Spectroscopic and nonlinear optical characterisation of alpha substituted binuclear phthalocyanines
- Authors: Ngubeni, Grace Nomthandazo
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5038 , vital:20757
- Full Text:
- Authors: Ngubeni, Grace Nomthandazo
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5038 , vital:20757
- Full Text:
Synthesis and bioassay of rationally designed DXR inhibitors as potential antimalarial lead compounds
- Authors: Nokalipa, Iviwe Cwaita
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4888 , vital:20740
- Description: Globally, the eradication of malaria has been challenging due to the problem of resistance that past and currently available drugs exhibit. This is exacerbated by the inherent need for anti-malarial drugs to be affordable to the poverty-stricken majority that is primarily affected by this burden. This research has focused on the development of potential inhibitors of 1-deoxy-D- xylulose-5 phosphate reductoisomerase (DXR), an essential enzyme in the mevalonate- independent pathway for the biosynthesis of isoprenoids in Plasmodium falciparum. DXR mediates the isomerisation and reduction of 1-deoxy-D-xylulose-5-phosphate into 2-C- methyl-D-erithrytol 4-phosphate. This enzyme has been determined to be a target for the development of novel antimalarial agents and extensive molecular modelling has been undertaken to develop inhibitors that fit into the DXR active site. The in silico docking data have been used to inform the design and synthesis of various N-benzyl-substituted phosphoramidate ligands that were determined to have potential as novel substrate mimics of fosmidomycin, a known DXR inhibitor. Synthesis of the N-benzyl-substituted phosphoramidate ligands involved a nine-step sequence commencing from diethyl phosphoramidate. In all, some 40 compounds have been prepared, some of them new, and were fully characterized using NMR. Attention has also been given to the mass spectrometric fragmentation patterns exhibited by selected intermediates. Four of the final products were evaluated for in vitro antimalarial activity using a PLDH assay and exhibited IC50 values < 100 µM.
- Full Text:
- Authors: Nokalipa, Iviwe Cwaita
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4888 , vital:20740
- Description: Globally, the eradication of malaria has been challenging due to the problem of resistance that past and currently available drugs exhibit. This is exacerbated by the inherent need for anti-malarial drugs to be affordable to the poverty-stricken majority that is primarily affected by this burden. This research has focused on the development of potential inhibitors of 1-deoxy-D- xylulose-5 phosphate reductoisomerase (DXR), an essential enzyme in the mevalonate- independent pathway for the biosynthesis of isoprenoids in Plasmodium falciparum. DXR mediates the isomerisation and reduction of 1-deoxy-D-xylulose-5-phosphate into 2-C- methyl-D-erithrytol 4-phosphate. This enzyme has been determined to be a target for the development of novel antimalarial agents and extensive molecular modelling has been undertaken to develop inhibitors that fit into the DXR active site. The in silico docking data have been used to inform the design and synthesis of various N-benzyl-substituted phosphoramidate ligands that were determined to have potential as novel substrate mimics of fosmidomycin, a known DXR inhibitor. Synthesis of the N-benzyl-substituted phosphoramidate ligands involved a nine-step sequence commencing from diethyl phosphoramidate. In all, some 40 compounds have been prepared, some of them new, and were fully characterized using NMR. Attention has also been given to the mass spectrometric fragmentation patterns exhibited by selected intermediates. Four of the final products were evaluated for in vitro antimalarial activity using a PLDH assay and exhibited IC50 values < 100 µM.
- Full Text:
Sex work as a livelihood strategy in the border town of Beitbridge, Zimbabwe
- Authors: Takawira, Wadzanai Michelle
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/3801 , vital:20544
- Description: Zimbabwe is experiencing an ongoing downward spiral in its national economy, dating back to the early 1990s. The demise of the country’s formal economy has led to unprecedented growth in informal economic activities including illegal forms such as sex work. The thesis seeks to understand and explain sex work as a livelihood strategy in Zimbabwe with particular reference to the border town of Beitbridge. In understanding sex work as a livelihood strategy in Beitbridge, the thesis adopts a livelihoods framework in providing key insights into the daily lives of sex workers including the context of vulnerability in which they live and work as well as the challenges they face constantly. In addition, because of the significance of patriarchy in shaping the lives of women and specifically sex workers in Zimbabwe, the feminist theory is used as a secondary theoretical framework. The fieldwork for the study is based on informal interviews and focus group discussions with sex workers as well as observation. Diverse and interrelated themes are covered in examining the livelihoods of sex workers in Beitbridge, and these include sex worker income and expenditure, the motivations underpinning entry into sex work, the home origins of sex workers and their ongoing linkages with their areas of origin, occupational hazards such as client violence and health risks, stigma and discrimination of sex workers, and sex worker solidarity. Though the lives of the sex workers in Beitbridge are marked by precariousness and uncertainty, it is concluded that sex workers are not mere victims of their historical and social circumstances as they are actively engaged in constructing their livelihoods.
- Full Text:
- Authors: Takawira, Wadzanai Michelle
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/3801 , vital:20544
- Description: Zimbabwe is experiencing an ongoing downward spiral in its national economy, dating back to the early 1990s. The demise of the country’s formal economy has led to unprecedented growth in informal economic activities including illegal forms such as sex work. The thesis seeks to understand and explain sex work as a livelihood strategy in Zimbabwe with particular reference to the border town of Beitbridge. In understanding sex work as a livelihood strategy in Beitbridge, the thesis adopts a livelihoods framework in providing key insights into the daily lives of sex workers including the context of vulnerability in which they live and work as well as the challenges they face constantly. In addition, because of the significance of patriarchy in shaping the lives of women and specifically sex workers in Zimbabwe, the feminist theory is used as a secondary theoretical framework. The fieldwork for the study is based on informal interviews and focus group discussions with sex workers as well as observation. Diverse and interrelated themes are covered in examining the livelihoods of sex workers in Beitbridge, and these include sex worker income and expenditure, the motivations underpinning entry into sex work, the home origins of sex workers and their ongoing linkages with their areas of origin, occupational hazards such as client violence and health risks, stigma and discrimination of sex workers, and sex worker solidarity. Though the lives of the sex workers in Beitbridge are marked by precariousness and uncertainty, it is concluded that sex workers are not mere victims of their historical and social circumstances as they are actively engaged in constructing their livelihoods.
- Full Text:
A case study of organisational change in an employee wellness company and its effects on job satisfaction and organisational climate
- Authors: Kassiem, Wahib
- Date: 2015
- Subjects: Organizational change -- South Africa -- Case studies
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:844 , http://hdl.handle.net/10962/d1016404
- Description: The modern era has brought the phenomenon of organisational change closer to the average person. With the recent financial crisis placing more strain on businesses, organisations are always under pressure to review their business models in order to deliver a sustainable operational model and as result, hopefully a sustainable competitive advantage. In order to remain competitive, the leadership team has to constantly seek ways of differentiating their organisations from others with similar product offerings. When these changes are initiated, there is no doubt that the leadership gave extensive thought prior to execution. However, their motives are not always clear to their most important constitution, their employees. Often when these changes are implemented, employees believe that they’ve been left out of the decision making process. Furthermore, post change review with employees are also not given enough thought and are often not done. This research used qualitative research methods to establish how employees experience job satisfaction and organisational climate subsequent to changes that transpired within their work environment. Semi-structured interviews and document analysis were used to collect data. The interviews were constructed by expanding upon well-documented quantitative dimensions of these behavioural variables. Questions were developed focusing on these dimensions in line with the changes experienced. The sample consisted of nine employees at an employee wellness organisation in Roodepoort, Gauteng. There is evidence to show that in this short period of two years (May 2012 to June 2014), by implementing various changes, the new leadership has improved the financial viability of the organisation. However, insights from the interviews point to a number of areas where the leadership and management structures have to exert more effort. Communication processes have to be reviewed, especially to lower levels. As there exists limited opportunities for promotion, investigations into expanding existing roles, again at the lower levels may assist in raising job satisfaction levels. Employees felt that support structures are severely lacking when significant changes affecting them are implemented. A climate for innovation and risk taking has to be considered which, if instituted, could aid the organisation in setting the pace for the organisational wellness industry. The structure adopted for this research consists of three sections. Section one follows the evaluation report format, with the literature review and research methodology sections following thereafter. By making use of established literature as a basis, the findings and recommendations are therefore not exclusively applicable to this organisation. Hence other organisations intending similar change initiatives could benefit from this research.
- Full Text:
- Authors: Kassiem, Wahib
- Date: 2015
- Subjects: Organizational change -- South Africa -- Case studies
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:844 , http://hdl.handle.net/10962/d1016404
- Description: The modern era has brought the phenomenon of organisational change closer to the average person. With the recent financial crisis placing more strain on businesses, organisations are always under pressure to review their business models in order to deliver a sustainable operational model and as result, hopefully a sustainable competitive advantage. In order to remain competitive, the leadership team has to constantly seek ways of differentiating their organisations from others with similar product offerings. When these changes are initiated, there is no doubt that the leadership gave extensive thought prior to execution. However, their motives are not always clear to their most important constitution, their employees. Often when these changes are implemented, employees believe that they’ve been left out of the decision making process. Furthermore, post change review with employees are also not given enough thought and are often not done. This research used qualitative research methods to establish how employees experience job satisfaction and organisational climate subsequent to changes that transpired within their work environment. Semi-structured interviews and document analysis were used to collect data. The interviews were constructed by expanding upon well-documented quantitative dimensions of these behavioural variables. Questions were developed focusing on these dimensions in line with the changes experienced. The sample consisted of nine employees at an employee wellness organisation in Roodepoort, Gauteng. There is evidence to show that in this short period of two years (May 2012 to June 2014), by implementing various changes, the new leadership has improved the financial viability of the organisation. However, insights from the interviews point to a number of areas where the leadership and management structures have to exert more effort. Communication processes have to be reviewed, especially to lower levels. As there exists limited opportunities for promotion, investigations into expanding existing roles, again at the lower levels may assist in raising job satisfaction levels. Employees felt that support structures are severely lacking when significant changes affecting them are implemented. A climate for innovation and risk taking has to be considered which, if instituted, could aid the organisation in setting the pace for the organisational wellness industry. The structure adopted for this research consists of three sections. Section one follows the evaluation report format, with the literature review and research methodology sections following thereafter. By making use of established literature as a basis, the findings and recommendations are therefore not exclusively applicable to this organisation. Hence other organisations intending similar change initiatives could benefit from this research.
- Full Text:
Inclusion and differentiation: an examination of teachers' experience and perspectives in working with difference and learner potential in grade 1 mathematics classrooms in three schools in Grahamstown
- Whittington-Jones, Alexandra
- Authors: Whittington-Jones, Alexandra
- Date: 2013
- Subjects: Gifted children -- Education (Primary) -- Research -- South Africa -- Grahamstown Inclusive education -- Research -- South Africa -- Grahamstown Mainstreaming in education -- Research -- South Africa -- Grahamstown Special education -- Research -- South Africa -- Grahamstown Curriculum planning -- Education (Primary) -- South Africa -- Grahamstown Education, Primary -- Study and teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1893 , http://hdl.handle.net/10962/d1006088
- Description: In South Africa, in July 2001, the National Department of Education released White Paper 6 which underpins the notion of inclusive education. It states that the needs of all children should be catered for within the South African educational framework. Subsequent guidelines from the Department (2005; 2012) also provide a strong focus on understanding individual children’s learning styles and explain the concept and application of children’s multiple intelligences. However, on closer examination, it seems that the inclusive education, as well as barriers to learning referred to in the abovementioned guidelines, are indicated to mean catering for children at the lower-ability end of the learning spectrum. This research begins to explore the notion that high potential children might require special attention, though not at the expense of those with learning impairments. An education system that provides inclusive education to children at both the lower and higher ends of the learning spectrum would be more equitable, and would give all children an equal chance of reaching their full potential. One possible strategy for accommodating the diverse needs of learners is through differentiation (Department of Education, 2005). Differentiation is a way of teaching that aims to provide stimulating and enriching learning environments to a diverse group of children within a classroom. This might be achieved by separating the class into smaller groups based on ability, or by providing children with different tasks at the same time, with the same learning objectives but at differing cognitive levels (Rogers, 2007). Vygotsky’s work on the Zone of Proximal Development (ZPD) and mediation provides a theoretical framework for proposing differentiation as a strategy. The data was gathered through an in-depth examination (using a combination of classroom observations, document analysis and teacher interviews) of mathematics teaching in Grade 1 in three schools in Grahamstown. My analysis was based on Vygotsky’s theories (the main tenets of which were the ZPD and scaffolding, as well as the role of socio-culture in learning), using Tomlinson’s (1999) differentiated instruction framework to provide structure to the study. The following themes emerged from the data: a focus on the teachers’ understandings of differentiation; the use of grouping as a superficial form of differentiation; a lack of teacher preparation and understanding in relation to task differentiation; and an underlying sense of ‘sameness’ in teachers’ understanding of their learners. In addition to the above, I did not observe evidence of real differentiation for high potential children and hope that this research contributes to extending teachers’ training (both academic and in-service) in this area, convincing teachers of the existence and importance of critical thinking abilities in our youngest learners, and initiating a move towards the drafting of Individual Education Plans for all our learners. During the period of my research I have been convinced that the use of differentiated instruction in classrooms is the way forward in educational thinking, particularly as it relates to the notion of inclusive learning. Clearly there are challenges to be addressed in terms of school timetables, curricula, teachers’ time frames and past education system inequalities such as we have here in South Africa.
- Full Text:
- Authors: Whittington-Jones, Alexandra
- Date: 2013
- Subjects: Gifted children -- Education (Primary) -- Research -- South Africa -- Grahamstown Inclusive education -- Research -- South Africa -- Grahamstown Mainstreaming in education -- Research -- South Africa -- Grahamstown Special education -- Research -- South Africa -- Grahamstown Curriculum planning -- Education (Primary) -- South Africa -- Grahamstown Education, Primary -- Study and teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1893 , http://hdl.handle.net/10962/d1006088
- Description: In South Africa, in July 2001, the National Department of Education released White Paper 6 which underpins the notion of inclusive education. It states that the needs of all children should be catered for within the South African educational framework. Subsequent guidelines from the Department (2005; 2012) also provide a strong focus on understanding individual children’s learning styles and explain the concept and application of children’s multiple intelligences. However, on closer examination, it seems that the inclusive education, as well as barriers to learning referred to in the abovementioned guidelines, are indicated to mean catering for children at the lower-ability end of the learning spectrum. This research begins to explore the notion that high potential children might require special attention, though not at the expense of those with learning impairments. An education system that provides inclusive education to children at both the lower and higher ends of the learning spectrum would be more equitable, and would give all children an equal chance of reaching their full potential. One possible strategy for accommodating the diverse needs of learners is through differentiation (Department of Education, 2005). Differentiation is a way of teaching that aims to provide stimulating and enriching learning environments to a diverse group of children within a classroom. This might be achieved by separating the class into smaller groups based on ability, or by providing children with different tasks at the same time, with the same learning objectives but at differing cognitive levels (Rogers, 2007). Vygotsky’s work on the Zone of Proximal Development (ZPD) and mediation provides a theoretical framework for proposing differentiation as a strategy. The data was gathered through an in-depth examination (using a combination of classroom observations, document analysis and teacher interviews) of mathematics teaching in Grade 1 in three schools in Grahamstown. My analysis was based on Vygotsky’s theories (the main tenets of which were the ZPD and scaffolding, as well as the role of socio-culture in learning), using Tomlinson’s (1999) differentiated instruction framework to provide structure to the study. The following themes emerged from the data: a focus on the teachers’ understandings of differentiation; the use of grouping as a superficial form of differentiation; a lack of teacher preparation and understanding in relation to task differentiation; and an underlying sense of ‘sameness’ in teachers’ understanding of their learners. In addition to the above, I did not observe evidence of real differentiation for high potential children and hope that this research contributes to extending teachers’ training (both academic and in-service) in this area, convincing teachers of the existence and importance of critical thinking abilities in our youngest learners, and initiating a move towards the drafting of Individual Education Plans for all our learners. During the period of my research I have been convinced that the use of differentiated instruction in classrooms is the way forward in educational thinking, particularly as it relates to the notion of inclusive learning. Clearly there are challenges to be addressed in terms of school timetables, curricula, teachers’ time frames and past education system inequalities such as we have here in South Africa.
- Full Text:
An evaluation of the postgraduate diploma in Enterprise Management at Rhodes University
- Authors: Earle, Nicola Lynne
- Date: 2012
- Subjects: Rhodes University -- Curricula Education, Higher -- Curricula -- South Africa -- Evaluation Business education -- Curricula -- South Africa -- Evaluation Business education -- Study and teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1180 , http://hdl.handle.net/10962/d1002797
- Description: This research is concerned with the development of entrepreneurship at higher education institutions (HEI). Entrepreneurship is very important in every country as there is a direct correlation between entrepreneurship development and economic growth (Hegarty, 2006). Entrepreneurship education is essential as it assists students who want to start up their own businesses by giving them the relevant skills and knowledge to have a successful business. The purpose of this research is to evaluate the Postgraduate Diploma in Enterprise Management (PDEM) within the Management Department at Rhodes University, Grahamstown. A qualitative approach was implemented which used an adapted version of the Context, Input, Process and Product Model (Stuffelbean, Mckee and Mckee, 2003). Data was collected in the form of interviews and focus group interviews. There were six lecturer interviews, one course coordinator interview and five past student interviews. There were two focus group interviews that took place; this was done so to gather data from seven current PDEM students. The data collected was then analysed through the use of qualitative data analysis techniques. These were sensing themes, constant comparison, recursiveness, inductive and deductive thinking and interpretation to generate meaning (Ruona 2005, cited in Swanson and Holton, 2005). The Management Department aims to equip students to think realistically in terms of starting their own business and to enhance the students’ knowledge and skills so that they are better able to find employment in the corporate and government sectors. The PDEM aims to be an action-learning course and to create an entrepreneurial environment which will encourage students to start up their own businesses. The role of the lecturers and the course coordinator is important as they need to ensure that there is a continuous transfer of knowledge to the students. Students are not expected to be specialists within each subject; however they need to have a basic grounding in order to run a business. Students felt that the Alpha Project was important and useful as it improved their confidence about starting a new business. An issue that was raised about the Alpha Project was that the separation of students into the Alpha Project groups was not executed well. The course was perceived to be disorganised however the students tended to enjoy it and felt that the Management Department was supportive of their businesses.
- Full Text:
- Authors: Earle, Nicola Lynne
- Date: 2012
- Subjects: Rhodes University -- Curricula Education, Higher -- Curricula -- South Africa -- Evaluation Business education -- Curricula -- South Africa -- Evaluation Business education -- Study and teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1180 , http://hdl.handle.net/10962/d1002797
- Description: This research is concerned with the development of entrepreneurship at higher education institutions (HEI). Entrepreneurship is very important in every country as there is a direct correlation between entrepreneurship development and economic growth (Hegarty, 2006). Entrepreneurship education is essential as it assists students who want to start up their own businesses by giving them the relevant skills and knowledge to have a successful business. The purpose of this research is to evaluate the Postgraduate Diploma in Enterprise Management (PDEM) within the Management Department at Rhodes University, Grahamstown. A qualitative approach was implemented which used an adapted version of the Context, Input, Process and Product Model (Stuffelbean, Mckee and Mckee, 2003). Data was collected in the form of interviews and focus group interviews. There were six lecturer interviews, one course coordinator interview and five past student interviews. There were two focus group interviews that took place; this was done so to gather data from seven current PDEM students. The data collected was then analysed through the use of qualitative data analysis techniques. These were sensing themes, constant comparison, recursiveness, inductive and deductive thinking and interpretation to generate meaning (Ruona 2005, cited in Swanson and Holton, 2005). The Management Department aims to equip students to think realistically in terms of starting their own business and to enhance the students’ knowledge and skills so that they are better able to find employment in the corporate and government sectors. The PDEM aims to be an action-learning course and to create an entrepreneurial environment which will encourage students to start up their own businesses. The role of the lecturers and the course coordinator is important as they need to ensure that there is a continuous transfer of knowledge to the students. Students are not expected to be specialists within each subject; however they need to have a basic grounding in order to run a business. Students felt that the Alpha Project was important and useful as it improved their confidence about starting a new business. An issue that was raised about the Alpha Project was that the separation of students into the Alpha Project groups was not executed well. The course was perceived to be disorganised however the students tended to enjoy it and felt that the Management Department was supportive of their businesses.
- Full Text:
An investigation into how cell phones can be used in the teaching of mathematics using VITALmaths video clips: a case study of 2 schools in Grahamstown, South Africa
- Authors: Ndafenongo, Gerhard
- Date: 2012
- Subjects: Mathematics -- Study and teaching (Secondary) -- South Africa -- Grahamstown Educational innovations -- South Africa -- Grahamstown Telecommunication in education -- South Africa -- Grahamstown Teaching -- Aids and devices -- South Africa -- Grahamstown Mathematics Software -- South Africa -- Grahamstown Mobile communication systems in education -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1596 , http://hdl.handle.net/10962/d1003478
- Description: Cell phones have become a ubiquitous part of daily life for both teachers and learners alike. The educational potential afforded by cell phones is diverse. The challenge for teachers is to capitalise on this ubiquity and make use of cell phones for educational purposes. This study investigates how cell phones can be used in the teaching of Mathematics using VITALmaths video clips. Five VITALmaths video clips were uploaded onto cell phones which were used in the classroom to explore the Theorem of Pythagoras in a visually appealing way that supported a conceptual understanding of the basis of the theorem. The study was conducted in two high schools in Grahamstown, South Africa. It involved two teachers from each school and a total number of 47 Grade 10 Mathematics students. The participating teachers were chosen from a group of Mathematics teachers taking part in the Mathematics Teacher Enrichment Programme (MTEP) of the FirstRand Foundation Mathematics Education Chair hosted by Rhodes University. This study is framed as a case study and is grounded within the interpretive paradigm. The study captures teachers’ and learners’ experiences in using cell phones as instructional aids within the pedagogical context of the classroom. This research suggests that cell phones can be a useful resource to support teaching and learning in the classroom, particularly in under-resourced schools. The use of VITALmaths video clips as mathematical content, and cell phones as a vehicle of delivery, enhanced active participation and concentration, sped up lessons, encouraged collaboration as well as interaction and hands-on exploration, and promoted both student autonomy as well as teacher enrichment.
- Full Text:
- Authors: Ndafenongo, Gerhard
- Date: 2012
- Subjects: Mathematics -- Study and teaching (Secondary) -- South Africa -- Grahamstown Educational innovations -- South Africa -- Grahamstown Telecommunication in education -- South Africa -- Grahamstown Teaching -- Aids and devices -- South Africa -- Grahamstown Mathematics Software -- South Africa -- Grahamstown Mobile communication systems in education -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1596 , http://hdl.handle.net/10962/d1003478
- Description: Cell phones have become a ubiquitous part of daily life for both teachers and learners alike. The educational potential afforded by cell phones is diverse. The challenge for teachers is to capitalise on this ubiquity and make use of cell phones for educational purposes. This study investigates how cell phones can be used in the teaching of Mathematics using VITALmaths video clips. Five VITALmaths video clips were uploaded onto cell phones which were used in the classroom to explore the Theorem of Pythagoras in a visually appealing way that supported a conceptual understanding of the basis of the theorem. The study was conducted in two high schools in Grahamstown, South Africa. It involved two teachers from each school and a total number of 47 Grade 10 Mathematics students. The participating teachers were chosen from a group of Mathematics teachers taking part in the Mathematics Teacher Enrichment Programme (MTEP) of the FirstRand Foundation Mathematics Education Chair hosted by Rhodes University. This study is framed as a case study and is grounded within the interpretive paradigm. The study captures teachers’ and learners’ experiences in using cell phones as instructional aids within the pedagogical context of the classroom. This research suggests that cell phones can be a useful resource to support teaching and learning in the classroom, particularly in under-resourced schools. The use of VITALmaths video clips as mathematical content, and cell phones as a vehicle of delivery, enhanced active participation and concentration, sped up lessons, encouraged collaboration as well as interaction and hands-on exploration, and promoted both student autonomy as well as teacher enrichment.
- Full Text:
The representation of women's reproductive rights in the American feminist blogosphere: an analysis of the debate around women's reproductive rights and abortion legislation in response to the reformation of the United States health care system in 2009/10
- Authors: Yelverton, Brittany
- Date: 2010
- Subjects: Abortion -- Law and legislation -- United States Reproductive rights -- Law and legislation -- United States Fertility -- Law and legislation -- United States Feminism Blogs -- United States Health care reform -- United States -- 21st century Women -- Blogs -- United States Social change -- United States Discourse analysis Feministing Jezebel
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3494 , http://hdl.handle.net/10962/d1002949
- Description: This study investigates the representation of women's reproductive rights in the feminist blogopshere during 2009/10 United States health care reform. Focusing on two purposively selected feminist blogsites - Feministing and Jezebel- it critically examines the discursive and rhetorical strategies employed by feminist bloggers to contest the erosion of women's reproductive rights as proposed in health care reform legislation. While the reformation of the U.S. health care system was a lengthy process, my analysis is confined to feminist blog posts published in November 2009, December 2009 and March 2010. These three months have been designated as they are roughly representative of three pivotal stages in health care reform: the drafting of the House of Representatives health care reform bill and Stupak Amendment in November 2009, the creation of the Senate health care bill inclusive of the Nelson compromise in December 2009, and the passage of the finalised health care reform bill, the Patient Protection and Affordable Care Act and supplementary executive order, in March 2010. This study is informed by feminist poststructuralist theory and Foucault's conceptions of discourse and power - an appropriate framework for identifying and analysing the unequal power relations that exist between men and women in patriarchal societies. Foucault conceives of discourse as both socially constituted and constitutive and contends that through the constitution of knowledge, discourses designate acceptable ways of talking, writing, and behaving, while simultaneously restricting and prohibiting alternatives, thereby granting power and authority to specific discourses. However, Foucault also stresses the multi-directionality of power and asserts that though hegemonic discourses are privileged over others, power lays in discursive practice at all social sites; hence the socially and politically transformative power of contesting discourses. Critical discourse analysis is informed by this critical theory of language and regards the use of language as a form of social practice located within its specific historical context. Therefore, it is through engaging in the struggle over meaning and producing different 'truths' through the reappropriation of language that the possibility of social change exists. Employing narrative, linguistic and rhetorical analysis, this study identifies the discursive strategies and tactics utilised by feminist bloggers to combat and contest anti-choice health care legislation. The study further seeks to determine how arguments supportive of women's reproductive rights are framed and how feminist discourses are privileged while patriarchal discourse is contested. Drawing on public sphere theory, I argue that the feminist blogosphere constitutes a counter-public which facili tates the articulation and circulation of marginalised and counter-discourses. I conclude this study by examining the feminist blogopshere's role in promoting political change and transformation through alternative representations of women and their reproductive rights.
- Full Text:
- Authors: Yelverton, Brittany
- Date: 2010
- Subjects: Abortion -- Law and legislation -- United States Reproductive rights -- Law and legislation -- United States Fertility -- Law and legislation -- United States Feminism Blogs -- United States Health care reform -- United States -- 21st century Women -- Blogs -- United States Social change -- United States Discourse analysis Feministing Jezebel
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3494 , http://hdl.handle.net/10962/d1002949
- Description: This study investigates the representation of women's reproductive rights in the feminist blogopshere during 2009/10 United States health care reform. Focusing on two purposively selected feminist blogsites - Feministing and Jezebel- it critically examines the discursive and rhetorical strategies employed by feminist bloggers to contest the erosion of women's reproductive rights as proposed in health care reform legislation. While the reformation of the U.S. health care system was a lengthy process, my analysis is confined to feminist blog posts published in November 2009, December 2009 and March 2010. These three months have been designated as they are roughly representative of three pivotal stages in health care reform: the drafting of the House of Representatives health care reform bill and Stupak Amendment in November 2009, the creation of the Senate health care bill inclusive of the Nelson compromise in December 2009, and the passage of the finalised health care reform bill, the Patient Protection and Affordable Care Act and supplementary executive order, in March 2010. This study is informed by feminist poststructuralist theory and Foucault's conceptions of discourse and power - an appropriate framework for identifying and analysing the unequal power relations that exist between men and women in patriarchal societies. Foucault conceives of discourse as both socially constituted and constitutive and contends that through the constitution of knowledge, discourses designate acceptable ways of talking, writing, and behaving, while simultaneously restricting and prohibiting alternatives, thereby granting power and authority to specific discourses. However, Foucault also stresses the multi-directionality of power and asserts that though hegemonic discourses are privileged over others, power lays in discursive practice at all social sites; hence the socially and politically transformative power of contesting discourses. Critical discourse analysis is informed by this critical theory of language and regards the use of language as a form of social practice located within its specific historical context. Therefore, it is through engaging in the struggle over meaning and producing different 'truths' through the reappropriation of language that the possibility of social change exists. Employing narrative, linguistic and rhetorical analysis, this study identifies the discursive strategies and tactics utilised by feminist bloggers to combat and contest anti-choice health care legislation. The study further seeks to determine how arguments supportive of women's reproductive rights are framed and how feminist discourses are privileged while patriarchal discourse is contested. Drawing on public sphere theory, I argue that the feminist blogosphere constitutes a counter-public which facili tates the articulation and circulation of marginalised and counter-discourses. I conclude this study by examining the feminist blogopshere's role in promoting political change and transformation through alternative representations of women and their reproductive rights.
- Full Text:
A resource-based learning approach to professional development: the case of the ACEE (Rhodes University Advanced Certificate in Environmental Education)
- Agria Russo, Vladimir Kiluange
- Authors: Agria Russo, Vladimir Kiluange
- Date: 2004
- Subjects: Rhodes University Advanced Certificate in Environmental Education Teaching -- Aids and devices -- South Africa Environmental education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1741 , http://hdl.handle.net/10962/d1003625
- Description: This interpretative case study derives and examines the characterising features of the resource-based learning approach used in the Rhodes University Advanced Certificate in Environmental Education (ACEE), particularly in Module 1 (Environment and Environmental Issues) and Module 3 (Contemporary Environmental Issues). The study explores processes of resource-based learning through the analysis of three individual case stories of participants’ experience in adaptive use of learning support materials in different work contexts. It discusses the relationship between thematic categories related to participants’ experience of assignment work, and course design and course implementation. This study indicates that resource-based learning processes in the ACEE involve curriculum deliberation and the use of resource packs in supporting participants’ practice. It also indicates that the ACEE’s practice-based orientation to workplace-based assignments plays an important role in supporting the adaptive use of learning support materials, encouraging lifelong learning and developing applied competence. It highlights the significance of reflexive narration of practice in improving course participants’ educational practice. A diagrammatic representation of the unfolding and intermeshed characterising features of resource-based learning is presented. The study argues that resource-based learning in the ACEE appears to create possibilities for the course participants to become scaffolders and co-constructors of their own learning. It notes that resource-based learning can enable course participants to take ownership of their educational and workplace needs, and to develop skills and competences necessary to respond to environmental issues and risks in southern Africa. This study examines the potential that the reflexive narration of practice has in supporting course participants to engage in better ways of doing things in their workplace-based contexts. This study provides some recommendations to enhance the Advanced Certificate in Environmental Education as well as some ‘fuzzy generalisations’ that might guide the Southern African Development Community (SADC) Regional Environmental Education Programme (REEP) in the development and adaptation of professional development courses in southern Africa.
- Full Text:
- Authors: Agria Russo, Vladimir Kiluange
- Date: 2004
- Subjects: Rhodes University Advanced Certificate in Environmental Education Teaching -- Aids and devices -- South Africa Environmental education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1741 , http://hdl.handle.net/10962/d1003625
- Description: This interpretative case study derives and examines the characterising features of the resource-based learning approach used in the Rhodes University Advanced Certificate in Environmental Education (ACEE), particularly in Module 1 (Environment and Environmental Issues) and Module 3 (Contemporary Environmental Issues). The study explores processes of resource-based learning through the analysis of three individual case stories of participants’ experience in adaptive use of learning support materials in different work contexts. It discusses the relationship between thematic categories related to participants’ experience of assignment work, and course design and course implementation. This study indicates that resource-based learning processes in the ACEE involve curriculum deliberation and the use of resource packs in supporting participants’ practice. It also indicates that the ACEE’s practice-based orientation to workplace-based assignments plays an important role in supporting the adaptive use of learning support materials, encouraging lifelong learning and developing applied competence. It highlights the significance of reflexive narration of practice in improving course participants’ educational practice. A diagrammatic representation of the unfolding and intermeshed characterising features of resource-based learning is presented. The study argues that resource-based learning in the ACEE appears to create possibilities for the course participants to become scaffolders and co-constructors of their own learning. It notes that resource-based learning can enable course participants to take ownership of their educational and workplace needs, and to develop skills and competences necessary to respond to environmental issues and risks in southern Africa. This study examines the potential that the reflexive narration of practice has in supporting course participants to engage in better ways of doing things in their workplace-based contexts. This study provides some recommendations to enhance the Advanced Certificate in Environmental Education as well as some ‘fuzzy generalisations’ that might guide the Southern African Development Community (SADC) Regional Environmental Education Programme (REEP) in the development and adaptation of professional development courses in southern Africa.
- Full Text:
Probing learners' conceptual understanding of oxidation and reduction (redox) reactions : a case study
- Authors: Addam, Billey Bright
- Date: 2004
- Subjects: Competency based education -- South Africa Oxidation-reduction reaction -- Study and teaching Science -- Study and teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1409 , http://hdl.handle.net/10962/d1002950
- Description: The new political dispensation in South Africa has seen a lot of changes taking place. The democratic wind, which has been blowing in all spheres of the political arena, could not leave out Education. This has led to the transformation in education and the revision of the curriculum guided by the Outcomes-Based Education philosophy (OBE). Thus, require education authorities as well as educators to look at education more comprehensively. The challenge posed to educators now is to develop tools and strategies that will make learning accessible to as many learners as possible and to teach for understanding and construction of knowledge. The principal objective of this study was to investigate the important role the learner's prior knowledge plays and the use of different tools and strategies in stimulating conceptual understanding and construction of knowledge of redox reactions. This was done using learners' own investigations, practical activities, teaching settings and a workshop. The findings show that the learners lacked organized and structured prior knowledge. Learners could not integrate prior experience with new experience. The main issue seems to be the failure of learners to relate classroom experience to everyday redox phenomena. Possible reasons are discussed with some implications for teaching redox. The study further postulates that to assist learners to develop conceptual understanding of redox reactions, different tools and strategies should be employed and teaching made relevant to real-life situations. In so doing, redox concepts would not be abstract to learners.
- Full Text:
- Authors: Addam, Billey Bright
- Date: 2004
- Subjects: Competency based education -- South Africa Oxidation-reduction reaction -- Study and teaching Science -- Study and teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1409 , http://hdl.handle.net/10962/d1002950
- Description: The new political dispensation in South Africa has seen a lot of changes taking place. The democratic wind, which has been blowing in all spheres of the political arena, could not leave out Education. This has led to the transformation in education and the revision of the curriculum guided by the Outcomes-Based Education philosophy (OBE). Thus, require education authorities as well as educators to look at education more comprehensively. The challenge posed to educators now is to develop tools and strategies that will make learning accessible to as many learners as possible and to teach for understanding and construction of knowledge. The principal objective of this study was to investigate the important role the learner's prior knowledge plays and the use of different tools and strategies in stimulating conceptual understanding and construction of knowledge of redox reactions. This was done using learners' own investigations, practical activities, teaching settings and a workshop. The findings show that the learners lacked organized and structured prior knowledge. Learners could not integrate prior experience with new experience. The main issue seems to be the failure of learners to relate classroom experience to everyday redox phenomena. Possible reasons are discussed with some implications for teaching redox. The study further postulates that to assist learners to develop conceptual understanding of redox reactions, different tools and strategies should be employed and teaching made relevant to real-life situations. In so doing, redox concepts would not be abstract to learners.
- Full Text:
The independent high rate algal pond as a unit operation in tertiary wastewater treatment
- Authors: Clark, Stewart James
- Date: 2002
- Subjects: Algae -- Biotechnology , Sewage -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4092 , http://hdl.handle.net/10962/d1007805
- Description: The development of the High Rate Algal Pond (HRAP) as an independent tertiary treatment unit operation for phosphate and nitrate removal is reported. A novel Integrated Algal Ponding System (lAPS) design is proposed for nutrient removal from the effluents of both a conventional domestic sewage treatment plant and from an Advanced Integrated Wastewater Ponding System (AIWPS). The viability of an independently operated HRAP has been identified and termed the Independent High Rate Algal Pond (l-HRAP). A 500 m² pilot 1- HRAP was operated in such a way as to facilitate the precipitation of calcium phosphate, known to be controlled by pH (greater than 9.4) and resulting in final phosphate levels of less than 1 mg.L⁻¹ as P0₄-P. The incorporation of the I-HRAP into a denitrification process was also investigated. Continuously fed column reactors, utilising algal biomass as a carbon source, showed that the heterotrophic bacterial community dominant in the anaerobic algal sludge were denitrifying the nitrate in the feed. It was demonstrated that as the cultures were stressed (using increased nitrate concentrations, anaerobiosis and light starvation) total polysaccharide (TPS) concentrations increased, with a notable increase 111 the exopolysaccharide (EPS) fraction. These experiments corroborated the hypothesis that harvested microalgal biomass can be manipulated to produce, and release, exopolymeric substances under stress conditions, and which may serve as carbon source for denitrification. In both batch flask studies and in laboratory-scale reactor systems, harvested microalgal biomass from an HRAP was shown to produce exopolymeric substances under stress conditions. Initial high loading-rates of greater than 20 mg.L⁻¹ NO₃-N resulted in double the amount of exopolysaccharide production than in flasks with initial low loading-rates (less than 5 mg.L⁻¹ NO₃-N). Making use of an upflow anaerobic sludge blanket-type degrading-bed reactor, and an anaerobic, flooded trickle filter (ANTRIC) receiving HRAP effluent, the relationship between denitrification and the changes in polysaccharide content was investigated. This phenomenon has considerable beneficial implications in biological wastewater treatment systems where high nitrate concentration in the final effluent is a potential mitigating factor. Identification of the heterotrophic bacteria active in the denitrification process was attempted. This study presents a first report on the development and operation of the I-HRAP and has been followed by a technical-scale pilot plant evaluation of the process in the tertiary treatment of domestic wastewaters.
- Full Text:
- Authors: Clark, Stewart James
- Date: 2002
- Subjects: Algae -- Biotechnology , Sewage -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4092 , http://hdl.handle.net/10962/d1007805
- Description: The development of the High Rate Algal Pond (HRAP) as an independent tertiary treatment unit operation for phosphate and nitrate removal is reported. A novel Integrated Algal Ponding System (lAPS) design is proposed for nutrient removal from the effluents of both a conventional domestic sewage treatment plant and from an Advanced Integrated Wastewater Ponding System (AIWPS). The viability of an independently operated HRAP has been identified and termed the Independent High Rate Algal Pond (l-HRAP). A 500 m² pilot 1- HRAP was operated in such a way as to facilitate the precipitation of calcium phosphate, known to be controlled by pH (greater than 9.4) and resulting in final phosphate levels of less than 1 mg.L⁻¹ as P0₄-P. The incorporation of the I-HRAP into a denitrification process was also investigated. Continuously fed column reactors, utilising algal biomass as a carbon source, showed that the heterotrophic bacterial community dominant in the anaerobic algal sludge were denitrifying the nitrate in the feed. It was demonstrated that as the cultures were stressed (using increased nitrate concentrations, anaerobiosis and light starvation) total polysaccharide (TPS) concentrations increased, with a notable increase 111 the exopolysaccharide (EPS) fraction. These experiments corroborated the hypothesis that harvested microalgal biomass can be manipulated to produce, and release, exopolymeric substances under stress conditions, and which may serve as carbon source for denitrification. In both batch flask studies and in laboratory-scale reactor systems, harvested microalgal biomass from an HRAP was shown to produce exopolymeric substances under stress conditions. Initial high loading-rates of greater than 20 mg.L⁻¹ NO₃-N resulted in double the amount of exopolysaccharide production than in flasks with initial low loading-rates (less than 5 mg.L⁻¹ NO₃-N). Making use of an upflow anaerobic sludge blanket-type degrading-bed reactor, and an anaerobic, flooded trickle filter (ANTRIC) receiving HRAP effluent, the relationship between denitrification and the changes in polysaccharide content was investigated. This phenomenon has considerable beneficial implications in biological wastewater treatment systems where high nitrate concentration in the final effluent is a potential mitigating factor. Identification of the heterotrophic bacteria active in the denitrification process was attempted. This study presents a first report on the development and operation of the I-HRAP and has been followed by a technical-scale pilot plant evaluation of the process in the tertiary treatment of domestic wastewaters.
- Full Text:
Towards the performer-creator in contemporary mime, with specific reference to the physical theatre of Andrew Buckland, 1988-2000
- Authors: Murray, Robert Ian
- Date: 2002
- Subjects: Buckland, Andrew , Mime , Mimes -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2158 , http://hdl.handle.net/10962/d1007720
- Description: Part one of this thesis investigates the conceptualisation of the performer-creator and its relevance in late twentieth century physical performance by examining some of the theoretical, but mainly artistic, traditions that suggest a movement towards this. Chapter one tackles the question of definition, linking mime within a wider physical theatre phenomenon. Chapter two looks at the importance of mime training for contemporary performance. This requires a focus on selected theatre practitioners who have significantly advanced the development of mime training and performance during the twentieth century. Chapter three examines the issue of silence in mime and questions a potential liberation of the word and language in contemporary performance and consequently how this affects the role of the performer, particularly in South Africa. Chapter four investigates the figure of the theatrical clown and how this late twentieth century development is playing an increasingly important role in contemporary performance. Chapter five then wraps up part one by pulling the preceding chapters together and thereby providing a working conceptualisation of the performer-creator, locating it within an overall appreciation of contemporary mime. Part two then tests the notion of the performer-creator by focussing on a case study through the investigation of Andrew Buckland to develop this idea. Andrew Buckland, and his work under the ethos of Mouthpeace from 1988-2000, provides a clear and unique example of this movement in contemporary South African performance. Trained as an actor and in classical illusion-based mime technique, as well as many dance forms such as ballet, contemporary and jazz, he has virtually single-handedly created and shaped a particular performance trend that is in line with contemporary international trends but retains a distinctive South African flavour. There is no space to attempt a definitive or exhaustive examination of his works, and nor is the intent to do so; rather, the aim is to draw from his work their essences that reveal his development as an artist: as both a creator and a performer.
- Full Text:
- Authors: Murray, Robert Ian
- Date: 2002
- Subjects: Buckland, Andrew , Mime , Mimes -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2158 , http://hdl.handle.net/10962/d1007720
- Description: Part one of this thesis investigates the conceptualisation of the performer-creator and its relevance in late twentieth century physical performance by examining some of the theoretical, but mainly artistic, traditions that suggest a movement towards this. Chapter one tackles the question of definition, linking mime within a wider physical theatre phenomenon. Chapter two looks at the importance of mime training for contemporary performance. This requires a focus on selected theatre practitioners who have significantly advanced the development of mime training and performance during the twentieth century. Chapter three examines the issue of silence in mime and questions a potential liberation of the word and language in contemporary performance and consequently how this affects the role of the performer, particularly in South Africa. Chapter four investigates the figure of the theatrical clown and how this late twentieth century development is playing an increasingly important role in contemporary performance. Chapter five then wraps up part one by pulling the preceding chapters together and thereby providing a working conceptualisation of the performer-creator, locating it within an overall appreciation of contemporary mime. Part two then tests the notion of the performer-creator by focussing on a case study through the investigation of Andrew Buckland to develop this idea. Andrew Buckland, and his work under the ethos of Mouthpeace from 1988-2000, provides a clear and unique example of this movement in contemporary South African performance. Trained as an actor and in classical illusion-based mime technique, as well as many dance forms such as ballet, contemporary and jazz, he has virtually single-handedly created and shaped a particular performance trend that is in line with contemporary international trends but retains a distinctive South African flavour. There is no space to attempt a definitive or exhaustive examination of his works, and nor is the intent to do so; rather, the aim is to draw from his work their essences that reveal his development as an artist: as both a creator and a performer.
- Full Text:
The construction of 'farm killings' in the Eastern Province Herald: an ideological analysis of the Herald's farm killings' disclosure, August 1998
- Authors: Jacobs, Luzuko
- Date: 2001
- Subjects: Farm killings -- South Africa -- Eastern Cape Murder -- South Africa -- Eastern Cape Eastern Province Herald (Newspaper)
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3436 , http://hdl.handle.net/10962/d1002890
- Description: This study examines the ideological inflection of the ‘farm killings’ discourse in the Eastern Province Herald articles published in August 1998. ‘Farm killings’ is a media frame which was applied to a spate of killings of people on the country’s farms since 1994. Heightened and sustained media attention on the ‘farm killings’ has lifted the phenomenon from the other ‘run-of-the-mill’ murder crimes, and located it firmly as a matter of public concern and a subject of a broad political and economic debate. In this study I investigate the media coverage of the ‘farm killings’ within the context of these debates. The cultural studies approach to the study of the media provides a fruitful theoretical framework within which this study is located. The ideological examination of the articles is done using the critical linguistics method - a brand of reflexive, interpretative style of analysis which enables a sustained examination of media texts within their social, cultural and historical context. This study’s conclusions pose a challenge to the ‘Fourth Estate’ role often claimed for the media. In particular, it denies that the Herald objectively, fairly and truthfully reflected the experience on the farms during the period of this study. Its main finding is that the newspaper instead, constructed a particular understanding of the killings characterised by subtle racism, bias and partiality.
- Full Text:
- Authors: Jacobs, Luzuko
- Date: 2001
- Subjects: Farm killings -- South Africa -- Eastern Cape Murder -- South Africa -- Eastern Cape Eastern Province Herald (Newspaper)
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3436 , http://hdl.handle.net/10962/d1002890
- Description: This study examines the ideological inflection of the ‘farm killings’ discourse in the Eastern Province Herald articles published in August 1998. ‘Farm killings’ is a media frame which was applied to a spate of killings of people on the country’s farms since 1994. Heightened and sustained media attention on the ‘farm killings’ has lifted the phenomenon from the other ‘run-of-the-mill’ murder crimes, and located it firmly as a matter of public concern and a subject of a broad political and economic debate. In this study I investigate the media coverage of the ‘farm killings’ within the context of these debates. The cultural studies approach to the study of the media provides a fruitful theoretical framework within which this study is located. The ideological examination of the articles is done using the critical linguistics method - a brand of reflexive, interpretative style of analysis which enables a sustained examination of media texts within their social, cultural and historical context. This study’s conclusions pose a challenge to the ‘Fourth Estate’ role often claimed for the media. In particular, it denies that the Herald objectively, fairly and truthfully reflected the experience on the farms during the period of this study. Its main finding is that the newspaper instead, constructed a particular understanding of the killings characterised by subtle racism, bias and partiality.
- Full Text:
Aspects of the ecology and reproductive biology of the limpet, Helcion pruinosus (Gastropoda : prosobranchia)
- Authors: Henninger, Tony Oskar
- Date: 2000
- Subjects: Prosobranchia , Limpets -- Reproduction , Limpets -- Ecology , Prosobranchia -- Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5641 , http://hdl.handle.net/10962/d1005323 , Prosobranchia , Limpets -- Reproduction , Limpets -- Ecology , Prosobranchia -- Ecology
- Description: Helcion pruinosus, the rayed limpet, is found in the midshore region of the intertidal zone, (i.e. the Balanoid zone) of rocky shores, from Saldanha Bay to Sodwana Bay along the coast of South Africa. At Gonubie (32°57'S/25°01'E) this species of limpet was found under boulders, (when not feeding), and could reach average densities of 85/ m². The limpets prefer smooth boulders, avoiding those encrusted by coralline algae or boulders with a rough texture. There was no habitat segregation between adult and juvenile H. pruinosus, i.e. there was no sign of up-shore migration by larger individuals. Males out-numbered females by, on average 1.4 : 1, which was a similar sex ratio to that of the congeneric species, H. pectunculus (Gray, 996). Unlike H. pectunculus, there were no differences in shell lengths between males and females (p = 0.946 at Gonubie, south-east coast and p = 0.961 at Kommetjie, south-west coast; t-test). Shell height could also not be used as a criterion to differentiate between the sexes. The average maximum shell length of H. pruinosus at Gonubie and Kommetjie was 25 mm, but the maximum shell lengths found were 30 mm, (one individual in each case), on both the southeast coast and west coast. Growth occurred most rapidly in the first year of life, with individuals reaching 15 mm after 1 year. In the second year limpet growth slowed to only 7 mm. Sexual maturity was reached at a shell length of between 11 to 14 mm (at an age of 8 months to 1 year). The life-span of H. pruinosus was determined at 2.55 years on the south-east coast and 2.9 years on the south-west coast. Micro-growth bands were produced tidally. Growth occurred allometrically, i.e. shell length increased at a faster rate than shell height. The limpets foraged during low tide, at night, presumably feeding on epilithic algae on the boulders. A second smaller peak of limpet activity was often recorded during the day, when low tide coincided with dawn). More limpets (up to ten times more) were active at spring tides compared to neap tides. Limpet activity was greatest during the spring tides of autumn. During all seasons limpet activity peaked 30 minutes before low water, after which numbers decreased rapidly. All limpets had retreated beneath the boulders before being covered by the flooding tide. It was concluded that the limpets were responding to both endogenous and exogenous cues, but the actual stimulus for retreat could not be determined. The limpets did not return to a fixed scar nor did they return rigidly to a home site. H. pruinosus was found to be gonochoristic. Sexes could be separated, on dissection, according to the colour of their gonads (males had white gonads, whilst that of the females was olive-green). Gonads were present throughout the year in most individuals, i.e. totally spent animals were never observed. Reproductive seasonality was similar in west coast and south-east coast animals. The gonad indices of the west coast limpets were higher, (maximum of 35%), compared to that on the southeast coast, (25%). The animals were probably trickle spawners, with some individuals liberating gametes throughout the year. There was however synchrony in gametogenesis between male and female limpets on both the west coast and south-east coast lines. Gonad indices peaked in the summer months (October to December) with a second minor peak in April/May. These peaks occurred before the release of the gametes in spawning events. The gonad index was lowest in winter, (July). The ovaries were full of mature eggs (oocytes having a diameter of 200 to 250 ~) prior to spawning. The acinal wall thickness had been decreasing prior to spawning. After spawning there was an increase in previtellogenic eggs « 100 μm) in females, and an increase in the acinal wall thickness to indicate spermatogenesis. The two populations are subjected to different environmental conditions and the actual cue for stimulating the release of gametes could not be determined. Finally, a table of differences between H pruinosus and its sister species, H pectunculus was created to show the life-style of H pruinosus.
- Full Text:
- Authors: Henninger, Tony Oskar
- Date: 2000
- Subjects: Prosobranchia , Limpets -- Reproduction , Limpets -- Ecology , Prosobranchia -- Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5641 , http://hdl.handle.net/10962/d1005323 , Prosobranchia , Limpets -- Reproduction , Limpets -- Ecology , Prosobranchia -- Ecology
- Description: Helcion pruinosus, the rayed limpet, is found in the midshore region of the intertidal zone, (i.e. the Balanoid zone) of rocky shores, from Saldanha Bay to Sodwana Bay along the coast of South Africa. At Gonubie (32°57'S/25°01'E) this species of limpet was found under boulders, (when not feeding), and could reach average densities of 85/ m². The limpets prefer smooth boulders, avoiding those encrusted by coralline algae or boulders with a rough texture. There was no habitat segregation between adult and juvenile H. pruinosus, i.e. there was no sign of up-shore migration by larger individuals. Males out-numbered females by, on average 1.4 : 1, which was a similar sex ratio to that of the congeneric species, H. pectunculus (Gray, 996). Unlike H. pectunculus, there were no differences in shell lengths between males and females (p = 0.946 at Gonubie, south-east coast and p = 0.961 at Kommetjie, south-west coast; t-test). Shell height could also not be used as a criterion to differentiate between the sexes. The average maximum shell length of H. pruinosus at Gonubie and Kommetjie was 25 mm, but the maximum shell lengths found were 30 mm, (one individual in each case), on both the southeast coast and west coast. Growth occurred most rapidly in the first year of life, with individuals reaching 15 mm after 1 year. In the second year limpet growth slowed to only 7 mm. Sexual maturity was reached at a shell length of between 11 to 14 mm (at an age of 8 months to 1 year). The life-span of H. pruinosus was determined at 2.55 years on the south-east coast and 2.9 years on the south-west coast. Micro-growth bands were produced tidally. Growth occurred allometrically, i.e. shell length increased at a faster rate than shell height. The limpets foraged during low tide, at night, presumably feeding on epilithic algae on the boulders. A second smaller peak of limpet activity was often recorded during the day, when low tide coincided with dawn). More limpets (up to ten times more) were active at spring tides compared to neap tides. Limpet activity was greatest during the spring tides of autumn. During all seasons limpet activity peaked 30 minutes before low water, after which numbers decreased rapidly. All limpets had retreated beneath the boulders before being covered by the flooding tide. It was concluded that the limpets were responding to both endogenous and exogenous cues, but the actual stimulus for retreat could not be determined. The limpets did not return to a fixed scar nor did they return rigidly to a home site. H. pruinosus was found to be gonochoristic. Sexes could be separated, on dissection, according to the colour of their gonads (males had white gonads, whilst that of the females was olive-green). Gonads were present throughout the year in most individuals, i.e. totally spent animals were never observed. Reproductive seasonality was similar in west coast and south-east coast animals. The gonad indices of the west coast limpets were higher, (maximum of 35%), compared to that on the southeast coast, (25%). The animals were probably trickle spawners, with some individuals liberating gametes throughout the year. There was however synchrony in gametogenesis between male and female limpets on both the west coast and south-east coast lines. Gonad indices peaked in the summer months (October to December) with a second minor peak in April/May. These peaks occurred before the release of the gametes in spawning events. The gonad index was lowest in winter, (July). The ovaries were full of mature eggs (oocytes having a diameter of 200 to 250 ~) prior to spawning. The acinal wall thickness had been decreasing prior to spawning. After spawning there was an increase in previtellogenic eggs « 100 μm) in females, and an increase in the acinal wall thickness to indicate spermatogenesis. The two populations are subjected to different environmental conditions and the actual cue for stimulating the release of gametes could not be determined. Finally, a table of differences between H pruinosus and its sister species, H pectunculus was created to show the life-style of H pruinosus.
- Full Text:
The representation of "South Africanness" in the locally produced television production, Generations
- Authors: Dentlinger, Lindsay
- Date: 2000
- Subjects: Television soap operas -- South Africa , National characteristics, South African, In Literature
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3425 , http://hdl.handle.net/10962/d1002878 , Television soap operas -- South Africa , National characteristics, South African, In Literature
- Description: The aim of this study is to analyse selected episodes of the locally produced television programme Generations, in order to identify specific ways in which the programme seeks to forge a South African identity, and in so doing, 'flag' our nationhood as South Africans. These elements of 'South Africanness' are broadly defined as connections to a South African way of life, context, values and experiences. Generations is a programme produced under South African broadcasting local content provisions. These provisions arise out of the need, inter alia, to reflect the identity and multi-cultural nature of South Africa in order to foster 'national identity' and 'national culture'. These elements of 'South Africanness' are extracted through a genre and ideological analysis of selected sample episodes, taking into consideration the theoretical frameworks of the politics of representation and identity. The production context of, and representations made, in Generations, are found to be situated largely within the context of the South African discourses of the ‘rainbow nation', 'African renaissance' and 'black economic empowerment'. The analysis concludes that through the various categories of representations of 'South Africanness' in the selected episodes of Generations, specific instances of identity, that of national culture and national identity are formed.
- Full Text:
The representation of "South Africanness" in the locally produced television production, Generations
- Authors: Dentlinger, Lindsay
- Date: 2000
- Subjects: Television soap operas -- South Africa , National characteristics, South African, In Literature
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3425 , http://hdl.handle.net/10962/d1002878 , Television soap operas -- South Africa , National characteristics, South African, In Literature
- Description: The aim of this study is to analyse selected episodes of the locally produced television programme Generations, in order to identify specific ways in which the programme seeks to forge a South African identity, and in so doing, 'flag' our nationhood as South Africans. These elements of 'South Africanness' are broadly defined as connections to a South African way of life, context, values and experiences. Generations is a programme produced under South African broadcasting local content provisions. These provisions arise out of the need, inter alia, to reflect the identity and multi-cultural nature of South Africa in order to foster 'national identity' and 'national culture'. These elements of 'South Africanness' are extracted through a genre and ideological analysis of selected sample episodes, taking into consideration the theoretical frameworks of the politics of representation and identity. The production context of, and representations made, in Generations, are found to be situated largely within the context of the South African discourses of the ‘rainbow nation', 'African renaissance' and 'black economic empowerment'. The analysis concludes that through the various categories of representations of 'South Africanness' in the selected episodes of Generations, specific instances of identity, that of national culture and national identity are formed.
- Full Text:
Environmental and socio-economic effects associated with the planting of Atriplex nummularia Lindl. (Oldman saltbush) in the Karoo
- Authors: Hobson, Colin Desmond
- Date: 1991
- Subjects: Botany, Economic Plant introduction -- South Africa -- Karoo Plants, Cultivated
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:4794 , http://hdl.handle.net/10962/d1001894
- Description: This study examines the environmental and socio-economic effects associated with the planting of Atriplex nummularia Lindl. (Oldman saltbush) in the karoo. This is the first study of its kind on oldman saltbush and serves as an important scoping exercise in assessing the impact of saltbush on its surrounds and in identifying additional aspects which require investigation. The environmental parameters investigated include microclimatic effects, soil induced changes, salinity effects on the germination of selected karoo species and compositional changes in the indigenous plant community within a saltbush plantation. When compared to indigenous karoo plant species oldman saltbush is found to ameliorate soil temperatures and increase surface soil salinity (specifically sodium chloride), on an individual plant basis. Salinity is shown to have a differential effect on the germination of selected karoo shrubs. The indigenous plant community within a forty year old saltbush plantation is impoverished with both density of individuals and species richness being markedly reduced. Saltbush is identified as an unsuitable nurse plant for the majority of karoo shrubs. Farm size in relation to both actual and intended area established to saltbush is considered. The area of saltbush already established in the karoo is considered too insignificant to have any wide socio-economic impact. Farmers who intend planting large areas of their farms to saltbush are in the minority. It is those farmers who already have some saltbush planted, who intend planting more. Ecologically based management guidelines are presented, suggesting practices which minimize the detrimental effects of saltbush on soil salinity and the indigenous plant community. These guidelines are practical and in keeping with the overall objectives of optimum resource utilisation and the national grazing strategy for South Africa.
- Full Text:
- Authors: Hobson, Colin Desmond
- Date: 1991
- Subjects: Botany, Economic Plant introduction -- South Africa -- Karoo Plants, Cultivated
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:4794 , http://hdl.handle.net/10962/d1001894
- Description: This study examines the environmental and socio-economic effects associated with the planting of Atriplex nummularia Lindl. (Oldman saltbush) in the karoo. This is the first study of its kind on oldman saltbush and serves as an important scoping exercise in assessing the impact of saltbush on its surrounds and in identifying additional aspects which require investigation. The environmental parameters investigated include microclimatic effects, soil induced changes, salinity effects on the germination of selected karoo species and compositional changes in the indigenous plant community within a saltbush plantation. When compared to indigenous karoo plant species oldman saltbush is found to ameliorate soil temperatures and increase surface soil salinity (specifically sodium chloride), on an individual plant basis. Salinity is shown to have a differential effect on the germination of selected karoo shrubs. The indigenous plant community within a forty year old saltbush plantation is impoverished with both density of individuals and species richness being markedly reduced. Saltbush is identified as an unsuitable nurse plant for the majority of karoo shrubs. Farm size in relation to both actual and intended area established to saltbush is considered. The area of saltbush already established in the karoo is considered too insignificant to have any wide socio-economic impact. Farmers who intend planting large areas of their farms to saltbush are in the minority. It is those farmers who already have some saltbush planted, who intend planting more. Ecologically based management guidelines are presented, suggesting practices which minimize the detrimental effects of saltbush on soil salinity and the indigenous plant community. These guidelines are practical and in keeping with the overall objectives of optimum resource utilisation and the national grazing strategy for South Africa.
- Full Text:
Environmental and socio-economic effects associated with the planting of Atriplex nummularia Lindl. (Oldman saltbush) in the Karoo
- Authors: Hobson, Colin Desmond
- Date: 1991
- Subjects: Botany, Economic Plant introduction -- South Africa -- Karoo Plants, Cultivated
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:4175 , http://hdl.handle.net/10962/d1002023
- Description: This study examines the environmental and socio-economic effects associated with the planting of Atriplex nummularia Lindl. (Oldman saltbush) in the karoo. This is the first study of its kind on oldman saltbush and serves as an important scoping exercise in assessing the impact of saltbush on its surrounds and in identifying additional aspects which require investigation. The environmental parameters investigated include microclimatic effects, soil induced changes, salinity effects on the germination of selected karoo species and compositional changes in the indigenous plant community within a saltbush plantation. When compared to indigenous karoo plant species oldman saltbush is found to ameliorate soil temperatures and increase surface soil salinity (specifically sodium chloride), on an individual plant basis. Salinity is shown to have a differential effect on the germination of selected karoo shrubs. The indigenous plant community within a forty year old saltbush plantation is impoverished with both density of individuals and species richness being markedly reduced. Saltbush is identified as an unsuitable nurse plant for the majority of karoo shrubs. Farm size in relation to both actual and intended area established to saltbush is considered. The area of saltbush already established in the karoo is considered too insignificant to have any wide socio-economic impact. Farmers who intend planting large areas of their farms to saltbush are in the minority. It is those farmers who already have some saltbush planted, who intend planting more. Ecologically based management guidelines are presented, suggesting practices which minimize the detrimental effects of saltbush on soil salinity and the indigenous plant community. These guidelines are practical and in keeping with the overall objectives of optimum resource utilisation and the national grazing strategy for South Africa.
- Full Text:
- Authors: Hobson, Colin Desmond
- Date: 1991
- Subjects: Botany, Economic Plant introduction -- South Africa -- Karoo Plants, Cultivated
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: vital:4175 , http://hdl.handle.net/10962/d1002023
- Description: This study examines the environmental and socio-economic effects associated with the planting of Atriplex nummularia Lindl. (Oldman saltbush) in the karoo. This is the first study of its kind on oldman saltbush and serves as an important scoping exercise in assessing the impact of saltbush on its surrounds and in identifying additional aspects which require investigation. The environmental parameters investigated include microclimatic effects, soil induced changes, salinity effects on the germination of selected karoo species and compositional changes in the indigenous plant community within a saltbush plantation. When compared to indigenous karoo plant species oldman saltbush is found to ameliorate soil temperatures and increase surface soil salinity (specifically sodium chloride), on an individual plant basis. Salinity is shown to have a differential effect on the germination of selected karoo shrubs. The indigenous plant community within a forty year old saltbush plantation is impoverished with both density of individuals and species richness being markedly reduced. Saltbush is identified as an unsuitable nurse plant for the majority of karoo shrubs. Farm size in relation to both actual and intended area established to saltbush is considered. The area of saltbush already established in the karoo is considered too insignificant to have any wide socio-economic impact. Farmers who intend planting large areas of their farms to saltbush are in the minority. It is those farmers who already have some saltbush planted, who intend planting more. Ecologically based management guidelines are presented, suggesting practices which minimize the detrimental effects of saltbush on soil salinity and the indigenous plant community. These guidelines are practical and in keeping with the overall objectives of optimum resource utilisation and the national grazing strategy for South Africa.
- Full Text:
The pineal gland as a model to elucidate the primary mode of action of sympathoactive agents
- Authors: Welman, Alan David
- Date: 1991
- Subjects: Pineal gland , Cythochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3876 , http://hdl.handle.net/10962/d1001610
- Description: An attempt was made to use the pineal gland as a model for the study of the primary mode of action of sympathoactive agents. Two drugs were investigated, viz. alpha-methyldopa and ephedrine whose mode of action is not entirely clear. Organ cultures of pineal glands from rats treated chronically with alpha-methyldopa showed enhanced conversion of radioactive serotonin to melatonin (aMT) , as well as its precursor Nacetylserotonin (aHT). This treatment was also found to raise Nacetyltransferase (NAT) activity. These increases associated with alpha-methyldopa treatment were further enhanced by the beta-adrenergic agonist, isoproterenol, suggesting a supersensitivity-type effect occurring at the level of the beta-receptor. A subsequent binding study, however, showed a decrease in beta-receptor binding with exposure to alpha-methyldopa, providing mitigating evidence against the occurrence of a supersensitivity phenomenon. It is possible that a metabolite of alpha-methyldopa acts as an alpha 1 and beta-adrenergic agonist, resulting in greater melatonin (aMT) and N-acetylserotonin (aHT) synthesis than by a beta-adrenergic agonist, isoproterenol. Combined treatment of pineals with alpha-methyldopa and an alphareceptor blocker, phentolamine, resulted in melatonin (aMT) , Nacetylserotonin (aHT) , and N-acetyltransferase (NAT) activity levels which were lower than those obtained with alpha-methyldopa treatment alone, thus confirming the alpha-adrenergic activity of the metabolite of alpha-methyldopa. Additional pineal metabolites were isolated and measured simultaneously in the organ culture experiments. Organ cultures of rat pineal glands treated with ephedrine showed raised levels of melatonin (aMT) and N-acetylserotonin (aHT). Treatment with ephedrine also produced raised N-acetyltransferase activity. A further enhancement of these parameters was induced by norepinephrine, suggesting a supersensitivity-type effect occurring at the level of the beta-adrenergic receptor. Rats were treated with reserpine (a norepinephrine depleter) and the pineals exposed to ephedrine. Endogenous norepinephrine normally released by the action of ephedrine was thus absent, and under these conditions, levels of melatonin (aMT) and N-acetylserotonin (aHT) were reduced. N-acetyltransferase (NAT) activity was also reduced, but maintained levels pointing to substantial adrenergic activity of ephedrine as well as norepinephrine released by virtue of the drug's action. A subsequent binding study showed a decrease in beta-adrenergic receptor binding with exposure to ephedrine and a further decrease in ephedrine treated pineals from reserpine treated rats, thus ruling out the occurrence of a supersensitivity phenomenon. It is possible that both ephedrine and released norepinephrine have alpha- and beta-receptor activity. Additional pineal metabolites were isolated and measured in the organ culture experiments. A 16-hour time profile of the production of melatonin (aMT) and N-acetylserotonin (aHT) with norepinephrine and ephedrine treatment provided useful information regarding the course of action of the two agents. A pineal cell-culture system was developed and exposed to ephedrine and norepinephrine. N-acetyltransferase (NAT) activity levels measured after exposure to these agents were raised, confirming the adrenergic activity of both in the model. Finally, an HPLC system coupled to a UV detector was used in an attempt to measure melatonin (aMT) extracted from pineal organ culture media. The results showed that melatonin could be measured by this method, however, a more sensitive detection system was recommended for future work.
- Full Text:
- Authors: Welman, Alan David
- Date: 1991
- Subjects: Pineal gland , Cythochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3876 , http://hdl.handle.net/10962/d1001610
- Description: An attempt was made to use the pineal gland as a model for the study of the primary mode of action of sympathoactive agents. Two drugs were investigated, viz. alpha-methyldopa and ephedrine whose mode of action is not entirely clear. Organ cultures of pineal glands from rats treated chronically with alpha-methyldopa showed enhanced conversion of radioactive serotonin to melatonin (aMT) , as well as its precursor Nacetylserotonin (aHT). This treatment was also found to raise Nacetyltransferase (NAT) activity. These increases associated with alpha-methyldopa treatment were further enhanced by the beta-adrenergic agonist, isoproterenol, suggesting a supersensitivity-type effect occurring at the level of the beta-receptor. A subsequent binding study, however, showed a decrease in beta-receptor binding with exposure to alpha-methyldopa, providing mitigating evidence against the occurrence of a supersensitivity phenomenon. It is possible that a metabolite of alpha-methyldopa acts as an alpha 1 and beta-adrenergic agonist, resulting in greater melatonin (aMT) and N-acetylserotonin (aHT) synthesis than by a beta-adrenergic agonist, isoproterenol. Combined treatment of pineals with alpha-methyldopa and an alphareceptor blocker, phentolamine, resulted in melatonin (aMT) , Nacetylserotonin (aHT) , and N-acetyltransferase (NAT) activity levels which were lower than those obtained with alpha-methyldopa treatment alone, thus confirming the alpha-adrenergic activity of the metabolite of alpha-methyldopa. Additional pineal metabolites were isolated and measured simultaneously in the organ culture experiments. Organ cultures of rat pineal glands treated with ephedrine showed raised levels of melatonin (aMT) and N-acetylserotonin (aHT). Treatment with ephedrine also produced raised N-acetyltransferase activity. A further enhancement of these parameters was induced by norepinephrine, suggesting a supersensitivity-type effect occurring at the level of the beta-adrenergic receptor. Rats were treated with reserpine (a norepinephrine depleter) and the pineals exposed to ephedrine. Endogenous norepinephrine normally released by the action of ephedrine was thus absent, and under these conditions, levels of melatonin (aMT) and N-acetylserotonin (aHT) were reduced. N-acetyltransferase (NAT) activity was also reduced, but maintained levels pointing to substantial adrenergic activity of ephedrine as well as norepinephrine released by virtue of the drug's action. A subsequent binding study showed a decrease in beta-adrenergic receptor binding with exposure to ephedrine and a further decrease in ephedrine treated pineals from reserpine treated rats, thus ruling out the occurrence of a supersensitivity phenomenon. It is possible that both ephedrine and released norepinephrine have alpha- and beta-receptor activity. Additional pineal metabolites were isolated and measured in the organ culture experiments. A 16-hour time profile of the production of melatonin (aMT) and N-acetylserotonin (aHT) with norepinephrine and ephedrine treatment provided useful information regarding the course of action of the two agents. A pineal cell-culture system was developed and exposed to ephedrine and norepinephrine. N-acetyltransferase (NAT) activity levels measured after exposure to these agents were raised, confirming the adrenergic activity of both in the model. Finally, an HPLC system coupled to a UV detector was used in an attempt to measure melatonin (aMT) extracted from pineal organ culture media. The results showed that melatonin could be measured by this method, however, a more sensitive detection system was recommended for future work.
- Full Text:
The pineal gland as a model to elucidate the primary mode of action of sympathoactive agents
- Authors: Welman, Alan David
- Date: 1991
- Subjects: Pineal gland , Cythochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4279 , http://hdl.handle.net/10962/d1002005 , Pineal gland
- Description: An attempt was made to use the pineal gland as a model for the study of the primary mode of action of sympathoactive agents. Two drugs were investigated, viz. alpha-methyldopa and ephedrine whose mode of action is not entirely clear. Organ cultures of pineal glands from rats treated chronically with alpha-methyldopa showed enhanced conversion of radioactive serotonin to melatonin (aMT) , as well as its precursor Nacetylserotonin (aHT). This treatment was also found to raise Nacetyltransferase (NAT) activity. These increases associated with alpha-methyldopa treatment were further enhanced by the beta-adrenergic agonist, isoproterenol, suggesting a supersensitivity-type effect occurring at the level of the beta-receptor. A subsequent binding study, however, showed a decrease in beta-receptor binding with exposure to alpha-methyldopa, providing mitigating evidence against the occurrence of a supersensitivity phenomenon. It is possible that a metabolite of alpha-methyldopa acts as an alpha 1 and beta-adrenergic agonist, resulting in greater melatonin (aMT) and N-acetylserotonin (aHT) synthesis than by a beta-adrenergic agonist, isoproterenol. Combined treatment of pineals with alpha-methyldopa and an alphareceptor blocker, phentolamine, resulted in melatonin (aMT) , Nacetylserotonin (aHT) , and N-acetyltransferase (NAT) activity levels which were lower than those obtained with alpha-methyldopa treatment alone, thus confirming the alpha-adrenergic activity of the metabolite of alpha-methyldopa. Additional pineal metabolites were isolated and measured simultaneously in the organ culture experiments. Organ cultures of rat pineal glands treated with ephedrine showed raised levels of melatonin (aMT) and N-acetylserotonin (aHT). Treatment with ephedrine also produced raised N-acetyltransferase activity. A further enhancement of these parameters was induced by norepinephrine, suggesting a supersensitivity-type effect occurring at the level of the beta-adrenergic receptor. Rats were treated with reserpine (a norepinephrine depleter) and the pineals exposed to ephedrine. Endogenous norepinephrine normally released by the action of ephedrine was thus absent, and under these conditions, levels of melatonin (aMT) and N-acetylserotonin (aHT) were reduced. N-acetyltransferase (NAT) activity was also reduced, but maintained levels pointing to substantial adrenergic activity of ephedrine as well as norepinephrine released by virtue of the drug's action. A subsequent binding study showed a decrease in beta-adrenergic receptor binding with exposure to ephedrine and a further decrease in ephedrine treated pineals from reserpine treated rats, thus ruling out the occurrence of a supersensitivity phenomenon. It is possible that both ephedrine and released norepinephrine have alpha- and beta-receptor activity. Additional pineal metabolites were isolated and measured in the organ culture experiments. A 16-hour time profile of the production of melatonin (aMT) and N-acetylserotonin (aHT) with norepinephrine and ephedrine treatment provided useful information regarding the course of action of the two agents. A pineal cell-culture system was developed and exposed to ephedrine and norepinephrine. N-acetyltransferase (NAT) activity levels measured after exposure to these agents were raised, confirming the adrenergic activity of both in the model. Finally, an HPLC system coupled to a UV detector was used in an attempt to measure melatonin (aMT) extracted from pineal organ culture media. The results showed that melatonin could be measured by this method, however, a more sensitive detection system was recommended for future work
- Full Text:
- Authors: Welman, Alan David
- Date: 1991
- Subjects: Pineal gland , Cythochemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4279 , http://hdl.handle.net/10962/d1002005 , Pineal gland
- Description: An attempt was made to use the pineal gland as a model for the study of the primary mode of action of sympathoactive agents. Two drugs were investigated, viz. alpha-methyldopa and ephedrine whose mode of action is not entirely clear. Organ cultures of pineal glands from rats treated chronically with alpha-methyldopa showed enhanced conversion of radioactive serotonin to melatonin (aMT) , as well as its precursor Nacetylserotonin (aHT). This treatment was also found to raise Nacetyltransferase (NAT) activity. These increases associated with alpha-methyldopa treatment were further enhanced by the beta-adrenergic agonist, isoproterenol, suggesting a supersensitivity-type effect occurring at the level of the beta-receptor. A subsequent binding study, however, showed a decrease in beta-receptor binding with exposure to alpha-methyldopa, providing mitigating evidence against the occurrence of a supersensitivity phenomenon. It is possible that a metabolite of alpha-methyldopa acts as an alpha 1 and beta-adrenergic agonist, resulting in greater melatonin (aMT) and N-acetylserotonin (aHT) synthesis than by a beta-adrenergic agonist, isoproterenol. Combined treatment of pineals with alpha-methyldopa and an alphareceptor blocker, phentolamine, resulted in melatonin (aMT) , Nacetylserotonin (aHT) , and N-acetyltransferase (NAT) activity levels which were lower than those obtained with alpha-methyldopa treatment alone, thus confirming the alpha-adrenergic activity of the metabolite of alpha-methyldopa. Additional pineal metabolites were isolated and measured simultaneously in the organ culture experiments. Organ cultures of rat pineal glands treated with ephedrine showed raised levels of melatonin (aMT) and N-acetylserotonin (aHT). Treatment with ephedrine also produced raised N-acetyltransferase activity. A further enhancement of these parameters was induced by norepinephrine, suggesting a supersensitivity-type effect occurring at the level of the beta-adrenergic receptor. Rats were treated with reserpine (a norepinephrine depleter) and the pineals exposed to ephedrine. Endogenous norepinephrine normally released by the action of ephedrine was thus absent, and under these conditions, levels of melatonin (aMT) and N-acetylserotonin (aHT) were reduced. N-acetyltransferase (NAT) activity was also reduced, but maintained levels pointing to substantial adrenergic activity of ephedrine as well as norepinephrine released by virtue of the drug's action. A subsequent binding study showed a decrease in beta-adrenergic receptor binding with exposure to ephedrine and a further decrease in ephedrine treated pineals from reserpine treated rats, thus ruling out the occurrence of a supersensitivity phenomenon. It is possible that both ephedrine and released norepinephrine have alpha- and beta-receptor activity. Additional pineal metabolites were isolated and measured in the organ culture experiments. A 16-hour time profile of the production of melatonin (aMT) and N-acetylserotonin (aHT) with norepinephrine and ephedrine treatment provided useful information regarding the course of action of the two agents. A pineal cell-culture system was developed and exposed to ephedrine and norepinephrine. N-acetyltransferase (NAT) activity levels measured after exposure to these agents were raised, confirming the adrenergic activity of both in the model. Finally, an HPLC system coupled to a UV detector was used in an attempt to measure melatonin (aMT) extracted from pineal organ culture media. The results showed that melatonin could be measured by this method, however, a more sensitive detection system was recommended for future work
- Full Text:
A survey of San paintings from the southern Natal Drakensberg
- Authors: Steynberg, Peter John
- Date: 1988
- Subjects: Art, San Rock paintings -- Drakensberg Mountains Cave paintings -- Drakensberg Mountains Art, Prehistoric -- Drakensberg Mountains Art, Prehistoric -- South Africa
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2437 , http://hdl.handle.net/10962/d1004918
- Description: From Introduction: The study of San rock art has undergone several different phases in approach to the interpretation of art. Two approaches are currently in use. The first emphasises the art as narrative or literal representations of San life and its proponents may be called the "art for art's sake" school. Adherents to the second approach make detailed use of the San ethnography on the belief system of these people and are highly critical of the literalists because they provide no such context. The second approach has rapidly gained ascendancy and replaced the "art for art's sake" school over the last twenty years. The watershed came with the researches of Vinnicombe (1967) in the southern Drakensberg and Maggs (1967) in the Western Cape who both embarked upon programs of research which had quantification and numerical analysis at their core, so that they could present "...some objective observations on a given sample of rock paintings in a particular area..." in order to compare and contrast paintings from geographically different areas. What Vinnicombe's numerical analyses clearly showed was that the eland was the most frequently depicted antelope and that it must have played a fundamental role "...in both the economy and the rellgious beliefs of the painters...", which opened up the search for what those beliefs might be and how they could be related to the rock art itself. In order to understand what the rock art was all about it was recognised that researchers had to meaningfully contextualise the art within the social and religious framework of the artists themselves. Without the provision of such a relevant context, as many different interpretations of the paintings could be made as there were people with imaginations. Such a piecemeal approach provides a meaningless jumble of subjective fancy which tells us something about the interpreters but nothing about the rock art. It is unfortunate that the advent of this explicitly social and anthropological approach marks the end of the amateur as a serious interpreter of San rock art, for the juxtaposition of the ethnography with the rock art requires a proper training in which the intricacies of symbol and metaphor can be recognised.
- Full Text:
- Authors: Steynberg, Peter John
- Date: 1988
- Subjects: Art, San Rock paintings -- Drakensberg Mountains Cave paintings -- Drakensberg Mountains Art, Prehistoric -- Drakensberg Mountains Art, Prehistoric -- South Africa
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2437 , http://hdl.handle.net/10962/d1004918
- Description: From Introduction: The study of San rock art has undergone several different phases in approach to the interpretation of art. Two approaches are currently in use. The first emphasises the art as narrative or literal representations of San life and its proponents may be called the "art for art's sake" school. Adherents to the second approach make detailed use of the San ethnography on the belief system of these people and are highly critical of the literalists because they provide no such context. The second approach has rapidly gained ascendancy and replaced the "art for art's sake" school over the last twenty years. The watershed came with the researches of Vinnicombe (1967) in the southern Drakensberg and Maggs (1967) in the Western Cape who both embarked upon programs of research which had quantification and numerical analysis at their core, so that they could present "...some objective observations on a given sample of rock paintings in a particular area..." in order to compare and contrast paintings from geographically different areas. What Vinnicombe's numerical analyses clearly showed was that the eland was the most frequently depicted antelope and that it must have played a fundamental role "...in both the economy and the rellgious beliefs of the painters...", which opened up the search for what those beliefs might be and how they could be related to the rock art itself. In order to understand what the rock art was all about it was recognised that researchers had to meaningfully contextualise the art within the social and religious framework of the artists themselves. Without the provision of such a relevant context, as many different interpretations of the paintings could be made as there were people with imaginations. Such a piecemeal approach provides a meaningless jumble of subjective fancy which tells us something about the interpreters but nothing about the rock art. It is unfortunate that the advent of this explicitly social and anthropological approach marks the end of the amateur as a serious interpreter of San rock art, for the juxtaposition of the ethnography with the rock art requires a proper training in which the intricacies of symbol and metaphor can be recognised.
- Full Text: