Analysis of maximum power point tracking data for obtaining photovoltaic parameters
- Authors: Chitura, Anesu Godfrey
- Date: 2020
- Subjects: Photovoltaic power system
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/18576 , vital:42610
- Description: As a standard, photovoltaic (PV) modules are rated by the use of standard test conditions (STC). Such details entail current and voltage (I-V) measurements for modules under an irradiance of 1000 W/m2 an air mass ration of 1.5 global spectrum and 25˚C cell temperature. Outdoor weather conditions continuously vary with time and from one location to the other. This further offset the expected operational power outputs as outdoor conditions are generally characterized by high cell temperatures. The technology one uses will also complicate the power output prediction since different module technologies respond to these outdoor conditions differently. I-V tracers are able to measure the full I-V curve of the module thus can give the operational PV parameters at any given time. However, these tracers are sold at exorbitant prices and they require skilled personnel in order to operate them. Most if not all tracers require isolation of the module under test thereby disrupting the power production function of the module._________________________________________________________________________________________________________________________________________ In this study a method to obtain photovoltaic (PV) parameters using the maximum power point tracking (MPPT) data is presented and tested under natural outdoor conditions. The method features a customized data acquisition system (DAS) designed for the measurement and storage of meteorological and MPPT data. The DAS is capable of extracting parameters from any combination of modules with an open circuit voltage 〖(V〗_oc) less than or equal to 120 Volts and a short circuit current 〖(I〗_sc) of 100 Amps. The system used is capable of extracting MPPT data using a reliable, improved storage and a programmable data logger. In order to match the sampling operational speeds of internal charge controller switches a computer interfaced Peripheral Component Interconnect (PCI) card was also used. Data collection and characterization of the MPPT data was done in such a way that the power generation process remained uninterrupted throughout the whole process. The regression nonlinear least squares method was used to fit MPPT crests and obtain the knee part of the I-V curve. This was then extrapolated to obtain the full I-V curve, which then produces the operational PV parameters. The resultant parameters from the characterization process were logged and accessible at any time. The end result was a method that can be incorporated within a charge controller for quick, hands-free PV parameter extraction, using only the MPPT scanned data.
- Full Text:
- Date Issued: 2020
- Authors: Chitura, Anesu Godfrey
- Date: 2020
- Subjects: Photovoltaic power system
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/18576 , vital:42610
- Description: As a standard, photovoltaic (PV) modules are rated by the use of standard test conditions (STC). Such details entail current and voltage (I-V) measurements for modules under an irradiance of 1000 W/m2 an air mass ration of 1.5 global spectrum and 25˚C cell temperature. Outdoor weather conditions continuously vary with time and from one location to the other. This further offset the expected operational power outputs as outdoor conditions are generally characterized by high cell temperatures. The technology one uses will also complicate the power output prediction since different module technologies respond to these outdoor conditions differently. I-V tracers are able to measure the full I-V curve of the module thus can give the operational PV parameters at any given time. However, these tracers are sold at exorbitant prices and they require skilled personnel in order to operate them. Most if not all tracers require isolation of the module under test thereby disrupting the power production function of the module._________________________________________________________________________________________________________________________________________ In this study a method to obtain photovoltaic (PV) parameters using the maximum power point tracking (MPPT) data is presented and tested under natural outdoor conditions. The method features a customized data acquisition system (DAS) designed for the measurement and storage of meteorological and MPPT data. The DAS is capable of extracting parameters from any combination of modules with an open circuit voltage 〖(V〗_oc) less than or equal to 120 Volts and a short circuit current 〖(I〗_sc) of 100 Amps. The system used is capable of extracting MPPT data using a reliable, improved storage and a programmable data logger. In order to match the sampling operational speeds of internal charge controller switches a computer interfaced Peripheral Component Interconnect (PCI) card was also used. Data collection and characterization of the MPPT data was done in such a way that the power generation process remained uninterrupted throughout the whole process. The regression nonlinear least squares method was used to fit MPPT crests and obtain the knee part of the I-V curve. This was then extrapolated to obtain the full I-V curve, which then produces the operational PV parameters. The resultant parameters from the characterization process were logged and accessible at any time. The end result was a method that can be incorporated within a charge controller for quick, hands-free PV parameter extraction, using only the MPPT scanned data.
- Full Text:
- Date Issued: 2020
The impact of perceived ethical leadership on employees’ predisposition to behave ethically: a case study within a South African-based financial institution
- Authors: Rudzani, Magau
- Date: 2019
- Subjects: Leadership -- Moral and ethical aspects , Leadership Business ethics Ethics
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/40768 , vital:36234
- Description: Ethical leaders consistently set ethical principles within the institution and act in accordance with them; hence, leaders should be a key source of ethical guidance for employees. As the business world is constantly evolving, leaders increasingly are required to ethically lead across different sectors. Current literature on ethical leadership and its influence of employees reflects mostly a Western, European and Asian-based private-sector perspective, pointing toward a compliance-oriented understanding of ethical and unethical leadership. This study examined how perceived ethical orientation of a leader has an impact on employees’ predisposition to behave ethically within a South African context. Qualitative data was collected as the study adopted the interpretivist paradigm, which made it easier for participants to use descriptive words and qualifying statements to express the level of influence their leaders had on their ethical orientation. The target population of the study included all staff of the institution; and participants were chosen using the purposive sampling method. Data was collected from 12 employees using semi-structure interviews. Thereafter, thematic analysis was used to identify and organise participants’ experiences into themes that established the basis for the study findings. These findings confirmed that perceived leader ethical orientation has an impact on employees’ predisposition to behave ethically. The study found that ethical leaders had a track record of being consistent, honest, trustworthy, truthful and credible, and being a role model. In addition, the study also found that unethical leaders are easily identifiable by their perpetual inability to uphold principles of integrity, reliability, rationality, and social justice and fairness. The researcher concluded that the moral identity of the leader has an influence on followers’ predisposition to behave ethically or unethically. The implications of this study are that ethical morals, by their very nature, are transferable from one person to the other and ethical leadership was one antecedent through which this transfer takes place. However, ethical leadership was not the only apparatus that influenced employees’ ethical predisposition and these afford opportunities for future research.
- Full Text:
- Date Issued: 2019
- Authors: Rudzani, Magau
- Date: 2019
- Subjects: Leadership -- Moral and ethical aspects , Leadership Business ethics Ethics
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/40768 , vital:36234
- Description: Ethical leaders consistently set ethical principles within the institution and act in accordance with them; hence, leaders should be a key source of ethical guidance for employees. As the business world is constantly evolving, leaders increasingly are required to ethically lead across different sectors. Current literature on ethical leadership and its influence of employees reflects mostly a Western, European and Asian-based private-sector perspective, pointing toward a compliance-oriented understanding of ethical and unethical leadership. This study examined how perceived ethical orientation of a leader has an impact on employees’ predisposition to behave ethically within a South African context. Qualitative data was collected as the study adopted the interpretivist paradigm, which made it easier for participants to use descriptive words and qualifying statements to express the level of influence their leaders had on their ethical orientation. The target population of the study included all staff of the institution; and participants were chosen using the purposive sampling method. Data was collected from 12 employees using semi-structure interviews. Thereafter, thematic analysis was used to identify and organise participants’ experiences into themes that established the basis for the study findings. These findings confirmed that perceived leader ethical orientation has an impact on employees’ predisposition to behave ethically. The study found that ethical leaders had a track record of being consistent, honest, trustworthy, truthful and credible, and being a role model. In addition, the study also found that unethical leaders are easily identifiable by their perpetual inability to uphold principles of integrity, reliability, rationality, and social justice and fairness. The researcher concluded that the moral identity of the leader has an influence on followers’ predisposition to behave ethically or unethically. The implications of this study are that ethical morals, by their very nature, are transferable from one person to the other and ethical leadership was one antecedent through which this transfer takes place. However, ethical leadership was not the only apparatus that influenced employees’ ethical predisposition and these afford opportunities for future research.
- Full Text:
- Date Issued: 2019
Assessment of the long-term response to rehabilitation of two wetlands in KwaZulu-Natal, South Africa
- Authors: Cowden, Craig
- Date: 2018
- Subjects: Wetlands -- South Africa -- KwaZulu-Natal Wetland restoration -- South Africa -- KwaZulu-Natal Wetland management -- South Africa -- KwaZulu-Natal Wetland conservation -- South Africa -- KwaZulu-Natal Wetland ecology -- South Africa -- KwaZulu-Natal Ecosystem management -- South Africa -- KwaZulu-Natal
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60606 , vital:27802
- Description: Assessing the outputs and outcomes of wetland rehabilitation activities is recognised by the 'Working for Wetlands' programme in South Africa as important, but to date has been limited. An assessment of the ecological outcomes and the structural outputs of the Working for Wetlands rehabilitation implemented in the Killarney and Kruisfontein wetlands, KwaZulu-Natal, in 2005 was undertaken. The assessment of outcomes included an evaluation of the changes in terms of ecological integrity and the supply of ecosystem services, using WET-Health and WET- EcoServices assessment techniques respectively, and vegetation composition. Improvements in hydrological and geomorphic integrity were recorded in both wetlands, resulting in improved ecosystem services delivery. However, investigation of vegetation composition using the Wetland Index Value and Floristic Quality Assessment Index showed that, seven years after rehabilitation, KiNamey's vegetation composition had improved, but Kruisfontein's vegetation was still largely dominated by pioneer species and appeared to be stable, but in a severely transformed state. The response of these wetlands has shown that sites for rehabilitation should be screened before work begins, and wetlands requiring intensive management of vegetation recovery should be assessed in terms of the objectives and the anticipated benefits of the project. The assessment of the outputs included an evaluation of structural integrity, survival and cost- effectiveness. Limited issues, mostly relating to deviations from the designs during construction, were identified with regards to the structural outputs at each of the wetlands. However, the spreader canals at both Killarney and Kruisfontein wetlands were not functioning as intended and concentrated flows from the spreader canals were evident in both wetlands. The use of spreader canals should therefore be carefully planned and implemented for future wetland rehabilitation projects. Consideration of ZAR per hectare equivalent re-instated/secured provided a useful initial means of determining the cost-effectiveness of the wetland rehabilitation. However, additional factors need to be considered, such as, the nature of the rehabilitation activities, the type and size of the problem being addressed, rehabilitation of priority wetlands, limitations imposed by funders, and risks that need to be addressed by the rehabilitation strategy. Furthermore, the evaluation of the Killarney and Kruisfontein wetlands highlighted the need to revise the Water Research Commission's Wetland Management Series, especially those documents or guidelines relating to rehabilitation planning (WET-RehabPlan), interventions (WET-RehabMethods), and monitoring and evaluation (WET-RehabEvaluate).
- Full Text:
- Date Issued: 2018
- Authors: Cowden, Craig
- Date: 2018
- Subjects: Wetlands -- South Africa -- KwaZulu-Natal Wetland restoration -- South Africa -- KwaZulu-Natal Wetland management -- South Africa -- KwaZulu-Natal Wetland conservation -- South Africa -- KwaZulu-Natal Wetland ecology -- South Africa -- KwaZulu-Natal Ecosystem management -- South Africa -- KwaZulu-Natal
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60606 , vital:27802
- Description: Assessing the outputs and outcomes of wetland rehabilitation activities is recognised by the 'Working for Wetlands' programme in South Africa as important, but to date has been limited. An assessment of the ecological outcomes and the structural outputs of the Working for Wetlands rehabilitation implemented in the Killarney and Kruisfontein wetlands, KwaZulu-Natal, in 2005 was undertaken. The assessment of outcomes included an evaluation of the changes in terms of ecological integrity and the supply of ecosystem services, using WET-Health and WET- EcoServices assessment techniques respectively, and vegetation composition. Improvements in hydrological and geomorphic integrity were recorded in both wetlands, resulting in improved ecosystem services delivery. However, investigation of vegetation composition using the Wetland Index Value and Floristic Quality Assessment Index showed that, seven years after rehabilitation, KiNamey's vegetation composition had improved, but Kruisfontein's vegetation was still largely dominated by pioneer species and appeared to be stable, but in a severely transformed state. The response of these wetlands has shown that sites for rehabilitation should be screened before work begins, and wetlands requiring intensive management of vegetation recovery should be assessed in terms of the objectives and the anticipated benefits of the project. The assessment of the outputs included an evaluation of structural integrity, survival and cost- effectiveness. Limited issues, mostly relating to deviations from the designs during construction, were identified with regards to the structural outputs at each of the wetlands. However, the spreader canals at both Killarney and Kruisfontein wetlands were not functioning as intended and concentrated flows from the spreader canals were evident in both wetlands. The use of spreader canals should therefore be carefully planned and implemented for future wetland rehabilitation projects. Consideration of ZAR per hectare equivalent re-instated/secured provided a useful initial means of determining the cost-effectiveness of the wetland rehabilitation. However, additional factors need to be considered, such as, the nature of the rehabilitation activities, the type and size of the problem being addressed, rehabilitation of priority wetlands, limitations imposed by funders, and risks that need to be addressed by the rehabilitation strategy. Furthermore, the evaluation of the Killarney and Kruisfontein wetlands highlighted the need to revise the Water Research Commission's Wetland Management Series, especially those documents or guidelines relating to rehabilitation planning (WET-RehabPlan), interventions (WET-RehabMethods), and monitoring and evaluation (WET-RehabEvaluate).
- Full Text:
- Date Issued: 2018
Students’ intentions and attitudes towards using Information and Communication Technology (ICT) for the purpose of counselling.
- Authors: Dlaza, Zikhona
- Date: 2018
- Subjects: Internet -- Psychological aspects Internet users -- Psychology
- Language: English
- Type: Thesis , Masters , MSoc. Sci (Psychology)
- Identifier: http://hdl.handle.net/10353/17553 , vital:41090
- Description: Information Communication Technology (ICT) is becoming popular especially within a university campus setting not only as a learning tool but also for the purpose of communication. Internationally there is an acknowledgement of the popularity of ICT in delivering mental health services. This study is built on that premise which indicates that ICT could serve as a viable tool for counselling interventions within a university setting. However, limited research has been done in this area and conflicting results have been reported especially related to gender. This study therefore aimed at exploring the intentions and attitudes of male and female students towards using ICT for counselling at a South African university. A quantitative research approach was employed to collect and analyze data. Data was collected amongst students using self-administered questionnaires with a sample of 266 (N = 266) respondents. Descriptive and inferential statistics were employed. The main findings of the study indicate that students have an intention to seek psychological help through the use of ICT counselling, which consequently positively influenced attitudes towards the utilization of ICT counselling. Results further indicate that gender and age differences amongst university students is significantly related to the intention to use ICT counselling. The information generated from this study has contributed to the limited body of literature on ICT in counselling psychology, more specifically in a university setting in South Africa. Overall, it encourages critical reflection on modern psychological practice to meet student’s needs.
- Full Text:
- Date Issued: 2018
- Authors: Dlaza, Zikhona
- Date: 2018
- Subjects: Internet -- Psychological aspects Internet users -- Psychology
- Language: English
- Type: Thesis , Masters , MSoc. Sci (Psychology)
- Identifier: http://hdl.handle.net/10353/17553 , vital:41090
- Description: Information Communication Technology (ICT) is becoming popular especially within a university campus setting not only as a learning tool but also for the purpose of communication. Internationally there is an acknowledgement of the popularity of ICT in delivering mental health services. This study is built on that premise which indicates that ICT could serve as a viable tool for counselling interventions within a university setting. However, limited research has been done in this area and conflicting results have been reported especially related to gender. This study therefore aimed at exploring the intentions and attitudes of male and female students towards using ICT for counselling at a South African university. A quantitative research approach was employed to collect and analyze data. Data was collected amongst students using self-administered questionnaires with a sample of 266 (N = 266) respondents. Descriptive and inferential statistics were employed. The main findings of the study indicate that students have an intention to seek psychological help through the use of ICT counselling, which consequently positively influenced attitudes towards the utilization of ICT counselling. Results further indicate that gender and age differences amongst university students is significantly related to the intention to use ICT counselling. The information generated from this study has contributed to the limited body of literature on ICT in counselling psychology, more specifically in a university setting in South Africa. Overall, it encourages critical reflection on modern psychological practice to meet student’s needs.
- Full Text:
- Date Issued: 2018
The prospects of commercialising small-scale chicken production in Buffalo City metropolitan municipality, Eastern Cape province, South Africa
- Authors: Seti, Thembalethu Macdonald
- Date: 2017
- Subjects: Farms, Small -- South Africa -- Eastern Cape Poultry -- Breeding -- South Africa -- Eastern Cape Chicken industry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/15244 , vital:40257
- Description: The aim of this study is to explore the prospects of commercialising small-scale chicken production in Buffalo City Metropolitan Municipality, Eastern Cape. In the attempt of exploring these prospects, the researcher sought to understand socio-economic characteristics of small-scale chicken farmers, describe the small-scale chicken enterprise, and determine farmer’s level of commercialisation and factors influencing the farmer’s commercialisation level. Stratified random sampling was used to select 99 participants in the study area. The sampled participants constituted small-scale chicken farmers that were supported by government projects and farmers that were not part of any government support. Descriptive statistics, Household Commercialization Index (HCI) and Multinomial Regression model were used to analyse data and bring meaning to it. The results of the study signify that most of the farmers (66percent) are subsistence oriented, meaning most of their produce is consumed within the household and about 40percent are semi-commercial and only 7percent are at full commercialization meaning they only produce for the market. The result also showed that access to extension services (p<0.03), gender (p<0.03) household size (permanent family members) (p<0.01), transport cost (p<0.04), farming experience (p<0.02, grades and standards (p<0.01), production machines (p<0.05), and distance to the market (p<0.05) were the major determinants influencing output commercialization in the study area. The major constraints to production identified and prioritized by farmers were lack of feed, disease outbreaks, high mortality rate and theft. Based on the study results, to bring about the prospects of commercialising small-scale chicken, government should consistently supply extension officers, government investment in poultry machines and transport is also recommended. In terms of further research, the study suggests that research on profitability of small-scale chicken production would yield immense insights for policy development.
- Full Text:
- Date Issued: 2017
- Authors: Seti, Thembalethu Macdonald
- Date: 2017
- Subjects: Farms, Small -- South Africa -- Eastern Cape Poultry -- Breeding -- South Africa -- Eastern Cape Chicken industry -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/15244 , vital:40257
- Description: The aim of this study is to explore the prospects of commercialising small-scale chicken production in Buffalo City Metropolitan Municipality, Eastern Cape. In the attempt of exploring these prospects, the researcher sought to understand socio-economic characteristics of small-scale chicken farmers, describe the small-scale chicken enterprise, and determine farmer’s level of commercialisation and factors influencing the farmer’s commercialisation level. Stratified random sampling was used to select 99 participants in the study area. The sampled participants constituted small-scale chicken farmers that were supported by government projects and farmers that were not part of any government support. Descriptive statistics, Household Commercialization Index (HCI) and Multinomial Regression model were used to analyse data and bring meaning to it. The results of the study signify that most of the farmers (66percent) are subsistence oriented, meaning most of their produce is consumed within the household and about 40percent are semi-commercial and only 7percent are at full commercialization meaning they only produce for the market. The result also showed that access to extension services (p<0.03), gender (p<0.03) household size (permanent family members) (p<0.01), transport cost (p<0.04), farming experience (p<0.02, grades and standards (p<0.01), production machines (p<0.05), and distance to the market (p<0.05) were the major determinants influencing output commercialization in the study area. The major constraints to production identified and prioritized by farmers were lack of feed, disease outbreaks, high mortality rate and theft. Based on the study results, to bring about the prospects of commercialising small-scale chicken, government should consistently supply extension officers, government investment in poultry machines and transport is also recommended. In terms of further research, the study suggests that research on profitability of small-scale chicken production would yield immense insights for policy development.
- Full Text:
- Date Issued: 2017
A bitcoin framework : an alternative payment system for marginalized areas of South Africa using low-end mobile phones
- Authors: Dlamini, Nelisiwe Peaceness
- Date: 2016
- Subjects: Electronic funds transfers -- South Africa Bitcoin -- South Africa Mobile commerce -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/11884 , vital:39115
- Description: The emergence of the cryptocurrency Bitcoin, has invoked the need for developing financial systems that can be used to transfer digital value. This would serve as a solution to developing countries especially the challenged ones, when it comes to accommodating the financial needs of the disadvantaged people. Moreover, it facilitates access to financial services to allow them to transact with ease. Numerous companies have taken advantage of the prevalence of mobile phones and introduced financial platforms to provide financial inclusion to disadvantaged people. Financial institutions and Mobile Network Operators (MNO) have developed platforms such as cell phone banking services, mobile money, mobile wallets, and electronic wallets that can be used to provide affordable financial services. Although this is the case, alternative platforms that are affordable and accessible through mobile phones are still required. Therefore, this study proposes a Bitcoin framework that can be used as an alternative platform through low-end mobile phones to provide access to financial services to the disadvantaged people in marginalized areas. To prove the concept of the proposed Bitcoin framework, a Mobile Bitcoin Wallet System (MBWS) prototype was developed, which allows a person using a low-end mobile phone with no intervening technology such as Internet or Bluetooth, to access a Bitcoin wallet by sending a Short Message Service (SMS). This enables Bitcoin to be accessed more easily and affordably by the people. Thus the developed prototype conceptualizes an alternative payment system or a payment method that can augment the existing payment methods. The MBWS is evaluated to assess if it can offer the services that other platforms offer by being compared to a cell-phone banking service. It was deployed on a computer connected to the Internet to enable a connection to the Bitcoin network and access to the blockchain which records all the transactions that take place in Bitcoin. Although this system provides access to the Bitcoin wallet, for it to be applied to areas where people require an alternative payment system, it still needs to be enhanced for such use. This includes scaling the system and adding more functions to it.
- Full Text:
- Date Issued: 2016
- Authors: Dlamini, Nelisiwe Peaceness
- Date: 2016
- Subjects: Electronic funds transfers -- South Africa Bitcoin -- South Africa Mobile commerce -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/11884 , vital:39115
- Description: The emergence of the cryptocurrency Bitcoin, has invoked the need for developing financial systems that can be used to transfer digital value. This would serve as a solution to developing countries especially the challenged ones, when it comes to accommodating the financial needs of the disadvantaged people. Moreover, it facilitates access to financial services to allow them to transact with ease. Numerous companies have taken advantage of the prevalence of mobile phones and introduced financial platforms to provide financial inclusion to disadvantaged people. Financial institutions and Mobile Network Operators (MNO) have developed platforms such as cell phone banking services, mobile money, mobile wallets, and electronic wallets that can be used to provide affordable financial services. Although this is the case, alternative platforms that are affordable and accessible through mobile phones are still required. Therefore, this study proposes a Bitcoin framework that can be used as an alternative platform through low-end mobile phones to provide access to financial services to the disadvantaged people in marginalized areas. To prove the concept of the proposed Bitcoin framework, a Mobile Bitcoin Wallet System (MBWS) prototype was developed, which allows a person using a low-end mobile phone with no intervening technology such as Internet or Bluetooth, to access a Bitcoin wallet by sending a Short Message Service (SMS). This enables Bitcoin to be accessed more easily and affordably by the people. Thus the developed prototype conceptualizes an alternative payment system or a payment method that can augment the existing payment methods. The MBWS is evaluated to assess if it can offer the services that other platforms offer by being compared to a cell-phone banking service. It was deployed on a computer connected to the Internet to enable a connection to the Bitcoin network and access to the blockchain which records all the transactions that take place in Bitcoin. Although this system provides access to the Bitcoin wallet, for it to be applied to areas where people require an alternative payment system, it still needs to be enhanced for such use. This includes scaling the system and adding more functions to it.
- Full Text:
- Date Issued: 2016
An assessment of quality, class and grade of service (QoS, CoS and GoS) over worldwide interoperability for microwave access (WiMax) networks through performance evaluation of bandwidth
- Authors: Nomnga, Phumzile
- Date: 2016
- Subjects: Wireless communication systems Wireless LANs -- Standards Broadband communication systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/8033 , vital:31481
- Description: The Dwesa WiMAX network provides broadband communications over wireless connectivity for various types of multimedia traffic, such as emailing, browsing, VoIP, file transfer, etc. to the community members. The community members of Dwesa use schools’ computer labs to access the network and generate the aforementioned multimedia packets on dedicated timeslots and thus cause network congestion during such timeslots. Against this background, WiMAX implementation has faced several challenges in living up to its objectives in RMAs. Quality of Service (QoS) degradation as a result of high traffic demands remains one of the challenges thwarting WiMAX implementation. The GoS is also bound to get compromised as connectivity demands arise consistently with more subscribers connecting to the network, making it difficult to measure the success a subscriber is expected to have in accessing the network. The CoS and SchedType play a significant role in the redistribution of the available bandwidth to all bandwidth requests. This research project exploits this avenue to assess the resultant degradation of QoS and GoS caused by the inconsistent availability of bandwidth as redistributed by the CoS combination with a SchedType. The four CoS which are, namely, the UGS, rtPS, nrtPS and BE were implemented with the different SchedTypes, namely, MBQOS, FCFS and rtPS. Although the implementation process was conducted in a simulated environment using NS-3, the simulated network emulated the network setup implemented in Dwesa. The outcomes of the implementation suggests that certain combinations of the CoS’s with SchedTypes can lead to degradation of QoS whilst some combinations can redistribute the available bandwidth to ensure the provisioning of guaranteed QoS.
- Full Text:
- Date Issued: 2016
- Authors: Nomnga, Phumzile
- Date: 2016
- Subjects: Wireless communication systems Wireless LANs -- Standards Broadband communication systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/8033 , vital:31481
- Description: The Dwesa WiMAX network provides broadband communications over wireless connectivity for various types of multimedia traffic, such as emailing, browsing, VoIP, file transfer, etc. to the community members. The community members of Dwesa use schools’ computer labs to access the network and generate the aforementioned multimedia packets on dedicated timeslots and thus cause network congestion during such timeslots. Against this background, WiMAX implementation has faced several challenges in living up to its objectives in RMAs. Quality of Service (QoS) degradation as a result of high traffic demands remains one of the challenges thwarting WiMAX implementation. The GoS is also bound to get compromised as connectivity demands arise consistently with more subscribers connecting to the network, making it difficult to measure the success a subscriber is expected to have in accessing the network. The CoS and SchedType play a significant role in the redistribution of the available bandwidth to all bandwidth requests. This research project exploits this avenue to assess the resultant degradation of QoS and GoS caused by the inconsistent availability of bandwidth as redistributed by the CoS combination with a SchedType. The four CoS which are, namely, the UGS, rtPS, nrtPS and BE were implemented with the different SchedTypes, namely, MBQOS, FCFS and rtPS. Although the implementation process was conducted in a simulated environment using NS-3, the simulated network emulated the network setup implemented in Dwesa. The outcomes of the implementation suggests that certain combinations of the CoS’s with SchedTypes can lead to degradation of QoS whilst some combinations can redistribute the available bandwidth to ensure the provisioning of guaranteed QoS.
- Full Text:
- Date Issued: 2016
An investigation into how participation in science expo projects influences grade 9 learners’ dispositions towards science learning: a case study
- Authors: Musekiwa, Beatrice K
- Date: 2016
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/1430 , vital:20056
- Description: There has been increasing participation of learners from disadvantaged backgrounds in competitive events like the Eskom Science Expo over the past few years. It is against this backdrop that this study sought to find out how some grade 9 learners’ participation in science expo projects influences their disposition towards science. In the context of this study, disposition refers to how learners view themselves in relation to science learning as a result of participating in science expos. The study is underpinned by an interpretative paradigm and I made use of a qualitative case study. My research participants were five grade 9 learners from two secondary schools in Grahamstown in the Eastern Cape Province of South Africa. I used observations, semistructured interviews and learners’ journals for my data collection. To analyse the data I used the inductive approach where I made use of themes emerging from the data. The social learning theory described by Vygotsky (1978) is the guiding theory in the research with a focus on mediation of learning and the zone of proximal development (ZPD). The main findings from my study were that indeed participation in science expos does influence the disposition of learners towards science among the grade 9 learners. I also found an improved understanding of scientific concepts as the learners interacted with science in everyday and familiar contexts. Lastly, doing projects that are close to learners’ interests resulted in them enjoying doing science more. The learners’ science expo projects contribution to the Grahamstown community is of no small value, as has already been seen by the achievement of previous participants. The current group is already showing their impact and influence of the science–expo project involvement in terms of their performance in their classrooms and in their awareness of their role as young ‘scientists’. I therefore recommend that more learners be encouraged to take part in such projects as the science-expo projects not only improve learners’ understanding of the subject matter but also encourages a positive shift in their attitude towards science learning. It also enhances their understanding by allowing the young learners to interact with their environment to find solutions to problems that the community might be faced with, for example, water shortages and sustainable development initiations like gardening and the proper use of naturally acquired water resources.
- Full Text:
- Date Issued: 2016
- Authors: Musekiwa, Beatrice K
- Date: 2016
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/1430 , vital:20056
- Description: There has been increasing participation of learners from disadvantaged backgrounds in competitive events like the Eskom Science Expo over the past few years. It is against this backdrop that this study sought to find out how some grade 9 learners’ participation in science expo projects influences their disposition towards science. In the context of this study, disposition refers to how learners view themselves in relation to science learning as a result of participating in science expos. The study is underpinned by an interpretative paradigm and I made use of a qualitative case study. My research participants were five grade 9 learners from two secondary schools in Grahamstown in the Eastern Cape Province of South Africa. I used observations, semistructured interviews and learners’ journals for my data collection. To analyse the data I used the inductive approach where I made use of themes emerging from the data. The social learning theory described by Vygotsky (1978) is the guiding theory in the research with a focus on mediation of learning and the zone of proximal development (ZPD). The main findings from my study were that indeed participation in science expos does influence the disposition of learners towards science among the grade 9 learners. I also found an improved understanding of scientific concepts as the learners interacted with science in everyday and familiar contexts. Lastly, doing projects that are close to learners’ interests resulted in them enjoying doing science more. The learners’ science expo projects contribution to the Grahamstown community is of no small value, as has already been seen by the achievement of previous participants. The current group is already showing their impact and influence of the science–expo project involvement in terms of their performance in their classrooms and in their awareness of their role as young ‘scientists’. I therefore recommend that more learners be encouraged to take part in such projects as the science-expo projects not only improve learners’ understanding of the subject matter but also encourages a positive shift in their attitude towards science learning. It also enhances their understanding by allowing the young learners to interact with their environment to find solutions to problems that the community might be faced with, for example, water shortages and sustainable development initiations like gardening and the proper use of naturally acquired water resources.
- Full Text:
- Date Issued: 2016
Gradient high performance liquid chromatographic method for the simultaneous analysis of efavirenz, emtricitabine and tenofovir
- Authors: Koekemoer, Sonya Mariana
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10962/54679 , vital:26599
- Description: In 2014, approximately 6.8 million people in South Africa were HIV-positive, and the majority of those affected are aged 15 or older. A fixed-dose combination (FDC) antiretroviral (ARV) dosage form containing one non-nucleotide reverse transcriptase inhibitor (efavirenz) and two nucleotide reverse transcriptase inhibitors (emtricitabine and tenofovir) was licensed in South Africa in April 2013. New consolidated guidelines for HIV management and prevention of mother to child transmission (PMTCT) were published by the South African Department of Health in December 2014 and the FDC is now the recommended first-line treatment for HIV-positive patients. According to these guidelines all such people aged 15 and older, and weighing more than 40 kg, with a CD4 count of ≤ 500/ μl will be eligible for antiretroviral therapy (ART) using the FDC. In addition every pregnant and breastfeeding woman is eligible for lifelong ART regardless of CD4 count and EFV can be used as first-line treatment for pregnant women regardless of the length of gestation state of the pregnancy at that time. The use of this simplified regime is likely to promote much needed and improved adherence to therapy. An investigation into the development of a stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method for the simultaneous quantitation of EFV, FTC and TNF was undertaken. Isocratic HPLC analysis was found to be unsuitable due to the highly polar FTC molecule eluting in the void. Therefore a gradient HPLC method was developed and validated. The method was validated according to the International Conference on Harmonisation, now known as International Council for Harmonization (ICH). Correlation coefficients > 0.999 were obtained for each assessment of linearity and FTC, TNF and EFV are linear in the range 0.4-40 μg/ml, 0.6-60 μg/ml and 1.2-120 μg/ml. The equation of the best-fit least squares regression lines for FTC, TNF and EFV were y = 0.0191x+0.0007, y = 0.0163x+0.0116 and y = 0.01x+0.016, respectively. The method is accurate as the y-intercept was < 2% of the detector response for all ARV, and the method is precise in terms of intra- and inter-assay precision as all % RSD < 2%. The stability-indicating nature of the method was demonstrated under acidic, alkaline and oxidative stress in addition to UV exposure and elevated temperatures, and the individual chromatograms were overlaid using Empower® 3 Software to establish whether there was interference with the peaks of interest. The forced degradation studies demonstrated the selectivity of the method for the ARV compounds. The method was applied to assay and in vitro dissolution studies of commercially available tablets. The amount of each active ingredient released from Atripla® was determined and compared to the amount of each drug released from Aspen Efavirenz® and Truvada® (a combination of FTC and TNF). The percent FTC released from Atripla® and Truvada® was similar based on the acceptance criteria for immediate-release BCS class 1 compounds. Statistical analysis was undertaken to compare the dissolution profiles of FTC, TNF and EFV. The percent of these compounds released in these studies indicate that bioequivalence testing would be required to declare these products interchangeable. The validated RP-HPLC and in vitro dissolution test method are suitable for routine quality control testing of solid oral dosage forms containing EFV, FTC and TNF, and as the dissolution method can discriminate between different formulations of the same molecule, these tools can also be used for analysis during formulation development studies. The method is not suitable for the analysis of the ARV plasma due to lack of sensitivity and an inability to quantitate the compounds at the required concentration levels. The use of HPLC with mass spectroscopy for quantitation would enhance the sensitivity of the method and may eliminate the quantitation of the molecules in the presence of interference that was observed when using UV detection. Fixed dose combination tablets are convenient for patient therapy and it is likely that in the future more molecules will be formulated into such dosage forms. However formulations such as these can pose significant difficulties when developing and using analytical methods for the quantitation of all compounds in the dosage form at the same time, in particular when the compounds have vastly different physico-chemical properties that impact the quality of a separation and therefore the analysis. Therefore when embarking on the development of FDC product cognisance of the difficulties of developing single methods for the analyses is required and approaches to overcome these difficulties should be considered.
- Full Text:
- Date Issued: 2016
- Authors: Koekemoer, Sonya Mariana
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10962/54679 , vital:26599
- Description: In 2014, approximately 6.8 million people in South Africa were HIV-positive, and the majority of those affected are aged 15 or older. A fixed-dose combination (FDC) antiretroviral (ARV) dosage form containing one non-nucleotide reverse transcriptase inhibitor (efavirenz) and two nucleotide reverse transcriptase inhibitors (emtricitabine and tenofovir) was licensed in South Africa in April 2013. New consolidated guidelines for HIV management and prevention of mother to child transmission (PMTCT) were published by the South African Department of Health in December 2014 and the FDC is now the recommended first-line treatment for HIV-positive patients. According to these guidelines all such people aged 15 and older, and weighing more than 40 kg, with a CD4 count of ≤ 500/ μl will be eligible for antiretroviral therapy (ART) using the FDC. In addition every pregnant and breastfeeding woman is eligible for lifelong ART regardless of CD4 count and EFV can be used as first-line treatment for pregnant women regardless of the length of gestation state of the pregnancy at that time. The use of this simplified regime is likely to promote much needed and improved adherence to therapy. An investigation into the development of a stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method for the simultaneous quantitation of EFV, FTC and TNF was undertaken. Isocratic HPLC analysis was found to be unsuitable due to the highly polar FTC molecule eluting in the void. Therefore a gradient HPLC method was developed and validated. The method was validated according to the International Conference on Harmonisation, now known as International Council for Harmonization (ICH). Correlation coefficients > 0.999 were obtained for each assessment of linearity and FTC, TNF and EFV are linear in the range 0.4-40 μg/ml, 0.6-60 μg/ml and 1.2-120 μg/ml. The equation of the best-fit least squares regression lines for FTC, TNF and EFV were y = 0.0191x+0.0007, y = 0.0163x+0.0116 and y = 0.01x+0.016, respectively. The method is accurate as the y-intercept was < 2% of the detector response for all ARV, and the method is precise in terms of intra- and inter-assay precision as all % RSD < 2%. The stability-indicating nature of the method was demonstrated under acidic, alkaline and oxidative stress in addition to UV exposure and elevated temperatures, and the individual chromatograms were overlaid using Empower® 3 Software to establish whether there was interference with the peaks of interest. The forced degradation studies demonstrated the selectivity of the method for the ARV compounds. The method was applied to assay and in vitro dissolution studies of commercially available tablets. The amount of each active ingredient released from Atripla® was determined and compared to the amount of each drug released from Aspen Efavirenz® and Truvada® (a combination of FTC and TNF). The percent FTC released from Atripla® and Truvada® was similar based on the acceptance criteria for immediate-release BCS class 1 compounds. Statistical analysis was undertaken to compare the dissolution profiles of FTC, TNF and EFV. The percent of these compounds released in these studies indicate that bioequivalence testing would be required to declare these products interchangeable. The validated RP-HPLC and in vitro dissolution test method are suitable for routine quality control testing of solid oral dosage forms containing EFV, FTC and TNF, and as the dissolution method can discriminate between different formulations of the same molecule, these tools can also be used for analysis during formulation development studies. The method is not suitable for the analysis of the ARV plasma due to lack of sensitivity and an inability to quantitate the compounds at the required concentration levels. The use of HPLC with mass spectroscopy for quantitation would enhance the sensitivity of the method and may eliminate the quantitation of the molecules in the presence of interference that was observed when using UV detection. Fixed dose combination tablets are convenient for patient therapy and it is likely that in the future more molecules will be formulated into such dosage forms. However formulations such as these can pose significant difficulties when developing and using analytical methods for the quantitation of all compounds in the dosage form at the same time, in particular when the compounds have vastly different physico-chemical properties that impact the quality of a separation and therefore the analysis. Therefore when embarking on the development of FDC product cognisance of the difficulties of developing single methods for the analyses is required and approaches to overcome these difficulties should be considered.
- Full Text:
- Date Issued: 2016
The Representation of Adult Family Members in Selected Children’s Books by Roald Dahl
- Authors: Kerford, Justine
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2387 , http://hdl.handle.net/10962/d1021254
- Description: This thesis focuses on the representation of the five adult family members (mothers, fathers, grandmothers, grandfathers and aunts) that are present in a specialised corpus of Roald Dahl’s children’s literature. Children’s fiction provides insight into how society views childhood as it reflects the dominant ideologies in society (Larkin-Lieffers 2010).The family is “central to most children’s literature” (Alston 2008: 2) which makes the analysis of the family in children’s fiction important. Society favours particular representations of the family, as well as men and women, and these representations are also reflected in the fiction available to readers. I have used Critical Discourse Analysis and Corpus Linguistics in order to establish how adult family members are represented in Dahl’s fiction. The physical description and the verbs of speech that collocate significantly with the different tagged characters are analysed to establish patterns in representation. Verbs of speech give the reader information that allows them to establish the emotion and attitude of the character and this helps the reader make judgements with regards to the positive or negative perception of the character. The repeated use of particular descriptions and verbs of speech primes the reader to associate particular features with certain characters and the evaluation provided by these features bleeds over onto the characters. There is evidence of a continuum of verbs of speech moving from verbs of speech with low pitch and low volume like ‘said’ to ones with a high pitch and high volume like ‘shrieked’. The tagged characters are discussed according to the continuum to establish any patterns the verb of speech use. Women were found to collocate with verbs of speech like ‘shrieked, ‘screamed’ and ‘wailed’ which suggests that women are more hysterically emotional while men collocate with verbs of speech like ‘shouted’ and ‘yelled’ which were less hysterical and suggest aggression. Aunts were the exception to this pattern as they collocated with more masculine verbs of speech, like ‘shouted’. These patterns help establish whether or not the representations follow the dominant ideologies of women being emotional and home bound and men being aggressive and more active in the public sphere.
- Full Text:
- Date Issued: 2016
- Authors: Kerford, Justine
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2387 , http://hdl.handle.net/10962/d1021254
- Description: This thesis focuses on the representation of the five adult family members (mothers, fathers, grandmothers, grandfathers and aunts) that are present in a specialised corpus of Roald Dahl’s children’s literature. Children’s fiction provides insight into how society views childhood as it reflects the dominant ideologies in society (Larkin-Lieffers 2010).The family is “central to most children’s literature” (Alston 2008: 2) which makes the analysis of the family in children’s fiction important. Society favours particular representations of the family, as well as men and women, and these representations are also reflected in the fiction available to readers. I have used Critical Discourse Analysis and Corpus Linguistics in order to establish how adult family members are represented in Dahl’s fiction. The physical description and the verbs of speech that collocate significantly with the different tagged characters are analysed to establish patterns in representation. Verbs of speech give the reader information that allows them to establish the emotion and attitude of the character and this helps the reader make judgements with regards to the positive or negative perception of the character. The repeated use of particular descriptions and verbs of speech primes the reader to associate particular features with certain characters and the evaluation provided by these features bleeds over onto the characters. There is evidence of a continuum of verbs of speech moving from verbs of speech with low pitch and low volume like ‘said’ to ones with a high pitch and high volume like ‘shrieked’. The tagged characters are discussed according to the continuum to establish any patterns the verb of speech use. Women were found to collocate with verbs of speech like ‘shrieked, ‘screamed’ and ‘wailed’ which suggests that women are more hysterically emotional while men collocate with verbs of speech like ‘shouted’ and ‘yelled’ which were less hysterical and suggest aggression. Aunts were the exception to this pattern as they collocated with more masculine verbs of speech, like ‘shouted’. These patterns help establish whether or not the representations follow the dominant ideologies of women being emotional and home bound and men being aggressive and more active in the public sphere.
- Full Text:
- Date Issued: 2016
The design of botanical conservatory facilities at cathedral peak in the Drakensberg, KwaZulu Natal: a cathedral of conservation
- Authors: Hirst, Charné
- Date: 2016
- Subjects: Conservatories -- South Africa -- KwaZulu-Natal -- Design and plans Architecture -- Environmental aspects , Architecture, Modern -- 20th century
- Language: English
- Type: Thesis , Masters , MArch
- Identifier: http://hdl.handle.net/10948/39098 , vital:35042
- Description: This treatise investigates how eco-tourism can be employed to support the development of natural identity and place-making of a sacred environment through architectural intervention in the midst of an industrialised society. The principle argument of this treatise is that through the symbiosis of nature and the built environment, architecture can provide a counter-narrative to the disconnection between humans and nature. With ecotourism being a contemporary attempt to re-connect humans with our natural routes, to create awareness, a spiritual awakening and a global warming crisis intervention, this treatise will be the architectural product of conservation. The unification of ecology and architecture is critical to a contemporary definition of the natural environment. This treatise proposes the design of botanical conservatory facilities at Cathedral Peak, a tourist and research precinct in the renowned natural and cultural National Heritage Site of the Drakensberg Mountains. It presents an architecture which becomes an extension of the landscape and articulates its natural ecological systems through architectural design, while reinforcing the junction of the natural and built environment. It places the focus on integration between inside/outside spaces, in which the harmonious and symbiotic relationship can be experienced. Although it presents a contemporary architecture, it integrates various vernacular material and tectonic references, becoming a symbol of the nature of the place. The proposal is further described as a ‘cathedral of conservation’ designed as a modulated system for the simulation of particular climatic environments, with attributes drawn from the Gothic cathedral archetype in its attention to verticality and detail to materiality, and from a phenomenological perspective of place and identity as a building asserting the distinctive nature of the place. This cathedral of conservation is an architectural response to the sacredness and spirituality of the mountains, inducing a dialogue between the conservatory and the mighty Cathedral Peak which is one of the most famous natural attributes of the Drakensberg and thus the site’s most valuable vista.
- Full Text:
- Date Issued: 2016
- Authors: Hirst, Charné
- Date: 2016
- Subjects: Conservatories -- South Africa -- KwaZulu-Natal -- Design and plans Architecture -- Environmental aspects , Architecture, Modern -- 20th century
- Language: English
- Type: Thesis , Masters , MArch
- Identifier: http://hdl.handle.net/10948/39098 , vital:35042
- Description: This treatise investigates how eco-tourism can be employed to support the development of natural identity and place-making of a sacred environment through architectural intervention in the midst of an industrialised society. The principle argument of this treatise is that through the symbiosis of nature and the built environment, architecture can provide a counter-narrative to the disconnection between humans and nature. With ecotourism being a contemporary attempt to re-connect humans with our natural routes, to create awareness, a spiritual awakening and a global warming crisis intervention, this treatise will be the architectural product of conservation. The unification of ecology and architecture is critical to a contemporary definition of the natural environment. This treatise proposes the design of botanical conservatory facilities at Cathedral Peak, a tourist and research precinct in the renowned natural and cultural National Heritage Site of the Drakensberg Mountains. It presents an architecture which becomes an extension of the landscape and articulates its natural ecological systems through architectural design, while reinforcing the junction of the natural and built environment. It places the focus on integration between inside/outside spaces, in which the harmonious and symbiotic relationship can be experienced. Although it presents a contemporary architecture, it integrates various vernacular material and tectonic references, becoming a symbol of the nature of the place. The proposal is further described as a ‘cathedral of conservation’ designed as a modulated system for the simulation of particular climatic environments, with attributes drawn from the Gothic cathedral archetype in its attention to verticality and detail to materiality, and from a phenomenological perspective of place and identity as a building asserting the distinctive nature of the place. This cathedral of conservation is an architectural response to the sacredness and spirituality of the mountains, inducing a dialogue between the conservatory and the mighty Cathedral Peak which is one of the most famous natural attributes of the Drakensberg and thus the site’s most valuable vista.
- Full Text:
- Date Issued: 2016
An analysis of the risk exposure of adopting IPV6 in enterprise networks
- Authors: Berko, Istvan Sandor
- Date: 2015
- Subjects: International Workshop on Deploying the Future Infrastructure , Computer networks , Computer networks -- Security measures , Computer network protocols
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4722 , http://hdl.handle.net/10962/d1018918
- Description: The IPv6 increased address pool presents changes in resource impact to the Enterprise that, if not adequately addressed, can change risks that are locally significant in IPv4 to risks that can impact the Enterprise in its entirety. The expected conclusion is that the IPv6 environment will impose significant changes in the Enterprise environment - which may negatively impact organisational security if the IPv6 nuances are not adequately addressed. This thesis reviews the risks related to the operation of enterprise networks with the introduction of IPv6. The global trends are discussed to provide insight and background to the IPv6 research space. Analysing the current state of readiness in enterprise networks, quantifies the value of developing this thesis. The base controls that should be deployed in enterprise networks to prevent the abuse of IPv6 through tunnelling and the protection of the enterprise access layer are discussed. A series of case studies are presented which identify and analyse the impact of certain changes in the IPv6 protocol on the enterprise networks. The case studies also identify mitigation techniques to reduce risk.
- Full Text:
- Date Issued: 2015
- Authors: Berko, Istvan Sandor
- Date: 2015
- Subjects: International Workshop on Deploying the Future Infrastructure , Computer networks , Computer networks -- Security measures , Computer network protocols
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4722 , http://hdl.handle.net/10962/d1018918
- Description: The IPv6 increased address pool presents changes in resource impact to the Enterprise that, if not adequately addressed, can change risks that are locally significant in IPv4 to risks that can impact the Enterprise in its entirety. The expected conclusion is that the IPv6 environment will impose significant changes in the Enterprise environment - which may negatively impact organisational security if the IPv6 nuances are not adequately addressed. This thesis reviews the risks related to the operation of enterprise networks with the introduction of IPv6. The global trends are discussed to provide insight and background to the IPv6 research space. Analysing the current state of readiness in enterprise networks, quantifies the value of developing this thesis. The base controls that should be deployed in enterprise networks to prevent the abuse of IPv6 through tunnelling and the protection of the enterprise access layer are discussed. A series of case studies are presented which identify and analyse the impact of certain changes in the IPv6 protocol on the enterprise networks. The case studies also identify mitigation techniques to reduce risk.
- Full Text:
- Date Issued: 2015
Drought responses of selected C₄ photosynthetic NADP-Me and NAD-Me Panicoideae and Aristidoideae grasses
- Authors: Venter, Nicolaas
- Date: 2015
- Subjects: Aristida , Panicum , Switchgrass , Grasses -- Effect of drought on , Grasses -- Phylogeny , Photosynthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4272 , http://hdl.handle.net/10962/d1018549
- Description: Grass species within South Africa show a photosynthetic subtype and phylogenetic response to rainfall gradients, with Panicoideae species (NADP-Me and NAD-Me) inhabiting mesic environments, while Aristidoideae species (NADP-Me) inhabit more arid environments. It is predicted that climate change will alter rainfall patterns within southern Africa, which could have implications for grassland distributions and functional composition. Globally, and in South Africa, species distributions indicates that NAD-Me species have a preference for more arid environments, but this may be complicated by phylogeny as most NAD-Me species belong to the Chloridoideae subfamily. Additionally, differences in the metabolism and energetic requirements of different carboxylation types are expected to confer different ecological advantages, such as drought tolerance, but the role of these different pathways is not well understood. Based on natural distribution and photosynthetic subtype differences, it was hypothesised that Panicoideae NADP-Me species would be less drought tolerant than Panicoideae NAD-Me and Aristidoideae NADP-Me species and that subtypes and lineages would show different drought recovery rates. Furthermore, drought sensitivity would be of a metabolic and not a stomatal origin and plants that maintained favourable leaf water status would be more drought tolerant and recover faster. This was tested experimentally by comparing Panicoideae species (NADP-Me and NAD-Me) and NADP-Me species (Panicoideae and Aristidoideae). Plants were subjected to a progressive 58 day drought period and a recovery phase where gas exchange, chlorophyll fluorescence and leaf water relations were measured at select intervals. In conjunction with this, a rapid drought experiment was performed on Zea mays (NADP-Me: Panicoideae) plants where similar parameters were measured. Photosynthetic drought and recovery responses showed both a subtype and phylogenetic response. Panicoideae species were less drought tolerant than Aristidoideae species, although Panicoideae NAD-Me showed better recovery rates than Panicoideae NADP-Me species, while Aristidoideae species recovered the quickest. Panicoideae NAD-Me and Aristidoideae species maintained higher leaf water status during drought which contributed to the maintenance of PSII integrity and thus facilitated rapid photosynthetic recovery. During drought Panicoideae species showed greater metabolic limitations over Aristidoideae species and for the first time, lower metabolic limitations were associated with osmotic adjustment. This is a novel finding whereby osmotic adjustment and the subsequent maintenance of leaf water are key to preventing metabolic limitations of photosynthesis in C₄ grasses. Results from the Z. mays rapid drought study showed the limitations to photosynthesis were exclusively metabolic and unlikely to be a direct consequence of turgor loss. It was apparent that the response to drought was stronger amongst lineages, as NADP-Me species from different subfamilies showed a significant difference in drought tolerances. Aristidoideae species’ exceptional drought tolerance and predicted increased aridification could favour these species over Panicoideae species under future climates.
- Full Text:
- Date Issued: 2015
- Authors: Venter, Nicolaas
- Date: 2015
- Subjects: Aristida , Panicum , Switchgrass , Grasses -- Effect of drought on , Grasses -- Phylogeny , Photosynthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4272 , http://hdl.handle.net/10962/d1018549
- Description: Grass species within South Africa show a photosynthetic subtype and phylogenetic response to rainfall gradients, with Panicoideae species (NADP-Me and NAD-Me) inhabiting mesic environments, while Aristidoideae species (NADP-Me) inhabit more arid environments. It is predicted that climate change will alter rainfall patterns within southern Africa, which could have implications for grassland distributions and functional composition. Globally, and in South Africa, species distributions indicates that NAD-Me species have a preference for more arid environments, but this may be complicated by phylogeny as most NAD-Me species belong to the Chloridoideae subfamily. Additionally, differences in the metabolism and energetic requirements of different carboxylation types are expected to confer different ecological advantages, such as drought tolerance, but the role of these different pathways is not well understood. Based on natural distribution and photosynthetic subtype differences, it was hypothesised that Panicoideae NADP-Me species would be less drought tolerant than Panicoideae NAD-Me and Aristidoideae NADP-Me species and that subtypes and lineages would show different drought recovery rates. Furthermore, drought sensitivity would be of a metabolic and not a stomatal origin and plants that maintained favourable leaf water status would be more drought tolerant and recover faster. This was tested experimentally by comparing Panicoideae species (NADP-Me and NAD-Me) and NADP-Me species (Panicoideae and Aristidoideae). Plants were subjected to a progressive 58 day drought period and a recovery phase where gas exchange, chlorophyll fluorescence and leaf water relations were measured at select intervals. In conjunction with this, a rapid drought experiment was performed on Zea mays (NADP-Me: Panicoideae) plants where similar parameters were measured. Photosynthetic drought and recovery responses showed both a subtype and phylogenetic response. Panicoideae species were less drought tolerant than Aristidoideae species, although Panicoideae NAD-Me showed better recovery rates than Panicoideae NADP-Me species, while Aristidoideae species recovered the quickest. Panicoideae NAD-Me and Aristidoideae species maintained higher leaf water status during drought which contributed to the maintenance of PSII integrity and thus facilitated rapid photosynthetic recovery. During drought Panicoideae species showed greater metabolic limitations over Aristidoideae species and for the first time, lower metabolic limitations were associated with osmotic adjustment. This is a novel finding whereby osmotic adjustment and the subsequent maintenance of leaf water are key to preventing metabolic limitations of photosynthesis in C₄ grasses. Results from the Z. mays rapid drought study showed the limitations to photosynthesis were exclusively metabolic and unlikely to be a direct consequence of turgor loss. It was apparent that the response to drought was stronger amongst lineages, as NADP-Me species from different subfamilies showed a significant difference in drought tolerances. Aristidoideae species’ exceptional drought tolerance and predicted increased aridification could favour these species over Panicoideae species under future climates.
- Full Text:
- Date Issued: 2015
Nguni fermented foods: working with indigenous knowledge in the Life Sciences: a case study
- Authors: Hanisi, Nosipho
- Date: 2007
- Subjects: Life sciences -- Study and teaching (Secondary) -- South Africa -- Case studies Environmental education -- South Africa -- Case studies Fermented foods -- Case studies Fermentation Indigenous peoples -- Case studies Nguni (African people) -- Social life and customs. Xhosa (African people) -- Social life and customs. Ethnoscience
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1957 , http://hdl.handle.net/10962/d1008372
- Description: This study examines learning interactions around indigenous ways of knowing associated with fermented grain foods (the making of umqombothi) and the concept of alcoholic fermentation in the Grade 11 Life Sciences curriculum. As an environmental education study it also investigates the cultural significances of the fermented grain food and how learners might make better lifestyle choices. The inclusion of indigenous ways of knowing in the Life Sciences curriculum (FET band) created spaces and opportunities for the use of both knowledge's in sociocultural context and the structured propositions of the learning area in order to construct knowledge. This stimulated learners' understanding of fermentation and also led to a valuing of social context as well as the cultural capital embedded in the indigenous ways of knowing. The study suggests that parental involvement contributed to this valuing of intergenerational ways of knowing. Learners also deliberated how colonial interpretations of Nguni culture and the religious beliefs of Christians had served to marginalise and foster a widening urban rejection of isiXhosa cultural practices related to fermented foods. In their learning and discussion, learners developed new insights and respect for isiXhosa fermentation practices (ukudidiyela) that bring out the food value and nutrition in the grain. The data illustrates that lesson activity that drew on relevant Learning Outcomes and Assessment Standards to integrate Indigenous Knowledge practices in a Life Sciences learning programme, served to enhance learner understanding of alcoholic fermentation. They also document a revaluing of cultural heritage and learners bringing up the problem of alcohol abuse in the community. Curriculum work with Indigenous Knowledge thus not only assisted learners to grasp the science but to use this alongside a valued cultural knowledge capital to deliberate and act on a local concern.
- Full Text:
- Date Issued: 2007
- Authors: Hanisi, Nosipho
- Date: 2007
- Subjects: Life sciences -- Study and teaching (Secondary) -- South Africa -- Case studies Environmental education -- South Africa -- Case studies Fermented foods -- Case studies Fermentation Indigenous peoples -- Case studies Nguni (African people) -- Social life and customs. Xhosa (African people) -- Social life and customs. Ethnoscience
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1957 , http://hdl.handle.net/10962/d1008372
- Description: This study examines learning interactions around indigenous ways of knowing associated with fermented grain foods (the making of umqombothi) and the concept of alcoholic fermentation in the Grade 11 Life Sciences curriculum. As an environmental education study it also investigates the cultural significances of the fermented grain food and how learners might make better lifestyle choices. The inclusion of indigenous ways of knowing in the Life Sciences curriculum (FET band) created spaces and opportunities for the use of both knowledge's in sociocultural context and the structured propositions of the learning area in order to construct knowledge. This stimulated learners' understanding of fermentation and also led to a valuing of social context as well as the cultural capital embedded in the indigenous ways of knowing. The study suggests that parental involvement contributed to this valuing of intergenerational ways of knowing. Learners also deliberated how colonial interpretations of Nguni culture and the religious beliefs of Christians had served to marginalise and foster a widening urban rejection of isiXhosa cultural practices related to fermented foods. In their learning and discussion, learners developed new insights and respect for isiXhosa fermentation practices (ukudidiyela) that bring out the food value and nutrition in the grain. The data illustrates that lesson activity that drew on relevant Learning Outcomes and Assessment Standards to integrate Indigenous Knowledge practices in a Life Sciences learning programme, served to enhance learner understanding of alcoholic fermentation. They also document a revaluing of cultural heritage and learners bringing up the problem of alcohol abuse in the community. Curriculum work with Indigenous Knowledge thus not only assisted learners to grasp the science but to use this alongside a valued cultural knowledge capital to deliberate and act on a local concern.
- Full Text:
- Date Issued: 2007
The role of communication in the management and leadership of a secondary school in Namibia
- Authors: Kaura, Unjee M
- Date: 2005
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1862 , http://hdl.handle.net/10962/d1004559
- Description: Communication is a complex phenomenon, widely regarded as the lifeblood of every organisation, and ironically one of the least researched areas, at least in the field of leadership and management in an educational context. The paucity of literature in this field is evidence of this. This study is an attempt to explore and gain understanding of teachers' experiences and perceptions of the role and functions of communication within an educational organisation, in this case a secondary school in Namibia. The study is an interpretive case study, and employed questionnaires and interviews to gather data from selected participants at the site of research. The findings of the study highlight the dual role of communication as a functioning mechanism as well as a social or binding factor. The role of communication emerges as an essential element in the democratic functioning of the school. It is through communication that democratic practice is achieved as a vehicle for involvement in decision-making, sharing, teamwork, and as a medium for leadership leading to empowerment, human development and organisational development, bringing about change through the sharing of vision. Both formal and informal communication are shown to be functional to the institution. Some of the challenges that have emerged are the dangers of careless and malicious 'badmouthing' in informal communication, the persistence of some degree of top-down communication, and the challenges of communication in multi-cultural settings. The study highlights the need for strategies to improve communication, such as workshops on interpersonal communication.
- Full Text:
- Date Issued: 2005
- Authors: Kaura, Unjee M
- Date: 2005
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1862 , http://hdl.handle.net/10962/d1004559
- Description: Communication is a complex phenomenon, widely regarded as the lifeblood of every organisation, and ironically one of the least researched areas, at least in the field of leadership and management in an educational context. The paucity of literature in this field is evidence of this. This study is an attempt to explore and gain understanding of teachers' experiences and perceptions of the role and functions of communication within an educational organisation, in this case a secondary school in Namibia. The study is an interpretive case study, and employed questionnaires and interviews to gather data from selected participants at the site of research. The findings of the study highlight the dual role of communication as a functioning mechanism as well as a social or binding factor. The role of communication emerges as an essential element in the democratic functioning of the school. It is through communication that democratic practice is achieved as a vehicle for involvement in decision-making, sharing, teamwork, and as a medium for leadership leading to empowerment, human development and organisational development, bringing about change through the sharing of vision. Both formal and informal communication are shown to be functional to the institution. Some of the challenges that have emerged are the dangers of careless and malicious 'badmouthing' in informal communication, the persistence of some degree of top-down communication, and the challenges of communication in multi-cultural settings. The study highlights the need for strategies to improve communication, such as workshops on interpersonal communication.
- Full Text:
- Date Issued: 2005
Research portfolio
- Authors: Kruger, H J M
- Date: 2004
- Subjects: Mathematics -- Study and teaching (Elementary) -- Namibia Problem solving -- Study and teaching (Elementary) -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1874 , http://hdl.handle.net/10962/d1005629
- Description: Paper 1. The purpose of this analysis is to critically evaluate the Lower Primary Mathematics programme within the context of the Namibian educational reform, against the backdrop of learner-centred education from within the Constructivist epistemology. Through the analysis of a small-scale survey, I will try to determine the extent to which learners, teachers and other educationalists, involved in the Lower Primary school phase, understand the new approach to Mathematics and their pedagogical and theoretical insight into the new programme. I will also analyse the syllabus documents in view of the educational policies and further discuss the social, historical and economic background to the reform. I will then analyse the progress or development of the reform process through discussing the learning environment as well as the learners who are the central participants in education. Paper 2.This critical discussion aims to explore the prospects and underlying principles of the epistemologies of two opposing paradigms of education: Behaviourism and Constructivism. I have critically examined and compared the theoretical aspects that shape and inform the model of instruction and the systemic implications of the learning process. The purpose was to compare both learning theories and to draw a conclusion of which the better epistemology is for the teaching and learning process. Paper 3. This is an investigation into the theories that underpin and inform mathematics teaching in the Lower Primary phase of the primary school in Namibia. The Namibian society requires the development of knowledge and understanding, skills and competencies, attitudes and values, which everyone must have to be able to function adequately in society on a social, economic and political level (MBESC 1996). We need to seek ways of enhancing mathematics teaching in Namibia if we want to live up to the expectations of our society. Paper 4. Mathematicians and researchers across the globe have theorised and speculated about education reform movements, which aim for more than just structural knowledge where it concerns Mathematics. This action research study is based on the findings of a pilot study about 'Problem-based Learning', using this as a basis to investigate the relationship between the intentions of the Lower Primary Mathematics curriculum and its implementation at classroom level. This paper reports on a case study of two grade one teachers' perceptions of problem solving as a key component of Mathematics learning and how the implementation of the problem-based approach could be supported through intervention. Data was gathered from a series of cycles of planning, acting, observing and reflecting. Analysis of the data indicates that teachers' professional development lies within a willingness to change and in reflexive practice. Given focused support to teachers could result in the application of contemporary approaches to Mathematics teaching, with an overall improvement of constructivist-oriented learner-centred education.
- Full Text:
- Date Issued: 2004
- Authors: Kruger, H J M
- Date: 2004
- Subjects: Mathematics -- Study and teaching (Elementary) -- Namibia Problem solving -- Study and teaching (Elementary) -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1874 , http://hdl.handle.net/10962/d1005629
- Description: Paper 1. The purpose of this analysis is to critically evaluate the Lower Primary Mathematics programme within the context of the Namibian educational reform, against the backdrop of learner-centred education from within the Constructivist epistemology. Through the analysis of a small-scale survey, I will try to determine the extent to which learners, teachers and other educationalists, involved in the Lower Primary school phase, understand the new approach to Mathematics and their pedagogical and theoretical insight into the new programme. I will also analyse the syllabus documents in view of the educational policies and further discuss the social, historical and economic background to the reform. I will then analyse the progress or development of the reform process through discussing the learning environment as well as the learners who are the central participants in education. Paper 2.This critical discussion aims to explore the prospects and underlying principles of the epistemologies of two opposing paradigms of education: Behaviourism and Constructivism. I have critically examined and compared the theoretical aspects that shape and inform the model of instruction and the systemic implications of the learning process. The purpose was to compare both learning theories and to draw a conclusion of which the better epistemology is for the teaching and learning process. Paper 3. This is an investigation into the theories that underpin and inform mathematics teaching in the Lower Primary phase of the primary school in Namibia. The Namibian society requires the development of knowledge and understanding, skills and competencies, attitudes and values, which everyone must have to be able to function adequately in society on a social, economic and political level (MBESC 1996). We need to seek ways of enhancing mathematics teaching in Namibia if we want to live up to the expectations of our society. Paper 4. Mathematicians and researchers across the globe have theorised and speculated about education reform movements, which aim for more than just structural knowledge where it concerns Mathematics. This action research study is based on the findings of a pilot study about 'Problem-based Learning', using this as a basis to investigate the relationship between the intentions of the Lower Primary Mathematics curriculum and its implementation at classroom level. This paper reports on a case study of two grade one teachers' perceptions of problem solving as a key component of Mathematics learning and how the implementation of the problem-based approach could be supported through intervention. Data was gathered from a series of cycles of planning, acting, observing and reflecting. Analysis of the data indicates that teachers' professional development lies within a willingness to change and in reflexive practice. Given focused support to teachers could result in the application of contemporary approaches to Mathematics teaching, with an overall improvement of constructivist-oriented learner-centred education.
- Full Text:
- Date Issued: 2004
Over-expression, purification and biochemical characterisation of trypanosomal heat shock protein
- Authors: Edkins, Adrienne Lesley
- Date: 2003
- Subjects: Heat shock proteins , Heat shock proteins -- Structure activity relationships
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4106 , http://hdl.handle.net/10962/d1011736 , Heat shock proteins , Heat shock proteins -- Structure activity relationships
- Description: The molecular chaperone process of assisted protein folding, characteristic of members of the Heat Shock Protein 70 kDa (Hsp70) and Heat Shock Protein 40kDa (Hsp40) families, is essential for cytoprotection in stressful cellular conditions. Examples of such conditions are heat shock or invasion by pathogens. The Hsp70/Hsp40 process of assisted protein folding is dependent on ATP (governed by the intrinsic ATPase activity of Hsp70) and the ability of molecular chaperones to recognise and bind non-native protein conformations. Here, we analyse and attempt to characterise the molecular chaperone activity of an inducible, cytoplasmic Hsp70 (TcHsp70) from Trypanosoma cruzi and its interactions with its potential partner Hsp40s, Tcj 1, Tcj2, Tcj3 and Tcj4. A bioinformatic analyses of the primary sequences of the trypanosomal proteins revealed that they all contained the canonical domains that define other members of the Hsp70 and Hsp40 family. Tcj2 and Tcj4 showed deviations from the consensus sequence in their substrate binding regions, which may have implications for their substrate binding specificities. TcHsp70, Tcj 1, Tcj2, Tcj3 and Tcj4 were over-expressed recombinantly as 6xHis-tag fusion proteins in Escherichia coli. His-TcHsp70, Tcjl-His and His-Tcj2 were successfully purified by Nickel-affinity chromatography for functional analyses to assess the molecular chaperone activity of His-TcHsp70 in terms of its ATPase activity and substrate binding ability. The basal ATPase activity of His-TcHsp70 was determined as 40 nmol Pi/min/mg, significantly higher than that reported for other Hsp70s. This basal ATPase activity was stimulated to a maximal level of 60 nmol Pi/min/mg in the presence of His-Tcj2 and a model non-native substrate, reduced carboxymethylated αx-lactalbumin (RCMLA). Using native polyacrylamide gel electrophoresis and Western analysis, His-TcHsp70 was shown to form discrete complexes when in the presence of Tcj 1- His, His-Tcj2 and/or RCMLA. These complexes potentially represent His-TcHsp70 - RCMLA or His-TcHsp70 - Tcj interactions, that may be indicative of chaperone activity. In vivo complementation assays showed that Tcj2, but not Tcj3, was able to overcome the temperature sensitivity of the ydjJ mutant Saccharomyces cerevisiae strain JJ160, suggesting that Tcj2 may be functionally equivalent to the yeast Hsp40 Ydj1.
- Full Text:
- Date Issued: 2003
- Authors: Edkins, Adrienne Lesley
- Date: 2003
- Subjects: Heat shock proteins , Heat shock proteins -- Structure activity relationships
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4106 , http://hdl.handle.net/10962/d1011736 , Heat shock proteins , Heat shock proteins -- Structure activity relationships
- Description: The molecular chaperone process of assisted protein folding, characteristic of members of the Heat Shock Protein 70 kDa (Hsp70) and Heat Shock Protein 40kDa (Hsp40) families, is essential for cytoprotection in stressful cellular conditions. Examples of such conditions are heat shock or invasion by pathogens. The Hsp70/Hsp40 process of assisted protein folding is dependent on ATP (governed by the intrinsic ATPase activity of Hsp70) and the ability of molecular chaperones to recognise and bind non-native protein conformations. Here, we analyse and attempt to characterise the molecular chaperone activity of an inducible, cytoplasmic Hsp70 (TcHsp70) from Trypanosoma cruzi and its interactions with its potential partner Hsp40s, Tcj 1, Tcj2, Tcj3 and Tcj4. A bioinformatic analyses of the primary sequences of the trypanosomal proteins revealed that they all contained the canonical domains that define other members of the Hsp70 and Hsp40 family. Tcj2 and Tcj4 showed deviations from the consensus sequence in their substrate binding regions, which may have implications for their substrate binding specificities. TcHsp70, Tcj 1, Tcj2, Tcj3 and Tcj4 were over-expressed recombinantly as 6xHis-tag fusion proteins in Escherichia coli. His-TcHsp70, Tcjl-His and His-Tcj2 were successfully purified by Nickel-affinity chromatography for functional analyses to assess the molecular chaperone activity of His-TcHsp70 in terms of its ATPase activity and substrate binding ability. The basal ATPase activity of His-TcHsp70 was determined as 40 nmol Pi/min/mg, significantly higher than that reported for other Hsp70s. This basal ATPase activity was stimulated to a maximal level of 60 nmol Pi/min/mg in the presence of His-Tcj2 and a model non-native substrate, reduced carboxymethylated αx-lactalbumin (RCMLA). Using native polyacrylamide gel electrophoresis and Western analysis, His-TcHsp70 was shown to form discrete complexes when in the presence of Tcj 1- His, His-Tcj2 and/or RCMLA. These complexes potentially represent His-TcHsp70 - RCMLA or His-TcHsp70 - Tcj interactions, that may be indicative of chaperone activity. In vivo complementation assays showed that Tcj2, but not Tcj3, was able to overcome the temperature sensitivity of the ydjJ mutant Saccharomyces cerevisiae strain JJ160, suggesting that Tcj2 may be functionally equivalent to the yeast Hsp40 Ydj1.
- Full Text:
- Date Issued: 2003
The natural product chemistry of South African Plocamium species
- Authors: Knott, Michael George
- Date: 2003
- Subjects: Marine algae -- South Africa Red algae -- South Africa Green algae -- South Africa Halimeda -- South Africa
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:3820 , http://hdl.handle.net/10962/d1004920
- Description: The brine shrimp lethality assay was used as a preliminary tool to screen eighteen seaweeds collected from the South African coast. Of the seaweeds tested, the red algae Plocamium corallorhiza and Hypnea rosea, and the green alga Halimeda sp., showed the most potent activity. The chemical investigation of P. corallorhiza resulted in the isolation and structural elucidation of five previously undescribed secondary metabolites, along with three known compounds and four possible artifacts of the extraction process. Standard spectroscopic methods and comparison with known compounds were used to determine the structures of the new metabolites. The new compounds included the linear halogenated monoterpenes 4,8-dibromo-1, 1-dichloro-3,7-dimethyl-2,6-octadiene (99), 4,6-dibromo-l, 1-dichloro-3,7-dimethyl-2,7-octadiene (100), 4,8-dibromo-l, 1,7-trichloro-3,7-dimethyl-2,5-octadiene (101) and 3,4,6,7-tetrachloro-3,7-dimethyl-l-octene (102) and the cyclic monoterpene 5-bromo-5-bromomethyl-I-chlorovinyl-2,4-dichloro-methylcyclohexane (103) while the known compounds were identified as 4-bromo-5-bromomethyl-1chlorovinyl-2,5-dichloro-methylcyclohexane (35), 1,4,8-tribromo-3, 7 -dichloro-3,7-dimethyl-1,5-octadiene (94) and 8-bromo-1,3,4,7-tetrachloro-3,7-dimethyl-1,5-octadiene (96). The four methoxylated compounds (104-107) were presumably formed via a standard substitution reaction between the halogenated monoterpenes 96 and 101 and MeOH, which was used as a component in the extraction solvent. With over 100 000 natural products having been reported, it has become necessary to employ an efficient dereplication strategy to quickly identify known compounds. A simple Gas Chromatography-Mass Spectrometry (GC-MS) method for the efficient physicochemical screening, identification and dereplication of Plocamium metabolites was developed. In this study the crude extracts of P. corallorhiza, P. cornutum and P. maxillosum were screened by GC-MS and the retention times and mass spectral fragmentation patterns of compounds 94, 96, 99 - 107 were used to quickly identify known and new compounds in the crude extracts of P. cornutum and P. maxillosum. This data indicated that compounds 99, 100, 103 were present in both P. corallorhiza and P.cornutum, while compound 102 was found to be present in P. corallorhiza, P. cornutum and P. maxillosum. These studies also indicated that ecotypes and chemotypes are not a significant feature of P. corallorhiza and P. cornutum. Different species of Plocamium (namely: P. corallorhiza, P. cornutum, and P. maxillosum) have very different chemical profiles, and GC may therefore have appreciable taxonomic application in the identification of the different Plocamium spp. which are endemic to South Africa.
- Full Text:
- Date Issued: 2003
- Authors: Knott, Michael George
- Date: 2003
- Subjects: Marine algae -- South Africa Red algae -- South Africa Green algae -- South Africa Halimeda -- South Africa
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:3820 , http://hdl.handle.net/10962/d1004920
- Description: The brine shrimp lethality assay was used as a preliminary tool to screen eighteen seaweeds collected from the South African coast. Of the seaweeds tested, the red algae Plocamium corallorhiza and Hypnea rosea, and the green alga Halimeda sp., showed the most potent activity. The chemical investigation of P. corallorhiza resulted in the isolation and structural elucidation of five previously undescribed secondary metabolites, along with three known compounds and four possible artifacts of the extraction process. Standard spectroscopic methods and comparison with known compounds were used to determine the structures of the new metabolites. The new compounds included the linear halogenated monoterpenes 4,8-dibromo-1, 1-dichloro-3,7-dimethyl-2,6-octadiene (99), 4,6-dibromo-l, 1-dichloro-3,7-dimethyl-2,7-octadiene (100), 4,8-dibromo-l, 1,7-trichloro-3,7-dimethyl-2,5-octadiene (101) and 3,4,6,7-tetrachloro-3,7-dimethyl-l-octene (102) and the cyclic monoterpene 5-bromo-5-bromomethyl-I-chlorovinyl-2,4-dichloro-methylcyclohexane (103) while the known compounds were identified as 4-bromo-5-bromomethyl-1chlorovinyl-2,5-dichloro-methylcyclohexane (35), 1,4,8-tribromo-3, 7 -dichloro-3,7-dimethyl-1,5-octadiene (94) and 8-bromo-1,3,4,7-tetrachloro-3,7-dimethyl-1,5-octadiene (96). The four methoxylated compounds (104-107) were presumably formed via a standard substitution reaction between the halogenated monoterpenes 96 and 101 and MeOH, which was used as a component in the extraction solvent. With over 100 000 natural products having been reported, it has become necessary to employ an efficient dereplication strategy to quickly identify known compounds. A simple Gas Chromatography-Mass Spectrometry (GC-MS) method for the efficient physicochemical screening, identification and dereplication of Plocamium metabolites was developed. In this study the crude extracts of P. corallorhiza, P. cornutum and P. maxillosum were screened by GC-MS and the retention times and mass spectral fragmentation patterns of compounds 94, 96, 99 - 107 were used to quickly identify known and new compounds in the crude extracts of P. cornutum and P. maxillosum. This data indicated that compounds 99, 100, 103 were present in both P. corallorhiza and P.cornutum, while compound 102 was found to be present in P. corallorhiza, P. cornutum and P. maxillosum. These studies also indicated that ecotypes and chemotypes are not a significant feature of P. corallorhiza and P. cornutum. Different species of Plocamium (namely: P. corallorhiza, P. cornutum, and P. maxillosum) have very different chemical profiles, and GC may therefore have appreciable taxonomic application in the identification of the different Plocamium spp. which are endemic to South Africa.
- Full Text:
- Date Issued: 2003
Master of Education portfolio
- Authors: Morrison, Paula
- Date: 2000
- Subjects: Environmental education -- South Africa -- Kwazulu Natal
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1671 , http://hdl.handle.net/10962/d1003554
- Description: This report is the culmination of a six year process during which emerged the need to establish a meeting or indaba place for the collaborative 'People and Parks' partnership of the KwaZulu-Natal Nature Conservation Service (NCS) in Hluhluwe-Umfolozi Park (HUP) and stake-holder communities adjacent to the Park. Comprising two parts which compliment each other, the report has been developed to inform, guide and advise the NCS in the planning and development of an education centre in Hluhluwe-Umfolozi Park. Part I documents the processes of engagement and interaction between the NCS in HUP and neighbouring communities during this period, which led to the need for an education centre, whilst placing and contextualizing the process within historical, socio-political and organisational processes. This is taken further with a description of the research process and an analytical narrative of four key programmes. Part I concludes with a summary of the outcomes of the planning process which shows how through local community input and partiCipation, and through networking with other EE practitioners, a conceptual development plan for the Mambeni Education Centre emerged. The second part of this report (Part 2) is the conceptual development plan which has emerged out of the processes described in Part 1. This plan constitutes practical guidelines for the NCS on how to develop and manage the Mambeni Education Centre. More specifically the plan provides ideas about: what type of centre it should be and where it should be located; who the stake-holders are, their educational neees and ideas for possible programmes; the physical and logistical requirements; managemynt and staffing structures and a detailed business plan. The report intends to draw the reader into understanding the complex social and environmental issues that the collaborative partnership of 'People and Parks' are engaging with, so that the Mambeni Environmental Education Centre can playa [more] meaningful and responsive role in contributing to processes of social transformation. In sharing this environmental education re(search) story which represents a unique approach to centre development, it is hoped that the notion of environmental education centres might be viewed by environmental educators through a different set of lenses. Through having the participants' views represented, I wish the report to reflect the richness of the research process.
- Full Text:
- Date Issued: 2000
- Authors: Morrison, Paula
- Date: 2000
- Subjects: Environmental education -- South Africa -- Kwazulu Natal
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1671 , http://hdl.handle.net/10962/d1003554
- Description: This report is the culmination of a six year process during which emerged the need to establish a meeting or indaba place for the collaborative 'People and Parks' partnership of the KwaZulu-Natal Nature Conservation Service (NCS) in Hluhluwe-Umfolozi Park (HUP) and stake-holder communities adjacent to the Park. Comprising two parts which compliment each other, the report has been developed to inform, guide and advise the NCS in the planning and development of an education centre in Hluhluwe-Umfolozi Park. Part I documents the processes of engagement and interaction between the NCS in HUP and neighbouring communities during this period, which led to the need for an education centre, whilst placing and contextualizing the process within historical, socio-political and organisational processes. This is taken further with a description of the research process and an analytical narrative of four key programmes. Part I concludes with a summary of the outcomes of the planning process which shows how through local community input and partiCipation, and through networking with other EE practitioners, a conceptual development plan for the Mambeni Education Centre emerged. The second part of this report (Part 2) is the conceptual development plan which has emerged out of the processes described in Part 1. This plan constitutes practical guidelines for the NCS on how to develop and manage the Mambeni Education Centre. More specifically the plan provides ideas about: what type of centre it should be and where it should be located; who the stake-holders are, their educational neees and ideas for possible programmes; the physical and logistical requirements; managemynt and staffing structures and a detailed business plan. The report intends to draw the reader into understanding the complex social and environmental issues that the collaborative partnership of 'People and Parks' are engaging with, so that the Mambeni Environmental Education Centre can playa [more] meaningful and responsive role in contributing to processes of social transformation. In sharing this environmental education re(search) story which represents a unique approach to centre development, it is hoped that the notion of environmental education centres might be viewed by environmental educators through a different set of lenses. Through having the participants' views represented, I wish the report to reflect the richness of the research process.
- Full Text:
- Date Issued: 2000
Sarcasm, conflict and style in Mtywaku's plays
- Authors: Bokwe, Goliath Dumezweni
- Date: 1993
- Subjects: Xhosa drama -- History and criticism , Xhosa language -- Terms and phrases , Drama -- Black authors -- History and criticism , Playwriting
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3594 , http://hdl.handle.net/10962/d1002169 , Xhosa drama -- History and criticism , Xhosa language -- Terms and phrases , Drama -- Black authors -- History and criticism , Playwriting
- Description: The following main aspects of Mtywaku's plays have been dealt with in the dissertation: (i) Sarcasm (ii) Conflict (iii) Style.
- Full Text:
- Date Issued: 1993
- Authors: Bokwe, Goliath Dumezweni
- Date: 1993
- Subjects: Xhosa drama -- History and criticism , Xhosa language -- Terms and phrases , Drama -- Black authors -- History and criticism , Playwriting
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3594 , http://hdl.handle.net/10962/d1002169 , Xhosa drama -- History and criticism , Xhosa language -- Terms and phrases , Drama -- Black authors -- History and criticism , Playwriting
- Description: The following main aspects of Mtywaku's plays have been dealt with in the dissertation: (i) Sarcasm (ii) Conflict (iii) Style.
- Full Text:
- Date Issued: 1993