Constituent processes of leaf senescence in Hordeum vulgare cv. Dyan
- Afitlhile, Meshack Mosimanegape
- Authors: Afitlhile, Meshack Mosimanegape
- Date: 1994
- Subjects: Leaves , Leaves -- Development
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4184 , http://hdl.handle.net/10962/d1003752
- Description: Changes in chlorophyll content, carotenoid content and composition, abscisic acid and phaseic acid levels, hydrolytic enzyme activity and polypeptide pattern were monitored during senescence of the primary attached leaves of Hordeum vulgare L. cv. Dyan. Senescence occurred due to the normal course of leaf development or was induced by incubation of leaves in darkness. Loss of chlorophyll and total leaf protein was retarded in light whereas it continued rapidly in leaves from dark-incubated seedlings. Chlorophyll alb ratio increased with the progression of senescence, suggesting that chlorophyll b was referentially degraded during this process. Loss of total protein coincided with enhanced activity of acid and neutral proteases. In contrast, loss of chlorophyll was not accompanied by an increase in· peroxidase activity, suggesting that this enzyme was not responsible for initiating chlorophyll breakdown. Carotenoid and abscisic acid levels were monitored in the same tissue extracts. The results obtained show that the increase in endogenous levels of abscisic acid, induced by senescence, correlated with enhanced epoxidation of the xanthophyll cycle, ie., increased conversion of zeaxanthin to antheraxanthin and all-trans-violaxanthin. In addition, an increase in abscisic acid levels occurred concomitant with a decrease in all-trans-violaxanthin and 9'-cis-neoxanthin, suggesting an apparent 1:1 relationship on a molar basis. It is therefore proposed that enhanced abscisic acid production, due to foliar senescence, arises from fluctuations in carotenoid turnover. Polypeptide patterns in isolated chloroplasts, purified thylakoid and stromal fractions were very similar for leaves incubated in either light or darkness. A decrease in intensity of bands was observed in isolated chloroplasts and stromal fractions. Intensity of bands in thylakoids remained unchanged with the progression of senescence. Protein standards of peroxidase and lipoxygenase co-migrated with proteins of the isolated chloroplast. Although tentative, some proteins of the chloroplast may be representative of precursors of hydrolytic enzymes which are known to increase during senescence.
- Full Text:
- Date Issued: 1994
- Authors: Afitlhile, Meshack Mosimanegape
- Date: 1994
- Subjects: Leaves , Leaves -- Development
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4184 , http://hdl.handle.net/10962/d1003752
- Description: Changes in chlorophyll content, carotenoid content and composition, abscisic acid and phaseic acid levels, hydrolytic enzyme activity and polypeptide pattern were monitored during senescence of the primary attached leaves of Hordeum vulgare L. cv. Dyan. Senescence occurred due to the normal course of leaf development or was induced by incubation of leaves in darkness. Loss of chlorophyll and total leaf protein was retarded in light whereas it continued rapidly in leaves from dark-incubated seedlings. Chlorophyll alb ratio increased with the progression of senescence, suggesting that chlorophyll b was referentially degraded during this process. Loss of total protein coincided with enhanced activity of acid and neutral proteases. In contrast, loss of chlorophyll was not accompanied by an increase in· peroxidase activity, suggesting that this enzyme was not responsible for initiating chlorophyll breakdown. Carotenoid and abscisic acid levels were monitored in the same tissue extracts. The results obtained show that the increase in endogenous levels of abscisic acid, induced by senescence, correlated with enhanced epoxidation of the xanthophyll cycle, ie., increased conversion of zeaxanthin to antheraxanthin and all-trans-violaxanthin. In addition, an increase in abscisic acid levels occurred concomitant with a decrease in all-trans-violaxanthin and 9'-cis-neoxanthin, suggesting an apparent 1:1 relationship on a molar basis. It is therefore proposed that enhanced abscisic acid production, due to foliar senescence, arises from fluctuations in carotenoid turnover. Polypeptide patterns in isolated chloroplasts, purified thylakoid and stromal fractions were very similar for leaves incubated in either light or darkness. A decrease in intensity of bands was observed in isolated chloroplasts and stromal fractions. Intensity of bands in thylakoids remained unchanged with the progression of senescence. Protein standards of peroxidase and lipoxygenase co-migrated with proteins of the isolated chloroplast. Although tentative, some proteins of the chloroplast may be representative of precursors of hydrolytic enzymes which are known to increase during senescence.
- Full Text:
- Date Issued: 1994
A basic guide to the Reconstruction and Development Programme
- Authors: African National Congress
- Date: 1994
- Subjects: Reconstruction and development programme (South Africa) , South Africa -- Economic policy , South Africa -- Social policy , African National Congress
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/75927 , vital:30483 , 1874902062
- Description: The RDP is a plan to address the many social and economic problems facing our country — problems such as...violence, lack of housing, lack of jobs, inadequate education and health care, lack of democracy, a failing economy. The RDP recognises that all of these problems are connected. For example, we cannot successfully build the economy while millions do not have homes or jobs. And we cannot provide homes and jobs without rebuilding the economy. We need policies and strategies to address all of the problems together. The RDP aims to do this. The RDP is a programme to mobilise all our people and all our resources to finally get rid of apartheid and build a democratic, non racial and non sexist future. The RDP was drawn up by the ANC-led alliance in consultation with other key mass organisations and assisted by a wide range of nongovernmental organisations (NGOs) and research organisations. This inclusive approach to developing and implementing policy — involving as many organisations as possible — is unique in South Africa’s political history. The ANC — because it is a liberation movement and based on the traditions of the Freedom Charter — is the only political organisation which can bring together such a wide range of social movements, community-based organisations and numerous other sectors and formations. This widespread and broad-based support throughout South Africa will allow the ANC within a Government of National Unity successfully to implement the RDP.
- Full Text:
- Date Issued: 1994
- Authors: African National Congress
- Date: 1994
- Subjects: Reconstruction and development programme (South Africa) , South Africa -- Economic policy , South Africa -- Social policy , African National Congress
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/75927 , vital:30483 , 1874902062
- Description: The RDP is a plan to address the many social and economic problems facing our country — problems such as...violence, lack of housing, lack of jobs, inadequate education and health care, lack of democracy, a failing economy. The RDP recognises that all of these problems are connected. For example, we cannot successfully build the economy while millions do not have homes or jobs. And we cannot provide homes and jobs without rebuilding the economy. We need policies and strategies to address all of the problems together. The RDP aims to do this. The RDP is a programme to mobilise all our people and all our resources to finally get rid of apartheid and build a democratic, non racial and non sexist future. The RDP was drawn up by the ANC-led alliance in consultation with other key mass organisations and assisted by a wide range of nongovernmental organisations (NGOs) and research organisations. This inclusive approach to developing and implementing policy — involving as many organisations as possible — is unique in South Africa’s political history. The ANC — because it is a liberation movement and based on the traditions of the Freedom Charter — is the only political organisation which can bring together such a wide range of social movements, community-based organisations and numerous other sectors and formations. This widespread and broad-based support throughout South Africa will allow the ANC within a Government of National Unity successfully to implement the RDP.
- Full Text:
- Date Issued: 1994
"We are all friends here": the social dynamics of a development project
- Authors: Ainslie, Andrew
- Date: 1994
- Subjects: St Mark's Mission (South Africa) St Mark's Community Project Rural development -- South Africa -- Eastern Cape Community development -- South Africa Cooperative marketing of agricultural produce -- South Africa Women in community development -- South Africa Women in cooperative societies -- South Africa Sex role in the work environment -- South Africa World Vision International Eastern Cape (South Africa) -- Rural conditions
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/1663 , vital:20214 , ISBN 0868102660
- Description: In 1978, a Rev. John Galela, then a minister at St.Mark's, launched a project which included pig-farming and the growing of vegetables for human consumption and to feed the pigs. With a grant from the South African Council of Churches (SACC), a pump was installed on the banks of the river and vegetables were grown under irrigation on 2,4 ha of land. This pilot project did not affect the leasing arrangements mentioned above. The project apparently enjoyed the approval and support of the local community, until the chief, Chief M.D. Feketha (an influential member of the Ciskeian cabinet at this time), came to hear of it and forbade the people of Newlands, who fall under his "tribal" jurisdiction, to participate in the project. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1994
- Authors: Ainslie, Andrew
- Date: 1994
- Subjects: St Mark's Mission (South Africa) St Mark's Community Project Rural development -- South Africa -- Eastern Cape Community development -- South Africa Cooperative marketing of agricultural produce -- South Africa Women in community development -- South Africa Women in cooperative societies -- South Africa Sex role in the work environment -- South Africa World Vision International Eastern Cape (South Africa) -- Rural conditions
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/1663 , vital:20214 , ISBN 0868102660
- Description: In 1978, a Rev. John Galela, then a minister at St.Mark's, launched a project which included pig-farming and the growing of vegetables for human consumption and to feed the pigs. With a grant from the South African Council of Churches (SACC), a pump was installed on the banks of the river and vegetables were grown under irrigation on 2,4 ha of land. This pilot project did not affect the leasing arrangements mentioned above. The project apparently enjoyed the approval and support of the local community, until the chief, Chief M.D. Feketha (an influential member of the Ciskeian cabinet at this time), came to hear of it and forbade the people of Newlands, who fall under his "tribal" jurisdiction, to participate in the project. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1994
An evaluation of the interdisciplinary nature of environmental education in colleges of education in Bophuthatswana
- Authors: Akwa, Joseph Yeboah
- Date: 1994
- Subjects: Environmental education -- South Africa -- Bophuthatswana Environmental education -- Curricula -- South Africa -- Bophuthatswana
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1526 , http://hdl.handle.net/10962/d1003408
- Description: This study was aimed at evaluating the interdisciplinary nature of environmental education within the colleges of education in Bophuthatswana. Data collection was based on semi-structured interviews with college lecturers and, to a lesser extent, on observations during a workshop with environmental educators from Bophuthatswana. Knowledge was gained about college related factors which influence the varying extent to which environmental education is being implemented within the colleges of education. Lecturers' understanding of the interdisciplinary nature of environmental education and related concepts was explored. Insights were also gained into problems of implementation which included lecturers' limited understanding of the concept of interdisciplinarity, structural ambiguities, limited training and experience, and a lack of clarity in both local and international literature on environmental education concepts and terms. Specifically the study sought to illuminate the dichotomy between theory and practice, the conflict between the dominant curriculum paradigm and the new emerging paradigm, and tensions between the interdisciplinary nature of environmental education and subject-based disciplines, which lead to problems of implementation. The study could make an important contribution to the current curriculum debate on environmental education in South Africa by illuminating the dichotomy between the theory and the practice of environmental education, and the problems involved in translating interdisciplinary approaches into workable classroom practices within discipline based curriculum structures.
- Full Text:
- Date Issued: 1994
- Authors: Akwa, Joseph Yeboah
- Date: 1994
- Subjects: Environmental education -- South Africa -- Bophuthatswana Environmental education -- Curricula -- South Africa -- Bophuthatswana
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1526 , http://hdl.handle.net/10962/d1003408
- Description: This study was aimed at evaluating the interdisciplinary nature of environmental education within the colleges of education in Bophuthatswana. Data collection was based on semi-structured interviews with college lecturers and, to a lesser extent, on observations during a workshop with environmental educators from Bophuthatswana. Knowledge was gained about college related factors which influence the varying extent to which environmental education is being implemented within the colleges of education. Lecturers' understanding of the interdisciplinary nature of environmental education and related concepts was explored. Insights were also gained into problems of implementation which included lecturers' limited understanding of the concept of interdisciplinarity, structural ambiguities, limited training and experience, and a lack of clarity in both local and international literature on environmental education concepts and terms. Specifically the study sought to illuminate the dichotomy between theory and practice, the conflict between the dominant curriculum paradigm and the new emerging paradigm, and tensions between the interdisciplinary nature of environmental education and subject-based disciplines, which lead to problems of implementation. The study could make an important contribution to the current curriculum debate on environmental education in South Africa by illuminating the dichotomy between the theory and the practice of environmental education, and the problems involved in translating interdisciplinary approaches into workable classroom practices within discipline based curriculum structures.
- Full Text:
- Date Issued: 1994
A case study of the group work management techniques of an English second language teacher in the Molopo circuit of Bophuthatswana
- Authors: Alfers, Helen Joy
- Date: 1994
- Subjects: English language -- Study and teaching -- South Africa -- Bophuthatswana--Foreign speakers
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1441 , http://hdl.handle.net/10962/d1003322
- Description: This study examines the small group work management techniques of a teacher of English in a second language classroom in Bophuthatswana. The school at which the observation takes place, is a black secondary school in Mmabatho which follows the Department of Education and Training (DET) syllabus and writes the DET external matriculation examination. The goal of the research is to assess and evaluate the methods the teacher uses in managing group work according to five specified areas. These areas are noted for their importance in the successful management of group work. The report on the findings of this research reveals that the teacher's understanding of the nature of small group work differs from the accepted characteristics of successful group work management as interpreted by authorities in this field. This gives rise to management techniques that are sometimes inappropriate and ill-considered. Although this study observes only one teacher, the findings indicate the need for more classroom-based research in order to establish the true nature of classroom practice. Assumptions about classroom practice are too readily made by innovators, syllabus designers and textbook writers who design materials based on methodologies which can be complex and difficult to implement. These methodologies require understanding and commitment from the teacher. However, the pre-service and in-service education and development that the teacher receives often does not guarantee understanding of the processes involved nor does it generate the necessary commitment to small group work as an effective teaching technique.
- Full Text:
- Date Issued: 1994
- Authors: Alfers, Helen Joy
- Date: 1994
- Subjects: English language -- Study and teaching -- South Africa -- Bophuthatswana--Foreign speakers
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1441 , http://hdl.handle.net/10962/d1003322
- Description: This study examines the small group work management techniques of a teacher of English in a second language classroom in Bophuthatswana. The school at which the observation takes place, is a black secondary school in Mmabatho which follows the Department of Education and Training (DET) syllabus and writes the DET external matriculation examination. The goal of the research is to assess and evaluate the methods the teacher uses in managing group work according to five specified areas. These areas are noted for their importance in the successful management of group work. The report on the findings of this research reveals that the teacher's understanding of the nature of small group work differs from the accepted characteristics of successful group work management as interpreted by authorities in this field. This gives rise to management techniques that are sometimes inappropriate and ill-considered. Although this study observes only one teacher, the findings indicate the need for more classroom-based research in order to establish the true nature of classroom practice. Assumptions about classroom practice are too readily made by innovators, syllabus designers and textbook writers who design materials based on methodologies which can be complex and difficult to implement. These methodologies require understanding and commitment from the teacher. However, the pre-service and in-service education and development that the teacher receives often does not guarantee understanding of the processes involved nor does it generate the necessary commitment to small group work as an effective teaching technique.
- Full Text:
- Date Issued: 1994
Systematics and Osteology of the Zoarcidae (Teleostei: Perciformes)
- Authors: Anderson, M Eric
- Date: 1994
- Language: English
- Type: Text
- Identifier: vital:15033 , http://hdl.handle.net/10962/d1019910 , ISSN 0073-4381 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 60
- Description: The eelpouts, Zoarcidae, are a group of perciform fishes, most species of which inhabit continental shelves and slopes of boreal seas. There are about 220 valid species of eelpouts; most are rare, deep-sea forms and the systematics and biology of the group has been neglected by most workers. This work is a contribution to the improvement of that state. The anatomy of the Zoarcidae was studied in an attempt to reconstruct phylogeny and establish generic limits. From an analysis of a matrix of 76 characters, the 45 genera recognised here form 4 subfamilies. The Lycozoarcinae contains only the primitive Lycozoarces hubbsi. The others, Zoarcinae, Gymnelinae, and Lycodinae, for the most part, include genera recognised in previous classifications (Gill, 1862, 1864; Andriashev, 1939). The more primitive zoarcids are characterised by having 4-6 suborbital bones arranged in a circular pattern close to the orbit, and “complete” cephalic lateralis pore patterns, except some of the few deep-sea forms. The more derived zoarcids are characterized by having 6-11 suborbital bones arranged in an angled, or “L”-shaped" pattern away from the orbit (except a few which have lost some bones) and the loss of the interorbital pores (except for some reversals in Lycenchelys and Lycodapus). Zoarcids are considered to have originated in the North Pacific Ocean, perhaps as early as the Eocene, when a pre-percoid radiation occurred. The suborder Zoarcoidei (today some 8-9 families) spread across the Pacific rim. Among Zoarcidae, a pre-Miocene radiation took place along the western coasts of the Americas, with areas of endemism forming in the Magellan Province of South America and Antarctica. Subsequent spreading back into northern waters occurred in Melanostigma and Pachycara. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1994
- Authors: Anderson, M Eric
- Date: 1994
- Language: English
- Type: Text
- Identifier: vital:15033 , http://hdl.handle.net/10962/d1019910 , ISSN 0073-4381 , Ichthyological Bulletin of the J.L.B. Smith Institute of Ichthyology; No. 60
- Description: The eelpouts, Zoarcidae, are a group of perciform fishes, most species of which inhabit continental shelves and slopes of boreal seas. There are about 220 valid species of eelpouts; most are rare, deep-sea forms and the systematics and biology of the group has been neglected by most workers. This work is a contribution to the improvement of that state. The anatomy of the Zoarcidae was studied in an attempt to reconstruct phylogeny and establish generic limits. From an analysis of a matrix of 76 characters, the 45 genera recognised here form 4 subfamilies. The Lycozoarcinae contains only the primitive Lycozoarces hubbsi. The others, Zoarcinae, Gymnelinae, and Lycodinae, for the most part, include genera recognised in previous classifications (Gill, 1862, 1864; Andriashev, 1939). The more primitive zoarcids are characterised by having 4-6 suborbital bones arranged in a circular pattern close to the orbit, and “complete” cephalic lateralis pore patterns, except some of the few deep-sea forms. The more derived zoarcids are characterized by having 6-11 suborbital bones arranged in an angled, or “L”-shaped" pattern away from the orbit (except a few which have lost some bones) and the loss of the interorbital pores (except for some reversals in Lycenchelys and Lycodapus). Zoarcids are considered to have originated in the North Pacific Ocean, perhaps as early as the Eocene, when a pre-percoid radiation occurred. The suborder Zoarcoidei (today some 8-9 families) spread across the Pacific rim. Among Zoarcidae, a pre-Miocene radiation took place along the western coasts of the Americas, with areas of endemism forming in the Magellan Province of South America and Antarctica. Subsequent spreading back into northern waters occurred in Melanostigma and Pachycara. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1994
The first Bothriolepsis-associated Devonian fish fauna from Africa
- Anderson, M Eric, Hiller, Norton, Gess, Robert W
- Authors: Anderson, M Eric , Hiller, Norton , Gess, Robert W
- Date: 1994
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73852 , vital:30235 , https://journals.co.za/content/sajsci/90/7/AJA00382353_5900
- Description: An advanced diplacanthid (Climatiiformes) is described from a Famennian estuarine environment of South Africa. It is characterized by having exceptionally long thin fin spines and a deep body form. Unusual details of the fins and fin spine insertions are preserved. This is the first record of a diplacanthid from the Southern Hemisphere.
- Full Text:
- Date Issued: 1994
- Authors: Anderson, M Eric , Hiller, Norton , Gess, Robert W
- Date: 1994
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73852 , vital:30235 , https://journals.co.za/content/sajsci/90/7/AJA00382353_5900
- Description: An advanced diplacanthid (Climatiiformes) is described from a Famennian estuarine environment of South Africa. It is characterized by having exceptionally long thin fin spines and a deep body form. Unusual details of the fins and fin spine insertions are preserved. This is the first record of a diplacanthid from the Southern Hemisphere.
- Full Text:
- Date Issued: 1994
The relative discriminatory power of a selection of neuropsychological tests in Alzheimer's disease
- Authors: Aronson, Steven
- Date: 1994
- Subjects: Alzheimer's disease -- Physiological aspects , Neuropsychological tests
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3154 , http://hdl.handle.net/10962/d1007498 , Alzheimer's disease -- Physiological aspects , Neuropsychological tests
- Description: KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1994
- Authors: Aronson, Steven
- Date: 1994
- Subjects: Alzheimer's disease -- Physiological aspects , Neuropsychological tests
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3154 , http://hdl.handle.net/10962/d1007498 , Alzheimer's disease -- Physiological aspects , Neuropsychological tests
- Description: KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1994
Africa's golden age debunked: a study of the sources of select black African historical novels
- Ayivor, Moses Geoffrey Kwame
- Authors: Ayivor, Moses Geoffrey Kwame
- Date: 1994
- Subjects: Mofolo, Thomas, 1875?-1948 -- Criticism and interpretation , Plaatje, Sol. T. (Solomon Tshekisho), 1876-1932 , Armah, Ayi Kwei, 1939 -- Criticism and interpretation , Ouologuem, Yambo, 1940- , African literature -- 20th century -- History and criticism , African literature -- Black authors -- History and criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2232 , http://hdl.handle.net/10962/d1002275 , Mofolo, Thomas, 1875?-1948 -- Criticism and interpretation , Plaatje, Sol. T. (Solomon Tshekisho), 1876-1932 , Armah, Ayi Kwei, 1939 -- Criticism and interpretation , Ouologuem, Yambo, 1940- , African literature -- 20th century -- History and criticism , African literature -- Black authors -- History and criticism
- Description: The main thesis of this dissertation is that even a casual analysis of African writing reveals that contemporary African literature has and is still undergoing a distinctive metamorphosis. This change, which amounts to a significant departure from the early fifties, derives its creative impulse from demonic anger and cynical iconoclasm and is triggered by the mind-shattering disillusion that followed independence. The proclivity towards tyranny and the exploitation of the ruled in modern Africa is traced by radical African creative writers to an ancient source: the legendary and god-like rulers of precolonial Africa. Ouologuem's Bound to Violence and Armah's Two Thousand Seasons and The Healers hypothesize that past sins begot present sins. The legendary warrior heroes of the past, whose glory and splendour were once exalted in African writing, are now ruthlessly disentombed and paraded as miscreants and despots, who not only brutalized and sold their people into slavery but also ideologically fabricated their own legends and myths in order to maximize their tyrannical power. The preoccupation of these works is, therefore, to divest the ancient heroes of their false glory. contemporary critics tend to perceive this anti-traditional posture purely as a modern trend in African literature. The truth of the matter, however, is that the literary foundations of this anti-nativist/anti-Afrocentric literary tradition were laid by Thomas Mofolo and Sol Plaatje, whose Chaka (1925) and Mhudi (1930) are the precursors. The five primary works in this study parody and veer away from the generally accepted traditional African epic heroism and recorded history towards a communal heroic ideal which celebrates the larger community instead of the single epic heroes normally romanticized in African legendary tradition. These novelists, while dismantling the European and African myths about Africa's Golden Age, also disfigure the often glorified ancient historical landmarks and the fabled heroes of Africa's oral and recorded history. The rationale behind this investigation is the fact that though these works have innovated, assimilated, and parodied the African oral arts, particularly traditional African epic heroism, no detailed study has been made to explore the literary transformation these texts have undergone as written works. Treating African texts only as appendages of Western literature may undermine the ability of the critical evaluations which go into the heart of these texts and unravel their deeper meanings. The outcome of this kind of approach is that pertinent issues of style and theme originating from negro-African metaphysics, oral traditions, and iconography could thereby be left unexplored. Besides, the bulk of the current body of criticism on African literature, particularly on colonial Africa, tends to concentrate on colonialist Christian values and Western literary production models. One of the overriding concerns of this research, therefore, is to veer away from merely rehashing Eurocentric pronouncements on European influences and literary modes parodied by these works, by taking a fresh. look at the texts from the perspective of Afrocentrism and in particular from the point of view of the traditional African oral bards. To this end, therefore, the dissertation is divided into six main chapters and a short concluding chapter: Chapter 1, A Survey of Black Representations of Pre-colonial Africa, functions as an introduction, sketches the European image versus the Black counter-discourse, and locates the study within the current debate on the concept of pre-colonial Africa's Golden Age. Chapter 2, Thomas Mofolo's "Inverted Epic Hero", the nucleus of the study I analyzes the anti-epic and ironic modes manipulated by the text and also maps out the epic generic framework which structures the whole dissertation. Chapter 3, Traditional African Epic Heroism Revised, discusses Plaatje's Mhudi, paying special attention to the text's deployment of the African epic genre as well as the caricaturist and the anti-heroic modes. In Chapter 4, Yambo Ouologuem's Bound to Violence is examined under the title A World Trapped in an Orgy of Violence, Barbarism and Servitude. African oral art is used as the hermeneutic key in unlocking the complexities of Ouologuem's novel. Chapter 5, The African Anti-Legendary Creative Mythology, scrutinizes Armah's Two Thousand Seasons, highlighting, among other topics, Armah's daring innovative stylistic experimentation. Chapter 6, entitled The Akan Iconic Forest of Symbols, deals with Armah' s The Healers, concentrating on the Akan iconographic backdrop which shapes and informs this work. And finally, The Metamorphosis of Traditional African Epic Heroism, the title of the concluding chapter, sums up this dissertation.
- Full Text:
- Date Issued: 1994
- Authors: Ayivor, Moses Geoffrey Kwame
- Date: 1994
- Subjects: Mofolo, Thomas, 1875?-1948 -- Criticism and interpretation , Plaatje, Sol. T. (Solomon Tshekisho), 1876-1932 , Armah, Ayi Kwei, 1939 -- Criticism and interpretation , Ouologuem, Yambo, 1940- , African literature -- 20th century -- History and criticism , African literature -- Black authors -- History and criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2232 , http://hdl.handle.net/10962/d1002275 , Mofolo, Thomas, 1875?-1948 -- Criticism and interpretation , Plaatje, Sol. T. (Solomon Tshekisho), 1876-1932 , Armah, Ayi Kwei, 1939 -- Criticism and interpretation , Ouologuem, Yambo, 1940- , African literature -- 20th century -- History and criticism , African literature -- Black authors -- History and criticism
- Description: The main thesis of this dissertation is that even a casual analysis of African writing reveals that contemporary African literature has and is still undergoing a distinctive metamorphosis. This change, which amounts to a significant departure from the early fifties, derives its creative impulse from demonic anger and cynical iconoclasm and is triggered by the mind-shattering disillusion that followed independence. The proclivity towards tyranny and the exploitation of the ruled in modern Africa is traced by radical African creative writers to an ancient source: the legendary and god-like rulers of precolonial Africa. Ouologuem's Bound to Violence and Armah's Two Thousand Seasons and The Healers hypothesize that past sins begot present sins. The legendary warrior heroes of the past, whose glory and splendour were once exalted in African writing, are now ruthlessly disentombed and paraded as miscreants and despots, who not only brutalized and sold their people into slavery but also ideologically fabricated their own legends and myths in order to maximize their tyrannical power. The preoccupation of these works is, therefore, to divest the ancient heroes of their false glory. contemporary critics tend to perceive this anti-traditional posture purely as a modern trend in African literature. The truth of the matter, however, is that the literary foundations of this anti-nativist/anti-Afrocentric literary tradition were laid by Thomas Mofolo and Sol Plaatje, whose Chaka (1925) and Mhudi (1930) are the precursors. The five primary works in this study parody and veer away from the generally accepted traditional African epic heroism and recorded history towards a communal heroic ideal which celebrates the larger community instead of the single epic heroes normally romanticized in African legendary tradition. These novelists, while dismantling the European and African myths about Africa's Golden Age, also disfigure the often glorified ancient historical landmarks and the fabled heroes of Africa's oral and recorded history. The rationale behind this investigation is the fact that though these works have innovated, assimilated, and parodied the African oral arts, particularly traditional African epic heroism, no detailed study has been made to explore the literary transformation these texts have undergone as written works. Treating African texts only as appendages of Western literature may undermine the ability of the critical evaluations which go into the heart of these texts and unravel their deeper meanings. The outcome of this kind of approach is that pertinent issues of style and theme originating from negro-African metaphysics, oral traditions, and iconography could thereby be left unexplored. Besides, the bulk of the current body of criticism on African literature, particularly on colonial Africa, tends to concentrate on colonialist Christian values and Western literary production models. One of the overriding concerns of this research, therefore, is to veer away from merely rehashing Eurocentric pronouncements on European influences and literary modes parodied by these works, by taking a fresh. look at the texts from the perspective of Afrocentrism and in particular from the point of view of the traditional African oral bards. To this end, therefore, the dissertation is divided into six main chapters and a short concluding chapter: Chapter 1, A Survey of Black Representations of Pre-colonial Africa, functions as an introduction, sketches the European image versus the Black counter-discourse, and locates the study within the current debate on the concept of pre-colonial Africa's Golden Age. Chapter 2, Thomas Mofolo's "Inverted Epic Hero", the nucleus of the study I analyzes the anti-epic and ironic modes manipulated by the text and also maps out the epic generic framework which structures the whole dissertation. Chapter 3, Traditional African Epic Heroism Revised, discusses Plaatje's Mhudi, paying special attention to the text's deployment of the African epic genre as well as the caricaturist and the anti-heroic modes. In Chapter 4, Yambo Ouologuem's Bound to Violence is examined under the title A World Trapped in an Orgy of Violence, Barbarism and Servitude. African oral art is used as the hermeneutic key in unlocking the complexities of Ouologuem's novel. Chapter 5, The African Anti-Legendary Creative Mythology, scrutinizes Armah's Two Thousand Seasons, highlighting, among other topics, Armah's daring innovative stylistic experimentation. Chapter 6, entitled The Akan Iconic Forest of Symbols, deals with Armah' s The Healers, concentrating on the Akan iconographic backdrop which shapes and informs this work. And finally, The Metamorphosis of Traditional African Epic Heroism, the title of the concluding chapter, sums up this dissertation.
- Full Text:
- Date Issued: 1994
The contradictions of community politics: the African petty bourgeoisie and the New Brighton Advisory Board, c1937-1952
- Authors: Baines, Gary F
- Date: 1994
- Language: English
- Type: Article
- Identifier: vital:6147 , http://hdl.handle.net/10962/d1003831
- Full Text: false
- Date Issued: 1994
- Authors: Baines, Gary F
- Date: 1994
- Language: English
- Type: Article
- Identifier: vital:6147 , http://hdl.handle.net/10962/d1003831
- Full Text: false
- Date Issued: 1994
Cogitator : a parallel, fuzzy, database-driven expert system
- Authors: Baise, Paul
- Date: 1994 , 2012-10-08
- Subjects: Expert systems (Computer science) , Artificial intelligence -- Computer programs , System design , Cogitator (Computer system)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4667 , http://hdl.handle.net/10962/d1006684 , Expert systems (Computer science) , Artificial intelligence -- Computer programs , System design , Cogitator (Computer system)
- Description: The quest to build anthropomorphic machines has led researchers to focus on knowledge and the manipulation thereof. Recently, the expert system was proposed as a solution, working well in small, well understood domains. However these initial attempts highlighted the tedious process associated with building systems to display intelligence, the most notable being the Knowledge Acquisition Bottleneck. Attempts to circumvent this problem have led researchers to propose the use of machine learning databases as a source of knowledge. Attempts to utilise databases as sources of knowledge has led to the development Database-Driven Expert Systems. Furthermore, it has been ascertained that a requisite for intelligent systems is powerful computation. In response to these problems and proposals, a new type of database-driven expert system, Cogitator is proposed. It is shown to circumvent the Knowledge Acquisition Bottleneck and posess many other advantages over both traditional expert systems and connectionist systems, whilst having non-serious disadvantages. , KMBT_223
- Full Text:
- Date Issued: 1994
- Authors: Baise, Paul
- Date: 1994 , 2012-10-08
- Subjects: Expert systems (Computer science) , Artificial intelligence -- Computer programs , System design , Cogitator (Computer system)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4667 , http://hdl.handle.net/10962/d1006684 , Expert systems (Computer science) , Artificial intelligence -- Computer programs , System design , Cogitator (Computer system)
- Description: The quest to build anthropomorphic machines has led researchers to focus on knowledge and the manipulation thereof. Recently, the expert system was proposed as a solution, working well in small, well understood domains. However these initial attempts highlighted the tedious process associated with building systems to display intelligence, the most notable being the Knowledge Acquisition Bottleneck. Attempts to circumvent this problem have led researchers to propose the use of machine learning databases as a source of knowledge. Attempts to utilise databases as sources of knowledge has led to the development Database-Driven Expert Systems. Furthermore, it has been ascertained that a requisite for intelligent systems is powerful computation. In response to these problems and proposals, a new type of database-driven expert system, Cogitator is proposed. It is shown to circumvent the Knowledge Acquisition Bottleneck and posess many other advantages over both traditional expert systems and connectionist systems, whilst having non-serious disadvantages. , KMBT_223
- Full Text:
- Date Issued: 1994
Parallel implementation of a virtual reality system on a transputer architecture
- Authors: Bangay, Shaun Douglas
- Date: 1994 , 2012-10-11
- Subjects: Virtual reality , Computer simulation , Transputers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4668 , http://hdl.handle.net/10962/d1006687 , Virtual reality , Computer simulation , Transputers
- Description: A Virtual Reality is a computer model of an environment, actual or imagined, presented to a user in as realistic a fashion as possible. Stereo goggles may be used to provide the user with a view of the modelled environment from within the environment, while a data-glove is used to interact with the environment. To simulate reality on a computer, the machine has to produce realistic images rapidly. Such a requirement usually necessitates expensive equipment. This thesis presents an implementation of a virtual reality system on a transputer architecture. The system is general, and is intended to provide support for the development of various virtual environments. The three main components of the system are the output device drivers, the input device drivers, and the virtual world kernel. This last component is responsible for the simulation of the virtual world. The rendering system is described in detail. Various methods for implementing the components of the graphics pipeline are discussed. These are then generalised to make use of the facilities provided by the transputer processor for parallel processing. A number of different decomposition techniques are implemented and compared. The emphasis in this section is on the speed at which the world can be rendered, and the interaction latency involved. In the best case, where almost linear speedup is obtained, a world containing over 250 polygons is rendered at 32 frames/second. The bandwidth of the transputer links is the major factor limiting speedup. A description is given of an input device driver which makes use of a powerglove. Techniques for overcoming the limitations of this device, and for interacting with the virtual world, are discussed. The virtual world kernel is designed to make extensive use of the parallel processing facilities provided by transputers. It is capable of providing support for mUltiple worlds concurrently, and for multiple users interacting with these worlds. Two applications are described that were successfully implemented using this system. The design of the system is compared with other recently developed virtual reality systems. Features that are common or advantageous in each of the systems are discussed. The system described in this thesis compares favourably, particularly in its use of parallel processors. , KMBT_223
- Full Text:
- Date Issued: 1994
- Authors: Bangay, Shaun Douglas
- Date: 1994 , 2012-10-11
- Subjects: Virtual reality , Computer simulation , Transputers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4668 , http://hdl.handle.net/10962/d1006687 , Virtual reality , Computer simulation , Transputers
- Description: A Virtual Reality is a computer model of an environment, actual or imagined, presented to a user in as realistic a fashion as possible. Stereo goggles may be used to provide the user with a view of the modelled environment from within the environment, while a data-glove is used to interact with the environment. To simulate reality on a computer, the machine has to produce realistic images rapidly. Such a requirement usually necessitates expensive equipment. This thesis presents an implementation of a virtual reality system on a transputer architecture. The system is general, and is intended to provide support for the development of various virtual environments. The three main components of the system are the output device drivers, the input device drivers, and the virtual world kernel. This last component is responsible for the simulation of the virtual world. The rendering system is described in detail. Various methods for implementing the components of the graphics pipeline are discussed. These are then generalised to make use of the facilities provided by the transputer processor for parallel processing. A number of different decomposition techniques are implemented and compared. The emphasis in this section is on the speed at which the world can be rendered, and the interaction latency involved. In the best case, where almost linear speedup is obtained, a world containing over 250 polygons is rendered at 32 frames/second. The bandwidth of the transputer links is the major factor limiting speedup. A description is given of an input device driver which makes use of a powerglove. Techniques for overcoming the limitations of this device, and for interacting with the virtual world, are discussed. The virtual world kernel is designed to make extensive use of the parallel processing facilities provided by transputers. It is capable of providing support for mUltiple worlds concurrently, and for multiple users interacting with these worlds. Two applications are described that were successfully implemented using this system. The design of the system is compared with other recently developed virtual reality systems. Features that are common or advantageous in each of the systems are discussed. The system described in this thesis compares favourably, particularly in its use of parallel processors. , KMBT_223
- Full Text:
- Date Issued: 1994
Farmers' strategies and their implications for land reform in the Orange Free State
- Authors: Beinart, William
- Date: 1994
- Subjects: Agriculture -- Orange Free State Land reform -- South Africa -- Orange Free State Land tenure -- Orange Free State
- Language: English
- Type: text , Manuscript
- Identifier: http://hdl.handle.net/10962/2813 , vital:20328
- Description: It is possible to conjure a wide variety of future agricultural scenarios in South Africa. But new policies should be developed only with close attention to what exists and what is feasible. Analysis of the potential for land reform should remain sensitive to local ecological and economic conditions and to the current strategies of both farmers and dispossessed. Rural life for many people remains insecure. Farmworkers are particularly vulnerable at present and might become more so in a phase of rapid reform and uncertainty. Although the most carefully planned strategy of reform might be undermined by the sheer demand for land or informal reoccupations, the aims of restitution, justice and redistribution should be tempered by the equally difficult demands of production. Drawing on material from a local research project in the Orange Free State (OFS), done jointly with Colin Murray, this article concentrates on three issues: patterns of land ownership; farming strategies; and land availability. The position of farmworkers and those who have recently moved off farms, as well as the potential for new patterns of occupation will be addressed in subsequent project papers (Murray, 1993). , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1994
- Authors: Beinart, William
- Date: 1994
- Subjects: Agriculture -- Orange Free State Land reform -- South Africa -- Orange Free State Land tenure -- Orange Free State
- Language: English
- Type: text , Manuscript
- Identifier: http://hdl.handle.net/10962/2813 , vital:20328
- Description: It is possible to conjure a wide variety of future agricultural scenarios in South Africa. But new policies should be developed only with close attention to what exists and what is feasible. Analysis of the potential for land reform should remain sensitive to local ecological and economic conditions and to the current strategies of both farmers and dispossessed. Rural life for many people remains insecure. Farmworkers are particularly vulnerable at present and might become more so in a phase of rapid reform and uncertainty. Although the most carefully planned strategy of reform might be undermined by the sheer demand for land or informal reoccupations, the aims of restitution, justice and redistribution should be tempered by the equally difficult demands of production. Drawing on material from a local research project in the Orange Free State (OFS), done jointly with Colin Murray, this article concentrates on three issues: patterns of land ownership; farming strategies; and land availability. The position of farmworkers and those who have recently moved off farms, as well as the potential for new patterns of occupation will be addressed in subsequent project papers (Murray, 1993). , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1994
A classroom-based investigation into the potential of a computer-mediated criterion-referenced test as an evaluation instrument for the assessment of primary end user spreadsheet skills
- Authors: Benn, Kenneth Robert Andrew
- Date: 1994
- Subjects: Education -- Data processing Electronic spreadsheets Criterion-referenced tests Educational tests and measurements
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1447 , http://hdl.handle.net/10962/d1003328
- Description: The demand for innovative end users of information technology is increasing along with the proliferation of computer equipment within the workplace. This has resulted in increasing demands being made upon educational institutions responsible for the education of computer end users. The demands placed upon the teachers are particularly high. Large class groups and limited physical resources make the task especially difficult. One of the most time consuming, yet important, tasks is that of student evaluation. To effectively assess the practical work of information technology students requires intensive study of the storage media upon which the students'efforts have been saved. The purpose of this study was to assess the suitability of criterion-referenced testing techniques applied to the evaluation of end user computing students. Objective questions were administered to the students using Question Mark, a computer-managed test delivery system which enabled quick and efficient management of scoring and data manipulation for empirical analysis. The study was limited to the classroom situation and the assessment of primary spreadsheet skills. In order to operate within these boundaries, empirical techniques were used which enabled the timeous analysis of the students' test results. The findings of this study proved to be encouraging. Computer-mediated criterion-referenced testing techniques were found to be sufficiently reliable for classroom practice when used to assess primary spreadsheet skills. The validation of the assessment technique proved to be problematic because of the constraints imposed by normal classroom practice as well as the lack of an established methodology for evaluating spreadsheet skills. However, sufficient evidence was obtained to warrant further research aimed at assessing the use of computer-mediated criterion-referenced tests to evaluate information technology end user learning in situations beyond the boundaries of the classroom, such as a national certification examination.
- Full Text:
- Date Issued: 1994
- Authors: Benn, Kenneth Robert Andrew
- Date: 1994
- Subjects: Education -- Data processing Electronic spreadsheets Criterion-referenced tests Educational tests and measurements
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1447 , http://hdl.handle.net/10962/d1003328
- Description: The demand for innovative end users of information technology is increasing along with the proliferation of computer equipment within the workplace. This has resulted in increasing demands being made upon educational institutions responsible for the education of computer end users. The demands placed upon the teachers are particularly high. Large class groups and limited physical resources make the task especially difficult. One of the most time consuming, yet important, tasks is that of student evaluation. To effectively assess the practical work of information technology students requires intensive study of the storage media upon which the students'efforts have been saved. The purpose of this study was to assess the suitability of criterion-referenced testing techniques applied to the evaluation of end user computing students. Objective questions were administered to the students using Question Mark, a computer-managed test delivery system which enabled quick and efficient management of scoring and data manipulation for empirical analysis. The study was limited to the classroom situation and the assessment of primary spreadsheet skills. In order to operate within these boundaries, empirical techniques were used which enabled the timeous analysis of the students' test results. The findings of this study proved to be encouraging. Computer-mediated criterion-referenced testing techniques were found to be sufficiently reliable for classroom practice when used to assess primary spreadsheet skills. The validation of the assessment technique proved to be problematic because of the constraints imposed by normal classroom practice as well as the lack of an established methodology for evaluating spreadsheet skills. However, sufficient evidence was obtained to warrant further research aimed at assessing the use of computer-mediated criterion-referenced tests to evaluate information technology end user learning in situations beyond the boundaries of the classroom, such as a national certification examination.
- Full Text:
- Date Issued: 1994
Delineation of buried stream channels using geophysical techniques
- Authors: Biedler, Murray W
- Date: 1994
- Subjects: Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4823 , http://hdl.handle.net/10962/d1005498 , Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Description: This study sets out to evaluate the use of geophysical methods for delineating buried stream channels, which can act as zones of preferential flow within a less hydraulically conductive aquifer. This information is important for gaining an understanding of flow dynamics of alluvial systems. The most reliable method of delineating the dimensions of aquifers is by drilling, which is an expensive proposition and is best preceded by a preliminary geophysical study to help define target zones for a drilling program. The study area is located adjacent to the Coerney River in the Sundays River Valley. Geologically it consists of approximately 5 metres of alluvial fines, covering 3 metres of coarse cobbles and boulders, all underlain by alternating siltstone and sandstone beds of indeterminate thickness. Throughout the area the water is very shallow at approximately 2 metres depth and the groundwater tends to be very saline. An air photo study revealed an old oxbow channel that had been covered over by subsequent agricultural land use. The geophysical methods available for the study were portable seismic refraction, electrical resistivity and electromagnetics. Preliminary field tests clearly showed that seismics did not produce valid results. The methods of electrical resistivity and electromagnetics produced good data and were subjected to further assessment. A grid was surveyed over the study area and both geophysical methods were applied at regularly spaced stations. Soil samples were taken over the same survey grid and analyzed for electrical conductivity in a soils laboratory. The results were compared to the geophysical data in an attempt to quantify the relationship between geophysical response and soil salinity. The data from the electromagnetic survey showed areas of low electrical conductivity which was a possible indication of zones of preferential groundwater flow. A transect of boreholes was drilled over selected electrical conductivity lows and successfully intersected the buried stream channel. A comparison of the borehole logs with the layered earth models from the Vertical Electrical Soundings indicated that the electrical resistivity method was not responding to the features of the buried stream channel and the cobblestone layer. This proved the electromagnetic method to be more valuable for this particular study
- Full Text:
- Date Issued: 1994
- Authors: Biedler, Murray W
- Date: 1994
- Subjects: Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4823 , http://hdl.handle.net/10962/d1005498 , Stream channelization , Seismic refraction method , Electric prospecting , Electromagnetism , Aquifers -- South Africa , Groundwater , Hydrogeology -- South Africa
- Description: This study sets out to evaluate the use of geophysical methods for delineating buried stream channels, which can act as zones of preferential flow within a less hydraulically conductive aquifer. This information is important for gaining an understanding of flow dynamics of alluvial systems. The most reliable method of delineating the dimensions of aquifers is by drilling, which is an expensive proposition and is best preceded by a preliminary geophysical study to help define target zones for a drilling program. The study area is located adjacent to the Coerney River in the Sundays River Valley. Geologically it consists of approximately 5 metres of alluvial fines, covering 3 metres of coarse cobbles and boulders, all underlain by alternating siltstone and sandstone beds of indeterminate thickness. Throughout the area the water is very shallow at approximately 2 metres depth and the groundwater tends to be very saline. An air photo study revealed an old oxbow channel that had been covered over by subsequent agricultural land use. The geophysical methods available for the study were portable seismic refraction, electrical resistivity and electromagnetics. Preliminary field tests clearly showed that seismics did not produce valid results. The methods of electrical resistivity and electromagnetics produced good data and were subjected to further assessment. A grid was surveyed over the study area and both geophysical methods were applied at regularly spaced stations. Soil samples were taken over the same survey grid and analyzed for electrical conductivity in a soils laboratory. The results were compared to the geophysical data in an attempt to quantify the relationship between geophysical response and soil salinity. The data from the electromagnetic survey showed areas of low electrical conductivity which was a possible indication of zones of preferential groundwater flow. A transect of boreholes was drilled over selected electrical conductivity lows and successfully intersected the buried stream channel. A comparison of the borehole logs with the layered earth models from the Vertical Electrical Soundings indicated that the electrical resistivity method was not responding to the features of the buried stream channel and the cobblestone layer. This proved the electromagnetic method to be more valuable for this particular study
- Full Text:
- Date Issued: 1994
Synthetic and spectroscopic studies of indolizine derivatives
- Authors: Bode, Moira Leanne
- Date: 1994
- Subjects: Indole alkaloids -- Derivatives Spectrum analysis Chemistry, Organic DNA -- Synthesis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4385 , http://hdl.handle.net/10962/d1005050
- Description: The crystalline compound resulting from thermal cyclization of the Baylis-Hillman product, methyl 3-hydroxy-2-methylene-3-(2-pyridyl)propanoate, has been identified as the indolizine derivative, methyl indolizine-2-carboxylate, and this approach involving the reaction of pyridine-2-carboxaldehydes and acrylate analogues has been established as a general route to 2-substituted indolizines. The ease of cyclization the Baylis-Hillman products to indolizines has been shown to increase by converting the hydroxy group to an acetoxy group, and a range of acetylated Baylis-Hillman products were prepared and cyc1ized to the corresponding 2-substituted indolizines, generally in good overall yield. In the reaction of pyridine-2-carboxaldehyde and methyl vinyl ketone, the intermediate cyclized readily and directly to the corresponding indolizine. One- and two-dimensional ¹H and ¹³C NMR analysis of the 2-substituted indolizine products has permitted complete assignment of all ¹H and ¹³C NMR signals, as well as the measurement of all coupling constants for these compounds. A kinetic and mechanistic study has been conducted on the Baylis-Hillman reaction using ¹H NMR spectroscopy. A range of substrates has been examined and the reaction has been found to be third-order overall. A mechanism involving an addition - elimination sequence is proposed, which fits the kinetic data and accounts for observed substituent effects. Reaction of N,N-dimethylacrylamide with pyridine-2-carboxaldehyde in the presence of the tertiary amine catalyst, DABCO, in chloroform, yielded an unexpected product which has been identified by single crystal X-ray diffraction analysis as 1-(2,2,2-trichloro-1-hydroxyethyl)pyridine. Attempted extension of the general indolizine route to the preparation of chromene systems by reacting salicylaldehyde with methyl acrylate in the presence of DABCO, also led to an unexpected, crystalline material, identified by single crystal X-ray diffraction analysis as the coumarin derivative, 3-[(2-formylphenoxy)methyl]coumarin.A series of chloroquine analogues have been prepared from indolizine-2-carboxylic acid, pyrrolo[I,2-a]quinoline-2-carboxylic acid and imidazo[I,2-a]pyridine-2-carboxylic acid by reaction with suitable amines in the presence of the coupling reagent 1, I' -carbonyldiimidazole. This route has been shown to be a vast improvement on earlier procedures and has provided access to both secondary and tertiary indolizine-2-carboxamides. A range of N,N-dialkylindolizine-2-carboxamides have been prepared by this route, and the influence of substituents on their N-CO rotational energy barriers has been determined using variable temperature ¹H and ¹³C NMR techniques. Intercalation with natural DNA by both chloroquine and the synthesized chloroquine analogues has been examined using UV spectrophotometry, and ¹H and ³¹P NMR spectroscopy. The pyrrolo[I,2-a]quinolines have been shown to be DNA intercalators with binding affinities similar to that of the known antimalarial intercalator, chloroquine. In a preliminary study the synthesis of a short oligonucleotide has been undertaken and changes have been observed in the ¹H and ³¹P NMR spectra of the oligonucleotide on addition of the intercalator, chloroquine.
- Full Text:
- Date Issued: 1994
- Authors: Bode, Moira Leanne
- Date: 1994
- Subjects: Indole alkaloids -- Derivatives Spectrum analysis Chemistry, Organic DNA -- Synthesis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4385 , http://hdl.handle.net/10962/d1005050
- Description: The crystalline compound resulting from thermal cyclization of the Baylis-Hillman product, methyl 3-hydroxy-2-methylene-3-(2-pyridyl)propanoate, has been identified as the indolizine derivative, methyl indolizine-2-carboxylate, and this approach involving the reaction of pyridine-2-carboxaldehydes and acrylate analogues has been established as a general route to 2-substituted indolizines. The ease of cyclization the Baylis-Hillman products to indolizines has been shown to increase by converting the hydroxy group to an acetoxy group, and a range of acetylated Baylis-Hillman products were prepared and cyc1ized to the corresponding 2-substituted indolizines, generally in good overall yield. In the reaction of pyridine-2-carboxaldehyde and methyl vinyl ketone, the intermediate cyclized readily and directly to the corresponding indolizine. One- and two-dimensional ¹H and ¹³C NMR analysis of the 2-substituted indolizine products has permitted complete assignment of all ¹H and ¹³C NMR signals, as well as the measurement of all coupling constants for these compounds. A kinetic and mechanistic study has been conducted on the Baylis-Hillman reaction using ¹H NMR spectroscopy. A range of substrates has been examined and the reaction has been found to be third-order overall. A mechanism involving an addition - elimination sequence is proposed, which fits the kinetic data and accounts for observed substituent effects. Reaction of N,N-dimethylacrylamide with pyridine-2-carboxaldehyde in the presence of the tertiary amine catalyst, DABCO, in chloroform, yielded an unexpected product which has been identified by single crystal X-ray diffraction analysis as 1-(2,2,2-trichloro-1-hydroxyethyl)pyridine. Attempted extension of the general indolizine route to the preparation of chromene systems by reacting salicylaldehyde with methyl acrylate in the presence of DABCO, also led to an unexpected, crystalline material, identified by single crystal X-ray diffraction analysis as the coumarin derivative, 3-[(2-formylphenoxy)methyl]coumarin.A series of chloroquine analogues have been prepared from indolizine-2-carboxylic acid, pyrrolo[I,2-a]quinoline-2-carboxylic acid and imidazo[I,2-a]pyridine-2-carboxylic acid by reaction with suitable amines in the presence of the coupling reagent 1, I' -carbonyldiimidazole. This route has been shown to be a vast improvement on earlier procedures and has provided access to both secondary and tertiary indolizine-2-carboxamides. A range of N,N-dialkylindolizine-2-carboxamides have been prepared by this route, and the influence of substituents on their N-CO rotational energy barriers has been determined using variable temperature ¹H and ¹³C NMR techniques. Intercalation with natural DNA by both chloroquine and the synthesized chloroquine analogues has been examined using UV spectrophotometry, and ¹H and ³¹P NMR spectroscopy. The pyrrolo[I,2-a]quinolines have been shown to be DNA intercalators with binding affinities similar to that of the known antimalarial intercalator, chloroquine. In a preliminary study the synthesis of a short oligonucleotide has been undertaken and changes have been observed in the ¹H and ³¹P NMR spectra of the oligonucleotide on addition of the intercalator, chloroquine.
- Full Text:
- Date Issued: 1994
Biocatalytic and biomimetic studies of polyphenol oxidase
- Authors: Burton, Stephanie Gail
- Date: 1994
- Subjects: Phenol oxidase Polyphenols Oxidases
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4028 , http://hdl.handle.net/10962/d1004088
- Description: Mushroom polyphenol oxidase (EC 1.14.18.1) was investigated to determine its potential for application as a biocatalyst in the synthesis of o-quinones, in organic medium. In order to determine the kinetic properties of the biocatalyst, a system was devised which comprised an immobilised polyphenol oxidase extract, functioning in chloroform. The system was hydrated by the addition of buffer. A simple method for the consistent measurement of reaction rates in this heterogenous system was designed and used to obtain detailed enzyme kinetic data relating to optimisation of reaction conditions and substrate specificity. The aqueous content of the system was optimised using p-cresol as a substrate. A crude, immobilised extract of Agaricus bisporus was used to hydroxylate and oxidise a range of selected p-substituted phenolic substrates, yielding, as the sale products, o-quinones. These products were efficiently reduced to catechols by extracting the reaction mixtures with aqueous ascorbic acid solution. The biocatalytic system was also successfully utilised to produce L-DOPA, the drug used to treat Parkinson's disease, from L-acetyl tyrosine ethyl ester (ATEE). Michaelis-Menten kinetics were used to obtain apparent Km and V values with respect to the selected phenolic substrates, and the kinetic parameters obtained were found to correlate well with the steric requirements of the substrates and with their hydrophobicity. In the course of the investigation, a novel ¹H NMR method was used to facilitate measurement of the UV molar absorption coefficients of the o-quinones in reaction mixtures, thus avoiding the necessity to isolate these unstable, water-sensitive products. The biocatalytic system was extended to a continuous process, in which the immobilised enzyme was shown to function successfully in the chloroform medium for several hours, with high conversion rates. Modifications, involving partial purification and the addition of a surfactant, were investigated to determine their effect on the kinetic parameters. The results obtained using partially purified enzyme indicated that the removal of extraneous protein and/or melanoid material lead to a reduced capacity for conversion of sterically demanding substrates. The addition of the anionic detergent, sodium dodecyl sulphate (SOS), enhanced the ability of the biocatalyst to bind and oxidise sterically demanding substrates. These effects are attributed to changes in the polar state of groups within the protein binding pocket, which result in altered flexibility and hydrophobicity. Computer modelling of several biomimetic dinuclear copper complexes also indicated the importance of flexibility for effective biocatalysis. Novel binuclear copper (II complexes, containing a flexible biphenyl spacer and imidazole or benzimidazole donors, were prepared and analysed using NMR, UV, AA and cyclic voltammetric techniques. The complexes were also shown, in a detailed kinetic study, to mimic the catecholase activity of polyphenol oxidase by oxidising 3,5-di-tertbutylcatechol, and to catalyse the coupling of the phenolic substrate 2,4-di-tert-butylphenol. However, the complexes were apparently too flexible to react with smaller substrates. These biomimetic complexes provided valuable insights into the nature of the dinuclear copper binding site.
- Full Text:
- Date Issued: 1994
- Authors: Burton, Stephanie Gail
- Date: 1994
- Subjects: Phenol oxidase Polyphenols Oxidases
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4028 , http://hdl.handle.net/10962/d1004088
- Description: Mushroom polyphenol oxidase (EC 1.14.18.1) was investigated to determine its potential for application as a biocatalyst in the synthesis of o-quinones, in organic medium. In order to determine the kinetic properties of the biocatalyst, a system was devised which comprised an immobilised polyphenol oxidase extract, functioning in chloroform. The system was hydrated by the addition of buffer. A simple method for the consistent measurement of reaction rates in this heterogenous system was designed and used to obtain detailed enzyme kinetic data relating to optimisation of reaction conditions and substrate specificity. The aqueous content of the system was optimised using p-cresol as a substrate. A crude, immobilised extract of Agaricus bisporus was used to hydroxylate and oxidise a range of selected p-substituted phenolic substrates, yielding, as the sale products, o-quinones. These products were efficiently reduced to catechols by extracting the reaction mixtures with aqueous ascorbic acid solution. The biocatalytic system was also successfully utilised to produce L-DOPA, the drug used to treat Parkinson's disease, from L-acetyl tyrosine ethyl ester (ATEE). Michaelis-Menten kinetics were used to obtain apparent Km and V values with respect to the selected phenolic substrates, and the kinetic parameters obtained were found to correlate well with the steric requirements of the substrates and with their hydrophobicity. In the course of the investigation, a novel ¹H NMR method was used to facilitate measurement of the UV molar absorption coefficients of the o-quinones in reaction mixtures, thus avoiding the necessity to isolate these unstable, water-sensitive products. The biocatalytic system was extended to a continuous process, in which the immobilised enzyme was shown to function successfully in the chloroform medium for several hours, with high conversion rates. Modifications, involving partial purification and the addition of a surfactant, were investigated to determine their effect on the kinetic parameters. The results obtained using partially purified enzyme indicated that the removal of extraneous protein and/or melanoid material lead to a reduced capacity for conversion of sterically demanding substrates. The addition of the anionic detergent, sodium dodecyl sulphate (SOS), enhanced the ability of the biocatalyst to bind and oxidise sterically demanding substrates. These effects are attributed to changes in the polar state of groups within the protein binding pocket, which result in altered flexibility and hydrophobicity. Computer modelling of several biomimetic dinuclear copper complexes also indicated the importance of flexibility for effective biocatalysis. Novel binuclear copper (II complexes, containing a flexible biphenyl spacer and imidazole or benzimidazole donors, were prepared and analysed using NMR, UV, AA and cyclic voltammetric techniques. The complexes were also shown, in a detailed kinetic study, to mimic the catecholase activity of polyphenol oxidase by oxidising 3,5-di-tertbutylcatechol, and to catalyse the coupling of the phenolic substrate 2,4-di-tert-butylphenol. However, the complexes were apparently too flexible to react with smaller substrates. These biomimetic complexes provided valuable insights into the nature of the dinuclear copper binding site.
- Full Text:
- Date Issued: 1994
'People's English' in South Africa : theory and practice
- Authors: Butler, Ian
- Date: 1994
- Subjects: English language -- Study and teaching -- South Africa Second language acquisition -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1691 , http://hdl.handle.net/10962/d1003574
- Description: Communicative Language Teaching, an approach to language teaching currently widely prescribed, has been criticised for its unquestioning acceptance of the cultural and political norms of the target language. People's English (an aspect of the larger People's Education movement), on the other hand, offers a philosophy and methodology that takes an actively critical view of language and its relationship to power. In the context of South African society, this stance has had clear political implications. Although still imprecisely defined , the concepts of People's Education and People's English have been debated and discussed by various ant-apartheid movements in recent years. Attempts have also been made to translate the evolving theory into practice through the development of materials and methodologies. This has been achieved on a relatively small scale, with varying degrees of success. Recent reform measures by the South African government have, however, prompted the proponents of People's Education to reassess their position. This thesis presents a historical overview and critical assessment of the development of People's English in South Africa.
- Full Text:
- Date Issued: 1994
- Authors: Butler, Ian
- Date: 1994
- Subjects: English language -- Study and teaching -- South Africa Second language acquisition -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1691 , http://hdl.handle.net/10962/d1003574
- Description: Communicative Language Teaching, an approach to language teaching currently widely prescribed, has been criticised for its unquestioning acceptance of the cultural and political norms of the target language. People's English (an aspect of the larger People's Education movement), on the other hand, offers a philosophy and methodology that takes an actively critical view of language and its relationship to power. In the context of South African society, this stance has had clear political implications. Although still imprecisely defined , the concepts of People's Education and People's English have been debated and discussed by various ant-apartheid movements in recent years. Attempts have also been made to translate the evolving theory into practice through the development of materials and methodologies. This has been achieved on a relatively small scale, with varying degrees of success. Recent reform measures by the South African government have, however, prompted the proponents of People's Education to reassess their position. This thesis presents a historical overview and critical assessment of the development of People's English in South Africa.
- Full Text:
- Date Issued: 1994
Studies on the bioactivities of selected Eastern Cape seaweeds
- Authors: Carter, Anne Margaret
- Date: 1994
- Subjects: Marine algae -- South Africa -- Eastern Cape , Marine algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4033 , http://hdl.handle.net/10962/d1004093 , Marine algae -- South Africa -- Eastern Cape , Marine algae
- Description: In studies on the bioactivities of selected eastern Cape seaweeds, a suitable extraction solvent, namely methanol was used. The antimicrobial, antineoplastic and antiviral activities were investigated, and a seasonal comparison of antimicrobial activities as well as a scanning electron microscopic study were included. A number of algae were found to display significantly high antibacterial activities, of these, the two red algae Plocamium corallorhiza and Laurencia glomerata and the two brown algae Zonaria subarticulata and Ecklonia biruncinata showed the most potent broad spectrum antibacterial activity. L.glomerata and E.biruncinata were active against all five test bacteria, but were inactive against the yeast Candida albicans. C.albicans was the most resistant organism tested,~with only Peyssonelia capensis, f-corallorhiza and Ulva rigida inhibiting its growth. Of the 17 seaweeds tested, none showed any clear seasonal changes in antimicrobial activity. The microorganisms however did vary in their susceptibility to treatment. Staphylococcus aureus and the Micrococcus species were the most susceptible to treatment by the algal extracts, with the Gram positive endospore former, Bacillus subtilis and the two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa showing more resistance to treatment. C.albicans however was the most resistant organism. In the antineoplastic studies, the brown algae Z.subarticulata, E.biruncinata and Sargassum heterophyllum showed potent activity against both the normal, LLCMK, and cancerous, mouse melanoma-3S0 cells, reducing cell growth in each case. The green algae showed potent activity against the cancerous cells, lowering growth to 30% that of the normal cells. Normal cell growth was unaffected or was stimulated by the presence of these algal extracts. The red algae showed no antineoplastic activity. Representatives of each of the red, brown and green algae were used in the brine shrimp (Artemia salina) cytotoxicity study. None of the algae showed any toxicity towards the brine shrimp. In the antiviral studies against Polio Type 1, strain L-Sa, a reduction in virus infectivity was used as an indication of the presence of antiviral properties in the seaweeds tested. This was done by comparing the virus titres of algal-treated cells with those of untreated cells. Six of the algae tested displayed antiviral activity, these were the two Rhodophyceae Hypnea spicifera and L.glomerata, the two Phaeophyceae Dictyopteris macrocarpa and Dictyota naevosa, and the two Chlorophyceae U.rigida and Halimeda cuneata. Of these, D.naevosa showed particularly strong activity, recording a log reduction in virus titre of 4.
- Full Text:
- Date Issued: 1994
- Authors: Carter, Anne Margaret
- Date: 1994
- Subjects: Marine algae -- South Africa -- Eastern Cape , Marine algae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4033 , http://hdl.handle.net/10962/d1004093 , Marine algae -- South Africa -- Eastern Cape , Marine algae
- Description: In studies on the bioactivities of selected eastern Cape seaweeds, a suitable extraction solvent, namely methanol was used. The antimicrobial, antineoplastic and antiviral activities were investigated, and a seasonal comparison of antimicrobial activities as well as a scanning electron microscopic study were included. A number of algae were found to display significantly high antibacterial activities, of these, the two red algae Plocamium corallorhiza and Laurencia glomerata and the two brown algae Zonaria subarticulata and Ecklonia biruncinata showed the most potent broad spectrum antibacterial activity. L.glomerata and E.biruncinata were active against all five test bacteria, but were inactive against the yeast Candida albicans. C.albicans was the most resistant organism tested,~with only Peyssonelia capensis, f-corallorhiza and Ulva rigida inhibiting its growth. Of the 17 seaweeds tested, none showed any clear seasonal changes in antimicrobial activity. The microorganisms however did vary in their susceptibility to treatment. Staphylococcus aureus and the Micrococcus species were the most susceptible to treatment by the algal extracts, with the Gram positive endospore former, Bacillus subtilis and the two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa showing more resistance to treatment. C.albicans however was the most resistant organism. In the antineoplastic studies, the brown algae Z.subarticulata, E.biruncinata and Sargassum heterophyllum showed potent activity against both the normal, LLCMK, and cancerous, mouse melanoma-3S0 cells, reducing cell growth in each case. The green algae showed potent activity against the cancerous cells, lowering growth to 30% that of the normal cells. Normal cell growth was unaffected or was stimulated by the presence of these algal extracts. The red algae showed no antineoplastic activity. Representatives of each of the red, brown and green algae were used in the brine shrimp (Artemia salina) cytotoxicity study. None of the algae showed any toxicity towards the brine shrimp. In the antiviral studies against Polio Type 1, strain L-Sa, a reduction in virus infectivity was used as an indication of the presence of antiviral properties in the seaweeds tested. This was done by comparing the virus titres of algal-treated cells with those of untreated cells. Six of the algae tested displayed antiviral activity, these were the two Rhodophyceae Hypnea spicifera and L.glomerata, the two Phaeophyceae Dictyopteris macrocarpa and Dictyota naevosa, and the two Chlorophyceae U.rigida and Halimeda cuneata. Of these, D.naevosa showed particularly strong activity, recording a log reduction in virus titre of 4.
- Full Text:
- Date Issued: 1994
Centralised bargaining - Where to CWIU
- Chemical Workers Industrial Union (CWIU)
- Authors: Chemical Workers Industrial Union (CWIU)
- Date: 1994
- Subjects: CWIU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/170148 , vital:41862
- Description: Since the late 1980's, there has been a serious realisation on the part of Cosatu and CWIU leadership, of the need for Centralised Bargaining. Two broad areas of concern which pressurised us in this direction were: 1) The low level of class consciousness on the part of the majority of members during this period especially with regard to the complete lack of solidarity around wage struggles. 2) The organisational incapacity of the unions to cope with the excessive demands of plant based bargaining. This wasted resources and undermined the quality of work and achievement of annual wage bargaining. Faced by this reality, achieving consensus on the need for a campaign to achieve centralised bargaining at leadership level was relatively easy. Unions in other sectors eg. metal, mining, clothing, textile and the public sector, regularly set examples of what could be achieved by well run centralised bargaining. Numsa's experience illustrated the strengths and pitfalls of centralised bargaining - ie. Numsa's mandating and report back processes, the Mercedes Benz strike by opponents to the "one bite at the cherry".
- Full Text:
- Date Issued: 1994
- Authors: Chemical Workers Industrial Union (CWIU)
- Date: 1994
- Subjects: CWIU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/170148 , vital:41862
- Description: Since the late 1980's, there has been a serious realisation on the part of Cosatu and CWIU leadership, of the need for Centralised Bargaining. Two broad areas of concern which pressurised us in this direction were: 1) The low level of class consciousness on the part of the majority of members during this period especially with regard to the complete lack of solidarity around wage struggles. 2) The organisational incapacity of the unions to cope with the excessive demands of plant based bargaining. This wasted resources and undermined the quality of work and achievement of annual wage bargaining. Faced by this reality, achieving consensus on the need for a campaign to achieve centralised bargaining at leadership level was relatively easy. Unions in other sectors eg. metal, mining, clothing, textile and the public sector, regularly set examples of what could be achieved by well run centralised bargaining. Numsa's experience illustrated the strengths and pitfalls of centralised bargaining - ie. Numsa's mandating and report back processes, the Mercedes Benz strike by opponents to the "one bite at the cherry".
- Full Text:
- Date Issued: 1994