluated by infrared spectroscopy and the morphology was observed by scanning electron microscopy. The Ni(II)-DMG IIP was optimised for pH, mass, time and by the uniform design experimental method for the molar ratios of monomer to crosslinker to porogen and template to ligands as well as keeping these parameters constant and varying the quantities of initiator, 2,2'-azobisisobutyronitrile (AIBN). The optimum pH was 8.5, optimum mass was 50 mg, optimum time was 1 min and the optimum molar ratios of crosslinker to monomer, monomer to template and nickel(II) sulfate hexahydrate (NiSO₄.6H₂O) to 4-vinylpyridine to dimethylglyoxime were found to be 3.3:1.0, 0.6:1.0 and 1.0:0.6:3.6 respectively with 30 mg and 8 mL as the optimum amounts of initiator and porogen respectively. Through this optimisation, recovery of Ni(II) was increased from 98 to 100%. Selectivity of the ion imprinted polymer was evaluated by analysing, using an inductively coupled plasma-optical emission spectrometer, for Ni(II) ions that were spiked with varying concentrations of Co(II), Cu(II), Zn(II), Pd(II), Fe(II), Ca(II), Mg(II), Na(I) and K(I) in aqueous samples. Selectivity studies also confirmed that the ion imprinted polymer had very good selectivity characterised by % RSD of less than 5 %. Co(II) was the only ion found to slightly interfere with the determination of Ni(II). The limits of detection and quantification were found to be 3x10⁻⁴ μg/mL and 9x10⁻⁴ μg/mL respectively. The method was evaluated by a custom solution of ground water certified reference material (SEP-3) and sandy soil reference material (BCR-142R) and the concentrations of Ni(II) obtained were not significantly different to the certified ones. The Ni(II)-DMG IIP was then evaluated in aqueous and soil samples where recoveries of 93 to 100% and 98 to 99% respectively were obtained with enrichment factors ranging from 2 to 18 in aqueous and 27 to 40 in soil samples. Finally, the Ni(II)-DMG IIP was used to analyse mine tailings samples and Ni(II) recovery of 99% was obtained with an enrichment factor of 2.
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- Authors: Rammika, Modise
- Date: 2011
- Subjects: Imprinted polymers , Metal ions , Polymerization , Mineral industries -- Waste disposal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4323 , http://hdl.handle.net/10962/d1004981 , Imprinted polymers , Metal ions , Polymerization , Mineral industries -- Waste disposal
- Description: A Ni(II)-dimethylglyoxime ion imprinted polymer {Ni(II)-DMG IIP} was synthesized by the trapping method using the bulk polymerisation format. The structures of the imprinted and non-imprinted polymer were evaluated by infrared spectroscopy and the morphology was observed by scanning electron microscopy. The Ni(II)-DMG IIP was optimised for pH, mass, time and by the uniform design experimental method for the molar ratios of monomer to crosslinker to porogen and template to ligands as well as keeping these parameters constant and varying the quantities of initiator, 2,2'-azobisisobutyronitrile (AIBN). The optimum pH was 8.5, optimum mass was 50 mg, optimum time was 1 min and the optimum molar ratios of crosslinker to monomer, monomer to template and nickel(II) sulfate hexahydrate (NiSO₄.6H₂O) to 4-vinylpyridine to dimethylglyoxime were found to be 3.3:1.0, 0.6:1.0 and 1.0:0.6:3.6 respectively with 30 mg and 8 mL as the optimum amounts of initiator and porogen respectively. Through this optimisation, recovery of Ni(II) was increased from 98 to 100%. Selectivity of the ion imprinted polymer was evaluated by analysing, using an inductively coupled plasma-optical emission spectrometer, for Ni(II) ions that were spiked with varying concentrations of Co(II), Cu(II), Zn(II), Pd(II), Fe(II), Ca(II), Mg(II), Na(I) and K(I) in aqueous samples. Selectivity studies also confirmed that the ion imprinted polymer had very good selectivity characterised by % RSD of less than 5 %. Co(II) was the only ion found to slightly interfere with the determination of Ni(II). The limits of detection and quantification were found to be 3x10⁻⁴ μg/mL and 9x10⁻⁴ μg/mL respectively. The method was evaluated by a custom solution of ground water certified reference material (SEP-3) and sandy soil reference material (BCR-142R) and the concentrations of Ni(II) obtained were not significantly different to the certified ones. The Ni(II)-DMG IIP was then evaluated in aqueous and soil samples where recoveries of 93 to 100% and 98 to 99% respectively were obtained with enrichment factors ranging from 2 to 18 in aqueous and 27 to 40 in soil samples. Finally, the Ni(II)-DMG IIP was used to analyse mine tailings samples and Ni(II) recovery of 99% was obtained with an enrichment factor of 2.
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An organisation development intervention in a secondary school in the Erongo region of Namibia
- Authors: Steenkamp, Angeline Anna
- Date: 2011
- Subjects: School management and organization -- Namibia -- Erongo Organizational change -- Namibia -- Erongo Curriculum planning -- Namibia -- Erongo
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1683 , http://hdl.handle.net/10962/d1003566
- Description: The challenge for Namibia is to translate Vision 2030 into realistic and implementable programmes and to develop and adopt a set of interventions which will raise the quality of education. The quality of education currently on offer varies from school to school and, indeed, from class to class (Namibia. MoE, 2006, p. 1). The National Standards and Performance Indicators (ETSIP, 2006) for schools in Namibia and the Education and Training Sector Improvement Programme (ETSIP), have been developed to address the quality of education across the country, and to make provision for school managers to be trained. Organisation Development is a planned change approach which focuses on the change processes of the organisation, by opening up communication, decreasing internal destructiveness – such as win-lose conflicts – and by increasing creativity in problem solving. It is based on the values and assumptions about people and their organisations. OD promotes interdependence and interconnectedness, involvement in problem solving and decision making. OD is a process for teaching people how to solve problems, take advantage of opportunities, and learn how to do better over time. OD was introduced to Evergreen Senior Secondary School in the form of a Survey Data Feedback (SDF) where data was collected, analysed and fed back to the participants. The case study involved 20 staff members made up of the principal, two head of departments and 17 teachers. Formal and focus-group interviews, as well as observation, were used to collect data. What was derived from the data was that the OD approach was something new to the participants, and served as an eye-opener. Further, it became evident from the data that participants had high hopes that OD would bring about immediate visible changes regarding the operation of their organisation. It is essential to remind participants that OD is a long-term change process, and not a “quick fix”.
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- Authors: Steenkamp, Angeline Anna
- Date: 2011
- Subjects: School management and organization -- Namibia -- Erongo Organizational change -- Namibia -- Erongo Curriculum planning -- Namibia -- Erongo
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1683 , http://hdl.handle.net/10962/d1003566
- Description: The challenge for Namibia is to translate Vision 2030 into realistic and implementable programmes and to develop and adopt a set of interventions which will raise the quality of education. The quality of education currently on offer varies from school to school and, indeed, from class to class (Namibia. MoE, 2006, p. 1). The National Standards and Performance Indicators (ETSIP, 2006) for schools in Namibia and the Education and Training Sector Improvement Programme (ETSIP), have been developed to address the quality of education across the country, and to make provision for school managers to be trained. Organisation Development is a planned change approach which focuses on the change processes of the organisation, by opening up communication, decreasing internal destructiveness – such as win-lose conflicts – and by increasing creativity in problem solving. It is based on the values and assumptions about people and their organisations. OD promotes interdependence and interconnectedness, involvement in problem solving and decision making. OD is a process for teaching people how to solve problems, take advantage of opportunities, and learn how to do better over time. OD was introduced to Evergreen Senior Secondary School in the form of a Survey Data Feedback (SDF) where data was collected, analysed and fed back to the participants. The case study involved 20 staff members made up of the principal, two head of departments and 17 teachers. Formal and focus-group interviews, as well as observation, were used to collect data. What was derived from the data was that the OD approach was something new to the participants, and served as an eye-opener. Further, it became evident from the data that participants had high hopes that OD would bring about immediate visible changes regarding the operation of their organisation. It is essential to remind participants that OD is a long-term change process, and not a “quick fix”.
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Analysis of volatility spillover effects between the South African, regional and world equity markets
- Authors: Mumba, Mabvuto
- Date: 2011
- Subjects: Financial crises International finance Stocks -- Prices -- Africa Stocks -- Prices -- South Africa Capital market -- Africa Capital market -- South Africa Foreign exchange rates Africa -- Economic conditions South Africa -- Economic conditions
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:957 , http://hdl.handle.net/10962/d1002691
- Description: The current study examines the extent and magnitude by which global and regional shocks are transmitted to the volatility of returns in the stock markets of South Africa, Egypt, Nigeria, Botswana, Mauritius and Egypt. This is done so as to make inferences on the level of the domestic market‟s integration into the regional and world capital markets. By applying multivariate and univariate GARCH models, using weekly data from June 1995 to May 2010, the main empirical findings are threefold. Firstly, the volatility analytical framework finds statistically significant and time-varying volatility spillover effects from the regional and global markets to the South African market. Global shocks are generally stronger and account for up to 23.9 percent of the volatility of South Africa‟s equity market compared to weaker regional factors which account for less than 1 percent of domestic variance. Only in countries with strong bilateral trade and economic links with South Africa, such as Botswana and Namibia, is it found that regional factors are more dominant than global factors for domestic volatility. Compared to the other African markets, the joint influence of foreign shocks on domestic volatility is highest in South Africa and Egypt, two of Africa‟s largest and most developed markets. The results further demonstrate that for all the African markets the explanatory power of both regional and global factors for domestic volatility is not constant over time and tends to increase during turbulent market periods. Secondly, the analysis of the determinants of South frica‟s second moment linkages with the global market suggests that the volatility of the exchange rate plays a cardinal role in influencing the magnitude by which global shocks affect domestic volatility. The increased global integration in the second moments cannot be attributed to either increased trade integration, convergence in inflation rates or to convergence in interest rates between South Africa and the global markets. Lastly, tests were conducted to examine whether there have been contagion effects from the regional and global markets to South Africa from the 1997 Asian crisis and the 2007/8 global financial crisis. The results show no evidence of contagion during either the East Asian currency crisis or the recent global financial crisis to South Africa, while some African markets, such as Egypt, Mauritius and Botswana, exhibit contagion effects from either crisis. Overall, the empirical findings generally support the view that African markets are segmented both at the regional and global levels as domestic volatility is more influenced by local idiosyncratic shocks (the proportion not attributable to either global and regional factors). However, the volatility of South Africa, and to a lesser extent Egypt, remains relatively more open to global influence. This implies that the potential for gains from international portfolio diversification and the scope for success of policies aimed at the stabilisation of equity markets in these markets exist.
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- Authors: Mumba, Mabvuto
- Date: 2011
- Subjects: Financial crises International finance Stocks -- Prices -- Africa Stocks -- Prices -- South Africa Capital market -- Africa Capital market -- South Africa Foreign exchange rates Africa -- Economic conditions South Africa -- Economic conditions
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:957 , http://hdl.handle.net/10962/d1002691
- Description: The current study examines the extent and magnitude by which global and regional shocks are transmitted to the volatility of returns in the stock markets of South Africa, Egypt, Nigeria, Botswana, Mauritius and Egypt. This is done so as to make inferences on the level of the domestic market‟s integration into the regional and world capital markets. By applying multivariate and univariate GARCH models, using weekly data from June 1995 to May 2010, the main empirical findings are threefold. Firstly, the volatility analytical framework finds statistically significant and time-varying volatility spillover effects from the regional and global markets to the South African market. Global shocks are generally stronger and account for up to 23.9 percent of the volatility of South Africa‟s equity market compared to weaker regional factors which account for less than 1 percent of domestic variance. Only in countries with strong bilateral trade and economic links with South Africa, such as Botswana and Namibia, is it found that regional factors are more dominant than global factors for domestic volatility. Compared to the other African markets, the joint influence of foreign shocks on domestic volatility is highest in South Africa and Egypt, two of Africa‟s largest and most developed markets. The results further demonstrate that for all the African markets the explanatory power of both regional and global factors for domestic volatility is not constant over time and tends to increase during turbulent market periods. Secondly, the analysis of the determinants of South frica‟s second moment linkages with the global market suggests that the volatility of the exchange rate plays a cardinal role in influencing the magnitude by which global shocks affect domestic volatility. The increased global integration in the second moments cannot be attributed to either increased trade integration, convergence in inflation rates or to convergence in interest rates between South Africa and the global markets. Lastly, tests were conducted to examine whether there have been contagion effects from the regional and global markets to South Africa from the 1997 Asian crisis and the 2007/8 global financial crisis. The results show no evidence of contagion during either the East Asian currency crisis or the recent global financial crisis to South Africa, while some African markets, such as Egypt, Mauritius and Botswana, exhibit contagion effects from either crisis. Overall, the empirical findings generally support the view that African markets are segmented both at the regional and global levels as domestic volatility is more influenced by local idiosyncratic shocks (the proportion not attributable to either global and regional factors). However, the volatility of South Africa, and to a lesser extent Egypt, remains relatively more open to global influence. This implies that the potential for gains from international portfolio diversification and the scope for success of policies aimed at the stabilisation of equity markets in these markets exist.
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Angel networks as a business start-up financing option in South Africa
- Authors: Sibanda, Zenzo
- Date: 2011
- Subjects: Angels (Investors) -- South Africa Small business -- Finance -- South Africa New business enterprises -- Finance -- South Africa Venture capital -- South Africa Microfinance -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1164 , http://hdl.handle.net/10962/d1002780
- Description: The following study is about business angels financing small business start-ups. It explores the aspect of starting up an entrepreneurial venture in which the entrepreneur seeks to secure start-up finance from lenders, raising the various issues that are known to characterise this engagement between the entrepreneur and the lender. Using the phenomenological paradigm, the study seeks to determine the awareness of small scale financing by entrepreneurs in South Africa, to determine the most commonly used source of start-up business funding in South Africa, to assess the extent to which business angel financing could be used to finance businesses in South Africa and to determine the factors impacting the use of business angel financing in South Africa. From these objectives, the study will also seek to determine the extent to which business angel networks could facilitate the financing of business start-ups. Small businesses invariably come up in different policy spheres as the main avenues to social and economic construction across national and regional lines. The importance of a successful business start up to a growing economy should not be underestimated. In line with this is the particular factor of gaining access to start up capital, which continues to emerge as a leading contributor to the success or failure of business start ups. Studies continue to verify that the most common challenge faced by most emerging entrepreneurs is start-up capital, either in the lack of this capital, the unfavourable conditions surrounding its availability, the lack of assets to serve as collateral for its use or the ambiguous flow of crucial information between lenders and providers of finance in the funding relationship (Abor and Biekpe, 2006: 69;Hernandez-Trillo, Pagan and Paxton, 2005: 435, ISPESE, 2005: 7, CDE, 2004: 5; Musengi 2003: 11). Roger Sorheim (2005: 179) refers to business angels as private individuals who offer risk capital to unlisted companies that are struggling to obtain start up capital to finance their business ideas. Business angels are further defined as high net-worth bearers of substantial private capital who predominantly invest in the early stage of high risk high potential return business ventures with a positive further growth potential. Business angel finance is typically a ‘once-off’ early stage form of small firm financing compared to the more frequent later stage venture capitalist funding. Studies show that business angels represent an underutilised wealth creation mechanism when it comes to small firm start-ups as most business angels contribute expertise in addition to finance to the start-ups they get involved in. This brings valuable business insight to the commercialisation of a good business idea. The business angel network exposes a range of potentially viable business prospects to willing investors by facilitating the flow of information about entrepreneurs and their businesses, thereby eliminating ambiguity, information asymmetry and transaction costs (Aernoudt and Erikson, 2002: 178; Van Osnabrugge and Robinson, 2000:374; Macht, 2006:1; Ehlrich, De Noble, Moore and Weaver, 1994:70; Sorheim, 2005:179). To achieve a holistic approach to a phenomenon which appears to be relatively new in South African business circles, the study will follow a qualitative approach in which two categories of populations will be used, one of small business operators and the other of business angels in South Africa. In the study, 20 small business operators and five business angels in Grahamstown will be approached using the convenience and snowballing sampling methods respectively. Face-to-face semi-structured interviews will be used as a data collection method and content analysis will be used as a data analysis tool (Collis and Hussey, 2003:156, Driver, Wood, Segal and Herrington, 2001:32, National Small Business Act ). There has been very limited research on business angels in the South African context, therefore the study would significantly contribute in entrepreneurship, government and small business development circles as it brings about attention to what the researcher predicts is an underutilised business start-up financing option.
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- Authors: Sibanda, Zenzo
- Date: 2011
- Subjects: Angels (Investors) -- South Africa Small business -- Finance -- South Africa New business enterprises -- Finance -- South Africa Venture capital -- South Africa Microfinance -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1164 , http://hdl.handle.net/10962/d1002780
- Description: The following study is about business angels financing small business start-ups. It explores the aspect of starting up an entrepreneurial venture in which the entrepreneur seeks to secure start-up finance from lenders, raising the various issues that are known to characterise this engagement between the entrepreneur and the lender. Using the phenomenological paradigm, the study seeks to determine the awareness of small scale financing by entrepreneurs in South Africa, to determine the most commonly used source of start-up business funding in South Africa, to assess the extent to which business angel financing could be used to finance businesses in South Africa and to determine the factors impacting the use of business angel financing in South Africa. From these objectives, the study will also seek to determine the extent to which business angel networks could facilitate the financing of business start-ups. Small businesses invariably come up in different policy spheres as the main avenues to social and economic construction across national and regional lines. The importance of a successful business start up to a growing economy should not be underestimated. In line with this is the particular factor of gaining access to start up capital, which continues to emerge as a leading contributor to the success or failure of business start ups. Studies continue to verify that the most common challenge faced by most emerging entrepreneurs is start-up capital, either in the lack of this capital, the unfavourable conditions surrounding its availability, the lack of assets to serve as collateral for its use or the ambiguous flow of crucial information between lenders and providers of finance in the funding relationship (Abor and Biekpe, 2006: 69;Hernandez-Trillo, Pagan and Paxton, 2005: 435, ISPESE, 2005: 7, CDE, 2004: 5; Musengi 2003: 11). Roger Sorheim (2005: 179) refers to business angels as private individuals who offer risk capital to unlisted companies that are struggling to obtain start up capital to finance their business ideas. Business angels are further defined as high net-worth bearers of substantial private capital who predominantly invest in the early stage of high risk high potential return business ventures with a positive further growth potential. Business angel finance is typically a ‘once-off’ early stage form of small firm financing compared to the more frequent later stage venture capitalist funding. Studies show that business angels represent an underutilised wealth creation mechanism when it comes to small firm start-ups as most business angels contribute expertise in addition to finance to the start-ups they get involved in. This brings valuable business insight to the commercialisation of a good business idea. The business angel network exposes a range of potentially viable business prospects to willing investors by facilitating the flow of information about entrepreneurs and their businesses, thereby eliminating ambiguity, information asymmetry and transaction costs (Aernoudt and Erikson, 2002: 178; Van Osnabrugge and Robinson, 2000:374; Macht, 2006:1; Ehlrich, De Noble, Moore and Weaver, 1994:70; Sorheim, 2005:179). To achieve a holistic approach to a phenomenon which appears to be relatively new in South African business circles, the study will follow a qualitative approach in which two categories of populations will be used, one of small business operators and the other of business angels in South Africa. In the study, 20 small business operators and five business angels in Grahamstown will be approached using the convenience and snowballing sampling methods respectively. Face-to-face semi-structured interviews will be used as a data collection method and content analysis will be used as a data analysis tool (Collis and Hussey, 2003:156, Driver, Wood, Segal and Herrington, 2001:32, National Small Business Act ). There has been very limited research on business angels in the South African context, therefore the study would significantly contribute in entrepreneurship, government and small business development circles as it brings about attention to what the researcher predicts is an underutilised business start-up financing option.
- Full Text:
Application of catalysts and nanomaterials in the design of an electrochemical sensor for ochratoxin A
- Authors: Flanagan, Shane Patrick
- Date: 2011 , 2010-12-06
- Subjects: Ochratoxins , Filamentous fungi , Electrochemical sensors , Nanostructured materials , Catalysts , Food contamination
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4121 , http://hdl.handle.net/10962/d1013328
- Description: Ochratoxin A is the most potent chlorinated derivative of the ochratoxin group, consisting of a 5'-chlorinated dihydroisocoumarin moiety linked by an amide bond to l-phenylalanine. Produced as a secondary fungal metabolite by several species of Aspergillus and Penicillium, ochratoxin A has been shown to readily contaminate a large variety of commodities including cereals, groundnuts, dried fruit, spices and coffee. This has led to widespread contamination of ochratoxin in wine, beer, milk and meat products. As ochratoxin A is a potent nephrotoxin exhibiting teratogenic and carcinogenic properties, the development of a rapid screening platform for the cost effective control of ochratoxin A content in foodstuffs is therefore required. The evaluation of metallophthalocyanine and carbon nanotube electrode modification toward the development of a nanostructured biosensor capable of enhancing the electrochemical detection of ochratoxin A in complex media is presented. Cyclic voltammetry at a glassy carbon electrode allowed for the optimization of detection parameters including pH and type of supporting electrolyte. Britton-Robinson buffer was found to be the most suitable supporting electrolyte in terms of sensitivity and reproducibility obtaining a LOD of 0.28 μM as determined by differential pulse voltammetry. Subsequent analysis determined the dependence of OTA oxidation on pH in acidic media which proceeds with the transfer of two electrons to form a quinone/hydroquinone couple shown to adsorb to the electrode surface. Passivation of the electrode through adsorption of oxidation products was shown to severely limit the detection of OTA upon successive detection cycles. Comparison of various metallophthalocyanine modifiers showed an increase in sensitivity toward the detection of OTA at phthalocyanine complexes with metal based redox processes. However with the exception of NiPc and CoTCPc complexes, phthalocyanine modification was limited by the increase in deviation of current response and extent of fouling. NiPc modification showed an increase in sensitivity by two fold with fouling characteristics comparable to an unmodified electrode while low improvements in fouling was observed at CoTCPc modified electrodes with sensitivity in detection comparable to an unmodified electrode.Modification of the electrode with multi- and single walled carbon nanotubes produced a significant increase in sensitivity toward the detection of ochratoxin A. The electrocatalytic activity of nanotube modifiers was attributed to the increase in surface area and to the addition of oxygenated functional groups upon acid treatment as confirmed by Raman spectroscopy. Acid functionalization of the carbon nanotubes for a period of two hours produced the greatest increase in sensitivity obtaining a respective LOD of 0.09 μM and 0.03 μM for analysis of ochratoxin A at multi- and single walled carbon nanotube modified electrodes. Centrifugal purification of carbon nanotubes was deemed necessary to improve the electrocatalytic activity of the nanotube modifiers through the removal of carbonaceous impurities as visualized by atomic force microscopy. Furthermore, a crude lipase preparation, lipase A, was investigated as a potential biological recognition element for selective detection of ochratoxin A in complex media. Lipase A enabled the hydrolysis of ochratoxin A to the electroactive species ochratoxin α as confirmed by thin layer chromatography and voltammetric analysis. Additional isolation of a pure hydrolase from the lipase A preparation is required prior to utilization within a nanostructured biosensor platform capable of detecting ochratoxin A in complex media.
- Full Text:
- Authors: Flanagan, Shane Patrick
- Date: 2011 , 2010-12-06
- Subjects: Ochratoxins , Filamentous fungi , Electrochemical sensors , Nanostructured materials , Catalysts , Food contamination
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4121 , http://hdl.handle.net/10962/d1013328
- Description: Ochratoxin A is the most potent chlorinated derivative of the ochratoxin group, consisting of a 5'-chlorinated dihydroisocoumarin moiety linked by an amide bond to l-phenylalanine. Produced as a secondary fungal metabolite by several species of Aspergillus and Penicillium, ochratoxin A has been shown to readily contaminate a large variety of commodities including cereals, groundnuts, dried fruit, spices and coffee. This has led to widespread contamination of ochratoxin in wine, beer, milk and meat products. As ochratoxin A is a potent nephrotoxin exhibiting teratogenic and carcinogenic properties, the development of a rapid screening platform for the cost effective control of ochratoxin A content in foodstuffs is therefore required. The evaluation of metallophthalocyanine and carbon nanotube electrode modification toward the development of a nanostructured biosensor capable of enhancing the electrochemical detection of ochratoxin A in complex media is presented. Cyclic voltammetry at a glassy carbon electrode allowed for the optimization of detection parameters including pH and type of supporting electrolyte. Britton-Robinson buffer was found to be the most suitable supporting electrolyte in terms of sensitivity and reproducibility obtaining a LOD of 0.28 μM as determined by differential pulse voltammetry. Subsequent analysis determined the dependence of OTA oxidation on pH in acidic media which proceeds with the transfer of two electrons to form a quinone/hydroquinone couple shown to adsorb to the electrode surface. Passivation of the electrode through adsorption of oxidation products was shown to severely limit the detection of OTA upon successive detection cycles. Comparison of various metallophthalocyanine modifiers showed an increase in sensitivity toward the detection of OTA at phthalocyanine complexes with metal based redox processes. However with the exception of NiPc and CoTCPc complexes, phthalocyanine modification was limited by the increase in deviation of current response and extent of fouling. NiPc modification showed an increase in sensitivity by two fold with fouling characteristics comparable to an unmodified electrode while low improvements in fouling was observed at CoTCPc modified electrodes with sensitivity in detection comparable to an unmodified electrode.Modification of the electrode with multi- and single walled carbon nanotubes produced a significant increase in sensitivity toward the detection of ochratoxin A. The electrocatalytic activity of nanotube modifiers was attributed to the increase in surface area and to the addition of oxygenated functional groups upon acid treatment as confirmed by Raman spectroscopy. Acid functionalization of the carbon nanotubes for a period of two hours produced the greatest increase in sensitivity obtaining a respective LOD of 0.09 μM and 0.03 μM for analysis of ochratoxin A at multi- and single walled carbon nanotube modified electrodes. Centrifugal purification of carbon nanotubes was deemed necessary to improve the electrocatalytic activity of the nanotube modifiers through the removal of carbonaceous impurities as visualized by atomic force microscopy. Furthermore, a crude lipase preparation, lipase A, was investigated as a potential biological recognition element for selective detection of ochratoxin A in complex media. Lipase A enabled the hydrolysis of ochratoxin A to the electroactive species ochratoxin α as confirmed by thin layer chromatography and voltammetric analysis. Additional isolation of a pure hydrolase from the lipase A preparation is required prior to utilization within a nanostructured biosensor platform capable of detecting ochratoxin A in complex media.
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Application of macroinvertebrate based biomonitoring approaches to assess anthropogenic impacts in the Swartkops River, South Africa
- Authors: Odume, Oghenekaro Nelson
- Date: 2011
- Subjects: Water -- Pollution -- South Africa -- Swartkops River Water quality biological assessment -- South Africa -- Swartkops River Environmental monitoring -- South Africa -- Swartkops River Aquatic invertebrates -- Effect of water pollution on -- South Africa -- Swartkops River
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:6040 , http://hdl.handle.net/10962/d1006199
- Description: A growing human population accompanied by urbanisation and industrialisation have led to over exploitation and pollution of freshwater resources and have consequently impacted on aquatic ecosystem health. The Swartkops River in the Eastern Cape of South Africa is no exception. It drains a heavily industrialised catchment which has led to deterioration of its water quality due to pollution. Integrated water resources management (IWRM) requires the concurrent sustainable use of water resources and the protection of aquatic ecosystem health. Macroinvertebrates are well known for their ability to reflect the health of the environment in which they live, thus they were used to assess anthropogenic impacts in the Swartkops River for this study. Macroinvertebrate based biomonitoring approaches, including the South African Scoring System version 5 (SASS5); a multimetric approach involving 19 metrics; Chironomidae community assessments and screening of morphological deformities in Chironomidae larvae, were applied at four selected sampling sites to assess environmental water quality in the Swartkops River. Macroinvertebrates were sampled us ing the SASS5 protocols. Chironomidae were mounted and identified as far as practically possible using available keys. Mentum, ligula, mandible, paraligula and antenna in Chironomidae larvae were screened for deformities. Physical and chemical water quality variables were measured at each of the selected sampling sites. All data were subjected to relevant statistical analyses. Of the four sites sampled during the study period, results revealed that water quality at site 1 was the least impacted with highest SASS5 scores, average score per taxa (ASPT) values, richness, diversity, equitability and Ephemeroptera –Plecoptera-Trichoptera (EPT) richness, as well as least incidences of chironomid deformities. Water quality at site 2 was considered the next least impacted with higher SASS5 scores, A SPT values, richness, diversity and equitability, and lower incidences of deformities compared to sites 3 and 4. SASS5 scores and ASPT values revealed that both sites 3 and 4 were critically modified but the multimetric analysis, Chironomidae community assessment and incidences of deformities in Chironomidae larvae indicated that site 3 is the most impacted of the four sampling sites, with least species diversity, richness, equitability and highest incidences of deformities. The study revealed the importance of multicriteria approach to environmental biomonitoring as an integrated water resources management tool, and based on the results, site 3, as the most impacted, could be prioritised for restoration intervention.
- Full Text:
- Authors: Odume, Oghenekaro Nelson
- Date: 2011
- Subjects: Water -- Pollution -- South Africa -- Swartkops River Water quality biological assessment -- South Africa -- Swartkops River Environmental monitoring -- South Africa -- Swartkops River Aquatic invertebrates -- Effect of water pollution on -- South Africa -- Swartkops River
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:6040 , http://hdl.handle.net/10962/d1006199
- Description: A growing human population accompanied by urbanisation and industrialisation have led to over exploitation and pollution of freshwater resources and have consequently impacted on aquatic ecosystem health. The Swartkops River in the Eastern Cape of South Africa is no exception. It drains a heavily industrialised catchment which has led to deterioration of its water quality due to pollution. Integrated water resources management (IWRM) requires the concurrent sustainable use of water resources and the protection of aquatic ecosystem health. Macroinvertebrates are well known for their ability to reflect the health of the environment in which they live, thus they were used to assess anthropogenic impacts in the Swartkops River for this study. Macroinvertebrate based biomonitoring approaches, including the South African Scoring System version 5 (SASS5); a multimetric approach involving 19 metrics; Chironomidae community assessments and screening of morphological deformities in Chironomidae larvae, were applied at four selected sampling sites to assess environmental water quality in the Swartkops River. Macroinvertebrates were sampled us ing the SASS5 protocols. Chironomidae were mounted and identified as far as practically possible using available keys. Mentum, ligula, mandible, paraligula and antenna in Chironomidae larvae were screened for deformities. Physical and chemical water quality variables were measured at each of the selected sampling sites. All data were subjected to relevant statistical analyses. Of the four sites sampled during the study period, results revealed that water quality at site 1 was the least impacted with highest SASS5 scores, average score per taxa (ASPT) values, richness, diversity, equitability and Ephemeroptera –Plecoptera-Trichoptera (EPT) richness, as well as least incidences of chironomid deformities. Water quality at site 2 was considered the next least impacted with higher SASS5 scores, A SPT values, richness, diversity and equitability, and lower incidences of deformities compared to sites 3 and 4. SASS5 scores and ASPT values revealed that both sites 3 and 4 were critically modified but the multimetric analysis, Chironomidae community assessment and incidences of deformities in Chironomidae larvae indicated that site 3 is the most impacted of the four sampling sites, with least species diversity, richness, equitability and highest incidences of deformities. The study revealed the importance of multicriteria approach to environmental biomonitoring as an integrated water resources management tool, and based on the results, site 3, as the most impacted, could be prioritised for restoration intervention.
- Full Text:
Assessment of organochlorine pesticide residues in fish samples from the Okavango Delta, Botswana
- Authors: Mpofu, Christopher
- Date: 2011 , 2011-02-28
- Subjects: Pesticides , Organochlorine compounds , Freshwater fishes -- Effect of pesticides on -- Botswana -- Okavango River Delta , Water -- Pesticide content -- Botswana -- Okavango River Delta , Catfishes -- Botswana -- Okavango River Delta , Tigerfish -- Botswana -- Okavango River Delta , Redbreast tilapia -- Botswana -- Okavango River Delta
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4404 , http://hdl.handle.net/10962/d1006707 , Pesticides , Organochlorine compounds , Freshwater fishes -- Effect of pesticides on -- Botswana -- Okavango River Delta , Water -- Pesticide content -- Botswana -- Okavango River Delta , Catfishes -- Botswana -- Okavango River Delta , Tigerfish -- Botswana -- Okavango River Delta , Redbreast tilapia -- Botswana -- Okavango River Delta
- Description: This thesis presents an evaluation of the dispersive solid-phase extraction (d-SPE) method referred to as the quick, easy, cheap, effective, rugged and safe (QuEChERS) method for the determination of four organochlorine pesticide residues in fish samples. The pesticides investigated in this study were o, p′-DDT, p, p′-DDE, aldrin and dieldrin. The combined use of Gas Chromatography with an Electron Capture Detector (GC-ECD) and sensitive Time of Flight (TOF) mass detector facilitated the identification of the target analytes. In the absence of certified reference material, the overall analytical procedure was validated by systematic recovery experiments on spiked samples at three levels of 2, 5 and 10 ng/g. The targeted compounds were successfully extracted and their recovery ranged from 76 to 96% with relative standard deviations of less than 13%. The optimum QuEChERS conditions were 2g of fish powder, 10 ml acetonitrile and 1 min shaking time. The optimal conditions were applied to assess the levels of chlorinated pesticides in blunt-tooth catfish (Clarias ngamensis), tigerfish (Hydrocynus vittatus), Oreochromis andersonii and red-breasted tilapia (Tilapia rendalli) from the Okavango Delta, Botswana. Dieldrin, p, p′-DDE and aldrin were detected in all the analysed samples with a concentration range of 0.04 – 0.29, 0.07 – 0.33, 0.04 – 0.28 and 0.03 – 0.24 ng/g per dry weight in O. andersonii, C. ngamensis, T. rendalli and H. vittatus respectively. These concentrations were below the US-EPA 0.1 μg/g allowable limit in edible fish and the Australian Maximum Residue Limit (MRL) of 50 - 1000 ng/g in fresh fish. DDT was not detected in all the fish species investigated. The mean lipid content recorded in the fish samples were 1.24, 2.16, 2.18 and 4.21% for H. vittatus, T. rendalli, O. andersonni and C. ngamensis respectively. No systematic trend was observed between fish age and pesticide levels in fish. Acetylcholinesterase (AChE) activity assays were performed to assess the effects of organochlorine pesticides in Clarias ngamensis. The enzyme activity recorded in Clarias ngamensis from the Okavango Delta and the reference site was 12.31 μmol of acetylcholine iodide hydrolysed/min/g brain tissue. The enzyme activity remained the same indicating no enzyme inhibition. The conclusions drawn from this study are that the QuEChERS method is applicable for the determination of organochlorine pesticide residues in fish matrices. The fish from the Okavango Delta are safe for human consumption.
- Full Text:
- Authors: Mpofu, Christopher
- Date: 2011 , 2011-02-28
- Subjects: Pesticides , Organochlorine compounds , Freshwater fishes -- Effect of pesticides on -- Botswana -- Okavango River Delta , Water -- Pesticide content -- Botswana -- Okavango River Delta , Catfishes -- Botswana -- Okavango River Delta , Tigerfish -- Botswana -- Okavango River Delta , Redbreast tilapia -- Botswana -- Okavango River Delta
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4404 , http://hdl.handle.net/10962/d1006707 , Pesticides , Organochlorine compounds , Freshwater fishes -- Effect of pesticides on -- Botswana -- Okavango River Delta , Water -- Pesticide content -- Botswana -- Okavango River Delta , Catfishes -- Botswana -- Okavango River Delta , Tigerfish -- Botswana -- Okavango River Delta , Redbreast tilapia -- Botswana -- Okavango River Delta
- Description: This thesis presents an evaluation of the dispersive solid-phase extraction (d-SPE) method referred to as the quick, easy, cheap, effective, rugged and safe (QuEChERS) method for the determination of four organochlorine pesticide residues in fish samples. The pesticides investigated in this study were o, p′-DDT, p, p′-DDE, aldrin and dieldrin. The combined use of Gas Chromatography with an Electron Capture Detector (GC-ECD) and sensitive Time of Flight (TOF) mass detector facilitated the identification of the target analytes. In the absence of certified reference material, the overall analytical procedure was validated by systematic recovery experiments on spiked samples at three levels of 2, 5 and 10 ng/g. The targeted compounds were successfully extracted and their recovery ranged from 76 to 96% with relative standard deviations of less than 13%. The optimum QuEChERS conditions were 2g of fish powder, 10 ml acetonitrile and 1 min shaking time. The optimal conditions were applied to assess the levels of chlorinated pesticides in blunt-tooth catfish (Clarias ngamensis), tigerfish (Hydrocynus vittatus), Oreochromis andersonii and red-breasted tilapia (Tilapia rendalli) from the Okavango Delta, Botswana. Dieldrin, p, p′-DDE and aldrin were detected in all the analysed samples with a concentration range of 0.04 – 0.29, 0.07 – 0.33, 0.04 – 0.28 and 0.03 – 0.24 ng/g per dry weight in O. andersonii, C. ngamensis, T. rendalli and H. vittatus respectively. These concentrations were below the US-EPA 0.1 μg/g allowable limit in edible fish and the Australian Maximum Residue Limit (MRL) of 50 - 1000 ng/g in fresh fish. DDT was not detected in all the fish species investigated. The mean lipid content recorded in the fish samples were 1.24, 2.16, 2.18 and 4.21% for H. vittatus, T. rendalli, O. andersonni and C. ngamensis respectively. No systematic trend was observed between fish age and pesticide levels in fish. Acetylcholinesterase (AChE) activity assays were performed to assess the effects of organochlorine pesticides in Clarias ngamensis. The enzyme activity recorded in Clarias ngamensis from the Okavango Delta and the reference site was 12.31 μmol of acetylcholine iodide hydrolysed/min/g brain tissue. The enzyme activity remained the same indicating no enzyme inhibition. The conclusions drawn from this study are that the QuEChERS method is applicable for the determination of organochlorine pesticide residues in fish matrices. The fish from the Okavango Delta are safe for human consumption.
- Full Text:
Associations in ephemeral systems: the lack of trophic relationships between sandhoppers and beach wrack
- Porri, Francesca, Hill, Jaclyn M, McQuaid, Christopher D
- Authors: Porri, Francesca , Hill, Jaclyn M , McQuaid, Christopher D
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444552 , vital:74250 , https://doi.org/10.3354/meps08951
- Description: In ephemeral systems, material subsidies can play a key role in the persistence and connectivity of populations, especially if the organisms living within them are trophically dependent on imported resources. Sandy beaches are heavily subsidized by organic material of both terrestrial and marine origin. For highly mobile supratidal fringe species, such as amphipods, which are marine but with a high tolerance of aerial conditions, such material potentially provides both food and shelter. We investigated the relationship between beach wrack and amphipods by examining the trophic contribution of allochthonous food sources to sandhopper diets using stable isotope analysis. Replicate samples of the sandhopper Talorchestia capensis and several types of beach wrack (including seagrass, wood and different macrophytes) colonized by these amphipods were collected from 11 sites within one biogeographical region along the south coast of South Africa.
- Full Text:
- Authors: Porri, Francesca , Hill, Jaclyn M , McQuaid, Christopher D
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444552 , vital:74250 , https://doi.org/10.3354/meps08951
- Description: In ephemeral systems, material subsidies can play a key role in the persistence and connectivity of populations, especially if the organisms living within them are trophically dependent on imported resources. Sandy beaches are heavily subsidized by organic material of both terrestrial and marine origin. For highly mobile supratidal fringe species, such as amphipods, which are marine but with a high tolerance of aerial conditions, such material potentially provides both food and shelter. We investigated the relationship between beach wrack and amphipods by examining the trophic contribution of allochthonous food sources to sandhopper diets using stable isotope analysis. Replicate samples of the sandhopper Talorchestia capensis and several types of beach wrack (including seagrass, wood and different macrophytes) colonized by these amphipods were collected from 11 sites within one biogeographical region along the south coast of South Africa.
- Full Text:
Bayesian logistic regression models for credit scoring
- Authors: Webster, Gregg
- Date: 2011
- Subjects: Bayesian statistical decision theory Credit scoring systems Regression analysis Logistic regression analysis Monte Carlo method Markov processes Financial institutions
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:5574 , http://hdl.handle.net/10962/d1005538
- Description: The Bayesian approach to logistic regression modelling for credit scoring is useful when there are data quantity issues. Data quantity issues might occur when a bank is opening in a new location or there is change in the scoring procedure. Making use of prior information (available from the coefficients estimated on other data sets, or expert knowledge about the coefficients) a Bayesian approach is proposed to improve the credit scoring models. To achieve this, a data set is split into two sets, “old” data and “new” data. Priors are obtained from a model fitted on the “old” data. This model is assumed to be a scoring model used by a financial institution in the current location. The financial institution is then assumed to expand into a new economic location where there is limited data. The priors from the model on the “old” data are then combined in a Bayesian model with the “new” data to obtain a model which represents all the available information. The predictive performance of this Bayesian model is compared to a model which does not make use of any prior information. It is found that the use of relevant prior information improves the predictive performance when the size of the “new” data is small. As the size of the “new” data increases, the importance of including prior information decreases
- Full Text:
- Authors: Webster, Gregg
- Date: 2011
- Subjects: Bayesian statistical decision theory Credit scoring systems Regression analysis Logistic regression analysis Monte Carlo method Markov processes Financial institutions
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:5574 , http://hdl.handle.net/10962/d1005538
- Description: The Bayesian approach to logistic regression modelling for credit scoring is useful when there are data quantity issues. Data quantity issues might occur when a bank is opening in a new location or there is change in the scoring procedure. Making use of prior information (available from the coefficients estimated on other data sets, or expert knowledge about the coefficients) a Bayesian approach is proposed to improve the credit scoring models. To achieve this, a data set is split into two sets, “old” data and “new” data. Priors are obtained from a model fitted on the “old” data. This model is assumed to be a scoring model used by a financial institution in the current location. The financial institution is then assumed to expand into a new economic location where there is limited data. The priors from the model on the “old” data are then combined in a Bayesian model with the “new” data to obtain a model which represents all the available information. The predictive performance of this Bayesian model is compared to a model which does not make use of any prior information. It is found that the use of relevant prior information improves the predictive performance when the size of the “new” data is small. As the size of the “new” data increases, the importance of including prior information decreases
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Becoming African: debating post-apartheid white South African identities
- Authors: Matthews, Sally
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142409 , vital:38077 , DOI: 10.1080/14725843.2011.530440
- Description: The post-apartheid era necessitates the rethinking of white identities in South Africa. One way in which some white South Africans are seeking to redefine themselves is through describing themselves as African. However, claims by white South Africans that they too are Africans have been met with mixed responses from black South Africans. In this article I use contributions to an online university students' forum to explore ways in which some white South Africans are embracing an African identity and to consider ways in which some black South Africans are responding to white South Africans' shifting identities. I use contributions to this forum as a starting point to think about the possibilities and limitations that the embracing of an African identity has for the development of what Frankenberg calls ‘anti-racist forms of whiteness’ among white South Africans.
- Full Text:
- Authors: Matthews, Sally
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142409 , vital:38077 , DOI: 10.1080/14725843.2011.530440
- Description: The post-apartheid era necessitates the rethinking of white identities in South Africa. One way in which some white South Africans are seeking to redefine themselves is through describing themselves as African. However, claims by white South Africans that they too are Africans have been met with mixed responses from black South Africans. In this article I use contributions to an online university students' forum to explore ways in which some white South Africans are embracing an African identity and to consider ways in which some black South Africans are responding to white South Africans' shifting identities. I use contributions to this forum as a starting point to think about the possibilities and limitations that the embracing of an African identity has for the development of what Frankenberg calls ‘anti-racist forms of whiteness’ among white South Africans.
- Full Text:
Being Indian, being MK: an exploration of the experiences and ethnic identities of Indian South African Umkhonto we Sizwe members
- Authors: Lalla, Varsha
- Date: 2011
- Subjects: Umkhonto we Sizwe (South Africa) -- Research Political activists -- Research -- South Africa East Indians -- Politics and government -- Research -- South Africa Ethnicity -- Political aspects -- South Africa -- Research
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2792 , http://hdl.handle.net/10962/d1003002
- Description: Umkhonto we Sizwe (MK) was a military organization dominated by black Africans. Although it is not generally associated with Indian South Africans, who form a minority in the country, there were Indian MK members. This thesis explores the way in which Indian MK members reconciled aspects of their ethnic identity with their membership of MK. It explores the experiences of two generations of members: those born between 1929 and 1944 and those born between 1960 and 1969. In particular it looks at whether they experienced tensions between their ethnic and political identities. It explores what set these Indian South Africans apart from the rest of the Indian South African community that did not join MK. It also looks at what significant differences there were between different generations of Indian MK members. The research results show that the first generation MK members believe that their MK activities were „the highest form of passive resistance‟. An explanation for this way of referring to their activities could be that this was a way of reconciling tensions between their ethnic and political identities. The first generation was also very critical of the Indian SA community. This could be because they still feel part of this community despite having a strong political consciousness that is different from most of the community. It was found that some of the features that set Indian MK members apart from other Indian South Africans were that they were not raised in very religious households and occupied a fairly low rather than „middle man‟ economic position. In addition, members of the first generation of MK members were raised in comparatively multi-racial areas. Both generations made the decision to join MK because of Indian role models. There were some marked differences between the two generations of MK veterans. Most notably, the younger did not see their activities as in line with passive resistance and they also displayed more ambivalence about their ethnic identities.
- Full Text:
- Authors: Lalla, Varsha
- Date: 2011
- Subjects: Umkhonto we Sizwe (South Africa) -- Research Political activists -- Research -- South Africa East Indians -- Politics and government -- Research -- South Africa Ethnicity -- Political aspects -- South Africa -- Research
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2792 , http://hdl.handle.net/10962/d1003002
- Description: Umkhonto we Sizwe (MK) was a military organization dominated by black Africans. Although it is not generally associated with Indian South Africans, who form a minority in the country, there were Indian MK members. This thesis explores the way in which Indian MK members reconciled aspects of their ethnic identity with their membership of MK. It explores the experiences of two generations of members: those born between 1929 and 1944 and those born between 1960 and 1969. In particular it looks at whether they experienced tensions between their ethnic and political identities. It explores what set these Indian South Africans apart from the rest of the Indian South African community that did not join MK. It also looks at what significant differences there were between different generations of Indian MK members. The research results show that the first generation MK members believe that their MK activities were „the highest form of passive resistance‟. An explanation for this way of referring to their activities could be that this was a way of reconciling tensions between their ethnic and political identities. The first generation was also very critical of the Indian SA community. This could be because they still feel part of this community despite having a strong political consciousness that is different from most of the community. It was found that some of the features that set Indian MK members apart from other Indian South Africans were that they were not raised in very religious households and occupied a fairly low rather than „middle man‟ economic position. In addition, members of the first generation of MK members were raised in comparatively multi-racial areas. Both generations made the decision to join MK because of Indian role models. There were some marked differences between the two generations of MK veterans. Most notably, the younger did not see their activities as in line with passive resistance and they also displayed more ambivalence about their ethnic identities.
- Full Text:
Being moved by a way the world is not
- Authors: Jones, Ward E
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275631 , vital:55064 , xlink:href="https://doi.org/10.1007/s11229-009-9522-z"
- Description: At the end of Lecture 3 of The Empirical Stance, Bas van Fraassen suggests that we see the change of view involved in scientific revolutions as being, at least in part, emotional. In this paper, I explore one plausible way of cashing out this suggestion. Someone’s emotional approval of a description of the world, I argue, thereby shows that she takes herself to have reason to take that description seriously. This is true even if she is convinced—as a scientific community is when it considers alternative theories—that this description is false, that it is not the way the world is.
- Full Text:
- Authors: Jones, Ward E
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275631 , vital:55064 , xlink:href="https://doi.org/10.1007/s11229-009-9522-z"
- Description: At the end of Lecture 3 of The Empirical Stance, Bas van Fraassen suggests that we see the change of view involved in scientific revolutions as being, at least in part, emotional. In this paper, I explore one plausible way of cashing out this suggestion. Someone’s emotional approval of a description of the world, I argue, thereby shows that she takes herself to have reason to take that description seriously. This is true even if she is convinced—as a scientific community is when it considers alternative theories—that this description is false, that it is not the way the world is.
- Full Text:
Biological control of cactaceae in South Africa
- Paterson, Iain D, Hoffmann, John H, Klein, Hildegard, Mathenge, C W, Neser, Stephan, Zimmermann, Helmuth G
- Authors: Paterson, Iain D , Hoffmann, John H , Klein, Hildegard , Mathenge, C W , Neser, Stephan , Zimmermann, Helmuth G
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452308 , vital:75119 , https://hdl.handle.net/10520/EJC32918
- Description: This review is a summary of developments that have contributed to the success of several biological control programmes against invasive cactus species (Cactaceae) that have been worked on in South Africa over the last 12 years. Six potential biological control agents have been identified for the control of Pereskia aculeata Mill. and molecular studies have identified the origin of the South African P. aculeata population. Host-specificity testing is now required for the three most promising of these agents. The successful biological control programme against Opuntia stricta (Haw.) Haw. has resulted in a change in management strategies against this weed in the Kruger National Park and the control of O. stricta is now almost entirely reliant on biological control. Taxonomic problems associated with the identification of Cylindropuntia fulgida var. fulgida (Engelm.) F.M.Knuth var. fulgida have been resolved and an appropriate cochineal insect (Hemiptera: Dactylopiidae) biotype has been released, resulting in substantial declines in Cyl. fulgida var. fulgida populations. A long-term monitoring programme has been initiated to evaluate the progress of this new cochineal insect biotype. The Harrisia mealybug, Hypogeococcus pungens Granara de Willink (Hemiptera: Pseudococcidae), which was originally released on Harrisia martinii (Labour.) Britton and Rose has been collected and redistributed onto Cereus jamacaru DC., where it reduces fruit production and leads to the death of both seedlings and large plants. Resolving taxonomic problems to ensure the correct identification of plant species and the most appropriate biological control biotypes have been key issues that have led to the successful control of several cactaceous weed species in South Africa.
- Full Text:
- Authors: Paterson, Iain D , Hoffmann, John H , Klein, Hildegard , Mathenge, C W , Neser, Stephan , Zimmermann, Helmuth G
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452308 , vital:75119 , https://hdl.handle.net/10520/EJC32918
- Description: This review is a summary of developments that have contributed to the success of several biological control programmes against invasive cactus species (Cactaceae) that have been worked on in South Africa over the last 12 years. Six potential biological control agents have been identified for the control of Pereskia aculeata Mill. and molecular studies have identified the origin of the South African P. aculeata population. Host-specificity testing is now required for the three most promising of these agents. The successful biological control programme against Opuntia stricta (Haw.) Haw. has resulted in a change in management strategies against this weed in the Kruger National Park and the control of O. stricta is now almost entirely reliant on biological control. Taxonomic problems associated with the identification of Cylindropuntia fulgida var. fulgida (Engelm.) F.M.Knuth var. fulgida have been resolved and an appropriate cochineal insect (Hemiptera: Dactylopiidae) biotype has been released, resulting in substantial declines in Cyl. fulgida var. fulgida populations. A long-term monitoring programme has been initiated to evaluate the progress of this new cochineal insect biotype. The Harrisia mealybug, Hypogeococcus pungens Granara de Willink (Hemiptera: Pseudococcidae), which was originally released on Harrisia martinii (Labour.) Britton and Rose has been collected and redistributed onto Cereus jamacaru DC., where it reduces fruit production and leads to the death of both seedlings and large plants. Resolving taxonomic problems to ensure the correct identification of plant species and the most appropriate biological control biotypes have been key issues that have led to the successful control of several cactaceous weed species in South Africa.
- Full Text:
Biological control of Pereskia aculeata Miller (Cactaceae)
- Authors: Paterson, Iain Douglas
- Date: 2011
- Subjects: Pereskia -- Biological control -- South Africa Cactus -- Biological control -- South Africa Invasive plants -- Biological control -- South Africa Curculionidae -- South Africa Pyralidae -- South Africa Insects as biological pest control agents -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5825 , http://hdl.handle.net/10962/d1007653
- Description: Pereskia aculeata Miller (Cactaceae) is an environmental weed that is damaging to natural ecosystems in South Africa. The plant is native to Central and South America and was first recorded in South Africa in a botanical garden in 1858. In this thesis, research into the biological control of P. aculeata was conducted with the intention of improving the control of the weed. A pre-release study of the relationship between P. aculeata density and native plant biodiversity indicated that P. aculeata has a negative impact on native biodiversity. The native plant biodiversity associated with different P. aculeata densities was used to determine threshold values and goals for the control of the weed. A threshold value of 50% P. aculeata density was calculated, indicating that P. aculeata density must be maintained below 50% in order to conserve native plant biodiversity. The ultimate goal of the control programme should be to maintain P. aculeata densities below 30%. At these densities there was no significant difference in native plant biodiversity from if the weed were absent from the ecosystem. The biological control agent, Phenrica guérini Bechyne (Chrysomelidae), has been released in South Africa but the potential of the agent to impact P. aculeata is not known and no post release evaluation has been conducted. Impact assessment studies indicate that P. guérini does not impact P. aculeata, even at high densities, but the results of greenhouse experiments should be interpreted with caution because of problems with extrapolation into the field. Although observations in the field suggest that P. guérini has reduced P. aculeata densities at one site, it is clear that new biological control agents are needed to reduce the weed to acceptable levels. Identifying the origin of the South African P. aculeata population was believed to be important to the biological control programme due to the disjunct native distribution and intraspecific variation of the species. Natural enemies associated with plant genotypes in different parts of the native distribution may have developed specialised relationships with certain intraspecific variants of the plant, resulting in differences in agent efficacy on certain host plant genotypes. A molecular study indicated that the closest relatives to the South African weed population found in the native distribution were in Rio de Janeiro Province, Brazil. A bioassay experiment in which fitness related traits of the biological control agent, P. guérini, were measured on various P. aculeata genotypes was conducted to determine the importance of host plant intraspecific variation. There was little variation in fitness traits between genotypes and no evidence of intraspecific host plant specialization. Although intraspecific variation had no effect on agent efficacy in the case of P. guérini, it is possible that other natural enemies may be more specialized. Genotype matching is expected to be more important when natural enemies likely to be specialised to individual genotypes are considered for biological control. Potential biological control agents were prioritized from data collected on surveys in the native distribution. The most promising of these, based on the presence of feeding, incidence, predicted host range, climatic matching, genotype matching and mode of damage, are two species of Curculionidae, the current biological control agent P. guérini and the stem boring moth, Maracayia chiorisalis Walker (Crambidae). The two curculionid species and M. chlorisalis should be considered priorities for host specificity studies. Releases of P. guérini and any new biological control agents should be made at sites where the pre-release study was conducted so that post-release evaluation data can be compared with the pre-release data and the impact of biological control can be evaluated. Retrospective analyses of biological control programmes provide important ways of improving aspects of biological control programmes, such as methods of agent selection. The evaluation of success in biological control programmes is essential for retrospective analyses because factors that have lead to successes or failures can be analysed. Retrospective analyses of biological control programmes, such as this thesis, may improve weed management, thereby contributing to the conservation of natural resources.
- Full Text:
- Authors: Paterson, Iain Douglas
- Date: 2011
- Subjects: Pereskia -- Biological control -- South Africa Cactus -- Biological control -- South Africa Invasive plants -- Biological control -- South Africa Curculionidae -- South Africa Pyralidae -- South Africa Insects as biological pest control agents -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5825 , http://hdl.handle.net/10962/d1007653
- Description: Pereskia aculeata Miller (Cactaceae) is an environmental weed that is damaging to natural ecosystems in South Africa. The plant is native to Central and South America and was first recorded in South Africa in a botanical garden in 1858. In this thesis, research into the biological control of P. aculeata was conducted with the intention of improving the control of the weed. A pre-release study of the relationship between P. aculeata density and native plant biodiversity indicated that P. aculeata has a negative impact on native biodiversity. The native plant biodiversity associated with different P. aculeata densities was used to determine threshold values and goals for the control of the weed. A threshold value of 50% P. aculeata density was calculated, indicating that P. aculeata density must be maintained below 50% in order to conserve native plant biodiversity. The ultimate goal of the control programme should be to maintain P. aculeata densities below 30%. At these densities there was no significant difference in native plant biodiversity from if the weed were absent from the ecosystem. The biological control agent, Phenrica guérini Bechyne (Chrysomelidae), has been released in South Africa but the potential of the agent to impact P. aculeata is not known and no post release evaluation has been conducted. Impact assessment studies indicate that P. guérini does not impact P. aculeata, even at high densities, but the results of greenhouse experiments should be interpreted with caution because of problems with extrapolation into the field. Although observations in the field suggest that P. guérini has reduced P. aculeata densities at one site, it is clear that new biological control agents are needed to reduce the weed to acceptable levels. Identifying the origin of the South African P. aculeata population was believed to be important to the biological control programme due to the disjunct native distribution and intraspecific variation of the species. Natural enemies associated with plant genotypes in different parts of the native distribution may have developed specialised relationships with certain intraspecific variants of the plant, resulting in differences in agent efficacy on certain host plant genotypes. A molecular study indicated that the closest relatives to the South African weed population found in the native distribution were in Rio de Janeiro Province, Brazil. A bioassay experiment in which fitness related traits of the biological control agent, P. guérini, were measured on various P. aculeata genotypes was conducted to determine the importance of host plant intraspecific variation. There was little variation in fitness traits between genotypes and no evidence of intraspecific host plant specialization. Although intraspecific variation had no effect on agent efficacy in the case of P. guérini, it is possible that other natural enemies may be more specialized. Genotype matching is expected to be more important when natural enemies likely to be specialised to individual genotypes are considered for biological control. Potential biological control agents were prioritized from data collected on surveys in the native distribution. The most promising of these, based on the presence of feeding, incidence, predicted host range, climatic matching, genotype matching and mode of damage, are two species of Curculionidae, the current biological control agent P. guérini and the stem boring moth, Maracayia chiorisalis Walker (Crambidae). The two curculionid species and M. chlorisalis should be considered priorities for host specificity studies. Releases of P. guérini and any new biological control agents should be made at sites where the pre-release study was conducted so that post-release evaluation data can be compared with the pre-release data and the impact of biological control can be evaluated. Retrospective analyses of biological control programmes provide important ways of improving aspects of biological control programmes, such as methods of agent selection. The evaluation of success in biological control programmes is essential for retrospective analyses because factors that have lead to successes or failures can be analysed. Retrospective analyses of biological control programmes, such as this thesis, may improve weed management, thereby contributing to the conservation of natural resources.
- Full Text:
Biomechanical, physiological and perceptual responses of three different athlete groups to the cycle-run transition
- Authors: Cripwell, Devin Matthew
- Date: 2011
- Subjects: Biomechanics -- Research , Human mechanics -- Research , Cycling -- Physiological aspects -- Research , Running -- Physiological aspects -- Research , Exercise -- Physiological aspects -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5106 , http://hdl.handle.net/10962/d1005184 , Biomechanics -- Research , Human mechanics -- Research , Cycling -- Physiological aspects -- Research , Running -- Physiological aspects -- Research , Exercise -- Physiological aspects -- Research
- Description: The transition from cycling to running has been identified as one of the key determinants of success in triathlon, as it has been suggested that the cycle may affect subsequent running efficiency such that running performance is significantly altered or reduced. It is also suggested that athletes more adapted to the transition itself, rather than purely running or cycling, may be more efficient during the post-cycle running bout. The current study sought to investigate the effects of prior cycling on subsequent selected biomechanical, physiological and perceptual responses of three different athlete groups. Subjects were selected on the basis of their sporting background, and were divided into three groups – triathletes, cyclists and runners. Experimentation required subjects to perform a seven minute treadmill running protocol at 15km.h⁻¹, during which biomechanical (EMG, Stride rate, Stride length, Vertical acceleration), physiological (HR, VO₂, EE) and perceptual (RPE) responses were recorded. After resting, subjects were required to perform a twenty minute stationary cycle at 70% of maximal aerobic power (previously determined), immediately followed by a second seven minute treadmill running protocol during which the same data were collected and compared to those collected during the first run. Biomechanical responses indicate that the cycle protocol had no effect on the muscle activity or vertical acceleration responses of any of the three subject groups, while the triathlete group significantly altered their gait responses in order to preserve running economy. The triathlete group was the least affected when considering the physiological responses, as running economy was preserved for this group. The runner and cyclist groups were significantly affected by the transition, as running economy decreased significantly for these groups. Perceptual responses indicate that athletes more experienced with the transition may find the transition from cycling to running to be easier than those inexperienced in this transition. It is apparent that a high intensity cycle protocol has limited statistical impact on selected biomechanical responses, while physiological and perceptual responses were altered, during a subsequent run, regardless of athlete type. That said, the ability of transition-trained athletes to transition comfortably between disciplines was highlighted, which may have important performance implications.
- Full Text:
- Authors: Cripwell, Devin Matthew
- Date: 2011
- Subjects: Biomechanics -- Research , Human mechanics -- Research , Cycling -- Physiological aspects -- Research , Running -- Physiological aspects -- Research , Exercise -- Physiological aspects -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5106 , http://hdl.handle.net/10962/d1005184 , Biomechanics -- Research , Human mechanics -- Research , Cycling -- Physiological aspects -- Research , Running -- Physiological aspects -- Research , Exercise -- Physiological aspects -- Research
- Description: The transition from cycling to running has been identified as one of the key determinants of success in triathlon, as it has been suggested that the cycle may affect subsequent running efficiency such that running performance is significantly altered or reduced. It is also suggested that athletes more adapted to the transition itself, rather than purely running or cycling, may be more efficient during the post-cycle running bout. The current study sought to investigate the effects of prior cycling on subsequent selected biomechanical, physiological and perceptual responses of three different athlete groups. Subjects were selected on the basis of their sporting background, and were divided into three groups – triathletes, cyclists and runners. Experimentation required subjects to perform a seven minute treadmill running protocol at 15km.h⁻¹, during which biomechanical (EMG, Stride rate, Stride length, Vertical acceleration), physiological (HR, VO₂, EE) and perceptual (RPE) responses were recorded. After resting, subjects were required to perform a twenty minute stationary cycle at 70% of maximal aerobic power (previously determined), immediately followed by a second seven minute treadmill running protocol during which the same data were collected and compared to those collected during the first run. Biomechanical responses indicate that the cycle protocol had no effect on the muscle activity or vertical acceleration responses of any of the three subject groups, while the triathlete group significantly altered their gait responses in order to preserve running economy. The triathlete group was the least affected when considering the physiological responses, as running economy was preserved for this group. The runner and cyclist groups were significantly affected by the transition, as running economy decreased significantly for these groups. Perceptual responses indicate that athletes more experienced with the transition may find the transition from cycling to running to be easier than those inexperienced in this transition. It is apparent that a high intensity cycle protocol has limited statistical impact on selected biomechanical responses, while physiological and perceptual responses were altered, during a subsequent run, regardless of athlete type. That said, the ability of transition-trained athletes to transition comfortably between disciplines was highlighted, which may have important performance implications.
- Full Text:
Biphenyl sorption to different soil clay minerals
- Tandlich, Roman, Baláž, Štefan
- Authors: Tandlich, Roman , Baláž, Štefan
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76869 , vital:30632 , https://doi.org/10.5897/AJAR10.1012
- Description: Only limited information is available in the literature on the role of soil mineral surfaces in the sorption of hydrophobic organic pollutants. This knowledge gap is addressed through the assessment of biphenyl sorption to kaolinite, illite and bentonite; using the batch equilibration technique with incubations lasting 6 or 21 days at 28 ± 2°C in the dark [RT1]. Sorption of biphenyl onto kaolinite followed the Freundlich sorption isotherm, whereas linear sorption isotherms were observed on illite and bentonite [RT2]. The biphenyl sorption partition coefficient on kaolinite ranged from 0.1 to 9.1 cm3.g-1 after 6 days and no sorption was observed after 21 days. This could have been caused by a completely reversible sorption or a loss of binding capacity after 21 days [RT3]. The respective values of the biphenyl sorption partition coefficient on illite and bentonite ranged from 20.3 ± 0.3 to 120 ± 8 cm3.g-1.Sorption equilibrium on the internal clay surfaces was reached after 6 days, as indicated by the sorption data for illite and bentonite [RT4]. Access of biphenyl molecules to the internal clay surfaces is a function of the ionic strength of soil solution and the soil organic matter is the dominant site for biphenyl sorption after 6 to 21 days.
- Full Text:
- Authors: Tandlich, Roman , Baláž, Štefan
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/76869 , vital:30632 , https://doi.org/10.5897/AJAR10.1012
- Description: Only limited information is available in the literature on the role of soil mineral surfaces in the sorption of hydrophobic organic pollutants. This knowledge gap is addressed through the assessment of biphenyl sorption to kaolinite, illite and bentonite; using the batch equilibration technique with incubations lasting 6 or 21 days at 28 ± 2°C in the dark [RT1]. Sorption of biphenyl onto kaolinite followed the Freundlich sorption isotherm, whereas linear sorption isotherms were observed on illite and bentonite [RT2]. The biphenyl sorption partition coefficient on kaolinite ranged from 0.1 to 9.1 cm3.g-1 after 6 days and no sorption was observed after 21 days. This could have been caused by a completely reversible sorption or a loss of binding capacity after 21 days [RT3]. The respective values of the biphenyl sorption partition coefficient on illite and bentonite ranged from 20.3 ± 0.3 to 120 ± 8 cm3.g-1.Sorption equilibrium on the internal clay surfaces was reached after 6 days, as indicated by the sorption data for illite and bentonite [RT4]. Access of biphenyl molecules to the internal clay surfaces is a function of the ionic strength of soil solution and the soil organic matter is the dominant site for biphenyl sorption after 6 to 21 days.
- Full Text:
Bluetooth audio and video streaming on the J2ME platform
- Authors: Sahd, Curtis Lee
- Date: 2011 , 2010-09-09
- Subjects: Bluetooth technology , Mobile communication systems , Communication -- Technological innovations , Communication -- Network analysis , Wireless communication systems , L2TP (Computer network protocol) , Computer network protocols , Streaming audio , Streaming video
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4633 , http://hdl.handle.net/10962/d1006521 , Bluetooth technology , Mobile communication systems , Communication -- Technological innovations , Communication -- Network analysis , Wireless communication systems , L2TP (Computer network protocol) , Computer network protocols , Streaming audio , Streaming video
- Description: With the increase in bandwidth, more widespread distribution of media, and increased capability of mobile devices, multimedia streaming has not only become feasible, but more economical in terms of space occupied by the media file and the costs involved in attaining it. Although much attention has been paid to peer to peer media streaming over the Internet using HTTP and RTSP, little research has focussed on the use of the Bluetooth protocol for streaming audio and video between mobile devices. This project investigates the feasibility of Bluetooth as a protocol for audio and video streaming between mobile phones using the J2ME platform, through the analysis of Bluetooth protocols, media formats, optimum packet sizes, and the effects of distance on transfer speed. A comparison was made between RFCOMM and L2CAP to determine which protocol could support the fastest transfer speed between two mobile devices. The L2CAP protocol proved to be the most suitable, providing average transfer rates of 136.17 KBps. Using this protocol a second experiment was undertaken to determine the most suitable media format for streaming in terms of: file size, bandwidth usage, quality, and ease of implementation. Out of the eight media formats investigated, the MP3 format provided the smallest file size, smallest bandwidth usage, best quality and highest ease of implementation. Another experiment was conducted to determine the optimum packet size for transfer between devices. A tradeoff was found between packet size and the quality of the sound file, with highest transfer rates being recorded with the MTU size of 668 bytes (136.58 KBps). The class of Bluetooth transmitter typically used in mobile devices (class 2) is considered a weak signal and is adversely affected by distance. As such, the final investigation that was undertaken was aimed at determining the effects of distance on audio streaming and playback. As can be expected, when devices were situated close to each other, the transfer speeds obtained were higher than when devices were far apart. Readings were taken at varying distances (1-15 metres), with erratic transfer speeds observed from 7 metres onwards. This research showed that audio streaming on the J2ME platform is feasible, however using the currently available class of Bluetooth transmitter, video streaming is not feasible. Video files were only playable once the entire media file had been transferred.
- Full Text:
- Authors: Sahd, Curtis Lee
- Date: 2011 , 2010-09-09
- Subjects: Bluetooth technology , Mobile communication systems , Communication -- Technological innovations , Communication -- Network analysis , Wireless communication systems , L2TP (Computer network protocol) , Computer network protocols , Streaming audio , Streaming video
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4633 , http://hdl.handle.net/10962/d1006521 , Bluetooth technology , Mobile communication systems , Communication -- Technological innovations , Communication -- Network analysis , Wireless communication systems , L2TP (Computer network protocol) , Computer network protocols , Streaming audio , Streaming video
- Description: With the increase in bandwidth, more widespread distribution of media, and increased capability of mobile devices, multimedia streaming has not only become feasible, but more economical in terms of space occupied by the media file and the costs involved in attaining it. Although much attention has been paid to peer to peer media streaming over the Internet using HTTP and RTSP, little research has focussed on the use of the Bluetooth protocol for streaming audio and video between mobile devices. This project investigates the feasibility of Bluetooth as a protocol for audio and video streaming between mobile phones using the J2ME platform, through the analysis of Bluetooth protocols, media formats, optimum packet sizes, and the effects of distance on transfer speed. A comparison was made between RFCOMM and L2CAP to determine which protocol could support the fastest transfer speed between two mobile devices. The L2CAP protocol proved to be the most suitable, providing average transfer rates of 136.17 KBps. Using this protocol a second experiment was undertaken to determine the most suitable media format for streaming in terms of: file size, bandwidth usage, quality, and ease of implementation. Out of the eight media formats investigated, the MP3 format provided the smallest file size, smallest bandwidth usage, best quality and highest ease of implementation. Another experiment was conducted to determine the optimum packet size for transfer between devices. A tradeoff was found between packet size and the quality of the sound file, with highest transfer rates being recorded with the MTU size of 668 bytes (136.58 KBps). The class of Bluetooth transmitter typically used in mobile devices (class 2) is considered a weak signal and is adversely affected by distance. As such, the final investigation that was undertaken was aimed at determining the effects of distance on audio streaming and playback. As can be expected, when devices were situated close to each other, the transfer speeds obtained were higher than when devices were far apart. Readings were taken at varying distances (1-15 metres), with erratic transfer speeds observed from 7 metres onwards. This research showed that audio streaming on the J2ME platform is feasible, however using the currently available class of Bluetooth transmitter, video streaming is not feasible. Video files were only playable once the entire media file had been transferred.
- Full Text: