Determinants of foreign direct investments in the motor industry in South Africa
- Authors: Onceya, Siyabulela
- Date: 2011
- Subjects: Investments, Foreign -- South Africa , Automobile industry and trade -- South Africa , Motor industry -- South Africa , Industrial policy -- South Africa
- Language: English
- Type: Thesis , Masters , M Com
- Identifier: vital:11459 , http://hdl.handle.net/10353/545 , Investments, Foreign -- South Africa , Automobile industry and trade -- South Africa , Motor industry -- South Africa , Industrial policy -- South Africa
- Description: The recent surge in foreign capital inflows into developing countries has generated interest among researchers wanting to analyse the major determinants of Foreign Direct Investments in the motor industry (FDIsm). This dissertation investigates the determinants of FDI in the motor industry in South Africa. The underpinning theoretical literature in this study is the Micro-level theory of FDI and the Eclectic theory as well as empirical literature from several authors. The study used quarterly time series data, which covers the period 1994q1- 2008q4. FDIs are modeled as the function of economic growth, interest rates, exchange rate, education and the openness of the country. The variables in the model are tested for stationarity. Cointegration analysis was also used to test for long run relationships between the variables. The trace and the maximum eigenvalue tests suggest that there are at least two cointegration relationships, an error correction modelling technique is used to establish the determinants of foreign direct investment. The error correction model was estimated which provided both long run and short run parameter estimates. The results show that economic growth, education and the openness of the country are positively related to foreign direct investment in the motor industry. Interest rates and exchange rates negatively affect foreign direct investment in the motor industry in South Africa. The results of this study are also supported by the impulse response and variance decomposition tests. The policy recommendation that emanate from this study is that efforts should be made to boost the level of economic growth in order to enhance and attract more foreign investors. It is therefore important for the government to purse policies that will encourage economic growth.
- Full Text:
- Date Issued: 2011
- Authors: Onceya, Siyabulela
- Date: 2011
- Subjects: Investments, Foreign -- South Africa , Automobile industry and trade -- South Africa , Motor industry -- South Africa , Industrial policy -- South Africa
- Language: English
- Type: Thesis , Masters , M Com
- Identifier: vital:11459 , http://hdl.handle.net/10353/545 , Investments, Foreign -- South Africa , Automobile industry and trade -- South Africa , Motor industry -- South Africa , Industrial policy -- South Africa
- Description: The recent surge in foreign capital inflows into developing countries has generated interest among researchers wanting to analyse the major determinants of Foreign Direct Investments in the motor industry (FDIsm). This dissertation investigates the determinants of FDI in the motor industry in South Africa. The underpinning theoretical literature in this study is the Micro-level theory of FDI and the Eclectic theory as well as empirical literature from several authors. The study used quarterly time series data, which covers the period 1994q1- 2008q4. FDIs are modeled as the function of economic growth, interest rates, exchange rate, education and the openness of the country. The variables in the model are tested for stationarity. Cointegration analysis was also used to test for long run relationships between the variables. The trace and the maximum eigenvalue tests suggest that there are at least two cointegration relationships, an error correction modelling technique is used to establish the determinants of foreign direct investment. The error correction model was estimated which provided both long run and short run parameter estimates. The results show that economic growth, education and the openness of the country are positively related to foreign direct investment in the motor industry. Interest rates and exchange rates negatively affect foreign direct investment in the motor industry in South Africa. The results of this study are also supported by the impulse response and variance decomposition tests. The policy recommendation that emanate from this study is that efforts should be made to boost the level of economic growth in order to enhance and attract more foreign investors. It is therefore important for the government to purse policies that will encourage economic growth.
- Full Text:
- Date Issued: 2011
Developing a help-desk system for a multi-purpose ICT platform in a marginalised setting
- Authors: Makombe, Farai
- Date: 2011
- Subjects: Computer industry -- Customer services , Rural development projects -- South Africa -- Eastern Cape , Information technology -- South Africa -- Eastern Cape , Case-based reasoning , Telecommunication -- Technological innovations
- Language: English
- Type: Thesis , Masters , MSc (Computer Science)
- Identifier: vital:11381 , http://hdl.handle.net/10353/315 , Computer industry -- Customer services , Rural development projects -- South Africa -- Eastern Cape , Information technology -- South Africa -- Eastern Cape , Case-based reasoning , Telecommunication -- Technological innovations
- Description: Attempts to bridge the digital divide between urban and rural Information and Communications Technology (ICT) users have led to the deployment of ICT platforms in remote rural areas. This puts an increased demand for skilled support in rural ICT platforms to assist users in resolving technical problems that they face on a daily basis. A web based help desk system is developed and implemented to allow knowledge sharing and collaboration amongst users and experts as a way of ensuring the technical sustainability of the Siyakhula Living Lab, a remote rural based Information and Communications Technology (ICT4D) intervention. The research describes the use of Transactional and Innovation & Creative knowledge management strategies and their associated applications such as case-based reasoning (CBR) methods and collaborative knowledge approaches to develop a help desk support system for a geographically distributed multipurpose ICT centre in Dwesa, a rural remote area in the Eastern Cape Province, South Africa. The system implemented in this study has been validated for functional adequacy and usability within the Siyakhula Living Lab. The results of the evaluation are presented in this thesis to provide the initial validation of the effectiveness of the help desk system. Keywords: ICT4D, ICT, Case-Based Reasoning; Collaborative Knowledge, Technical Sustainability, Help Desk Systems, Siyakhula Living Lab Forums, Issue Tracking, Rural Users, South Africa
- Full Text:
- Date Issued: 2011
- Authors: Makombe, Farai
- Date: 2011
- Subjects: Computer industry -- Customer services , Rural development projects -- South Africa -- Eastern Cape , Information technology -- South Africa -- Eastern Cape , Case-based reasoning , Telecommunication -- Technological innovations
- Language: English
- Type: Thesis , Masters , MSc (Computer Science)
- Identifier: vital:11381 , http://hdl.handle.net/10353/315 , Computer industry -- Customer services , Rural development projects -- South Africa -- Eastern Cape , Information technology -- South Africa -- Eastern Cape , Case-based reasoning , Telecommunication -- Technological innovations
- Description: Attempts to bridge the digital divide between urban and rural Information and Communications Technology (ICT) users have led to the deployment of ICT platforms in remote rural areas. This puts an increased demand for skilled support in rural ICT platforms to assist users in resolving technical problems that they face on a daily basis. A web based help desk system is developed and implemented to allow knowledge sharing and collaboration amongst users and experts as a way of ensuring the technical sustainability of the Siyakhula Living Lab, a remote rural based Information and Communications Technology (ICT4D) intervention. The research describes the use of Transactional and Innovation & Creative knowledge management strategies and their associated applications such as case-based reasoning (CBR) methods and collaborative knowledge approaches to develop a help desk support system for a geographically distributed multipurpose ICT centre in Dwesa, a rural remote area in the Eastern Cape Province, South Africa. The system implemented in this study has been validated for functional adequacy and usability within the Siyakhula Living Lab. The results of the evaluation are presented in this thesis to provide the initial validation of the effectiveness of the help desk system. Keywords: ICT4D, ICT, Case-Based Reasoning; Collaborative Knowledge, Technical Sustainability, Help Desk Systems, Siyakhula Living Lab Forums, Issue Tracking, Rural Users, South Africa
- Full Text:
- Date Issued: 2011
Developing an incubation strategy for Oudtshoorn
- Authors: Petersen, Winifred
- Date: 2011
- Subjects: Business incubators -- South Africa -- Oudshoorn , New business enterprises -- South Africa -- Oudshoorn
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8648 , http://hdl.handle.net/10948/1385 , Business incubators -- South Africa -- Oudshoorn , New business enterprises -- South Africa -- Oudshoorn
- Description: Business incubators, as recognised in their contemporary form, have a history dating back to the 1970s in the United Kingdom and the USA. South Africa is no stranger to this concept of business incubation either: Since the 1980s the Small Business Development Corporation (SBDC) operated business “hives” as clusters of small enterprises. Business incubators are support facilities that empower and stimulate small-entrepreneurial businesses – from the financially vulnerable start-up period, until the time that the fledgling company is ready to operate more autonomously. Business incubators provide, as part of their services, affordable space, financial-management services, sound business advice and other development services. Incubation stimulates the development of small-entrepreneurial businesses and, to this end, helps stimulate the economy. Thus, for South Africa to invest in the development of small growing businesses, is to invest directly in its larger economy and to address its own development challenges like employment-creation, income-generation and the alleviation of poverty. It is in this context that this study discusses the development challenges of one of the rural areas in South Africa, Oudtshoorn, and aims to provide a viable strategy of business incubation for this area, in anticipation that in future lessons can be drawn from this and applied to other rural areas. Oudtshoorn is a town in the Klein Karoo, in the Western Cape Province of South Africa. The strongest sectors in Oudtshoorn’s economy are agriculture and tourism. These two sectors should provide the basis for an empowering business incubator to strengthen and enhance smaller businesses in the town. The study focuses on the development challenges of South Africa and, in particular, a rural town such as Oudtshoorn, the importance of investing in small entrepreneurial businesses so as to strengthen the country’s economy. the nature an significance of a business-incubation strategy for the Oudtshoorn area. Background literature on South Africa’s development challenges was collated as well as information gathered on small-business support and incubation in particular. Literature was retrieved from local institutions as well as national and international sources. Case studies of incubators in South Africa and in other countries were included to enhance the understanding of the importance of business incubation. In addition, the researcher’s close networks with the Oudtshoorn municipality, the local Red Door office and the different role-players in the small-business support sphere allowed for an in-depth assessment of support for such an incubation project and the critical obstacles it may encounter en route.
- Full Text:
- Date Issued: 2011
- Authors: Petersen, Winifred
- Date: 2011
- Subjects: Business incubators -- South Africa -- Oudshoorn , New business enterprises -- South Africa -- Oudshoorn
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8648 , http://hdl.handle.net/10948/1385 , Business incubators -- South Africa -- Oudshoorn , New business enterprises -- South Africa -- Oudshoorn
- Description: Business incubators, as recognised in their contemporary form, have a history dating back to the 1970s in the United Kingdom and the USA. South Africa is no stranger to this concept of business incubation either: Since the 1980s the Small Business Development Corporation (SBDC) operated business “hives” as clusters of small enterprises. Business incubators are support facilities that empower and stimulate small-entrepreneurial businesses – from the financially vulnerable start-up period, until the time that the fledgling company is ready to operate more autonomously. Business incubators provide, as part of their services, affordable space, financial-management services, sound business advice and other development services. Incubation stimulates the development of small-entrepreneurial businesses and, to this end, helps stimulate the economy. Thus, for South Africa to invest in the development of small growing businesses, is to invest directly in its larger economy and to address its own development challenges like employment-creation, income-generation and the alleviation of poverty. It is in this context that this study discusses the development challenges of one of the rural areas in South Africa, Oudtshoorn, and aims to provide a viable strategy of business incubation for this area, in anticipation that in future lessons can be drawn from this and applied to other rural areas. Oudtshoorn is a town in the Klein Karoo, in the Western Cape Province of South Africa. The strongest sectors in Oudtshoorn’s economy are agriculture and tourism. These two sectors should provide the basis for an empowering business incubator to strengthen and enhance smaller businesses in the town. The study focuses on the development challenges of South Africa and, in particular, a rural town such as Oudtshoorn, the importance of investing in small entrepreneurial businesses so as to strengthen the country’s economy. the nature an significance of a business-incubation strategy for the Oudtshoorn area. Background literature on South Africa’s development challenges was collated as well as information gathered on small-business support and incubation in particular. Literature was retrieved from local institutions as well as national and international sources. Case studies of incubators in South Africa and in other countries were included to enhance the understanding of the importance of business incubation. In addition, the researcher’s close networks with the Oudtshoorn municipality, the local Red Door office and the different role-players in the small-business support sphere allowed for an in-depth assessment of support for such an incubation project and the critical obstacles it may encounter en route.
- Full Text:
- Date Issued: 2011
Developing assessment criteria for a sustainable energy sector development project: shale gas exploration in the Karoo
- Authors: Badassey, Jyoti
- Date: 2011
- Subjects: Sustainable development , Economic development -- Sustainability
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9072 , http://hdl.handle.net/10948/d1008405 , Sustainable development , Economic development -- Sustainability
- Description: This research project aims to assess development projects in the energy sector with its focus on the shale gas exploration in the Karoo. The assessment is based on a critical analysis of the concepts and principles of sustainability, complexity and the National Environmental Management Act, using a critical hermeneutics methodology to develop an assessment criterion. Critical hermeneutics is the science and art of interpreting texts, challenging the status quo, its influences and assumptions. Hermeneutics is the reaction to enlightenment fundamentalism, which is an over-reliance on rationality and the scientific method as a primary means of obtaining truth. Hence this research has adopted a triangulation of ideas and concepts derived from sustainability and complexity to find the truth about the sustainability of development projects (Cilliers, 1998; Deleuze & Guattari, 1994; Byrne, 1998). The Central Karoo is situated in the North Eastern part of the Western Province. It is characterised by dry, arid conditions with highly environmentally sensitive land. Central Karoo has the smallest concentration of people in the Western Cape (Van Vuuren, 2008). This research project offers an assessment that will help governments determine the feasibility of energy sector projects since it discusses the impact of exploration for shale gas in the Karoo and explains the process, recommendations and the environmental legislature required for any project to take place in South Africa. Further, it highlights the environmental damage caused by the shale gas exploration as well as the positive economic impact that it could have on the country. For this research, hermeneutics has offered a framework rather than a system; it is a research philosophy that places human experience at the forefront as it honours a variety of interpretations.
- Full Text:
- Date Issued: 2011
- Authors: Badassey, Jyoti
- Date: 2011
- Subjects: Sustainable development , Economic development -- Sustainability
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9072 , http://hdl.handle.net/10948/d1008405 , Sustainable development , Economic development -- Sustainability
- Description: This research project aims to assess development projects in the energy sector with its focus on the shale gas exploration in the Karoo. The assessment is based on a critical analysis of the concepts and principles of sustainability, complexity and the National Environmental Management Act, using a critical hermeneutics methodology to develop an assessment criterion. Critical hermeneutics is the science and art of interpreting texts, challenging the status quo, its influences and assumptions. Hermeneutics is the reaction to enlightenment fundamentalism, which is an over-reliance on rationality and the scientific method as a primary means of obtaining truth. Hence this research has adopted a triangulation of ideas and concepts derived from sustainability and complexity to find the truth about the sustainability of development projects (Cilliers, 1998; Deleuze & Guattari, 1994; Byrne, 1998). The Central Karoo is situated in the North Eastern part of the Western Province. It is characterised by dry, arid conditions with highly environmentally sensitive land. Central Karoo has the smallest concentration of people in the Western Cape (Van Vuuren, 2008). This research project offers an assessment that will help governments determine the feasibility of energy sector projects since it discusses the impact of exploration for shale gas in the Karoo and explains the process, recommendations and the environmental legislature required for any project to take place in South Africa. Further, it highlights the environmental damage caused by the shale gas exploration as well as the positive economic impact that it could have on the country. For this research, hermeneutics has offered a framework rather than a system; it is a research philosophy that places human experience at the forefront as it honours a variety of interpretations.
- Full Text:
- Date Issued: 2011
Developing assessment criteria for successful poverty alleviation with special reference to the Nomzamo Special Care Centre
- Authors: Gidi, Banele Anthony
- Date: 2011
- Subjects: Poverty -- South Africa -- Eastern Cape , Economic development projects -- South Africa -- Eastern Cape , Poverty -- Government policy -- South Africa -- Eastern Cape , Child care services -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9050 , http://hdl.handle.net/10948/1601 , Poverty -- South Africa -- Eastern Cape , Economic development projects -- South Africa -- Eastern Cape , Poverty -- Government policy -- South Africa -- Eastern Cape , Child care services -- South Africa -- Eastern Cape
- Description: While this study is partly theoretical it includes an exploratory case study in which theoretical insights are applied. In the theoretical part of this study, criteria for a successful poverty alleviation project were developed, guided by sustainability theory and complexity theory. It was proposed that researchers could assess existing projects according to these criteria to show where they were successful and where they could improve. The second part of this research consists of a case study, where an actual poverty alleviation project (The Nomzamo Special Care Centre, Peddie, Eastern Cape) was assessed according to the criteria developed in the first part. For this exploratory case study a non-random sample of 9 participants was drawn from the Nomzamo Special Care Centre and other stakeholders in the Ngqushwa Local Municipality in the Eastern Cape. Data was collected using questionnaires, observation and interviews. The results obtained from analysis indicate that project members particularly experience challenges pertaining to financial resources, infrastructure and maintenance. It is recommended that project members receive assistance from the government departments in order for the project to remain sustainable.
- Full Text:
- Date Issued: 2011
- Authors: Gidi, Banele Anthony
- Date: 2011
- Subjects: Poverty -- South Africa -- Eastern Cape , Economic development projects -- South Africa -- Eastern Cape , Poverty -- Government policy -- South Africa -- Eastern Cape , Child care services -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9050 , http://hdl.handle.net/10948/1601 , Poverty -- South Africa -- Eastern Cape , Economic development projects -- South Africa -- Eastern Cape , Poverty -- Government policy -- South Africa -- Eastern Cape , Child care services -- South Africa -- Eastern Cape
- Description: While this study is partly theoretical it includes an exploratory case study in which theoretical insights are applied. In the theoretical part of this study, criteria for a successful poverty alleviation project were developed, guided by sustainability theory and complexity theory. It was proposed that researchers could assess existing projects according to these criteria to show where they were successful and where they could improve. The second part of this research consists of a case study, where an actual poverty alleviation project (The Nomzamo Special Care Centre, Peddie, Eastern Cape) was assessed according to the criteria developed in the first part. For this exploratory case study a non-random sample of 9 participants was drawn from the Nomzamo Special Care Centre and other stakeholders in the Ngqushwa Local Municipality in the Eastern Cape. Data was collected using questionnaires, observation and interviews. The results obtained from analysis indicate that project members particularly experience challenges pertaining to financial resources, infrastructure and maintenance. It is recommended that project members receive assistance from the government departments in order for the project to remain sustainable.
- Full Text:
- Date Issued: 2011
Developing visual images for communicating information aboutantiretroviral side effects to a low-literate population:
- Dowse, Roslind, Ramela, Thato, Barford, Kirsty-Lee, Browne, Sara H
- Authors: Dowse, Roslind , Ramela, Thato , Barford, Kirsty-Lee , Browne, Sara H
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156769 , vital:40048 , https://doi.org/10.2989/16085906.2010.530172
- Description: The side effects of antiretroviral (ARV) therapy are linked to altered quality of life and adherence. Poor adherence has also been associated with low health-literacy skills, with an uninformed patient more likely to make ARV-related decisions that compromise the efficacy of the treatment. Low literacy skills disempower patients in interactions with healthcare providers and preclude the use of existing written patient information materials, which are generally written at a high reading level. Visual images or pictograms used as a counselling tool or included in patient information leaflets have been shown to improve patients’ knowledge, particularly in low-literate groups. The objective of this study was to design visuals or pictograms illustrating various ARV side effects and to evaluate them in a low-literate South African Xhosa population. Core images were generated either from a design workshop or from posed photos or images from textbooks. The research team worked closely with a graphic artist. Initial versions of the images were discussed and assessed in group discussions, and then modified and eventually evaluated quantitatively in individual interviews with 40 participants who each had a maximum of 10 years of schooling.
- Full Text:
- Date Issued: 2011
- Authors: Dowse, Roslind , Ramela, Thato , Barford, Kirsty-Lee , Browne, Sara H
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156769 , vital:40048 , https://doi.org/10.2989/16085906.2010.530172
- Description: The side effects of antiretroviral (ARV) therapy are linked to altered quality of life and adherence. Poor adherence has also been associated with low health-literacy skills, with an uninformed patient more likely to make ARV-related decisions that compromise the efficacy of the treatment. Low literacy skills disempower patients in interactions with healthcare providers and preclude the use of existing written patient information materials, which are generally written at a high reading level. Visual images or pictograms used as a counselling tool or included in patient information leaflets have been shown to improve patients’ knowledge, particularly in low-literate groups. The objective of this study was to design visuals or pictograms illustrating various ARV side effects and to evaluate them in a low-literate South African Xhosa population. Core images were generated either from a design workshop or from posed photos or images from textbooks. The research team worked closely with a graphic artist. Initial versions of the images were discussed and assessed in group discussions, and then modified and eventually evaluated quantitatively in individual interviews with 40 participants who each had a maximum of 10 years of schooling.
- Full Text:
- Date Issued: 2011
Development and testing of liposome encapsulated cyclic dipeptides
- Authors: Kilian, Gareth
- Date: 2011
- Subjects: Peptide antibiotics , Peptide drugs -- Therapeutic use , Peptides -- Synthesis , Antibacterial agents -- Therapeutic use -- Testing , Cyclic peptides , Liposomes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10136 , http://hdl.handle.net/10948/1397 , Peptide antibiotics , Peptide drugs -- Therapeutic use , Peptides -- Synthesis , Antibacterial agents -- Therapeutic use -- Testing , Cyclic peptides , Liposomes
- Description: Cyclic dipeptides have been well characterized for their multitude of biological activities, including antimicrobial and anticancer activities. Cyclo(His-Gly) and cyclo(His-Ala) have also recently been shown to possess significant anticancer activity against a range of cell lines, despite the limitations of these two molecules with respect to their physicochemical properties. Low Log P results in poor cell permeability which can often be problematic for drugs with intracellular mechanisms of action. It can also results in poor biodistribution, and theoretical Log P values for cyclo(His-Gly) and cyclo(His-Ala) were extremely low making them ideal candidates for inclusion into a nanoparticulate drug delivery system. The aim of this study was therefore to formulate and evaluate liposome-encapsulated cyclic dipeptides that increase the tumour-suppressive actions of the cyclic dipeptides, while showing a high degree of specificity for tumour cells. While liposomes are relatively simple to prepare, inter batch variation, low encapsulation and poor stability are often problematic in their production and this has lead to very few liposomal products on the market. This study aimed at using a comprehensive statistical methodology in optimizing liposome formulations encapsulating cyclo(His-Gly) and cyclo(His-Ala). Initial screening of potential factors was conducted using a 25-1 fractional factorial design. This design made use of two levels for each of the five factors and abbreviated the design to minimize runs. Although not much information is provided by these types of designs, the design was sufficient in identifying two critical factors that would be studies further in a more robust design. The two factors selected, based on the screening study, were cholesterol and stearylamine content. These two factors were then used in designing a response surface methodology (RSM) design making use of a central composite rotatable vii design (CCRD) at five levels (-1.5, -1, 0, 1, 1.5) for each factor in order to better understand the design space. Various factors influenced the measured responses of encapsulation efficiency, zeta potential, polydispersity index, cellular uptake and leakage, but most notable were the adverse effects of increasing stearylamine levels on encapsulations efficiency and cholesterol levels on leakage for both cyclo(His-Gly) and cyclo(His-Ala) liposomes. Optimized formulations were derived from the data and prepared. Fair correlation between the predicted and measured responses was obtained. The cytotoxic activity of the encapsulated cyclic dipeptides were assessed against HeLa and MCF-7 cells and found to have limited improvement in activity. However, modification of the polyethylene glycol (PEG) grafted to the liposome surface in order to target folate receptors showed good benefit in significantly decreasing the IC50 values recorded in all cells lines tested, particularly low folate HeLa cells with the lowest IC50 being recorded as 0.0962 mM for folate targeted cyclo(His-Ala). The results therefore indicate that hydrophilic cyclic dipeptides are ideal candidates for inclusion into targeted drug delivery systems such as liposomes. Key words: Liposomes, cyclo(His-Gly), cyclo(His-Ala), cyclic dipeptides, HeLa, MCF-7, folate receptors, factorial design, response surface methodology (RSM), central composite rotatable design (CCRD).
- Full Text:
- Date Issued: 2011
- Authors: Kilian, Gareth
- Date: 2011
- Subjects: Peptide antibiotics , Peptide drugs -- Therapeutic use , Peptides -- Synthesis , Antibacterial agents -- Therapeutic use -- Testing , Cyclic peptides , Liposomes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10136 , http://hdl.handle.net/10948/1397 , Peptide antibiotics , Peptide drugs -- Therapeutic use , Peptides -- Synthesis , Antibacterial agents -- Therapeutic use -- Testing , Cyclic peptides , Liposomes
- Description: Cyclic dipeptides have been well characterized for their multitude of biological activities, including antimicrobial and anticancer activities. Cyclo(His-Gly) and cyclo(His-Ala) have also recently been shown to possess significant anticancer activity against a range of cell lines, despite the limitations of these two molecules with respect to their physicochemical properties. Low Log P results in poor cell permeability which can often be problematic for drugs with intracellular mechanisms of action. It can also results in poor biodistribution, and theoretical Log P values for cyclo(His-Gly) and cyclo(His-Ala) were extremely low making them ideal candidates for inclusion into a nanoparticulate drug delivery system. The aim of this study was therefore to formulate and evaluate liposome-encapsulated cyclic dipeptides that increase the tumour-suppressive actions of the cyclic dipeptides, while showing a high degree of specificity for tumour cells. While liposomes are relatively simple to prepare, inter batch variation, low encapsulation and poor stability are often problematic in their production and this has lead to very few liposomal products on the market. This study aimed at using a comprehensive statistical methodology in optimizing liposome formulations encapsulating cyclo(His-Gly) and cyclo(His-Ala). Initial screening of potential factors was conducted using a 25-1 fractional factorial design. This design made use of two levels for each of the five factors and abbreviated the design to minimize runs. Although not much information is provided by these types of designs, the design was sufficient in identifying two critical factors that would be studies further in a more robust design. The two factors selected, based on the screening study, were cholesterol and stearylamine content. These two factors were then used in designing a response surface methodology (RSM) design making use of a central composite rotatable vii design (CCRD) at five levels (-1.5, -1, 0, 1, 1.5) for each factor in order to better understand the design space. Various factors influenced the measured responses of encapsulation efficiency, zeta potential, polydispersity index, cellular uptake and leakage, but most notable were the adverse effects of increasing stearylamine levels on encapsulations efficiency and cholesterol levels on leakage for both cyclo(His-Gly) and cyclo(His-Ala) liposomes. Optimized formulations were derived from the data and prepared. Fair correlation between the predicted and measured responses was obtained. The cytotoxic activity of the encapsulated cyclic dipeptides were assessed against HeLa and MCF-7 cells and found to have limited improvement in activity. However, modification of the polyethylene glycol (PEG) grafted to the liposome surface in order to target folate receptors showed good benefit in significantly decreasing the IC50 values recorded in all cells lines tested, particularly low folate HeLa cells with the lowest IC50 being recorded as 0.0962 mM for folate targeted cyclo(His-Ala). The results therefore indicate that hydrophilic cyclic dipeptides are ideal candidates for inclusion into targeted drug delivery systems such as liposomes. Key words: Liposomes, cyclo(His-Gly), cyclo(His-Ala), cyclic dipeptides, HeLa, MCF-7, folate receptors, factorial design, response surface methodology (RSM), central composite rotatable design (CCRD).
- Full Text:
- Date Issued: 2011
Development of an ICT road map for eservices in rural areas
- Jere, Norbert R, Thinyane, Mamello, Terzoli, Alfredo
- Authors: Jere, Norbert R , Thinyane, Mamello , Terzoli, Alfredo
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430695 , vital:72709 , https://ieeexplore.ieee.org/abstract/document/6144217
- Description: ICTs, driven by the convergence of computers, telecommunications and traditional media, are crucial for the knowledge-based economy of the future. The rapid technological changes have resulted in different ideas being suggested for the expected ICT applications. As a result, different e-Service applications have being developed as a way to fos-ter ICT developments. However, ICT applications deployed at the mo-ment may not be able to sustain the rural communities in maybe 10 years or more to come. The paper considers the past, analyzes the present and conduct surveys to gain insight into the future. Based on all of this information, the research tries to provide an ICT road map for what is to come. What kind of applications can we develop now to cater for the technological changes, so that the ICT applications developed today would still be compatible with those developed in years to come? The Siyakhula Living Lab (SLL) is used as the case study in this paper and some interviews and literature review are done to get different ide-as on the future of ICTs.
- Full Text:
- Date Issued: 2011
- Authors: Jere, Norbert R , Thinyane, Mamello , Terzoli, Alfredo
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430695 , vital:72709 , https://ieeexplore.ieee.org/abstract/document/6144217
- Description: ICTs, driven by the convergence of computers, telecommunications and traditional media, are crucial for the knowledge-based economy of the future. The rapid technological changes have resulted in different ideas being suggested for the expected ICT applications. As a result, different e-Service applications have being developed as a way to fos-ter ICT developments. However, ICT applications deployed at the mo-ment may not be able to sustain the rural communities in maybe 10 years or more to come. The paper considers the past, analyzes the present and conduct surveys to gain insight into the future. Based on all of this information, the research tries to provide an ICT road map for what is to come. What kind of applications can we develop now to cater for the technological changes, so that the ICT applications developed today would still be compatible with those developed in years to come? The Siyakhula Living Lab (SLL) is used as the case study in this paper and some interviews and literature review are done to get different ide-as on the future of ICTs.
- Full Text:
- Date Issued: 2011
Development of an Interactive Real-Time Negotiation Module for an E-commerce Platform
- Jere, Norbert R, Thinyane, Mamello, Terzoli, Alfredo
- Authors: Jere, Norbert R , Thinyane, Mamello , Terzoli, Alfredo
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430742 , vital:72712 , https://ieeexplore.ieee.org/abstract/document/5954490
- Description: With developments in the Internet and Web-based technologies, dis-tinctions between traditional markets and the global electronic market-place-such as business capital size, are gradually being narrowed down. It is recognized that in the Information Age, e-Commerce is a powerful tool for economic growth of developing countries. While there are indications of e-Commerce patronage among large firms in devel-oping countries, there seems to be little and negligible use of the Inter-net for commerce among small and medium sized firms. However, many of these e-Commerce projects in marginalized areas fail as a re-sult of lack of the required resources to support ICTs. Different ways have been suggested for marketing products online and to create cus-tomer loyalty. This paper discusses a marketing and customer loyalty strategy through a real-time interactive negotiation application, aimed at improving the existing e-Commerce platform. The e-Commerce platform has been deployed as part of the Siyakhula Living Lab ICTD project which is undertaken for the Dwesa community in the Eastern Cape province of South Africa.
- Full Text:
- Date Issued: 2011
- Authors: Jere, Norbert R , Thinyane, Mamello , Terzoli, Alfredo
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430742 , vital:72712 , https://ieeexplore.ieee.org/abstract/document/5954490
- Description: With developments in the Internet and Web-based technologies, dis-tinctions between traditional markets and the global electronic market-place-such as business capital size, are gradually being narrowed down. It is recognized that in the Information Age, e-Commerce is a powerful tool for economic growth of developing countries. While there are indications of e-Commerce patronage among large firms in devel-oping countries, there seems to be little and negligible use of the Inter-net for commerce among small and medium sized firms. However, many of these e-Commerce projects in marginalized areas fail as a re-sult of lack of the required resources to support ICTs. Different ways have been suggested for marketing products online and to create cus-tomer loyalty. This paper discusses a marketing and customer loyalty strategy through a real-time interactive negotiation application, aimed at improving the existing e-Commerce platform. The e-Commerce platform has been deployed as part of the Siyakhula Living Lab ICTD project which is undertaken for the Dwesa community in the Eastern Cape province of South Africa.
- Full Text:
- Date Issued: 2011
Development of an M-Payment system prototype for a marginalized region (Dwesa case study)
- Authors: Mpofu, Handsome C
- Date: 2011
- Subjects: Information technology -- South Africa -- Eastern Cape , Digital divide -- South Africa -- Eastern Cape , Electronic commerce -- South Africa -- Eastern Cape , Mobile communication systems -- South Africa -- Eastern Cape , Home banking services -- South Africa -- Eastern Cape , Rural poor -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Computer Science)
- Identifier: vital:11387 , http://hdl.handle.net/10353/458 , Information technology -- South Africa -- Eastern Cape , Digital divide -- South Africa -- Eastern Cape , Electronic commerce -- South Africa -- Eastern Cape , Mobile communication systems -- South Africa -- Eastern Cape , Home banking services -- South Africa -- Eastern Cape , Rural poor -- South Africa -- Eastern Cape
- Description: Wireless technologies, such as Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Fidelity (WiFi), are making it easier to provide the much needed telecommunications infrastructure in marginalized areas worldwide. These technologies enable the rapid deployment of network services as well as their redistribution throughout these marginalized areas. The ability to bring Internet connectivity to previously underserviced and marginalized areas has the potential to leap-frog socio-economic development and improve participation in the global knowledge economy. This study investigated how wireless access technologies, such as WiMAX and WiFi, can be integrated and used to deliver ubiquitous distributed Internet connectivity with increased capillarity in rural areas. The research was undertaken within an ICT for Development (ICT4D) intervention called Siyakhula Living Lab (SLL) which is based in the Eastern Cape province of South Africa. The research further eliminated the accessibility constraints associated with long distances and remoteness from the Digital Access Nodes (DANs) and provided increased penetration in the network in contrast to the traditional Telecentre model which has been used extensively in ICT4D interventions. This was achieved by deploying WiFi hotspots around the DANs and extending the existing SLL WiMAX backbone to increase the network footprint to neighboring communities. The technical result of the research has been the provision of increased capillarity on the network and service redistribution throughout the entire Dwesa community. Consequently, this has given local community members an opportunity to access network services easily and ubiquitously. Finally, the research investigated and presented the benefits of such wireless network deployment configurations on ICT4D activities in marginalized areas.
- Full Text:
- Date Issued: 2011
- Authors: Mpofu, Handsome C
- Date: 2011
- Subjects: Information technology -- South Africa -- Eastern Cape , Digital divide -- South Africa -- Eastern Cape , Electronic commerce -- South Africa -- Eastern Cape , Mobile communication systems -- South Africa -- Eastern Cape , Home banking services -- South Africa -- Eastern Cape , Rural poor -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Computer Science)
- Identifier: vital:11387 , http://hdl.handle.net/10353/458 , Information technology -- South Africa -- Eastern Cape , Digital divide -- South Africa -- Eastern Cape , Electronic commerce -- South Africa -- Eastern Cape , Mobile communication systems -- South Africa -- Eastern Cape , Home banking services -- South Africa -- Eastern Cape , Rural poor -- South Africa -- Eastern Cape
- Description: Wireless technologies, such as Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Fidelity (WiFi), are making it easier to provide the much needed telecommunications infrastructure in marginalized areas worldwide. These technologies enable the rapid deployment of network services as well as their redistribution throughout these marginalized areas. The ability to bring Internet connectivity to previously underserviced and marginalized areas has the potential to leap-frog socio-economic development and improve participation in the global knowledge economy. This study investigated how wireless access technologies, such as WiMAX and WiFi, can be integrated and used to deliver ubiquitous distributed Internet connectivity with increased capillarity in rural areas. The research was undertaken within an ICT for Development (ICT4D) intervention called Siyakhula Living Lab (SLL) which is based in the Eastern Cape province of South Africa. The research further eliminated the accessibility constraints associated with long distances and remoteness from the Digital Access Nodes (DANs) and provided increased penetration in the network in contrast to the traditional Telecentre model which has been used extensively in ICT4D interventions. This was achieved by deploying WiFi hotspots around the DANs and extending the existing SLL WiMAX backbone to increase the network footprint to neighboring communities. The technical result of the research has been the provision of increased capillarity on the network and service redistribution throughout the entire Dwesa community. Consequently, this has given local community members an opportunity to access network services easily and ubiquitously. Finally, the research investigated and presented the benefits of such wireless network deployment configurations on ICT4D activities in marginalized areas.
- Full Text:
- Date Issued: 2011
Development of isiXhosa text-to-speech modules to support e-Services in marginalized rural areas
- Authors: Mhlana, Siphe
- Date: 2011
- Subjects: Xhosa language -- South Africa -- Eastern Cape , Information technology -- South Africa -- Eastern Cape , Text processing (Computer science) -- South Africa -- Eastern Cape , Literacy -- South Africa -- Eastern Cape , Digital divide -- South Africa -- Eastern Cape , Mobile communication systems -- South Africa -- Eastern Cape , Transmission of texts -- Data processing , Electronic publishing -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Computer Science)
- Identifier: vital:11388 , http://hdl.handle.net/10353/495 , Xhosa language -- South Africa -- Eastern Cape , Information technology -- South Africa -- Eastern Cape , Text processing (Computer science) -- South Africa -- Eastern Cape , Literacy -- South Africa -- Eastern Cape , Digital divide -- South Africa -- Eastern Cape , Mobile communication systems -- South Africa -- Eastern Cape , Transmission of texts -- Data processing , Electronic publishing -- South Africa -- Eastern Cape
- Description: Information and Communication Technology (ICT) projects are being initiated and deployed in marginalized areas to help improve the standard of living for community members. This has lead to a new field, which is responsible for information processing and knowledge development in rural areas, called Information and Communication Technology for Development (ICT4D). An ICT4D projects has been implemented in a marginalized area called Dwesa; this is a rural area situated in the wild coast of the former homelandof Transkei, in the Eastern Cape Province of South Africa. In this rural community there are e-Service projects which have been developed and deployed to support the already existent ICT infrastructure. Some of these projects include the e-Commerce platform, e-Judiciary service, e-Health and e-Government portal. Although these projects are deployed in this area, community members face a language and literacy barrier because these services are typically accessed through English textual interfaces. This becomes a challenge because their language of communication is isiXhosa and some of the community members are illiterate. Most of the rural areas consist of illiterate people who cannot read and write isiXhosa but can only speak the language. This problem of illiteracy in rural areas affects both the youth and the elderly. This research seeks to design, develop and implement software modules that can be used to convert isiXhosa text into natural sounding isiXhosa speech. Such an application is called a Text-to-Speech (TTS) system. The main objective of this research is to improve ICT4D eServices’ usability through the development of an isiXhosa Text-to-Speech system. This research is undertaken within the context of Siyakhula Living Lab (SLL), an ICT4D intervention towards improving the lives of rural communities of South Africa in an attempt to bridge the digital divide. Thedeveloped TTS modules were subsequently tested to determine their applicability to improve eServices usability. The results show acceptable levels of usability as having produced audio utterances for the isiXhosa Text-To-Speech system for marginalized areas.
- Full Text:
- Date Issued: 2011
- Authors: Mhlana, Siphe
- Date: 2011
- Subjects: Xhosa language -- South Africa -- Eastern Cape , Information technology -- South Africa -- Eastern Cape , Text processing (Computer science) -- South Africa -- Eastern Cape , Literacy -- South Africa -- Eastern Cape , Digital divide -- South Africa -- Eastern Cape , Mobile communication systems -- South Africa -- Eastern Cape , Transmission of texts -- Data processing , Electronic publishing -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Computer Science)
- Identifier: vital:11388 , http://hdl.handle.net/10353/495 , Xhosa language -- South Africa -- Eastern Cape , Information technology -- South Africa -- Eastern Cape , Text processing (Computer science) -- South Africa -- Eastern Cape , Literacy -- South Africa -- Eastern Cape , Digital divide -- South Africa -- Eastern Cape , Mobile communication systems -- South Africa -- Eastern Cape , Transmission of texts -- Data processing , Electronic publishing -- South Africa -- Eastern Cape
- Description: Information and Communication Technology (ICT) projects are being initiated and deployed in marginalized areas to help improve the standard of living for community members. This has lead to a new field, which is responsible for information processing and knowledge development in rural areas, called Information and Communication Technology for Development (ICT4D). An ICT4D projects has been implemented in a marginalized area called Dwesa; this is a rural area situated in the wild coast of the former homelandof Transkei, in the Eastern Cape Province of South Africa. In this rural community there are e-Service projects which have been developed and deployed to support the already existent ICT infrastructure. Some of these projects include the e-Commerce platform, e-Judiciary service, e-Health and e-Government portal. Although these projects are deployed in this area, community members face a language and literacy barrier because these services are typically accessed through English textual interfaces. This becomes a challenge because their language of communication is isiXhosa and some of the community members are illiterate. Most of the rural areas consist of illiterate people who cannot read and write isiXhosa but can only speak the language. This problem of illiteracy in rural areas affects both the youth and the elderly. This research seeks to design, develop and implement software modules that can be used to convert isiXhosa text into natural sounding isiXhosa speech. Such an application is called a Text-to-Speech (TTS) system. The main objective of this research is to improve ICT4D eServices’ usability through the development of an isiXhosa Text-to-Speech system. This research is undertaken within the context of Siyakhula Living Lab (SLL), an ICT4D intervention towards improving the lives of rural communities of South Africa in an attempt to bridge the digital divide. Thedeveloped TTS modules were subsequently tested to determine their applicability to improve eServices usability. The results show acceptable levels of usability as having produced audio utterances for the isiXhosa Text-To-Speech system for marginalized areas.
- Full Text:
- Date Issued: 2011
Development of MgZnO-grown MOCVD for UV Photonic applications
- Authors: Talla, Kharouna
- Date: 2011
- Subjects: Photoluminescence , Photonics , Zinc oxide
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10537 , http://hdl.handle.net/10948/d1012585 , Photoluminescence , Photonics , Zinc oxide
- Description: MgxZn1-xO has emerged as a material of great technological importance. Having a direct energy band gap that is tunable throughout much of the ultraviolet (UV) region of the spectrum from the near-UV (~370 nm) to the deep-UV (~176 nm), this compound is of interest for a variety of optoelectronic devices operating in this part of the electromagnetic spectrum. MgxZn1-xO offers advantages over the more mature compound semiconductor AlGaN which stem mainly from the unusually high exciton binding energy (60 meV in ZnO). In this study the growth of ZnO and MgxZn1-xO thin films using metal organic chemical vapour deposition (MOCVD) is systematically investigated. The films are mainly grown on c-Al2O3 and Si (100) and characterized using various techniques, such as photoluminescence (PL), x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and auger electron spectroscopy (AES). The optical and the structural properties are essentially inspected in order to improve their quality. In this thesis the optimisation of ZnO grown using oxygen gas as a new oxidant in our reactor is investigated. The growth temperature and VI/II ratio are varied in order to find optimum parameters giving high quality layers. The effects of Si (100), Si (111), c- and r-sapphire, glass, GaAs and ZnO substrates on the optical, structural and morphological properties of ZnO thin films grown with tert-butanol (TBOH) is examined. Similar morphologies are observed for all substrates, with the films comprising hexagonal columns having cone shaped ends. The photoluminescence spectra are similar, but the various transitions have different relative intensities. It is clear that the different substrates influence neither the orientation of the films, nor the surface morphology, significantly. The photoluminescence hints at larger stacking fault densities in films grown on silicon and glass, however, as evidenced by stronger basal plane stacking fault-related luminescence at ~3.319 eV in the relevant low temperature photoluminescence spectra. The morphology changes with Mg incorporation, from hexagonal columnar structures to cubic faceted columns. From PL, the full with at half maximum is found to gradually increase with Mg content due to alloy broadening. The deep level emission (DLE) is observed to shift with Mg content. By changing the Mg content, the band gap of MgxZn1-xO film is tuned by ~450 meV, which provides an excellent opportunity for band gap engineering for optoelectronic applications. The c-lattice constant of ZnO (5.205 Å) decreases by only 0.6% when the Mg content reaches x=0.39. The introduction of Mg into ZnO is shown to increase the relative PL intensity of stacking fault-related transitions (at 3.314 eV for ZnO). This becomes the dominant near band edge emission. Using TEM a thin Mg rich layer is observed at the interface between the film and the Si or Al2O3. Temperature dependent PL measurements on layers with low Mg concentration (x=0.05 and 0.1) show that the main bound exciton peak exhibits an “s-shaped” temperature dependence, characteristic of localization in a disordered alloy. The origin of the PL line broadening of MgxZn1-xO (x≤0.04) is also analyzed with respect to alloy broadening, taking into account a random cation distribution and alloy clustering. The influence of various MOCVD growth parameters such as growth temperature and VI/II ratio is studied. Varying the temperature from 280 ˚C to 580 ˚C reveals strong morphological changes and optical degradation of the films. Low (<280 ˚C) and high (>580 ˚C) growth temperatures reduce the Mg incorporation. High VI/II ratios also decrease the Mg incorporation, as evidenced by the red-shift of the donor bound exciton (D°X) line. This is ascribed to a stronger premature reaction between (MeCp)2Mg and the oxidant or a preferential heterogeneous interaction between the Mg and oxygen species on the growth front. For both oxidizing agents (O2 and TBOH), the growth at 420 ˚C and a VI-II ratio of 60 on c-Al2O3 gave optimal quality layers in terms of their optical and structural quality. A comparison of films grown using TBOH and O2 gas as oxidizing agent shows no major difference in terms of Mg incorporation. The effect of annealing, the inclusion of a buffer layer and the influence of growth rate on the properties MgxZn1-xO thin films are also reported.
- Full Text:
- Date Issued: 2011
- Authors: Talla, Kharouna
- Date: 2011
- Subjects: Photoluminescence , Photonics , Zinc oxide
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10537 , http://hdl.handle.net/10948/d1012585 , Photoluminescence , Photonics , Zinc oxide
- Description: MgxZn1-xO has emerged as a material of great technological importance. Having a direct energy band gap that is tunable throughout much of the ultraviolet (UV) region of the spectrum from the near-UV (~370 nm) to the deep-UV (~176 nm), this compound is of interest for a variety of optoelectronic devices operating in this part of the electromagnetic spectrum. MgxZn1-xO offers advantages over the more mature compound semiconductor AlGaN which stem mainly from the unusually high exciton binding energy (60 meV in ZnO). In this study the growth of ZnO and MgxZn1-xO thin films using metal organic chemical vapour deposition (MOCVD) is systematically investigated. The films are mainly grown on c-Al2O3 and Si (100) and characterized using various techniques, such as photoluminescence (PL), x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and auger electron spectroscopy (AES). The optical and the structural properties are essentially inspected in order to improve their quality. In this thesis the optimisation of ZnO grown using oxygen gas as a new oxidant in our reactor is investigated. The growth temperature and VI/II ratio are varied in order to find optimum parameters giving high quality layers. The effects of Si (100), Si (111), c- and r-sapphire, glass, GaAs and ZnO substrates on the optical, structural and morphological properties of ZnO thin films grown with tert-butanol (TBOH) is examined. Similar morphologies are observed for all substrates, with the films comprising hexagonal columns having cone shaped ends. The photoluminescence spectra are similar, but the various transitions have different relative intensities. It is clear that the different substrates influence neither the orientation of the films, nor the surface morphology, significantly. The photoluminescence hints at larger stacking fault densities in films grown on silicon and glass, however, as evidenced by stronger basal plane stacking fault-related luminescence at ~3.319 eV in the relevant low temperature photoluminescence spectra. The morphology changes with Mg incorporation, from hexagonal columnar structures to cubic faceted columns. From PL, the full with at half maximum is found to gradually increase with Mg content due to alloy broadening. The deep level emission (DLE) is observed to shift with Mg content. By changing the Mg content, the band gap of MgxZn1-xO film is tuned by ~450 meV, which provides an excellent opportunity for band gap engineering for optoelectronic applications. The c-lattice constant of ZnO (5.205 Å) decreases by only 0.6% when the Mg content reaches x=0.39. The introduction of Mg into ZnO is shown to increase the relative PL intensity of stacking fault-related transitions (at 3.314 eV for ZnO). This becomes the dominant near band edge emission. Using TEM a thin Mg rich layer is observed at the interface between the film and the Si or Al2O3. Temperature dependent PL measurements on layers with low Mg concentration (x=0.05 and 0.1) show that the main bound exciton peak exhibits an “s-shaped” temperature dependence, characteristic of localization in a disordered alloy. The origin of the PL line broadening of MgxZn1-xO (x≤0.04) is also analyzed with respect to alloy broadening, taking into account a random cation distribution and alloy clustering. The influence of various MOCVD growth parameters such as growth temperature and VI/II ratio is studied. Varying the temperature from 280 ˚C to 580 ˚C reveals strong morphological changes and optical degradation of the films. Low (<280 ˚C) and high (>580 ˚C) growth temperatures reduce the Mg incorporation. High VI/II ratios also decrease the Mg incorporation, as evidenced by the red-shift of the donor bound exciton (D°X) line. This is ascribed to a stronger premature reaction between (MeCp)2Mg and the oxidant or a preferential heterogeneous interaction between the Mg and oxygen species on the growth front. For both oxidizing agents (O2 and TBOH), the growth at 420 ˚C and a VI-II ratio of 60 on c-Al2O3 gave optimal quality layers in terms of their optical and structural quality. A comparison of films grown using TBOH and O2 gas as oxidizing agent shows no major difference in terms of Mg incorporation. The effect of annealing, the inclusion of a buffer layer and the influence of growth rate on the properties MgxZn1-xO thin films are also reported.
- Full Text:
- Date Issued: 2011
Development of techniques for the isolation of a granulovirus from potato tuber moth, phthorimaea operculella (Zeller)
- Authors: King, Shirley Anne
- Date: 2011
- Subjects: Potato tuberworm -- Larvae , Agricultural pests -- Biological control , Potato tuberworm , Baculoviruses
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5910 , http://hdl.handle.net/10962/d1015202
- Description: Phthorimaea operculella, commonly known as the Potato Tuber Moth, is an economically important agricultural pest worldwide. The baculovirus, Phthorimaea operculella granulovirus (PhoGV) has been considered as a means of control alternative to chemical control because of its host specificity and harmless impact on other organisms and ecosystems. An isolate of PhoGV obtained from a South African PTM population would be beneficial in the production of a biopesticide, which is not yet available. An efficient and cost-effective rearing method would be advantageous for potential commercial production. Commercial table and seed potato plantations and storage facilities located in Patensie, Bathurst, Howick and Ivanhoe were surveyed for PTM infestations. Patensie was the only site where milky discoloured larvae were found, a potential symptom of PhoGV infection. TEM analysis revealed no virus in these samples. Since no virus was found in the field-collected samples, PTM insects were collected to initiate rearing in the laboratory. PTM was raised by three different methods in the laboratory. A cost/benefit analysis, survival rate, fertility and sex ratio were recorded for each rearing method. Rearing method one was deemed unsuccessful for efficient commercial rearing, as survival percentage and fertility were low. Rearing methods two and three had high survival rates and high fertility, and were efficient and less labour intensive than rearing method one. Rearing method three was the most productive technique, but for commercial production rearing method two was considered the most manageable and efficient. The sex ratio was 1:1 for all three cultures. The cost analysis revealed that rearing methods two and three were less expensive than rearing method one because less labour was required to monitor insects. The success of rearing PTM for 19 months will enable these cultures to be up-scaled to a large production facility for mass rearing. Virus was not found in the field surveys or in laboratory cultures, therefore chemical, temperature, humidity and carbon dioxide stressors were used in an attempt to initiate a baculoviral infection. Symptoms were exhibited in larvae subjected to chemical, temperature and humidity treatments, but these were confirmed by TEM analysis not to be a result of PhoGV infection. The success of rearing PTM in the laboratory suggests that the method could be used in the commercial rearing of the insects in a large mass-rearing facility. The data obtained from induction protocols have allowed for better understanding for future induction for PhoGV and other baculoviruses in other insect species. The failure to isolate a South African PhoGV strain for developing a biopesticide against PTM has motivated further studies in obtaining a baculovirus in order for South Africa to develop a commercial product against this pest.
- Full Text:
- Date Issued: 2011
- Authors: King, Shirley Anne
- Date: 2011
- Subjects: Potato tuberworm -- Larvae , Agricultural pests -- Biological control , Potato tuberworm , Baculoviruses
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5910 , http://hdl.handle.net/10962/d1015202
- Description: Phthorimaea operculella, commonly known as the Potato Tuber Moth, is an economically important agricultural pest worldwide. The baculovirus, Phthorimaea operculella granulovirus (PhoGV) has been considered as a means of control alternative to chemical control because of its host specificity and harmless impact on other organisms and ecosystems. An isolate of PhoGV obtained from a South African PTM population would be beneficial in the production of a biopesticide, which is not yet available. An efficient and cost-effective rearing method would be advantageous for potential commercial production. Commercial table and seed potato plantations and storage facilities located in Patensie, Bathurst, Howick and Ivanhoe were surveyed for PTM infestations. Patensie was the only site where milky discoloured larvae were found, a potential symptom of PhoGV infection. TEM analysis revealed no virus in these samples. Since no virus was found in the field-collected samples, PTM insects were collected to initiate rearing in the laboratory. PTM was raised by three different methods in the laboratory. A cost/benefit analysis, survival rate, fertility and sex ratio were recorded for each rearing method. Rearing method one was deemed unsuccessful for efficient commercial rearing, as survival percentage and fertility were low. Rearing methods two and three had high survival rates and high fertility, and were efficient and less labour intensive than rearing method one. Rearing method three was the most productive technique, but for commercial production rearing method two was considered the most manageable and efficient. The sex ratio was 1:1 for all three cultures. The cost analysis revealed that rearing methods two and three were less expensive than rearing method one because less labour was required to monitor insects. The success of rearing PTM for 19 months will enable these cultures to be up-scaled to a large production facility for mass rearing. Virus was not found in the field surveys or in laboratory cultures, therefore chemical, temperature, humidity and carbon dioxide stressors were used in an attempt to initiate a baculoviral infection. Symptoms were exhibited in larvae subjected to chemical, temperature and humidity treatments, but these were confirmed by TEM analysis not to be a result of PhoGV infection. The success of rearing PTM in the laboratory suggests that the method could be used in the commercial rearing of the insects in a large mass-rearing facility. The data obtained from induction protocols have allowed for better understanding for future induction for PhoGV and other baculoviruses in other insect species. The failure to isolate a South African PhoGV strain for developing a biopesticide against PTM has motivated further studies in obtaining a baculovirus in order for South Africa to develop a commercial product against this pest.
- Full Text:
- Date Issued: 2011
Development, manufacture and assessment of Clobetasol 17-propionate cream formulations
- Fauzee, Ayeshah Fateemah Beebee
- Authors: Fauzee, Ayeshah Fateemah Beebee
- Date: 2011
- Subjects: Adrenocortical hormones , Adrenocortical hormones -- Physiological effect , Adrenocortical hormones -- Testing , Drugs -- Testing , Drugs -- Development , Dermatopharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3856 , http://hdl.handle.net/10962/d1013324
- Description: Eczema or dermatitis is the most common dermatological condition accounting for one-third of all diagnoses in the total population surveyed in South Africa. The prevalence of seborrhoeic dermatitis, extreme photodermatitis and severe psoriasis has increased markedly over the last decade and this increase may be ascribed to the HIV epidemic, first diagnosed in South Africa in 1982. Potent innovator corticosteroids, such as clobetasol 17-propionate (CP) that are used to treat skin disorders, are expensive and there is therefore a need for the production of generic topical corticosteroid products. Formulation and manufacturing processes can be challenging aspects for formulation scientists to produce a robust product that will elicit an appropriate and desirable pharmacokinetic-pharmacodynamic profile. Laboratory scale CP creams were manufactured using different concentrations of Gelot® 64 and propylene glycol in order to establish a composition that would produce a formulation, with similar physical and chemical characteristics and in vitro release profile as an innovator product, Dermovate®. These formulations were assessed in terms of their viscosity, spreadability, pH, content uniformity and in vitro release characteristics using a Franz diffusion cell apparatus. A formulation containing 3% w/w Gelot® 64 and 46% v/v propylene glycol (CPLS-02) was found to exhibit similar viscosity and spreadability characteristics and released CP in a manner similar to Dermovate®. The mechanism of drug release was evaluated using mathematical models such as zero order, first order and Higuchi models. In addition, the in vitro release profiles were characterised by use of difference (f1) and similarity (f2 and Sd) factors. A scale-up formulation with the same % w/w composition as the laboratory scale was also investigated following manufacture using a Wintech® cream/ointment mixer. A Central Composite Design approach was used to investigate the effect of process variables on the performance of the scale-up cream formulations. The homogenisation speed, anchor speed, homogenisation time and cooling time were the process variables investigated. Thirty scale-up batches were manufactured and analysed in terms of their viscosity, spreadability, pH, % drug content and cumulative % drug released per unit area over 72 hours. Model fitting using Design-Expert® software was undertaken and revealed that a correlation between the process variables and the cream responses was most suitably described by quadratic polynomial relationships. The homogenisation speed had the most significant effect on the quality of the scale-up formulations, whereas the anchor speed had a secondary effect on the measured responses, for the formulations investigated. The qualitative interpretation and statistical analysis of the in vitro release data from the scale-up formulations using ANOVA and the f1, f2 and Sd factors revealed that one scale-up batch (CPSU-04), for which the process variables were a homogenisation speed of 1900 rpm, an anchor speed of 35 rpm, a homogenisation time of 100 minutes and a cooling time of 100 minutes, released CP at a similar rate and extent to Dermovate®. A diffusion-controlled mechanism appeared to be predominant in these formulations. A human skin blanching study, using both visual and chromameter assessments, was performed to establish whether batch CPSU-04 was bioequivalent to Dermovate®. The bioequivalence of the selected scale-up formulation to Dermovate® was confirmed, following the calculation of a 90% CI.
- Full Text:
- Date Issued: 2011
- Authors: Fauzee, Ayeshah Fateemah Beebee
- Date: 2011
- Subjects: Adrenocortical hormones , Adrenocortical hormones -- Physiological effect , Adrenocortical hormones -- Testing , Drugs -- Testing , Drugs -- Development , Dermatopharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3856 , http://hdl.handle.net/10962/d1013324
- Description: Eczema or dermatitis is the most common dermatological condition accounting for one-third of all diagnoses in the total population surveyed in South Africa. The prevalence of seborrhoeic dermatitis, extreme photodermatitis and severe psoriasis has increased markedly over the last decade and this increase may be ascribed to the HIV epidemic, first diagnosed in South Africa in 1982. Potent innovator corticosteroids, such as clobetasol 17-propionate (CP) that are used to treat skin disorders, are expensive and there is therefore a need for the production of generic topical corticosteroid products. Formulation and manufacturing processes can be challenging aspects for formulation scientists to produce a robust product that will elicit an appropriate and desirable pharmacokinetic-pharmacodynamic profile. Laboratory scale CP creams were manufactured using different concentrations of Gelot® 64 and propylene glycol in order to establish a composition that would produce a formulation, with similar physical and chemical characteristics and in vitro release profile as an innovator product, Dermovate®. These formulations were assessed in terms of their viscosity, spreadability, pH, content uniformity and in vitro release characteristics using a Franz diffusion cell apparatus. A formulation containing 3% w/w Gelot® 64 and 46% v/v propylene glycol (CPLS-02) was found to exhibit similar viscosity and spreadability characteristics and released CP in a manner similar to Dermovate®. The mechanism of drug release was evaluated using mathematical models such as zero order, first order and Higuchi models. In addition, the in vitro release profiles were characterised by use of difference (f1) and similarity (f2 and Sd) factors. A scale-up formulation with the same % w/w composition as the laboratory scale was also investigated following manufacture using a Wintech® cream/ointment mixer. A Central Composite Design approach was used to investigate the effect of process variables on the performance of the scale-up cream formulations. The homogenisation speed, anchor speed, homogenisation time and cooling time were the process variables investigated. Thirty scale-up batches were manufactured and analysed in terms of their viscosity, spreadability, pH, % drug content and cumulative % drug released per unit area over 72 hours. Model fitting using Design-Expert® software was undertaken and revealed that a correlation between the process variables and the cream responses was most suitably described by quadratic polynomial relationships. The homogenisation speed had the most significant effect on the quality of the scale-up formulations, whereas the anchor speed had a secondary effect on the measured responses, for the formulations investigated. The qualitative interpretation and statistical analysis of the in vitro release data from the scale-up formulations using ANOVA and the f1, f2 and Sd factors revealed that one scale-up batch (CPSU-04), for which the process variables were a homogenisation speed of 1900 rpm, an anchor speed of 35 rpm, a homogenisation time of 100 minutes and a cooling time of 100 minutes, released CP at a similar rate and extent to Dermovate®. A diffusion-controlled mechanism appeared to be predominant in these formulations. A human skin blanching study, using both visual and chromameter assessments, was performed to establish whether batch CPSU-04 was bioequivalent to Dermovate®. The bioequivalence of the selected scale-up formulation to Dermovate® was confirmed, following the calculation of a 90% CI.
- Full Text:
- Date Issued: 2011
Differential expression and regulation of sucrose transporters in rice (Orzya sativa L, cv Nipponbare) during environmental stress conditions
- Authors: Ibraheem, Omodele
- Date: 2011
- Subjects: Crops -- Effect of stress on , Plant molecular genetics , Gene expression , Sucrose , Rice
- Language: English
- Type: Thesis , Doctoral , PhD (Biochemistry)
- Identifier: vital:11249 , http://hdl.handle.net/10353/330 , Crops -- Effect of stress on , Plant molecular genetics , Gene expression , Sucrose , Rice
- Description: Plant productivity is greatly affected by environmental stresses such as drought, salinity and insect herbivory. Plants respond and adapt to these stresses by exhibiting physiological as well as biochemical changes at the cellular and molecular levels in order to survive. Expression of a variety of genes which encode numerous membrane transporters have been demonstrated to be induced by these stresses in a variety of plants. The nutritional status of plants is controlled by these transporters, which are regulated by the transcription of the corresponding genes. In spite of these adverse stress effects on agricultural yield, only a few studies have focused on gene transcriptional and translational regulation of membrane transporters during environmental stress situations. Rice, like other plants, contains a number of sucrose transporters encoded by a family of genes. However, detailed knowledge of their roles, localization and regulation during environmental stress conditions is lacking. Bioinformatic tools were used to identify putative cis-acting regulatory elements that may be involved in the regulation of rice and Arabidopsis thaliana sucrose transporters. The possible cis-acting regulatory elements were predicted by scanning genomic sequences 1.5 kbp upstream of the sucrose transporter genes translational start sites, using Plant CARE, PLACE and Genomatix Matinspector professional data bases. Several cis-acting regulatory elements that are associated with plant development, plant hormonal regulation and stress response were identified, and were present in varying frequencies within the 1.5 kbp of 5′ regulatory region. The putative cis-acting regulatory elements that possibly are involved in the expression and regulation of sucrose transporter gene families in rice and Arabidopsis thaliana during cellular development or environmental stress conditions were identified as: A-box, RY, CAT, Pyrimidine-box, Sucrose-box, ABRE, ARF, ERE, GARE, Me-JA, ARE, DRE, GA-motif, GATA, GT-1, MYC, MYB, W-box, and I-box. Expression analysis was used to elucidate the role of rice (Oryza sativa L. cv Nipponbare) sucrose transporter (OsSUT) genes during drought and salinity treatments of three week old rice plants ( at four leaf stage) over a 10 days. Among the five rice OsSUT genes identified, only OsSUT2 was observed to be progressively up-regulated during drought and salinity treatments, while OsSUT1, OsSUT4 and OsSUT5 were expressed at low levels, and OsSUT3 showed no detectable transcript expression. Sucrose transport will be essential to meet the cellular energy demands and also for osmoprotectant activities during drought and salinity stresses. It therefore indicates that OsSUT2 which facilitates transport of sucrose from photosynthetic cells will be III essential for rice plants to cope with drought and salinity stresses, and cultivars with a higher OsSUT2 expression should be able to tolerate these environmental stresses better. The role of OsSUT in assimilate transport during rusty plum aphids (Hysteroneura setariae; Thomas) infestation on the leaves of three week old rice (Orzya sativa L. cv Nipponbare) cultivar plants, over a time-course of 1 to 10 days of treatments, was also examined by combination of gene expression and β-glucuronidase (GUS) reporter gene analysis. Real Time PCR analysis of the five OsSUT genes revealed that the expression of OsSUT1 was progressively up-regulated during the course of aphid infestation. OsSUT2 and OsSUT4 expression were comparatively low in both the control and treated plants. OsSUT5 showed no clear difference in transcript expression in both control and treated plants, while no detectable transcript expression of OsSUT3 could be found. The up-regulation of OsSUT1 gene was verified at protein level by western blot analysis in both the control and treated plants. OsSUT1 protein expression was found to increase with time during aphid infestation. A similar trend was noticeable in the control plants, however at a lower expression level. These demonstrate that the cellular expression of OsSUT1is regulated by both developmental and environmental factors. OsSUT1-promoter:::GUS reporter gene expression was observed within the vascular parenchyma and/or companion cells associated with phloem sieve elements of the large and small bundles in the phloem tissues of the flag leaf blade regions where feeding aphids were confined, which progressively increased with time of infestation. It is suggested that OsSUT1 may primarily play an essential role in phloem transport of assimilate to wounded tissues from adjacent health tissues or may be involved in the retrieval of assimilate back into the phloem to minimize loss caused by the infestation. Some OsSUT1-promoter:::GUS expression was also found in the metaxylem at 10 days after infestation, which could signify a recovery system in which sucrose lost into the xylem as a result of aphids feeding are retrieved back into the phloem through the vascular parenchyma. This was supported by the exposure of cut ends of matured OsSUT1-promoter:::GUS rice plant leaf to 2% sucrose solution. OsSUT1-promoter:::GUS expression was observed within the protoxylem, xylem and phloem parenchyma tissues. This indicates that sucrose translocating within the xylem tissues are retrieved into the phloem via the OsSUT1 localized within the parenchyma tissues. In conclusion, the differential expression and regulation of rice (Orzya sativa L. cv Nipponbare) sucrose transporters as reported here suggest that OsSUT2 and OsSUT1 were constitutively expressed compared to other rice sucrose transporters during drought and salinity, and rusty plum aphids (Hysteroneura setariae; Thomas) infestation stresses respectively. Thus, the expression and regulation of the sucrose transporters could be related to the physiological and nutritional requirements of the cells during plant developmental or environmental stress state that allows their differential expression.
- Full Text:
- Date Issued: 2011
- Authors: Ibraheem, Omodele
- Date: 2011
- Subjects: Crops -- Effect of stress on , Plant molecular genetics , Gene expression , Sucrose , Rice
- Language: English
- Type: Thesis , Doctoral , PhD (Biochemistry)
- Identifier: vital:11249 , http://hdl.handle.net/10353/330 , Crops -- Effect of stress on , Plant molecular genetics , Gene expression , Sucrose , Rice
- Description: Plant productivity is greatly affected by environmental stresses such as drought, salinity and insect herbivory. Plants respond and adapt to these stresses by exhibiting physiological as well as biochemical changes at the cellular and molecular levels in order to survive. Expression of a variety of genes which encode numerous membrane transporters have been demonstrated to be induced by these stresses in a variety of plants. The nutritional status of plants is controlled by these transporters, which are regulated by the transcription of the corresponding genes. In spite of these adverse stress effects on agricultural yield, only a few studies have focused on gene transcriptional and translational regulation of membrane transporters during environmental stress situations. Rice, like other plants, contains a number of sucrose transporters encoded by a family of genes. However, detailed knowledge of their roles, localization and regulation during environmental stress conditions is lacking. Bioinformatic tools were used to identify putative cis-acting regulatory elements that may be involved in the regulation of rice and Arabidopsis thaliana sucrose transporters. The possible cis-acting regulatory elements were predicted by scanning genomic sequences 1.5 kbp upstream of the sucrose transporter genes translational start sites, using Plant CARE, PLACE and Genomatix Matinspector professional data bases. Several cis-acting regulatory elements that are associated with plant development, plant hormonal regulation and stress response were identified, and were present in varying frequencies within the 1.5 kbp of 5′ regulatory region. The putative cis-acting regulatory elements that possibly are involved in the expression and regulation of sucrose transporter gene families in rice and Arabidopsis thaliana during cellular development or environmental stress conditions were identified as: A-box, RY, CAT, Pyrimidine-box, Sucrose-box, ABRE, ARF, ERE, GARE, Me-JA, ARE, DRE, GA-motif, GATA, GT-1, MYC, MYB, W-box, and I-box. Expression analysis was used to elucidate the role of rice (Oryza sativa L. cv Nipponbare) sucrose transporter (OsSUT) genes during drought and salinity treatments of three week old rice plants ( at four leaf stage) over a 10 days. Among the five rice OsSUT genes identified, only OsSUT2 was observed to be progressively up-regulated during drought and salinity treatments, while OsSUT1, OsSUT4 and OsSUT5 were expressed at low levels, and OsSUT3 showed no detectable transcript expression. Sucrose transport will be essential to meet the cellular energy demands and also for osmoprotectant activities during drought and salinity stresses. It therefore indicates that OsSUT2 which facilitates transport of sucrose from photosynthetic cells will be III essential for rice plants to cope with drought and salinity stresses, and cultivars with a higher OsSUT2 expression should be able to tolerate these environmental stresses better. The role of OsSUT in assimilate transport during rusty plum aphids (Hysteroneura setariae; Thomas) infestation on the leaves of three week old rice (Orzya sativa L. cv Nipponbare) cultivar plants, over a time-course of 1 to 10 days of treatments, was also examined by combination of gene expression and β-glucuronidase (GUS) reporter gene analysis. Real Time PCR analysis of the five OsSUT genes revealed that the expression of OsSUT1 was progressively up-regulated during the course of aphid infestation. OsSUT2 and OsSUT4 expression were comparatively low in both the control and treated plants. OsSUT5 showed no clear difference in transcript expression in both control and treated plants, while no detectable transcript expression of OsSUT3 could be found. The up-regulation of OsSUT1 gene was verified at protein level by western blot analysis in both the control and treated plants. OsSUT1 protein expression was found to increase with time during aphid infestation. A similar trend was noticeable in the control plants, however at a lower expression level. These demonstrate that the cellular expression of OsSUT1is regulated by both developmental and environmental factors. OsSUT1-promoter:::GUS reporter gene expression was observed within the vascular parenchyma and/or companion cells associated with phloem sieve elements of the large and small bundles in the phloem tissues of the flag leaf blade regions where feeding aphids were confined, which progressively increased with time of infestation. It is suggested that OsSUT1 may primarily play an essential role in phloem transport of assimilate to wounded tissues from adjacent health tissues or may be involved in the retrieval of assimilate back into the phloem to minimize loss caused by the infestation. Some OsSUT1-promoter:::GUS expression was also found in the metaxylem at 10 days after infestation, which could signify a recovery system in which sucrose lost into the xylem as a result of aphids feeding are retrieved back into the phloem through the vascular parenchyma. This was supported by the exposure of cut ends of matured OsSUT1-promoter:::GUS rice plant leaf to 2% sucrose solution. OsSUT1-promoter:::GUS expression was observed within the protoxylem, xylem and phloem parenchyma tissues. This indicates that sucrose translocating within the xylem tissues are retrieved into the phloem via the OsSUT1 localized within the parenchyma tissues. In conclusion, the differential expression and regulation of rice (Orzya sativa L. cv Nipponbare) sucrose transporters as reported here suggest that OsSUT2 and OsSUT1 were constitutively expressed compared to other rice sucrose transporters during drought and salinity, and rusty plum aphids (Hysteroneura setariae; Thomas) infestation stresses respectively. Thus, the expression and regulation of the sucrose transporters could be related to the physiological and nutritional requirements of the cells during plant developmental or environmental stress state that allows their differential expression.
- Full Text:
- Date Issued: 2011
Digital forensic model for computer networks
- Authors: Sanyamahwe, Tendai
- Date: 2011
- Subjects: Computer crimes -- Investigation , Evidence, Criminal , Computer networks -- Security measures , Electronic evidence , Forensic sciences , Internet -- Security measures
- Language: English
- Type: Thesis , Masters , MCom (Information Systems)
- Identifier: vital:11127 , http://hdl.handle.net/10353/d1000968 , Computer crimes -- Investigation , Evidence, Criminal , Computer networks -- Security measures , Electronic evidence , Forensic sciences , Internet -- Security measures
- Description: The Internet has become important since information is now stored in digital form and is transported both within and between organisations in large amounts through computer networks. Nevertheless, there are those individuals or groups of people who utilise the Internet to harm other businesses because they can remain relatively anonymous. To prosecute such criminals, forensic practitioners have to follow a well-defined procedure to convict responsible cyber-criminals in a court of law. Log files provide significant digital evidence in computer networks when tracing cyber-criminals. Network log mining is an evolution of typical digital forensics utilising evidence from network devices such as firewalls, switches and routers. Network log mining is a process supported by presiding South African laws such as the Computer Evidence Act, 57 of 1983; the Electronic Communications and Transactions (ECT) Act, 25 of 2002; and the Electronic Communications Act, 36 of 2005. Nevertheless, international laws and regulations supporting network log mining include the Sarbanes-Oxley Act; the Foreign Corrupt Practices Act (FCPA) and the Bribery Act of the USA. A digital forensic model for computer networks focusing on network log mining has been developed based on the literature reviewed and critical thought. The development of the model followed the Design Science methodology. However, this research project argues that there are some important aspects which are not fully addressed by South African presiding legislation supporting digital forensic investigations. With that in mind, this research project proposes some Forensic Investigation Precautions. These precautions were developed as part of the proposed model. The Diffusion of Innovations (DOI) Theory is the framework underpinning the development of the model and how it can be assimilated into the community. The model was sent to IT experts for validation and this provided the qualitative element and the primary data of this research project. From these experts, this study found out that the proposed model is very unique, very comprehensive and has added new knowledge into the field of Information Technology. Also, a paper was written out of this research project.
- Full Text:
- Date Issued: 2011
- Authors: Sanyamahwe, Tendai
- Date: 2011
- Subjects: Computer crimes -- Investigation , Evidence, Criminal , Computer networks -- Security measures , Electronic evidence , Forensic sciences , Internet -- Security measures
- Language: English
- Type: Thesis , Masters , MCom (Information Systems)
- Identifier: vital:11127 , http://hdl.handle.net/10353/d1000968 , Computer crimes -- Investigation , Evidence, Criminal , Computer networks -- Security measures , Electronic evidence , Forensic sciences , Internet -- Security measures
- Description: The Internet has become important since information is now stored in digital form and is transported both within and between organisations in large amounts through computer networks. Nevertheless, there are those individuals or groups of people who utilise the Internet to harm other businesses because they can remain relatively anonymous. To prosecute such criminals, forensic practitioners have to follow a well-defined procedure to convict responsible cyber-criminals in a court of law. Log files provide significant digital evidence in computer networks when tracing cyber-criminals. Network log mining is an evolution of typical digital forensics utilising evidence from network devices such as firewalls, switches and routers. Network log mining is a process supported by presiding South African laws such as the Computer Evidence Act, 57 of 1983; the Electronic Communications and Transactions (ECT) Act, 25 of 2002; and the Electronic Communications Act, 36 of 2005. Nevertheless, international laws and regulations supporting network log mining include the Sarbanes-Oxley Act; the Foreign Corrupt Practices Act (FCPA) and the Bribery Act of the USA. A digital forensic model for computer networks focusing on network log mining has been developed based on the literature reviewed and critical thought. The development of the model followed the Design Science methodology. However, this research project argues that there are some important aspects which are not fully addressed by South African presiding legislation supporting digital forensic investigations. With that in mind, this research project proposes some Forensic Investigation Precautions. These precautions were developed as part of the proposed model. The Diffusion of Innovations (DOI) Theory is the framework underpinning the development of the model and how it can be assimilated into the community. The model was sent to IT experts for validation and this provided the qualitative element and the primary data of this research project. From these experts, this study found out that the proposed model is very unique, very comprehensive and has added new knowledge into the field of Information Technology. Also, a paper was written out of this research project.
- Full Text:
- Date Issued: 2011
Dimethylglyoxime based ion-imprinted polymer for the determination of Ni(II) ions from aqueous samples
- Rammika, M, Darko, G, Tshentu, Z, Sewry, J D, Torto, N
- Authors: Rammika, M , Darko, G , Tshentu, Z , Sewry, J D , Torto, N
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6590 , http://hdl.handle.net/10962/d1004173
- Description: A Ni(II)-dimethylglyoxime ion-imprinted polymer {Ni(II)-DMG IIP} was synthesised by the bulk polymerisation method. The morphology of the Ni(II)-DMG IIP and non-imprinted polymer were observed by scanning electron microscopy and the chemical structures were evaluated by infrared spectroscopy. Selectivity of the Ni(II)-DMG IIP was studied by analysing, using an inductively coupled plasma-optical emission spectrometer, for Ni(II) ions that were spiked with varying concentrations of Co(II), Cu(II), Zn(II), Pd(II), Fe(II), Ca(II), Mg(II), Na(I) and K(I) in aqueous samples. The studies revealed Ni(II) recoveries ranging from 93 to 100% in aqueous solutions with minimal interference from competing ions. Enrichment factors ranged from 2 to 18 with a binding capacity of 120 μg∙g−1. Co(II) was the only ion found to slightly interfere with the determination of Ni(II). Selectivity studies confirmed that the Ni(II)-DMG IIP had very good selectivity, characterised by %RSD of less than 5%. The limits of detection and quantification were 3x10-4 μg∙mℓ−1 and 9x10-4 μg∙mℓ−1, respectively. The accuracy of the method was validated by analysing a custom solution of certified reference material (SEP-3) and the concentration of Ni(II) obtained was in close agreement with the certified one. The Ni(II)-DMG IIP was successfully employed to trap Ni(II) ions from a matrix of sea, river and sewage water. It is believed that the Ni(II)-DMG IIP has potential to be used as sorbent material for pre-concentration of Ni(II) ions from aqueous solutions by solid-phase extraction.
- Full Text:
- Date Issued: 2011
- Authors: Rammika, M , Darko, G , Tshentu, Z , Sewry, J D , Torto, N
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6590 , http://hdl.handle.net/10962/d1004173
- Description: A Ni(II)-dimethylglyoxime ion-imprinted polymer {Ni(II)-DMG IIP} was synthesised by the bulk polymerisation method. The morphology of the Ni(II)-DMG IIP and non-imprinted polymer were observed by scanning electron microscopy and the chemical structures were evaluated by infrared spectroscopy. Selectivity of the Ni(II)-DMG IIP was studied by analysing, using an inductively coupled plasma-optical emission spectrometer, for Ni(II) ions that were spiked with varying concentrations of Co(II), Cu(II), Zn(II), Pd(II), Fe(II), Ca(II), Mg(II), Na(I) and K(I) in aqueous samples. The studies revealed Ni(II) recoveries ranging from 93 to 100% in aqueous solutions with minimal interference from competing ions. Enrichment factors ranged from 2 to 18 with a binding capacity of 120 μg∙g−1. Co(II) was the only ion found to slightly interfere with the determination of Ni(II). Selectivity studies confirmed that the Ni(II)-DMG IIP had very good selectivity, characterised by %RSD of less than 5%. The limits of detection and quantification were 3x10-4 μg∙mℓ−1 and 9x10-4 μg∙mℓ−1, respectively. The accuracy of the method was validated by analysing a custom solution of certified reference material (SEP-3) and the concentration of Ni(II) obtained was in close agreement with the certified one. The Ni(II)-DMG IIP was successfully employed to trap Ni(II) ions from a matrix of sea, river and sewage water. It is believed that the Ni(II)-DMG IIP has potential to be used as sorbent material for pre-concentration of Ni(II) ions from aqueous solutions by solid-phase extraction.
- Full Text:
- Date Issued: 2011
Dismissal law in the education sector
- Authors: Myeki, Mfundo
- Date: 2011
- Subjects: Industrial relations -- South Africa , Labor laws and legislation , Employees -- Dismissal of -- Law and legislation , Labor contract -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10213 , http://hdl.handle.net/10948/1567 , Industrial relations -- South Africa , Labor laws and legislation , Employees -- Dismissal of -- Law and legislation , Labor contract -- South Africa
- Description: This treatise will therefore critically discuss fairness requirements in dismissal law within the context of the education sector from: i) the perspective of a dismissed employee; and ii) the perspective of an employer who wishes to dismiss employees fairly; and iii) the perspective of a deemed dismissal. It will be proper to flow this discussion from the premises of what should be considered procedural and substantive fairness in dismissals.
- Full Text:
- Date Issued: 2011
- Authors: Myeki, Mfundo
- Date: 2011
- Subjects: Industrial relations -- South Africa , Labor laws and legislation , Employees -- Dismissal of -- Law and legislation , Labor contract -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10213 , http://hdl.handle.net/10948/1567 , Industrial relations -- South Africa , Labor laws and legislation , Employees -- Dismissal of -- Law and legislation , Labor contract -- South Africa
- Description: This treatise will therefore critically discuss fairness requirements in dismissal law within the context of the education sector from: i) the perspective of a dismissed employee; and ii) the perspective of an employer who wishes to dismiss employees fairly; and iii) the perspective of a deemed dismissal. It will be proper to flow this discussion from the premises of what should be considered procedural and substantive fairness in dismissals.
- Full Text:
- Date Issued: 2011
Distributing intelligence in the wireless control of a mobile robot using a personal digital assistant
- Authors: Ophoff, Madri
- Date: 2011
- Subjects: Mobile robots , User interfaces (Computer systems)
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9598 , http://hdl.handle.net/10948/1355 , Mobile robots , User interfaces (Computer systems)
- Description: Personal Digital Assistants (PDAs) have recently become a popular component in mobile robots. This compact processing device with its touch screen, variety of built-in features, wireless technologies and affordability can perform various roles within a robotic system. Applications include low-cost prototype development, rapid prototyping, low-cost humanoid robots, robot control, robot vision systems, algorithm development, human-robot interaction, mobile user interfaces as well as wireless robot communication schemes. Limits on processing power, memory, battery life and screen size impact the usefulness of a PDA in some applications. In addition various implementation strategies exist, each with its own strengths and weaknesses. No comparison of the advantages and disadvantages of the different strategies and resulting architectures exist. This makes it difficult for designers to decide on the best use of a PDA within their mobile robot system. This dissertation examines and compares the available mobile robot architectures. A thorough literature study identifies robot projects using a PDA and examines how the designs incorporate a PDA and what purpose it fulfils within the system it forms part of. The dissertation categorises the architectures according to the role of the PDA within the robot system. The hypothesis is made that using a distributed control system architecture makes optimal use of the rich feature set gained from including a PDA in a robot system’s design and simultaneously overcomes the device’s inherent shortcomings. This architecture is developed into a novel distributed intelligence framework that is supported by a hybrid communications architecture, using two wireless connection schemes. A prototype implementation illustrates the framework and communications architecture in action. Various performance measurements are taken in a test scenario for an office robot. The results indicate that the proposed framework does deliver performance gains and is a viable alternative for future projects in this area.
- Full Text:
- Date Issued: 2011
- Authors: Ophoff, Madri
- Date: 2011
- Subjects: Mobile robots , User interfaces (Computer systems)
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9598 , http://hdl.handle.net/10948/1355 , Mobile robots , User interfaces (Computer systems)
- Description: Personal Digital Assistants (PDAs) have recently become a popular component in mobile robots. This compact processing device with its touch screen, variety of built-in features, wireless technologies and affordability can perform various roles within a robotic system. Applications include low-cost prototype development, rapid prototyping, low-cost humanoid robots, robot control, robot vision systems, algorithm development, human-robot interaction, mobile user interfaces as well as wireless robot communication schemes. Limits on processing power, memory, battery life and screen size impact the usefulness of a PDA in some applications. In addition various implementation strategies exist, each with its own strengths and weaknesses. No comparison of the advantages and disadvantages of the different strategies and resulting architectures exist. This makes it difficult for designers to decide on the best use of a PDA within their mobile robot system. This dissertation examines and compares the available mobile robot architectures. A thorough literature study identifies robot projects using a PDA and examines how the designs incorporate a PDA and what purpose it fulfils within the system it forms part of. The dissertation categorises the architectures according to the role of the PDA within the robot system. The hypothesis is made that using a distributed control system architecture makes optimal use of the rich feature set gained from including a PDA in a robot system’s design and simultaneously overcomes the device’s inherent shortcomings. This architecture is developed into a novel distributed intelligence framework that is supported by a hybrid communications architecture, using two wireless connection schemes. A prototype implementation illustrates the framework and communications architecture in action. Various performance measurements are taken in a test scenario for an office robot. The results indicate that the proposed framework does deliver performance gains and is a viable alternative for future projects in this area.
- Full Text:
- Date Issued: 2011
Diverse pollination systems of the twin-spurred orchid genus Satyrium in African grasslands
- Johnson, S.D, Peter, C.I, Ellis, A.G, Boberg, E, Botes, C, Van der Niet, T
- Authors: Johnson, S.D , Peter, C.I , Ellis, A.G , Boberg, E , Botes, C , Van der Niet, T
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6558 , http://hdl.handle.net/10962/d1006025 , http://dx.doi.org/10.1007/s00606-010-0411-1
- Description: The large terrestrial orchid genus Satyrium underwent evolutionary radiations in the Cape floral region and the grasslands of southern and eastern Africa. These radiations were accompanied by tremendous diversification of the unusual twin-spurred flowers that characterize the genus, but pollination data required to interpret these patterns of floral evolution have been lacking for grassland species in the genus. Here we document pollinators, nectar properties, and levels of pollination success for 11 grassland Satyrium species in southern and south-central Africa. Pollinators of these species include bees, beetles, butterflies, hawkmoths, noctuid moths, long-proboscid flies, and sunbirds. Most species appear to be specialized for pollination by one functional pollinator group. Long-proboscid fly pollination systems are reported for the first time in Satyrium (in S. macrophyllum and a high-altitude form of S. neglectum). Floral morphology, especially spur length and rostellum structure, differs markedly among plants with different pollinators, while nectar volume, concentration, and sugar composition are fairly uniform across species. Most taxa exhibited high levels of pollination success (>50% of flowers pollinated), a trend that can be attributed to the presence of nectar in the twin spurs.
- Full Text:
- Date Issued: 2011
- Authors: Johnson, S.D , Peter, C.I , Ellis, A.G , Boberg, E , Botes, C , Van der Niet, T
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6558 , http://hdl.handle.net/10962/d1006025 , http://dx.doi.org/10.1007/s00606-010-0411-1
- Description: The large terrestrial orchid genus Satyrium underwent evolutionary radiations in the Cape floral region and the grasslands of southern and eastern Africa. These radiations were accompanied by tremendous diversification of the unusual twin-spurred flowers that characterize the genus, but pollination data required to interpret these patterns of floral evolution have been lacking for grassland species in the genus. Here we document pollinators, nectar properties, and levels of pollination success for 11 grassland Satyrium species in southern and south-central Africa. Pollinators of these species include bees, beetles, butterflies, hawkmoths, noctuid moths, long-proboscid flies, and sunbirds. Most species appear to be specialized for pollination by one functional pollinator group. Long-proboscid fly pollination systems are reported for the first time in Satyrium (in S. macrophyllum and a high-altitude form of S. neglectum). Floral morphology, especially spur length and rostellum structure, differs markedly among plants with different pollinators, while nectar volume, concentration, and sugar composition are fairly uniform across species. Most taxa exhibited high levels of pollination success (>50% of flowers pollinated), a trend that can be attributed to the presence of nectar in the twin spurs.
- Full Text:
- Date Issued: 2011