SADTU Western Cape Bulletin - Vol 1
- SADTU
- Authors: SADTU
- Date: 1993
- Subjects: SADTU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/134655 , vital:37187
- Description: We are forced to acknowledge the major strides which SADTU has made as a union representing the interests of its members. But with equal sobriety and honesty, we have to take stock of the enormous challenges which lie ahead of a union, which is still relatively weak, both structurally and programmatically. Several branches have not been functioning effectively because of the inconsistency of leadership and grassroots members. The crisis of commitment is also reflected in the irregularity of union meetings at site and branch level and the crisis-related activities of SADTU. Because of our weakness in local structures, we are thus forced to respond in a knee-jerk manner to each specific crisis, without consolidating, the members(or non-members) in a union building process.
- Full Text:
- Date Issued: 1993
- Authors: SADTU
- Date: 1993
- Subjects: SADTU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/134655 , vital:37187
- Description: We are forced to acknowledge the major strides which SADTU has made as a union representing the interests of its members. But with equal sobriety and honesty, we have to take stock of the enormous challenges which lie ahead of a union, which is still relatively weak, both structurally and programmatically. Several branches have not been functioning effectively because of the inconsistency of leadership and grassroots members. The crisis of commitment is also reflected in the irregularity of union meetings at site and branch level and the crisis-related activities of SADTU. Because of our weakness in local structures, we are thus forced to respond in a knee-jerk manner to each specific crisis, without consolidating, the members(or non-members) in a union building process.
- Full Text:
- Date Issued: 1993
Sarcasm, conflict and style in Mtywaku's plays
- Authors: Bokwe, Goliath Dumezweni
- Date: 1993
- Subjects: Xhosa drama -- History and criticism , Xhosa language -- Terms and phrases , Drama -- Black authors -- History and criticism , Playwriting
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3594 , http://hdl.handle.net/10962/d1002169 , Xhosa drama -- History and criticism , Xhosa language -- Terms and phrases , Drama -- Black authors -- History and criticism , Playwriting
- Description: The following main aspects of Mtywaku's plays have been dealt with in the dissertation: (i) Sarcasm (ii) Conflict (iii) Style.
- Full Text:
- Date Issued: 1993
- Authors: Bokwe, Goliath Dumezweni
- Date: 1993
- Subjects: Xhosa drama -- History and criticism , Xhosa language -- Terms and phrases , Drama -- Black authors -- History and criticism , Playwriting
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3594 , http://hdl.handle.net/10962/d1002169 , Xhosa drama -- History and criticism , Xhosa language -- Terms and phrases , Drama -- Black authors -- History and criticism , Playwriting
- Description: The following main aspects of Mtywaku's plays have been dealt with in the dissertation: (i) Sarcasm (ii) Conflict (iii) Style.
- Full Text:
- Date Issued: 1993
SASBO and Dishonesty
- SASBO
- Authors: SASBO
- Date: 1993
- Subjects: SASBO
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/160614 , vital:40480
- Description: In the early 1990’s when internal fraud, theft and dishonesty became an issue of major concern, SASBO members decided to state their position on all forms of employee dishonesty. They expressed the view that criminals should be rooted out of the finance sector, because, inter alia: People of low integrity have no place in finance. Criminals also defraud their colleagues. Reduced profits through fraud would mean lower pay increases. Criminals pollute the working environment and their actions cast suspicion on everyone around them. When crimes take place, innocent employees are accused of not exercising sufficient vigilance and are subject to disciplinary actions, including dismissal. The SASBO National Council, therefore, instructed their Union not to protect guilty personnel. Yet they believed that accused members should receive a fair hearing. As a Union representing the interests of employees in a highly vulnerable workplace such as that found in the finance sector, SASBO, then, had a duty to condemn staff defalcation and fraud in the strongest terms, and to play whatever role that was necessary in ensuring that offenders were removed from the system. The need for SASBO to have a documented policy on the handling of cases involving theft, fraud and dishonesty, when its members were accused of being involved, was obvious. Applying the above principles, and aided by its legal advisors, SASBO’s National Council, in September 1993, adopted the following policy on dishonesty:
- Full Text:
- Date Issued: 1993
- Authors: SASBO
- Date: 1993
- Subjects: SASBO
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/160614 , vital:40480
- Description: In the early 1990’s when internal fraud, theft and dishonesty became an issue of major concern, SASBO members decided to state their position on all forms of employee dishonesty. They expressed the view that criminals should be rooted out of the finance sector, because, inter alia: People of low integrity have no place in finance. Criminals also defraud their colleagues. Reduced profits through fraud would mean lower pay increases. Criminals pollute the working environment and their actions cast suspicion on everyone around them. When crimes take place, innocent employees are accused of not exercising sufficient vigilance and are subject to disciplinary actions, including dismissal. The SASBO National Council, therefore, instructed their Union not to protect guilty personnel. Yet they believed that accused members should receive a fair hearing. As a Union representing the interests of employees in a highly vulnerable workplace such as that found in the finance sector, SASBO, then, had a duty to condemn staff defalcation and fraud in the strongest terms, and to play whatever role that was necessary in ensuring that offenders were removed from the system. The need for SASBO to have a documented policy on the handling of cases involving theft, fraud and dishonesty, when its members were accused of being involved, was obvious. Applying the above principles, and aided by its legal advisors, SASBO’s National Council, in September 1993, adopted the following policy on dishonesty:
- Full Text:
- Date Issued: 1993
School guidance and counselling in Natal : present realities and future possibilities
- Authors: Naicker, Dhanasagaran
- Date: 1993
- Subjects: Educational counseling -- South Africa Counseling -- Vocational guidance -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1758 , http://hdl.handle.net/10962/d1003643
- Description: School guidance and counselling is a programme that is complementary to the education process and is seen as a support service for the pupil. However, owing to the apartheid policies of the South African government, all pupils did not have equal access to guidance services. In a post-apartheid South Africa it is anticipated that a unitary education system would emerge to provide equal access to education for all South African pupils and this implies that previous imbalances that existed would have to be addressed. In this study the present state of guidance and counselling services in Natal was investigated and policy options to redress past inequities and to make school guidance and counselling services a reality for all South African pupils, within the context of limited resources were explored.
- Full Text:
- Date Issued: 1993
- Authors: Naicker, Dhanasagaran
- Date: 1993
- Subjects: Educational counseling -- South Africa Counseling -- Vocational guidance -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1758 , http://hdl.handle.net/10962/d1003643
- Description: School guidance and counselling is a programme that is complementary to the education process and is seen as a support service for the pupil. However, owing to the apartheid policies of the South African government, all pupils did not have equal access to guidance services. In a post-apartheid South Africa it is anticipated that a unitary education system would emerge to provide equal access to education for all South African pupils and this implies that previous imbalances that existed would have to be addressed. In this study the present state of guidance and counselling services in Natal was investigated and policy options to redress past inequities and to make school guidance and counselling services a reality for all South African pupils, within the context of limited resources were explored.
- Full Text:
- Date Issued: 1993
Seasonal changes in pituitary and plasma prolactin concentrations, and the role of Prolactin in the control of delayed implantation in female Miniopterus schreibersii
- Authors: Bojarski, Christina
- Date: 1993
- Subjects: Bats -- Reproduction Prolactin -- Research Pituitary hormones Zoology, Experimental
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5764 , http://hdl.handle.net/10962/d1005452
- Description: Mammotropes were successfully identified in the anterior pituitary gland of Miniopterus schreibersii using immunocytochemical (ICC) staining at the light and electron microscopy level. Mammotropes were distributed throughout the gland, were polygonal in shape and during secretory activity contained numerous large secretory granules (350 - 800nm). Using double ICC labelling, prolactin and growth hormone were never co-localiszed and found in individual cells only. Plasma prolactin levels were successfully measured on a monthly basis using radioimmunoassay and monthly pituitary prolactin levels were quantified using morphometric analysis of immunogold ICC staining and densitometry with polyacrylamide gels. Seasonal changes in the ultrastructure of mammotropes, and pituitary and plasma prolactin concentrations in female Miniopterus schreibersii indicated that there was an increase in prolactin secretion during the second half of the period of delayed implantation and that prolactin secretion remained elevated during normal embryonic development and lactation. This suggests that prolactin may be part of the luteotropic and lactogenic complex, and that the hormone might be responsible for terminating the period of delayed implantation. The latter is supported by experiments, where exogenous prolactin initiated precocious implantation during early delayed implantation, and treatment with bromocryptine (which inhibits prolactin synthesis) retarded implantation. Activation of mammotropes to synthesise prolactin and an increase of plasma prolactin levels occurred shortly after the winter solstice (21 June), suggesting that increasing daylength may be the environmental cue, which terminates the period of delayed implantation in Miniopterus schreibersii.
- Full Text:
- Date Issued: 1993
- Authors: Bojarski, Christina
- Date: 1993
- Subjects: Bats -- Reproduction Prolactin -- Research Pituitary hormones Zoology, Experimental
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5764 , http://hdl.handle.net/10962/d1005452
- Description: Mammotropes were successfully identified in the anterior pituitary gland of Miniopterus schreibersii using immunocytochemical (ICC) staining at the light and electron microscopy level. Mammotropes were distributed throughout the gland, were polygonal in shape and during secretory activity contained numerous large secretory granules (350 - 800nm). Using double ICC labelling, prolactin and growth hormone were never co-localiszed and found in individual cells only. Plasma prolactin levels were successfully measured on a monthly basis using radioimmunoassay and monthly pituitary prolactin levels were quantified using morphometric analysis of immunogold ICC staining and densitometry with polyacrylamide gels. Seasonal changes in the ultrastructure of mammotropes, and pituitary and plasma prolactin concentrations in female Miniopterus schreibersii indicated that there was an increase in prolactin secretion during the second half of the period of delayed implantation and that prolactin secretion remained elevated during normal embryonic development and lactation. This suggests that prolactin may be part of the luteotropic and lactogenic complex, and that the hormone might be responsible for terminating the period of delayed implantation. The latter is supported by experiments, where exogenous prolactin initiated precocious implantation during early delayed implantation, and treatment with bromocryptine (which inhibits prolactin synthesis) retarded implantation. Activation of mammotropes to synthesise prolactin and an increase of plasma prolactin levels occurred shortly after the winter solstice (21 June), suggesting that increasing daylength may be the environmental cue, which terminates the period of delayed implantation in Miniopterus schreibersii.
- Full Text:
- Date Issued: 1993
Self-reports on the effectiveness of psychotherapy with therapists-in-training: an 18-month follow-up study at a psychology training clinic
- Authors: Angus, Catherine Clare
- Date: 1993
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193069 , vital:45295
- Description: The purpose of this study is to ascertain whether the clients who make use of the services of the Psychology Clinic at Rhodes University perceive the masters students being trained at the Clinic as providing adequate psychotherapy. Using a sample of 18 clients, who underwent psychotherapy at the Rhodes Psychology Clinic during 1990, a follow-up study was conducted to ascertain the perceived success of that psychotherapy. Those variables most pertinent to the outcome of psychotherapy are examined. The study uses both qualitative and quantitative methodology and shows that, overall, 89% of the clients who participated in this study perceived the psychotherapy at the Rhodes Psychology Clinic to be satisfactory. The study also highlights those factors which were perceived to be negative in the psychotherapeutic equation and it is hoped that the findings can be beneficial in planning more efficient services for the Clinic in the future. , Thesis (MA) -- Faculty of Humanities, Psychology, 1993
- Full Text:
- Date Issued: 1993
- Authors: Angus, Catherine Clare
- Date: 1993
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193069 , vital:45295
- Description: The purpose of this study is to ascertain whether the clients who make use of the services of the Psychology Clinic at Rhodes University perceive the masters students being trained at the Clinic as providing adequate psychotherapy. Using a sample of 18 clients, who underwent psychotherapy at the Rhodes Psychology Clinic during 1990, a follow-up study was conducted to ascertain the perceived success of that psychotherapy. Those variables most pertinent to the outcome of psychotherapy are examined. The study uses both qualitative and quantitative methodology and shows that, overall, 89% of the clients who participated in this study perceived the psychotherapy at the Rhodes Psychology Clinic to be satisfactory. The study also highlights those factors which were perceived to be negative in the psychotherapeutic equation and it is hoped that the findings can be beneficial in planning more efficient services for the Clinic in the future. , Thesis (MA) -- Faculty of Humanities, Psychology, 1993
- Full Text:
- Date Issued: 1993
South African art institutions : their formation and strategy with particular reference to the question of legitimacy
- Authors: Becker, Carl
- Date: 1993
- Subjects: Art schools -- South Africa Art -- Study and teaching -- South Africa Art and society -- South Africa
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2456 , http://hdl.handle.net/10962/d1007622
- Description: I have examined the relationship between the art institution and its social base, and the way in which legitimacy is sought and maintained under changing social circumstances. The social pattern of 'avante garde artist' vs. 'philistine public' has tended to be the context within which 20th century art has developed. The consequent disjuncture between the public art institution and its social base was subsequently accepted as the natural condition of Fine Art production. During the 1980's, two significant factors were to influence this 'natural' condition: i) The demise of 'modernism' internationally, ' which broadened the scope of allowable objects for consideration as Fine Art. ii) Political mobilisation in South Africa was accompanied by calls for democratisation and charges of 'elitism' being levelled against many public institutions. These factors have combined to make the S.A. art institutions (public galleries, tertiary teaching institutions and national art competitions) re-assess their legitimacy, particularly in terms of 'accountability' and 'representativeness' . A close examination of these two factors is essential if one is to gain insight into the current condition of the public art institutions. This research is an attempt to understand the history and the current nature of the shifting relationship between the art institutions and the 'public' in South Africa. A further goal is to assess the extent to which concepts that are valid within the realm of the polity can be transposed into the cultural realm: A tendency prevalent within the cultural debate in South Africa during the 1980's. The emphasis of this mini thesis is on the artworld's perception of its social role. I therefore look at the way changing attitudes are reflected in the statements and writing of leading figures within this sector. The method is to critically analyse texts that pertain to my chosen area of research.
- Full Text:
- Date Issued: 1993
- Authors: Becker, Carl
- Date: 1993
- Subjects: Art schools -- South Africa Art -- Study and teaching -- South Africa Art and society -- South Africa
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2456 , http://hdl.handle.net/10962/d1007622
- Description: I have examined the relationship between the art institution and its social base, and the way in which legitimacy is sought and maintained under changing social circumstances. The social pattern of 'avante garde artist' vs. 'philistine public' has tended to be the context within which 20th century art has developed. The consequent disjuncture between the public art institution and its social base was subsequently accepted as the natural condition of Fine Art production. During the 1980's, two significant factors were to influence this 'natural' condition: i) The demise of 'modernism' internationally, ' which broadened the scope of allowable objects for consideration as Fine Art. ii) Political mobilisation in South Africa was accompanied by calls for democratisation and charges of 'elitism' being levelled against many public institutions. These factors have combined to make the S.A. art institutions (public galleries, tertiary teaching institutions and national art competitions) re-assess their legitimacy, particularly in terms of 'accountability' and 'representativeness' . A close examination of these two factors is essential if one is to gain insight into the current condition of the public art institutions. This research is an attempt to understand the history and the current nature of the shifting relationship between the art institutions and the 'public' in South Africa. A further goal is to assess the extent to which concepts that are valid within the realm of the polity can be transposed into the cultural realm: A tendency prevalent within the cultural debate in South Africa during the 1980's. The emphasis of this mini thesis is on the artworld's perception of its social role. I therefore look at the way changing attitudes are reflected in the statements and writing of leading figures within this sector. The method is to critically analyse texts that pertain to my chosen area of research.
- Full Text:
- Date Issued: 1993
Southern African Journal of Gerontology, volume 2, number 1, April 1993
- Ferreira, Monica (editor), Møller, Valerie (editor), HSRC/UCT Centre for Gerontology
- Authors: Ferreira, Monica (editor) , Møller, Valerie (editor) , HSRC/UCT Centre for Gerontology
- Date: 1993
- Subjects: Gerontology -- South Africa , Older people -- Care -- South Africa
- Language: English
- Type: Text
- Identifier: vital:8066 , http://hdl.handle.net/10962/d1012668
- Description: The second number of SAJG again presents knowledge on ageing and the aged which can be useful in the development of better practices and the formulation of better policies in southern African countries. A focus of the articles in this number is on housing and living arrangements. Nyanguru and Peil writing on Zimbabwe give a finely detailed description of the housing situation of the elderly population using survey material. They draw on comparisons with other developing contexts to place the Zimbabwean housing situation in perspective. At the outset, the authors note that the impact of disability on the elderly is directly related to the nature and quality of housing. In conclusion to their overview of urban and rural housing circumstances. they recommend a more appropriate housing policy for the elderly which makes provision for home maintenance and home-help services to assist the elderly to stay in their homes. Moller re-analyses data collected for South Africa's baseline study of the elderly to explore the possible benefits for South Africa's elderly when they live with adult children. Her comparative case studies are based on the assumption that black elders might prefer to live with sons as traditional custom dictates and whites would usually choose to live independently according to Western custom. Chen systematically explores the question of which children co-reside with elderly parents in Taiwan using a large national database and sophisticated multivariate analyses. He also raises the question whether filial piety is on the decline when children no longer co-reside with their parents. The last article in this issue picks up a subject relating to quality of life-a topic introduced in an article in the first issue of SAJG. Authors Gillespie and Louw wish to re-open the debate on activity and quality of life. They pose the provocative question: Does a decline in activity in the elderly really dampen morale? Preliminary results from the pilot study undertaken by the authors reported in the article yielded inconclusive results. However the pilot study involved only a small sample and is presented to make the point and whet our appetite for further research and debate. In support of Gillespie and Louw's call to re-open the debate on the activity question we contribute further South African evidence which allows for various interpretations
- Full Text:
- Date Issued: 1993
- Authors: Ferreira, Monica (editor) , Møller, Valerie (editor) , HSRC/UCT Centre for Gerontology
- Date: 1993
- Subjects: Gerontology -- South Africa , Older people -- Care -- South Africa
- Language: English
- Type: Text
- Identifier: vital:8066 , http://hdl.handle.net/10962/d1012668
- Description: The second number of SAJG again presents knowledge on ageing and the aged which can be useful in the development of better practices and the formulation of better policies in southern African countries. A focus of the articles in this number is on housing and living arrangements. Nyanguru and Peil writing on Zimbabwe give a finely detailed description of the housing situation of the elderly population using survey material. They draw on comparisons with other developing contexts to place the Zimbabwean housing situation in perspective. At the outset, the authors note that the impact of disability on the elderly is directly related to the nature and quality of housing. In conclusion to their overview of urban and rural housing circumstances. they recommend a more appropriate housing policy for the elderly which makes provision for home maintenance and home-help services to assist the elderly to stay in their homes. Moller re-analyses data collected for South Africa's baseline study of the elderly to explore the possible benefits for South Africa's elderly when they live with adult children. Her comparative case studies are based on the assumption that black elders might prefer to live with sons as traditional custom dictates and whites would usually choose to live independently according to Western custom. Chen systematically explores the question of which children co-reside with elderly parents in Taiwan using a large national database and sophisticated multivariate analyses. He also raises the question whether filial piety is on the decline when children no longer co-reside with their parents. The last article in this issue picks up a subject relating to quality of life-a topic introduced in an article in the first issue of SAJG. Authors Gillespie and Louw wish to re-open the debate on activity and quality of life. They pose the provocative question: Does a decline in activity in the elderly really dampen morale? Preliminary results from the pilot study undertaken by the authors reported in the article yielded inconclusive results. However the pilot study involved only a small sample and is presented to make the point and whet our appetite for further research and debate. In support of Gillespie and Louw's call to re-open the debate on the activity question we contribute further South African evidence which allows for various interpretations
- Full Text:
- Date Issued: 1993
Southern African Journal of Gerontology, volume 2, number 2, October 1993
- Ferreira, Monica (editor), Møller, Valerie (editor), HSRC/UCT Centre for Gerontology
- Authors: Ferreira, Monica (editor) , Møller, Valerie (editor) , HSRC/UCT Centre for Gerontology
- Date: 1993
- Subjects: Gerontology -- South Africa , Older people -- Care -- South Africa
- Language: English
- Type: Text
- Identifier: vital:8067 , http://hdl.handle.net/10962/d1012859
- Description: Care of the elderly in the community. No society or government can offer total care for all elderly people in the population - no matter how developed or wealthy the country is. The financial and manpower implications of doing so would be enormous. This fact particularly applies to states in southern Africa, where a large proportion of the populations comprise poor or indigent persons. What this means is that a great deal of the responsibility for the care of these persons devolves upon caregivers in the community, usually the family. The capacity of such caregivers to render care, albeit at a subsistence level and in a piecemeal manner, must be supported. It is encouraging to note that there are local initiatives in this regard- even in the most impoverished squatter camps in South Africa. In such cases people come together in informal groups to help and support one another. The Black Pensioners' Association of Khayelitsha is one such group. Another way in which people help one another is through the practice of stokvels, where individuals put money into an informal joint banking system, and take turns in accessing large amounts of money for major purchases. Despite common understanding in official planning circles that people should themselves mainly take responsibility for their care, a large commitment nevertheless rests with the state. The state is committed to a large number of its citizens who are elderly, needy, and must be provided for. Such provision does not stop with the payment of a social pension. The primary units of care will remain the family and the community. The aim should be to assist the elderly to remain living independently within the community for as long as possible, despite disability and frailty where these conditions are present. The state should target its endeavours in this direction. There are many ways in which this can be done, e.g. through the provision of financial and other support to informal caregivers, and the rendering of geriatric nursing services and home-help services. could easily be implemented in southern African countries. Regular physical examinations and attention to the nutritional needs of older persons are important, for this can prevent many forms of ill health. This is where research comes in. We need to investigate practical and affordable ways of enhancing the health and welfare of elderly persons in our own context, i.e. in southern Africa countries. The articles in this number of SAJG point a way in this direction. , This issue: In an article on community involvement in health (CIH), Hildebrandt offers valuable suggestions based on her experience with a demonstration project in a South African black urban settlement. She shows how the situation of township residents can be improved by actively involving a community in practical endeavours, e.g. starting nutrition and reading programmes, and a basic health-screening programme. The project which she describes can serve as a model for similar projects in other developing communities. McCallum and Mathers present a paradigm for health services which, although developed in Australia, has wide relevance and should be taken into account in all planning for the aged. The authors demonstrate that a concomitant effect of a general improvement in the health of older persons gained by better health care is, paradoxically, an increased rate of disability and physical frailty. The authors point out that the burden of these disabilities has largely to be borne by informal caregivers at home. The article by Visser, van Wyk, Senekal and Uys deals with an entirely different area of ageing: the clothing needs and preferences of older women. This subject is not often dealt with in gerontological literature; to our knowledge this is the first article on this topic in southern Africa. The article presents some interesting findings. New sections: Two new sections are included in this number of SAJG. A section under the rubric Forum has been added. The section is intended to include reviews and overviews of current knowledge and advanced thinking on specific topics or subject areas in gerontology. The first contribution printed in Forum is a brief guide to the biological basis of ageing. In his guide Louw offers a unified hypothesis of the biology of ageing. The number also includes a correspondence section for the first time. A letter to the editor and a reply, in which the writers give their views on the measurement of successful ageing, have been printed. It is appropriate that SAJG, regarded as the most important peer-reviewed gerontology journal in Africa, should encourage high-level argument and polemics. Further responses to published material are therefore welcomed.
- Full Text:
- Date Issued: 1993
- Authors: Ferreira, Monica (editor) , Møller, Valerie (editor) , HSRC/UCT Centre for Gerontology
- Date: 1993
- Subjects: Gerontology -- South Africa , Older people -- Care -- South Africa
- Language: English
- Type: Text
- Identifier: vital:8067 , http://hdl.handle.net/10962/d1012859
- Description: Care of the elderly in the community. No society or government can offer total care for all elderly people in the population - no matter how developed or wealthy the country is. The financial and manpower implications of doing so would be enormous. This fact particularly applies to states in southern Africa, where a large proportion of the populations comprise poor or indigent persons. What this means is that a great deal of the responsibility for the care of these persons devolves upon caregivers in the community, usually the family. The capacity of such caregivers to render care, albeit at a subsistence level and in a piecemeal manner, must be supported. It is encouraging to note that there are local initiatives in this regard- even in the most impoverished squatter camps in South Africa. In such cases people come together in informal groups to help and support one another. The Black Pensioners' Association of Khayelitsha is one such group. Another way in which people help one another is through the practice of stokvels, where individuals put money into an informal joint banking system, and take turns in accessing large amounts of money for major purchases. Despite common understanding in official planning circles that people should themselves mainly take responsibility for their care, a large commitment nevertheless rests with the state. The state is committed to a large number of its citizens who are elderly, needy, and must be provided for. Such provision does not stop with the payment of a social pension. The primary units of care will remain the family and the community. The aim should be to assist the elderly to remain living independently within the community for as long as possible, despite disability and frailty where these conditions are present. The state should target its endeavours in this direction. There are many ways in which this can be done, e.g. through the provision of financial and other support to informal caregivers, and the rendering of geriatric nursing services and home-help services. could easily be implemented in southern African countries. Regular physical examinations and attention to the nutritional needs of older persons are important, for this can prevent many forms of ill health. This is where research comes in. We need to investigate practical and affordable ways of enhancing the health and welfare of elderly persons in our own context, i.e. in southern Africa countries. The articles in this number of SAJG point a way in this direction. , This issue: In an article on community involvement in health (CIH), Hildebrandt offers valuable suggestions based on her experience with a demonstration project in a South African black urban settlement. She shows how the situation of township residents can be improved by actively involving a community in practical endeavours, e.g. starting nutrition and reading programmes, and a basic health-screening programme. The project which she describes can serve as a model for similar projects in other developing communities. McCallum and Mathers present a paradigm for health services which, although developed in Australia, has wide relevance and should be taken into account in all planning for the aged. The authors demonstrate that a concomitant effect of a general improvement in the health of older persons gained by better health care is, paradoxically, an increased rate of disability and physical frailty. The authors point out that the burden of these disabilities has largely to be borne by informal caregivers at home. The article by Visser, van Wyk, Senekal and Uys deals with an entirely different area of ageing: the clothing needs and preferences of older women. This subject is not often dealt with in gerontological literature; to our knowledge this is the first article on this topic in southern Africa. The article presents some interesting findings. New sections: Two new sections are included in this number of SAJG. A section under the rubric Forum has been added. The section is intended to include reviews and overviews of current knowledge and advanced thinking on specific topics or subject areas in gerontology. The first contribution printed in Forum is a brief guide to the biological basis of ageing. In his guide Louw offers a unified hypothesis of the biology of ageing. The number also includes a correspondence section for the first time. A letter to the editor and a reply, in which the writers give their views on the measurement of successful ageing, have been printed. It is appropriate that SAJG, regarded as the most important peer-reviewed gerontology journal in Africa, should encourage high-level argument and polemics. Further responses to published material are therefore welcomed.
- Full Text:
- Date Issued: 1993
Studies in fuzzy groups
- Authors: Makamba, B B
- Date: 1993
- Subjects: Mathematics Fuzzy sets Fuzzy systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5415 , http://hdl.handle.net/10962/d1005229
- Description: In this thesis we first extend the notion of fuzzy normality to the notion of normality of a fuzzy subgroup in another fuzzy group. This leads to the study of normal series of fuzzy subgroups, and this study includes solvable and nilpotent fuzzy groups, and the fuzzy version of the Jordan-Hõlder Theorem. Furthermore we use the notion of normality to study products and direct products of fuzzy subgroups. We present a notion of fuzzy isomorphism which enables us to state and prove the three well-known isomorphism theorems and the fact that the internal direct product of two normal fuzzy subgroups is isomorphic to the external direct product of the same fuzzy subgroups. A brief discussion on fuzzy subgroups generated by fuzzy subsets is also presented, and this leads to the fuzzy version of the Basis Theorem. Finally, the notion of direct product enables us to study decomposable and indecomposable fuzzy subgroups, and this study includes the fuzzy version of the Remak-Krull-Schmidt Theorem.
- Full Text:
- Date Issued: 1993
- Authors: Makamba, B B
- Date: 1993
- Subjects: Mathematics Fuzzy sets Fuzzy systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5415 , http://hdl.handle.net/10962/d1005229
- Description: In this thesis we first extend the notion of fuzzy normality to the notion of normality of a fuzzy subgroup in another fuzzy group. This leads to the study of normal series of fuzzy subgroups, and this study includes solvable and nilpotent fuzzy groups, and the fuzzy version of the Jordan-Hõlder Theorem. Furthermore we use the notion of normality to study products and direct products of fuzzy subgroups. We present a notion of fuzzy isomorphism which enables us to state and prove the three well-known isomorphism theorems and the fact that the internal direct product of two normal fuzzy subgroups is isomorphic to the external direct product of the same fuzzy subgroups. A brief discussion on fuzzy subgroups generated by fuzzy subsets is also presented, and this leads to the fuzzy version of the Basis Theorem. Finally, the notion of direct product enables us to study decomposable and indecomposable fuzzy subgroups, and this study includes the fuzzy version of the Remak-Krull-Schmidt Theorem.
- Full Text:
- Date Issued: 1993
Studies on dune rehabilitation techniques for mined areas at Richards Bay, Natal
- Authors: Moll, John Bingham
- Date: 1993
- Subjects: Restoration ecology -- South Africa -- KwaZulu-Natal -- Richards Bay , Sand dune ecology -- South Africa -- KwaZulu-Natal -- Richards Bay , Sand dunes -- South Africa -- KwaZulu-Natal -- Richards Bay , Mineral industries -- Environmental aspects -- South Africa -- KwaZulu-Natal -- Richards Bay
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4235 , http://hdl.handle.net/10962/d1003841
- Description: Rehabilitation is a dynamic process influenced by factors related to more than one field of ecology. It is therefore necessary to consider all these components when assessing the rehabilitation, although in the initial stages the successful revegetation of the disturbed areas is the most important criterion. Richards Bay Minerals, on whose mining site this project was carried out, is dredge mining heavy minerals on the north coast of Natal, where they have rehabilitated mined areas since 1978. This project has been carried out to establish: 1) The success of their dune forest rehabilitation using quantitative techniques. 2) The available seed bank in their rehabilitation stands. 3) The similarities in the succession taking place in rehabilitation stands compared to the revegetated stands in the vicinity of Richards Bay. 4) The best methods for creating alternative vegetation communities, especially grasslands, with a high species diversity on the mined tailings. This study reviews only the success of rehabilitation of the natural vegetation but other studies focusing on the insect, reptile, mammal and bird populations are also being undertaken by other researchers. No particular method of determining the success of vegetation rehabilitation has been chosen by restoration ecologists. Therefore in this study a broad range of quantitative techniques were used to show whether successional changes are occurring in the vegetation and physical environment. The results obtained from sampling the rehabilitated vegetation have shown that both the species richness and diversity are increasing as the returned vegetation matures. Levels of soil properties such as Sodium, Phosphate, Calcium and percentage organic matter have also risen with increasing stand age. Community complexity is also increasing with stand age, and TWINSPAN and DECORANA plots have separated out the differently aged stands based on their differences. A "pilot" study was done on the seed bank present in the rehabilitation stands. This has shown the presence of large amounts of early successional, mostly herbaceous species. Seeds of later successional and woody species were scarce which may be a result of the sampling intensity used. However seeds of late successional ground cover species were found in the older stands. Comparisons between the natural revegetation of disturbed areas in the vicinity of Richards Bay and the rehabilitation stands revealed similarities in both species composition and complexity. Species richness and diversity values are comparatively similar for the younger revegetated and older rehabilitation stands, and lWlNSPAN and DECORANA analysis techniques clustered the samples recorded from these areas in close proximity on their relative plots. The oldest revegetated sites contain a number of species found in the rehabilitated vegetation but as Acacia karroo has thinned-out in these stands many of these other species are now mature individuals. Attempts at rehabilitating an area of grassland at Richards Bay Minerals has not produced satisfactory species diversity and experimental manipulations were used to try and increase the diversity of the existing Eragrostis curvula dominated community. Of the several treatments used for the manipulation, a combination of burning and further topsoiling was the most successful in reducing Eragrostis importance and in increasing the species richness. Grassland topsoil spread directly onto the bare tailings produced an extensive vegetation covering over a short period but species richness was not significantly greater than for the existing Eragrostis dominated grassland, and further treatments and management needs to continue if this technique is to be employed. Only a limited amount of alien infestation of the rehabilitated areas was evident from the sampling undertaken during this research. As the removal of alien plants is an ongoing process and the rehabilitation stands are continuously monitored to identify any new invaders, this is not expected to become a problem. From the results of work done overseas and the rehabilitation carried out in South Africa it appears that it is possible to return natural vegetation communities on mined areas. That this is a lengthy process is to be expected but by manipulating the vegetation and continuously monitoring the process it may be possible to speed up development. Areas in need of further research have been identified based on the findings of this project. This will help to reinforce the undertaking of management proposals that will enhance the vegetation recovery and the success of the rehabilitation programme.
- Full Text:
- Date Issued: 1993
- Authors: Moll, John Bingham
- Date: 1993
- Subjects: Restoration ecology -- South Africa -- KwaZulu-Natal -- Richards Bay , Sand dune ecology -- South Africa -- KwaZulu-Natal -- Richards Bay , Sand dunes -- South Africa -- KwaZulu-Natal -- Richards Bay , Mineral industries -- Environmental aspects -- South Africa -- KwaZulu-Natal -- Richards Bay
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4235 , http://hdl.handle.net/10962/d1003841
- Description: Rehabilitation is a dynamic process influenced by factors related to more than one field of ecology. It is therefore necessary to consider all these components when assessing the rehabilitation, although in the initial stages the successful revegetation of the disturbed areas is the most important criterion. Richards Bay Minerals, on whose mining site this project was carried out, is dredge mining heavy minerals on the north coast of Natal, where they have rehabilitated mined areas since 1978. This project has been carried out to establish: 1) The success of their dune forest rehabilitation using quantitative techniques. 2) The available seed bank in their rehabilitation stands. 3) The similarities in the succession taking place in rehabilitation stands compared to the revegetated stands in the vicinity of Richards Bay. 4) The best methods for creating alternative vegetation communities, especially grasslands, with a high species diversity on the mined tailings. This study reviews only the success of rehabilitation of the natural vegetation but other studies focusing on the insect, reptile, mammal and bird populations are also being undertaken by other researchers. No particular method of determining the success of vegetation rehabilitation has been chosen by restoration ecologists. Therefore in this study a broad range of quantitative techniques were used to show whether successional changes are occurring in the vegetation and physical environment. The results obtained from sampling the rehabilitated vegetation have shown that both the species richness and diversity are increasing as the returned vegetation matures. Levels of soil properties such as Sodium, Phosphate, Calcium and percentage organic matter have also risen with increasing stand age. Community complexity is also increasing with stand age, and TWINSPAN and DECORANA plots have separated out the differently aged stands based on their differences. A "pilot" study was done on the seed bank present in the rehabilitation stands. This has shown the presence of large amounts of early successional, mostly herbaceous species. Seeds of later successional and woody species were scarce which may be a result of the sampling intensity used. However seeds of late successional ground cover species were found in the older stands. Comparisons between the natural revegetation of disturbed areas in the vicinity of Richards Bay and the rehabilitation stands revealed similarities in both species composition and complexity. Species richness and diversity values are comparatively similar for the younger revegetated and older rehabilitation stands, and lWlNSPAN and DECORANA analysis techniques clustered the samples recorded from these areas in close proximity on their relative plots. The oldest revegetated sites contain a number of species found in the rehabilitated vegetation but as Acacia karroo has thinned-out in these stands many of these other species are now mature individuals. Attempts at rehabilitating an area of grassland at Richards Bay Minerals has not produced satisfactory species diversity and experimental manipulations were used to try and increase the diversity of the existing Eragrostis curvula dominated community. Of the several treatments used for the manipulation, a combination of burning and further topsoiling was the most successful in reducing Eragrostis importance and in increasing the species richness. Grassland topsoil spread directly onto the bare tailings produced an extensive vegetation covering over a short period but species richness was not significantly greater than for the existing Eragrostis dominated grassland, and further treatments and management needs to continue if this technique is to be employed. Only a limited amount of alien infestation of the rehabilitated areas was evident from the sampling undertaken during this research. As the removal of alien plants is an ongoing process and the rehabilitation stands are continuously monitored to identify any new invaders, this is not expected to become a problem. From the results of work done overseas and the rehabilitation carried out in South Africa it appears that it is possible to return natural vegetation communities on mined areas. That this is a lengthy process is to be expected but by manipulating the vegetation and continuously monitoring the process it may be possible to speed up development. Areas in need of further research have been identified based on the findings of this project. This will help to reinforce the undertaking of management proposals that will enhance the vegetation recovery and the success of the rehabilitation programme.
- Full Text:
- Date Issued: 1993
The biological control of Hakea sericea Schrader by the Hakea seed-moth, Carposina autologa Meyrick, in South Africa
- Authors: Gordon, Antony John
- Date: 1993
- Subjects: Weeds -- Biological control -- South Africa , Moths , Carposinidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5648 , http://hdl.handle.net/10962/d1005330 , Weeds -- Biological control -- South Africa , Moths , Carposinidae
- Description: Hakea sericea Schrader was introduced to South Africa from Australia and has become a major problem in nearly all the coastal mountain ranges of the Cape Province. The hakea seed-moth, Carposina autologa Meyrick was released in South Africa for the biological control of H. sericea. The impact of the moth on the canopy-stored seeds of H. sericea was evaluated at two study sites in the south-western Cape over three years. The moth has reduced the accumulated seeds at the two study sites by 59.4% and 42.6%, respectively. The moth has shown a surprising ability to disperse and establish new colonies at low population levels. Factors contributing to the slow colonization of C. autologa in South Africa was investigated. The moths appear to be unable to distinguish between healthy and previously attacked fruits; 42.5% of the eggs were laid on attacked fruits. Only 13.1% of the healthy fruits with eggs yielded mature larvae. The high pre-penetration mortality found in the present study is similar to that found in Australia. The effect of the indigenous fungus, Colletotrichum gloeosporioides (Penz.) Sacc., on both H. sericea and C. autologa was investigated. H. sericea trees and branches that die as a result of fungus cause the accumulated fruits on the affected trees or branches to dehisce. This seed loss occurs at a crucial stage during C. autologa larval development. Only 42.1% and 33.0% of the trees were found to be healthy at the two study sites, respectively. One seed crop will always be available for regeneration, since recruitment is linked to fires, and wild-fires occur at a stage when the latest seed crop has escaped attack by c. autologa. C. autologa was released at six sites in the south-western Cape by attaching egg-bearing follicles to healthy fruits in the field. Three release sites were evaluated the year following release to determine whether the moth established or not. The role of C. autologa in the H. sericea biological control programme is discussed. Although seed destruction by C. autologa is not severe, it is expected to contribute to the control of H. sericea.
- Full Text:
- Date Issued: 1993
- Authors: Gordon, Antony John
- Date: 1993
- Subjects: Weeds -- Biological control -- South Africa , Moths , Carposinidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5648 , http://hdl.handle.net/10962/d1005330 , Weeds -- Biological control -- South Africa , Moths , Carposinidae
- Description: Hakea sericea Schrader was introduced to South Africa from Australia and has become a major problem in nearly all the coastal mountain ranges of the Cape Province. The hakea seed-moth, Carposina autologa Meyrick was released in South Africa for the biological control of H. sericea. The impact of the moth on the canopy-stored seeds of H. sericea was evaluated at two study sites in the south-western Cape over three years. The moth has reduced the accumulated seeds at the two study sites by 59.4% and 42.6%, respectively. The moth has shown a surprising ability to disperse and establish new colonies at low population levels. Factors contributing to the slow colonization of C. autologa in South Africa was investigated. The moths appear to be unable to distinguish between healthy and previously attacked fruits; 42.5% of the eggs were laid on attacked fruits. Only 13.1% of the healthy fruits with eggs yielded mature larvae. The high pre-penetration mortality found in the present study is similar to that found in Australia. The effect of the indigenous fungus, Colletotrichum gloeosporioides (Penz.) Sacc., on both H. sericea and C. autologa was investigated. H. sericea trees and branches that die as a result of fungus cause the accumulated fruits on the affected trees or branches to dehisce. This seed loss occurs at a crucial stage during C. autologa larval development. Only 42.1% and 33.0% of the trees were found to be healthy at the two study sites, respectively. One seed crop will always be available for regeneration, since recruitment is linked to fires, and wild-fires occur at a stage when the latest seed crop has escaped attack by c. autologa. C. autologa was released at six sites in the south-western Cape by attaching egg-bearing follicles to healthy fruits in the field. Three release sites were evaluated the year following release to determine whether the moth established or not. The role of C. autologa in the H. sericea biological control programme is discussed. Although seed destruction by C. autologa is not severe, it is expected to contribute to the control of H. sericea.
- Full Text:
- Date Issued: 1993
The biology of a facultative hyperparasitoid, Tetrastichus Howardi Olliff (Hymenoptera : Eulophidae), and its potential as a biocontrol agent of lepidopterous stem borers
- Authors: Moore, Sean Douglas
- Date: 1993
- Subjects: Eulophidae , Hymenoptera , Cephidae -- Biological control , Pests -- Biological control
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5649 , http://hdl.handle.net/10962/d1005331 , Eulophidae , Hymenoptera , Cephidae -- Biological control , Pests -- Biological control
- Description: The gregarious pupal endoparasitoid, Tetrastichus howardi Olliff (Hymenoptera: Eulophidae), was introduced into South Africa as a biocontrol agent against the maize and the sorghum stem borers, Busseola fusca Fuller and Chilo partellus Swinhoe. Preovipositional behaviour, ovipositional behaviour, development, fertility, sex-ratio, and longevity were studied in the laboratory. A complex courtship behaviour was observed, however 35.3% of females were mated before emergence from the host pupa. Preoviposition period ranged from 100 mins up to 5 days. Host searching time in Petri dishes was shorter for lepidopteran pupae than for their parasitoid pupae, and shortest when T. howardi had previously experienced the host. Duration of oviposition was significantly longer in the lepidopteran pupae than in the smaller tachinid puparia. T. howardi showed no difference in preference for hosts of different ages. The lepidopteran hosts were preferred to their parasitoids. If T. howardi had previously experienced a certain host its pereference for that host tended to increase, but not significantly. When reared on a certain host, the preference for that host did increase. The parasitoid was able to discriminate between parasitzed and unparasitzed pupae although this ability developed only 2 days after the pupa was parasitized. Cotesia sesamiae Cameron, the main indigenous parasitoid of B. fusca and C. partellus, was not attacked by T howardi. The total duration of development from egg deposition to the adult stage ranged from 18 to 26 days at 24°C and 60% RH. Emergence of adults began after first light, mean emergence time in winter being 09h00. Emergence rate of T. howardi from parasitized hosts, and mortality rate of parasitized hosts, was higher for C. partellus and H. armigera than for Eldana saccharina Walker and Palexorista laxa Curran. This decreased for C. partellus and H. armigera when superparasitized. A strong correlation existed between total parasitoids emerging from a host and percentage of females. When a lepidopteran pupa was parasitized by a single T. howardi female, 55 progeny emerged of which 94% were females. Larger females showed greater fertility and also produced a higher percentage of females. Younger hosts were more suitable for development of T. howardi. Females lived for 5.4 to 52.5 days, and males lived for 3.1 to 28.6 days, depending on presence or absence of food, water and hosts. Reasons for releasing T. howardi in the field are discussed. Only 2 recoveries of parasitized C. partellus pupae were made from the field.
- Full Text:
- Date Issued: 1993
- Authors: Moore, Sean Douglas
- Date: 1993
- Subjects: Eulophidae , Hymenoptera , Cephidae -- Biological control , Pests -- Biological control
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5649 , http://hdl.handle.net/10962/d1005331 , Eulophidae , Hymenoptera , Cephidae -- Biological control , Pests -- Biological control
- Description: The gregarious pupal endoparasitoid, Tetrastichus howardi Olliff (Hymenoptera: Eulophidae), was introduced into South Africa as a biocontrol agent against the maize and the sorghum stem borers, Busseola fusca Fuller and Chilo partellus Swinhoe. Preovipositional behaviour, ovipositional behaviour, development, fertility, sex-ratio, and longevity were studied in the laboratory. A complex courtship behaviour was observed, however 35.3% of females were mated before emergence from the host pupa. Preoviposition period ranged from 100 mins up to 5 days. Host searching time in Petri dishes was shorter for lepidopteran pupae than for their parasitoid pupae, and shortest when T. howardi had previously experienced the host. Duration of oviposition was significantly longer in the lepidopteran pupae than in the smaller tachinid puparia. T. howardi showed no difference in preference for hosts of different ages. The lepidopteran hosts were preferred to their parasitoids. If T. howardi had previously experienced a certain host its pereference for that host tended to increase, but not significantly. When reared on a certain host, the preference for that host did increase. The parasitoid was able to discriminate between parasitzed and unparasitzed pupae although this ability developed only 2 days after the pupa was parasitized. Cotesia sesamiae Cameron, the main indigenous parasitoid of B. fusca and C. partellus, was not attacked by T howardi. The total duration of development from egg deposition to the adult stage ranged from 18 to 26 days at 24°C and 60% RH. Emergence of adults began after first light, mean emergence time in winter being 09h00. Emergence rate of T. howardi from parasitized hosts, and mortality rate of parasitized hosts, was higher for C. partellus and H. armigera than for Eldana saccharina Walker and Palexorista laxa Curran. This decreased for C. partellus and H. armigera when superparasitized. A strong correlation existed between total parasitoids emerging from a host and percentage of females. When a lepidopteran pupa was parasitized by a single T. howardi female, 55 progeny emerged of which 94% were females. Larger females showed greater fertility and also produced a higher percentage of females. Younger hosts were more suitable for development of T. howardi. Females lived for 5.4 to 52.5 days, and males lived for 3.1 to 28.6 days, depending on presence or absence of food, water and hosts. Reasons for releasing T. howardi in the field are discussed. Only 2 recoveries of parasitized C. partellus pupae were made from the field.
- Full Text:
- Date Issued: 1993
The biology of Palexorista laxa (Curran) (Diptera : Tachinidae) : an internal larval parasitoid of Heliothis armigera (Hübner) Lepidoptera : Noctuidae)
- Authors: Van Heerden, Desireé
- Date: 1993
- Subjects: Tachinidae , Helicoverpa armigera -- Parasites -- Life cycles , Noctuidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5650 , http://hdl.handle.net/10962/d1005332 , Tachinidae , Helicoverpa armigera -- Parasites -- Life cycles , Noctuidae
- Description: The Tachinid fly, Palexorista laxa (Curran) is an important parasitoid of Heliothis armigera (Hubner) in Africa and India. The biological characteristics of the parasitoid were studied with an emphasis on its host instar preference, host range, seasonality and percentage parasitism. The developmental stages were also studied and described. A high host mortality (48%-100%) due to parasite attack occurred when small larvae were parasitised (2nd & 3rd instars). A preference for the 4th and 5th host instars was shown by the flies. P. laxa was found to be a non-specific parasitoid and parasitised a number of lepidopterous larvae in the laboratory including Busseola fusca (Fuller), Chilo partellus (Swinhoe) and Eldana saccharina Walker, but preferred Ii. armigera. The percentage parasitism on H. armigera in the field was variable peaking at 48% in 1988/89. Of the various parasitoids recorded from H. armigera on sunflower P. laxa was by far the most abundant. Mating occurred immediately after emergence with the males emerging a day earlier than the females. Males were capable of multiple matings whereas females mated only once in a lifetime. P. laxa females produced incubated macrotype eggs which hatched almost immediately after oviposition. The duration of development of the incubated egg and larval stage was 6,7 days, the pupa 10,4 days for females and 9,4 days for males, and the adult lived up to 50 days at 25°C. A reduction in pupal weight, an increase in the duration of the pupal stage and higher pupal mortality accompanied an increase in density of parasitoids per host. A linear relationship was shown between adult mass and number of ovarioles and eggs in P. laxa females. The oviposition period was 26,9 days with a high variation in daily progeny production. The total fertility per female was 126,3 puparia. "Inexperienced" females deposited incubated eggs on all parts of the host body while "experienced" females confined oviposition to the head and thorax. P. laxa females did not discriminate between previously parasitised and non-parasitised hosts. The effect of temperature on larval and pupal survival and development time was studied at 20°, 22°, 25°, 28°and 30°C. As expected, duration of development decreased with an increase in temperature, and there was a reduction in mortality.
- Full Text:
- Date Issued: 1993
- Authors: Van Heerden, Desireé
- Date: 1993
- Subjects: Tachinidae , Helicoverpa armigera -- Parasites -- Life cycles , Noctuidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5650 , http://hdl.handle.net/10962/d1005332 , Tachinidae , Helicoverpa armigera -- Parasites -- Life cycles , Noctuidae
- Description: The Tachinid fly, Palexorista laxa (Curran) is an important parasitoid of Heliothis armigera (Hubner) in Africa and India. The biological characteristics of the parasitoid were studied with an emphasis on its host instar preference, host range, seasonality and percentage parasitism. The developmental stages were also studied and described. A high host mortality (48%-100%) due to parasite attack occurred when small larvae were parasitised (2nd & 3rd instars). A preference for the 4th and 5th host instars was shown by the flies. P. laxa was found to be a non-specific parasitoid and parasitised a number of lepidopterous larvae in the laboratory including Busseola fusca (Fuller), Chilo partellus (Swinhoe) and Eldana saccharina Walker, but preferred Ii. armigera. The percentage parasitism on H. armigera in the field was variable peaking at 48% in 1988/89. Of the various parasitoids recorded from H. armigera on sunflower P. laxa was by far the most abundant. Mating occurred immediately after emergence with the males emerging a day earlier than the females. Males were capable of multiple matings whereas females mated only once in a lifetime. P. laxa females produced incubated macrotype eggs which hatched almost immediately after oviposition. The duration of development of the incubated egg and larval stage was 6,7 days, the pupa 10,4 days for females and 9,4 days for males, and the adult lived up to 50 days at 25°C. A reduction in pupal weight, an increase in the duration of the pupal stage and higher pupal mortality accompanied an increase in density of parasitoids per host. A linear relationship was shown between adult mass and number of ovarioles and eggs in P. laxa females. The oviposition period was 26,9 days with a high variation in daily progeny production. The total fertility per female was 126,3 puparia. "Inexperienced" females deposited incubated eggs on all parts of the host body while "experienced" females confined oviposition to the head and thorax. P. laxa females did not discriminate between previously parasitised and non-parasitised hosts. The effect of temperature on larval and pupal survival and development time was studied at 20°, 22°, 25°, 28°and 30°C. As expected, duration of development decreased with an increase in temperature, and there was a reduction in mortality.
- Full Text:
- Date Issued: 1993
The biotechnology of effluent-grown Spirulina, and application in aquaculture nutrition
- Authors: Maart, Brenton Ashley
- Date: 1993
- Subjects: Aquaculture , Spirulina , Algae -- Biotechnology , Fishes -- Feeding and feeds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4050 , http://hdl.handle.net/10962/d1004111 , Aquaculture , Spirulina , Algae -- Biotechnology , Fishes -- Feeding and feeds
- Description: The biotechnology of production and utilisation of the cyanobacterium Spirulina has been well documented. Research has centred mainly on application in human and animal nutrition, and has been motivated by the high protein, vitamin, fatty acid and growth factor contents. The main obstacle in realising the full potential of this feed source has been the high production costs associated with its mass culture in defined media. The observation of blooms of Spirulina in tannery effluent evaporation ponds in Wellington, South Africa, prompted this investigation into the harvesting, and nutritional and toxicological evaluation of this potentially low-cost production system, with the ultimate aim of using the product in aquaculture rations. An investigation of the chemical gradient along the evaporation cascade showed a positive correlation between the prevailing chemical conditions and the dominant species populations. A standing crop of 9.5 tonnes/ha of Spirulina was found to be present in the latter alkaline ponds, characterised by relatively lower organic and sulphur contents. Initial harvesting of the biomass was achieved by the design, construction and implementation of a small-scale screen harvest, which yielded a 25 kg (dry weight) crop. A scale-up model was then designed, and implemented in a technical scale harvest, yielding a crop of 250 kg (dry weight). Both these harvests utilised the bloom of surface-autoflocculated biomass. Concentrated cell slurries were sun-dried on muslin beds, and milled to a coarse powder. An evaluation of the harvest revealed a chemical content similar to other published reports of defined media cultures, with the exception of the protein and amino acid contents. The observed lower levels of the latter two are almost certainly due to the sun-drying method employed, known to reduce the protein content due to thermal denaturation. Legislation demands the strict toxicological evaluation of new protein sources, and because of the effluent-nature of the growth medium of this source of Spirulina, its viability lies only in the application as an animal feed or supplement. A range of toxicological tests were chosen that were targeted to elucidate the possible toxicological constraints of this effluentgrown source of protein in animal nutrition. The nucleic acid and pesticide contents of the harvested biomass were within the prescribed safety ranges. Atomic absorption showed minimal accumulation of minerals and heavy metals from the effluent. A bioassay with the brine shrimp Anemia salina showed that the biomass contained no toxicologically active water-soluble components. A short term feeding trial with new-born chicks showed that supplementation with Spirulina had no effect on the growth rates and feed conversion ratios of the different feeding groups. Pathological analyses showed that the liver was the only target organ to elicit a change in response to supplementation of the diets with Spirulina. A general decrease in liver weight was noted, with Cu, Ca, Fe and Zn being significantly accumulated. A histopathological examination however, showed no cellular and functional aberration from the control animals. The toxicological analyses gave the preliminary safe go-ahead for the evaluation of effluent-grown Spirulina in aquaculture nutrition. The South African abalone Haliotis midae, and the rainbow trout Oncorhynchus mykiss were chosen as representative species of edible cultured organisms. The technology for the culture of the perlemoen abalone is being established in South Africa, with the main area of research being the development of an artificial diet for high density culture. A 40 day growth trial demonstrated that lower concentrations of Spirulina supplemented to an agar-based fishmeal diet resulted in growth rates and feed conversion ratios similar to the control fishmeal and purified-casein diets, and thus has application potential in the nutrition of this high-cost marine delicacy. The aquaculture technology of freshwater rainbow trout is already well established. An eight week feeding trial with various concentrations of Spirulina showed that this effluent-grown protein source can partially replace fishmeal in semi-purified diets. Fish fed Spirulina did not exhibit decisive manifestations of toxicity, as determined in a histopathological study. In addition, Spirulina supplementation resulted in enhanced colouration of the skin and flesh, which may have implications in the aesthetic marketing of this sought-after table fish. The primary aim of this preliminary investigation thus concerned the determination of the biotechnological potential of this effluent-source of Spirulina. A technology transfer from the economically unfeasible defined-media culture was implemented. This project is ultimately aimed as a contribution towards the treatment of tannery wastewater, by the removal of contaminants from the effluent in the form of organic biomass.
- Full Text:
- Date Issued: 1993
- Authors: Maart, Brenton Ashley
- Date: 1993
- Subjects: Aquaculture , Spirulina , Algae -- Biotechnology , Fishes -- Feeding and feeds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4050 , http://hdl.handle.net/10962/d1004111 , Aquaculture , Spirulina , Algae -- Biotechnology , Fishes -- Feeding and feeds
- Description: The biotechnology of production and utilisation of the cyanobacterium Spirulina has been well documented. Research has centred mainly on application in human and animal nutrition, and has been motivated by the high protein, vitamin, fatty acid and growth factor contents. The main obstacle in realising the full potential of this feed source has been the high production costs associated with its mass culture in defined media. The observation of blooms of Spirulina in tannery effluent evaporation ponds in Wellington, South Africa, prompted this investigation into the harvesting, and nutritional and toxicological evaluation of this potentially low-cost production system, with the ultimate aim of using the product in aquaculture rations. An investigation of the chemical gradient along the evaporation cascade showed a positive correlation between the prevailing chemical conditions and the dominant species populations. A standing crop of 9.5 tonnes/ha of Spirulina was found to be present in the latter alkaline ponds, characterised by relatively lower organic and sulphur contents. Initial harvesting of the biomass was achieved by the design, construction and implementation of a small-scale screen harvest, which yielded a 25 kg (dry weight) crop. A scale-up model was then designed, and implemented in a technical scale harvest, yielding a crop of 250 kg (dry weight). Both these harvests utilised the bloom of surface-autoflocculated biomass. Concentrated cell slurries were sun-dried on muslin beds, and milled to a coarse powder. An evaluation of the harvest revealed a chemical content similar to other published reports of defined media cultures, with the exception of the protein and amino acid contents. The observed lower levels of the latter two are almost certainly due to the sun-drying method employed, known to reduce the protein content due to thermal denaturation. Legislation demands the strict toxicological evaluation of new protein sources, and because of the effluent-nature of the growth medium of this source of Spirulina, its viability lies only in the application as an animal feed or supplement. A range of toxicological tests were chosen that were targeted to elucidate the possible toxicological constraints of this effluentgrown source of protein in animal nutrition. The nucleic acid and pesticide contents of the harvested biomass were within the prescribed safety ranges. Atomic absorption showed minimal accumulation of minerals and heavy metals from the effluent. A bioassay with the brine shrimp Anemia salina showed that the biomass contained no toxicologically active water-soluble components. A short term feeding trial with new-born chicks showed that supplementation with Spirulina had no effect on the growth rates and feed conversion ratios of the different feeding groups. Pathological analyses showed that the liver was the only target organ to elicit a change in response to supplementation of the diets with Spirulina. A general decrease in liver weight was noted, with Cu, Ca, Fe and Zn being significantly accumulated. A histopathological examination however, showed no cellular and functional aberration from the control animals. The toxicological analyses gave the preliminary safe go-ahead for the evaluation of effluent-grown Spirulina in aquaculture nutrition. The South African abalone Haliotis midae, and the rainbow trout Oncorhynchus mykiss were chosen as representative species of edible cultured organisms. The technology for the culture of the perlemoen abalone is being established in South Africa, with the main area of research being the development of an artificial diet for high density culture. A 40 day growth trial demonstrated that lower concentrations of Spirulina supplemented to an agar-based fishmeal diet resulted in growth rates and feed conversion ratios similar to the control fishmeal and purified-casein diets, and thus has application potential in the nutrition of this high-cost marine delicacy. The aquaculture technology of freshwater rainbow trout is already well established. An eight week feeding trial with various concentrations of Spirulina showed that this effluent-grown protein source can partially replace fishmeal in semi-purified diets. Fish fed Spirulina did not exhibit decisive manifestations of toxicity, as determined in a histopathological study. In addition, Spirulina supplementation resulted in enhanced colouration of the skin and flesh, which may have implications in the aesthetic marketing of this sought-after table fish. The primary aim of this preliminary investigation thus concerned the determination of the biotechnological potential of this effluent-source of Spirulina. A technology transfer from the economically unfeasible defined-media culture was implemented. This project is ultimately aimed as a contribution towards the treatment of tannery wastewater, by the removal of contaminants from the effluent in the form of organic biomass.
- Full Text:
- Date Issued: 1993
The characteristics of some Xhosa dramas
- Authors: Sirayi, Mziwoxolo
- Date: 1993
- Subjects: African literature -- Criticism and interpretation , Xhosa drama -- History and criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3598 , http://hdl.handle.net/10962/d1002173 , African literature -- Criticism and interpretation , Xhosa drama -- History and criticism
- Description: This study aims at highlighting some crucial aspects of Xhosa drama. These aspects are of great significance for the understanding of Xhosa drama. It also aims to historicize and contextualize examinations of traditional Xhosa drama and modern Xhosa drama.
- Full Text:
- Date Issued: 1993
- Authors: Sirayi, Mziwoxolo
- Date: 1993
- Subjects: African literature -- Criticism and interpretation , Xhosa drama -- History and criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3598 , http://hdl.handle.net/10962/d1002173 , African literature -- Criticism and interpretation , Xhosa drama -- History and criticism
- Description: This study aims at highlighting some crucial aspects of Xhosa drama. These aspects are of great significance for the understanding of Xhosa drama. It also aims to historicize and contextualize examinations of traditional Xhosa drama and modern Xhosa drama.
- Full Text:
- Date Issued: 1993
The construction, implementation and evaluation of a transactional analysis stress management course for adolescents
- Authors: Ritchie, Harriet Anne
- Date: 1993
- Subjects: Transactional analysis Stress in adolescence Adolescent psychology Stress management
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1461 , http://hdl.handle.net/10962/d1003342
- Description: Stress is a problem in today's world and adolescents are not exempt from suffering its ill effects. Currently no stress management courses are offered as part of the formal guidance programme in high schools or in the community. This pilot study is an attempt to construct a stress management course based on the concepts of Transactional Analysis. The course was implemented with a multi-racial, standard eight group of nine boys and girls. The course was evaluated qualitatively and quantitatively. The quantitative measures proved to be inappropriate to this study and did not render any useful information. The study found that the scholars expressed that they had changed in their handling of their daily stressors as a result of the course. Personal growth had also taken place. The findings of this research are discussed in terms of the important implications they have for school guidance programmes.
- Full Text:
- Date Issued: 1993
- Authors: Ritchie, Harriet Anne
- Date: 1993
- Subjects: Transactional analysis Stress in adolescence Adolescent psychology Stress management
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1461 , http://hdl.handle.net/10962/d1003342
- Description: Stress is a problem in today's world and adolescents are not exempt from suffering its ill effects. Currently no stress management courses are offered as part of the formal guidance programme in high schools or in the community. This pilot study is an attempt to construct a stress management course based on the concepts of Transactional Analysis. The course was implemented with a multi-racial, standard eight group of nine boys and girls. The course was evaluated qualitatively and quantitatively. The quantitative measures proved to be inappropriate to this study and did not render any useful information. The study found that the scholars expressed that they had changed in their handling of their daily stressors as a result of the course. Personal growth had also taken place. The findings of this research are discussed in terms of the important implications they have for school guidance programmes.
- Full Text:
- Date Issued: 1993
The domestic worker some considerations for law reform
- Meintjes-van der Walt, Lirieka
- Authors: Meintjes-van der Walt, Lirieka
- Date: 1993
- Subjects: Household employees -- Law and legislation -- South Africa , Black people -- Employment -- South Africa , Women -- Employment -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3683 , http://hdl.handle.net/10962/d1003198 , Household employees -- Law and legislation -- South Africa , Black people -- Employment -- South Africa , Women -- Employment -- South Africa
- Description: This thesis examines ways in which domestic workers in South Africa could be included within the scope of existing industrial legislation. At present the legal position of a work force of 862 000 is regulated by the common law contract of service. Socio-economic factors form the background of this investigation,which first sets out to determine whether the common-law contract of employment is capable of equitably regulating the employment relationship. The fallacy of the assumption that individuals agree on the terms of exchange in the employment contract on the basis of juridical equality, and the tenuous nature of the common-law employment relationship in the case of domestic workers are revealed. In the absence of any current statutory minima the employment contract is used to deprive domestic workers of what little protection they enjoy at common law. The two ways in which the individual employee's conditions of service can be protected from terms favouring the stronger of the two contracting parties are discussed. These are collective bargaining and statutory regulation. Difficulties experienced by domestic workers in respect of collective bargaining, whether they be included under the Labour Relations Act or not, are indicated. Proposals for including domestic workers under the Basic Conditions of Employment Act are evaluated in the light of legislation in the United States of America, Zimbabwe, Swaziland and Namibia. Ways of minimum-wage fixing are investigated, and it is concluded that the provisions of the Wage Act could be adapted for domestic workers. The 'unfair labour practice'concept is examined and the implications of its application for the domestic labour sector evaluated. It is recommended that the concept 'fairness' in the Labour Relations Act should apply to domestic workers, but that a code of practice be drafted to provide conceptions of 'fairness' as guidelines for employment behaviour. It is suggested that the parties refer disputes to mediation before being granted access to a Small Labour Court established for this purpose. In conclusion a draft code of practice is presented, as a basis for negotiation at a forum representative of the major actors in the domestic labour arena.
- Full Text:
- Date Issued: 1993
- Authors: Meintjes-van der Walt, Lirieka
- Date: 1993
- Subjects: Household employees -- Law and legislation -- South Africa , Black people -- Employment -- South Africa , Women -- Employment -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3683 , http://hdl.handle.net/10962/d1003198 , Household employees -- Law and legislation -- South Africa , Black people -- Employment -- South Africa , Women -- Employment -- South Africa
- Description: This thesis examines ways in which domestic workers in South Africa could be included within the scope of existing industrial legislation. At present the legal position of a work force of 862 000 is regulated by the common law contract of service. Socio-economic factors form the background of this investigation,which first sets out to determine whether the common-law contract of employment is capable of equitably regulating the employment relationship. The fallacy of the assumption that individuals agree on the terms of exchange in the employment contract on the basis of juridical equality, and the tenuous nature of the common-law employment relationship in the case of domestic workers are revealed. In the absence of any current statutory minima the employment contract is used to deprive domestic workers of what little protection they enjoy at common law. The two ways in which the individual employee's conditions of service can be protected from terms favouring the stronger of the two contracting parties are discussed. These are collective bargaining and statutory regulation. Difficulties experienced by domestic workers in respect of collective bargaining, whether they be included under the Labour Relations Act or not, are indicated. Proposals for including domestic workers under the Basic Conditions of Employment Act are evaluated in the light of legislation in the United States of America, Zimbabwe, Swaziland and Namibia. Ways of minimum-wage fixing are investigated, and it is concluded that the provisions of the Wage Act could be adapted for domestic workers. The 'unfair labour practice'concept is examined and the implications of its application for the domestic labour sector evaluated. It is recommended that the concept 'fairness' in the Labour Relations Act should apply to domestic workers, but that a code of practice be drafted to provide conceptions of 'fairness' as guidelines for employment behaviour. It is suggested that the parties refer disputes to mediation before being granted access to a Small Labour Court established for this purpose. In conclusion a draft code of practice is presented, as a basis for negotiation at a forum representative of the major actors in the domestic labour arena.
- Full Text:
- Date Issued: 1993
The ecology of the South African citrus thrips, Scirtothrips aurantii Faure and its economic implications
- Authors: Gilbert, Martin Jeffray
- Date: 1993
- Subjects: Thrips -- Control -- South Africa Citrus -- Diseases and pests -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5673 , http://hdl.handle.net/10962/d1005358
- Description: The South African Citrus Thrips, Scirtothrips aurantii Faure (Thysanoptera: Thripidae) has been a serious pest of the citrus industry of Southern Africa for over 70 years. It is indigenous to Africa and has no recorded parasitoids and, in most citrus-growing regions, predators are not economically effective. Firstly, in this study, the general ecology of thrips was reviewed along with the recorded history of S. aurantii and its control. Host plant relationships of S. aurantii were then examined and wild hosts were not found to be important in promoting citrus thrips outbreaks in the orchard after flowering. In addition, Scirtothrips dorsalis Hood, which attacks citrus in Asia, was collected for the first time in Africa, but from Castor Oil plant. It is therefore a potential pest of citrus here. Notes on its appearance compared to that of S. aurantii were prepared. Weekly sampling of S. aurantii adults was carried out from June 1984 to May 1990. Population fluctuations were then correlated with phenology of the citrus trees and the direct and indirect effects of weather. Temperature and rainfall were not found to be significantly directly correlated with thrips numbers recorded. However, the indirect effects of rainfall were important in promoting a large winter thrips population in certain years. Relatively high rainfall during March and April compared to that of the previous January and February stimulated atypical flushing of the citrus trees during autumn and the setting of out-of-season fruit. S. aurantii then exploited this unusual food source and high numbers were subsequently recorded in the following winter; as well as in spring. Thus the mild winter climate alone could not suppress thrips numbers at Letaba. Dispersal/Emergence traps, which are used in the U.S.A. for the monitoring of Scirtothrips citri, were evaluated over 24 months, and were effective in recording population peaks of S. aurantii. The emergence rate of adults in relation to second instar larvae trapped was 43.7%. 35.7% of adults caught after emerging from the soil were males and 64.3 were females. In contrast, yellow traps had recorded 59.1% males and 40.9% females over the same period. The yellow traps were subsequently found to be biased towards male catches when young fruit and/or soft flush was present on the citrus trees. Relative inhibition of female flight activity during times of food abundance is known in other thrips species. During times of food scarcity, the bias in the yellow trap results disappeared. At Letaba Estates, availability of food rather than the direct effects of weather was seen to be the most important factor in governing S. aurantii numbers. Because of the importance of soft flush in the promotion of S. aurantii population increase, it is recommended that more attention should be given to the control of thrips on, as well as conducting surveys for, this food source. As the climate at Letaba is so favourable for citrus thrips, even during winter, it is further recommended that trapping for S. aurantii is carried out throughout the year. Furthermore, males and females should be recorded separately in trapping results as the sex ratio gives an indication of the phenological state of the tree.
- Full Text:
- Date Issued: 1993
- Authors: Gilbert, Martin Jeffray
- Date: 1993
- Subjects: Thrips -- Control -- South Africa Citrus -- Diseases and pests -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5673 , http://hdl.handle.net/10962/d1005358
- Description: The South African Citrus Thrips, Scirtothrips aurantii Faure (Thysanoptera: Thripidae) has been a serious pest of the citrus industry of Southern Africa for over 70 years. It is indigenous to Africa and has no recorded parasitoids and, in most citrus-growing regions, predators are not economically effective. Firstly, in this study, the general ecology of thrips was reviewed along with the recorded history of S. aurantii and its control. Host plant relationships of S. aurantii were then examined and wild hosts were not found to be important in promoting citrus thrips outbreaks in the orchard after flowering. In addition, Scirtothrips dorsalis Hood, which attacks citrus in Asia, was collected for the first time in Africa, but from Castor Oil plant. It is therefore a potential pest of citrus here. Notes on its appearance compared to that of S. aurantii were prepared. Weekly sampling of S. aurantii adults was carried out from June 1984 to May 1990. Population fluctuations were then correlated with phenology of the citrus trees and the direct and indirect effects of weather. Temperature and rainfall were not found to be significantly directly correlated with thrips numbers recorded. However, the indirect effects of rainfall were important in promoting a large winter thrips population in certain years. Relatively high rainfall during March and April compared to that of the previous January and February stimulated atypical flushing of the citrus trees during autumn and the setting of out-of-season fruit. S. aurantii then exploited this unusual food source and high numbers were subsequently recorded in the following winter; as well as in spring. Thus the mild winter climate alone could not suppress thrips numbers at Letaba. Dispersal/Emergence traps, which are used in the U.S.A. for the monitoring of Scirtothrips citri, were evaluated over 24 months, and were effective in recording population peaks of S. aurantii. The emergence rate of adults in relation to second instar larvae trapped was 43.7%. 35.7% of adults caught after emerging from the soil were males and 64.3 were females. In contrast, yellow traps had recorded 59.1% males and 40.9% females over the same period. The yellow traps were subsequently found to be biased towards male catches when young fruit and/or soft flush was present on the citrus trees. Relative inhibition of female flight activity during times of food abundance is known in other thrips species. During times of food scarcity, the bias in the yellow trap results disappeared. At Letaba Estates, availability of food rather than the direct effects of weather was seen to be the most important factor in governing S. aurantii numbers. Because of the importance of soft flush in the promotion of S. aurantii population increase, it is recommended that more attention should be given to the control of thrips on, as well as conducting surveys for, this food source. As the climate at Letaba is so favourable for citrus thrips, even during winter, it is further recommended that trapping for S. aurantii is carried out throughout the year. Furthermore, males and females should be recorded separately in trapping results as the sex ratio gives an indication of the phenological state of the tree.
- Full Text:
- Date Issued: 1993
The effect of hydrostatic carbon dioxide pressure and extracellular ethanol on the performance of the yeast strain Saccharomyces cerevisiae during fermentation
- Authors: Longden, Nicholas Guy
- Date: 1993
- Subjects: Brewing -- Microbiology , Yeast , Fermentation , Saccharomyces cerevisiae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4044 , http://hdl.handle.net/10962/d1004105 , Brewing -- Microbiology , Yeast , Fermentation , Saccharomyces cerevisiae
- Description: The brewing industry constantly experiences problems in trying to maintain the quality of beer produced. Unfavourable conditions during fermentation may alter the performance of the yeast strain Saccharomyces cerevisiae, resulting in a "poor" end-product. It has been established that high concentrations of extracellular ethanol, when added to the fermentation medium inhibit yeast activity. It has been recently suggested that increased carbon dioxide pressure could inactivate the yeast activity adding to further brewing problems. The aim of this study was to investigate the effect of extracellular carbon dioxide pressure and ethanol addition, on yeast performance when added to a fermentation medium, and to establish whether an inhibitory relationship existed between ethanol and carbon dioxide pressure, when combined and added to the fermentation medium. Dissolved C0₂ in the medium, medium pH and substrate utilisation were analysed daily during a fermentation, as were membrane fatty acid composition. These parameters were used to assess the effect of ethanol and carbon dioxide on the yeast performance and consequently the final end-product. Supplementing the medium with extracellular ethanol, even as low as 5%, was shown to inhibit yeast performance during fermentation. This effect was even more marked as the ethanol concentration was increased, with almost total inhibition of yeast activity occuring after the addition of 15% ethanol (v/v). A similar effect was observed when elevated C0₂ pressures were applied to the medium, and although low C0₂ pressures initially induced the synthesis of saturated yeast membrane fatty acids, elevated C0₂ pressures (greater than 1,0 atm.) was shown to follow a similar inhibitory trend, if not as dramatic, as ethanol. A combination of both ethanol and C0₂ pressure showed a further increase in the level of yeast inhibition, although the low C0₂ pressure appeared to initially inhibit the toxicity of ethanol on the yeast. Increasing the levels of the C0₂/ethanol treatment (1,0 atm.), showed a synergistic effect on yeast performance. The results of this study indicate that both extracellular ethanol and carbon dioxide do appear to inhibit yeast performance and affect membrane fatty acid composition of the cells by inhibiting the synthesis of the respective fatty acid. This affect has a significant bearing on the general metabolism of the yeast cell.
- Full Text:
- Date Issued: 1993
- Authors: Longden, Nicholas Guy
- Date: 1993
- Subjects: Brewing -- Microbiology , Yeast , Fermentation , Saccharomyces cerevisiae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4044 , http://hdl.handle.net/10962/d1004105 , Brewing -- Microbiology , Yeast , Fermentation , Saccharomyces cerevisiae
- Description: The brewing industry constantly experiences problems in trying to maintain the quality of beer produced. Unfavourable conditions during fermentation may alter the performance of the yeast strain Saccharomyces cerevisiae, resulting in a "poor" end-product. It has been established that high concentrations of extracellular ethanol, when added to the fermentation medium inhibit yeast activity. It has been recently suggested that increased carbon dioxide pressure could inactivate the yeast activity adding to further brewing problems. The aim of this study was to investigate the effect of extracellular carbon dioxide pressure and ethanol addition, on yeast performance when added to a fermentation medium, and to establish whether an inhibitory relationship existed between ethanol and carbon dioxide pressure, when combined and added to the fermentation medium. Dissolved C0₂ in the medium, medium pH and substrate utilisation were analysed daily during a fermentation, as were membrane fatty acid composition. These parameters were used to assess the effect of ethanol and carbon dioxide on the yeast performance and consequently the final end-product. Supplementing the medium with extracellular ethanol, even as low as 5%, was shown to inhibit yeast performance during fermentation. This effect was even more marked as the ethanol concentration was increased, with almost total inhibition of yeast activity occuring after the addition of 15% ethanol (v/v). A similar effect was observed when elevated C0₂ pressures were applied to the medium, and although low C0₂ pressures initially induced the synthesis of saturated yeast membrane fatty acids, elevated C0₂ pressures (greater than 1,0 atm.) was shown to follow a similar inhibitory trend, if not as dramatic, as ethanol. A combination of both ethanol and C0₂ pressure showed a further increase in the level of yeast inhibition, although the low C0₂ pressure appeared to initially inhibit the toxicity of ethanol on the yeast. Increasing the levels of the C0₂/ethanol treatment (1,0 atm.), showed a synergistic effect on yeast performance. The results of this study indicate that both extracellular ethanol and carbon dioxide do appear to inhibit yeast performance and affect membrane fatty acid composition of the cells by inhibiting the synthesis of the respective fatty acid. This affect has a significant bearing on the general metabolism of the yeast cell.
- Full Text:
- Date Issued: 1993