An investigation into the use of intuitive control interfaces and distributed processing for enhanced three dimensional sound localization
- Authors: Hedges, M L
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2992 , vital:20350
- Description: This thesis investigates the feasibility of using gestures as a means of control for localizing three dimesional (3D) sound sources in a distributed immersive audio system. A prototype system was implemented and tested which uses state of the art technology to achieve the stated goals. A Windows Kinect is used for gesture recognition which translates human gestures into control messages by the prototype system, which in turn performs actions based on the recognized gestures. The term distributed in the context of this system refers to the audio processing capacity. The prototype system partitions and allocates the processing load between a number of endpoints. The reallocated processing load consists of the mixing of audio samples according to a specification. The endpoints used in this research are XMOS AVB endpoints. The firmware on these endpoints were modified to include the audio mixing capability which was controlled by a state of the art audio distribution networking standard, Ethernet AVB. The hardware used for the implementation of the prototype system is relatively cost efficient in comparison to professional audio hardware, and is also commercially available for end users. The successful implementation and results from user testing of the prototype system demonstrates how it is a feasible option for recording the localization of a sound source. The ability to partition the processing provides a modular approach to building immersive sound systems. This removes the constraint of a centralized mixing console with a predetermined speaker configuration.
- Full Text:
- Date Issued: 2016
- Authors: Hedges, M L
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2992 , vital:20350
- Description: This thesis investigates the feasibility of using gestures as a means of control for localizing three dimesional (3D) sound sources in a distributed immersive audio system. A prototype system was implemented and tested which uses state of the art technology to achieve the stated goals. A Windows Kinect is used for gesture recognition which translates human gestures into control messages by the prototype system, which in turn performs actions based on the recognized gestures. The term distributed in the context of this system refers to the audio processing capacity. The prototype system partitions and allocates the processing load between a number of endpoints. The reallocated processing load consists of the mixing of audio samples according to a specification. The endpoints used in this research are XMOS AVB endpoints. The firmware on these endpoints were modified to include the audio mixing capability which was controlled by a state of the art audio distribution networking standard, Ethernet AVB. The hardware used for the implementation of the prototype system is relatively cost efficient in comparison to professional audio hardware, and is also commercially available for end users. The successful implementation and results from user testing of the prototype system demonstrates how it is a feasible option for recording the localization of a sound source. The ability to partition the processing provides a modular approach to building immersive sound systems. This removes the constraint of a centralized mixing console with a predetermined speaker configuration.
- Full Text:
- Date Issued: 2016
An investigation into the use of intuitive control interfaces and distributed processing for enhanced three dimensional sound localization
- Authors: Hedges, Mitchell Lawrence
- Date: 2016
- Subjects: Human-computer interaction , Acoustic localization , Sound -- Equipment and supplies , Acoustical engineering , Surround-sound systems , Wireless sensor nodes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4724 , http://hdl.handle.net/10962/d1020615
- Description: This thesis investigates the feasibility of using gestures as a means of control for localizing three dimensional (3D) sound sources in a distributed immersive audio system. A prototype system was implemented and tested which uses state of the art technology to achieve the stated goals. A Windows Kinect is used for gesture recognition which translates human gestures into control messages by the prototype system, which in turn performs actions based on the recognized gestures. The term distributed in the context of this system refers to the audio processing capacity. The prototype system partitions and allocates the processing load between a number of endpoints. The reallocated processing load consists of the mixing of audio samples according to a specification. The endpoints used in this research are XMOS AVB endpoints. The firmware on these endpoints were modified to include the audio mixing capability which was controlled by a state of the art audio distribution networking standard, Ethernet AVB. The hardware used for the implementation of the prototype system is relatively cost efficient in comparison to professional audio hardware, and is also commercially available for end users. the successful implementation and results from user testing of the prototype system demonstrates how it is a feasible option for recording the localization of a sound source. The ability to partition the processing provides a modular approach to building immersive sound systems. This removes the constraint of a centralized mixing console with a predetermined speaker configuration.
- Full Text:
- Date Issued: 2016
- Authors: Hedges, Mitchell Lawrence
- Date: 2016
- Subjects: Human-computer interaction , Acoustic localization , Sound -- Equipment and supplies , Acoustical engineering , Surround-sound systems , Wireless sensor nodes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4724 , http://hdl.handle.net/10962/d1020615
- Description: This thesis investigates the feasibility of using gestures as a means of control for localizing three dimensional (3D) sound sources in a distributed immersive audio system. A prototype system was implemented and tested which uses state of the art technology to achieve the stated goals. A Windows Kinect is used for gesture recognition which translates human gestures into control messages by the prototype system, which in turn performs actions based on the recognized gestures. The term distributed in the context of this system refers to the audio processing capacity. The prototype system partitions and allocates the processing load between a number of endpoints. The reallocated processing load consists of the mixing of audio samples according to a specification. The endpoints used in this research are XMOS AVB endpoints. The firmware on these endpoints were modified to include the audio mixing capability which was controlled by a state of the art audio distribution networking standard, Ethernet AVB. The hardware used for the implementation of the prototype system is relatively cost efficient in comparison to professional audio hardware, and is also commercially available for end users. the successful implementation and results from user testing of the prototype system demonstrates how it is a feasible option for recording the localization of a sound source. The ability to partition the processing provides a modular approach to building immersive sound systems. This removes the constraint of a centralized mixing console with a predetermined speaker configuration.
- Full Text:
- Date Issued: 2016
An investigation of absenteeism amongst blue-collar workers: a mixed methods approach
- Authors: Kroon, Kim
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:866 , http://hdl.handle.net/10962/d1021248
- Description: Absenteeism affects organisations in many different ways, therefore it is essential to investigate absenteeism with the aim of minimising absence levels. The focus of the research was to investigate absenteeism amongst blue-collar workers at a Global Logistics Supplier. The objectives of this research were to identify the main types of absenteeism, to compare the views of blue-collar workers and management on the causes attributed to absenteeism, to describe how absenteeism has been measured and managed, and to make recommendations to the company on ways to minimize absenteeism based on the findings. Quantitative data in the form of monthly absenteeism statistics relating to each leave type, was examined for trends relating to absenteeism levels amongst blue-collar workers at the company. Semi-structured interviews were then carried out with management and blue-collar workers to examine the causes of absenteeism and its management. The results showed that there was a discrepancy between the views of management and blue-collar workers at the company on the perceived causes of absenteeism. On the other hand, both management and the blue-collar workers identified Monday and Friday as the most prevalent days on which employees are absent from the workplace. This finding suggests that more research should be conducted on this trend in blue-collar workers. In exploring how absenteeism is dealt with, management within the company stated that discipline was the most effective way of keeping absenteeism levels low amongst employees. The limitations and delimitations of the research were recognised and further research ideas were given. It was also recommended that managers and supervisors address the workplace issues and identify when a worker’s performance and interpersonal relationships are strained in order to effectively minimise absenteeism. It is also recommended they implement a wellness programme.
- Full Text:
- Date Issued: 2016
- Authors: Kroon, Kim
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:866 , http://hdl.handle.net/10962/d1021248
- Description: Absenteeism affects organisations in many different ways, therefore it is essential to investigate absenteeism with the aim of minimising absence levels. The focus of the research was to investigate absenteeism amongst blue-collar workers at a Global Logistics Supplier. The objectives of this research were to identify the main types of absenteeism, to compare the views of blue-collar workers and management on the causes attributed to absenteeism, to describe how absenteeism has been measured and managed, and to make recommendations to the company on ways to minimize absenteeism based on the findings. Quantitative data in the form of monthly absenteeism statistics relating to each leave type, was examined for trends relating to absenteeism levels amongst blue-collar workers at the company. Semi-structured interviews were then carried out with management and blue-collar workers to examine the causes of absenteeism and its management. The results showed that there was a discrepancy between the views of management and blue-collar workers at the company on the perceived causes of absenteeism. On the other hand, both management and the blue-collar workers identified Monday and Friday as the most prevalent days on which employees are absent from the workplace. This finding suggests that more research should be conducted on this trend in blue-collar workers. In exploring how absenteeism is dealt with, management within the company stated that discipline was the most effective way of keeping absenteeism levels low amongst employees. The limitations and delimitations of the research were recognised and further research ideas were given. It was also recommended that managers and supervisors address the workplace issues and identify when a worker’s performance and interpersonal relationships are strained in order to effectively minimise absenteeism. It is also recommended they implement a wellness programme.
- Full Text:
- Date Issued: 2016
An investigation of green marketing opportunities at BOS Ice Tea
- Authors: Ciesielski, Adrian Adam
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:864 , http://hdl.handle.net/10962/d1021246
- Description: The research addresses the marketing activities of BOS Ice Tea, a South African company, and whether they are reflective and grounded within their marketing activities. By analysing public data and interviewing the founding partners, Richard Bowsher and Grant Rushmere, the findings where compared against the marketing paradigms of Ottoman (1999) and the green marketing practices of Gittell et al. (2012). It was determined that the company engages in green activities, but does not communicate them clearly. Further, where the company did promote organic rooibos and sustainability, their actions were not reflective of these behaviours from an academic point of view. Thus, there was the potential for green washing. The research concludes with suggestions for a 4P’s green marketing framework, and comments on areas that need clarity.
- Full Text:
- Date Issued: 2016
- Authors: Ciesielski, Adrian Adam
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:864 , http://hdl.handle.net/10962/d1021246
- Description: The research addresses the marketing activities of BOS Ice Tea, a South African company, and whether they are reflective and grounded within their marketing activities. By analysing public data and interviewing the founding partners, Richard Bowsher and Grant Rushmere, the findings where compared against the marketing paradigms of Ottoman (1999) and the green marketing practices of Gittell et al. (2012). It was determined that the company engages in green activities, but does not communicate them clearly. Further, where the company did promote organic rooibos and sustainability, their actions were not reflective of these behaviours from an academic point of view. Thus, there was the potential for green washing. The research concludes with suggestions for a 4P’s green marketing framework, and comments on areas that need clarity.
- Full Text:
- Date Issued: 2016
An investigation of participative management in a museum in the Eastern Cape, South Africa
- Authors: Madinda, Nozipho
- Date: 2016
- Subjects: Museums -- South Africa -- Eastern Cape -- Management , Management -- Employee participation , Albany Museum (Grahamstown, South Africa)
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2068 , http://hdl.handle.net/10962/d1020847
- Description: The purpose of my research was to investigate participative management at the Albany Museum with a view to generating knowledge and insights that can be used to support senior management’s engagement with participative management at mid-management level. My interest was to investigate participative management with regards to five HODs of the Albany Museum with a view to generating knowledge and insights that can be used to support senior management’s engagement with participative management at mid-management level. The research was informed by the interpretive paradigm. The interpretive paradigm does not concern itself with the search for broadly applicable laws and rules but rather seeks to produce descriptive analyses that emphasise deep interpretation and understanding of social phenomena through the meaning that the people assign to them. This study is mostly descriptive and presents the reality of participants from their own experience. Semi-structured interviews and observation capture ‘insider’ knowledge that is part of an interpretive methodology. The study found that participative management was both understood and generally accepted as a good way to manage an organisation, and even members who were critical of it could see its benefits. However, the fractured and diversified structure of the organisation calls for a particularly skillful application of this management approach, one which would also demand leadership and a greater sense of working towards what are called collegial models of management. Whether this is in fact desirable for a museum is debatable.
- Full Text:
- Date Issued: 2016
- Authors: Madinda, Nozipho
- Date: 2016
- Subjects: Museums -- South Africa -- Eastern Cape -- Management , Management -- Employee participation , Albany Museum (Grahamstown, South Africa)
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2068 , http://hdl.handle.net/10962/d1020847
- Description: The purpose of my research was to investigate participative management at the Albany Museum with a view to generating knowledge and insights that can be used to support senior management’s engagement with participative management at mid-management level. My interest was to investigate participative management with regards to five HODs of the Albany Museum with a view to generating knowledge and insights that can be used to support senior management’s engagement with participative management at mid-management level. The research was informed by the interpretive paradigm. The interpretive paradigm does not concern itself with the search for broadly applicable laws and rules but rather seeks to produce descriptive analyses that emphasise deep interpretation and understanding of social phenomena through the meaning that the people assign to them. This study is mostly descriptive and presents the reality of participants from their own experience. Semi-structured interviews and observation capture ‘insider’ knowledge that is part of an interpretive methodology. The study found that participative management was both understood and generally accepted as a good way to manage an organisation, and even members who were critical of it could see its benefits. However, the fractured and diversified structure of the organisation calls for a particularly skillful application of this management approach, one which would also demand leadership and a greater sense of working towards what are called collegial models of management. Whether this is in fact desirable for a museum is debatable.
- Full Text:
- Date Issued: 2016
An investigation of servant leadership within Rhodes University sports clubs
- Authors: Stiebel, Jessica Lee
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:872 , http://hdl.handle.net/10962/d1021317
- Description: This research investigates the level of servant leadership within Rhodes University sport clubs. The goals of this research are to assess the perception the club members have of their chairperson and to key identify areas of development. The sport clubs at Rhodes University are partially run by chairpersons who are voted into the position by his or her peers of a sports club. The chairpersons work alongside Rhodes University employees who are a part of the Sports Administration team to oversee the running, scheduling and finances of the club. The sports clubs are representative of Rhodes University and it is the chairperson’s responsibility to ensure the club is lead and run effectively. Robert Greenleaf coined the term servant leader in the 1970s (Greenleaf, 1997). The servant leader is a leader who is driven by his or her followers, as leadership involves a leader serving his or her followers first and foremost (Greenleaf, 1977). The leader takes on a role that is supportive and contributes to their personal as well as their professional achievements (Smith, Montagno and Kuzmenko, 2004). A questionnaire consisting of 27 questions was drafted, of which were four demographic questions. A 5-point Likert Scale was used in order for the participants to respond to the questions. The questionnaire was drawn from a number of questionnaires available in literature on leadership and adapted to suit Rhodes University sports clubs. The questionnaire was distributed personally by the researcher, as well as through an online questionnaire. There were a total of 153 candidates who participated in the study. Descriptive statistics were used to analyse the data. The majority of the respondents had the perceptions that their chairperson displayed characteristics of a servant leader. Majority of the participants were in agreement of the questions asked in the questionnaire, which focused on many servant leadership qualities. The results will be handed over to the Head of Sports Administration in order for them to get an idea of their leaders’ characteristics and areas where they can improve upon.
- Full Text:
- Date Issued: 2016
- Authors: Stiebel, Jessica Lee
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:872 , http://hdl.handle.net/10962/d1021317
- Description: This research investigates the level of servant leadership within Rhodes University sport clubs. The goals of this research are to assess the perception the club members have of their chairperson and to key identify areas of development. The sport clubs at Rhodes University are partially run by chairpersons who are voted into the position by his or her peers of a sports club. The chairpersons work alongside Rhodes University employees who are a part of the Sports Administration team to oversee the running, scheduling and finances of the club. The sports clubs are representative of Rhodes University and it is the chairperson’s responsibility to ensure the club is lead and run effectively. Robert Greenleaf coined the term servant leader in the 1970s (Greenleaf, 1997). The servant leader is a leader who is driven by his or her followers, as leadership involves a leader serving his or her followers first and foremost (Greenleaf, 1977). The leader takes on a role that is supportive and contributes to their personal as well as their professional achievements (Smith, Montagno and Kuzmenko, 2004). A questionnaire consisting of 27 questions was drafted, of which were four demographic questions. A 5-point Likert Scale was used in order for the participants to respond to the questions. The questionnaire was drawn from a number of questionnaires available in literature on leadership and adapted to suit Rhodes University sports clubs. The questionnaire was distributed personally by the researcher, as well as through an online questionnaire. There were a total of 153 candidates who participated in the study. Descriptive statistics were used to analyse the data. The majority of the respondents had the perceptions that their chairperson displayed characteristics of a servant leader. Majority of the participants were in agreement of the questions asked in the questionnaire, which focused on many servant leadership qualities. The results will be handed over to the Head of Sports Administration in order for them to get an idea of their leaders’ characteristics and areas where they can improve upon.
- Full Text:
- Date Issued: 2016
An investigation of the aquatic macroinvertebrate fauna of the southern Great Escarpment (South Africa): insights from ecological and genetic studies
- Authors: Taylor, Chantal Lee
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4275 , http://hdl.handle.net/10962/d1020839
- Description: Biological diversity in freshwater biomes is vital to maintain healthy, functioning ecosystems with resilience to disturbance and the impacts of climate change. Freshwater ecosystems provide essential resources to life on Earth. However, as increasing pressure is being placed on the environment by human population growth, the quality of freshwater resources and the health of these ecosystems are at risk. Mountain streams provide an important source of water and are usually less affected by anthropogenic stressors, compared to lowland freshwaters. These montane streams are therefore of important conservation value and due to their untransformed nature serve as ideal ecosystems for biodiversity studies and as reference sites for studies on environmental change. This study explores aquatic macroinvertebrate biodiversity of the southern Great Escarpment in South Africa. Species assemblages and the environmental variables of each site were sampled from first order streams across five different mountain blocks along the Great Escarpment. Additionally, mitochondrial DNA of three mayfly species (Afroptilum sudafricanum, Demoreptus natalensis and Demoreptus capensis), commonly occurring in the study area, was analysed to compare the genetic diversity between habitat specialist and habitat generalist species. A total of 2 595 macroinvertebrate specimens from 47 families and 86 species were collected with several interesting and potentially new species being discovered. Partitioned diversity analyses indicate that macroinvertebrate diversity varies across mountain blocks. Multivariate analyses indicate that differences in assemblages could be attributed to differences in environmental variables between sites, particularly water velocity, total dissolved solids and salinity. As these environmental variables reflect of the topography of the sites, differences in species assemblages was attributed to difference in topography and therefore biotopes present. Habitat-restricted mayfly species (D. natalensis and D. capensis), occur in distinct populations confined to mountains blocks. Isolation-by-distance analyses further emphasis that these species are genetically restricted by their habitat preference for mountain streams. In contrast, A. sudafricanum, a habitat generalist, showed no indication of genetic structure due to location or distance. Possible cryptic taxa and new species were identified within A. sudafricanum and Dermoreptus respectively. This study provides an important contribution to the baseline data of freshwater macroinvertebrate diversity for the southern Great Escarpment region and provides insights into the considerable genetic diversity of selected aquatic taxa across this region.
- Full Text:
- Date Issued: 2016
- Authors: Taylor, Chantal Lee
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4275 , http://hdl.handle.net/10962/d1020839
- Description: Biological diversity in freshwater biomes is vital to maintain healthy, functioning ecosystems with resilience to disturbance and the impacts of climate change. Freshwater ecosystems provide essential resources to life on Earth. However, as increasing pressure is being placed on the environment by human population growth, the quality of freshwater resources and the health of these ecosystems are at risk. Mountain streams provide an important source of water and are usually less affected by anthropogenic stressors, compared to lowland freshwaters. These montane streams are therefore of important conservation value and due to their untransformed nature serve as ideal ecosystems for biodiversity studies and as reference sites for studies on environmental change. This study explores aquatic macroinvertebrate biodiversity of the southern Great Escarpment in South Africa. Species assemblages and the environmental variables of each site were sampled from first order streams across five different mountain blocks along the Great Escarpment. Additionally, mitochondrial DNA of three mayfly species (Afroptilum sudafricanum, Demoreptus natalensis and Demoreptus capensis), commonly occurring in the study area, was analysed to compare the genetic diversity between habitat specialist and habitat generalist species. A total of 2 595 macroinvertebrate specimens from 47 families and 86 species were collected with several interesting and potentially new species being discovered. Partitioned diversity analyses indicate that macroinvertebrate diversity varies across mountain blocks. Multivariate analyses indicate that differences in assemblages could be attributed to differences in environmental variables between sites, particularly water velocity, total dissolved solids and salinity. As these environmental variables reflect of the topography of the sites, differences in species assemblages was attributed to difference in topography and therefore biotopes present. Habitat-restricted mayfly species (D. natalensis and D. capensis), occur in distinct populations confined to mountains blocks. Isolation-by-distance analyses further emphasis that these species are genetically restricted by their habitat preference for mountain streams. In contrast, A. sudafricanum, a habitat generalist, showed no indication of genetic structure due to location or distance. Possible cryptic taxa and new species were identified within A. sudafricanum and Dermoreptus respectively. This study provides an important contribution to the baseline data of freshwater macroinvertebrate diversity for the southern Great Escarpment region and provides insights into the considerable genetic diversity of selected aquatic taxa across this region.
- Full Text:
- Date Issued: 2016
An investigation of the barriers and drivers to CDM renewable energy investment at the Metro, Kouga and Jeffreys Bay windfarms
- Authors: Staples, Daryl Nolan
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:871 , http://hdl.handle.net/10962/d1021316
- Description: This research is presented in three sections. Section 1 presents the research report in an academic journal article format. Section 2 provides a comprehensive literature review and Section 3 describes the research methodology and methods employed during the research. Climate change is the most urgent challenge facing planet earth today. The Intergovernmental Panel on Climate Change (IPCC) fifth assessment report (AR5) clearly states, “Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems” (IPCC, 2014:2). The Renewable Energy Policy Network for the 21st Century (REN21) published the 10th annual edition of the Renewables 2015 Global Status Report, which illustrates the importance of a zero emissions energy sector (REN21, 2015). Despite the world’s average annual 1,5% increase in energy consumption in recent years, and average 3% growth in Gross Domestic Product, carbon dioxide (CO2) emissions in 2014 were unchanged from 2013 levels (REN21, 2015). The report findings state, “For the first time in four decades, the world economy grew without a parallel rise in CO2 emissions” (REN21, 2015:17). Renewable energy and improved energy efficiency is key to limiting global warming and avoiding dangerous impacts from climate change (REN21, 2015). With a view to the successful outcome of the 21st Conference of the Parties (COP21) in December 2015, renewable energy could contribute significantly in mitigating climate change and supporting the Sustainable Development Goals (SDGs), specifically SDG 7, on Sustainable Energy for All (SAIREC, 2015). South Africa has been rated the 15th most attractive destination for investment in the renewable energy sector and could become a renewable energy leader in the African continent, according to the Renewable Energy Country Attractiveness Index of EY (Ernest and Young) (EY, 2015). And more...
- Full Text:
- Date Issued: 2016
- Authors: Staples, Daryl Nolan
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:871 , http://hdl.handle.net/10962/d1021316
- Description: This research is presented in three sections. Section 1 presents the research report in an academic journal article format. Section 2 provides a comprehensive literature review and Section 3 describes the research methodology and methods employed during the research. Climate change is the most urgent challenge facing planet earth today. The Intergovernmental Panel on Climate Change (IPCC) fifth assessment report (AR5) clearly states, “Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems” (IPCC, 2014:2). The Renewable Energy Policy Network for the 21st Century (REN21) published the 10th annual edition of the Renewables 2015 Global Status Report, which illustrates the importance of a zero emissions energy sector (REN21, 2015). Despite the world’s average annual 1,5% increase in energy consumption in recent years, and average 3% growth in Gross Domestic Product, carbon dioxide (CO2) emissions in 2014 were unchanged from 2013 levels (REN21, 2015). The report findings state, “For the first time in four decades, the world economy grew without a parallel rise in CO2 emissions” (REN21, 2015:17). Renewable energy and improved energy efficiency is key to limiting global warming and avoiding dangerous impacts from climate change (REN21, 2015). With a view to the successful outcome of the 21st Conference of the Parties (COP21) in December 2015, renewable energy could contribute significantly in mitigating climate change and supporting the Sustainable Development Goals (SDGs), specifically SDG 7, on Sustainable Energy for All (SAIREC, 2015). South Africa has been rated the 15th most attractive destination for investment in the renewable energy sector and could become a renewable energy leader in the African continent, according to the Renewable Energy Country Attractiveness Index of EY (Ernest and Young) (EY, 2015). And more...
- Full Text:
- Date Issued: 2016
An investigation of the history and works of the Keiskamma Art Project
- Authors: Osner, Heather
- Date: 2016
- Subjects: Community arts projects -- South Africa -- Eastern Cape , Artists and community -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/13038 , vital:27146
- Description: This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty stricken communities in South Africa. This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty-stricken communities in South Africa.This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty stricken communities in South Africa.This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty stricken communities in South Africa.
- Full Text:
- Date Issued: 2016
- Authors: Osner, Heather
- Date: 2016
- Subjects: Community arts projects -- South Africa -- Eastern Cape , Artists and community -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/13038 , vital:27146
- Description: This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty stricken communities in South Africa. This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty-stricken communities in South Africa.This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty stricken communities in South Africa.This research study focusses on how and why Carol Hofmeyr began the Keiskamma Art Project in Hamburg, Eastern Cape, as well as the development of the project’s infrastructure, history and detailed business practices and how it has evolved. A chronological detailed pictorial record has been drawn up of the major/monumental works it has produced, its achievements, awards and the accolades it has won. The recurrent narrative themes of HIV/AIDS, Nguni cattle, the Nongquawuse story, local birds, plants and fish which are also discussed. A comparable study, comparing the business practices of the Keiskamma Art Project with the research of Professor Ingrid Stevens on Morris & Co and five other successful, sustained South African Art Projects. Data has been tabulated in an effort to recognise the variances, similarities and differences in an effort to identify a “best practise” business model. Such a model may assist in the development of further art projects, so as to uplift other poverty stricken communities in South Africa.
- Full Text:
- Date Issued: 2016
An investigation of the morphological and electrochemical properties of spinel cathode oxide materials used in li-ion batteries
- Authors: Snyders, Charmelle
- Date: 2016
- Subjects: Lithium ion batteries Cathodes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12929 , vital:27135
- Description: Li-ion batteries have become the more dominant battery type used in portable electronic devices such as cell phones, computers and more recently their application in full electric vehicles (EV). Li-ion batteries have many advantages over the traditional rechargeable systems (Pb-acid and Ni-MH) such as their higher energy density, low self-discharge, long capacity cycle life and relatively maintenance free. Due to their commercial advantages, a lot of research is done in developing new novel Li-ion electrode materials, improving existing ones and to reduce manufacturing costs in order to make them more cost effective in their applications. This study looked at the cathode material chemistry that has a typical spinel manganese oxide (LiMn2O4) type structure. For comparison the study also considered the influence of doping the phase with various metals such as Al, Mg, Co and Ni that were made as precursors using various carboxylic acids (Citric, Ascorbic, Succinic and Poly-acrylic acid) from a sol-gel process. Traditional batch methods of synthesizing the electrode material is costly and do not necessarily provide optimized electrochemical performance. Alternative continuous less energy intensive methods would help reduce the costs of the preparation of the electrode materials. This study investigated the influence of two synthesis techniques on the materials physical and electrochemical characteristics. These synthesis methods included the use of a typical batch sol-gel method and the continuous spray-drying technique. The spinel materials were prepared and characterized by Powder X-Ray Diffraction (PXRD) to confirm the formation of various phases during the synthesis process. In addition, in-situ PXRD techniques were used to track the phase changes that occurred in the typical batch synthesis process from a sol-gel mixture to the final crystalline spinel oxide. The materials were also characterized by thermal gravimetric analysis (TGA), whereby the materials decomposition mechanisms were observed as the precursor was gradually heated to the final oxide. These synthesized materials prepared under various conditions were then used to build suitable Li-ion coin type of cells, whereby their electrochemical properties were tested by simple capacity tests and electrochemical impedance spectroscopy (EIS). EIS measurements were done on the built cells with the various materials at various charge voltages. TG analysis showed that the materials underwent multiple decomposition steps upon heating for the doped lithium manganese oxides, whereas the undoped oxide showed only a single decomposition step. The results showed that all the materials achieved their weight loss below 400 °C, and that the final spinel oxide had already formed. The in-situ PXRD analysis showed the progression of the phase transitions where certain of the materials changed from a crystalline precursor to an amorphous intermediate phase and then finally to the spinel cathode oxide (Li1.03Mg0.2Mn1.77O4, and LiCo1.09Mn0.91O4). For other materials, the precursor would start as an amorphous phase, and then upon heating, convert into an impure intermediate phase (Mn2O3) before forming the final spinel oxide (Li1.03Mn1.97O4 and LiNi0.5Mn1.5O4). The in-situ study also showed the increases in the materials respective lattice parameters of the crystalline unit cells upon heating and the significant increases in their crystallite sizes when heated above 600 °C. Hence the results implied that a type of sintering of the particles would occur at temperatures above 600 °C, thereby increasing the respective crystallite size. The study showed that the cathode active materials made by the sol-gel spray-drying method would give a material that had a significantly larger surface area and a smaller crystallite size when compared to the materials made by the batch process. The electrochemical analysis showed that there was only a slight increase in the discharge capacities of the cells made with the spray-drying technique when compared to the cells made with the materials from the batch sol-gel technique. Whereas, the EIS study showed that there were distinct differences in the charging behavior of the cells made with the various materials using different synthesis techniques. The EIS results showed that there was a general decrease in the cells charge transfer resistance (Rct) as the charge potential increased regardless of the synthesis method used for the various materials. The results also showed that the lithium-ion diffusion coefficient (DLi) obtained from EIS measurements were in most of the samples higher for the cathode materials that had a larger surface area. This implied that the Li-ion could diffuse at a faster rate through the bulk material. The study concluded that by optimizing the synthesis process in terms of the careful control of the thermal parameters, the Li-ion batteries‟ cathode active material of the manganese spinel type could be optimized and be manufactured by using a continuous flow micro spray process.
- Full Text:
- Date Issued: 2016
- Authors: Snyders, Charmelle
- Date: 2016
- Subjects: Lithium ion batteries Cathodes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12929 , vital:27135
- Description: Li-ion batteries have become the more dominant battery type used in portable electronic devices such as cell phones, computers and more recently their application in full electric vehicles (EV). Li-ion batteries have many advantages over the traditional rechargeable systems (Pb-acid and Ni-MH) such as their higher energy density, low self-discharge, long capacity cycle life and relatively maintenance free. Due to their commercial advantages, a lot of research is done in developing new novel Li-ion electrode materials, improving existing ones and to reduce manufacturing costs in order to make them more cost effective in their applications. This study looked at the cathode material chemistry that has a typical spinel manganese oxide (LiMn2O4) type structure. For comparison the study also considered the influence of doping the phase with various metals such as Al, Mg, Co and Ni that were made as precursors using various carboxylic acids (Citric, Ascorbic, Succinic and Poly-acrylic acid) from a sol-gel process. Traditional batch methods of synthesizing the electrode material is costly and do not necessarily provide optimized electrochemical performance. Alternative continuous less energy intensive methods would help reduce the costs of the preparation of the electrode materials. This study investigated the influence of two synthesis techniques on the materials physical and electrochemical characteristics. These synthesis methods included the use of a typical batch sol-gel method and the continuous spray-drying technique. The spinel materials were prepared and characterized by Powder X-Ray Diffraction (PXRD) to confirm the formation of various phases during the synthesis process. In addition, in-situ PXRD techniques were used to track the phase changes that occurred in the typical batch synthesis process from a sol-gel mixture to the final crystalline spinel oxide. The materials were also characterized by thermal gravimetric analysis (TGA), whereby the materials decomposition mechanisms were observed as the precursor was gradually heated to the final oxide. These synthesized materials prepared under various conditions were then used to build suitable Li-ion coin type of cells, whereby their electrochemical properties were tested by simple capacity tests and electrochemical impedance spectroscopy (EIS). EIS measurements were done on the built cells with the various materials at various charge voltages. TG analysis showed that the materials underwent multiple decomposition steps upon heating for the doped lithium manganese oxides, whereas the undoped oxide showed only a single decomposition step. The results showed that all the materials achieved their weight loss below 400 °C, and that the final spinel oxide had already formed. The in-situ PXRD analysis showed the progression of the phase transitions where certain of the materials changed from a crystalline precursor to an amorphous intermediate phase and then finally to the spinel cathode oxide (Li1.03Mg0.2Mn1.77O4, and LiCo1.09Mn0.91O4). For other materials, the precursor would start as an amorphous phase, and then upon heating, convert into an impure intermediate phase (Mn2O3) before forming the final spinel oxide (Li1.03Mn1.97O4 and LiNi0.5Mn1.5O4). The in-situ study also showed the increases in the materials respective lattice parameters of the crystalline unit cells upon heating and the significant increases in their crystallite sizes when heated above 600 °C. Hence the results implied that a type of sintering of the particles would occur at temperatures above 600 °C, thereby increasing the respective crystallite size. The study showed that the cathode active materials made by the sol-gel spray-drying method would give a material that had a significantly larger surface area and a smaller crystallite size when compared to the materials made by the batch process. The electrochemical analysis showed that there was only a slight increase in the discharge capacities of the cells made with the spray-drying technique when compared to the cells made with the materials from the batch sol-gel technique. Whereas, the EIS study showed that there were distinct differences in the charging behavior of the cells made with the various materials using different synthesis techniques. The EIS results showed that there was a general decrease in the cells charge transfer resistance (Rct) as the charge potential increased regardless of the synthesis method used for the various materials. The results also showed that the lithium-ion diffusion coefficient (DLi) obtained from EIS measurements were in most of the samples higher for the cathode materials that had a larger surface area. This implied that the Li-ion could diffuse at a faster rate through the bulk material. The study concluded that by optimizing the synthesis process in terms of the careful control of the thermal parameters, the Li-ion batteries‟ cathode active material of the manganese spinel type could be optimized and be manufactured by using a continuous flow micro spray process.
- Full Text:
- Date Issued: 2016
An investigation of the practices employed by an environmental community-based organization to successfully sustain its school based and community based projects (A case study)
- Authors: Hlophe, Nomalanga Nokuthula
- Date: 2016
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2073 , http://hdl.handle.net/10962/d1021252
- Description: Community-based organizations (CBOs) play a crucial role in sustainable development and hence it is important that they are promoted, guided and supported by state agencies and the private sector. The South African government encourages communities to establish co-operatives as a tool or strategy to address local social issues and risks and act accordingly. The purpose of this case study was to determine what aspects of the establishment and operation of a successful community-based environmental organization are producing sustained school and community projects. The study set out to investigate and audit the activities of a successful environmental CBO so as to determine how it has successfully sustained its school and community environmental projects. The reason for this investigation was to inform other CBOs and the state environmental agencies that support them on how to sustain their environmental activities in community and school contexts. The investigation was designed as an interpretive case study, which used document analysis, semi-structured interviews and observations to gather data. The gathered data was analyzed through inductive analysis to interpret and audit reported activities. Analytical memos were used to represent key themes in relation to the successful operations of the organization. Through auditing and reporting the activities in the analytical memos, analytical statements were developed. Those statements guided the discussion and informed the study‟s findings and recommendations. After investigating this CBO, it was concluded that, their success is a result of the establishment of a networking forum with different stakeholders and parties, community involvement in different projects, partnerships with local schools to develop and expand their curriculum practice, CBO networking locally and internationally and finally, their participation in annual and continuous environmental competitions/projects/programs. The insights gained and lessons learned will be used to advice and support community based co-operatives in environmental learning activities in school and community contexts as part of my ongoing work.
- Full Text:
- Date Issued: 2016
- Authors: Hlophe, Nomalanga Nokuthula
- Date: 2016
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2073 , http://hdl.handle.net/10962/d1021252
- Description: Community-based organizations (CBOs) play a crucial role in sustainable development and hence it is important that they are promoted, guided and supported by state agencies and the private sector. The South African government encourages communities to establish co-operatives as a tool or strategy to address local social issues and risks and act accordingly. The purpose of this case study was to determine what aspects of the establishment and operation of a successful community-based environmental organization are producing sustained school and community projects. The study set out to investigate and audit the activities of a successful environmental CBO so as to determine how it has successfully sustained its school and community environmental projects. The reason for this investigation was to inform other CBOs and the state environmental agencies that support them on how to sustain their environmental activities in community and school contexts. The investigation was designed as an interpretive case study, which used document analysis, semi-structured interviews and observations to gather data. The gathered data was analyzed through inductive analysis to interpret and audit reported activities. Analytical memos were used to represent key themes in relation to the successful operations of the organization. Through auditing and reporting the activities in the analytical memos, analytical statements were developed. Those statements guided the discussion and informed the study‟s findings and recommendations. After investigating this CBO, it was concluded that, their success is a result of the establishment of a networking forum with different stakeholders and parties, community involvement in different projects, partnerships with local schools to develop and expand their curriculum practice, CBO networking locally and internationally and finally, their participation in annual and continuous environmental competitions/projects/programs. The insights gained and lessons learned will be used to advice and support community based co-operatives in environmental learning activities in school and community contexts as part of my ongoing work.
- Full Text:
- Date Issued: 2016
An investigation of the teaching strategies employed by a selection of educators at an FET college to support at risk L2 tourism students
- Authors: Tsotso, Nosipho
- Date: 2016
- Subjects: Critical thinking -- Study and teaching , Vocational education -- Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10948/7225 , vital:21310
- Description: The South African education system is based on learner centred principles and encourages the development of critical thinking. This approach is reflected in the South African Qualifications Framework, which identifies critical thinking as a primary outcome of education. In the vocational Tourism programme, there is a link between the subject learning outcomes and critical crossfield outcomes. The role of the vocational college educator is central in facilitating the development of critical thinking skills of all learners. The purpose of this study was to investigate how the selected Tourism educators develop critical thinking skills of risk L2 students. I conducted the study in a selected FET College using a qualitative case study in order to gain deeper understanding of how the educators implement curriculum policy in their classrooms. This study used four data collection instruments to gain an in-depth understanding of the research topic. The findings of the study reveal that educators understand the value of teaching critical thinking. However, there is a gap between educators’ conceptual understanding of critical thinking and their instructional practice to develop critical thinking skills during classroom instruction. The findings also reveal that there are factors that hinder the development of at risk students’ critical thinking skills such as; limited English language proficiency, poor behaviour, and subject guidelines which do not provide educators with guidance on teaching critical thinking skills. The study recommends in-service training sessions that will support educators on how to teach critical thinking skills explicitly. This study also recommends the development of practical guidelines to enhance educators’ critical thinking teaching strategies. The findings of this research will assist me in improving the support that I provide to Tourism educators.
- Full Text:
- Date Issued: 2016
- Authors: Tsotso, Nosipho
- Date: 2016
- Subjects: Critical thinking -- Study and teaching , Vocational education -- Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10948/7225 , vital:21310
- Description: The South African education system is based on learner centred principles and encourages the development of critical thinking. This approach is reflected in the South African Qualifications Framework, which identifies critical thinking as a primary outcome of education. In the vocational Tourism programme, there is a link between the subject learning outcomes and critical crossfield outcomes. The role of the vocational college educator is central in facilitating the development of critical thinking skills of all learners. The purpose of this study was to investigate how the selected Tourism educators develop critical thinking skills of risk L2 students. I conducted the study in a selected FET College using a qualitative case study in order to gain deeper understanding of how the educators implement curriculum policy in their classrooms. This study used four data collection instruments to gain an in-depth understanding of the research topic. The findings of the study reveal that educators understand the value of teaching critical thinking. However, there is a gap between educators’ conceptual understanding of critical thinking and their instructional practice to develop critical thinking skills during classroom instruction. The findings also reveal that there are factors that hinder the development of at risk students’ critical thinking skills such as; limited English language proficiency, poor behaviour, and subject guidelines which do not provide educators with guidance on teaching critical thinking skills. The study recommends in-service training sessions that will support educators on how to teach critical thinking skills explicitly. This study also recommends the development of practical guidelines to enhance educators’ critical thinking teaching strategies. The findings of this research will assist me in improving the support that I provide to Tourism educators.
- Full Text:
- Date Issued: 2016
An investigation on the effect of Russian wheat aphid (Diuraphis noxia Kurdjumov) population growth and feeding damage on selected barley (Hordeum vulgare L.) cultivars under ambient and elevated CO2
- Authors: Sacranie, Sattar Farouk
- Date: 2016
- Subjects: Russian wheat aphid -- Research -- South Africa Barley -- Disease and pest resistance -- South Africa Callose Aphids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50311 , vital:25975
- Description: The Russian wheat aphid (RWA) (Diuraphis noxia Kurdjumov) is a major pest of cultivated small grains. It is particularly devastating because of is high reproductive rate which results in the growth of large populations which become damaging to its host plants. Development of resistant barley (Hordeum vulgare L.) cultivars is complicated as resistance is polygenic. As a result, the industry remains at risk now that the RWA has spread throughout South Africa. It has, as recently as, 2013, been identified in the SW Cape, which was previously geographically isolated. This is South Africa‟s principle barley growing region. Now a potentially huge problem exists. Therefore, it is imperative that an alternative to pesticide use is found. Testing potential innate resistance in barley cultivars is thus, critical. In this thesis, I present data on four barely cultivars where I have examined their resistance/ lack of resistance to three known RWA biotypes, RWASA1, RWASA2 and RWASA3. The barley varieties used were two economically important South African malt barley cultivars (S5 and SSG 564) along with two potentially RWA resistant Afghan accessions (CIho 4125 and CIho 4159). The RWA biotype population growth rates on each of the plants were determined over a 14 day period. The aim was to establish baseline data of the effects of RWA population growth on the host plants under ambient CO2 (380 – 400 ppm) conditions. The extent of RWA feeding damage was investigated at the cell level by examining saliva deposition and cell disruption using Transmission Electron Microscopy; at the tissue/vascular level using fluorescence microscopy, to determine the extent of callose formation; at a whole leaf level by recording percent chlorosis and leaf roll; and finally, at a whole plant level by measuring biomass loss.The experiments were repeated under elevated CO2 (450 ppm) to model any changes in RWA/plant interaction with respect to future climate change. The effects of an elevated CO2 environment and RWA feeding on host plant foliar N and C:N ratio were compared to ambient CO2 conditions, to provide a clearer picture of the potential nutrient drain that a feeding RWA colony exacts on its host. Of the varieties tested, the CIho accessions performed better than the two SA barley cultivars as the CIho accessions appeared to express a mild antibiosis resistance response as RWA populations, particularly those of RWASA1, were smaller than those observed on either S5 or SSG 564. In addition, less damage was evident in the two CIho accessions due to RWA feeding. II RWASA2 was the most virulent of the three RWA biotypes tested, followed by RWASA3 while RWASA1 was the least virulent. Under elevated CO2 conditions, RWA feeding damage was exacerbated but the trend of biotype virulence remained the same. Higher aphid population sizes were recorded under elevated CO2, meant that even the more resistant CIho accessions were overcome by the increased demand made by the larger aphid colonies on the host plants. The % foliar N data showed that under elevated CO2 aphid-free control plants had increased N levels in their leaves. Increased “food” supply (as shown by the increased N levels) therefore allowed significantly larger aphid populations to develop on the plants exposed to elevated CO2, due to improved nutrient status of the phloem sap taken up by RWA. The knock-on effect of a higher aphid population was increased cell disruption as a result of extensive probing, extensive formations of wound callose, with the result that phloem damage impeded nutrient flow through the vascular tissues which contributed to chlorosis and (eventually plant) death. The major conclusion from this study is that even a mild CO2 elevation resulted in an increase aphid population which may pose a severe and very real threat to a barley crop. Therefore, without effort to identify and deploy resistant barley cultivars, it could well be possible that future barley cultivation in South Africa may no longer be viable.
- Full Text:
- Date Issued: 2016
- Authors: Sacranie, Sattar Farouk
- Date: 2016
- Subjects: Russian wheat aphid -- Research -- South Africa Barley -- Disease and pest resistance -- South Africa Callose Aphids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50311 , vital:25975
- Description: The Russian wheat aphid (RWA) (Diuraphis noxia Kurdjumov) is a major pest of cultivated small grains. It is particularly devastating because of is high reproductive rate which results in the growth of large populations which become damaging to its host plants. Development of resistant barley (Hordeum vulgare L.) cultivars is complicated as resistance is polygenic. As a result, the industry remains at risk now that the RWA has spread throughout South Africa. It has, as recently as, 2013, been identified in the SW Cape, which was previously geographically isolated. This is South Africa‟s principle barley growing region. Now a potentially huge problem exists. Therefore, it is imperative that an alternative to pesticide use is found. Testing potential innate resistance in barley cultivars is thus, critical. In this thesis, I present data on four barely cultivars where I have examined their resistance/ lack of resistance to three known RWA biotypes, RWASA1, RWASA2 and RWASA3. The barley varieties used were two economically important South African malt barley cultivars (S5 and SSG 564) along with two potentially RWA resistant Afghan accessions (CIho 4125 and CIho 4159). The RWA biotype population growth rates on each of the plants were determined over a 14 day period. The aim was to establish baseline data of the effects of RWA population growth on the host plants under ambient CO2 (380 – 400 ppm) conditions. The extent of RWA feeding damage was investigated at the cell level by examining saliva deposition and cell disruption using Transmission Electron Microscopy; at the tissue/vascular level using fluorescence microscopy, to determine the extent of callose formation; at a whole leaf level by recording percent chlorosis and leaf roll; and finally, at a whole plant level by measuring biomass loss.The experiments were repeated under elevated CO2 (450 ppm) to model any changes in RWA/plant interaction with respect to future climate change. The effects of an elevated CO2 environment and RWA feeding on host plant foliar N and C:N ratio were compared to ambient CO2 conditions, to provide a clearer picture of the potential nutrient drain that a feeding RWA colony exacts on its host. Of the varieties tested, the CIho accessions performed better than the two SA barley cultivars as the CIho accessions appeared to express a mild antibiosis resistance response as RWA populations, particularly those of RWASA1, were smaller than those observed on either S5 or SSG 564. In addition, less damage was evident in the two CIho accessions due to RWA feeding. II RWASA2 was the most virulent of the three RWA biotypes tested, followed by RWASA3 while RWASA1 was the least virulent. Under elevated CO2 conditions, RWA feeding damage was exacerbated but the trend of biotype virulence remained the same. Higher aphid population sizes were recorded under elevated CO2, meant that even the more resistant CIho accessions were overcome by the increased demand made by the larger aphid colonies on the host plants. The % foliar N data showed that under elevated CO2 aphid-free control plants had increased N levels in their leaves. Increased “food” supply (as shown by the increased N levels) therefore allowed significantly larger aphid populations to develop on the plants exposed to elevated CO2, due to improved nutrient status of the phloem sap taken up by RWA. The knock-on effect of a higher aphid population was increased cell disruption as a result of extensive probing, extensive formations of wound callose, with the result that phloem damage impeded nutrient flow through the vascular tissues which contributed to chlorosis and (eventually plant) death. The major conclusion from this study is that even a mild CO2 elevation resulted in an increase aphid population which may pose a severe and very real threat to a barley crop. Therefore, without effort to identify and deploy resistant barley cultivars, it could well be possible that future barley cultivation in South Africa may no longer be viable.
- Full Text:
- Date Issued: 2016
An overview of language policy implementation in the City of Tswane Metropolitan Municipality with a focus on translation as an activity of language policy implementation
- Seshoka, Keaobaka Omphile Precious
- Authors: Seshoka, Keaobaka Omphile Precious
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/932 , vital:20004
- Description: The South African Municipality Systems Act (2000) states that language should not act as a barrier of access for citizens with no or limited proficiency in English to municipal services, or in ensuring the right of citizens to participate in, and contribute to the social, cultural, intellectual, economic and political life of South African society. In that regard, it recommends that South African municipalities develop a culture of public participation by providing services in a language preferred and used by citizens within their municipality through translation, amongst other things. This study examines how the translation services, as articulated in the language policy and plan of the City of Tshwane Metropolitan Municipality, is used as a language implementation strategy and in facilitating public participation. It further assesses the quality of the translated information accessed by the different residents of the City of Tshwane Metropolitan Municipality against theories of translation appraisal. The main focus area of this research is on extent of the use of translation as an activity of corpus planning, to facilitate language policy implementation in the City of Tshwane Municipality to enable better public participation. It is hoped that the study will be able to give policy makers and those tasked with implementation, especially at government municipalities‘ strategies to assess and determine the state of translation services to improve functionality, quality and the extent to which translation activities contribute to corpus planning.
- Full Text:
- Date Issued: 2016
- Authors: Seshoka, Keaobaka Omphile Precious
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/932 , vital:20004
- Description: The South African Municipality Systems Act (2000) states that language should not act as a barrier of access for citizens with no or limited proficiency in English to municipal services, or in ensuring the right of citizens to participate in, and contribute to the social, cultural, intellectual, economic and political life of South African society. In that regard, it recommends that South African municipalities develop a culture of public participation by providing services in a language preferred and used by citizens within their municipality through translation, amongst other things. This study examines how the translation services, as articulated in the language policy and plan of the City of Tshwane Metropolitan Municipality, is used as a language implementation strategy and in facilitating public participation. It further assesses the quality of the translated information accessed by the different residents of the City of Tshwane Metropolitan Municipality against theories of translation appraisal. The main focus area of this research is on extent of the use of translation as an activity of corpus planning, to facilitate language policy implementation in the City of Tshwane Municipality to enable better public participation. It is hoped that the study will be able to give policy makers and those tasked with implementation, especially at government municipalities‘ strategies to assess and determine the state of translation services to improve functionality, quality and the extent to which translation activities contribute to corpus planning.
- Full Text:
- Date Issued: 2016
An overview of linux container based network emulation
- Peach, Schalk, Irwin, Barry V W, van Heerden, Renier
- Authors: Peach, Schalk , Irwin, Barry V W , van Heerden, Renier
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430095 , vital:72665 , https://www.proceedings.com/30838.html
- Description: The objective of this paper is to assess the current state of Container-Based Emulator implementations on the Linux platform. Through a nar-rative overview, a selection of open source Container-Based emulators are analysed to collect information regarding the technologies used to construct them to assess the current state of this emerging technology. Container-Based Emulators allows the creation of small emulated net-works on commodity hardware through the use of kernel level virtualiza-tion techniques, also referred to as containerisation. Container-Based Emulators act as a management tool to control containers and the ap-plications that execute within them. The ability of Container Based Emu-lators to create repeatable and controllable test networks makes it ideal for use as training and experimentation tools in the information security and network management fields. Due to the ease of use and low hard-ware requirements, the tools present a low cost alternative to other forms of network experimentation platforms. Through a review of cur-rent literature and source code, the current state of Container-Based Emulators is assessed.
- Full Text:
- Date Issued: 2016
- Authors: Peach, Schalk , Irwin, Barry V W , van Heerden, Renier
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430095 , vital:72665 , https://www.proceedings.com/30838.html
- Description: The objective of this paper is to assess the current state of Container-Based Emulator implementations on the Linux platform. Through a nar-rative overview, a selection of open source Container-Based emulators are analysed to collect information regarding the technologies used to construct them to assess the current state of this emerging technology. Container-Based Emulators allows the creation of small emulated net-works on commodity hardware through the use of kernel level virtualiza-tion techniques, also referred to as containerisation. Container-Based Emulators act as a management tool to control containers and the ap-plications that execute within them. The ability of Container Based Emu-lators to create repeatable and controllable test networks makes it ideal for use as training and experimentation tools in the information security and network management fields. Due to the ease of use and low hard-ware requirements, the tools present a low cost alternative to other forms of network experimentation platforms. Through a review of cur-rent literature and source code, the current state of Container-Based Emulators is assessed.
- Full Text:
- Date Issued: 2016
An unsung dialogue: music, society and the history of The Flames
- Authors: Park, Duncan Keith
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193645 , vital:45376
- Description: This research aims to examine the relationship between music and social conditions within the context of apartheid. The focus area is the city of Durban, specifically 1960-1970. A case study of the multi-racial Durban-based band, The Flames (1963 – 1972) will be used to rigorously assess the extent to which social conditions and music can affect each other in both directions. This will also be the first coherent and historical narrative of the band, The Flames. As such, the thesis aims to make an original contribution to this field of music history, while it will provide the very first academic discussion of The Flames. , Thesis (MA) -- Faculty of Humanities, History, 2016
- Full Text:
- Date Issued: 2016
- Authors: Park, Duncan Keith
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193645 , vital:45376
- Description: This research aims to examine the relationship between music and social conditions within the context of apartheid. The focus area is the city of Durban, specifically 1960-1970. A case study of the multi-racial Durban-based band, The Flames (1963 – 1972) will be used to rigorously assess the extent to which social conditions and music can affect each other in both directions. This will also be the first coherent and historical narrative of the band, The Flames. As such, the thesis aims to make an original contribution to this field of music history, while it will provide the very first academic discussion of The Flames. , Thesis (MA) -- Faculty of Humanities, History, 2016
- Full Text:
- Date Issued: 2016
Analysis of non-peptidic compounds as potential malarial inhibitors against plasmodial cysteine proteases via integrated virtual screening workflow
- Musyoka, Thommas M, Kanzi, Aquillah M, Lobb, Kevin A, Tastan Bishop, Özlem
- Authors: Musyoka, Thommas M , Kanzi, Aquillah M , Lobb, Kevin A , Tastan Bishop, Özlem
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123074 , vital:35403 , https://doi.10.1080/07391102.2015.1108231
- Description: Malaria is an infectious disease caused by a diverse group of erythrocytic protozoan parasites of the genus Plasmodium. It remains an exigent public health problem in the tropical areas of Africa, South America and parts of Asia and continues to take its toll in morbidity and mortality with half of the world’s population under a permanent risk of infection leading to more than half a million deaths annually (WHO, 2013). Five Plasmodium species, namely P. falciparum (Pf ), P. vivax (Pv), P. ovale (Po), P. malariae (Pm) and P. knowlesi (Pk), are known to infect humans with Pf responsible for more than 90% of the malarial fatalities reported in sub-Saharan Africa. The predominance of Pf is attributed to its adaptability (Ashley, McGready, Proux, & Nosten, 2006; Prugnolle et al., 2011). Although the high occurrence of the Duffy negative trait among African populations lowers the threat posed by Pv, it is the most frequent and widely causative agent of benign tertian malaria in other parts of the world (Mendis, Sina, Marchesini, & Carter, 2001). In addition to the listed human malarial parasite forms, several other Plasmodium species, which infect non-human laboratory models, have been identified and are of significant importance in understanding the parasite biology, the host–parasite interactions and in the drug development process (Langhorne et al., 2011).
- Full Text:
- Date Issued: 2016
- Authors: Musyoka, Thommas M , Kanzi, Aquillah M , Lobb, Kevin A , Tastan Bishop, Özlem
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123074 , vital:35403 , https://doi.10.1080/07391102.2015.1108231
- Description: Malaria is an infectious disease caused by a diverse group of erythrocytic protozoan parasites of the genus Plasmodium. It remains an exigent public health problem in the tropical areas of Africa, South America and parts of Asia and continues to take its toll in morbidity and mortality with half of the world’s population under a permanent risk of infection leading to more than half a million deaths annually (WHO, 2013). Five Plasmodium species, namely P. falciparum (Pf ), P. vivax (Pv), P. ovale (Po), P. malariae (Pm) and P. knowlesi (Pk), are known to infect humans with Pf responsible for more than 90% of the malarial fatalities reported in sub-Saharan Africa. The predominance of Pf is attributed to its adaptability (Ashley, McGready, Proux, & Nosten, 2006; Prugnolle et al., 2011). Although the high occurrence of the Duffy negative trait among African populations lowers the threat posed by Pv, it is the most frequent and widely causative agent of benign tertian malaria in other parts of the world (Mendis, Sina, Marchesini, & Carter, 2001). In addition to the listed human malarial parasite forms, several other Plasmodium species, which infect non-human laboratory models, have been identified and are of significant importance in understanding the parasite biology, the host–parasite interactions and in the drug development process (Langhorne et al., 2011).
- Full Text:
- Date Issued: 2016
Anti-diabetic and phytochemical analysis of sutherlandia frutescens extracts
- Authors: Adefuye, Ogheneochuko Janet
- Date: 2016
- Subjects: Medicinal plants -- Africa , Traditional medicine -- Africa , Herbs -- Therapeutic use -- Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/3549 , vital:20441
- Description: In Africa, the importance of medicinal plants in folklore medicine and their contribution to primary healthcare is well recognized. Across the continent, local herbal mixtures still provide the only therapeutic option for about 80% of the population. The vast floral diversity and the intrinsic ethnobotanical knowledge has been the backbone of localized traditional herbal medical practices. In Africa, an estimated 5400 of the 60000 described plant taxa possess over 16300 therapeutic uses. Similarly, with a therapeutic flora comprising of approximately 650 species, herbal medical practitioners in South Africa, make use of a plethora of plants to treat different human diseases and infections. Over the years, studies have identified numerous plant species with potential against chronic metabolic diseases including type 2 diabetes mellitus (T2DM). Globally, the incidence and prevalence of T2DM have reached epidemic proportions affecting people of all ages, nationalities and ethnicity. Considered the fourth leading cause of deaths by disease, T2DM is a global health crisis with an estimated diagnosis and mortality frequency of 1 every 5 seconds and 1 every 7 seconds respectively. Though the exact pathophysiology of T2DM is not entirely understood, initial peripheral insulin resistance in adipose tissue, liver, and skeletal muscle with subsequent pancreatic β-cell dysfunction resulting from an attempt to compensate for insulin resistance is a common feature of the disease. The current approach to treating T2DM is the use of oral antidiabetic agents (OAAs), insulin, and incretin-based drugs in an attempt to achieve glycaemic control and maintain glucose homeostasis. However, conventional anti-T2DM drugs have been shown to have limited efficacies and serious adverse effects. Hence, the need for newer, more efficacious and safer anti-T2DM agents. Sutherlandia frutescens subsp. microphylla is a flowering shrub of the pea family (Fabaceae/Leguminaceae) found mainly in the Western Cape and Karoo regions of Southern Africa. Concoctions of various parts of the plant are used in the management of different ailments including T2DM. However, despite extensive biological and pharmacological studies, few analyses exist of the chemical constituents of S. frutescens and no Triple Time of Flight Liquid Chromatography with Mass Spectrometry (Triple TOF LC/MS/MS) analysis has been performed. The initial aim of this study was to investigate the phytochemical profile of hot aqueous, cold aqueous, 80% ethanolic, 100% ethanolic, 80% methanolic and 100% methanolic extracts of a single source S. frutescens plant material using colorimetric and spectrophotometric analysis. The hot aqueous extractant was found to be the best extractant for S. frutescens, yielding 1.99 g of crude extract from 16 g fresh powdered plant material. This data suggests that application of heat and water as the extractant (hot aqueous) could play a vital role in extraction of bioactive compounds from S. frutescens and also justifies the traditional use of a tea infusion of S. frutescens. Colorimetric analysis revealed the presence of flavonoids, flavonols, tannins, and phenols in all extracts with varying intensity. The organic extracts 100% methanol, 80% and 100% ethanol exhibited high color intensity (+++) for flavonoids and flavonols respectively, while all the extracts exhibited a moderate color intensity (++) for tannins and phenols. Spectrophotometric analysis of S. frutescens extracts revealed that all the organic extracts contained a significantly higher concentration (in mg/g of extract) of flavonols and tannins when compared to the aqueous extracts. All extracts contained approximately equal levels of phenols. These data confirm the presence of all four groups of bioactive phytocompounds in the S. frutescens extracts used in this study, and also confirm that different solvent extractants possess the capability to differentially extract specific groups of phytocompounds. in individual extracts. Further comparison of these compounds with online databases of anti-diabetic phytocompounds led to the preliminary identification of 10 possible anti-diabetic compounds; α-Pinene, Limonene, Sabinene, Carvone, Myricetin, Rutin, Stigmasterol, Emodin, Sarpagine and Hypoglycin B in crude and solid phase extraction (SPE) fractions of S. frutesecens. Furthermore, using two hepatic cell lines (Chang and HepG2) as an in-vtro model system, the anti-T2DM properties of crude aqueous and organic extracts of S. frutescents was investigated and compared. Both aqueous and organic extracts of S. frutescens were found to decrease gluconeogenesis, increase glucose uptake and decrease lipid accumulation (Triacylglycerol, Diacylglycerol, and Monoacylglycerol) in Chang and HepG2 hepatic cell cultures made insulin resistant (IR) following exposure to high concentration of insulin and fructose. Using real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), the aqueous and organic extracts of S. frutescens were confirmed to regulate the expression of Vesicle-associated membrane protein 3 (VAMP3), Mitogen-activated protein kinase 8 (MAPK8), and Insulin receptor substrate 1 (IRS1) in insulin resistant hepatic cells. IR-mediated downregulation of VAMP3, MAPK8, and IRS1 mRNA in IR HepG2 hepatic cell cultures was reversed in the presence of aqueous and organic extracts of S. frutescens. The hot aqueous extract displayed the highest activity in all the assays, while all the organic extracts displayed similar potency. In conclusion, this study reports that aqueous and organic extracts of S. frutescens possess numerous anti-diabetic compounds that can be further investigated for the development of new, more efficacious and less toxic anti-diabetic agents. The presence of multiple compounds in a single extract does suggest a synergistic or combinatorial therapeutic effect. These findings support the burgeoning body of in-vivo and in-vitro literature evidence on the anti-diabetic properties of S. frutescens and its use in folklore medicine.
- Full Text:
- Date Issued: 2016
- Authors: Adefuye, Ogheneochuko Janet
- Date: 2016
- Subjects: Medicinal plants -- Africa , Traditional medicine -- Africa , Herbs -- Therapeutic use -- Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/3549 , vital:20441
- Description: In Africa, the importance of medicinal plants in folklore medicine and their contribution to primary healthcare is well recognized. Across the continent, local herbal mixtures still provide the only therapeutic option for about 80% of the population. The vast floral diversity and the intrinsic ethnobotanical knowledge has been the backbone of localized traditional herbal medical practices. In Africa, an estimated 5400 of the 60000 described plant taxa possess over 16300 therapeutic uses. Similarly, with a therapeutic flora comprising of approximately 650 species, herbal medical practitioners in South Africa, make use of a plethora of plants to treat different human diseases and infections. Over the years, studies have identified numerous plant species with potential against chronic metabolic diseases including type 2 diabetes mellitus (T2DM). Globally, the incidence and prevalence of T2DM have reached epidemic proportions affecting people of all ages, nationalities and ethnicity. Considered the fourth leading cause of deaths by disease, T2DM is a global health crisis with an estimated diagnosis and mortality frequency of 1 every 5 seconds and 1 every 7 seconds respectively. Though the exact pathophysiology of T2DM is not entirely understood, initial peripheral insulin resistance in adipose tissue, liver, and skeletal muscle with subsequent pancreatic β-cell dysfunction resulting from an attempt to compensate for insulin resistance is a common feature of the disease. The current approach to treating T2DM is the use of oral antidiabetic agents (OAAs), insulin, and incretin-based drugs in an attempt to achieve glycaemic control and maintain glucose homeostasis. However, conventional anti-T2DM drugs have been shown to have limited efficacies and serious adverse effects. Hence, the need for newer, more efficacious and safer anti-T2DM agents. Sutherlandia frutescens subsp. microphylla is a flowering shrub of the pea family (Fabaceae/Leguminaceae) found mainly in the Western Cape and Karoo regions of Southern Africa. Concoctions of various parts of the plant are used in the management of different ailments including T2DM. However, despite extensive biological and pharmacological studies, few analyses exist of the chemical constituents of S. frutescens and no Triple Time of Flight Liquid Chromatography with Mass Spectrometry (Triple TOF LC/MS/MS) analysis has been performed. The initial aim of this study was to investigate the phytochemical profile of hot aqueous, cold aqueous, 80% ethanolic, 100% ethanolic, 80% methanolic and 100% methanolic extracts of a single source S. frutescens plant material using colorimetric and spectrophotometric analysis. The hot aqueous extractant was found to be the best extractant for S. frutescens, yielding 1.99 g of crude extract from 16 g fresh powdered plant material. This data suggests that application of heat and water as the extractant (hot aqueous) could play a vital role in extraction of bioactive compounds from S. frutescens and also justifies the traditional use of a tea infusion of S. frutescens. Colorimetric analysis revealed the presence of flavonoids, flavonols, tannins, and phenols in all extracts with varying intensity. The organic extracts 100% methanol, 80% and 100% ethanol exhibited high color intensity (+++) for flavonoids and flavonols respectively, while all the extracts exhibited a moderate color intensity (++) for tannins and phenols. Spectrophotometric analysis of S. frutescens extracts revealed that all the organic extracts contained a significantly higher concentration (in mg/g of extract) of flavonols and tannins when compared to the aqueous extracts. All extracts contained approximately equal levels of phenols. These data confirm the presence of all four groups of bioactive phytocompounds in the S. frutescens extracts used in this study, and also confirm that different solvent extractants possess the capability to differentially extract specific groups of phytocompounds. in individual extracts. Further comparison of these compounds with online databases of anti-diabetic phytocompounds led to the preliminary identification of 10 possible anti-diabetic compounds; α-Pinene, Limonene, Sabinene, Carvone, Myricetin, Rutin, Stigmasterol, Emodin, Sarpagine and Hypoglycin B in crude and solid phase extraction (SPE) fractions of S. frutesecens. Furthermore, using two hepatic cell lines (Chang and HepG2) as an in-vtro model system, the anti-T2DM properties of crude aqueous and organic extracts of S. frutescents was investigated and compared. Both aqueous and organic extracts of S. frutescens were found to decrease gluconeogenesis, increase glucose uptake and decrease lipid accumulation (Triacylglycerol, Diacylglycerol, and Monoacylglycerol) in Chang and HepG2 hepatic cell cultures made insulin resistant (IR) following exposure to high concentration of insulin and fructose. Using real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), the aqueous and organic extracts of S. frutescens were confirmed to regulate the expression of Vesicle-associated membrane protein 3 (VAMP3), Mitogen-activated protein kinase 8 (MAPK8), and Insulin receptor substrate 1 (IRS1) in insulin resistant hepatic cells. IR-mediated downregulation of VAMP3, MAPK8, and IRS1 mRNA in IR HepG2 hepatic cell cultures was reversed in the presence of aqueous and organic extracts of S. frutescens. The hot aqueous extract displayed the highest activity in all the assays, while all the organic extracts displayed similar potency. In conclusion, this study reports that aqueous and organic extracts of S. frutescens possess numerous anti-diabetic compounds that can be further investigated for the development of new, more efficacious and less toxic anti-diabetic agents. The presence of multiple compounds in a single extract does suggest a synergistic or combinatorial therapeutic effect. These findings support the burgeoning body of in-vivo and in-vitro literature evidence on the anti-diabetic properties of S. frutescens and its use in folklore medicine.
- Full Text:
- Date Issued: 2016
Antibacterial effects of Alchornea cordifolia (Schumach. and Thonn.) Müll. Arg extracts and compounds on gastrointestinal, skin, respiratory and urinary tract pathogens
- Siwe-Noundou, Xavier, Krause, Rui W M, van Vuuren, Sandy, Tantoh Ndinteh, Derek, Olivier, Denise K
- Authors: Siwe-Noundou, Xavier , Krause, Rui W M , van Vuuren, Sandy , Tantoh Ndinteh, Derek , Olivier, Denise K
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/195418 , vital:45563 , xlink:href="https://doi.org/10.1016/j.jep.2015.12.043"
- Description: Ethnopharmacological relevance:The leaves, stems and roots ofAlchornea cordifolia(Schumach. andThonn.) Müll. Arg. are used as traditional medicine in many African countries for the management ofgastrointestinal, respiratory and urinary tract infections as well as for the treatment of wounds.Aim of the study:To determine the in vitro antibacterial activity of the crude extracts of leaves and stemsofA. cordifoliaon gastrointestinal, skin, respiratory and urinary tract pathogens and to identify thecompounds in the extracts that may be responsible for this activity.Materials and methods:The antibacterial activities of crude extracts [hexane, chloroform (CHCl3), ethylacetate (EtOAc), ethanol (EtOH), methanol (MeOH) and water (H2O)] as well as pure compounds isolatedfrom these extracts were evaluated by means of the micro-dilution assay against four Gram-positivebacteria, i.e.Bacillus cereusATCC 11778,Enterococcus faecalisATCC 29212, Staphylococcus aureusATCC25923 andS. saprophyticusATCC 15305,as well as four Gram-negative bacterial strains, i.e.EscherichiacoliATCC 25922, Klebsiella pneumoniaeATCC 13883, Moraxella catarrhalisATCC 23246 andProteus mir-abilisATCC 43071. The isolation of the active constituents was undertaken by bio-autographic assays inconjunction with chromatographic techniques. The identification and characterisation of the isolatedcompounds were done using mass spectrometry (MS) and Fourier transformed infrared spectrometry(FTIR) as well as 1D- and 2D- nuclear magnetic resonance (NMR) analyses.Results:The leaves and stems ofA. cordifoliaexhibited varied antibacterial activity against all eight pa-thogens. Most of the MIC values ranged between 63 and 2000mg/ml. The highest activities for the crudeextracts (63mg/ml) were observed againstS. saprophyticus[stem (EtOAc, CHCl3and hexane), leaves(MeOH, EtOH, EtOAc and CHCl3)],E. coli[stem (MeOH and EtOH), leaves (MeOH, EtOH, EtOAc andCHCl3)],M. catarrhalis[leaves (EtOAc and CHCl3)],K. pneumoniae[stem (CHCl3), leaves (CHCl3)] andS.aureus[leaves (CHCl3)]. Seven constituents [stigmasterol (1), stigmasta-4,22-dien-3-one (2), friedelin (3),friedelane-3-one-28-al (4), 3-O-acetyl-aleuritolic acid (5), 3-O-acetyl-erythrodiol (6) and methyl-3,4,5-trihydroxybenzoate (methyl gallate) (7)] were isolated from the stem MeOH extract. All these com-pounds displayed some antibacterial activity against the eight pathogens with highest activity againstS.saprophyticus(2mg/ml). Furthermore, this is thefirst report of compounds1,2,3,4,6and7isolated fromA. cordifoliaand where a complete set of 2D-NMR data for fridelane-3-one-28-al (4) is presented.Conclusion:The study demonstrated that the antibacterial activities ofA. cordifoliaextracts may be dueto the presence of the seven isolated compounds, where compounds3–6showed the best activity. Theobserved activity against gastrointestinal, skin, respiratory and urinary tract pathogens supports thetraditional use for the treatment of such ailments.
- Full Text:
- Date Issued: 2016
- Authors: Siwe-Noundou, Xavier , Krause, Rui W M , van Vuuren, Sandy , Tantoh Ndinteh, Derek , Olivier, Denise K
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/195418 , vital:45563 , xlink:href="https://doi.org/10.1016/j.jep.2015.12.043"
- Description: Ethnopharmacological relevance:The leaves, stems and roots ofAlchornea cordifolia(Schumach. andThonn.) Müll. Arg. are used as traditional medicine in many African countries for the management ofgastrointestinal, respiratory and urinary tract infections as well as for the treatment of wounds.Aim of the study:To determine the in vitro antibacterial activity of the crude extracts of leaves and stemsofA. cordifoliaon gastrointestinal, skin, respiratory and urinary tract pathogens and to identify thecompounds in the extracts that may be responsible for this activity.Materials and methods:The antibacterial activities of crude extracts [hexane, chloroform (CHCl3), ethylacetate (EtOAc), ethanol (EtOH), methanol (MeOH) and water (H2O)] as well as pure compounds isolatedfrom these extracts were evaluated by means of the micro-dilution assay against four Gram-positivebacteria, i.e.Bacillus cereusATCC 11778,Enterococcus faecalisATCC 29212, Staphylococcus aureusATCC25923 andS. saprophyticusATCC 15305,as well as four Gram-negative bacterial strains, i.e.EscherichiacoliATCC 25922, Klebsiella pneumoniaeATCC 13883, Moraxella catarrhalisATCC 23246 andProteus mir-abilisATCC 43071. The isolation of the active constituents was undertaken by bio-autographic assays inconjunction with chromatographic techniques. The identification and characterisation of the isolatedcompounds were done using mass spectrometry (MS) and Fourier transformed infrared spectrometry(FTIR) as well as 1D- and 2D- nuclear magnetic resonance (NMR) analyses.Results:The leaves and stems ofA. cordifoliaexhibited varied antibacterial activity against all eight pa-thogens. Most of the MIC values ranged between 63 and 2000mg/ml. The highest activities for the crudeextracts (63mg/ml) were observed againstS. saprophyticus[stem (EtOAc, CHCl3and hexane), leaves(MeOH, EtOH, EtOAc and CHCl3)],E. coli[stem (MeOH and EtOH), leaves (MeOH, EtOH, EtOAc andCHCl3)],M. catarrhalis[leaves (EtOAc and CHCl3)],K. pneumoniae[stem (CHCl3), leaves (CHCl3)] andS.aureus[leaves (CHCl3)]. Seven constituents [stigmasterol (1), stigmasta-4,22-dien-3-one (2), friedelin (3),friedelane-3-one-28-al (4), 3-O-acetyl-aleuritolic acid (5), 3-O-acetyl-erythrodiol (6) and methyl-3,4,5-trihydroxybenzoate (methyl gallate) (7)] were isolated from the stem MeOH extract. All these com-pounds displayed some antibacterial activity against the eight pathogens with highest activity againstS.saprophyticus(2mg/ml). Furthermore, this is thefirst report of compounds1,2,3,4,6and7isolated fromA. cordifoliaand where a complete set of 2D-NMR data for fridelane-3-one-28-al (4) is presented.Conclusion:The study demonstrated that the antibacterial activities ofA. cordifoliaextracts may be dueto the presence of the seven isolated compounds, where compounds3–6showed the best activity. Theobserved activity against gastrointestinal, skin, respiratory and urinary tract pathogens supports thetraditional use for the treatment of such ailments.
- Full Text:
- Date Issued: 2016
Application of Baylis-Hillman methodology in the direct construction of chromone derivatives
- Faridoon, H, Olomola, Temitope O, Klein, Rosalyn, Kaye, Perry T
- Authors: Faridoon, H , Olomola, Temitope O , Klein, Rosalyn , Kaye, Perry T
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442488 , vital:73992 , https://doi.org/10.1016/j.tet.2015.11.039
- Description: Pyridinium chlorochromate oxidation of Baylis-Hillman-derived tert-butyl 2H-chromene-3-carboxylates affords chromone-3-carboxylate esters, providing the first application of Baylis-Hillman methodology in a direct and convenient three-step synthesis of chromone derivatives.
- Full Text:
- Date Issued: 2016
- Authors: Faridoon, H , Olomola, Temitope O , Klein, Rosalyn , Kaye, Perry T
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442488 , vital:73992 , https://doi.org/10.1016/j.tet.2015.11.039
- Description: Pyridinium chlorochromate oxidation of Baylis-Hillman-derived tert-butyl 2H-chromene-3-carboxylates affords chromone-3-carboxylate esters, providing the first application of Baylis-Hillman methodology in a direct and convenient three-step synthesis of chromone derivatives.
- Full Text:
- Date Issued: 2016