Day-of-the-week effect : evidence from nine sectors of the South African stock market
- Authors: Mbululu, Douglas
- Date: 2010
- Subjects: Stock exchanges -- South Africa , Johannesburg Stock Exchange , Stocks -- Prices -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1024 , http://hdl.handle.net/10962/d1002759 , Stock exchanges -- South Africa , Johannesburg Stock Exchange , Stocks -- Prices -- South Africa
- Description: The day-of-the-week effect in share prices is one of the most extensively researched anomalies, especially in developed markets. However, emerging African stock markets have received little attention in this regard. This study breaks new ground in using non-parametric tests directly on skewness and kurtosis to examine whether the day-of-he-week effect exists in nine listed stock market sector indices of the JSE Securities Exchange of South Africa (JSE). Different day-of-the-week effects were found to be present in the statistical moments of returns of these nine JSE sectors
- Full Text:
- Authors: Mbululu, Douglas
- Date: 2010
- Subjects: Stock exchanges -- South Africa , Johannesburg Stock Exchange , Stocks -- Prices -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1024 , http://hdl.handle.net/10962/d1002759 , Stock exchanges -- South Africa , Johannesburg Stock Exchange , Stocks -- Prices -- South Africa
- Description: The day-of-the-week effect in share prices is one of the most extensively researched anomalies, especially in developed markets. However, emerging African stock markets have received little attention in this regard. This study breaks new ground in using non-parametric tests directly on skewness and kurtosis to examine whether the day-of-he-week effect exists in nine listed stock market sector indices of the JSE Securities Exchange of South Africa (JSE). Different day-of-the-week effects were found to be present in the statistical moments of returns of these nine JSE sectors
- Full Text:
Deliberating the Dialogues: a critical examination of the nature and purpose of a Daily Dispatch public journalism project
- Authors: Amner, Roderick John
- Date: 2010
- Subjects: Daily Dispatch (East London, South Africa) Journalism -- South Africa -- East London Citizen journalism -- South Africa -- East London
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3417 , http://hdl.handle.net/10962/d1002870
- Description: This thesis critically examines the nature and purpose of a series of four town-hall-like meetings, the Community Dialogues, held in the townships and suburbs of East London, South Africa, in 2009. They were undertaken by a mainstream, commercial newspaper, the Daily Dispatch, under the banner of the worldwide public journalism movement. Following Christians et al (2009), the thesis sets out a normative framework of media performance in a democracy, including a detailed and critical normative theory of the ‘facilitative role’ proposed and developed by Haas (2007), one of the public journalism movement’s key advocate-theorists. It also draws on a variety of theoretical frameworks and perspectives in the fields of Political Studies and Media Studies to provide an analytical overview of the complex matrix of political and media contexts – at the macro (global), meso (national) and micro (local) levels – that have helped give impetus to the Community Dialogues and also shaped their ongoing operation as a public journalism strategy in the South African context. Following a critical realist case study design, the thesis goes on to provide a narrative account of the Dialogues based on in-depth interviews exploring the motivations, self-understandings and perceptions of those journalists who originated, directed and participated in this project, as well as observation of a Community Dialogue, and an examination of some of the journalistic texts related to the Dialogues. This primary data is then critically evaluated against normative theories of press performance, especially Haas’s ‘public philosophy’ of public journalism. The thesis found that apart from their undoubted success in generating a more comprehensive and representative news agenda for the newspaper, the Dialogues often fell short of Habermas’s (1989) proceduralist-discursive notion of the ‘deliberating public’, which sees citizens share a commitment to engage in common deliberation and public problem solving. This can be attributed to a number of problems, including some important theoretical/conceptual weaknesses in the Community Dialogues’ project design, the relative immaturity of the project, the domination of civil society by political society in the South African political context, and a number of organisational constraints at the Daily Dispatch. On the other hand, the newspaper’s editorial leadership has shown clear commitment to the idea of expanding the project in the future, establishing a more a more structured programme of community engagement, and nurturing a more sustainable public sphere, including the building of a more dialectical relationship between the Dialogues and civil society.
- Full Text:
- Authors: Amner, Roderick John
- Date: 2010
- Subjects: Daily Dispatch (East London, South Africa) Journalism -- South Africa -- East London Citizen journalism -- South Africa -- East London
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3417 , http://hdl.handle.net/10962/d1002870
- Description: This thesis critically examines the nature and purpose of a series of four town-hall-like meetings, the Community Dialogues, held in the townships and suburbs of East London, South Africa, in 2009. They were undertaken by a mainstream, commercial newspaper, the Daily Dispatch, under the banner of the worldwide public journalism movement. Following Christians et al (2009), the thesis sets out a normative framework of media performance in a democracy, including a detailed and critical normative theory of the ‘facilitative role’ proposed and developed by Haas (2007), one of the public journalism movement’s key advocate-theorists. It also draws on a variety of theoretical frameworks and perspectives in the fields of Political Studies and Media Studies to provide an analytical overview of the complex matrix of political and media contexts – at the macro (global), meso (national) and micro (local) levels – that have helped give impetus to the Community Dialogues and also shaped their ongoing operation as a public journalism strategy in the South African context. Following a critical realist case study design, the thesis goes on to provide a narrative account of the Dialogues based on in-depth interviews exploring the motivations, self-understandings and perceptions of those journalists who originated, directed and participated in this project, as well as observation of a Community Dialogue, and an examination of some of the journalistic texts related to the Dialogues. This primary data is then critically evaluated against normative theories of press performance, especially Haas’s ‘public philosophy’ of public journalism. The thesis found that apart from their undoubted success in generating a more comprehensive and representative news agenda for the newspaper, the Dialogues often fell short of Habermas’s (1989) proceduralist-discursive notion of the ‘deliberating public’, which sees citizens share a commitment to engage in common deliberation and public problem solving. This can be attributed to a number of problems, including some important theoretical/conceptual weaknesses in the Community Dialogues’ project design, the relative immaturity of the project, the domination of civil society by political society in the South African political context, and a number of organisational constraints at the Daily Dispatch. On the other hand, the newspaper’s editorial leadership has shown clear commitment to the idea of expanding the project in the future, establishing a more a more structured programme of community engagement, and nurturing a more sustainable public sphere, including the building of a more dialectical relationship between the Dialogues and civil society.
- Full Text:
Democratic leadership and management practices in a rural Namibian secondary school
- Authors: Mabuku, Robert Nalisa
- Date: 2010
- Subjects: Educational leadership -- Namibia -- Case studies School management and organization -- Namibia -- Case studies Education, Secondary -- Namibia -- Case studies Educational change -- Namibia -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1489 , http://hdl.handle.net/10962/d1003370
- Description: The primary purpose of this research was to investigate the understanding and implementation of democratic leadership and management in schools by school managers and other members of the school community in leadership and management roles as advocated by the policy of Education for all. The study also aimed at identifying any gaps in the understanding and practice of the participants in order to enhance democratic leadership and management in schools. Qualitative research using the interpretive approach was the methodology employed in order to fulfill the intention of the study, namely to investigate the participants` experiences and understanding of democratic education leadership and management. The case study method was appropriate to understand the meanings the participants attached to their practice in their natural setting. Data were collected by using semi-structured interviews, document analysis, and observation. The sample for the study consisted of ten participants: the principal, the head of department, two School Board members, two senior teachers, two Learner Representative Council members and two class captains. The findings suggest that the participants understood and practised democratic ELM in terms of broader participation, open communication, delegation for empowerment, learning organisation, shared decision-making, shared leadership and teamwork. However, the data suggest areas of concern in the participants` understanding and implementation of the policy which could be strengthened to entrench the policy. The study recommends that education policy makers, education managers, school managers, teachers, parents and learners all work towards improving democratic ELM in schools. In order to achieve this objective, policy makers are urged to avoid ambiguity to enable all implementers to fully understand policies. Education managers could ensure school-wide training on the policy while school managers and other stakeholders should engage in self-reflection and introspection and be more proactive towards improving their own understanding and practice.
- Full Text:
- Authors: Mabuku, Robert Nalisa
- Date: 2010
- Subjects: Educational leadership -- Namibia -- Case studies School management and organization -- Namibia -- Case studies Education, Secondary -- Namibia -- Case studies Educational change -- Namibia -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1489 , http://hdl.handle.net/10962/d1003370
- Description: The primary purpose of this research was to investigate the understanding and implementation of democratic leadership and management in schools by school managers and other members of the school community in leadership and management roles as advocated by the policy of Education for all. The study also aimed at identifying any gaps in the understanding and practice of the participants in order to enhance democratic leadership and management in schools. Qualitative research using the interpretive approach was the methodology employed in order to fulfill the intention of the study, namely to investigate the participants` experiences and understanding of democratic education leadership and management. The case study method was appropriate to understand the meanings the participants attached to their practice in their natural setting. Data were collected by using semi-structured interviews, document analysis, and observation. The sample for the study consisted of ten participants: the principal, the head of department, two School Board members, two senior teachers, two Learner Representative Council members and two class captains. The findings suggest that the participants understood and practised democratic ELM in terms of broader participation, open communication, delegation for empowerment, learning organisation, shared decision-making, shared leadership and teamwork. However, the data suggest areas of concern in the participants` understanding and implementation of the policy which could be strengthened to entrench the policy. The study recommends that education policy makers, education managers, school managers, teachers, parents and learners all work towards improving democratic ELM in schools. In order to achieve this objective, policy makers are urged to avoid ambiguity to enable all implementers to fully understand policies. Education managers could ensure school-wide training on the policy while school managers and other stakeholders should engage in self-reflection and introspection and be more proactive towards improving their own understanding and practice.
- Full Text:
Demographical diversity influence on online shopping orientation and propensity to buy online
- Authors: Tapson, Megan Jacqueline
- Date: 2010
- Subjects: Teleshopping -- South Africa , Electronic commerce -- South Africa , Consumer behavior -- South Africa -- Cross-cultural studies , Ethnicity -- South Africa , Ethnic attitudes -- South Africa , Consumer behavior -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:1168 , http://hdl.handle.net/10962/d1002784 , Teleshopping -- South Africa , Electronic commerce -- South Africa , Consumer behavior -- South Africa -- Cross-cultural studies , Ethnicity -- South Africa , Ethnic attitudes -- South Africa , Consumer behavior -- South Africa
- Description: Online shopping is a growing phenomenon all over the world, and it has thus had an influence on the shopping process for many consumers (Brengman et al., 2005:79; Brown et al., 2003:1667; Kau et al., 2003:139). Consumers are now choosing to shop online due to changes in their lifestyles and demographic diversity (Kau et al., 2003:139). The purpose of this research was to examine the extent to which demographic diversity influenced online shopping orientation and propensity to buy online. The researcher first conducted an in-depth theoretical study of previous research into demographic diversity, online shopping orientation and propensity to buy online. Next, the researcher conducted an empirical survey questionnaire, in order to assess the opinions of students at the three selected Eastern Cape universities. Phinney's (1992:156) multi-group ethnic identity measure was administered in order to identify how respondents feel about their ethnicity and/or how they react to their own ethnic group. Kau et al.,'s (2003) online shopping orientation measure was used to help identify six relevant online shopping factors. The six online shopping factors where then used to describe six online shopping orientation types. The main findings of this research conducted at three Universities in the Eastern Cape can be summarised as follows: Ethnic Identity Profile: - Within this research it was found that respondents at all three universities in general had a strong ethnic identity to their specified ethnic group, according to the two ethnic identity factors namely; commitment and exploration. Online Shopping Orientation Profile: - Within this research it was found that the respondents at all three universities in general could be categorised in one of six online shopping orientation types according to six online shopping factors. The extent to which demographic diversity influences types of online shopping orientation: - From the research hypotheses it was concluded that a relationship exists between demographic diversity and types of online shopping orientations, whereby the gender, race and ethnicity of respondent is likely to influence the way consumers shop online, namely the consumers‟ online shopping orientation. The extent to which demographic diversity influences propensity to buy online: - From the research hypotheses it was concluded that a relationship exists between demographic diversity and propensity to buy online, whereby the gender of respondents is likely to influence whether consumers buy online in the future. - From the research hypotheses it was concluded that no relationship exists between demographic diversity and propensity to buy online, whereby the race and ethnicity of respondents is not likely to influence whether consumers buy online in the future. The extent to which types of online shopping orientation influence propensity to buy online: - The findings suggest that different online shopping orientations have different propensities to buy online in the future. Hence, marketers should be aware of the online shopping orientations more likely to buy online in the future and focus their marketing programs on them. They should also try new ways to attract the online shopping orientations that may not buy online, in the hopes of changing their opinions and perceptions of the Internet and online shopping. South Africa, in particular, consists of multi-racial and diverse ethnic origins, which has resulted in a demographically diverse South African nation. Therefore, marketers need to develop a better understanding of consumers‟ online shopping orientation (Donthu and Garcia, 1999:57; Jayawardhena and Foley, 2000:19; Kau et al., 2003:140). Understanding consumers' online shopping orientation will assist marketers in being able to market to specific consumers and meet the needs of consumers effectively (Kau et al., 2003:140). Since demographic diversity influences the online shopping orientations of consumers, major opportunities for marketers will be provided by accommodating for a demographically diverse South African nation.
- Full Text:
- Authors: Tapson, Megan Jacqueline
- Date: 2010
- Subjects: Teleshopping -- South Africa , Electronic commerce -- South Africa , Consumer behavior -- South Africa -- Cross-cultural studies , Ethnicity -- South Africa , Ethnic attitudes -- South Africa , Consumer behavior -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:1168 , http://hdl.handle.net/10962/d1002784 , Teleshopping -- South Africa , Electronic commerce -- South Africa , Consumer behavior -- South Africa -- Cross-cultural studies , Ethnicity -- South Africa , Ethnic attitudes -- South Africa , Consumer behavior -- South Africa
- Description: Online shopping is a growing phenomenon all over the world, and it has thus had an influence on the shopping process for many consumers (Brengman et al., 2005:79; Brown et al., 2003:1667; Kau et al., 2003:139). Consumers are now choosing to shop online due to changes in their lifestyles and demographic diversity (Kau et al., 2003:139). The purpose of this research was to examine the extent to which demographic diversity influenced online shopping orientation and propensity to buy online. The researcher first conducted an in-depth theoretical study of previous research into demographic diversity, online shopping orientation and propensity to buy online. Next, the researcher conducted an empirical survey questionnaire, in order to assess the opinions of students at the three selected Eastern Cape universities. Phinney's (1992:156) multi-group ethnic identity measure was administered in order to identify how respondents feel about their ethnicity and/or how they react to their own ethnic group. Kau et al.,'s (2003) online shopping orientation measure was used to help identify six relevant online shopping factors. The six online shopping factors where then used to describe six online shopping orientation types. The main findings of this research conducted at three Universities in the Eastern Cape can be summarised as follows: Ethnic Identity Profile: - Within this research it was found that respondents at all three universities in general had a strong ethnic identity to their specified ethnic group, according to the two ethnic identity factors namely; commitment and exploration. Online Shopping Orientation Profile: - Within this research it was found that the respondents at all three universities in general could be categorised in one of six online shopping orientation types according to six online shopping factors. The extent to which demographic diversity influences types of online shopping orientation: - From the research hypotheses it was concluded that a relationship exists between demographic diversity and types of online shopping orientations, whereby the gender, race and ethnicity of respondent is likely to influence the way consumers shop online, namely the consumers‟ online shopping orientation. The extent to which demographic diversity influences propensity to buy online: - From the research hypotheses it was concluded that a relationship exists between demographic diversity and propensity to buy online, whereby the gender of respondents is likely to influence whether consumers buy online in the future. - From the research hypotheses it was concluded that no relationship exists between demographic diversity and propensity to buy online, whereby the race and ethnicity of respondents is not likely to influence whether consumers buy online in the future. The extent to which types of online shopping orientation influence propensity to buy online: - The findings suggest that different online shopping orientations have different propensities to buy online in the future. Hence, marketers should be aware of the online shopping orientations more likely to buy online in the future and focus their marketing programs on them. They should also try new ways to attract the online shopping orientations that may not buy online, in the hopes of changing their opinions and perceptions of the Internet and online shopping. South Africa, in particular, consists of multi-racial and diverse ethnic origins, which has resulted in a demographically diverse South African nation. Therefore, marketers need to develop a better understanding of consumers‟ online shopping orientation (Donthu and Garcia, 1999:57; Jayawardhena and Foley, 2000:19; Kau et al., 2003:140). Understanding consumers' online shopping orientation will assist marketers in being able to market to specific consumers and meet the needs of consumers effectively (Kau et al., 2003:140). Since demographic diversity influences the online shopping orientations of consumers, major opportunities for marketers will be provided by accommodating for a demographically diverse South African nation.
- Full Text:
Desktop control for a host apparatus of a digital multimedia network
- Gurdan, Robby, Foss, Richard
- Authors: Gurdan, Robby , Foss, Richard
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427070 , vital:72412 , https://patentimages.storage.googleapis.com/f6/97/d3/a66cc5c9e77021/US20100287491A1.pdf
- Description: The invention provides a desktop control and a browser for a host apparatus of a digital multimedia network. The desktop control comprises a processing core having at least one desk parameter link (DPL) to a device parameter of the host apparatus. Furthermore, the processing core can have at least one desk application link (DAL) to a browser application of the host apparatus. The processing core further has one or more desk item links to other desktop controls of another apparatus within the digital multimedia network.
- Full Text:
- Authors: Gurdan, Robby , Foss, Richard
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427070 , vital:72412 , https://patentimages.storage.googleapis.com/f6/97/d3/a66cc5c9e77021/US20100287491A1.pdf
- Description: The invention provides a desktop control and a browser for a host apparatus of a digital multimedia network. The desktop control comprises a processing core having at least one desk parameter link (DPL) to a device parameter of the host apparatus. Furthermore, the processing core can have at least one desk application link (DAL) to a browser application of the host apparatus. The processing core further has one or more desk item links to other desktop controls of another apparatus within the digital multimedia network.
- Full Text:
Determining spatial changes in the diet of nearshore suspension-feeders along the South African coastline: stable isotope and fatty acid signatures
- Allan, E Louise, Ambrose, Shan T, Richoux, Nicole B, Froneman, P William
- Authors: Allan, E Louise , Ambrose, Shan T , Richoux, Nicole B , Froneman, P William
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457945 , vital:75697 , xlink:href="https://doi.org/10.1016/j.ecss.2010.02.004"
- Description: Mesoscale oceanographic features, such as upwellings, are known to play an important role in regulating the structure and productivity of nearshore marine communities. Stable isotope (δ13C and δ15N) and fatty acid analyses were employed to assess the influence of an upwelling cell along the south-eastern coastline of southern Africa on the diet of the mussel, Perna perna. Eight sites were sampled: two upstream, three in the vicinity and three downstream of the upwelling cell. Stable isotope and fatty acid signatures indicated that the mussels consumed a diet of detritus derived mainly from macroalgae, diatoms and dinoflagellates. One-way ANOVA on the δ13C and δ15N signatures and the principal component analysis of the fatty acid profiles of the mussels identified distinct groups corresponding to the above mentioned regions. The proportion of diatom biomarkers in the fatty acid profiles decreased downstream of the upwelling region while the proportion of dinoflagellate biomarkers increased. Upwelling regions are typically associated with elevated levels of productivity; however, these systems usually become silicon depleted and result in the replacement of diatoms with dinoflagellates. The highest proportions of the dinoflagellate markers were recorded in the two furthest sites downstream of the upwelling cell. The spatial variation in the diet of the mussels, therefore, appears to reflect the presence of the upwelling cell in the nearshore biology of the region.
- Full Text:
- Authors: Allan, E Louise , Ambrose, Shan T , Richoux, Nicole B , Froneman, P William
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/457945 , vital:75697 , xlink:href="https://doi.org/10.1016/j.ecss.2010.02.004"
- Description: Mesoscale oceanographic features, such as upwellings, are known to play an important role in regulating the structure and productivity of nearshore marine communities. Stable isotope (δ13C and δ15N) and fatty acid analyses were employed to assess the influence of an upwelling cell along the south-eastern coastline of southern Africa on the diet of the mussel, Perna perna. Eight sites were sampled: two upstream, three in the vicinity and three downstream of the upwelling cell. Stable isotope and fatty acid signatures indicated that the mussels consumed a diet of detritus derived mainly from macroalgae, diatoms and dinoflagellates. One-way ANOVA on the δ13C and δ15N signatures and the principal component analysis of the fatty acid profiles of the mussels identified distinct groups corresponding to the above mentioned regions. The proportion of diatom biomarkers in the fatty acid profiles decreased downstream of the upwelling region while the proportion of dinoflagellate biomarkers increased. Upwelling regions are typically associated with elevated levels of productivity; however, these systems usually become silicon depleted and result in the replacement of diatoms with dinoflagellates. The highest proportions of the dinoflagellate markers were recorded in the two furthest sites downstream of the upwelling cell. The spatial variation in the diet of the mussels, therefore, appears to reflect the presence of the upwelling cell in the nearshore biology of the region.
- Full Text:
Developing a systematic model for the capturing and use of African oral poetry: the Bongani Sitole experience
- Authors: Mostert, André M
- Date: 2010
- Subjects: Sitole, Bongani, 1937- Communication and culture Oral tradition in literature Oral tradition -- Africa Ethnoscience -- Africa Folk poetry, African
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3579 , http://hdl.handle.net/10962/d1002154
- Description: Oral traditions and oral literature have long contributed to human communication. The advent of arguably the most important technology, the written word, altered human ability to create and develop. However, this development for all its potential and scope created one of the most insidious dichotomies. As the written word developed so too the oral word became devalued and pushed to the fringes of societal development. One of the unfortunate outcomes has been a focus on the nomenclatures associated with orality and oral tradition, which although of importance, has skewed where the focus could and should have been located, namely, how to support and maintain the oral word and its innate value to human society in the face of what has become rampant technological developments. It is now ironic that technology is creating a fecund environment for a rebirth of orality. The study aims to mobilize technauriture as a paradigm in order to further embed orality and oral traditions to coherently embrace this changing technological environment. The central tenet of the study is that in order to enhance the status of orality the innate value embodied in indigenous knowledge systems must be recognized. Using the work of Bongani Sitole, an oral poet, as a backdrop the study will demonstrate a basic model that can act as a foundation for the effective integration of orality into contemporary structures. This is based on work that I published in the Journal of African Contemporary Studies (2009). Given the obvious multi-disciplinary nature of the material the work covers a wide cross section of the debate, from questions of epistemology and knowledge in general in terms of oral traditions, through the consciousness and technical landscapes, via the experience with Sitole’s material to issues of copyright and ownership. This work has also been submitted for publication together with my supervisor as a co-author. The study intends to consolidate the technauriture debate and lay a solid foundation to support further study.
- Full Text:
- Authors: Mostert, André M
- Date: 2010
- Subjects: Sitole, Bongani, 1937- Communication and culture Oral tradition in literature Oral tradition -- Africa Ethnoscience -- Africa Folk poetry, African
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3579 , http://hdl.handle.net/10962/d1002154
- Description: Oral traditions and oral literature have long contributed to human communication. The advent of arguably the most important technology, the written word, altered human ability to create and develop. However, this development for all its potential and scope created one of the most insidious dichotomies. As the written word developed so too the oral word became devalued and pushed to the fringes of societal development. One of the unfortunate outcomes has been a focus on the nomenclatures associated with orality and oral tradition, which although of importance, has skewed where the focus could and should have been located, namely, how to support and maintain the oral word and its innate value to human society in the face of what has become rampant technological developments. It is now ironic that technology is creating a fecund environment for a rebirth of orality. The study aims to mobilize technauriture as a paradigm in order to further embed orality and oral traditions to coherently embrace this changing technological environment. The central tenet of the study is that in order to enhance the status of orality the innate value embodied in indigenous knowledge systems must be recognized. Using the work of Bongani Sitole, an oral poet, as a backdrop the study will demonstrate a basic model that can act as a foundation for the effective integration of orality into contemporary structures. This is based on work that I published in the Journal of African Contemporary Studies (2009). Given the obvious multi-disciplinary nature of the material the work covers a wide cross section of the debate, from questions of epistemology and knowledge in general in terms of oral traditions, through the consciousness and technical landscapes, via the experience with Sitole’s material to issues of copyright and ownership. This work has also been submitted for publication together with my supervisor as a co-author. The study intends to consolidate the technauriture debate and lay a solid foundation to support further study.
- Full Text:
Developing an ionospheric map for South Africa
- McKinnell, Lee-Anne, Okoh, D I, Cilliers, P J
- Authors: McKinnell, Lee-Anne , Okoh, D I , Cilliers, P J
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6822 , http://hdl.handle.net/10962/d1004438 , http://dx.doi.org/10.5194/angeo-28-1431-2010
- Description: The development of a map of the ionosphere over South Africa is presented in this paper. The International Reference Ionosphere (IRI) model, South African Bottomside Ionospheric Model (SABIM), and measurements from ionosondes in the South African Ionosonde Network, were combined within their own limitations to develop an accurate representation of the South African ionosphere. The map is essentially in the form of a computer program that shows spatial and temporal representations of the South African ionosphere for a given set of geophysical parameters. A validation of the map is attempted using a comparison of Total Electron Content (TEC) values derived from the map, from the IRI model, and from Global Positioning System (GPS) measurements. It is foreseen that the final South African ionospheric map will be implemented as a Space Weather product of the African Space Weather Regional Warning Centre.
- Full Text:
- Authors: McKinnell, Lee-Anne , Okoh, D I , Cilliers, P J
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6822 , http://hdl.handle.net/10962/d1004438 , http://dx.doi.org/10.5194/angeo-28-1431-2010
- Description: The development of a map of the ionosphere over South Africa is presented in this paper. The International Reference Ionosphere (IRI) model, South African Bottomside Ionospheric Model (SABIM), and measurements from ionosondes in the South African Ionosonde Network, were combined within their own limitations to develop an accurate representation of the South African ionosphere. The map is essentially in the form of a computer program that shows spatial and temporal representations of the South African ionosphere for a given set of geophysical parameters. A validation of the map is attempted using a comparison of Total Electron Content (TEC) values derived from the map, from the IRI model, and from Global Positioning System (GPS) measurements. It is foreseen that the final South African ionospheric map will be implemented as a Space Weather product of the African Space Weather Regional Warning Centre.
- Full Text:
Development and assessment of minocycline sustained release capsule formulations
- Sachikonye, Tinotenda Chipo Victoria
- Authors: Sachikonye, Tinotenda Chipo Victoria
- Date: 2010
- Subjects: Drugs -- Controlled release , Drugs -- Dosage forms , Capsules (Pharmacy) , Drugs -- Administration , Acne -- Treatment , Tetracyclines , Antibiotics -- Side effects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3854 , http://hdl.handle.net/10962/d1013127
- Description: The use of minocycline for the treatment of a broad range of systemic infections and for severe acne has been associated with vestibular side effects. The severity of side effects may lead to poor adherence to therapy by patients. The use of sustained release formulations of minocycline that display slow dissolution of minocycline following administration may be beneficial in reducing the incidence and severity of side effects. Therefore, sustained release capsule dosage forms containing 100 mg minocycline (base) were manufactured and assessed for use as sustained release oral dosage forms of minocycline. Minocycline sustained release capsules were manufactured based on matrix technologies using hydroxypropylmethyl cellulose (HPMC) and Compritol® as release retarding polymers. The rate and extent of minocycline release from the capsules was evaluated using USP Apparatus 1 and samples were analysed using a validated High Performance Liquid Chromatographic (HPLC) method with ultraviolet (UV) detection. Differences in the rate and extent of minocycline release from formulations manufactured using HPMC or Compritol® were influenced by the concentration of polymer used in the formulations. The rate and extent of minocycline release was faster and greater when low concentrations of polymer were used in formulations. The effect of different excipients on the release pattern(s) of minocycline and particularly their potential to optimise minocycline release from experimental formulations was investigated. The use of diluents such as lactose and microcrystalline cellulose (MCC) revealed that lactose facilitated minocycline release when HPMC was used as the polymer matrix. In contrast, the use of lactose as diluent resulted in slower release of minocycline from Compritol® based formulations. The addition of sodium starch glycolate to HPMC based formulations resulted in slower release of minocycline than when no sodium starch glycolate was used. Compritol® based formulations were observed to release minocycline faster following addition of sodium starch glycolate and Poloxamer 188 to experimental formulations. In vitro dissolution profiles were compared to a target or reference profile using the difference and similarity factors, ƒ1 and ƒ2 , and a one way analysis of variance (ANOVA). In addition, the mechanism of minocycline release was elucidated following fitting of dissolution data to the Korsmeyer-Peppas, Higuchi and Zero order models. Minocycline release kinetics were best described by the Korsmeyer-Peppas model and the values of the release exponent, n (italics), revealed that drug release was a result of the combined effects of minocycline diffusion through matrices and erosion of the matrices. These in vitro dissolution profiles were better fit to the Higuchi model than to the Zero order model. Two formulations that displayed a fit to the Zero order model were identified for further studies as potential dosage forms for sustained release minocycline.
- Full Text:
- Authors: Sachikonye, Tinotenda Chipo Victoria
- Date: 2010
- Subjects: Drugs -- Controlled release , Drugs -- Dosage forms , Capsules (Pharmacy) , Drugs -- Administration , Acne -- Treatment , Tetracyclines , Antibiotics -- Side effects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3854 , http://hdl.handle.net/10962/d1013127
- Description: The use of minocycline for the treatment of a broad range of systemic infections and for severe acne has been associated with vestibular side effects. The severity of side effects may lead to poor adherence to therapy by patients. The use of sustained release formulations of minocycline that display slow dissolution of minocycline following administration may be beneficial in reducing the incidence and severity of side effects. Therefore, sustained release capsule dosage forms containing 100 mg minocycline (base) were manufactured and assessed for use as sustained release oral dosage forms of minocycline. Minocycline sustained release capsules were manufactured based on matrix technologies using hydroxypropylmethyl cellulose (HPMC) and Compritol® as release retarding polymers. The rate and extent of minocycline release from the capsules was evaluated using USP Apparatus 1 and samples were analysed using a validated High Performance Liquid Chromatographic (HPLC) method with ultraviolet (UV) detection. Differences in the rate and extent of minocycline release from formulations manufactured using HPMC or Compritol® were influenced by the concentration of polymer used in the formulations. The rate and extent of minocycline release was faster and greater when low concentrations of polymer were used in formulations. The effect of different excipients on the release pattern(s) of minocycline and particularly their potential to optimise minocycline release from experimental formulations was investigated. The use of diluents such as lactose and microcrystalline cellulose (MCC) revealed that lactose facilitated minocycline release when HPMC was used as the polymer matrix. In contrast, the use of lactose as diluent resulted in slower release of minocycline from Compritol® based formulations. The addition of sodium starch glycolate to HPMC based formulations resulted in slower release of minocycline than when no sodium starch glycolate was used. Compritol® based formulations were observed to release minocycline faster following addition of sodium starch glycolate and Poloxamer 188 to experimental formulations. In vitro dissolution profiles were compared to a target or reference profile using the difference and similarity factors, ƒ1 and ƒ2 , and a one way analysis of variance (ANOVA). In addition, the mechanism of minocycline release was elucidated following fitting of dissolution data to the Korsmeyer-Peppas, Higuchi and Zero order models. Minocycline release kinetics were best described by the Korsmeyer-Peppas model and the values of the release exponent, n (italics), revealed that drug release was a result of the combined effects of minocycline diffusion through matrices and erosion of the matrices. These in vitro dissolution profiles were better fit to the Higuchi model than to the Zero order model. Two formulations that displayed a fit to the Zero order model were identified for further studies as potential dosage forms for sustained release minocycline.
- Full Text:
Development of a stability-indicating high performance liquid chromatographic method for the analysis of topiramate and dissolution rate testing in topiramate tablets
- Mohammadi, Ali, Rezanour, Nasrin, Ansari Dogaheh, M, Walker, Roderick B
- Authors: Mohammadi, Ali , Rezanour, Nasrin , Ansari Dogaheh, M , Walker, Roderick B
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:6412 , http://hdl.handle.net/10962/d1006507
- Description: A stability-indicating high performance liquid chromatographic(HPLC) method was developed and validated for the quantitation and dissolution determination of topiramate in tablet dosage forms. An isocratic separation was achieved using a phenyl column with a flow rate of 1 mL/min using UV detection at 264 nm. Topiramate has low UV absorbtivity and was subjected to derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). The mobile phase for the separation consisted of acetonitrile: 50 mM sodium dihydrogen phosphate(NaH2PO4) containing 3 % v/v triethylamine (pH 2.8) in a 48:52 v/v ratio. Topiramate was subjected to oxidation, hydrolysis, photolysis and heat for the purposes of stress testing. Separation was achieved for the parent compound and all the degradation products in an overall analytical run time of approximately 15 min with the parent compound topiramate eluting at approximately 9.2 min. The method was linear over the concentration range of 1-100 μg/mL (r = 0.9996) with limits of quantitation and detection of 1 and 0.3 μg/mL, respectively.
- Full Text:
- Authors: Mohammadi, Ali , Rezanour, Nasrin , Ansari Dogaheh, M , Walker, Roderick B
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:6412 , http://hdl.handle.net/10962/d1006507
- Description: A stability-indicating high performance liquid chromatographic(HPLC) method was developed and validated for the quantitation and dissolution determination of topiramate in tablet dosage forms. An isocratic separation was achieved using a phenyl column with a flow rate of 1 mL/min using UV detection at 264 nm. Topiramate has low UV absorbtivity and was subjected to derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). The mobile phase for the separation consisted of acetonitrile: 50 mM sodium dihydrogen phosphate(NaH2PO4) containing 3 % v/v triethylamine (pH 2.8) in a 48:52 v/v ratio. Topiramate was subjected to oxidation, hydrolysis, photolysis and heat for the purposes of stress testing. Separation was achieved for the parent compound and all the degradation products in an overall analytical run time of approximately 15 min with the parent compound topiramate eluting at approximately 9.2 min. The method was linear over the concentration range of 1-100 μg/mL (r = 0.9996) with limits of quantitation and detection of 1 and 0.3 μg/mL, respectively.
- Full Text:
Development of an IMS Compliant, Cross Platform Client Using the JAIN SIP Applet Phone
- Muswera, Walter T, Terzoli, Alfredo
- Authors: Muswera, Walter T , Terzoli, Alfredo
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431274 , vital:72760 , https://www.cs.ru.ac.za/research/g09M3278/Muswera.pdf
- Description: Several open source SIP/IMS Clients are currently in use in the Rhodes University Convergence Research Group. However, there is no single Client that provides researchers with all the required functionality need-ed to test the applications they have developed. Integrating advanced features into a single Client can help to speed up testing as well as pro-vide a variety of innovative communication services. In this paper we present an overview of two popular SIP/IMS Clients currently in use. We also discuss the features and design architecture of a Client called JAIN SIP Applet Phone (JSAP) which will be used as a basis for the development of a new IMS compliant Client. We then analyse what functionality JSAP lacks and propose features that need to be imple-mented.
- Full Text:
- Authors: Muswera, Walter T , Terzoli, Alfredo
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/431274 , vital:72760 , https://www.cs.ru.ac.za/research/g09M3278/Muswera.pdf
- Description: Several open source SIP/IMS Clients are currently in use in the Rhodes University Convergence Research Group. However, there is no single Client that provides researchers with all the required functionality need-ed to test the applications they have developed. Integrating advanced features into a single Client can help to speed up testing as well as pro-vide a variety of innovative communication services. In this paper we present an overview of two popular SIP/IMS Clients currently in use. We also discuss the features and design architecture of a Client called JAIN SIP Applet Phone (JSAP) which will be used as a basis for the development of a new IMS compliant Client. We then analyse what functionality JSAP lacks and propose features that need to be imple-mented.
- Full Text:
Dialectics of dance and dress: the performative negotiation of Soli girl initiates (Moye) in Zambia
- Authors: Simbao, Ruth K
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147492 , vital:38643 , https://doi.org/10.1162/afar.2010.43.3.64
- Description: During a 2005 dance rehearsal in Nkomeshya Village near Lusaka, Zambia, a group of Soli girl initiates (moye) entered a clearing, slowly moving towards the drummer who beckoned them with her rhythmic eats. The girls per-formed a polite curtseying step, reflecting the meek modesty they are taught to display when they humbly greet elders or their future husbands with downcast eyes.
- Full Text:
- Authors: Simbao, Ruth K
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147492 , vital:38643 , https://doi.org/10.1162/afar.2010.43.3.64
- Description: During a 2005 dance rehearsal in Nkomeshya Village near Lusaka, Zambia, a group of Soli girl initiates (moye) entered a clearing, slowly moving towards the drummer who beckoned them with her rhythmic eats. The girls per-formed a polite curtseying step, reflecting the meek modesty they are taught to display when they humbly greet elders or their future husbands with downcast eyes.
- Full Text:
Differing interpretations of reconciliation in South Africa: a discussion of the home for all campaign
- Authors: Matthews, Sally
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142454 , vital:38081 , DOI:10.1353/trn.2010.0000
- Description: The theme of reconciliation remains an important one in South African politics. The issue of reconciliation was recently highlighted by South African Human Rights Commission chairperson, Jody Kollapen. According to Kollapen, in South Africa we have a problematic narrow interpretation of reconciliation, one that presents reconciliation and transformation as being in opposition to one another. This paper explores some of the debates about reconciliation as a process and then relates these to the Home for All Campaign. This Campaign was aimed at encouraging white South Africans to acknowledge the injustices of the past and to commit themselves to healing divisions and reducing inequalities in contemporary South Africa. It conceived of reconciliation as a process in which the onus is on white South Africans to take the initiative in reconciling with black South Africans. The Campaign received much publicity and provoked debate but never managed to gain the support of a significant number of white South Africans. In this paper, I explore the reasons for the Campaign's failure to meet all of its objectives, relating this to contemporary South African discourse on reconciliation. I argue that the Campaign's interpretation of reconciliation was valuable and necessary and that it remains imperative in South Africa that white South Africans critically reflect upon past and present privileges and take the initiative in processes of inter-racial reconciliation.
- Full Text:
- Authors: Matthews, Sally
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142454 , vital:38081 , DOI:10.1353/trn.2010.0000
- Description: The theme of reconciliation remains an important one in South African politics. The issue of reconciliation was recently highlighted by South African Human Rights Commission chairperson, Jody Kollapen. According to Kollapen, in South Africa we have a problematic narrow interpretation of reconciliation, one that presents reconciliation and transformation as being in opposition to one another. This paper explores some of the debates about reconciliation as a process and then relates these to the Home for All Campaign. This Campaign was aimed at encouraging white South Africans to acknowledge the injustices of the past and to commit themselves to healing divisions and reducing inequalities in contemporary South Africa. It conceived of reconciliation as a process in which the onus is on white South Africans to take the initiative in reconciling with black South Africans. The Campaign received much publicity and provoked debate but never managed to gain the support of a significant number of white South Africans. In this paper, I explore the reasons for the Campaign's failure to meet all of its objectives, relating this to contemporary South African discourse on reconciliation. I argue that the Campaign's interpretation of reconciliation was valuable and necessary and that it remains imperative in South Africa that white South Africans critically reflect upon past and present privileges and take the initiative in processes of inter-racial reconciliation.
- Full Text:
Digital multimedia network with hierarchical parameter control protocol
- Gurdan, Robby, Foss, Richard
- Authors: Gurdan, Robby , Foss, Richard
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427083 , vital:72413 , https://patentimages.storage.googleapis.com/21/04/39/2266c533e05a46/US20100299421A1.pdf
- Description: The present invention relates to a digital multimedia network of apparatuses each comprising a control device, wherein a device parameter of an apparatus is controlled by sending a command message (CMD) to said control device of said apparatus containing a tree-structured hierarchical parameter address (HPA) which consists of parameter grouping identifiers each corresponding to a hierarchy level of a predetermined tree-structured parameter hierarchy used for addressing device parameters throughout said digital multimedia network.
- Full Text:
- Authors: Gurdan, Robby , Foss, Richard
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427083 , vital:72413 , https://patentimages.storage.googleapis.com/21/04/39/2266c533e05a46/US20100299421A1.pdf
- Description: The present invention relates to a digital multimedia network of apparatuses each comprising a control device, wherein a device parameter of an apparatus is controlled by sending a command message (CMD) to said control device of said apparatus containing a tree-structured hierarchical parameter address (HPA) which consists of parameter grouping identifiers each corresponding to a hierarchy level of a predetermined tree-structured parameter hierarchy used for addressing device parameters throughout said digital multimedia network.
- Full Text:
Disjunctures within conventional knowledge of black male homosexual identity in contemporary South Africa
- Authors: Li, Xinling
- Date: 2010
- Subjects: Mead, George Herbert 1863-1931 , Foucault, Michel, 1926-1984 , Butler, Judith, 1956- , Gay men, Black -- South Africa , Lesbians -- South Africa , Gender identity -- South Africa , Homosexuality -- South Africa , Identity (Psychology) -- South Africa , Gender identity -- Social aspects
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3297 , http://hdl.handle.net/10962/d1003085 , Mead, George Herbert 1863-1931 , Foucault, Michel, 1926-1984 , Butler, Judith, 1956- , Gay men, Black -- South Africa , Lesbians -- South Africa , Gender identity -- South Africa , Homosexuality -- South Africa , Identity (Psychology) -- South Africa , Gender identity -- Social aspects
- Description: This thesis provides a sociological understanding of how conventional knowledge of sexuality negates the identity formation of black gay men in contemporary South Africa. It investigates the coming out experiences of six black gay men in order to reveal the disjunctures between being black and being gay. The theoretical formation of disjuncture is pursued through examining a number of sociological, historical, psychoanalytical, and feminist approaches to identity, sexuality, and society; featuring specifically the theories of George Herbert Mead, Michel Foucault, and Judith Butler. The chosen research paradigm is symbolic interactionism, postulating both „pragmatist‟ and „empiricist‟ trends that lead to both interactionist and structuralist forms of argumentation. The interactionist approach to sexuality is central to the deconstruction of sexual conventions. It involves conceptualising modern sexuality in the landscapes of African colonial history and the global gay and lesbian movement. The prescribed literature on homosexuality is thus reviewed in conjunction with the South African gay and lesbian struggle, so as to spawn themes and perspectives for conducting life story interviews. The use of the life story interview favours the participants‟ own view of the studied phenomenon, yet aims to depict the structural influence on homosexual identification. Following the qualitative research tradition, the data analysis is based on the interpretation of narratives. It illustrates interpersonal relationships and microscopic experiences that lead to the self-acceptance and self-actualisation of homosexuality. Within these processes, various disjunctures that exist between the cultural sanction of lifestyle and individual choice, between parents and children, between religious belief and personal desires, and between gender identity and sexual orientation are disclosed. The findings are associated with the historical transformation of masculinity in South Africa, sex role performance, and the heterosexualisation of desire. The solution to the proposed research problem is discussed through concepts of socialisation and gender conformity.
- Full Text:
- Authors: Li, Xinling
- Date: 2010
- Subjects: Mead, George Herbert 1863-1931 , Foucault, Michel, 1926-1984 , Butler, Judith, 1956- , Gay men, Black -- South Africa , Lesbians -- South Africa , Gender identity -- South Africa , Homosexuality -- South Africa , Identity (Psychology) -- South Africa , Gender identity -- Social aspects
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3297 , http://hdl.handle.net/10962/d1003085 , Mead, George Herbert 1863-1931 , Foucault, Michel, 1926-1984 , Butler, Judith, 1956- , Gay men, Black -- South Africa , Lesbians -- South Africa , Gender identity -- South Africa , Homosexuality -- South Africa , Identity (Psychology) -- South Africa , Gender identity -- Social aspects
- Description: This thesis provides a sociological understanding of how conventional knowledge of sexuality negates the identity formation of black gay men in contemporary South Africa. It investigates the coming out experiences of six black gay men in order to reveal the disjunctures between being black and being gay. The theoretical formation of disjuncture is pursued through examining a number of sociological, historical, psychoanalytical, and feminist approaches to identity, sexuality, and society; featuring specifically the theories of George Herbert Mead, Michel Foucault, and Judith Butler. The chosen research paradigm is symbolic interactionism, postulating both „pragmatist‟ and „empiricist‟ trends that lead to both interactionist and structuralist forms of argumentation. The interactionist approach to sexuality is central to the deconstruction of sexual conventions. It involves conceptualising modern sexuality in the landscapes of African colonial history and the global gay and lesbian movement. The prescribed literature on homosexuality is thus reviewed in conjunction with the South African gay and lesbian struggle, so as to spawn themes and perspectives for conducting life story interviews. The use of the life story interview favours the participants‟ own view of the studied phenomenon, yet aims to depict the structural influence on homosexual identification. Following the qualitative research tradition, the data analysis is based on the interpretation of narratives. It illustrates interpersonal relationships and microscopic experiences that lead to the self-acceptance and self-actualisation of homosexuality. Within these processes, various disjunctures that exist between the cultural sanction of lifestyle and individual choice, between parents and children, between religious belief and personal desires, and between gender identity and sexual orientation are disclosed. The findings are associated with the historical transformation of masculinity in South Africa, sex role performance, and the heterosexualisation of desire. The solution to the proposed research problem is discussed through concepts of socialisation and gender conformity.
- Full Text:
Does reservoir trophic status influence the feeding and growth of the sharptooth catfish, Clarias gariepinus (Teleostei: Clariidae)?
- Potts, Warren M, Hecht, Thomas, Andrew, Timothy G
- Authors: Potts, Warren M , Hecht, Thomas , Andrew, Timothy G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124309 , vital:35591 , https://doi.org/10.2989/A JAS.2008.33.2.6.503
- Description: The diet and growth of sharptooth catfish, Clarias gariepinus, in an oligotrophic system (Kat River Reservoir, Eastern Cape, South Africa) were compared to those in a eutrophic system (Laing Reservoir, Eastern Cape) to determine if the trophic status of a waterbody had an effect on the growth rate of the species. In order of importance, the diet of catfish in Kat River Reservoir consisted of fish, insects, zooplankton, plant material and other items, while the diet of catfish in Laing Reservoir consisted of fish, plant material, zooplankton, other vertebrates and insects. The diets of catfish in the two reservoirs had a similarity index of 68.1% and there was no significant difference in their nutritional value. Fish prey was the most important dietary component in both reservoirs. Temperature regime and zooplankton and zoobenthos density were similar in both systems. However, fish prey density was significantly higher in the eutrophic Laing Reservoir and catfish grew significantly faster in that system. The slower growth rate in Kat River Reservoir was attributed to the higher energy costs associated with the capture of fish prey, which was less abundant than in Laing Reservoir. Trophic status therefore had an indirect effect on catfish growth by influencing the availability of fish prey.
- Full Text:
- Authors: Potts, Warren M , Hecht, Thomas , Andrew, Timothy G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124309 , vital:35591 , https://doi.org/10.2989/A JAS.2008.33.2.6.503
- Description: The diet and growth of sharptooth catfish, Clarias gariepinus, in an oligotrophic system (Kat River Reservoir, Eastern Cape, South Africa) were compared to those in a eutrophic system (Laing Reservoir, Eastern Cape) to determine if the trophic status of a waterbody had an effect on the growth rate of the species. In order of importance, the diet of catfish in Kat River Reservoir consisted of fish, insects, zooplankton, plant material and other items, while the diet of catfish in Laing Reservoir consisted of fish, plant material, zooplankton, other vertebrates and insects. The diets of catfish in the two reservoirs had a similarity index of 68.1% and there was no significant difference in their nutritional value. Fish prey was the most important dietary component in both reservoirs. Temperature regime and zooplankton and zoobenthos density were similar in both systems. However, fish prey density was significantly higher in the eutrophic Laing Reservoir and catfish grew significantly faster in that system. The slower growth rate in Kat River Reservoir was attributed to the higher energy costs associated with the capture of fish prey, which was less abundant than in Laing Reservoir. Trophic status therefore had an indirect effect on catfish growth by influencing the availability of fish prey.
- Full Text:
Ecological impacts of small dams on South African rivers Part 1: Drivers of change–water quantity and quality
- Mantel, Sukhmani K, Hughes, Denis A, Muller, Nikite W J
- Authors: Mantel, Sukhmani K , Hughes, Denis A , Muller, Nikite W J
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438099 , vital:73435 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2398.pdf
- Description: Impacts of large dams are well-known and quantifiable, while small dams have generally been perceived as benign, both socially and envi-ronmentally. The present study quantifies the cumulative impacts of small dams on the water quality (physico-chemistry and invertebrate biotic indices) and quantity (discharge) of downstream rivers in 2 South African regions. The information from 2 South African national data-bases was used for evaluating the cumulative impacts on water quality and quantity. Physico-chemistry and biological data were obtained from the River Health Programme, and discharge data at stream flow gauges was obtained from the Hydrological Information System. Multivariate analyses were conducted to establish broad patterns for cumulative impacts of small dams across the 2 regions–Western Cape (winter rain-fall, temperate, south-western coast) and Mpumalanga (summer rain-fall, tropical, eastern coast). Multivariate analyses found that the chang-es in macroinvertebrate indices and the stream’s physico-chemistry were more strongly correlated with the density of small dams in the catchment (as a measure of cumulative impact potential) relative to the storage capacity of large dams. T-tests on the data, not including sam-ples with upstream large dams, indicated that the high density of small dams significantly reduced low flows and increased certain physico-chemistry variables (particularly total dissolved salts) in both the re-gions, along with associated significant reductions in a macroinverte-brate index (SASS4 average score per taxon). Regional differences were apparent in the results for discharge reductions and the macroin-vertebrate index. The results suggest that the cumulative effect of a high number of small dams is impacting the quality and quantity of wa-ters in South African rivers and that these impacts need to be systemat-ically incorporated into the monitoring protocol of the environmental wa-ter requirements.
- Full Text:
- Authors: Mantel, Sukhmani K , Hughes, Denis A , Muller, Nikite W J
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438099 , vital:73435 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2398.pdf
- Description: Impacts of large dams are well-known and quantifiable, while small dams have generally been perceived as benign, both socially and envi-ronmentally. The present study quantifies the cumulative impacts of small dams on the water quality (physico-chemistry and invertebrate biotic indices) and quantity (discharge) of downstream rivers in 2 South African regions. The information from 2 South African national data-bases was used for evaluating the cumulative impacts on water quality and quantity. Physico-chemistry and biological data were obtained from the River Health Programme, and discharge data at stream flow gauges was obtained from the Hydrological Information System. Multivariate analyses were conducted to establish broad patterns for cumulative impacts of small dams across the 2 regions–Western Cape (winter rain-fall, temperate, south-western coast) and Mpumalanga (summer rain-fall, tropical, eastern coast). Multivariate analyses found that the chang-es in macroinvertebrate indices and the stream’s physico-chemistry were more strongly correlated with the density of small dams in the catchment (as a measure of cumulative impact potential) relative to the storage capacity of large dams. T-tests on the data, not including sam-ples with upstream large dams, indicated that the high density of small dams significantly reduced low flows and increased certain physico-chemistry variables (particularly total dissolved salts) in both the re-gions, along with associated significant reductions in a macroinverte-brate index (SASS4 average score per taxon). Regional differences were apparent in the results for discharge reductions and the macroin-vertebrate index. The results suggest that the cumulative effect of a high number of small dams is impacting the quality and quantity of wa-ters in South African rivers and that these impacts need to be systemat-ically incorporated into the monitoring protocol of the environmental wa-ter requirements.
- Full Text:
Ecological impacts of small dams on South African rivers Part 2: Biotic response – abundance and composition of macroinvertebrate communities
- Mantel, Sukhmani K, Muller, Nikite W J, Hughes, Denis A
- Authors: Mantel, Sukhmani K , Muller, Nikite W J , Hughes, Denis A
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:7095 , http://hdl.handle.net/10962/d1012437
- Description: This paper investigates the cumulative impacts of small dams on invertebrate communities in 2 regions of South Africa – the Western Cape and Mpumalanga. Previous research found reduced discharge, increased total dissolved salts, and a decrease in average score per taxon (ASPT; collected using SASS4 methods) at sites with high density of small dams in their catchment. These changes in ASPT are investigated using the invertebrate abundance data available in the River Health Programme. Multivariate analyses found differences in invertebrate communities in rivers with high densities of small dams in their catchment in foothill-gravel streams (in both Western Cape and Mpumalanga) and in foothill-cobble streams (in Western Cape only). Opportunistic taxa that are tolerant of pollution, and capable of exploiting various habitats, and those that prefer slower currents increased in numbers, while other taxa that are sensitive to pollution and disturbance declined in numbers. Some regional differences were noted possibly reflecting climatic differences between the regions. Since the results of this study are correlative, it highlights the need for a systematic (by sites and seasons) and detailed (at species level) collection of data to verify the results of cumulative effects of small dams. This can further the development of a framework for small-dam construction and management that will limit their impact on river catchments.
- Full Text:
- Authors: Mantel, Sukhmani K , Muller, Nikite W J , Hughes, Denis A
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:7095 , http://hdl.handle.net/10962/d1012437
- Description: This paper investigates the cumulative impacts of small dams on invertebrate communities in 2 regions of South Africa – the Western Cape and Mpumalanga. Previous research found reduced discharge, increased total dissolved salts, and a decrease in average score per taxon (ASPT; collected using SASS4 methods) at sites with high density of small dams in their catchment. These changes in ASPT are investigated using the invertebrate abundance data available in the River Health Programme. Multivariate analyses found differences in invertebrate communities in rivers with high densities of small dams in their catchment in foothill-gravel streams (in both Western Cape and Mpumalanga) and in foothill-cobble streams (in Western Cape only). Opportunistic taxa that are tolerant of pollution, and capable of exploiting various habitats, and those that prefer slower currents increased in numbers, while other taxa that are sensitive to pollution and disturbance declined in numbers. Some regional differences were noted possibly reflecting climatic differences between the regions. Since the results of this study are correlative, it highlights the need for a systematic (by sites and seasons) and detailed (at species level) collection of data to verify the results of cumulative effects of small dams. This can further the development of a framework for small-dam construction and management that will limit their impact on river catchments.
- Full Text:
Ecological impacts of small dams on South African rivers Part 2: Biotic response–abundance and composition of macroinvertebrate communities
- Mantel, Sukhmani K, Muller, Nikite W J, Hughes, Denis A
- Authors: Mantel, Sukhmani K , Muller, Nikite W J , Hughes, Denis A
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438087 , vital:73434 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2354.pdf
- Description: This paper investigates the cumulative impacts of small dams on inver-tebrate communities in 2 regions of South Africa–the Western Cape and Mpumalanga. Previous research found reduced discharge, in-creased total dissolved salts, and a decrease in average score per tax-on (ASPT; collected using SASS4 methods) at sites with high density of small dams in their catchment. These changes in ASPT are investigat-ed using the invertebrate abundance data available in the River Health Programme. Multivariate analyses found differences in invertebrate communities in rivers with high densities of small dams in their catch-ment in foothill-gravel streams (in both Western Cape and Mpuma-langa) and in foothill-cobble streams (in Western Cape only). Opportun-istic taxa that are tolerant of pollution, and capable of exploiting various habitats, and those that prefer slower currents increased in numbers, while other taxa that are sensitive to pollution and disturbance declined in numbers. Some regional differences were noted possibly reflecting climatic differences between the regions. Since the results of this study are correlative, it highlights the need for a systematic (by sites and sea-sons) and detailed (at species level) collection of data to verify the re-sults of cumulative effects of small dams. This can further the devel-opment of a framework for small-dam construction and management that will limit their impact on river catchments.
- Full Text:
- Authors: Mantel, Sukhmani K , Muller, Nikite W J , Hughes, Denis A
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438087 , vital:73434 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2354.pdf
- Description: This paper investigates the cumulative impacts of small dams on inver-tebrate communities in 2 regions of South Africa–the Western Cape and Mpumalanga. Previous research found reduced discharge, in-creased total dissolved salts, and a decrease in average score per tax-on (ASPT; collected using SASS4 methods) at sites with high density of small dams in their catchment. These changes in ASPT are investigat-ed using the invertebrate abundance data available in the River Health Programme. Multivariate analyses found differences in invertebrate communities in rivers with high densities of small dams in their catch-ment in foothill-gravel streams (in both Western Cape and Mpuma-langa) and in foothill-cobble streams (in Western Cape only). Opportun-istic taxa that are tolerant of pollution, and capable of exploiting various habitats, and those that prefer slower currents increased in numbers, while other taxa that are sensitive to pollution and disturbance declined in numbers. Some regional differences were noted possibly reflecting climatic differences between the regions. Since the results of this study are correlative, it highlights the need for a systematic (by sites and sea-sons) and detailed (at species level) collection of data to verify the re-sults of cumulative effects of small dams. This can further the devel-opment of a framework for small-dam construction and management that will limit their impact on river catchments.
- Full Text:
Ecology and degree of specialization of South African milkweeds with diverse pollination systems
- Authors: Coombs, Gareth
- Date: 2010
- Subjects: Milkweeds -- South Africa Milkweeds -- South Africa -- Ecology Milkweeds -- South Africa -- Pollination Allee effect Self-pollination Pollination by insects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4189 , http://hdl.handle.net/10962/d1003758
- Description: Like orchids, the complexity of flowers found in asclepiads (Asclepiadoideae, Apocynaceae) and the fact that pollen is presented as pollinaria, offers excellent opportunities to study various aspects of plant-pollinator interactions. In this thesis I investigated two broad themes: ecological aspects of the pollination biology of hymenopteran and fly-pollinated asclepiads as well as the degree of specialization to certain pollinators in these species. Colonizing plants often reproduce through self-pollination, or have highly generalized pollination systems, or both. These characteristics facilitate establishment in small founding populations and generates the prediction that reproductive success should be independent of population size in these species. Chapter one examines the pollination biology of Gomphocarpus physocarpus, an indigenous, weedy species and investigates the relationship between reproductive success and population size. In this species, there is no evidence of an Allee effect and reproductive success is not correlated with population size. In addition G. physocarpus is not capable of self-pollination, suggesting it is completely reliant on pollinators for seed set. The lack of a relationship between pollination success and population size is therefore likely explained by the generalized wasp pollination system of this species. Several milkweeds are invasive outside of their native ranges. Invasive species either need to co-opt native pollinators in order to reproduce or reduce their reliance on pollinators through having the ability to self-pollinate. Co-opting native pollinators is expected to be easier in species that have generalized pollination systems, alternatively species with specialized flower morphologies need to rely on similar functional groups of pollinators to be present within the invaded range. Chapter two investigates the pollination biology and pollination success of the invasive milkweed, Araujia sericifera, and finds that in South Africa, this species is visited mainly by native honeybees and nocturnal moths. Moths however contribute little to pollen removal, and deposition. Based on the apparent morphological mismatch between the flower of A. sericifera and native honeybees, I propose that the native pollinators of this species are likely to be larger Hymenoptera (e.g. Bumblebees). Data from a breeding system study, indicated that this species is not capable of automatic self-pollination, but could set fruit from geitonogamous self-pollinations pointing to the importance of native pollinators for successful reproduction. The pollinaria of milkweeds can accumulate on pollinators to form pollen masses large enough to physically interfere with the foraging behaviour of pollinating insects. In chapter three I describe the pollination biology of Cynanchum ellipticum and find that this species is mainly pollinated by honeybees although this species is visited by several other members of Hymenoptera, Lepidoptera and Diptera. Due to the structure of the pollinaria, these chain together relatively efficiently and frequently form large pollinarium loads on the mouthparts of honeybees. However there is little evidence that these pollinarium loads influence the foraging times of pollinators and only a few individual honeybees exhibited longer foraging times and most honeybees were unaffected by the presence of large pollinarium loads. Within the genus Cynanchum there is large variation in the gynostegium structure that may influence the pattern of pollinarium loading on pollinators as well as pollen reception as shown in chapter three. In Chapter four, the pollination biology of Cynanchum obtusifolium is examined, and like that of C. ellipticum, this species is visited by a wide diversity of pollinators but honeybees appear to be the primary pollinators. More importantly this species is shown to be andromonoecious and produces two morphologically different flower types, that may be distinguished based on differences in the gynostegium structure. These two types of flower could mainly be distinguished by the length of the anther wings. I found that flowers with short anther wings function as male flowers by only exporting- and rarely receiving pollinia. Flowers with longer anther wings function as hermaphrodite flowers and can both export and receive pollinia. The ratio of male to hermaphrodite flowers varied at different times during the flowering season, but preliminary data suggested that this was not related to levels of pollination success. The genera Stapelia and Ceropegia are well known for their intricate floral adaptations that mimic the brood and feeding substrates of pollinating flies. Despite several studies that have documented the various adaptations to fly pollination in different species, there is a lack of natural history studies documenting different flower visitors, pollen loads and long term levels of pollination success in these species. In Chapter six I document the pollination biology of Ceropegia ampliata by documenting different pollinators and quantifying average levels of pollination success and the nectar reward. I also experimentally manipulated the trapping hairs of this species to determine whether trapping hairs influence average levels of pollen export and receipt. I show that Ceropegia ampliata is pollinated by a generalist guild of flies (mainly Tachinidae, Sarcophagidae, Muscidae and Lauxaniidae) and produces minute quantities of relatively dilute nectar as a reward. Pollination success was generally low in this species and increases periodically suggesting that the abundance of pollinators is patchy. I found that flowers with trapping hairs that had already wilted had higher levels of pollinarium removal than flowers with erect hairs, however experimentally removing the hairs had no significant effect on pollen export and receipt. In Chapter seven, I document the pollinators, pollen loads and long term levels of pollination success in Stapelia hirsuta var. bayllissi, a rare sapromyiophilous stapeliad. I find that, in contrast to C. ampliata, this species was specialized to pollination by small flies of the family Anthomyiidae. Similar to the results from Chapter seven, I find that long term levels of pollination success were typically low but could increase periodically, although such increases were generally unpredictable. There are currently very few records documenting pollinator interactions in the Periplocoideae. Many species within this subfamily exhibit open-access flowers suggestive of pollination by short-tongued insects. I investigated the pollination biology of Chlorocyathus lobulata, a rare species with a highly localized distribution. I aimed to determine the pollinators, average levels of pollination success and demography of this species in order to determine whether this rare species is suffering from the collapse of a highly specialized pollinator mutualism. I also quantified the high incidence of flower herbivory caused by larvae of the moth, Bocchoris onychinalis. I find that C. lobulata has a highly generalized fly pollination system and average levels of pollination success suggested that a large proportion of flowers had pollen removed and deposited suggesting that this species is not experiencing pollination failure. The large numbers of juveniles present also indicated that recruitment is taking place.
- Full Text:
- Authors: Coombs, Gareth
- Date: 2010
- Subjects: Milkweeds -- South Africa Milkweeds -- South Africa -- Ecology Milkweeds -- South Africa -- Pollination Allee effect Self-pollination Pollination by insects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4189 , http://hdl.handle.net/10962/d1003758
- Description: Like orchids, the complexity of flowers found in asclepiads (Asclepiadoideae, Apocynaceae) and the fact that pollen is presented as pollinaria, offers excellent opportunities to study various aspects of plant-pollinator interactions. In this thesis I investigated two broad themes: ecological aspects of the pollination biology of hymenopteran and fly-pollinated asclepiads as well as the degree of specialization to certain pollinators in these species. Colonizing plants often reproduce through self-pollination, or have highly generalized pollination systems, or both. These characteristics facilitate establishment in small founding populations and generates the prediction that reproductive success should be independent of population size in these species. Chapter one examines the pollination biology of Gomphocarpus physocarpus, an indigenous, weedy species and investigates the relationship between reproductive success and population size. In this species, there is no evidence of an Allee effect and reproductive success is not correlated with population size. In addition G. physocarpus is not capable of self-pollination, suggesting it is completely reliant on pollinators for seed set. The lack of a relationship between pollination success and population size is therefore likely explained by the generalized wasp pollination system of this species. Several milkweeds are invasive outside of their native ranges. Invasive species either need to co-opt native pollinators in order to reproduce or reduce their reliance on pollinators through having the ability to self-pollinate. Co-opting native pollinators is expected to be easier in species that have generalized pollination systems, alternatively species with specialized flower morphologies need to rely on similar functional groups of pollinators to be present within the invaded range. Chapter two investigates the pollination biology and pollination success of the invasive milkweed, Araujia sericifera, and finds that in South Africa, this species is visited mainly by native honeybees and nocturnal moths. Moths however contribute little to pollen removal, and deposition. Based on the apparent morphological mismatch between the flower of A. sericifera and native honeybees, I propose that the native pollinators of this species are likely to be larger Hymenoptera (e.g. Bumblebees). Data from a breeding system study, indicated that this species is not capable of automatic self-pollination, but could set fruit from geitonogamous self-pollinations pointing to the importance of native pollinators for successful reproduction. The pollinaria of milkweeds can accumulate on pollinators to form pollen masses large enough to physically interfere with the foraging behaviour of pollinating insects. In chapter three I describe the pollination biology of Cynanchum ellipticum and find that this species is mainly pollinated by honeybees although this species is visited by several other members of Hymenoptera, Lepidoptera and Diptera. Due to the structure of the pollinaria, these chain together relatively efficiently and frequently form large pollinarium loads on the mouthparts of honeybees. However there is little evidence that these pollinarium loads influence the foraging times of pollinators and only a few individual honeybees exhibited longer foraging times and most honeybees were unaffected by the presence of large pollinarium loads. Within the genus Cynanchum there is large variation in the gynostegium structure that may influence the pattern of pollinarium loading on pollinators as well as pollen reception as shown in chapter three. In Chapter four, the pollination biology of Cynanchum obtusifolium is examined, and like that of C. ellipticum, this species is visited by a wide diversity of pollinators but honeybees appear to be the primary pollinators. More importantly this species is shown to be andromonoecious and produces two morphologically different flower types, that may be distinguished based on differences in the gynostegium structure. These two types of flower could mainly be distinguished by the length of the anther wings. I found that flowers with short anther wings function as male flowers by only exporting- and rarely receiving pollinia. Flowers with longer anther wings function as hermaphrodite flowers and can both export and receive pollinia. The ratio of male to hermaphrodite flowers varied at different times during the flowering season, but preliminary data suggested that this was not related to levels of pollination success. The genera Stapelia and Ceropegia are well known for their intricate floral adaptations that mimic the brood and feeding substrates of pollinating flies. Despite several studies that have documented the various adaptations to fly pollination in different species, there is a lack of natural history studies documenting different flower visitors, pollen loads and long term levels of pollination success in these species. In Chapter six I document the pollination biology of Ceropegia ampliata by documenting different pollinators and quantifying average levels of pollination success and the nectar reward. I also experimentally manipulated the trapping hairs of this species to determine whether trapping hairs influence average levels of pollen export and receipt. I show that Ceropegia ampliata is pollinated by a generalist guild of flies (mainly Tachinidae, Sarcophagidae, Muscidae and Lauxaniidae) and produces minute quantities of relatively dilute nectar as a reward. Pollination success was generally low in this species and increases periodically suggesting that the abundance of pollinators is patchy. I found that flowers with trapping hairs that had already wilted had higher levels of pollinarium removal than flowers with erect hairs, however experimentally removing the hairs had no significant effect on pollen export and receipt. In Chapter seven, I document the pollinators, pollen loads and long term levels of pollination success in Stapelia hirsuta var. bayllissi, a rare sapromyiophilous stapeliad. I find that, in contrast to C. ampliata, this species was specialized to pollination by small flies of the family Anthomyiidae. Similar to the results from Chapter seven, I find that long term levels of pollination success were typically low but could increase periodically, although such increases were generally unpredictable. There are currently very few records documenting pollinator interactions in the Periplocoideae. Many species within this subfamily exhibit open-access flowers suggestive of pollination by short-tongued insects. I investigated the pollination biology of Chlorocyathus lobulata, a rare species with a highly localized distribution. I aimed to determine the pollinators, average levels of pollination success and demography of this species in order to determine whether this rare species is suffering from the collapse of a highly specialized pollinator mutualism. I also quantified the high incidence of flower herbivory caused by larvae of the moth, Bocchoris onychinalis. I find that C. lobulata has a highly generalized fly pollination system and average levels of pollination success suggested that a large proportion of flowers had pollen removed and deposited suggesting that this species is not experiencing pollination failure. The large numbers of juveniles present also indicated that recruitment is taking place.
- Full Text: