Developing a business model for growth in social enterprise : a case study of a hybrid organisation
- Authors: Olivier, Grant Jerome
- Date: 2013
- Subjects: Social entrepreneurship , Business planning , Free enterprise -- Social aspects , Small business -- Growth
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8854 , http://hdl.handle.net/10948/d1020137
- Description: The Intshona Group of Companies operates in South Africa as a hybrid agribusiness combining entrepreneurial principles with a philosophy of social upliftment in Africa. This research views Intshona through the lens of social entrepreneurship theory, a hybrid research field with a dominant theme being the need for growth and scaling of impact, but which is seen as fragmented, containing ambiguities and lagging practice. In this research, a case study of Intshona is developed based on questionnaires and interviews with the organisation’s management, a concerned NGO, social beneficiaries as well as employees. The result is a two-way flow of knowledge integrating elements of existing social enterprise theory with Intshona’s business practices, building on a generic model of entrepreneurship and culminating in a business model for growth in a social enterprise. The research delivers strategic directives for Intshona for its future growth, presents a case study for addition to the body of knowledge on social entrepreneurship and concludes with suggestions for further research to continue developing theory.
- Full Text:
- Date Issued: 2013
- Authors: Olivier, Grant Jerome
- Date: 2013
- Subjects: Social entrepreneurship , Business planning , Free enterprise -- Social aspects , Small business -- Growth
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8854 , http://hdl.handle.net/10948/d1020137
- Description: The Intshona Group of Companies operates in South Africa as a hybrid agribusiness combining entrepreneurial principles with a philosophy of social upliftment in Africa. This research views Intshona through the lens of social entrepreneurship theory, a hybrid research field with a dominant theme being the need for growth and scaling of impact, but which is seen as fragmented, containing ambiguities and lagging practice. In this research, a case study of Intshona is developed based on questionnaires and interviews with the organisation’s management, a concerned NGO, social beneficiaries as well as employees. The result is a two-way flow of knowledge integrating elements of existing social enterprise theory with Intshona’s business practices, building on a generic model of entrepreneurship and culminating in a business model for growth in a social enterprise. The research delivers strategic directives for Intshona for its future growth, presents a case study for addition to the body of knowledge on social entrepreneurship and concludes with suggestions for further research to continue developing theory.
- Full Text:
- Date Issued: 2013
Developing a virtualised testbed environment in preparation for testing of network based attacks
- Van Heerden, Renier, Pieterse, Heloise, Burke, Ivan, Irwin, Barry V W
- Authors: Van Heerden, Renier , Pieterse, Heloise , Burke, Ivan , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429648 , vital:72629 , 10.1109/ICASTech.2013.6707509
- Description: Computer network attacks are difficult to simulate due to the damage they may cause to live networks and the complexity required simulating a useful network. We constructed a virtualised network within a vSphereESXi environment which is able to simulate: thirty workstations, ten servers, three distinct network segments and the accompanying network traffic. The VSphere environment provided added benefits, such as the ability to pause, restart and snapshot virtual computers. These abilities enabled the authors to reset the simulation environment before each test and mitigated against the damage that an attack potentially inflicts on the test network. Without simulated network traffic, the virtualised network was too sterile. This resulted in any network event being a simple task to detect, making network traffic simulation a requirement for an event detection test bed. Five main kinds of traffic were simulated: Web browsing, File transfer, e-mail, version control and Intranet File traffic. The simulated traffic volumes were pseudo randomised to represent differing temporal patterns. By building a virtualised network with simulated traffic we were able to test IDS' and other network attack detection sensors in a much more realistic environment before moving it to a live network. The goal of this paper is to present a virtualised testbedenvironmentin which network attacks can safely be tested.
- Full Text:
- Date Issued: 2013
- Authors: Van Heerden, Renier , Pieterse, Heloise , Burke, Ivan , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429648 , vital:72629 , 10.1109/ICASTech.2013.6707509
- Description: Computer network attacks are difficult to simulate due to the damage they may cause to live networks and the complexity required simulating a useful network. We constructed a virtualised network within a vSphereESXi environment which is able to simulate: thirty workstations, ten servers, three distinct network segments and the accompanying network traffic. The VSphere environment provided added benefits, such as the ability to pause, restart and snapshot virtual computers. These abilities enabled the authors to reset the simulation environment before each test and mitigated against the damage that an attack potentially inflicts on the test network. Without simulated network traffic, the virtualised network was too sterile. This resulted in any network event being a simple task to detect, making network traffic simulation a requirement for an event detection test bed. Five main kinds of traffic were simulated: Web browsing, File transfer, e-mail, version control and Intranet File traffic. The simulated traffic volumes were pseudo randomised to represent differing temporal patterns. By building a virtualised network with simulated traffic we were able to test IDS' and other network attack detection sensors in a much more realistic environment before moving it to a live network. The goal of this paper is to present a virtualised testbedenvironmentin which network attacks can safely be tested.
- Full Text:
- Date Issued: 2013
Developing principles for research on young women and abortion
- Authors: Macleod, Catriona I
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/434384 , vital:73053 , ISBN 9781919895581 , https://rowman.com/ISBN/9789280812275/Jacketed-Women-Qualitative-Research-Methodologies-on-Sexualities-and-Gender-in-Africa
- Description: Soon after the first democratic elections in South Africa in 1994, the Choice on Termination of Pregnancy (CTOP) Act of 1996, which legalised abortion for the first time, was passed. Women may now request abortions up to the twelfth week of pregnancy. After this, abortions may still be performed but under specified conditions, for instance, if continued pregnancy will significantly affect the woman’s social or economic circumstances. The Act also promotes the provision of non-mandatory counselling before and after abortions are performed. Minors are counselled to notify their parents or guardian but do not require consent for an abortion. Since the introduction of the CTOP, a number of studies have been conducted on abortion in South Africa. Many have taken a health-related focus, for example, studies on the quality of care provided by midwives (Dickson-Tetteh and Billings 2002); profiles of women seeking abortions (Ramonate, Hiemstra, De Coning and Nel 2001); attitudes, beliefs and experiences of health providers (Buga 2002; Da Costa and Donald 2003); the cost of termination of pregnancy services (Reproductive Rights Alliance 2000); prevalence of morbidity in termination of pregnancies (Jewkes, Brown, Dickson-Tetteh, Levin and Rees 2002); the proportion of pregnancies that end in termination of pregnancy (Buchmann, Mensah and Pillay 2002); and impediments in the provision of services (Engelbrecht, Pelser, Ngwena and Van Rensburg 2000).
- Full Text:
- Date Issued: 2013
- Authors: Macleod, Catriona I
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/434384 , vital:73053 , ISBN 9781919895581 , https://rowman.com/ISBN/9789280812275/Jacketed-Women-Qualitative-Research-Methodologies-on-Sexualities-and-Gender-in-Africa
- Description: Soon after the first democratic elections in South Africa in 1994, the Choice on Termination of Pregnancy (CTOP) Act of 1996, which legalised abortion for the first time, was passed. Women may now request abortions up to the twelfth week of pregnancy. After this, abortions may still be performed but under specified conditions, for instance, if continued pregnancy will significantly affect the woman’s social or economic circumstances. The Act also promotes the provision of non-mandatory counselling before and after abortions are performed. Minors are counselled to notify their parents or guardian but do not require consent for an abortion. Since the introduction of the CTOP, a number of studies have been conducted on abortion in South Africa. Many have taken a health-related focus, for example, studies on the quality of care provided by midwives (Dickson-Tetteh and Billings 2002); profiles of women seeking abortions (Ramonate, Hiemstra, De Coning and Nel 2001); attitudes, beliefs and experiences of health providers (Buga 2002; Da Costa and Donald 2003); the cost of termination of pregnancy services (Reproductive Rights Alliance 2000); prevalence of morbidity in termination of pregnancies (Jewkes, Brown, Dickson-Tetteh, Levin and Rees 2002); the proportion of pregnancies that end in termination of pregnancy (Buchmann, Mensah and Pillay 2002); and impediments in the provision of services (Engelbrecht, Pelser, Ngwena and Van Rensburg 2000).
- Full Text:
- Date Issued: 2013
Developing teaching and learning skills at a Higher education institution: a collaborative action research study
- Authors: Mokhele, Paul Rampaola
- Date: 2013
- Subjects: Learning -- Study and teaching (Tertiary) -- South Africa
- Language: English
- Type: Thesis , Doctoral , D Ed
- Identifier: vital:18456 , http://hdl.handle.net/11260/d1007960
- Description: The thesis which was originally undertaken to improve my teaching skills and determine ways of allowing me space to live my academic values also turned out to become the enquiry to investigate students’ learning and study skills. Students and I collaborated in a year-long self-study action research where we were trying different teaching-learning strategies in order to improve our practice(s). Throughout the study I kept a reflective journal and students also reflected in a portfolio of learning their impressions about the new teaching-learning strategies. In addition to these data gathering methods data from students were gathered using chats, observation, and open-ended questionnaire. Data was analysed using a narrative method, reflexivity principle, and grounded theory. There are two major steps I followed in this study which are aimed at improving students’ basic study and learning skills, and my teaching skills. The first relates to action research into student learning at the school of Mathematics Science and Technology (MSTE) at a rural university. The study reveals that: Students have their own different and unique styles of learning, implementing various learning styles afford students an opportunity to find a style that matches their own. The second action step relates to my own self-study research trying different teaching methods based on my academic and personal values. Here, the study reveals that: The best teaching-learning practice is the one developed and agreed upon between the teacher educator and his or her students. These ‘action’ steps were not mutually exclusive – they were conducted in parallel. After the description of developing student learning skills at undergraduate level my reflections on the study followed in relation to theories and methods of teaching-learning and further revealed that what works with one group of students will not necessarily work with another group. The best teacher educator is constantly seeking ways of improving the learning experience of his or her students. The recommendations that teacher educators should become self reflective practitioners and improve their professions using self-study collaborative approach will benefit other teacher educators who are keen to study and improve their practice.
- Full Text:
- Date Issued: 2013
- Authors: Mokhele, Paul Rampaola
- Date: 2013
- Subjects: Learning -- Study and teaching (Tertiary) -- South Africa
- Language: English
- Type: Thesis , Doctoral , D Ed
- Identifier: vital:18456 , http://hdl.handle.net/11260/d1007960
- Description: The thesis which was originally undertaken to improve my teaching skills and determine ways of allowing me space to live my academic values also turned out to become the enquiry to investigate students’ learning and study skills. Students and I collaborated in a year-long self-study action research where we were trying different teaching-learning strategies in order to improve our practice(s). Throughout the study I kept a reflective journal and students also reflected in a portfolio of learning their impressions about the new teaching-learning strategies. In addition to these data gathering methods data from students were gathered using chats, observation, and open-ended questionnaire. Data was analysed using a narrative method, reflexivity principle, and grounded theory. There are two major steps I followed in this study which are aimed at improving students’ basic study and learning skills, and my teaching skills. The first relates to action research into student learning at the school of Mathematics Science and Technology (MSTE) at a rural university. The study reveals that: Students have their own different and unique styles of learning, implementing various learning styles afford students an opportunity to find a style that matches their own. The second action step relates to my own self-study research trying different teaching methods based on my academic and personal values. Here, the study reveals that: The best teaching-learning practice is the one developed and agreed upon between the teacher educator and his or her students. These ‘action’ steps were not mutually exclusive – they were conducted in parallel. After the description of developing student learning skills at undergraduate level my reflections on the study followed in relation to theories and methods of teaching-learning and further revealed that what works with one group of students will not necessarily work with another group. The best teacher educator is constantly seeking ways of improving the learning experience of his or her students. The recommendations that teacher educators should become self reflective practitioners and improve their professions using self-study collaborative approach will benefit other teacher educators who are keen to study and improve their practice.
- Full Text:
- Date Issued: 2013
Development and validation of in-process control test kits for biodiesel production
- Authors: Fibi, Pumza Oscarine
- Date: 2013
- Subjects: Biodiesel fuels -- South Africa , Biomass energy -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10416 , http://hdl.handle.net/10948/d1012645 , Biodiesel fuels -- South Africa , Biomass energy -- South Africa
- Description: The production of biodiesel from vegetable oils is not a new technology; it has been around since the 1950’s and both the research in terms of the different feedstock that can be used and the production of biodiesel has since been gaining momentum as there needs to be a new, sustainable and domestic alternative to petroleum fuels. These petroleum fuels pose enormous threats to the environment and therefore need to be replaced as they are mostly contributing to climate change and global warming not to mention the frequent price hikes which are crippling the South African economy. Biodiesel production using vegetable oils seems to be and is the future and a law has recently been passed which sanctions the production of biofuel locally.[1] South African fuel producers will instigate obligatory blending of fossil fuel with biofuel as the country moves to encourage investment in its biofuels sector. The production of biodiesel locally and the blending of biodiesel with other petroleum products will reduce the country’s dependence on imported fuel. The already established petrochemical companies like BP, Sasol and Engine are therefore mandated to purchase these biofuels if and when the biofuels meet the required South African National Standard (SANS) 1935 requirements. This is then where the challenge comes as most of these growing biofuel companies cannot afford to purchase testing equipment.The growing companiesthen discover upon completion of the biofuel manufacturing process that their product does not meet the required standard specification. The failure translates to a financial loss as the final product can possibly not be reworked. The aim of the project is then to assist these companies who are manufacturing biofuel, by providing them with in-house biofuel process methods which will allow for early detection, should there be a need to redo a step in the process and not wait until the completion of the production process. These in-house process-testing methods will range from pH determination, titration tests which will determine the soap content and the percentage free fatty acid content, water determination, density and visual testing. It is not cost-effective for these biodiesel manufacturers to send their samples for outsource testing as evidently the results obtained would be out of specification hence the need to provide these biodiesel manufacturers with in-house analytical testing techniques that will aid in monitoring of the biodiesel production.
- Full Text:
- Date Issued: 2013
- Authors: Fibi, Pumza Oscarine
- Date: 2013
- Subjects: Biodiesel fuels -- South Africa , Biomass energy -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10416 , http://hdl.handle.net/10948/d1012645 , Biodiesel fuels -- South Africa , Biomass energy -- South Africa
- Description: The production of biodiesel from vegetable oils is not a new technology; it has been around since the 1950’s and both the research in terms of the different feedstock that can be used and the production of biodiesel has since been gaining momentum as there needs to be a new, sustainable and domestic alternative to petroleum fuels. These petroleum fuels pose enormous threats to the environment and therefore need to be replaced as they are mostly contributing to climate change and global warming not to mention the frequent price hikes which are crippling the South African economy. Biodiesel production using vegetable oils seems to be and is the future and a law has recently been passed which sanctions the production of biofuel locally.[1] South African fuel producers will instigate obligatory blending of fossil fuel with biofuel as the country moves to encourage investment in its biofuels sector. The production of biodiesel locally and the blending of biodiesel with other petroleum products will reduce the country’s dependence on imported fuel. The already established petrochemical companies like BP, Sasol and Engine are therefore mandated to purchase these biofuels if and when the biofuels meet the required South African National Standard (SANS) 1935 requirements. This is then where the challenge comes as most of these growing biofuel companies cannot afford to purchase testing equipment.The growing companiesthen discover upon completion of the biofuel manufacturing process that their product does not meet the required standard specification. The failure translates to a financial loss as the final product can possibly not be reworked. The aim of the project is then to assist these companies who are manufacturing biofuel, by providing them with in-house biofuel process methods which will allow for early detection, should there be a need to redo a step in the process and not wait until the completion of the production process. These in-house process-testing methods will range from pH determination, titration tests which will determine the soap content and the percentage free fatty acid content, water determination, density and visual testing. It is not cost-effective for these biodiesel manufacturers to send their samples for outsource testing as evidently the results obtained would be out of specification hence the need to provide these biodiesel manufacturers with in-house analytical testing techniques that will aid in monitoring of the biodiesel production.
- Full Text:
- Date Issued: 2013
Development of a co-operative stakeholder framework for employment growth in the South African automotive sector
- Authors: Smith, Owen Christo
- Date: 2013
- Subjects: Cooperative societies -- South Africa , Job creation -- South Africa , Automobile industry and trade -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8884 , http://hdl.handle.net/10948/d1020799
- Description: Manufacturing has been identified by the Department of Trade and Industry as an important sector to drive economic growth in South Africa. The automotive manufacturing sector in particular has seen significant support from the DTI in the form of incentives to produce motor vehicles and components. South Africa is faced with a high unemployment rate and one of the strategies of the Government is to drive economic growth by supporting the automotive manufacturing sector. One of the spill-over targets is to increase employment creation in the industry. The automotive manufacturing sector consists of a diverse list of stakeholders representing motor vehicle manufacturers, component manufacturers, labour unions, government departments and industry associations. The Motor Industry Development Programme delivered significant progress in the number of vehicles produced in South Africa and the biggest growth was in the export of vehicles. Employment creation on the other hand did not see the same levels of growth as motor vehicle and component production. The purpose of this study was to identify and clarify what the variables are that influence employment creation and to develop a co-operation framework that would guide the automotive cluster stakeholders to work on employment creation initiatives as a collective. The survey questionnaire results representing the perception of managers showed that: - DTI Incentives schemes linked to employment creation; - Productivity, Technology and employment; - The role of competitiveness in the auto cluster; - Labour Union Collective bargaining; - Investment climate and infrastructure; - Education and skills development; does have an influence on employment creation in the automotive cluster.
- Full Text:
- Date Issued: 2013
- Authors: Smith, Owen Christo
- Date: 2013
- Subjects: Cooperative societies -- South Africa , Job creation -- South Africa , Automobile industry and trade -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8884 , http://hdl.handle.net/10948/d1020799
- Description: Manufacturing has been identified by the Department of Trade and Industry as an important sector to drive economic growth in South Africa. The automotive manufacturing sector in particular has seen significant support from the DTI in the form of incentives to produce motor vehicles and components. South Africa is faced with a high unemployment rate and one of the strategies of the Government is to drive economic growth by supporting the automotive manufacturing sector. One of the spill-over targets is to increase employment creation in the industry. The automotive manufacturing sector consists of a diverse list of stakeholders representing motor vehicle manufacturers, component manufacturers, labour unions, government departments and industry associations. The Motor Industry Development Programme delivered significant progress in the number of vehicles produced in South Africa and the biggest growth was in the export of vehicles. Employment creation on the other hand did not see the same levels of growth as motor vehicle and component production. The purpose of this study was to identify and clarify what the variables are that influence employment creation and to develop a co-operation framework that would guide the automotive cluster stakeholders to work on employment creation initiatives as a collective. The survey questionnaire results representing the perception of managers showed that: - DTI Incentives schemes linked to employment creation; - Productivity, Technology and employment; - The role of competitiveness in the auto cluster; - Labour Union Collective bargaining; - Investment climate and infrastructure; - Education and skills development; does have an influence on employment creation in the automotive cluster.
- Full Text:
- Date Issued: 2013
Development of a creep sample retrieval technique and friction weld site repair procedure
- Authors: Wedderburn, Ian Norman
- Date: 2013
- Subjects: Friction welding
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9635 , http://hdl.handle.net/10948/d1020116
- Description: The remnant life monitoring of creep loaded high temperature and pressure components in power stations is critical to ensuring their safe and cost effective operation as failures can have severe consequences. Effective creep life condition monitoring allows for optimising component life predictions and subsequent plant maintenance decisions. In South Africa many power generation stations have been in operation well beyond their 30 year design service life, as such knowledge of the remnant creep life of high temperature and pressure components, such as steam pipelines, becomes of utmost importance. Techniques for the remnant creep life assessments of critical high temperature and pressure components must therefore be as effective as possible. The common and well accepted in-situ inspection technique for assessing creep damage in steam pipes is by the metallographic replication technique. The technique is however limited to the outer surface of the pipe, without information on damage within the wall. This research will illustrate a means of obtaining a sample for creep life analysis with depth through the wall of a pipe, as wells as an alternative technique for the repair of the sample retrieval site. A sample retrieval technique was developed that would retrieve a small diameter cylindrical sample from a cored blind hole for creep analysis by visual creep void assessment or by the small punch creep test. The small punch creep test requires only a small diameter thin disc of material for testing for which its results are comparable with conventional uniaxial creep testing which requires a much larger sample of material. The smaller sample requirement of the small punch creep test therefore allows for a vastly reduced invasive sample retrieval operation and consequently smaller repair size area. Also the fact that the sample is retrieved from a blind hole is advantageous since the pipe wall is not penetrated which would require full plant shutdown. A friction welding technique was identified as an alternative to traditional arc fusion welding for the repair of the sample retrieval site, this technique being the Friction Hydro Pillar Processing technique. Friction Hydro Pillar Processing is a solid-state welding technique and as such has a number of inherent benefits over arc fusion welding as the weld is performed below the melting temperature of the material. From a process point of view Friction Hydro Pillar Processing is ideally suited for automation, has virtually no fumes generated, minimal distortion is experienced and no spatter has to be removed afterwards. The technique has yet to see industrial application and as such development of suitable process parameters was undertaken. Finally, to apply the sample retrieval and repair operations in-situ to a steam pipe in a power plant suitable equipment was developed. Existing friction welding equipment is generally bulky workshop based equipment and is unsuitable for on-site work due to its size and weight. Therefore development of dedicated equipment was required to enable Friction Hydro Pillar Processing to be applied to steam pipes within a power plant environment.
- Full Text:
- Date Issued: 2013
- Authors: Wedderburn, Ian Norman
- Date: 2013
- Subjects: Friction welding
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9635 , http://hdl.handle.net/10948/d1020116
- Description: The remnant life monitoring of creep loaded high temperature and pressure components in power stations is critical to ensuring their safe and cost effective operation as failures can have severe consequences. Effective creep life condition monitoring allows for optimising component life predictions and subsequent plant maintenance decisions. In South Africa many power generation stations have been in operation well beyond their 30 year design service life, as such knowledge of the remnant creep life of high temperature and pressure components, such as steam pipelines, becomes of utmost importance. Techniques for the remnant creep life assessments of critical high temperature and pressure components must therefore be as effective as possible. The common and well accepted in-situ inspection technique for assessing creep damage in steam pipes is by the metallographic replication technique. The technique is however limited to the outer surface of the pipe, without information on damage within the wall. This research will illustrate a means of obtaining a sample for creep life analysis with depth through the wall of a pipe, as wells as an alternative technique for the repair of the sample retrieval site. A sample retrieval technique was developed that would retrieve a small diameter cylindrical sample from a cored blind hole for creep analysis by visual creep void assessment or by the small punch creep test. The small punch creep test requires only a small diameter thin disc of material for testing for which its results are comparable with conventional uniaxial creep testing which requires a much larger sample of material. The smaller sample requirement of the small punch creep test therefore allows for a vastly reduced invasive sample retrieval operation and consequently smaller repair size area. Also the fact that the sample is retrieved from a blind hole is advantageous since the pipe wall is not penetrated which would require full plant shutdown. A friction welding technique was identified as an alternative to traditional arc fusion welding for the repair of the sample retrieval site, this technique being the Friction Hydro Pillar Processing technique. Friction Hydro Pillar Processing is a solid-state welding technique and as such has a number of inherent benefits over arc fusion welding as the weld is performed below the melting temperature of the material. From a process point of view Friction Hydro Pillar Processing is ideally suited for automation, has virtually no fumes generated, minimal distortion is experienced and no spatter has to be removed afterwards. The technique has yet to see industrial application and as such development of suitable process parameters was undertaken. Finally, to apply the sample retrieval and repair operations in-situ to a steam pipe in a power plant suitable equipment was developed. Existing friction welding equipment is generally bulky workshop based equipment and is unsuitable for on-site work due to its size and weight. Therefore development of dedicated equipment was required to enable Friction Hydro Pillar Processing to be applied to steam pipes within a power plant environment.
- Full Text:
- Date Issued: 2013
Development of a novel, quantitative assay for determining the rate of activity of antimalarial drugs
- Authors: Khan, Tasmiyah
- Date: 2013
- Subjects: Assay , ATP , Antimalarials -- Therapeutic use Malaria Malaria -- Drug therapy Adenosine triphosphate Luciferases Plasmodium falciparum
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3884 , http://hdl.handle.net/10962/d1001618
- Description: Malaria, caused by an intracellular Plasmodium parasite, remains a devastating disease, having claimed approximately 655 000 lives worldwide in 2010. The Medicines for Malaria Venture suggests a "single-dose radical cure" as the ideal malaria treatment since rapid clearance of blood-stage parasites and symptom relief improves patient compliance and limits drug resistance. Thus, novel antimalarials should be rapid-acting and assessing their rate of activity is critical to drug discovery. Traditional evaluation of this rate by morphological assessments is flawed by highly subjective, operator-specific interpretations, mainly due to heterogeneous parasite morphology under routine culture conditions. This study aimed to develop an alternative, quantitative assay. Energy is vital for the growth and maintenance of all living organisms. Commercially available kits allow rapid quantification of the cell's energy currency, ATP. Therefore, quantification of parasite ATP shows potential for diagnosing abnormal parasite metabolism and the kinetics of drug action. In this study, a rapid protocol for detecting ATP in Plasmodium falciparum parasites using a luminescence-based kit was developed and optimised. Furthermore, luciferase-expressing transgenic parasites, in which luciferase activity is detected using a similar kit, were acquired. The utility of both methods for evaluating the rate of drug-induced stress was explored using antimalarials with varying modes of action and, presumably, rates of activity. Results showed that parasite ATP remained unchanged, increased or decreased during drug exposure. Morphological examinations by light microscopy and a Recovery assay, aided interpretation of the drug-induced changes in parasite ATP. These investigations suggested that unchanged parasite ATP levels reflect poor drug action, increased ATP levels indicate a stress response and partially compromised viability, while significantly reduced ATP reflects severely compromised viability. Concerning the Luciferase assay, parasite luciferase activity decreased during drug exposure, even in the presence of proteasome inhibitors. Changes in parasite ATP and luciferase activity occurred at rates which suggested that chloroquine is slow-acting, mefloquine has a moderate rate of activity and artemisinin is rapid-acting. These findings are compatible with the expected rates of activity of these established antimalarials. Hence, measurement of parasite ATP and/or luciferase activity may support assessments of parasite health and the kinetics of antimalarial action during drug discovery
- Full Text:
- Date Issued: 2013
- Authors: Khan, Tasmiyah
- Date: 2013
- Subjects: Assay , ATP , Antimalarials -- Therapeutic use Malaria Malaria -- Drug therapy Adenosine triphosphate Luciferases Plasmodium falciparum
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3884 , http://hdl.handle.net/10962/d1001618
- Description: Malaria, caused by an intracellular Plasmodium parasite, remains a devastating disease, having claimed approximately 655 000 lives worldwide in 2010. The Medicines for Malaria Venture suggests a "single-dose radical cure" as the ideal malaria treatment since rapid clearance of blood-stage parasites and symptom relief improves patient compliance and limits drug resistance. Thus, novel antimalarials should be rapid-acting and assessing their rate of activity is critical to drug discovery. Traditional evaluation of this rate by morphological assessments is flawed by highly subjective, operator-specific interpretations, mainly due to heterogeneous parasite morphology under routine culture conditions. This study aimed to develop an alternative, quantitative assay. Energy is vital for the growth and maintenance of all living organisms. Commercially available kits allow rapid quantification of the cell's energy currency, ATP. Therefore, quantification of parasite ATP shows potential for diagnosing abnormal parasite metabolism and the kinetics of drug action. In this study, a rapid protocol for detecting ATP in Plasmodium falciparum parasites using a luminescence-based kit was developed and optimised. Furthermore, luciferase-expressing transgenic parasites, in which luciferase activity is detected using a similar kit, were acquired. The utility of both methods for evaluating the rate of drug-induced stress was explored using antimalarials with varying modes of action and, presumably, rates of activity. Results showed that parasite ATP remained unchanged, increased or decreased during drug exposure. Morphological examinations by light microscopy and a Recovery assay, aided interpretation of the drug-induced changes in parasite ATP. These investigations suggested that unchanged parasite ATP levels reflect poor drug action, increased ATP levels indicate a stress response and partially compromised viability, while significantly reduced ATP reflects severely compromised viability. Concerning the Luciferase assay, parasite luciferase activity decreased during drug exposure, even in the presence of proteasome inhibitors. Changes in parasite ATP and luciferase activity occurred at rates which suggested that chloroquine is slow-acting, mefloquine has a moderate rate of activity and artemisinin is rapid-acting. These findings are compatible with the expected rates of activity of these established antimalarials. Hence, measurement of parasite ATP and/or luciferase activity may support assessments of parasite health and the kinetics of antimalarial action during drug discovery
- Full Text:
- Date Issued: 2013
Development of thick section friction stir welding using a sliding tool shoulder
- Authors: Chetty, Shamalin
- Date: 2013
- Subjects: Friction welding
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9633 , http://hdl.handle.net/10948/d1015081
- Description: Sliding shoulder friction stir welding (SSFSW) is an alternative joining technique to the conventional friction stir welding process. The welding mechanism comprises of a rotating probe and a non-rotating shoulder. The shoulder therefore does not contribute to any heat generation or plastic deformation. When welding thicker section material, the contribution of heat generation from the shoulder becomes less significant and most of the heat and plastic deformation must be generated by the tool probe. For this reason it was decided to develop the process for thick section AA6082-T6. Due to the stationary (non-rotating) shoulder the weld track is smooth and there is no reduction in cross-sectional area. This research is based on the development of a sliding shoulder friction stir welding tool with the ability to create joints of up to 25mm thick on aluminium alloy 6082-T6 plate as well as the associated process development. The sliding shoulder friction stir welding tool was designed, manufactured and tested by initially performing partial penetration welds with various size tool probes and then finally by performing a sliding shoulder friction stir butt weld on 25mm thick plate. As welds were performed and more knowledge gained about the process, design modifications were made. These included varying the clearance between the tool probe and stationary shoulder; the profile of the shoulder which contributes to material flow during the process; and supporting the tool probe to prevent deflection when welding thicker sections at high forge forces. From the sliding shoulder friction stir welds performed, an understanding of material flow during the process was gained when analysing the macro-sections and exit holes of the welds. Typical process forces and torques associated with the process were measured to assist with future head unit and tool designs with regard to sliding shoulder friction stir welding.
- Full Text:
- Date Issued: 2013
- Authors: Chetty, Shamalin
- Date: 2013
- Subjects: Friction welding
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9633 , http://hdl.handle.net/10948/d1015081
- Description: Sliding shoulder friction stir welding (SSFSW) is an alternative joining technique to the conventional friction stir welding process. The welding mechanism comprises of a rotating probe and a non-rotating shoulder. The shoulder therefore does not contribute to any heat generation or plastic deformation. When welding thicker section material, the contribution of heat generation from the shoulder becomes less significant and most of the heat and plastic deformation must be generated by the tool probe. For this reason it was decided to develop the process for thick section AA6082-T6. Due to the stationary (non-rotating) shoulder the weld track is smooth and there is no reduction in cross-sectional area. This research is based on the development of a sliding shoulder friction stir welding tool with the ability to create joints of up to 25mm thick on aluminium alloy 6082-T6 plate as well as the associated process development. The sliding shoulder friction stir welding tool was designed, manufactured and tested by initially performing partial penetration welds with various size tool probes and then finally by performing a sliding shoulder friction stir butt weld on 25mm thick plate. As welds were performed and more knowledge gained about the process, design modifications were made. These included varying the clearance between the tool probe and stationary shoulder; the profile of the shoulder which contributes to material flow during the process; and supporting the tool probe to prevent deflection when welding thicker sections at high forge forces. From the sliding shoulder friction stir welds performed, an understanding of material flow during the process was gained when analysing the macro-sections and exit holes of the welds. Typical process forces and torques associated with the process were measured to assist with future head unit and tool designs with regard to sliding shoulder friction stir welding.
- Full Text:
- Date Issued: 2013
Diet and foraging distribution of gentoo penguins pygoscelis papua at Cow Bay, Falkland Islands
- Authors: Handley, Jonathan Murray
- Date: 2013
- Subjects: Gentoo penguin -- Food -- Falkland Islands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10724 , http://hdl.handle.net/10948/d1020377
- Description: Knowledge of diet and distribution in marine top predators is critical in interpreting their ecological role. Furthermore, this information is required for effective management and conservation of these species. For gentoo penguins at the Falkland Islands a previous overlap in dietary items with commercial fisheries was recognised. Despite this the at-sea distribution has been poorly studied and only at a few localities. Therefore, this thesis looks to broaden the knowledge of foraging ecology for gentoo penguins at another site in the archipelago, Cow Bay. The aim was firstly, through stomach content analysis, to determine if diet changed over a large temporal scale (2002/03/04 – 2011/12/13), and between the chick guard and crèche periods of chick rearing. Secondly, through GPS loggers, to assess distribution at sea during the incubation and chick guard periods (2012/13). Additionally, foraging ecology between genders was investigated. Gentoo penguins at Cow Bay foraged primarily on fish (66-99 percent) throughout the entire study period. The principle prey item by mass was Patagonotothen spp., considered previously as discard by fisheries but now an important commercial resource, for all periods (47-78 percent) except that of the 2012/13 crèche period (19 percent). During this period Sprattus fugensis made up the bulk of the diet (52 percent). Cephalopods, particularly Loligo gahi (1-24 percent), were also prominent in the diet and crustaceans contributed negligibly. The diet indicated that gentoo penguins are capable of both a benthic and pelagic feeding strategy which likely reflects changes in local prey abundance. Birds typically conducted foraging activities during daylight hours with greater trip duration, path length, maximum distance and area utilised during the incubation period than the guard. All trips were confined to the continental shelf and within the boundaries of a marine management zone, the Falkland Islands Interim Conservation Zone (FICZ). Males and females fed on the same size and composition of prey items. Trip duration, path length and maximum distance from the colony were not significantly different, although males foraged in a slightly larger area than females marginally to the north. As at-sea distribution was confined within the FICZ this management area provides protection to food resources of gentoo penguins breeding at Cow Bay. At this site, the population is increasing, likely associated with increased prey availability as evidenced by record catches of Patagonotothen spp. in recent years at the Falkland Islands. Continued long term monitoring of gentoo penguin diet and fishery yields to allow detection of possible competition in the future is recommended. As marine sentinels, on-going monitoring of gentoo penguin populations at the Falkland Islands is likely to provide early warning signs of reduced prey availability.
- Full Text:
- Date Issued: 2013
- Authors: Handley, Jonathan Murray
- Date: 2013
- Subjects: Gentoo penguin -- Food -- Falkland Islands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10724 , http://hdl.handle.net/10948/d1020377
- Description: Knowledge of diet and distribution in marine top predators is critical in interpreting their ecological role. Furthermore, this information is required for effective management and conservation of these species. For gentoo penguins at the Falkland Islands a previous overlap in dietary items with commercial fisheries was recognised. Despite this the at-sea distribution has been poorly studied and only at a few localities. Therefore, this thesis looks to broaden the knowledge of foraging ecology for gentoo penguins at another site in the archipelago, Cow Bay. The aim was firstly, through stomach content analysis, to determine if diet changed over a large temporal scale (2002/03/04 – 2011/12/13), and between the chick guard and crèche periods of chick rearing. Secondly, through GPS loggers, to assess distribution at sea during the incubation and chick guard periods (2012/13). Additionally, foraging ecology between genders was investigated. Gentoo penguins at Cow Bay foraged primarily on fish (66-99 percent) throughout the entire study period. The principle prey item by mass was Patagonotothen spp., considered previously as discard by fisheries but now an important commercial resource, for all periods (47-78 percent) except that of the 2012/13 crèche period (19 percent). During this period Sprattus fugensis made up the bulk of the diet (52 percent). Cephalopods, particularly Loligo gahi (1-24 percent), were also prominent in the diet and crustaceans contributed negligibly. The diet indicated that gentoo penguins are capable of both a benthic and pelagic feeding strategy which likely reflects changes in local prey abundance. Birds typically conducted foraging activities during daylight hours with greater trip duration, path length, maximum distance and area utilised during the incubation period than the guard. All trips were confined to the continental shelf and within the boundaries of a marine management zone, the Falkland Islands Interim Conservation Zone (FICZ). Males and females fed on the same size and composition of prey items. Trip duration, path length and maximum distance from the colony were not significantly different, although males foraged in a slightly larger area than females marginally to the north. As at-sea distribution was confined within the FICZ this management area provides protection to food resources of gentoo penguins breeding at Cow Bay. At this site, the population is increasing, likely associated with increased prey availability as evidenced by record catches of Patagonotothen spp. in recent years at the Falkland Islands. Continued long term monitoring of gentoo penguin diet and fishery yields to allow detection of possible competition in the future is recommended. As marine sentinels, on-going monitoring of gentoo penguin populations at the Falkland Islands is likely to provide early warning signs of reduced prey availability.
- Full Text:
- Date Issued: 2013
Digital multimedia network with latency control
- Gurdan, Robby, Foss, Richard
- Authors: Gurdan, Robby , Foss, Richard
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427043 , vital:72410 , https://patentimages.storage.googleapis.com/59/e3/43/6b49b528623ea3/US8477812.pdf
- Description: The present invention relates to a digital multimedia network 1 with latency control comprising apparatuses for processing of data streams, wherein a borderline input apparatus providing a data stream generates a latency time stamp (LTS) which contains an absolute time indicating a creation time of said data stream and an accumulated delay time which is updated by each apparatus processing said data stream, wherein said latency time stamp (LTS) of said data stream is evaluated by a borderline output apparatus of said network which synchronizes said data stream.
- Full Text:
- Date Issued: 2013
- Authors: Gurdan, Robby , Foss, Richard
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427043 , vital:72410 , https://patentimages.storage.googleapis.com/59/e3/43/6b49b528623ea3/US8477812.pdf
- Description: The present invention relates to a digital multimedia network 1 with latency control comprising apparatuses for processing of data streams, wherein a borderline input apparatus providing a data stream generates a latency time stamp (LTS) which contains an absolute time indicating a creation time of said data stream and an accumulated delay time which is updated by each apparatus processing said data stream, wherein said latency time stamp (LTS) of said data stream is evaluated by a borderline output apparatus of said network which synchronizes said data stream.
- Full Text:
- Date Issued: 2013
Disaster risk reduction in Namibia (flooding): responses and best practices
- Authors: Van der Ross, Nolan Lloyd
- Date: 2013
- Subjects: Flood damage prevention -- Risk assessment , delete
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9241 , http://hdl.handle.net/10948/d1021114
- Description: This study was undertaken in order to obtain an understanding of how Namibia in general, and the education sector in particular, deal with flood emergencies. The goal of the National Policy for Disaster Risk Management in Namibia (2009) is “to contribute to the attainment of sustainable development in line with Namibia’s Vision 2030 through strengthening national capacities to significantly reduce disaster risk and built community resilience to disasters” (Republic of Namibia, 2009). This goal was the starting point for determining the extent to which the Ministry of Education complies with these national standards, and for gauging, in the light of responses to flood emergencies so far, the Ministry’s preparedness and response capacities, in line with international frameworks that Namibia has ratified. This qualitative study is situated within the theory of resilience, and sustainable resilience particularly. To obtain some of the information sought, a non-probability sampling method was used to ‘hand-pick’ subjects within the Ministry of Education to be interviewed at their respective locations, nationally and regionally. Five education officials who were intimately involved in past responses to flood emergencies were interviewed – three in Oshana and Ohangwena Regions, and two at Head Office in Windhoek – by means of a semi-structured interview. In addition, a literature review was conducted. The conclusions drawn from both the literature review and the information obtained from the respondents accord with the research problem identified: the Ministry of Education does not appear to be adequately prepared for, and does not assign the necessary priority to deal with, flood emergencies in particular. Possible recommendations for uptake within the Ministry of Education include: mainstreaming Disaster Risk Reduction at all decentralized levels; sensitizing all education officials, school community members and relevant stakeholders to policy frameworks and accountability structures to strengthen resilience within school communities; deeming costed contingency planning a priority, and hence strengthening links between decentralized regional structures; and continuously monitoring implementation of designed interventions.
- Full Text:
- Date Issued: 2013
- Authors: Van der Ross, Nolan Lloyd
- Date: 2013
- Subjects: Flood damage prevention -- Risk assessment , delete
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9241 , http://hdl.handle.net/10948/d1021114
- Description: This study was undertaken in order to obtain an understanding of how Namibia in general, and the education sector in particular, deal with flood emergencies. The goal of the National Policy for Disaster Risk Management in Namibia (2009) is “to contribute to the attainment of sustainable development in line with Namibia’s Vision 2030 through strengthening national capacities to significantly reduce disaster risk and built community resilience to disasters” (Republic of Namibia, 2009). This goal was the starting point for determining the extent to which the Ministry of Education complies with these national standards, and for gauging, in the light of responses to flood emergencies so far, the Ministry’s preparedness and response capacities, in line with international frameworks that Namibia has ratified. This qualitative study is situated within the theory of resilience, and sustainable resilience particularly. To obtain some of the information sought, a non-probability sampling method was used to ‘hand-pick’ subjects within the Ministry of Education to be interviewed at their respective locations, nationally and regionally. Five education officials who were intimately involved in past responses to flood emergencies were interviewed – three in Oshana and Ohangwena Regions, and two at Head Office in Windhoek – by means of a semi-structured interview. In addition, a literature review was conducted. The conclusions drawn from both the literature review and the information obtained from the respondents accord with the research problem identified: the Ministry of Education does not appear to be adequately prepared for, and does not assign the necessary priority to deal with, flood emergencies in particular. Possible recommendations for uptake within the Ministry of Education include: mainstreaming Disaster Risk Reduction at all decentralized levels; sensitizing all education officials, school community members and relevant stakeholders to policy frameworks and accountability structures to strengthen resilience within school communities; deeming costed contingency planning a priority, and hence strengthening links between decentralized regional structures; and continuously monitoring implementation of designed interventions.
- Full Text:
- Date Issued: 2013
Does national sporting performance affect stock market returns in South Africa?
- Authors: Botha, Ferdi , De Beer, Carl
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396023 , vital:69144 , xlink:href="https://hdl.handle.net/10520/EJC135922"
- Description: This study explores whether South African national sporting performance can influence investors in such a way that it has the ability to impact on market returns. Using standard event study methodology, this study determines the constant mean return using the daily All-Share price index on the JSE for the period of 1 January 1990 to 31 December 2010. This study focuses on three of South Africa's most popular sports, namely soccer, cricket and rugby, and examines if these three sports have the ability to influence market returns. Although there is some evidence of a relationship between stock returns and sporting performance in the descriptive analysis, the regression results indicate that sporting performance in South Africa does not significantly explain abnormal market returns on the JSE. The study provides a number of possible reasons for this finding and concludes by suggesting areas for future research.
- Full Text:
- Date Issued: 2013
- Authors: Botha, Ferdi , De Beer, Carl
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396023 , vital:69144 , xlink:href="https://hdl.handle.net/10520/EJC135922"
- Description: This study explores whether South African national sporting performance can influence investors in such a way that it has the ability to impact on market returns. Using standard event study methodology, this study determines the constant mean return using the daily All-Share price index on the JSE for the period of 1 January 1990 to 31 December 2010. This study focuses on three of South Africa's most popular sports, namely soccer, cricket and rugby, and examines if these three sports have the ability to influence market returns. Although there is some evidence of a relationship between stock returns and sporting performance in the descriptive analysis, the regression results indicate that sporting performance in South Africa does not significantly explain abnormal market returns on the JSE. The study provides a number of possible reasons for this finding and concludes by suggesting areas for future research.
- Full Text:
- Date Issued: 2013
Dog wars : a Victorian steampunk adventure
- Authors: Molino, Nicolene Chloe
- Date: 2013
- Subjects: Creative writing , Fiction , South Africa , Creative writing (Higher education) , Short stories, South African (English) -- 21st century , South African fiction (English) -- 21st century , English language -- Writing
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:5965 , http://hdl.handle.net/10962/d1001815
- Description: We're in an alternate universe, circa Dickensian London. Leofric Lieven, a local crime lord, is about to find the past catching up on him. The Romany Carnival has come to town, and a gypsy woman, his former lover and partner in crime, demands from him a favour which will redress his betrayal of years before: he must secure a stolen object and return it to her. But things go horribly wrong when local delivery boy Cards Bennish is kidnapped by Leofric’s competitor before he can deliver the goods that will cover Leofric's debt to the gypsy. In this world, humans can shape shift into animals, entirely or only partially, dog fighting is the favourite pastime for high stakes betting, and power belongs to the highest bidder. The gypsy’s final bet, for the highest stakes yet, will seal the fates of a number of people, for better or worse
- Full Text:
- Date Issued: 2013
- Authors: Molino, Nicolene Chloe
- Date: 2013
- Subjects: Creative writing , Fiction , South Africa , Creative writing (Higher education) , Short stories, South African (English) -- 21st century , South African fiction (English) -- 21st century , English language -- Writing
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:5965 , http://hdl.handle.net/10962/d1001815
- Description: We're in an alternate universe, circa Dickensian London. Leofric Lieven, a local crime lord, is about to find the past catching up on him. The Romany Carnival has come to town, and a gypsy woman, his former lover and partner in crime, demands from him a favour which will redress his betrayal of years before: he must secure a stolen object and return it to her. But things go horribly wrong when local delivery boy Cards Bennish is kidnapped by Leofric’s competitor before he can deliver the goods that will cover Leofric's debt to the gypsy. In this world, humans can shape shift into animals, entirely or only partially, dog fighting is the favourite pastime for high stakes betting, and power belongs to the highest bidder. The gypsy’s final bet, for the highest stakes yet, will seal the fates of a number of people, for better or worse
- Full Text:
- Date Issued: 2013
Drivers of macrophyte assemblages in South African freshwater systems
- Authors: Martin, Grant Douglas
- Date: 2013
- Subjects: Freshwater plants -- South Africa Aquatic weeds -- South Africa Invasive plants -- South Africa Freshwater ecology -- South Africa Biotic communities -- South Africa Maximum entropy method Lagarosiphon major -- South Africa Phytophagous insects -- South Africa Hydrellia -- South Africa Parasitoids -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5621 , http://hdl.handle.net/10962/d1004127
- Description: Potentially damaging submerged invasive freshwater macrophytes have been identified in South African freshwater systems, but have received less attention than their floating counterparts. To ascertain the changes and effects that these species may have on macrophyte ecology, an understanding of the drivers of macrophyte assemblages is essential. The aims of this thesis were to investigate select abiotic and biotic factors driving introduction, establishment and spread of submerged macrophytes in South Africa. Surveys on the status of submerged plant species in South Africa were conducted to find out the distribution and diversity of the species present, imported to, and traded in South Africa. Numerous submerged indigenous and invasive macrophyte locality records were collected during field surveys, of which many were first time records. Pet stores and aquarist trading activities were identified as potential vectors for the spread of submerged macrophytes through online surveys and personal interviews. These results highlighted the potential these species have for continuing to enter, and spread within South African water bodies. Maximum Entropy (MAXENT) is a general-purpose method used to predict or infer distributions from incomplete information, and was used here to predict areas suitable for the establishment of five of these invasive macrophytes. Many systems throughout South Africa, particularly those in the subtropical coastal regions, were found to be climatically suitable for the establishment of Elodea canadensis Michx., Egeria densa Planch., Hydrilla verticillata (L.f.) Royle (all Hydrocharitaceae), Myriophyllum spicatum L. (Haloragaceae), and Cabomba caroliniana Gray (Cabombaceae). Despite the high probability of invasion, facilitated by vectors and suitable climate, South Africa’s rich indigenous submerged aquatic flora may be preventing the establishment of these submerged invasive species. Studies on the competitive interactions between a common indigenous submerged macrophytes, Lagarosiphon major (Roxb.) (Hydrocharitaceae) and M.spicatum, an invasive native to Eurasia, were conducted to ascertain which conditions influence competitive superiority. High sediment nutrient conditions significantly increased the growth rate and competitive ability of both species, while clay sediments significantly increased the competitive ability of L. major over M. spicatum, but sandy sediments improved the competitive ability of M. spicatum. These results highlighted the dynamic changes in competition between submerged species driven by abiotic factors, but did not take into consideration the effect that herbivory, a biotic factor, could have on competition between the two species. The effect of herbivory by phytophagous insects of submerged plant species has been regarded as negligible. To find out what this effect is, multiple field surveys were undertaken throughout South Africa to find natural enemies of indigenous Lagarosiphon species with the aim of identifying such species, and quantifying their influence on plant growth dynamics. Several new phytophagous species were recorded for the first time. An ephydrid fly, Hydrellia lagarosiphon Deeming (Diptera: Ephydridae) was ascertained to be the most ubiquitous and abundant species associated with L. major in South Africa. The influence of herbivory by this fly on the competitive ability of L. major in the presence of M. spicatum was investigated using an inverse linear model, which showed that herbivory by H. lagarosiphon reduced the competitive ability of L. major by approximately five times in favour of M. spicatum. This study served to highlight the importance of herbivory as a driver of submerged aquatic plant dynamics. Current ecological theory emphasises the importance of investigating beyond plant-herbivore interactions, by including multitrophic interactions in community dynamics. Therefore, the potential of parasitism by a parasitoid wasp, Chaenusa luteostigma sp. n. Achterberg (Hymenoptera: Braconidae: Alysiinae) on H. lagarosiphon to shift the competitive interactions between the two plant species was also examined. The addition of the parasitoid reduced the effect of herbivory by the fly on L. major by half, thereby shifting the competitive balance in favour of L. major over M. spicatum. This study provides valuable insight into a selection of drivers of submerged macrophyte assemblages of South Africa. It highlights the precarious position of South African freshwater systems with regard to the potential invasion by damaging submerged invasive species. It also provides interesting insights into the effect of competition, herbivory and parasitism on the establishment and spread of species within submerged freshwater systems. Understanding the different influences could assist managers and policy makers to make validated decisions ensuring the integrity of South African freshwater systems.
- Full Text:
- Date Issued: 2013
- Authors: Martin, Grant Douglas
- Date: 2013
- Subjects: Freshwater plants -- South Africa Aquatic weeds -- South Africa Invasive plants -- South Africa Freshwater ecology -- South Africa Biotic communities -- South Africa Maximum entropy method Lagarosiphon major -- South Africa Phytophagous insects -- South Africa Hydrellia -- South Africa Parasitoids -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5621 , http://hdl.handle.net/10962/d1004127
- Description: Potentially damaging submerged invasive freshwater macrophytes have been identified in South African freshwater systems, but have received less attention than their floating counterparts. To ascertain the changes and effects that these species may have on macrophyte ecology, an understanding of the drivers of macrophyte assemblages is essential. The aims of this thesis were to investigate select abiotic and biotic factors driving introduction, establishment and spread of submerged macrophytes in South Africa. Surveys on the status of submerged plant species in South Africa were conducted to find out the distribution and diversity of the species present, imported to, and traded in South Africa. Numerous submerged indigenous and invasive macrophyte locality records were collected during field surveys, of which many were first time records. Pet stores and aquarist trading activities were identified as potential vectors for the spread of submerged macrophytes through online surveys and personal interviews. These results highlighted the potential these species have for continuing to enter, and spread within South African water bodies. Maximum Entropy (MAXENT) is a general-purpose method used to predict or infer distributions from incomplete information, and was used here to predict areas suitable for the establishment of five of these invasive macrophytes. Many systems throughout South Africa, particularly those in the subtropical coastal regions, were found to be climatically suitable for the establishment of Elodea canadensis Michx., Egeria densa Planch., Hydrilla verticillata (L.f.) Royle (all Hydrocharitaceae), Myriophyllum spicatum L. (Haloragaceae), and Cabomba caroliniana Gray (Cabombaceae). Despite the high probability of invasion, facilitated by vectors and suitable climate, South Africa’s rich indigenous submerged aquatic flora may be preventing the establishment of these submerged invasive species. Studies on the competitive interactions between a common indigenous submerged macrophytes, Lagarosiphon major (Roxb.) (Hydrocharitaceae) and M.spicatum, an invasive native to Eurasia, were conducted to ascertain which conditions influence competitive superiority. High sediment nutrient conditions significantly increased the growth rate and competitive ability of both species, while clay sediments significantly increased the competitive ability of L. major over M. spicatum, but sandy sediments improved the competitive ability of M. spicatum. These results highlighted the dynamic changes in competition between submerged species driven by abiotic factors, but did not take into consideration the effect that herbivory, a biotic factor, could have on competition between the two species. The effect of herbivory by phytophagous insects of submerged plant species has been regarded as negligible. To find out what this effect is, multiple field surveys were undertaken throughout South Africa to find natural enemies of indigenous Lagarosiphon species with the aim of identifying such species, and quantifying their influence on plant growth dynamics. Several new phytophagous species were recorded for the first time. An ephydrid fly, Hydrellia lagarosiphon Deeming (Diptera: Ephydridae) was ascertained to be the most ubiquitous and abundant species associated with L. major in South Africa. The influence of herbivory by this fly on the competitive ability of L. major in the presence of M. spicatum was investigated using an inverse linear model, which showed that herbivory by H. lagarosiphon reduced the competitive ability of L. major by approximately five times in favour of M. spicatum. This study served to highlight the importance of herbivory as a driver of submerged aquatic plant dynamics. Current ecological theory emphasises the importance of investigating beyond plant-herbivore interactions, by including multitrophic interactions in community dynamics. Therefore, the potential of parasitism by a parasitoid wasp, Chaenusa luteostigma sp. n. Achterberg (Hymenoptera: Braconidae: Alysiinae) on H. lagarosiphon to shift the competitive interactions between the two plant species was also examined. The addition of the parasitoid reduced the effect of herbivory by the fly on L. major by half, thereby shifting the competitive balance in favour of L. major over M. spicatum. This study provides valuable insight into a selection of drivers of submerged macrophyte assemblages of South Africa. It highlights the precarious position of South African freshwater systems with regard to the potential invasion by damaging submerged invasive species. It also provides interesting insights into the effect of competition, herbivory and parasitism on the establishment and spread of species within submerged freshwater systems. Understanding the different influences could assist managers and policy makers to make validated decisions ensuring the integrity of South African freshwater systems.
- Full Text:
- Date Issued: 2013
Dynamic geometry software as a dynamic tool for spatial exploration:
- Holzl, Reinhard, Schäfer, Marc
- Authors: Holzl, Reinhard , Schäfer, Marc
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140871 , vital:37925 , https://hdl.handle.net/10520/EJC146065
- Description: Dynamic Geometry Software (DGS) such as GeoGebra, Geometer's Sketchpad and Cabri Geometry offer a wealth of opportunities for an exploratory style of teaching and learning Mathematics, particularly in the exploration of space and shape. The new Curriculum and Assessment Policy Statement (CAPS) foregrounds the use of spatial skills and properties of shapes and objects "to identify, pose and solve problems creatively and critically" (South Africa. DBE, 2011, p. 9). Although the South African Mathematics curriculum no longer places importance on traditional Euclidean construction by means of straightedge and compass, DGS can nonetheless be used to engage with fundamental ideas relating to geometric shapes, symmetry and transformations. This was the impetus behind encouraging the use of GeoGebra in four township schools in the Grahamstown Education District whose Mathematics teachers participate in an ongoing in-service research and development programme hosted by Rhodes University.
- Full Text:
- Date Issued: 2013
- Authors: Holzl, Reinhard , Schäfer, Marc
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140871 , vital:37925 , https://hdl.handle.net/10520/EJC146065
- Description: Dynamic Geometry Software (DGS) such as GeoGebra, Geometer's Sketchpad and Cabri Geometry offer a wealth of opportunities for an exploratory style of teaching and learning Mathematics, particularly in the exploration of space and shape. The new Curriculum and Assessment Policy Statement (CAPS) foregrounds the use of spatial skills and properties of shapes and objects "to identify, pose and solve problems creatively and critically" (South Africa. DBE, 2011, p. 9). Although the South African Mathematics curriculum no longer places importance on traditional Euclidean construction by means of straightedge and compass, DGS can nonetheless be used to engage with fundamental ideas relating to geometric shapes, symmetry and transformations. This was the impetus behind encouraging the use of GeoGebra in four township schools in the Grahamstown Education District whose Mathematics teachers participate in an ongoing in-service research and development programme hosted by Rhodes University.
- Full Text:
- Date Issued: 2013
Dynamic linkages between monetary policy and the stock market: the case of South Africa
- Authors: Mabitle, Mope
- Date: 2013
- Subjects: Johannesburg Stock Exchange , South African Reserve Bank , Monetary policy -- South Africa
- Language: English
- Type: Thesis , Masters , M Com
- Identifier: vital:11483 , http://hdl.handle.net/10353/d1015290 , Johannesburg Stock Exchange , South African Reserve Bank , Monetary policy -- South Africa
- Description: This study analyses the linkage between monetary policy and the stock market in South Africa using monthly data for the period from 2000 to 2010. It provides an overview of the Johannesburg Stock Exchange and the monetary regimes adopted by the South African Reserve Bank since the 1960s and the interrelation between the monetary variables and the stock market. It also provides a review of literature, both theoretical and empirical on the linkages between the two variables. Based on the review of literature, a Vector Autoregression [VAR] model was chosen as a method of analyzing the relationship between the two variables. The empirical results revealed that there is no long term relationship between the variables, however, in the short-run there is a dynamic relationship between monetary policy and the stock market in South Africa. This implies that innovations in the stock market affect the implementation of monetary policy and vice-versa. The study recommended that monetary authorities should pay attention to the fact that the stock market performance has a great impact on their decision making due to the fact it is greatly affected by repo rates.
- Full Text:
- Date Issued: 2013
- Authors: Mabitle, Mope
- Date: 2013
- Subjects: Johannesburg Stock Exchange , South African Reserve Bank , Monetary policy -- South Africa
- Language: English
- Type: Thesis , Masters , M Com
- Identifier: vital:11483 , http://hdl.handle.net/10353/d1015290 , Johannesburg Stock Exchange , South African Reserve Bank , Monetary policy -- South Africa
- Description: This study analyses the linkage between monetary policy and the stock market in South Africa using monthly data for the period from 2000 to 2010. It provides an overview of the Johannesburg Stock Exchange and the monetary regimes adopted by the South African Reserve Bank since the 1960s and the interrelation between the monetary variables and the stock market. It also provides a review of literature, both theoretical and empirical on the linkages between the two variables. Based on the review of literature, a Vector Autoregression [VAR] model was chosen as a method of analyzing the relationship between the two variables. The empirical results revealed that there is no long term relationship between the variables, however, in the short-run there is a dynamic relationship between monetary policy and the stock market in South Africa. This implies that innovations in the stock market affect the implementation of monetary policy and vice-versa. The study recommended that monetary authorities should pay attention to the fact that the stock market performance has a great impact on their decision making due to the fact it is greatly affected by repo rates.
- Full Text:
- Date Issued: 2013
Dysfunctional facilities management service provision in an outsource environment
- Authors: Otoo, Ernest Kweku
- Date: 2013
- Subjects: Facility management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9725 , http://hdl.handle.net/10948/d1019717
- Full Text:
- Date Issued: 2013
- Authors: Otoo, Ernest Kweku
- Date: 2013
- Subjects: Facility management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9725 , http://hdl.handle.net/10948/d1019717
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- Date Issued: 2013
E-skills training on communal, fixed infrastructure as an activator of personal use of mobile internet
- Gumbo, Sibukelo, Terzoli, Alfredo
- Authors: Gumbo, Sibukelo , Terzoli, Alfredo
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430716 , vital:72710 , https://ieeexplore.ieee.org/abstract/document/6701781
- Description: In the second semester of 2012, training in computer literacy was of-fered in the Dwesa area, in deep rural South Africa, within the footprint of the Siyakhula Living Lab. Training of this nature is essential to make ICT access meaningful in such areas, and avoid wasteful `box drop-ping', unfortunately not uncommon. The training was done using com-munal fixed infrastructure located in schools but, interestingly, activated or deepened the use of mobile intemet among the people that attended the training. This paper contributes on the ongoing debate on whether mobile devices are the one and only solution to ICT access in rural (and peri-urban) poor settings in Africa.
- Full Text:
- Date Issued: 2013
- Authors: Gumbo, Sibukelo , Terzoli, Alfredo
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430716 , vital:72710 , https://ieeexplore.ieee.org/abstract/document/6701781
- Description: In the second semester of 2012, training in computer literacy was of-fered in the Dwesa area, in deep rural South Africa, within the footprint of the Siyakhula Living Lab. Training of this nature is essential to make ICT access meaningful in such areas, and avoid wasteful `box drop-ping', unfortunately not uncommon. The training was done using com-munal fixed infrastructure located in schools but, interestingly, activated or deepened the use of mobile intemet among the people that attended the training. This paper contributes on the ongoing debate on whether mobile devices are the one and only solution to ICT access in rural (and peri-urban) poor settings in Africa.
- Full Text:
- Date Issued: 2013
Ecological niche modeling of the invasive potential of Nile tilapia Oreochromis niloticus in African river systems: concerns and implications for the conservation of indigenous congenerics
- Zengeya, Tsungai A, Robertson, Mark P, Booth, Anthony J, Chimimba, Christian T
- Authors: Zengeya, Tsungai A , Robertson, Mark P , Booth, Anthony J , Chimimba, Christian T
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124341 , vital:35596 , https://doi.10.1007/s10530-012-0386-7
- Description: This study applied ecological niche models to determine the potential invasive range of Nile tilapia, Oreochromis niloticus, with a particular focus on river systems in southern Africa where it is now established and spreading. Computational tools such as niche models are useful in predicting the potential range of invasive species, but there are limitations to their application. In particular, models trained on native records may fail to predict the full extent of an invasion. This failure is often attributed to changes in either the niche of the invading species or the variables used to develop the models. In this study, we therefore evaluated the differences in the predictive power of models trained with different environmental variables, the effect of species range (native vs. introduced) on model performance and assessed whether or not there is evidence suggestive of a niche shift in Nile tilapia following its introduction. Niche models were constructed using Maxent and the degree of niche similarity was assessed using Schoener‘s index. Null models were used to test for significance. Model performance and niche conservatism varied significantly with variable selection and species range. This indicates that the environmental conditions available to Nile tilapia in its native and introduced ranges are not congruent. Nile tilapia exhibited broad invasive potential over most of southern Africa that overlaps the natural range of endemic congenerics. Of particular concern are areas which are free of exotic species but are now vulnerable due to the promotion of fish introductions mainly for aquaculture and sport fishing.
- Full Text:
- Date Issued: 2013
- Authors: Zengeya, Tsungai A , Robertson, Mark P , Booth, Anthony J , Chimimba, Christian T
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124341 , vital:35596 , https://doi.10.1007/s10530-012-0386-7
- Description: This study applied ecological niche models to determine the potential invasive range of Nile tilapia, Oreochromis niloticus, with a particular focus on river systems in southern Africa where it is now established and spreading. Computational tools such as niche models are useful in predicting the potential range of invasive species, but there are limitations to their application. In particular, models trained on native records may fail to predict the full extent of an invasion. This failure is often attributed to changes in either the niche of the invading species or the variables used to develop the models. In this study, we therefore evaluated the differences in the predictive power of models trained with different environmental variables, the effect of species range (native vs. introduced) on model performance and assessed whether or not there is evidence suggestive of a niche shift in Nile tilapia following its introduction. Niche models were constructed using Maxent and the degree of niche similarity was assessed using Schoener‘s index. Null models were used to test for significance. Model performance and niche conservatism varied significantly with variable selection and species range. This indicates that the environmental conditions available to Nile tilapia in its native and introduced ranges are not congruent. Nile tilapia exhibited broad invasive potential over most of southern Africa that overlaps the natural range of endemic congenerics. Of particular concern are areas which are free of exotic species but are now vulnerable due to the promotion of fish introductions mainly for aquaculture and sport fishing.
- Full Text:
- Date Issued: 2013