A phenomenological investigation into lecturers' understanding of themselves as assessors at Rhodes University
- Authors: Grant, Rose
- Date: 2005
- Subjects: Curriculum-based assessment -- South Africa Education, Higher -- South Africa -- Evaluation Educational tests and measurements -- South Africa Education, Higher -- Evaluation Case studies Universities and colleges -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1315 , http://hdl.handle.net/10962/d1003948
- Description: This thesis sets out to obtain an understanding of what it means to be an assessor in higher education, more especially within the Rhodes University context. The concept of assessment, a highly contentious and complex issue, is examined against a background of competing understandings of the nature and purpose of higher education, including the striving for excellence versus the call to more equitable ideals associated with a mass higher education and training system. An overview of salient issues is presented in which both traditional and alternative paradigms of measurement and assessment theory are explored with a view to considering foundational principles upon which sound assessment practice should be based. Specific methods and instruments of assessment are examined with the purpose of evaluating their potential for empowering students as active participants in their own learning and in the assessment process. In a field in which much of the literature seeks improved assessment merely through the administration of increasingly sophisticated assessment techniques, a phenomenological investigation offered a unique way of understanding the meaning assessors make of their practice. Making use of in-depth interviews with five lecturers at Rhodes University the researcher, interacting in a personal manner with people not viewed as experimental objects but as human subjects, assisted participants in moving towards non-theoretical descriptions that accurately reflected their experience. Insights contained in the data were synthesised and integrated into a consistent description of the essential nature of the experience, the primary endeavour of the phenomenologist being to transform naïve experience into more explicitly detailed conceptual knowledge. The essence of how these educators understand themselves as assessors at Rhodes University is perhaps best encapsulated by a considerable sense of agency or initiative on their part. While participants make use of a variety of assessment strategies, they are conscious that assessment cannot be viewed in isolation from other aspects of their teaching and the curriculum. Not only do they make use of different assessment methods but, conscious of accommodating the diverse needs of students, understand their responsibility in terms of providing learning opportunities to assist students in meeting the course outcomes and fulfilling their potential. Rather than allowing pressures from within and outside of the academy to dictate, these lecturers, with significant hard work, courage and a capacity for reflective practice, have embraced the challenges associated with higher education in a state of transition.
- Full Text:
- Date Issued: 2005
- Authors: Grant, Rose
- Date: 2005
- Subjects: Curriculum-based assessment -- South Africa Education, Higher -- South Africa -- Evaluation Educational tests and measurements -- South Africa Education, Higher -- Evaluation Case studies Universities and colleges -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1315 , http://hdl.handle.net/10962/d1003948
- Description: This thesis sets out to obtain an understanding of what it means to be an assessor in higher education, more especially within the Rhodes University context. The concept of assessment, a highly contentious and complex issue, is examined against a background of competing understandings of the nature and purpose of higher education, including the striving for excellence versus the call to more equitable ideals associated with a mass higher education and training system. An overview of salient issues is presented in which both traditional and alternative paradigms of measurement and assessment theory are explored with a view to considering foundational principles upon which sound assessment practice should be based. Specific methods and instruments of assessment are examined with the purpose of evaluating their potential for empowering students as active participants in their own learning and in the assessment process. In a field in which much of the literature seeks improved assessment merely through the administration of increasingly sophisticated assessment techniques, a phenomenological investigation offered a unique way of understanding the meaning assessors make of their practice. Making use of in-depth interviews with five lecturers at Rhodes University the researcher, interacting in a personal manner with people not viewed as experimental objects but as human subjects, assisted participants in moving towards non-theoretical descriptions that accurately reflected their experience. Insights contained in the data were synthesised and integrated into a consistent description of the essential nature of the experience, the primary endeavour of the phenomenologist being to transform naïve experience into more explicitly detailed conceptual knowledge. The essence of how these educators understand themselves as assessors at Rhodes University is perhaps best encapsulated by a considerable sense of agency or initiative on their part. While participants make use of a variety of assessment strategies, they are conscious that assessment cannot be viewed in isolation from other aspects of their teaching and the curriculum. Not only do they make use of different assessment methods but, conscious of accommodating the diverse needs of students, understand their responsibility in terms of providing learning opportunities to assist students in meeting the course outcomes and fulfilling their potential. Rather than allowing pressures from within and outside of the academy to dictate, these lecturers, with significant hard work, courage and a capacity for reflective practice, have embraced the challenges associated with higher education in a state of transition.
- Full Text:
- Date Issued: 2005
The labour market drop-out rate : a new approach to estimating the returns to government investment in higher education : the case for marine science in South Africa
- Authors: Grootes, Pieter Brian
- Date: 2005
- Subjects: Labor market Marine scientists -- South Africa Education -- Economic aspects -- South Africa Higher education and state -- South Africa Education -- Social aspects Human capital -- South Africa Education, Higher -- Economic aspects -- South Africa
- Language: English
- Type: Thesis , Masters , MEcon
- Identifier: vital:950 , http://hdl.handle.net/10962/d1002684
- Description: The private and social returns to education literature share the same conclusion: that education is beneficial for both the individual and society. However, the theoretical underpinnings are flawed as the literature does not account for the main feature that leads to the acquisition of education: the private demand for education. An understanding of the factors that motivate the individual to invest in education would lead to a deeper insight as to why both private and social returns to education exist, and would provide a clearer framework on which to base the government funding of education. This thesis provides a first attempt at filling this gap by introducing a method of estimating the returns to government investment in education, which is labelled the ‘labour market drop-out rate approach’. The approach focuses on the social return to education, not in terms of graduate earnings, but in terms of the interaction of the graduate with the economy. The approach introduces a measure of expertise utilisation, based on the premise that there is no social return to an individual acquiring education if he or she does not utilise the acquired knowledge base on entering the labour market. The approach is tested using the labour market for marine scientists in South Africa as a case study. In this case the private demand for education is found to be heavily influenced by the provision of student bursaries from the National Research Foundation, with a resulting estimate of the social return to a degree in marine science being a mere 20% to 25%. Owing to this, a new approach to government investment in marine science is introduced, that of graduate contribution schemes. Of broader significance is the ease of application of this approach, it may be adopted to analyse any funding programme in which a government may decide to invest. As such, the labour market drop-out rate provides an extension to the returns to education literature through its theoretical dealings of the private demand for education, as well as a practical tool which government agencies can use to evaluate the efficacy of any government funding of education.
- Full Text:
- Date Issued: 2005
- Authors: Grootes, Pieter Brian
- Date: 2005
- Subjects: Labor market Marine scientists -- South Africa Education -- Economic aspects -- South Africa Higher education and state -- South Africa Education -- Social aspects Human capital -- South Africa Education, Higher -- Economic aspects -- South Africa
- Language: English
- Type: Thesis , Masters , MEcon
- Identifier: vital:950 , http://hdl.handle.net/10962/d1002684
- Description: The private and social returns to education literature share the same conclusion: that education is beneficial for both the individual and society. However, the theoretical underpinnings are flawed as the literature does not account for the main feature that leads to the acquisition of education: the private demand for education. An understanding of the factors that motivate the individual to invest in education would lead to a deeper insight as to why both private and social returns to education exist, and would provide a clearer framework on which to base the government funding of education. This thesis provides a first attempt at filling this gap by introducing a method of estimating the returns to government investment in education, which is labelled the ‘labour market drop-out rate approach’. The approach focuses on the social return to education, not in terms of graduate earnings, but in terms of the interaction of the graduate with the economy. The approach introduces a measure of expertise utilisation, based on the premise that there is no social return to an individual acquiring education if he or she does not utilise the acquired knowledge base on entering the labour market. The approach is tested using the labour market for marine scientists in South Africa as a case study. In this case the private demand for education is found to be heavily influenced by the provision of student bursaries from the National Research Foundation, with a resulting estimate of the social return to a degree in marine science being a mere 20% to 25%. Owing to this, a new approach to government investment in marine science is introduced, that of graduate contribution schemes. Of broader significance is the ease of application of this approach, it may be adopted to analyse any funding programme in which a government may decide to invest. As such, the labour market drop-out rate provides an extension to the returns to education literature through its theoretical dealings of the private demand for education, as well as a practical tool which government agencies can use to evaluate the efficacy of any government funding of education.
- Full Text:
- Date Issued: 2005
Strategies for sustaining family business through succession planning and family creed
- Authors: Gwiliza, Nwabisa
- Date: 2005
- Subjects: Family-owned business enterprises -- South Africa -- Succession , Family corporations -- South Africa -- Management
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8537 , http://hdl.handle.net/10948/193 , Family-owned business enterprises -- South Africa -- Succession , Family corporations -- South Africa -- Management
- Description: Family business literature reveals that the majority of family businesses do not make it to the second generation, and quite a few are fortunate to be passed onto the third generation. Succession planning is the critical issue that enhances continuity of the family business. Relational influences indicate that the balancing of family systems and business systems is more likely to encourage high quality succession. The development of effective practical governance systems can help the family business achieve its strategy. External influences indicate that owner role adjustment, defined as the predecessor’s “letting go” in the firm, as well as the development and mentoring of the successor, shape the effectiveness of succession in the family business.
- Full Text:
- Date Issued: 2005
- Authors: Gwiliza, Nwabisa
- Date: 2005
- Subjects: Family-owned business enterprises -- South Africa -- Succession , Family corporations -- South Africa -- Management
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8537 , http://hdl.handle.net/10948/193 , Family-owned business enterprises -- South Africa -- Succession , Family corporations -- South Africa -- Management
- Description: Family business literature reveals that the majority of family businesses do not make it to the second generation, and quite a few are fortunate to be passed onto the third generation. Succession planning is the critical issue that enhances continuity of the family business. Relational influences indicate that the balancing of family systems and business systems is more likely to encourage high quality succession. The development of effective practical governance systems can help the family business achieve its strategy. External influences indicate that owner role adjustment, defined as the predecessor’s “letting go” in the firm, as well as the development and mentoring of the successor, shape the effectiveness of succession in the family business.
- Full Text:
- Date Issued: 2005
Training needs for municipal employees: a case study of Makana Municipality
- Authors: Hamaamba, Tyson
- Date: 2005
- Subjects: Municipal officials and employees -- Training of -- South Africa -- Grahamstown Environmental education -- South Africa -- Grahamstown Local officials and employees -- Training of -- South Africa -- Grahamstown Municipal water supply -- South Africa -- Grahamstown Sanitation -- South Africa -- Grahamstown Environmental health -- South Africa -- Grahamstown Environmental management -- South Africa -- Grahamstown Livestock -- Management -- South Africa -- Grahamstown Refuse and refuse disposal -- South Africa -- Grahamstown Fire departments -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1943 , http://hdl.handle.net/10962/d1007952
- Description: This study investigated the education and training needs for municipal employees in order to inform an education and training strategy that would address environmental management challenges in Makana local municipality in Grahamstown, Eastern Cape province. The research was conducted as a qualitative case study that made use of questionnaires, document analysis, focus group discussions and interviews as instruments for data generation. Samples of respondents were selected from Makana Municipality employees in top and middle management positions, professionals/technicians and workers, including elected councillors. The study was contextualised through establishing environmental management issues in Makana municipality; establishing organisational needs; development of a learner profile; and through a review of policies and recent trends in adult education. The study established that the Makana Municipality employees are most concerned with the following issues: sanitation; solid waste management; livestock management and fire management. These issues require primary environmental competences among all council employees (top and middle management, professionals and technicians, workers and councillors who work on part-time basis). The educational implications needed to respond to these issues also require an understanding of legislation. The study also established that technical education and training which includes planning, project management, and financial and budgeting competences are necessary amongst the management and professionals. These competences may enable them to develop capacity in environmental management. This study further established the need for social education which includes competences such as communication and social justice. These competences should be developed amongst members of the same group as they need to involve the community in management of the environment. This should enable the municipality to create job opportunities and help change negative attitudes.
- Full Text:
- Date Issued: 2005
- Authors: Hamaamba, Tyson
- Date: 2005
- Subjects: Municipal officials and employees -- Training of -- South Africa -- Grahamstown Environmental education -- South Africa -- Grahamstown Local officials and employees -- Training of -- South Africa -- Grahamstown Municipal water supply -- South Africa -- Grahamstown Sanitation -- South Africa -- Grahamstown Environmental health -- South Africa -- Grahamstown Environmental management -- South Africa -- Grahamstown Livestock -- Management -- South Africa -- Grahamstown Refuse and refuse disposal -- South Africa -- Grahamstown Fire departments -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1943 , http://hdl.handle.net/10962/d1007952
- Description: This study investigated the education and training needs for municipal employees in order to inform an education and training strategy that would address environmental management challenges in Makana local municipality in Grahamstown, Eastern Cape province. The research was conducted as a qualitative case study that made use of questionnaires, document analysis, focus group discussions and interviews as instruments for data generation. Samples of respondents were selected from Makana Municipality employees in top and middle management positions, professionals/technicians and workers, including elected councillors. The study was contextualised through establishing environmental management issues in Makana municipality; establishing organisational needs; development of a learner profile; and through a review of policies and recent trends in adult education. The study established that the Makana Municipality employees are most concerned with the following issues: sanitation; solid waste management; livestock management and fire management. These issues require primary environmental competences among all council employees (top and middle management, professionals and technicians, workers and councillors who work on part-time basis). The educational implications needed to respond to these issues also require an understanding of legislation. The study also established that technical education and training which includes planning, project management, and financial and budgeting competences are necessary amongst the management and professionals. These competences may enable them to develop capacity in environmental management. This study further established the need for social education which includes competences such as communication and social justice. These competences should be developed amongst members of the same group as they need to involve the community in management of the environment. This should enable the municipality to create job opportunities and help change negative attitudes.
- Full Text:
- Date Issued: 2005
Developing a model for establishing, implementing, and maintaining learnerships in South Africa
- Authors: Hamlet, Brian
- Date: 2005
- Subjects: Employees -- Training of -- South Africa , Experiential learning -- South Africa , Education, Cooperative -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9377 , http://hdl.handle.net/10948/156 , Employees -- Training of -- South Africa , Experiential learning -- South Africa , Education, Cooperative -- South Africa
- Description: The research problem in this study was to identify how successful the methods are that organisations use within the Manufacturing Engineering and Related Services Education and Training Authorities (MERSETA) chambers to develop, implement and maintain learnerships. To achieve this aim a literature examination to determine the aspects of workplace learning were explored, including the various perspectives of learning, together with an investigation into workplace learning. Further, apprenticeships, traineeships, learnerships were discussed; including the concepts vocational education and training standards, and competence explored. Finally a process model for effective learnership implementation was presented based on international approaches together with the South African models and current practices. - v - The process learnership model served as a basis for drawing up a survey questionnaire to establish the extent to which organisations agreed or disagreed with the learnership model developed. The survey was limited to the “automobile” and “new tyre” chambers of the MERSETA. The results obtained from the empirical study indicted a high degree of agreement with the process model for effective learnership implementation. The results obtained from the quantitative data, and qualitative data were used to adapt the learnership process model, and produce a six-phase integrated learnership model. From the survey it become evident that organisations needed to be sensitised and educated as to learnerships before considering more seriously learnership implementation. Further, it emerged that learnerships cannot only be effective within a process approach, and that it should also take place within a positive “organisational learning culture”. Organisations and Sector Education and Training Authorities (SETAs) can now use the six-phase integrated learnership model with confidence, as there was a high degree of agreement with the learnership model that was developed as part of this research study. The six-phase integrated learnership model has been comprehensively developed and surveyed by organisations that are currently implementing learnerships on a large scale. Organisations and SETAs can now give effect to the Skills Development Act No. 97 of 1998, and contribute to the National skills Development Strategy of 2001, which aims to improve the workplace skills of all South Africans.
- Full Text:
- Date Issued: 2005
- Authors: Hamlet, Brian
- Date: 2005
- Subjects: Employees -- Training of -- South Africa , Experiential learning -- South Africa , Education, Cooperative -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9377 , http://hdl.handle.net/10948/156 , Employees -- Training of -- South Africa , Experiential learning -- South Africa , Education, Cooperative -- South Africa
- Description: The research problem in this study was to identify how successful the methods are that organisations use within the Manufacturing Engineering and Related Services Education and Training Authorities (MERSETA) chambers to develop, implement and maintain learnerships. To achieve this aim a literature examination to determine the aspects of workplace learning were explored, including the various perspectives of learning, together with an investigation into workplace learning. Further, apprenticeships, traineeships, learnerships were discussed; including the concepts vocational education and training standards, and competence explored. Finally a process model for effective learnership implementation was presented based on international approaches together with the South African models and current practices. - v - The process learnership model served as a basis for drawing up a survey questionnaire to establish the extent to which organisations agreed or disagreed with the learnership model developed. The survey was limited to the “automobile” and “new tyre” chambers of the MERSETA. The results obtained from the empirical study indicted a high degree of agreement with the process model for effective learnership implementation. The results obtained from the quantitative data, and qualitative data were used to adapt the learnership process model, and produce a six-phase integrated learnership model. From the survey it become evident that organisations needed to be sensitised and educated as to learnerships before considering more seriously learnership implementation. Further, it emerged that learnerships cannot only be effective within a process approach, and that it should also take place within a positive “organisational learning culture”. Organisations and Sector Education and Training Authorities (SETAs) can now use the six-phase integrated learnership model with confidence, as there was a high degree of agreement with the learnership model that was developed as part of this research study. The six-phase integrated learnership model has been comprehensively developed and surveyed by organisations that are currently implementing learnerships on a large scale. Organisations and SETAs can now give effect to the Skills Development Act No. 97 of 1998, and contribute to the National skills Development Strategy of 2001, which aims to improve the workplace skills of all South Africans.
- Full Text:
- Date Issued: 2005
An intersubjective perspective on the role of personal therapy in being a psychotherapist
- Authors: Haumann, Hester Johanna
- Date: 2005
- Subjects: Psychodynamic psychotherapy Psychotherapy Clinical psychology Psychotherapists -- Psychology Psychoanalysis Countertransference(Psychology)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2988 , http://hdl.handle.net/10962/d1002497
- Description: The purpose of this study was to explore how personal therapy influences experienced psychodynamic psychotherapists’ ways of being clinicians, and, by implication, their professional development. A hermeneutic research method, which also drew upon aspects of grounded theory methodology, was therefore devised to explore and examine how personal therapy and professional practice relate to each other and to the therapist’s development, and to deepen this descriptive account into a more differentiated and theoretically viable understanding. In-depth, semi-structured interviews were conducted with eight psychodynamic psychotherapists who were working as clinicians and who were concurrently in therapy. Keeping the research objective in mind, a list of questions was developed from the interview material through which the data was re-read and edited. In accordance with the aims of the study, and as suggested by the results of the initial phase of the textual analysis, intersubjective theory, mainly that of Jessica Benjamin, was used to generate a conceptual framework through which the interview material was further interpreted. This foregrounded the shifting power distributions and the varying processes of identification between the treating therapists and the participants. The Jungian notion of the wounded healer was intersubjectively reconfigured as indicating a therapist whose (often unacknowledged) needs and vulnerabilities engender a proclivity to relate to patients as objects rather than subjects. The participants could all be described as having started out their professional lives as wounded healers. The effects of personal therapy on their clinical work were conceptualised in terms of increased abilities for subject-to-subject relating. These were linked to augmented capacities for reflective and symbolic thinking and an enhanced openness to the implicit, unformulated and opaque aspects of experiences in the therapeutic space. Finally an intersubjective model of personal therapy and development as a therapist was generated. It was concluded that because of the focus on the therapeutic relationship as the vehicle for change in psychodynamic psychotherapy, as well as the current increasing emphasis on the use of the therapist’s subjectivity, the therapist’s capacity to engage in and sustain subject-tosubject relating and, by implication, the therapist’s personal therapy, are of pivotal importance for all therapists doing the work of psychodynamic psychotherapy.
- Full Text:
- Date Issued: 2005
- Authors: Haumann, Hester Johanna
- Date: 2005
- Subjects: Psychodynamic psychotherapy Psychotherapy Clinical psychology Psychotherapists -- Psychology Psychoanalysis Countertransference(Psychology)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2988 , http://hdl.handle.net/10962/d1002497
- Description: The purpose of this study was to explore how personal therapy influences experienced psychodynamic psychotherapists’ ways of being clinicians, and, by implication, their professional development. A hermeneutic research method, which also drew upon aspects of grounded theory methodology, was therefore devised to explore and examine how personal therapy and professional practice relate to each other and to the therapist’s development, and to deepen this descriptive account into a more differentiated and theoretically viable understanding. In-depth, semi-structured interviews were conducted with eight psychodynamic psychotherapists who were working as clinicians and who were concurrently in therapy. Keeping the research objective in mind, a list of questions was developed from the interview material through which the data was re-read and edited. In accordance with the aims of the study, and as suggested by the results of the initial phase of the textual analysis, intersubjective theory, mainly that of Jessica Benjamin, was used to generate a conceptual framework through which the interview material was further interpreted. This foregrounded the shifting power distributions and the varying processes of identification between the treating therapists and the participants. The Jungian notion of the wounded healer was intersubjectively reconfigured as indicating a therapist whose (often unacknowledged) needs and vulnerabilities engender a proclivity to relate to patients as objects rather than subjects. The participants could all be described as having started out their professional lives as wounded healers. The effects of personal therapy on their clinical work were conceptualised in terms of increased abilities for subject-to-subject relating. These were linked to augmented capacities for reflective and symbolic thinking and an enhanced openness to the implicit, unformulated and opaque aspects of experiences in the therapeutic space. Finally an intersubjective model of personal therapy and development as a therapist was generated. It was concluded that because of the focus on the therapeutic relationship as the vehicle for change in psychodynamic psychotherapy, as well as the current increasing emphasis on the use of the therapist’s subjectivity, the therapist’s capacity to engage in and sustain subject-tosubject relating and, by implication, the therapist’s personal therapy, are of pivotal importance for all therapists doing the work of psychodynamic psychotherapy.
- Full Text:
- Date Issued: 2005
Operationally defining sexual orientation : towards the development of a fundamental measure of adolescent sexual responsiveness variations
- Authors: Heath, Lance Julian
- Date: 2005
- Subjects: Sexual orientation Homosexuality Psychometrics Teenagers--Sexual behavior
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1681 , http://hdl.handle.net/10962/d1003564
- Description: Much published work has pointed to the need for the development of a sound operational definition of sexual orientation in order to enable the research in this area to progress. To contribute to this process the current research set out to develop two measures of sexual orientation and examine their psychometric properties. In order to develop relevant tools historical, conceptual and operational definitions of sexual orientation were critically examined and standard questionnaire development techniques applied. The first scale consisted of 32 items and was administered to a total of 835 adolescents, comprising three sub-groups (189 Grade 11 Scholars, 547 First Year and 99 Third Year Psychology Students). A Cronbach alpha coefficient of 0.85 was calculated indicating that this instrument had very good internal consistency reliability. Similar factors emerged in each of the sample sub-groups when factor analyses were performed suggesting that this instrument has good external and construct validities. These factors each had respectable Cronbach alpha coefficients indicating their own internal consistency. The four factors which consistently emerged were Same Sex Responsiveness, Opposite Sex Responsiveness, Previous Month’s Same Sex Responsiveness and Previous Month’s Opposite Sex Responsiveness. The second scale consisted of 16 items and was administered to 646 adolescents, comprising the latter two sub-groups referred to above. A Cronbach alpha coefficient of 0.82 was calculated indicating that this instrument also had very good internal consistency reliability. Once again similar factors with generally good internal consistency emerged in factor analysis suggesting that this too was a valid instrument. The factors that emerged from the second scale were Same Sex Responsiveness, Unattractive Opposite Sex Responsiveness, Attractive Opposite Sex Responsiveness and Attraction. Future developments, adjustments and applications of the instruments as well as implications for the arena of sexual orientation research are discussed. In the light of the dearth of information with regard to the sexual orientations of South African adolescents the current study also briefly explored and presented the sample’s responses in terms of the dimensions of each questionnaire as well as how each emerging factor related to the demographics (education level, gender, sexual orientation self-label and age) of the sample.
- Full Text:
- Date Issued: 2005
- Authors: Heath, Lance Julian
- Date: 2005
- Subjects: Sexual orientation Homosexuality Psychometrics Teenagers--Sexual behavior
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1681 , http://hdl.handle.net/10962/d1003564
- Description: Much published work has pointed to the need for the development of a sound operational definition of sexual orientation in order to enable the research in this area to progress. To contribute to this process the current research set out to develop two measures of sexual orientation and examine their psychometric properties. In order to develop relevant tools historical, conceptual and operational definitions of sexual orientation were critically examined and standard questionnaire development techniques applied. The first scale consisted of 32 items and was administered to a total of 835 adolescents, comprising three sub-groups (189 Grade 11 Scholars, 547 First Year and 99 Third Year Psychology Students). A Cronbach alpha coefficient of 0.85 was calculated indicating that this instrument had very good internal consistency reliability. Similar factors emerged in each of the sample sub-groups when factor analyses were performed suggesting that this instrument has good external and construct validities. These factors each had respectable Cronbach alpha coefficients indicating their own internal consistency. The four factors which consistently emerged were Same Sex Responsiveness, Opposite Sex Responsiveness, Previous Month’s Same Sex Responsiveness and Previous Month’s Opposite Sex Responsiveness. The second scale consisted of 16 items and was administered to 646 adolescents, comprising the latter two sub-groups referred to above. A Cronbach alpha coefficient of 0.82 was calculated indicating that this instrument also had very good internal consistency reliability. Once again similar factors with generally good internal consistency emerged in factor analysis suggesting that this too was a valid instrument. The factors that emerged from the second scale were Same Sex Responsiveness, Unattractive Opposite Sex Responsiveness, Attractive Opposite Sex Responsiveness and Attraction. Future developments, adjustments and applications of the instruments as well as implications for the arena of sexual orientation research are discussed. In the light of the dearth of information with regard to the sexual orientations of South African adolescents the current study also briefly explored and presented the sample’s responses in terms of the dimensions of each questionnaire as well as how each emerging factor related to the demographics (education level, gender, sexual orientation self-label and age) of the sample.
- Full Text:
- Date Issued: 2005
The subjective well-being of divorced single custodial parents
- Authors: Henry, Jaci Lee
- Date: 2005
- Subjects: Single parents -- South Africa , Divorced parents -- South Africa , Self-actualization (Psychology)
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9841 , http://hdl.handle.net/10948/368 , Single parents -- South Africa , Divorced parents -- South Africa , Self-actualization (Psychology)
- Description: As the divorce rate consistently rises, the occurrence of single parent families are becoming increasingly prevalent. Despite the marked increase in single custodial parents, research on this population (and more importantly, into the positive aspects such as their subjective well-being) has been neglected. Over the past three decades, psychologists have shifted the emphasis of their research from examining demographic and pathogenic factors to a positive psychology framework focusing on personality and resilience. The general aim of this study was to explore and describe the subjective wellbeing, including satisfaction with life and general happiness, of divorced, single custodial parents. In addition, this study aimed to identify potential patterns among the aspects of subjective well-being investigated and aimed to explore the relationships between these patterns. Thirty-five participants were included for participation in this study by means of non-probability, purposive sampling. The research measures included a biographical questionnaire, the Satisfaction with Life Scale (SWLS) and Affectometer-2 Scale (AFM-2). The data were analysed by the researcher and an independent statistician in terms of descriptive statistics and cluster analysis, or according to content analysis. This reflects a triangulation data collection and analysis method. Key findings included the following: The results of the SWLS indicated that the majority of participants reported being slightly dissatisfied with their lives. The results of the AFM-2 indicated that the participants generally had high levels of positive affect, and low levels of negative affect. However, the participants’ overall levels of happiness were still relatively low. A four cluster solution was obtained, with the clusters being significantly different from each other on all input variables. The first cluster experienced high levels of positive affect, low levels of negative affect, and high levels of overall happiness. The second cluster experienced predominantly slight dissatisfaction with their lives, high levels of positive affect, low levels of negative affect, and slightly low levels of overall happiness. The third cluster reported mostly dissatisfaction with their lives, low levels of positive affect, high levels of negative affect, and very low levels of overall happiness. The fourth cluster experienced predominantly slight satisfaction with xi life, slightly high levels of positive affect, neutral levels of negative affect, and low levels of overall happiness. It appeared that clusters containing participants who were satisfied with their jobs, were involved in a personal relationship and who participated in leisure activities, all experienced higher levels of subjective well-being. Overall, this study emphasises the value of and the need for South African research on the subjective wellbeing of divorced, single custodial parents.
- Full Text:
- Date Issued: 2005
- Authors: Henry, Jaci Lee
- Date: 2005
- Subjects: Single parents -- South Africa , Divorced parents -- South Africa , Self-actualization (Psychology)
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9841 , http://hdl.handle.net/10948/368 , Single parents -- South Africa , Divorced parents -- South Africa , Self-actualization (Psychology)
- Description: As the divorce rate consistently rises, the occurrence of single parent families are becoming increasingly prevalent. Despite the marked increase in single custodial parents, research on this population (and more importantly, into the positive aspects such as their subjective well-being) has been neglected. Over the past three decades, psychologists have shifted the emphasis of their research from examining demographic and pathogenic factors to a positive psychology framework focusing on personality and resilience. The general aim of this study was to explore and describe the subjective wellbeing, including satisfaction with life and general happiness, of divorced, single custodial parents. In addition, this study aimed to identify potential patterns among the aspects of subjective well-being investigated and aimed to explore the relationships between these patterns. Thirty-five participants were included for participation in this study by means of non-probability, purposive sampling. The research measures included a biographical questionnaire, the Satisfaction with Life Scale (SWLS) and Affectometer-2 Scale (AFM-2). The data were analysed by the researcher and an independent statistician in terms of descriptive statistics and cluster analysis, or according to content analysis. This reflects a triangulation data collection and analysis method. Key findings included the following: The results of the SWLS indicated that the majority of participants reported being slightly dissatisfied with their lives. The results of the AFM-2 indicated that the participants generally had high levels of positive affect, and low levels of negative affect. However, the participants’ overall levels of happiness were still relatively low. A four cluster solution was obtained, with the clusters being significantly different from each other on all input variables. The first cluster experienced high levels of positive affect, low levels of negative affect, and high levels of overall happiness. The second cluster experienced predominantly slight dissatisfaction with their lives, high levels of positive affect, low levels of negative affect, and slightly low levels of overall happiness. The third cluster reported mostly dissatisfaction with their lives, low levels of positive affect, high levels of negative affect, and very low levels of overall happiness. The fourth cluster experienced predominantly slight satisfaction with xi life, slightly high levels of positive affect, neutral levels of negative affect, and low levels of overall happiness. It appeared that clusters containing participants who were satisfied with their jobs, were involved in a personal relationship and who participated in leisure activities, all experienced higher levels of subjective well-being. Overall, this study emphasises the value of and the need for South African research on the subjective wellbeing of divorced, single custodial parents.
- Full Text:
- Date Issued: 2005
Establishment and impact of the sap-sucking mirid, Falconia intermedia (Distant) (Hemiptera: Miridae) on Lantana camara (Verbenaceae) varieties in the Eastern Cape Province, South Africa
- Heshula, Unathi-Nkosi Lelethu Peter
- Authors: Heshula, Unathi-Nkosi Lelethu Peter
- Date: 2005
- Subjects: Lantana camara -- South Africa -- Eastern Cape , Biological pest control agents -- South Africa -- Eastern Cape , Hemiptera -- South Africa -- Eastern Cape , Miridae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5832 , http://hdl.handle.net/10962/d1008085
- Description: The biological control of the weedy complex Lantana camara (L.) (Verbenaceae) has been ongoing in South Africa for over 40 years. Despite this, the weed is still not under sufficient control and continues to invade new territories in the country. The biological control programme needs to be bolstered with releases of new and potentially damaging biological control agents. A promising biological control agent endemic to Central America, Falconia intermedia (Distant) (Hemiptera: Miridae), was imported into quarantine from Jamaica in 1994. This agent was released on sites in KwaZulu-Natal and Limpopo provinces of South Africa in 1999. Even though it initially established and damaged L. camara, populations died out at most of the release sites. As varietal difference and adverse climate have been cited as the reason for non-establishment and ineffective control in L. camara biocontrol programmes worldwide, this study attempts to investigate the role that these two factors play in this weed herbivore relationship. Laboratory no-choice trials were conducted to determine the varietal performance of F intermedia, among five Eastern Cape varieties of the weed from East London, Whitney Farm, Heather Glen Farm, Port Alfred and Lyndhurst Farm, and a variety from the Plant Protection Research Institute (PPRI), Pretoria. However, there were differences in performance as the adult mirids performed better on white-pink varieties from Whitney Farm and Heather Glen Farm. To test varietal preference in field conditions, field releases of F intermedia were also made at East London, Whitney Farm, Heather Glen Farm, Port Alfred and Lyndhurst Farm. Post release evaluations were conducted monthly for two years (2002 and 2003). The insect established at East London and Whitney Farm, both of which have white-pink varieties. Insect populations quickly died out at the Lyndhurst Farm and Port Alfred sites, which have dark pink varieties. It is suggested that field conditions may have resulted in poor plant quality and led indirectly to varietal preference, and to non-establishment at these two sites. With the onset of cooler weather, populations disappeared at Heather Glen Farm. This suggested that F. intermedia was suitable for release in more subtropical areas within South Africa where climatic conditions would be suitable throughout the year. The mirid performed well at Whitney Farm, resulting in significant reduction in plant growth parameters such as height and percentage cover, and increasing the cover of other flora growing beneath L. camara plants. Finally, ways to improve the efficacy of this agent are considered in an effort towards better control of L. camara in South Africa.
- Full Text:
- Date Issued: 2005
- Authors: Heshula, Unathi-Nkosi Lelethu Peter
- Date: 2005
- Subjects: Lantana camara -- South Africa -- Eastern Cape , Biological pest control agents -- South Africa -- Eastern Cape , Hemiptera -- South Africa -- Eastern Cape , Miridae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5832 , http://hdl.handle.net/10962/d1008085
- Description: The biological control of the weedy complex Lantana camara (L.) (Verbenaceae) has been ongoing in South Africa for over 40 years. Despite this, the weed is still not under sufficient control and continues to invade new territories in the country. The biological control programme needs to be bolstered with releases of new and potentially damaging biological control agents. A promising biological control agent endemic to Central America, Falconia intermedia (Distant) (Hemiptera: Miridae), was imported into quarantine from Jamaica in 1994. This agent was released on sites in KwaZulu-Natal and Limpopo provinces of South Africa in 1999. Even though it initially established and damaged L. camara, populations died out at most of the release sites. As varietal difference and adverse climate have been cited as the reason for non-establishment and ineffective control in L. camara biocontrol programmes worldwide, this study attempts to investigate the role that these two factors play in this weed herbivore relationship. Laboratory no-choice trials were conducted to determine the varietal performance of F intermedia, among five Eastern Cape varieties of the weed from East London, Whitney Farm, Heather Glen Farm, Port Alfred and Lyndhurst Farm, and a variety from the Plant Protection Research Institute (PPRI), Pretoria. However, there were differences in performance as the adult mirids performed better on white-pink varieties from Whitney Farm and Heather Glen Farm. To test varietal preference in field conditions, field releases of F intermedia were also made at East London, Whitney Farm, Heather Glen Farm, Port Alfred and Lyndhurst Farm. Post release evaluations were conducted monthly for two years (2002 and 2003). The insect established at East London and Whitney Farm, both of which have white-pink varieties. Insect populations quickly died out at the Lyndhurst Farm and Port Alfred sites, which have dark pink varieties. It is suggested that field conditions may have resulted in poor plant quality and led indirectly to varietal preference, and to non-establishment at these two sites. With the onset of cooler weather, populations disappeared at Heather Glen Farm. This suggested that F. intermedia was suitable for release in more subtropical areas within South Africa where climatic conditions would be suitable throughout the year. The mirid performed well at Whitney Farm, resulting in significant reduction in plant growth parameters such as height and percentage cover, and increasing the cover of other flora growing beneath L. camara plants. Finally, ways to improve the efficacy of this agent are considered in an effort towards better control of L. camara in South Africa.
- Full Text:
- Date Issued: 2005
Primary school children's experiences in their loss of a parent
- Authors: Hildebrand, Paula
- Date: 2005
- Subjects: Children and death -- South Africa , Parents -- South Africa -- Death -- Psychological aspects , Grief in children
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9984 , http://hdl.handle.net/10948/446 , Children and death -- South Africa , Parents -- South Africa -- Death -- Psychological aspects , Grief in children
- Description: This study aims to discover the meaning that primary school children place on the loss of a parent and the impact it has on the children’s lives. As it is an emotive topic, and because of the difficulties of interviewing children, qualitative techniques of research data collection are considered the most appropriate. The study will explore, discover and describe children’s personal experiences of loss in a phenomenological and contextual manner. The sample in the study will be selected according to non-probability and purposive sampling techniques. Because children are being interviewed, the researcher will ethically approach gatekeepers for permission, and gain their informed consent. Data will be collected using semi-structured interviews, in which the researcher will interact with the interviewees in a natural setting. Data analysis will be done according to Tesch’s eight steps for analysing qualitative research data (Creswell, 1994:155). Once this process has been completed, the data will be verified against the four criteria that Guba (in Krefting, 1991:214-222) developed for testing the trustworthiness of qualitative research findings. The results of the study, as well as conclusions and recommendations drawn from the data, will be disseminated by means of a written report.
- Full Text:
- Date Issued: 2005
- Authors: Hildebrand, Paula
- Date: 2005
- Subjects: Children and death -- South Africa , Parents -- South Africa -- Death -- Psychological aspects , Grief in children
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9984 , http://hdl.handle.net/10948/446 , Children and death -- South Africa , Parents -- South Africa -- Death -- Psychological aspects , Grief in children
- Description: This study aims to discover the meaning that primary school children place on the loss of a parent and the impact it has on the children’s lives. As it is an emotive topic, and because of the difficulties of interviewing children, qualitative techniques of research data collection are considered the most appropriate. The study will explore, discover and describe children’s personal experiences of loss in a phenomenological and contextual manner. The sample in the study will be selected according to non-probability and purposive sampling techniques. Because children are being interviewed, the researcher will ethically approach gatekeepers for permission, and gain their informed consent. Data will be collected using semi-structured interviews, in which the researcher will interact with the interviewees in a natural setting. Data analysis will be done according to Tesch’s eight steps for analysing qualitative research data (Creswell, 1994:155). Once this process has been completed, the data will be verified against the four criteria that Guba (in Krefting, 1991:214-222) developed for testing the trustworthiness of qualitative research findings. The results of the study, as well as conclusions and recommendations drawn from the data, will be disseminated by means of a written report.
- Full Text:
- Date Issued: 2005
The oxidative coupling of phenols using stoichiometric metal oxidants
- Authors: Hoffmann, Eric
- Date: 2005
- Subjects: Phenols , Oxidation , Stoichiometry
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10977 , http://hdl.handle.net/10948/180 , Phenols , Oxidation , Stoichiometry
- Description: The oxidative coupling of 2,6-di-t-butylphenol under mild reaction conditions is well documented and the subject of many patents. However, the coupling of other monoand di- substituted phenols is not as well documented and thus there is scope for further investigation for providing a convenient, environmentally friendly and economically viable method for the oxidative coupling of these phenols. In this study, the oxidative coupling of a variety of alkylated phenolic substrates, 2-tbutylphenol, 2,6-di-t-butylphenol, 2,4 -di-t-butylphenol and ,4-dimethylphenol, using a range of different oxidizing agents, were investigated by means of experimental and/or theoretical means. The dibutylated aromatics provided the highest selectivities to their respective coupled products, with results obtained with the dimethyl analogue being only satisfactory, and that for 2 -t-butylphenol being totally inefficient. PM3 Molecular orbital (MO) calculations were used to predict the possible modes of coupling for the substrates 2,6 -di-t-butylphenol and 2,4-di-t-butylphenol, and these results were then compared with those obtained experimentally in the laboratory. Preliminarily, the coupling of unsubstituted phenolics was also assessed by means of MO calculations. Much emphasis was placed on Ce(IV) as the oxidant, and the reaction conditions under which it was used and the results that were obtained have not been reported before and are therefore novel. The oxidation of 2,4-di-t-butylphenol using Ce(IV) in the presence of methanesulphonic acid was optimized to afford high yields and selectivities to the desired ortho C-ortho C coupled product under mild reaction conditions. Various reaction parameters were also investigated in this case, such as varying the MeSO3H concentration, the solvent, the reaction temperature, the reaction time, the substrate loading, the rate of oxidant addition and the substrate to oxidant ratio. Ce(IV) also gave a high selectivity to the para C-para C coupled product when IX using 2,6-di-t-butylphenol as the substrate. However, it was not as effective with 2,4- dimethylphenol, and even less so with 2-t-butylphenol. The oxidation reactions of 2-t-butylphenol and 2,4-dimethylphenol with various coupling agents were also investigated with the intention of obtaining high selectivities to the respective desired coupled products. In these studies, 2-t-butylphenol afforded a large number of products, irrespective of the oxidant used. The dimethyl analogue was more selective, but results were not optimal. It was clear that the number of substituents on the phenol ring, their nature and their position with regards to the hydroxyl moiety was of great importance and made a significant impact on the preferred coupling mode of the substrate. It was observed that steric effects also played a major role in the outcome of these reactions: 2,6-di-t-butylphenol never afforded any C-O coupled products whereas 2-t-butylphenol, 2,4-di-t-butylphenol and 2,4-dimethylphenol all appeared to undergo some C-O coupling. Finally, reaction mechanisms were provided for both the K3Fe(CN)6 and Ce(IV) work, these reacting in basic and acidic media, respectively. It was proposed that both of these mechanisms operate through the initial formation of the phenoxyl radical.
- Full Text:
- Date Issued: 2005
- Authors: Hoffmann, Eric
- Date: 2005
- Subjects: Phenols , Oxidation , Stoichiometry
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10977 , http://hdl.handle.net/10948/180 , Phenols , Oxidation , Stoichiometry
- Description: The oxidative coupling of 2,6-di-t-butylphenol under mild reaction conditions is well documented and the subject of many patents. However, the coupling of other monoand di- substituted phenols is not as well documented and thus there is scope for further investigation for providing a convenient, environmentally friendly and economically viable method for the oxidative coupling of these phenols. In this study, the oxidative coupling of a variety of alkylated phenolic substrates, 2-tbutylphenol, 2,6-di-t-butylphenol, 2,4 -di-t-butylphenol and ,4-dimethylphenol, using a range of different oxidizing agents, were investigated by means of experimental and/or theoretical means. The dibutylated aromatics provided the highest selectivities to their respective coupled products, with results obtained with the dimethyl analogue being only satisfactory, and that for 2 -t-butylphenol being totally inefficient. PM3 Molecular orbital (MO) calculations were used to predict the possible modes of coupling for the substrates 2,6 -di-t-butylphenol and 2,4-di-t-butylphenol, and these results were then compared with those obtained experimentally in the laboratory. Preliminarily, the coupling of unsubstituted phenolics was also assessed by means of MO calculations. Much emphasis was placed on Ce(IV) as the oxidant, and the reaction conditions under which it was used and the results that were obtained have not been reported before and are therefore novel. The oxidation of 2,4-di-t-butylphenol using Ce(IV) in the presence of methanesulphonic acid was optimized to afford high yields and selectivities to the desired ortho C-ortho C coupled product under mild reaction conditions. Various reaction parameters were also investigated in this case, such as varying the MeSO3H concentration, the solvent, the reaction temperature, the reaction time, the substrate loading, the rate of oxidant addition and the substrate to oxidant ratio. Ce(IV) also gave a high selectivity to the para C-para C coupled product when IX using 2,6-di-t-butylphenol as the substrate. However, it was not as effective with 2,4- dimethylphenol, and even less so with 2-t-butylphenol. The oxidation reactions of 2-t-butylphenol and 2,4-dimethylphenol with various coupling agents were also investigated with the intention of obtaining high selectivities to the respective desired coupled products. In these studies, 2-t-butylphenol afforded a large number of products, irrespective of the oxidant used. The dimethyl analogue was more selective, but results were not optimal. It was clear that the number of substituents on the phenol ring, their nature and their position with regards to the hydroxyl moiety was of great importance and made a significant impact on the preferred coupling mode of the substrate. It was observed that steric effects also played a major role in the outcome of these reactions: 2,6-di-t-butylphenol never afforded any C-O coupled products whereas 2-t-butylphenol, 2,4-di-t-butylphenol and 2,4-dimethylphenol all appeared to undergo some C-O coupling. Finally, reaction mechanisms were provided for both the K3Fe(CN)6 and Ce(IV) work, these reacting in basic and acidic media, respectively. It was proposed that both of these mechanisms operate through the initial formation of the phenoxyl radical.
- Full Text:
- Date Issued: 2005
Developing strategies for creating an environmental focus in a school: narrating the change process
- Authors: Hope, Megan Samantha
- Date: 2005
- Subjects: Environmental education Educational change School environment
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1946 , http://hdl.handle.net/10962/d1008093
- Description: Effective environmental education goes beyond raising environmental awareness and developing positive environmental values, to the encouragement of personal responsibility and action in response to contextual environmental issues in particular. The whole school approach has been advocated as the best approach to environmental education, based on the assumption that the values and attitudes espoused in the classroom need to be reflected in the day-to-day school practice. By practising what they teach, schools reinforce values with action. In contrast, inconsistencies between the formal and non-formal curriculum may lead young people to question the integrity of their teachers or condition them to accept such inconsistencies as cultural and social norms, which in turn may lead to apathy about the environment. Adjustments to the ethos of a school to foreground the environment, both within the curriculum , the management of the school and the behaviour of teachers, pupils and support staff, is not a straightforward undertaking. Institutional factors influence the change process in schools and each school presents a unique context. It is, therefore, difficult to develop a general strategy for the evolution of an environmental ethos. This case study narrates an attempt to implement a change towards an improved environmental focus in a school, and focuses on developing an understanding of how available resources can assist this process while engaging with complexity of change.
- Full Text:
- Date Issued: 2005
- Authors: Hope, Megan Samantha
- Date: 2005
- Subjects: Environmental education Educational change School environment
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1946 , http://hdl.handle.net/10962/d1008093
- Description: Effective environmental education goes beyond raising environmental awareness and developing positive environmental values, to the encouragement of personal responsibility and action in response to contextual environmental issues in particular. The whole school approach has been advocated as the best approach to environmental education, based on the assumption that the values and attitudes espoused in the classroom need to be reflected in the day-to-day school practice. By practising what they teach, schools reinforce values with action. In contrast, inconsistencies between the formal and non-formal curriculum may lead young people to question the integrity of their teachers or condition them to accept such inconsistencies as cultural and social norms, which in turn may lead to apathy about the environment. Adjustments to the ethos of a school to foreground the environment, both within the curriculum , the management of the school and the behaviour of teachers, pupils and support staff, is not a straightforward undertaking. Institutional factors influence the change process in schools and each school presents a unique context. It is, therefore, difficult to develop a general strategy for the evolution of an environmental ethos. This case study narrates an attempt to implement a change towards an improved environmental focus in a school, and focuses on developing an understanding of how available resources can assist this process while engaging with complexity of change.
- Full Text:
- Date Issued: 2005
Phylogeography and comparative ecophysiology of Chrysanthemoides Turn. Ex Medik. (Tribe Calenduleae)
- Authors: Howis, Seranne
- Date: 2005
- Subjects: Chrysanthemoides , Phylogeny , Ecophysiology , DNA , Plant genetics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4256 , http://hdl.handle.net/10962/d1008189
- Description: Chrysanthem Oides is a common Southern African shrub that grows in a variety of habitats. From coastal shrubland and fynbos to mountainous areas as far north as Kenya. The genus has two species and 8 subspecies. The diagnoses and delimitation of which have been based almost exclusively on morphological characteristics. This project aims to investigate, with the use of phylogenetic species concepts. The validity of these subspecies. Unlike biological species concepts that rely on reproductive isolation as a defining character of a species. Phylogenetic species concepts (PSC) are concerned with delimiting evolutionary significant units (ESUs). ESUs are evolutionarily isolated lineages, and under the PSC a species is an aggregation of organisms consistently diagnosable by a fixed character or combination of characters. This project therefore searched for genetic and physiological characters by which to delimit ESUs within the Cill), samhemoides genus. DNA sequencing was used to investigate the genetic characters, while gas exchange studies were used to investigate the ecophysiological characters. DNA sequence analysis indicated that the ESUs can be diagnosed by genetic means and that one species may be of hybrid origin. Field studies of three disparate genetically identifiable ESUs from three disparate climates found that there are noticeable differences in ecophysiological responses of these ESUs in the field. Plants from each ESU were transferred to a greenhouse and grown under identical conditions for several months and compared to determine if these traits are inherent, or elastic in relation to environmental conditions. Under simulated high rainfall conditions. There does not appear to be a significant difference in the photosynthetic traits.
- Full Text:
- Date Issued: 2005
Phylogeography and comparative ecophysiology of Chrysanthemoides Turn. Ex Medik. (Tribe Calenduleae)
- Authors: Howis, Seranne
- Date: 2005
- Subjects: Chrysanthemoides , Phylogeny , Ecophysiology , DNA , Plant genetics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4256 , http://hdl.handle.net/10962/d1008189
- Description: Chrysanthem Oides is a common Southern African shrub that grows in a variety of habitats. From coastal shrubland and fynbos to mountainous areas as far north as Kenya. The genus has two species and 8 subspecies. The diagnoses and delimitation of which have been based almost exclusively on morphological characteristics. This project aims to investigate, with the use of phylogenetic species concepts. The validity of these subspecies. Unlike biological species concepts that rely on reproductive isolation as a defining character of a species. Phylogenetic species concepts (PSC) are concerned with delimiting evolutionary significant units (ESUs). ESUs are evolutionarily isolated lineages, and under the PSC a species is an aggregation of organisms consistently diagnosable by a fixed character or combination of characters. This project therefore searched for genetic and physiological characters by which to delimit ESUs within the Cill), samhemoides genus. DNA sequencing was used to investigate the genetic characters, while gas exchange studies were used to investigate the ecophysiological characters. DNA sequence analysis indicated that the ESUs can be diagnosed by genetic means and that one species may be of hybrid origin. Field studies of three disparate genetically identifiable ESUs from three disparate climates found that there are noticeable differences in ecophysiological responses of these ESUs in the field. Plants from each ESU were transferred to a greenhouse and grown under identical conditions for several months and compared to determine if these traits are inherent, or elastic in relation to environmental conditions. Under simulated high rainfall conditions. There does not appear to be a significant difference in the photosynthetic traits.
- Full Text:
- Date Issued: 2005
An investigation into the pharmacological properties of propolis
- Authors: Hu, Fuliang
- Date: 2005
- Subjects: Propolis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5831 , http://hdl.handle.net/10962/d1007955
- Description: Propolis is a traditional value-added product from beekeeping, and has been widely used in medicine and the chemical industry because of its extensive biological activities. In this dissertation some pharmacological properties of propolis extracted by ethanol (EEP) and water (WSP) were studied by means of modem pharmacological methods. The results of the experiments show the following: 1. Both EEP and WSD led to decreased levels of fasting blood glucose (FBG), glycosylated haemoglobin (HBA1c), Fructosamine (FRU), blood urea nitrogen (BUN), uric acid (UA), malonaldehyde (MDA), nitric oxide (NO), nitric oxide synthetase (NOS), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and very-low density lipoprotein cholesterol (VLDL-C) in the serum of fasting rats; and, to increased serum levels of high-density lipoprotein cholesterol (HDL-C) and superoxide dismutase (SOD) in rats with diabetes mellitus. This suggests that propolis can control blood glucose and modulate the metabolism of glucose, blood lipid and protein, leading to decreased outputs of lipid peroxidation and scavenging free radicals in rats with diabetes mellitus. 2. Both EEP and WSD showed inhibitory effects on swelling induced by Freund's complete adjuvant and decreased the degree of local inflammatory responses; significantly inhibited the increase of interleukin-6 (lL-6) in inflamed tissues, but had no significant effect on levels of interleukin-2 (IL-2) and interferon-y (IFN-y). The results are consistent with the interpretation that EEP and WSD may exert these effects by inhibiting the activation and differentiation of mononuclear macrophages. 3. Both EEP and WSD exhibited significant anti-inflammatory effects in animal models with respect to thoracic capillary vessel leakage in mice, Carrageenan-induced oedema, Carrageen-aninduced pleurisy and acute lung damage in rats. The mechanisms for the anti-inflammatory effects probably involve decreasing prostaglandin and NO levels. 4. Both EEP and WSD had an inhibitory effect on the level of TG, TC, LDL-C, glutamic-pyruvic transaminase (GPT) and glutamic-oxalacetic transaminase (GOT) in serum, and TC, TG and MDA in liver of hyperlipidemic SD rats; but were without effects on HDL-C, MDA, SOD and NO in serum. EEP also reduced body weight, liver weight and liver index, but WSD did not reduce those indexes. The results showed that the two extracts contribute to the improvement of lipid metabolism in hyperlipidemic rats and provide them with the required anti-oxidative activity. 5. The 80% ethanol extracts of propolis had the highest flavonoid content. The flavone content of water extracts of propolis were obtained with a natural surface-active agent, under ultrasonic perturbation at 80°C, for 12 h and was 6.7 times greater than that of propolis extracted with water at room temperature. Compared to EEP, WSD has the same or a greater anti-tumor or anti-inflammation effect at the same dosage, and shows considerable pharmacological potential especially because of its low side effects and ease of preparation.
- Full Text:
- Date Issued: 2005
- Authors: Hu, Fuliang
- Date: 2005
- Subjects: Propolis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5831 , http://hdl.handle.net/10962/d1007955
- Description: Propolis is a traditional value-added product from beekeeping, and has been widely used in medicine and the chemical industry because of its extensive biological activities. In this dissertation some pharmacological properties of propolis extracted by ethanol (EEP) and water (WSP) were studied by means of modem pharmacological methods. The results of the experiments show the following: 1. Both EEP and WSD led to decreased levels of fasting blood glucose (FBG), glycosylated haemoglobin (HBA1c), Fructosamine (FRU), blood urea nitrogen (BUN), uric acid (UA), malonaldehyde (MDA), nitric oxide (NO), nitric oxide synthetase (NOS), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and very-low density lipoprotein cholesterol (VLDL-C) in the serum of fasting rats; and, to increased serum levels of high-density lipoprotein cholesterol (HDL-C) and superoxide dismutase (SOD) in rats with diabetes mellitus. This suggests that propolis can control blood glucose and modulate the metabolism of glucose, blood lipid and protein, leading to decreased outputs of lipid peroxidation and scavenging free radicals in rats with diabetes mellitus. 2. Both EEP and WSD showed inhibitory effects on swelling induced by Freund's complete adjuvant and decreased the degree of local inflammatory responses; significantly inhibited the increase of interleukin-6 (lL-6) in inflamed tissues, but had no significant effect on levels of interleukin-2 (IL-2) and interferon-y (IFN-y). The results are consistent with the interpretation that EEP and WSD may exert these effects by inhibiting the activation and differentiation of mononuclear macrophages. 3. Both EEP and WSD exhibited significant anti-inflammatory effects in animal models with respect to thoracic capillary vessel leakage in mice, Carrageenan-induced oedema, Carrageen-aninduced pleurisy and acute lung damage in rats. The mechanisms for the anti-inflammatory effects probably involve decreasing prostaglandin and NO levels. 4. Both EEP and WSD had an inhibitory effect on the level of TG, TC, LDL-C, glutamic-pyruvic transaminase (GPT) and glutamic-oxalacetic transaminase (GOT) in serum, and TC, TG and MDA in liver of hyperlipidemic SD rats; but were without effects on HDL-C, MDA, SOD and NO in serum. EEP also reduced body weight, liver weight and liver index, but WSD did not reduce those indexes. The results showed that the two extracts contribute to the improvement of lipid metabolism in hyperlipidemic rats and provide them with the required anti-oxidative activity. 5. The 80% ethanol extracts of propolis had the highest flavonoid content. The flavone content of water extracts of propolis were obtained with a natural surface-active agent, under ultrasonic perturbation at 80°C, for 12 h and was 6.7 times greater than that of propolis extracted with water at room temperature. Compared to EEP, WSD has the same or a greater anti-tumor or anti-inflammation effect at the same dosage, and shows considerable pharmacological potential especially because of its low side effects and ease of preparation.
- Full Text:
- Date Issued: 2005
Brand awareness of students at the Nelson Mandela Metropolitan University
- Authors: Huang, Wei
- Date: 2005
- Subjects: Brand name products , Brand choice , Consumers' preferences , Nelson Mandela Metropolitan University -- Students -- Attitudes
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9350 , http://hdl.handle.net/10948/187 , Brand name products , Brand choice , Consumers' preferences , Nelson Mandela Metropolitan University -- Students -- Attitudes
- Description: To ensure a long-term successful product brand, it is important to build brand awareness, to reach the consumer’s mind, encourage a consumer to develop a preference and eventually provide a positive contribution to consumer decision-making. Therefore, there is a need to understand and identify the role of brand awareness in the purchase process. An understanding of students as consumers and their brand awareness is important to marketers, particularly as students are recognised as a specialised market segment for a variety of products. The research focused on identifying the differences, if any, in brand awareness and its role in students’ purchase of sportswear clothing and sportswear shoes (high-involvement products) and coffee (a low-involvement product). A drop-off survey was used to collect the required empirical data from a convenience sample of 450 students enrolled at the Nelson Mandela Metropolitan University. The empirical findings showed that students were more aware of sportswear clothing and shoe brands than of coffee brands. Advertising played an important role in the awareness of sportswear shoes and clothing brands, but seemed unimportant in the case of coffee. Brand elements were found to enhance brand awareness. The brand name was important for coffee, while the name and the logo played a role in students’ awareness of sportswear brands. The study deduced that differences in brand awareness between high-involvement and low-involvement products exist among the students. Marketers thus need to choose appropriate strategies to create and increase brand awareness for the different products.
- Full Text:
- Date Issued: 2005
- Authors: Huang, Wei
- Date: 2005
- Subjects: Brand name products , Brand choice , Consumers' preferences , Nelson Mandela Metropolitan University -- Students -- Attitudes
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9350 , http://hdl.handle.net/10948/187 , Brand name products , Brand choice , Consumers' preferences , Nelson Mandela Metropolitan University -- Students -- Attitudes
- Description: To ensure a long-term successful product brand, it is important to build brand awareness, to reach the consumer’s mind, encourage a consumer to develop a preference and eventually provide a positive contribution to consumer decision-making. Therefore, there is a need to understand and identify the role of brand awareness in the purchase process. An understanding of students as consumers and their brand awareness is important to marketers, particularly as students are recognised as a specialised market segment for a variety of products. The research focused on identifying the differences, if any, in brand awareness and its role in students’ purchase of sportswear clothing and sportswear shoes (high-involvement products) and coffee (a low-involvement product). A drop-off survey was used to collect the required empirical data from a convenience sample of 450 students enrolled at the Nelson Mandela Metropolitan University. The empirical findings showed that students were more aware of sportswear clothing and shoe brands than of coffee brands. Advertising played an important role in the awareness of sportswear shoes and clothing brands, but seemed unimportant in the case of coffee. Brand elements were found to enhance brand awareness. The brand name was important for coffee, while the name and the logo played a role in students’ awareness of sportswear brands. The study deduced that differences in brand awareness between high-involvement and low-involvement products exist among the students. Marketers thus need to choose appropriate strategies to create and increase brand awareness for the different products.
- Full Text:
- Date Issued: 2005
Investigating call control using MGCP in conjuction with SIP and H.323
- Authors: Jacobs, Ashley
- Date: 2005 , 2005-03-14
- Subjects: Communication -- Technological innovations , Digital telephone systems , Computer networks , Computer network protocols , Internet telephony
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4631 , http://hdl.handle.net/10962/d1006516 , Communication -- Technological innovations , Digital telephone systems , Computer networks , Computer network protocols , Internet telephony
- Description: Telephony used to mean using a telephone to call another telephone on the Public Switched Telephone Network (PSTN), and data networks were used purely to allow computers to communicate. However, with the advent of the Internet, telephony services have been extended to run on data networks. Telephone calls within the IP network are known as Voice over IP. These calls are carried by a number of protocols, with the most popular ones currently being Session Initiation Protocol (SIP) and H.323. Calls can be made from the IP network to the PSTN and vice versa through the use of a gateway. The gateway translates the packets from the IP network to circuits on the PSTN and vice versa to facilitate calls between the two networks. Gateways have evolved and are now split into two entities using the master/slave architecture. The master is an intelligent Media Gateway Controller (MGC) that handles the call control and signalling. The slave is a "dumb" Media Gateway (MG) that handles the translation of the media. The current gateway control protocols in use are Megaco/H.248, MGCP and Skinny. These protocols have proved themselves on the edge of the network. Furthermore, since they communicate with the call signalling VoIP protocols as well as the PSTN, they have to be the lingua franca between the two networks. Within the VoIP network, the numbers of call signalling protocols make it difficult to communicate with each other and to create services. This research investigates the use of Gateway Control Protocols as the lowest common denominator between the call signalling protocols SIP and H.323. More specifically, it uses MGCP to investigate service creation. It also considers the use of MGCP as a protocol translator between SIP and H.323. A service was created using MGCP to allow H.323 endpoints to send Short Message Service (SMS) messages. This service was then extended with minimal effort to SIP endpoints. This service investigated MGCP’s ability to handle call control from the H.323 and SIP endpoints. An MGC was then successfully used to perform as a protocol translator between SIP and H.323.
- Full Text:
- Date Issued: 2005
- Authors: Jacobs, Ashley
- Date: 2005 , 2005-03-14
- Subjects: Communication -- Technological innovations , Digital telephone systems , Computer networks , Computer network protocols , Internet telephony
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4631 , http://hdl.handle.net/10962/d1006516 , Communication -- Technological innovations , Digital telephone systems , Computer networks , Computer network protocols , Internet telephony
- Description: Telephony used to mean using a telephone to call another telephone on the Public Switched Telephone Network (PSTN), and data networks were used purely to allow computers to communicate. However, with the advent of the Internet, telephony services have been extended to run on data networks. Telephone calls within the IP network are known as Voice over IP. These calls are carried by a number of protocols, with the most popular ones currently being Session Initiation Protocol (SIP) and H.323. Calls can be made from the IP network to the PSTN and vice versa through the use of a gateway. The gateway translates the packets from the IP network to circuits on the PSTN and vice versa to facilitate calls between the two networks. Gateways have evolved and are now split into two entities using the master/slave architecture. The master is an intelligent Media Gateway Controller (MGC) that handles the call control and signalling. The slave is a "dumb" Media Gateway (MG) that handles the translation of the media. The current gateway control protocols in use are Megaco/H.248, MGCP and Skinny. These protocols have proved themselves on the edge of the network. Furthermore, since they communicate with the call signalling VoIP protocols as well as the PSTN, they have to be the lingua franca between the two networks. Within the VoIP network, the numbers of call signalling protocols make it difficult to communicate with each other and to create services. This research investigates the use of Gateway Control Protocols as the lowest common denominator between the call signalling protocols SIP and H.323. More specifically, it uses MGCP to investigate service creation. It also considers the use of MGCP as a protocol translator between SIP and H.323. A service was created using MGCP to allow H.323 endpoints to send Short Message Service (SMS) messages. This service was then extended with minimal effort to SIP endpoints. This service investigated MGCP’s ability to handle call control from the H.323 and SIP endpoints. An MGC was then successfully used to perform as a protocol translator between SIP and H.323.
- Full Text:
- Date Issued: 2005
An investigation into improved ionospheric F1 layer predictions over Grahamstown, South Africa
- Authors: Jacobs, Linda
- Date: 2005
- Subjects: Ionosphere , Ionospheric electron density -- South Africa -- Grahamstown , Neural networks (Computer Science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5511 , http://hdl.handle.net/10962/d1008094 , Ionosphere , Ionospheric electron density -- South Africa -- Grahamstown , Neural networks (Computer Science)
- Description: This thesis describes an analysis of the F1 layer data obtained from the Grahamstown (33.32°S, 26.500 E), South Africa ionospheric station and the use of this data in improving a Neural Network (NN) based model of the F1 layer of the ionosphere. An application for real-time ray tracing through the South African ionosphere was identified, and for this application real-time evaluation of the electron density profile is essential. Raw real-time virtual height data are provided by a Lowell Digisonde (DPS), which employs the automatic scaling software, ARTIST whose output includes the virtual-toreal height data conversion. Experience has shown that there are times when the ray tracing performance is degraded because of difficulties surrounding the real-time characterization of the F1 region by ARTIST. Therefore available DPS data from the archives of the Grahamstown station were re-scaled manually in order to establish the extent of the problem and the times and conditions under which most inaccuracies occur. The re-scaled data were used to update the F1 contribution of an existing NN based ionospheric model, the LAM model, which predicts the values of the parameters required to produce an electron density profile. This thesis describes the development of three separate NNs required to predict the ionospheric characteristics and coefficients that are required to describe the F1 layer profile. Inputs to the NNs include day number, hour and measures of solar and magnetic activity. Outputs include the value of the critical frequency of the F1 layer, foF1, the real height of reflection at the peak, hmFl, as well as information on the state of the F1 layer. All data from the Grahamstown station from 1973 to 2003 was used to train these NNs. Tests show that the predictive ability of the LAM model has been improved by incorporating the re-scaled data.
- Full Text:
- Date Issued: 2005
- Authors: Jacobs, Linda
- Date: 2005
- Subjects: Ionosphere , Ionospheric electron density -- South Africa -- Grahamstown , Neural networks (Computer Science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5511 , http://hdl.handle.net/10962/d1008094 , Ionosphere , Ionospheric electron density -- South Africa -- Grahamstown , Neural networks (Computer Science)
- Description: This thesis describes an analysis of the F1 layer data obtained from the Grahamstown (33.32°S, 26.500 E), South Africa ionospheric station and the use of this data in improving a Neural Network (NN) based model of the F1 layer of the ionosphere. An application for real-time ray tracing through the South African ionosphere was identified, and for this application real-time evaluation of the electron density profile is essential. Raw real-time virtual height data are provided by a Lowell Digisonde (DPS), which employs the automatic scaling software, ARTIST whose output includes the virtual-toreal height data conversion. Experience has shown that there are times when the ray tracing performance is degraded because of difficulties surrounding the real-time characterization of the F1 region by ARTIST. Therefore available DPS data from the archives of the Grahamstown station were re-scaled manually in order to establish the extent of the problem and the times and conditions under which most inaccuracies occur. The re-scaled data were used to update the F1 contribution of an existing NN based ionospheric model, the LAM model, which predicts the values of the parameters required to produce an electron density profile. This thesis describes the development of three separate NNs required to predict the ionospheric characteristics and coefficients that are required to describe the F1 layer profile. Inputs to the NNs include day number, hour and measures of solar and magnetic activity. Outputs include the value of the critical frequency of the F1 layer, foF1, the real height of reflection at the peak, hmFl, as well as information on the state of the F1 layer. All data from the Grahamstown station from 1973 to 2003 was used to train these NNs. Tests show that the predictive ability of the LAM model has been improved by incorporating the re-scaled data.
- Full Text:
- Date Issued: 2005
The effect of personalised adjustments to computer workstations on the efficiency and physical comfort of computer operators
- Authors: James, Genevieve
- Date: 2005
- Subjects: Human engineering , Engineering design , Work environment , Microcomputer workstations -- Health aspects , Occupational diseases -- Prevention
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5112 , http://hdl.handle.net/10962/d1005190 , Human engineering , Engineering design , Work environment , Microcomputer workstations -- Health aspects , Occupational diseases -- Prevention
- Description: The present study sought to investigate the effects of a Standard workstation, designed for “average” users, on an anthropometrically diverse sample of computer operators, and to assess whether physical and perceptual responses, as well as performance efficiency were dependent on stature. Further investigation assessed the influence of personalised adjustments to the Standard workstation, based on the anthropometric characteristics of the subjects, as well as the introduction of a custom-designed ‘floating’ wrist support, on subject responses. All subjects (n=30) were tested in each of the three workstations: Standard, Personalised and Wrist Support. For analysis of responses in the Standard workstation, subjects were divided into three groups depending on their stature: Short (<1650mm), Medium (1650mm to 1800mm), Tall (>1800mm). The musculoskeletal responses indicated that Tall subjects were forced to adopt the most awkward general body postures as a result of the low computer screen. However, the low screen allowed for the Short subjects to adopt the most natural general body postures, although levels of muscular activity in the upper trapezius suggest that the muscular load imposed on both Short and Tall subjects was significantly greater than that imposed on the Medium subjects. In addition, the Medium subjects’ perceptions of the Standard workstation dimensions support the fact that this workstation was better suited to users with “average” morphologies. The responses elicited in the Personalised and Wrist Support workstations were improved significantly when compared to the Standard workstation. Joint angles were more natural, upper trapezius EMG was reduced, standard of performance improved and perceptual responses indicated a diminished incidence of body and visual discomfort, as well as greater perceived satisfaction with these workstation dimensions. The improved physical responses suggest a decrease in the risk of developing cumulative trauma disorders. Although subjects were unaccustomed to the wrist support device, this workstation demonstrated a further reduction in the range of wrist angles, as well as a general positive attitude towards the concept.
- Full Text:
- Date Issued: 2005
- Authors: James, Genevieve
- Date: 2005
- Subjects: Human engineering , Engineering design , Work environment , Microcomputer workstations -- Health aspects , Occupational diseases -- Prevention
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5112 , http://hdl.handle.net/10962/d1005190 , Human engineering , Engineering design , Work environment , Microcomputer workstations -- Health aspects , Occupational diseases -- Prevention
- Description: The present study sought to investigate the effects of a Standard workstation, designed for “average” users, on an anthropometrically diverse sample of computer operators, and to assess whether physical and perceptual responses, as well as performance efficiency were dependent on stature. Further investigation assessed the influence of personalised adjustments to the Standard workstation, based on the anthropometric characteristics of the subjects, as well as the introduction of a custom-designed ‘floating’ wrist support, on subject responses. All subjects (n=30) were tested in each of the three workstations: Standard, Personalised and Wrist Support. For analysis of responses in the Standard workstation, subjects were divided into three groups depending on their stature: Short (<1650mm), Medium (1650mm to 1800mm), Tall (>1800mm). The musculoskeletal responses indicated that Tall subjects were forced to adopt the most awkward general body postures as a result of the low computer screen. However, the low screen allowed for the Short subjects to adopt the most natural general body postures, although levels of muscular activity in the upper trapezius suggest that the muscular load imposed on both Short and Tall subjects was significantly greater than that imposed on the Medium subjects. In addition, the Medium subjects’ perceptions of the Standard workstation dimensions support the fact that this workstation was better suited to users with “average” morphologies. The responses elicited in the Personalised and Wrist Support workstations were improved significantly when compared to the Standard workstation. Joint angles were more natural, upper trapezius EMG was reduced, standard of performance improved and perceptual responses indicated a diminished incidence of body and visual discomfort, as well as greater perceived satisfaction with these workstation dimensions. The improved physical responses suggest a decrease in the risk of developing cumulative trauma disorders. Although subjects were unaccustomed to the wrist support device, this workstation demonstrated a further reduction in the range of wrist angles, as well as a general positive attitude towards the concept.
- Full Text:
- Date Issued: 2005
On the growth and characterisation of AIGaN alloys for optoelectronic applications
- Authors: James, Grant Robert
- Date: 2005
- Subjects: Gallium nitride -- Electric properties , Photoluminescence
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/8824 , vital:26433
- Description: In this study the growth and characterisation of undoped and Si-doped AlxGa1-xN has been performed. The layers were grown using low-pressure metalorganic vapour phase deposition (MOCVD) on sapphire substrates. The optical and electrical properties of the AlxGa1-xN layers were studied using variable temperature Hall effect and photoluminescence measurements. AlxGa1-xN layers were grown over the entire composition range. Room temperature ultraviolet (UV) transmission measurements showed that the material quality was very good for layers with an Al content, x, of 0 _ x _ 0.5. However, the quality of layers of higher composition was seen to rapidly decrease with increasing x. The electrical and optical properties of AlxGa1-xN with x < 0.5 were also good, comparable to those reported on in literature. The study of the Si-doping of AlxGa1-xN was performed in two parts; firstly a series of Al0.23Ga0.77N samples was grown in which the doping level was increased from zero to n _ 3 × 1018 cm-3. A similar, albeit a less rigorous, study was performed for Al0.41Ga0.59N and Al0.5Ga0.5N. A second series of samples was then grown in which the doping level was kept constant, while the Al content was incrementally increased. Room temperature Hall effect measurements performed on Si-doped Al0.23Ga0.77N showed that the electron concentration did not scale linearly with the silane flow, as was the case in GaN. It was also seen that the electron mobility of the layers increased with slight Si-doping, possibly due to an improvement in the crystalline quality and/or a change in the conduction mechanism. It was also found that at higher compositions (x = 0.41 and 0.50) an increase in the doping level resulted in an increase in the mobility. Variable temperature Hall effect and photoluminescence measurements, performed on the Al0.23Ga0.77N samples, revealed a good correlation between the first PL activation energy E1 and the donor activation energy ED, prompting the conclusion that the first PL recombination channel in AlxGa1-xN is due to the delocalisation of excitons bound at neutral Si donors. Furthermore, E1 and ED were seen to decrease with n1/3, as is the case for GaN and other semiconductor materials. It was also observed that strong exciton localisation occurs in slightly Si-doped material, with the amount of localization becoming less at higher doping levels. Possible mechanisms responsible for the second PL recombination channel of activation energy E2 were also proposed. The electrical and optical properties of the second set of AlxGa1-xN samples was then studied. The PL properties of undoped AlxGa1-xN were typical of a homogeneous alloy system, with the increase in the PL FWHM and exciton localisation energies with x following the trend predicted by alloy disorder theory. The variation of the band gap energy with the Al content could not, however, be fitted over the entire composition range using a single bowing parameter. It was proposed that this was due either to an effect of the 9 7 valence band crossover, or due to exciton localisation at alloy disorder and/or impurities. As was the case for GaN and Al0.23Ga0.77N, all undoped material was highly resistive. As was mentioned earlier, the exciton localisation energies increased according to alloy disorder theory in undoped AlxGa1-xN. In the doped samples, however, a large increase in the donor localisation energy was measured for x > 0.3. The possibility that Si could become a DX-centre in AlxGa1-xN was then investigated. However, Hall effect measurements showed that the Si activation energy increased in good agreement with the model of a shallow effective mass state donor, with no sudden increase in ED being observed up to x = 0.4. It was then suggested that the increase in the E1 and E2 activation energies, as well as the exciton localisation energies, could be due to the 9 7 valence band crossover, which occurs at roughly the same composition. However, due to the scarcity of reports on the valence band structure in AlxGa1-xN no conclusions could be made at this stage as to the effect of the 9 7 valence band crossover on the PL properties of AlxGa1-xN.
- Full Text:
- Date Issued: 2005
- Authors: James, Grant Robert
- Date: 2005
- Subjects: Gallium nitride -- Electric properties , Photoluminescence
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/8824 , vital:26433
- Description: In this study the growth and characterisation of undoped and Si-doped AlxGa1-xN has been performed. The layers were grown using low-pressure metalorganic vapour phase deposition (MOCVD) on sapphire substrates. The optical and electrical properties of the AlxGa1-xN layers were studied using variable temperature Hall effect and photoluminescence measurements. AlxGa1-xN layers were grown over the entire composition range. Room temperature ultraviolet (UV) transmission measurements showed that the material quality was very good for layers with an Al content, x, of 0 _ x _ 0.5. However, the quality of layers of higher composition was seen to rapidly decrease with increasing x. The electrical and optical properties of AlxGa1-xN with x < 0.5 were also good, comparable to those reported on in literature. The study of the Si-doping of AlxGa1-xN was performed in two parts; firstly a series of Al0.23Ga0.77N samples was grown in which the doping level was increased from zero to n _ 3 × 1018 cm-3. A similar, albeit a less rigorous, study was performed for Al0.41Ga0.59N and Al0.5Ga0.5N. A second series of samples was then grown in which the doping level was kept constant, while the Al content was incrementally increased. Room temperature Hall effect measurements performed on Si-doped Al0.23Ga0.77N showed that the electron concentration did not scale linearly with the silane flow, as was the case in GaN. It was also seen that the electron mobility of the layers increased with slight Si-doping, possibly due to an improvement in the crystalline quality and/or a change in the conduction mechanism. It was also found that at higher compositions (x = 0.41 and 0.50) an increase in the doping level resulted in an increase in the mobility. Variable temperature Hall effect and photoluminescence measurements, performed on the Al0.23Ga0.77N samples, revealed a good correlation between the first PL activation energy E1 and the donor activation energy ED, prompting the conclusion that the first PL recombination channel in AlxGa1-xN is due to the delocalisation of excitons bound at neutral Si donors. Furthermore, E1 and ED were seen to decrease with n1/3, as is the case for GaN and other semiconductor materials. It was also observed that strong exciton localisation occurs in slightly Si-doped material, with the amount of localization becoming less at higher doping levels. Possible mechanisms responsible for the second PL recombination channel of activation energy E2 were also proposed. The electrical and optical properties of the second set of AlxGa1-xN samples was then studied. The PL properties of undoped AlxGa1-xN were typical of a homogeneous alloy system, with the increase in the PL FWHM and exciton localisation energies with x following the trend predicted by alloy disorder theory. The variation of the band gap energy with the Al content could not, however, be fitted over the entire composition range using a single bowing parameter. It was proposed that this was due either to an effect of the 9 7 valence band crossover, or due to exciton localisation at alloy disorder and/or impurities. As was the case for GaN and Al0.23Ga0.77N, all undoped material was highly resistive. As was mentioned earlier, the exciton localisation energies increased according to alloy disorder theory in undoped AlxGa1-xN. In the doped samples, however, a large increase in the donor localisation energy was measured for x > 0.3. The possibility that Si could become a DX-centre in AlxGa1-xN was then investigated. However, Hall effect measurements showed that the Si activation energy increased in good agreement with the model of a shallow effective mass state donor, with no sudden increase in ED being observed up to x = 0.4. It was then suggested that the increase in the E1 and E2 activation energies, as well as the exciton localisation energies, could be due to the 9 7 valence band crossover, which occurs at roughly the same composition. However, due to the scarcity of reports on the valence band structure in AlxGa1-xN no conclusions could be made at this stage as to the effect of the 9 7 valence band crossover on the PL properties of AlxGa1-xN.
- Full Text:
- Date Issued: 2005
An investigation of female leaders' perceptions of organisational culture and leadership in a Catholic High School
- Jean-Louis, Lily-Claire Virginie
- Authors: Jean-Louis, Lily-Claire Virginie
- Date: 2005
- Subjects: Catholic schools -- South Africa -- Administration School management and organization -- South Africa Educational leadership -- South Africa Corporate culture -- South Africa Women school administrators -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1625 , http://hdl.handle.net/10962/d1003507
- Description: For the past thirty years, leadership theories have focused on the importance of the individual within the school organisation. The shared assumptions and beliefs of the individuals working in the same organisation shape the school’s organisational culture, and organisational culture is a salient factor which should be considered when understanding educational leadership. The focus of my study is to explore the relationship between organisational culture and leadership. In the same context, new approaches to the study of leadership have explored the issue of gender in leadership. Female leadership studies - the second focus of this study - seek not only to restore the place of the individual but also argue a place for women in educational leadership. Based in the interpretive paradigm, this is a case study of a Catholic all-girl secondary school called the Loreto Convent School of Pretoria. Historically, the Loreto schools have aimed at promoting and empowering girls’ education and female leadership. It was therefore an appropriate site in which to explore organisational culture and its relationship with leadership, particularly female leadership. I purposefully chose three of the school’s female leaders - the school’s principal, the High school Head of Department and the High school head girl - focusing on their perceptions and experiences of their leadership and the school’s culture. My research findings show that an understanding of the relationship between organisational culture and leadership cannot be complete without acknowledging the importance of the leader as an individual, with his/her personal background and values, taking into account gender as well as the multiple roles that the individual has in society. Furthermore, the ‘humane’ characteristic of educational leadership leads to an understanding that the leader is often confronted with conflicting situations where he/she is caught between personal/organisational values and the need to achieve the task. Finally, my findings show that contemporary leaders are now called upon to work and participate in the promotion of social justice in order to fight against society’s socio-economic inequality and improve the quality of education and life.
- Full Text:
- Date Issued: 2005
- Authors: Jean-Louis, Lily-Claire Virginie
- Date: 2005
- Subjects: Catholic schools -- South Africa -- Administration School management and organization -- South Africa Educational leadership -- South Africa Corporate culture -- South Africa Women school administrators -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1625 , http://hdl.handle.net/10962/d1003507
- Description: For the past thirty years, leadership theories have focused on the importance of the individual within the school organisation. The shared assumptions and beliefs of the individuals working in the same organisation shape the school’s organisational culture, and organisational culture is a salient factor which should be considered when understanding educational leadership. The focus of my study is to explore the relationship between organisational culture and leadership. In the same context, new approaches to the study of leadership have explored the issue of gender in leadership. Female leadership studies - the second focus of this study - seek not only to restore the place of the individual but also argue a place for women in educational leadership. Based in the interpretive paradigm, this is a case study of a Catholic all-girl secondary school called the Loreto Convent School of Pretoria. Historically, the Loreto schools have aimed at promoting and empowering girls’ education and female leadership. It was therefore an appropriate site in which to explore organisational culture and its relationship with leadership, particularly female leadership. I purposefully chose three of the school’s female leaders - the school’s principal, the High school Head of Department and the High school head girl - focusing on their perceptions and experiences of their leadership and the school’s culture. My research findings show that an understanding of the relationship between organisational culture and leadership cannot be complete without acknowledging the importance of the leader as an individual, with his/her personal background and values, taking into account gender as well as the multiple roles that the individual has in society. Furthermore, the ‘humane’ characteristic of educational leadership leads to an understanding that the leader is often confronted with conflicting situations where he/she is caught between personal/organisational values and the need to achieve the task. Finally, my findings show that contemporary leaders are now called upon to work and participate in the promotion of social justice in order to fight against society’s socio-economic inequality and improve the quality of education and life.
- Full Text:
- Date Issued: 2005