Determining the relationship between the body image of adolescent girls and their academic achievement, social involvement and sport participation : a pilot study
- Authors: Mostert, Petronella Louisa
- Date: 1995
- Subjects: Body image in adolescence Personality and academic achievement Social interaction in adolescence Self-perception in adolescence Teenage girls -- Psychology Academic achievement
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1492 , http://hdl.handle.net/10962/d1003373
- Description: Ever since the earliest times much emphasis has been placed on the physical appearance of women. Particularly in western cultures idealized images of perfection are constantly promoted and the message that comes across in various media outlets is that a woman ought to have a 'perfect' appearance in order to be competent and desirable. This puts a great deal of stress on women and particularly on adolescent girls who are going through a phase of increased sensitivity about their appearance. The literature suggests that people, and women in particular, are fundamentally affected by the way they view their bodies. The body image furthermore has a strong relationship with the self concept, which affects other areas of a person's life such as her academic achievement and her social 'life. Against this background an attempt was made in this study to determine the relationship between the body image of adolescent girls and their academic achievement, their sport participation and their social involvement. The subjects were 180 girls drawn from two rural secondary schools. The survey involved the completion of two questionnaires, namely an adapted form of the Physical Self Subscale of the Tenessee Self Concept Scale (used to determine a score for body image) and a questionnaire on social involvement and sport participation, which was drawn up by the researcher. Biographic data as well as academic scores were gathered from school records. Data was analysed statistically by means of the BMDP Software Version 1990: programme (Sun Unix). Pearson's chi square tests of independence, as well as a one-way analysis of variance with co-variate were carried out. The results reveal that the body image and academic achievement of this group of girls are not significantly correlated. There are, however, significant correlations between the body image and social involvement of these girls, between their body image and sport participation, as well as between their social involvement and sport participation. iv These findings have important implications for"'e"ducation and consideration is given to addressing these issues in schools.
- Full Text:
- Date Issued: 1995
- Authors: Mostert, Petronella Louisa
- Date: 1995
- Subjects: Body image in adolescence Personality and academic achievement Social interaction in adolescence Self-perception in adolescence Teenage girls -- Psychology Academic achievement
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1492 , http://hdl.handle.net/10962/d1003373
- Description: Ever since the earliest times much emphasis has been placed on the physical appearance of women. Particularly in western cultures idealized images of perfection are constantly promoted and the message that comes across in various media outlets is that a woman ought to have a 'perfect' appearance in order to be competent and desirable. This puts a great deal of stress on women and particularly on adolescent girls who are going through a phase of increased sensitivity about their appearance. The literature suggests that people, and women in particular, are fundamentally affected by the way they view their bodies. The body image furthermore has a strong relationship with the self concept, which affects other areas of a person's life such as her academic achievement and her social 'life. Against this background an attempt was made in this study to determine the relationship between the body image of adolescent girls and their academic achievement, their sport participation and their social involvement. The subjects were 180 girls drawn from two rural secondary schools. The survey involved the completion of two questionnaires, namely an adapted form of the Physical Self Subscale of the Tenessee Self Concept Scale (used to determine a score for body image) and a questionnaire on social involvement and sport participation, which was drawn up by the researcher. Biographic data as well as academic scores were gathered from school records. Data was analysed statistically by means of the BMDP Software Version 1990: programme (Sun Unix). Pearson's chi square tests of independence, as well as a one-way analysis of variance with co-variate were carried out. The results reveal that the body image and academic achievement of this group of girls are not significantly correlated. There are, however, significant correlations between the body image and social involvement of these girls, between their body image and sport participation, as well as between their social involvement and sport participation. iv These findings have important implications for"'e"ducation and consideration is given to addressing these issues in schools.
- Full Text:
- Date Issued: 1995
Dispersal, settlement and recruitment : their influence on the population dynamics of intertidal mussels
- Authors: Phillips, Tracey Elizabeth
- Date: 1995
- Subjects: Perna -- South Africa -- Eastern Cape -- Algoa bay Mytilus galloprovincialis -- South Africa -- Eastern Cape -- Algoa bay Mytilidae -- South Africa -- Eastern Cape -- Algoa bay
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5663 , http://hdl.handle.net/10962/d1005347
- Description: Recruitment of planktonic larvae into sedentary benthic populations regulates the population dynamics of marine invertebrates. The processes controlling recruitment, however, are poorly understood, and recruitment remains largely unpredictable, which complicates management of exploited shellfish resources. The mussels Perna perna, Choromytilus meridionalis and Mytilus galloprovincialis, found on the south coast of southern Africa, have planktonic larvae and sedentary adult stages. This thesis examines dispersal, settlement and early post-settlement growth and mortality, and their effect on recruitment and demography of intertidal mussel populations in the region of Algoa Bay on the south coast of southern Africa. Temporal and spatial variation in the body mass, density and size structure of mussels, the distribution of bivalve larvae on plankton grids in the nearshore zone and the distribution of a recently introduced invasive mussel, Mytilus galloprovincialis, were examined between 1989 and 1992. Furthermore, data on hourly or daily changes in wind strength and direction, air and sea surface temperatures and low and high tide levels in the study region, were obtained. There were 3-4 peaks in spawning (characterised by an abrupt decline in weight) and settlement activity annually. These peaks varied in exact timing, intensity and duration between sites and over time. However, at a site, spawning was followed by settlement 4-8 weeks later, and there was a significant (P < 0.05) direct correlation between spawning intensity prior to the appearance of a new cohort and the cohort density (settlement intensity). The stochastic spatial and temporal variation in breeding activity was superimposed on a more general pattern of a higher intensity of spawning and settlement in Algoa Bay than on the open coast, and a higher settlement intensity on coastal sandstone shores than on dune rock shores. Spawning was more frequent in winter and spring, and the probability of spawning and settlement peaked around the spring and autumn equinox, if temperature and wind conditions were suitable. Larval behaviour had little effect on their dispersal in the well-mixed nearshore region. Larvae were passively dispersed by currents, and their dispersal range and direction depended on prevailing winds and local topography. The sharp decline in density of recruit and adult M. galloprovincialis with increasing distance from the point of introduction, showed that some larvae were carried by wind generated currents over moderately long distances (-100 km). However, since most (76 %) M. galloprovincialis recruited within 4 km of the parent population, it is possible that larvae become trapped in small gullies and crevices around rocky shores, and have a limited dispersal range. This could explain the link between local patterns of spawning and settlement. The distribution and abundance of settlers on the shore was influenced by larval behaviour and the availability of settlement, substrata. Larvae preferred to settle primarily on foliose coralline algae and migrate to the adult mussel bed when they were larger (0.60-7 mm), but larvae also settled directly on adult mussels, possibly because the amount of coralline algae was limited. Both direct and secondary settlement were considered to be important in maintaining mussel populations since the rate of settlement was low(generally < 60 000.m-2). Cohort analyses showed that prior to maturity post-settlement growth (- 30 mm in 10 months) and mortality rates (60-100%) were high, but varied. When settlement intensity was low this variability uncoupled the relationship between spawning and recruitment intensity. Multiple regression analysis showed that together reproductive effort (gamete output), settlement intensity, growth and mortality prior to maturity, accounted for 76 % of the variance in recruitment into mature adult populations. The low settlement rate coupled with the short life span of mussels « 3 years), meant that populations underwent marked spatial and temporal variations in structure and abundance as settlement intensity varied, but there were consistent general differences between mussel populations on dune rock and sandstone shores in Algoa Bay and on the open coast. It was concluded from these results that, spawning intensity and post-settlement growth and mortality, rather than dispersal, regulated recruitment and the structure and abundance of intertidal P. perna and C. meridionalis populations along the south coast of southern Africa. On the basis of these results it is recommended that species with limited dispersal, variable recruitment and high natural mortality, such as P. perna, should be conserved by protecting a small part of the population in reserves, and controlling utilisation outside reserves to minimize disturbance to local brood stocks. Furthermore, since the potential for reseeding adjacent exploited areas is limited, several small reserves placed at regular intervals along the coast would be more effective than a single large reserve.
- Full Text:
- Date Issued: 1995
- Authors: Phillips, Tracey Elizabeth
- Date: 1995
- Subjects: Perna -- South Africa -- Eastern Cape -- Algoa bay Mytilus galloprovincialis -- South Africa -- Eastern Cape -- Algoa bay Mytilidae -- South Africa -- Eastern Cape -- Algoa bay
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5663 , http://hdl.handle.net/10962/d1005347
- Description: Recruitment of planktonic larvae into sedentary benthic populations regulates the population dynamics of marine invertebrates. The processes controlling recruitment, however, are poorly understood, and recruitment remains largely unpredictable, which complicates management of exploited shellfish resources. The mussels Perna perna, Choromytilus meridionalis and Mytilus galloprovincialis, found on the south coast of southern Africa, have planktonic larvae and sedentary adult stages. This thesis examines dispersal, settlement and early post-settlement growth and mortality, and their effect on recruitment and demography of intertidal mussel populations in the region of Algoa Bay on the south coast of southern Africa. Temporal and spatial variation in the body mass, density and size structure of mussels, the distribution of bivalve larvae on plankton grids in the nearshore zone and the distribution of a recently introduced invasive mussel, Mytilus galloprovincialis, were examined between 1989 and 1992. Furthermore, data on hourly or daily changes in wind strength and direction, air and sea surface temperatures and low and high tide levels in the study region, were obtained. There were 3-4 peaks in spawning (characterised by an abrupt decline in weight) and settlement activity annually. These peaks varied in exact timing, intensity and duration between sites and over time. However, at a site, spawning was followed by settlement 4-8 weeks later, and there was a significant (P < 0.05) direct correlation between spawning intensity prior to the appearance of a new cohort and the cohort density (settlement intensity). The stochastic spatial and temporal variation in breeding activity was superimposed on a more general pattern of a higher intensity of spawning and settlement in Algoa Bay than on the open coast, and a higher settlement intensity on coastal sandstone shores than on dune rock shores. Spawning was more frequent in winter and spring, and the probability of spawning and settlement peaked around the spring and autumn equinox, if temperature and wind conditions were suitable. Larval behaviour had little effect on their dispersal in the well-mixed nearshore region. Larvae were passively dispersed by currents, and their dispersal range and direction depended on prevailing winds and local topography. The sharp decline in density of recruit and adult M. galloprovincialis with increasing distance from the point of introduction, showed that some larvae were carried by wind generated currents over moderately long distances (-100 km). However, since most (76 %) M. galloprovincialis recruited within 4 km of the parent population, it is possible that larvae become trapped in small gullies and crevices around rocky shores, and have a limited dispersal range. This could explain the link between local patterns of spawning and settlement. The distribution and abundance of settlers on the shore was influenced by larval behaviour and the availability of settlement, substrata. Larvae preferred to settle primarily on foliose coralline algae and migrate to the adult mussel bed when they were larger (0.60-7 mm), but larvae also settled directly on adult mussels, possibly because the amount of coralline algae was limited. Both direct and secondary settlement were considered to be important in maintaining mussel populations since the rate of settlement was low(generally < 60 000.m-2). Cohort analyses showed that prior to maturity post-settlement growth (- 30 mm in 10 months) and mortality rates (60-100%) were high, but varied. When settlement intensity was low this variability uncoupled the relationship between spawning and recruitment intensity. Multiple regression analysis showed that together reproductive effort (gamete output), settlement intensity, growth and mortality prior to maturity, accounted for 76 % of the variance in recruitment into mature adult populations. The low settlement rate coupled with the short life span of mussels « 3 years), meant that populations underwent marked spatial and temporal variations in structure and abundance as settlement intensity varied, but there were consistent general differences between mussel populations on dune rock and sandstone shores in Algoa Bay and on the open coast. It was concluded from these results that, spawning intensity and post-settlement growth and mortality, rather than dispersal, regulated recruitment and the structure and abundance of intertidal P. perna and C. meridionalis populations along the south coast of southern Africa. On the basis of these results it is recommended that species with limited dispersal, variable recruitment and high natural mortality, such as P. perna, should be conserved by protecting a small part of the population in reserves, and controlling utilisation outside reserves to minimize disturbance to local brood stocks. Furthermore, since the potential for reseeding adjacent exploited areas is limited, several small reserves placed at regular intervals along the coast would be more effective than a single large reserve.
- Full Text:
- Date Issued: 1995
Disturbing the neighbours: an investigation into the relationship between psychopathology and social formations
- Authors: Collins, Anthony
- Date: 1995
- Subjects: Freud, Sigmund, 1856-1939 , Winnicott, D. W. (Donald Woods), 1896-1971 , Social psychiatry , Social psychology , Psychology, Pathological , Frankfurt school of sociology , Political psychology
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2953 , http://hdl.handle.net/10962/d1002462 , Freud, Sigmund, 1856-1939 , Winnicott, D. W. (Donald Woods), 1896-1971 , Social psychiatry , Social psychology , Psychology, Pathological , Frankfurt school of sociology , Political psychology
- Description: This work attempts to confront certain political problems created by the individualistic bias in psychoanalytic thinking, and the resulting failure to adequately theorise the importance of social processes. The thesis traces the origins of intrapsychic thinking to Freud's initial move from the seduction theory to the Oedipal theory. This development is offered as a prototype for the debates between conceptualisations of childhood traumatisation as a social problem of actual abuse occurring within dermed power relations, and theories which locate pathology purely within internal conflicts occurring inside the individual. Several criticisms of this shift are offered, and it s impact on later theory is considered. Here a contrast is offered between the theoretical approaches of Melanie Klein and Donald Winnicott, arguing for the usefulness of Winnicott's emphasis on environmental factors within psychodynamic theory. The impact of these theoretical approaches is illustrated through a critical evaluation of Freud's case study of Judge Schreber. Additional historical material is brought in to show the importance of environmental considerations ignored by Freud, and contrasting psychodynamic readings of the case are offered. As an alternative to purely intrapsychic approaches, a reinterpretation of certain strands of Critical Theory is then presented. Adorno's theory of the Authoritarian Personality and Marcuse' s concept of One-Dimensional Man are extended using Winnicott's formulations concerning psychological development. This leads to an examination of the question of the relationship between social structure and individual consciousness. Post-structuralist accounts of language and the construction of identity are explored. These are then developed drawing on theories of ideology, language and consciousness, integrating these with Winnicott's developmental theory to offer an alternative psychodynamic understanding of the relationship between social process and psychopathology. An attempt is made to reformulate - the notions of consciousness and the unconscious in terms of the possibilities and difficulties of representation within available social symbolic codes. In conclusion the it is argued that psychology needs to integrate critical social theory and contemporary understandings of the social construction of consciousness in order to become a meaning force in positive social transformation.
- Full Text:
- Date Issued: 1995
- Authors: Collins, Anthony
- Date: 1995
- Subjects: Freud, Sigmund, 1856-1939 , Winnicott, D. W. (Donald Woods), 1896-1971 , Social psychiatry , Social psychology , Psychology, Pathological , Frankfurt school of sociology , Political psychology
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2953 , http://hdl.handle.net/10962/d1002462 , Freud, Sigmund, 1856-1939 , Winnicott, D. W. (Donald Woods), 1896-1971 , Social psychiatry , Social psychology , Psychology, Pathological , Frankfurt school of sociology , Political psychology
- Description: This work attempts to confront certain political problems created by the individualistic bias in psychoanalytic thinking, and the resulting failure to adequately theorise the importance of social processes. The thesis traces the origins of intrapsychic thinking to Freud's initial move from the seduction theory to the Oedipal theory. This development is offered as a prototype for the debates between conceptualisations of childhood traumatisation as a social problem of actual abuse occurring within dermed power relations, and theories which locate pathology purely within internal conflicts occurring inside the individual. Several criticisms of this shift are offered, and it s impact on later theory is considered. Here a contrast is offered between the theoretical approaches of Melanie Klein and Donald Winnicott, arguing for the usefulness of Winnicott's emphasis on environmental factors within psychodynamic theory. The impact of these theoretical approaches is illustrated through a critical evaluation of Freud's case study of Judge Schreber. Additional historical material is brought in to show the importance of environmental considerations ignored by Freud, and contrasting psychodynamic readings of the case are offered. As an alternative to purely intrapsychic approaches, a reinterpretation of certain strands of Critical Theory is then presented. Adorno's theory of the Authoritarian Personality and Marcuse' s concept of One-Dimensional Man are extended using Winnicott's formulations concerning psychological development. This leads to an examination of the question of the relationship between social structure and individual consciousness. Post-structuralist accounts of language and the construction of identity are explored. These are then developed drawing on theories of ideology, language and consciousness, integrating these with Winnicott's developmental theory to offer an alternative psychodynamic understanding of the relationship between social process and psychopathology. An attempt is made to reformulate - the notions of consciousness and the unconscious in terms of the possibilities and difficulties of representation within available social symbolic codes. In conclusion the it is argued that psychology needs to integrate critical social theory and contemporary understandings of the social construction of consciousness in order to become a meaning force in positive social transformation.
- Full Text:
- Date Issued: 1995
Environmental education and research in southern Africa: a landscape of shifting priorities
- Authors: Van Rensburg, Eureta Janse
- Date: 1995
- Subjects: Environmental education -- Research -- South Africa Environmental sciences -- Study and teaching (Higher) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1513 , http://hdl.handle.net/10962/d1003395
- Description: What has come to be labelled as 'the environment crisis' has roots in the structures and orientations of modern societies. True to our modernist ways we call on, or offer, education and research, experts and science, to address our socio-ecological concerns. This study set out to identify research priorities in environmental education from within the institutional setting of a university and within the context of environmental and political change in southern Africa and epistemological shifts in educational research traditions. The emergent research design allowed for a progressive clarification of theoretical vantage point: from an instrumental listing of priorities, through the participatory development of a critical and consensual framework for research, to a reflexive description of a landscape of shifting priorities. I collected data over a 3-year period, in inter alia 38 semi-structured interviews, workshops with some 150 participants, focus group discussions, documents and conferences. Participants' professional contexts included environmental education, natural resource management, social and biophysical sciences, development, formal and non-formal education, funding agencies, academic and non-academic settings. My engagement with the emerging discourses revealed patterns and inconsistencies in participants' views on research, environmental education, change and research priorities. I identified three orientations - Research for Management to Restore Order to Nature and Society, Research to Resolve Practitioners' and Communities' Problems, and Research for Radical Reconstruction - in the emerging landscape. These orientations were accompanied by change models and themes (discourses of difference and 'othering', instrumental views of education and research and accumulative knowledge, a conceptual theory-practice gap) which limited their potential for transformation towards sustainable living. They presented solutions cut from the same modernist cloth as the environment crisis. An emerging Reflexive perspective in and on environmental education research showed potential as a transitionary orientation outside modernist assumptions. I outline research priorities from this perspective. Reflexivity reveals the myths of expert-driven, instrumental and institutionalised research separated from environmental education and based upon rationalistic interpretations of science. It opens up possibilities for transformative knowledge emerging from 're-search' based versions of education as a process of, rather than a means to, social change.
- Full Text:
- Date Issued: 1995
- Authors: Van Rensburg, Eureta Janse
- Date: 1995
- Subjects: Environmental education -- Research -- South Africa Environmental sciences -- Study and teaching (Higher) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1513 , http://hdl.handle.net/10962/d1003395
- Description: What has come to be labelled as 'the environment crisis' has roots in the structures and orientations of modern societies. True to our modernist ways we call on, or offer, education and research, experts and science, to address our socio-ecological concerns. This study set out to identify research priorities in environmental education from within the institutional setting of a university and within the context of environmental and political change in southern Africa and epistemological shifts in educational research traditions. The emergent research design allowed for a progressive clarification of theoretical vantage point: from an instrumental listing of priorities, through the participatory development of a critical and consensual framework for research, to a reflexive description of a landscape of shifting priorities. I collected data over a 3-year period, in inter alia 38 semi-structured interviews, workshops with some 150 participants, focus group discussions, documents and conferences. Participants' professional contexts included environmental education, natural resource management, social and biophysical sciences, development, formal and non-formal education, funding agencies, academic and non-academic settings. My engagement with the emerging discourses revealed patterns and inconsistencies in participants' views on research, environmental education, change and research priorities. I identified three orientations - Research for Management to Restore Order to Nature and Society, Research to Resolve Practitioners' and Communities' Problems, and Research for Radical Reconstruction - in the emerging landscape. These orientations were accompanied by change models and themes (discourses of difference and 'othering', instrumental views of education and research and accumulative knowledge, a conceptual theory-practice gap) which limited their potential for transformation towards sustainable living. They presented solutions cut from the same modernist cloth as the environment crisis. An emerging Reflexive perspective in and on environmental education research showed potential as a transitionary orientation outside modernist assumptions. I outline research priorities from this perspective. Reflexivity reveals the myths of expert-driven, instrumental and institutionalised research separated from environmental education and based upon rationalistic interpretations of science. It opens up possibilities for transformative knowledge emerging from 're-search' based versions of education as a process of, rather than a means to, social change.
- Full Text:
- Date Issued: 1995
Equal opportunities for women
- Federation of Unions of South Africa
- Authors: Federation of Unions of South Africa
- Date: 1995
- Subjects: FEDUSA
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/110109 , vital:33224
- Description: Over the last thirty years, there has been considerable evolution in the thinking about gender equality issues and the actions needed to achieve real changes in the position of women vis-a-vis men. Prior to the 1970s, women were defined mainly in terms of their conventional reproductive roles, and efforts to improve women's welfare focussed on such programmes as literacy courses, home economics, child care and family planning. Though no doubt valuable, such welfare and family-oriented programmes had the effect of reinforcing women's traditional role in the family. Since the 1970s, there has been a shift to the division of labour based on sex, and the impact of development and modernization strategies on women. It is important to understand that improvements in women's status require analysis of the relations between men and women, as well as the concurrence and cooperation of men. As illustrated in the Beijing document: "Achieving gender equality and empowerment of women requires redressing inequalities between women and men and girls and boys and ensuring their equal rights, responsibilities, opportunities and possibilities. Gender equality implies that women's as well as men's needs, interests, concerns, experiences and priorities are an integral dimension of the design, implementation, national monitoring and follow-up and evaluation, including at the international level, of all actions in all areas."
- Full Text:
- Date Issued: 1995
- Authors: Federation of Unions of South Africa
- Date: 1995
- Subjects: FEDUSA
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/110109 , vital:33224
- Description: Over the last thirty years, there has been considerable evolution in the thinking about gender equality issues and the actions needed to achieve real changes in the position of women vis-a-vis men. Prior to the 1970s, women were defined mainly in terms of their conventional reproductive roles, and efforts to improve women's welfare focussed on such programmes as literacy courses, home economics, child care and family planning. Though no doubt valuable, such welfare and family-oriented programmes had the effect of reinforcing women's traditional role in the family. Since the 1970s, there has been a shift to the division of labour based on sex, and the impact of development and modernization strategies on women. It is important to understand that improvements in women's status require analysis of the relations between men and women, as well as the concurrence and cooperation of men. As illustrated in the Beijing document: "Achieving gender equality and empowerment of women requires redressing inequalities between women and men and girls and boys and ensuring their equal rights, responsibilities, opportunities and possibilities. Gender equality implies that women's as well as men's needs, interests, concerns, experiences and priorities are an integral dimension of the design, implementation, national monitoring and follow-up and evaluation, including at the international level, of all actions in all areas."
- Full Text:
- Date Issued: 1995
Equilibrium and kinetic studies of the reaction between pyridine and cobalt (II) phthalocyanine in DMSO
- Authors: Nyokong, Tebello
- Date: 1995
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293380 , vital:57080 , xlink:href="https://doi.org/10.1016/0277-5387(95)00090-F"
- Description: Kinetics and equilibria for the reaction between pyridine and cobalt(II) phthalocyanine [CoPc] (H2Pc = phthalocyanine) in dimethyl sulphoxide (DMSO) were studied at 25°C. The complex, CoPc(py)2, is formed in two consecutive steps. The formation of the mono-substituted CoPc(py)(DMSO) occurs first with a pseudo-first-order rate constant of k1f = 7.7 ± 0.3 × 10−3 dm3 mol−1 s−1. The final disubstituted CoPc(py)2 complex is formed with k2f= 1.1 ± 0.1 × 10−4dm3mol−1−1. The equilibrium constants were found to be K1 = 160 ± 20dm3 mol−1 and K2 = 15 ± 3 dm3mol−1 for the formation of CoPc(py)(DMSO) and CoPc(py)2, respectively.
- Full Text:
- Date Issued: 1995
- Authors: Nyokong, Tebello
- Date: 1995
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293380 , vital:57080 , xlink:href="https://doi.org/10.1016/0277-5387(95)00090-F"
- Description: Kinetics and equilibria for the reaction between pyridine and cobalt(II) phthalocyanine [CoPc] (H2Pc = phthalocyanine) in dimethyl sulphoxide (DMSO) were studied at 25°C. The complex, CoPc(py)2, is formed in two consecutive steps. The formation of the mono-substituted CoPc(py)(DMSO) occurs first with a pseudo-first-order rate constant of k1f = 7.7 ± 0.3 × 10−3 dm3 mol−1 s−1. The final disubstituted CoPc(py)2 complex is formed with k2f= 1.1 ± 0.1 × 10−4dm3mol−1−1. The equilibrium constants were found to be K1 = 160 ± 20dm3 mol−1 and K2 = 15 ± 3 dm3mol−1 for the formation of CoPc(py)(DMSO) and CoPc(py)2, respectively.
- Full Text:
- Date Issued: 1995
Evaluation of Gratiana spadicea (Klug, 1829) and Metriona elatior (Klug, 1829) (Chrysomelidae: Cassidinae) for the biological control of sticky nightshade Solanum sisymbriifolium Lamarck (Solanaceae) in South Africa
- Authors: Hill, Martin Patrick
- Date: 1995
- Subjects: Solanaceae Solanaceae -- Biological control Chrysomelidae Chrysomelidae -- Host plants Cassida
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5688 , http://hdl.handle.net/10962/d1005374 , https://orcid.org/0000-0003-0579-5298
- Description: Solanum sisymbriifolium (sticky nightshade) is a shrubby weed of South American origin that was introduced to South Africa at the turn of the century. Despite being indicative of disturbed habitats, the weed was found to be invasive in conservation, agricultural recreational and suburban areas; this, coupled with the failure of both chemical and mechanical control attempts suggested that the weed was a good candidate for biological control. A biological control programme which followed a standard protocol was initiated. Observations suggested that S. sisymbriifolium dispersed primarily by seeds. Plants produced large quantities of fleshy fruit, favoured by frugivorous birds, which facilitated the rapid spread of the weed into new habitats. The seeds germinated quickly, especially in disturbed soil, often below the parent plant where they dropped from burst fruit, and along fences where birds roost. The pre-introductory survey of the weed revealed that S. sisymbriifolium was attacked by a relatively small number of, mainly polyphagous, herbivorous insects. These were localised and sporadic in incidence and inflicted very little observable damage. The herbivore fauna of S. sisymbriifolium was depauperate even in relation to two other exotic weeds, S. elaeaglllfolium and S. mauritianum, in South Africa. The paucity of native herbivores on S. sisymbriifoliwn was ascribed to a combination of the weed's taxonomic distinctness from South African Solanum species, and the dense covering of glandular trichomes on its leaves. Although it was shown that the exudate produced by these glandular trichomes of S. sisymbriifolium seriously impeded the movement and feeding of native herbivores, there was not enough evidence to suggest that the glandular trichomes, alone could have been responsible the lack of herbivores on the weed. Two leaf-feeding Cassidinae Gratiana spadicea and MetJ-iona elatior were screened as agents for the biological control of S. sisymbrilfolium. Favourable biological characteristics for both species included a high rate of increase, long-lived adults, many generations per year, and a high per capita feeding rate. Host range was investigated in larval survival tests and adult choice tests. The larvae of both species were reared through to the adult stage on several of the native Solanum species tested, and also on eggplant (S. melongena). However, the survival of G. spadicea on the majority of these species was very low, suggesting that the beetles would be unlikely to attack them in the field. This was supported by the adult choice tests, where G. spadicea females displayed, a strong oviposition preference for their natural host. In contrast, M. elatior larvae survived well on non-host plants, and the females selected several non-host species, including eggplant for oviposition. It was argued that the conflict of interests involving eggplant was overrated because eggplant is subjected to a stringent insecticide spray regime. Based on this evidence, permission for release was granted for G. spadicea. The impact of native parasitoid host range extensions to weed biological control agents in South Africa was investigated. Native parasitoids were recorded from nearly half of the agent species that had established on their target weed. The level of concealment and taxon influenced susceptibility of the agents to parasitoid attack Poorly concealed endophagous agents were most susceptible to attack, while exposed feeders were fairly free from attack. However, native parasitoids were reported not to strongly influence weed biological control agent populations and it was concluded that no agent should be rejected based only on its susceptibility to native parasitoid attack. Finally, several predictions are made as to the potential success of G. spadicea on S. sisymbriifolium and some of the challenges facing the biological control of weeds are discussed.
- Full Text:
- Date Issued: 1995
- Authors: Hill, Martin Patrick
- Date: 1995
- Subjects: Solanaceae Solanaceae -- Biological control Chrysomelidae Chrysomelidae -- Host plants Cassida
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5688 , http://hdl.handle.net/10962/d1005374 , https://orcid.org/0000-0003-0579-5298
- Description: Solanum sisymbriifolium (sticky nightshade) is a shrubby weed of South American origin that was introduced to South Africa at the turn of the century. Despite being indicative of disturbed habitats, the weed was found to be invasive in conservation, agricultural recreational and suburban areas; this, coupled with the failure of both chemical and mechanical control attempts suggested that the weed was a good candidate for biological control. A biological control programme which followed a standard protocol was initiated. Observations suggested that S. sisymbriifolium dispersed primarily by seeds. Plants produced large quantities of fleshy fruit, favoured by frugivorous birds, which facilitated the rapid spread of the weed into new habitats. The seeds germinated quickly, especially in disturbed soil, often below the parent plant where they dropped from burst fruit, and along fences where birds roost. The pre-introductory survey of the weed revealed that S. sisymbriifolium was attacked by a relatively small number of, mainly polyphagous, herbivorous insects. These were localised and sporadic in incidence and inflicted very little observable damage. The herbivore fauna of S. sisymbriifolium was depauperate even in relation to two other exotic weeds, S. elaeaglllfolium and S. mauritianum, in South Africa. The paucity of native herbivores on S. sisymbriifoliwn was ascribed to a combination of the weed's taxonomic distinctness from South African Solanum species, and the dense covering of glandular trichomes on its leaves. Although it was shown that the exudate produced by these glandular trichomes of S. sisymbriifolium seriously impeded the movement and feeding of native herbivores, there was not enough evidence to suggest that the glandular trichomes, alone could have been responsible the lack of herbivores on the weed. Two leaf-feeding Cassidinae Gratiana spadicea and MetJ-iona elatior were screened as agents for the biological control of S. sisymbrilfolium. Favourable biological characteristics for both species included a high rate of increase, long-lived adults, many generations per year, and a high per capita feeding rate. Host range was investigated in larval survival tests and adult choice tests. The larvae of both species were reared through to the adult stage on several of the native Solanum species tested, and also on eggplant (S. melongena). However, the survival of G. spadicea on the majority of these species was very low, suggesting that the beetles would be unlikely to attack them in the field. This was supported by the adult choice tests, where G. spadicea females displayed, a strong oviposition preference for their natural host. In contrast, M. elatior larvae survived well on non-host plants, and the females selected several non-host species, including eggplant for oviposition. It was argued that the conflict of interests involving eggplant was overrated because eggplant is subjected to a stringent insecticide spray regime. Based on this evidence, permission for release was granted for G. spadicea. The impact of native parasitoid host range extensions to weed biological control agents in South Africa was investigated. Native parasitoids were recorded from nearly half of the agent species that had established on their target weed. The level of concealment and taxon influenced susceptibility of the agents to parasitoid attack Poorly concealed endophagous agents were most susceptible to attack, while exposed feeders were fairly free from attack. However, native parasitoids were reported not to strongly influence weed biological control agent populations and it was concluded that no agent should be rejected based only on its susceptibility to native parasitoid attack. Finally, several predictions are made as to the potential success of G. spadicea on S. sisymbriifolium and some of the challenges facing the biological control of weeds are discussed.
- Full Text:
- Date Issued: 1995
Fish community structure in three temporarily open/closed estuaries on the Natal coast
- Harrison, Trevor D, Whitfield, Alan K
- Authors: Harrison, Trevor D , Whitfield, Alan K
- Date: 1995
- Language: English
- Type: Text
- Identifier: vital:15026 , http://hdl.handle.net/10962/d1019890 , ISSN 0073-4381 , Ichthyological Bulletin J.L.B. Smith Institute of Ichthyology; No. 64
- Description: The fishes of three small Natal estuaries, the Mhlanga, Damba and Zotsha were sampled over a period of two years. A total of 68 fish taxa representing 24 families, 39 genera and 55 species were captured during this study. Forty seven fish taxa were recorded in the Mhlanga estuary of which Gilchristella aestuaria, Oreochromis mossambicus, Valamugil cunnesius, Valamugil sp. and juvenile mugilids numerically dominated. In terms of biomass, O. mossambicus, V. cunnesius, Liza alata, Myxus capensis and Mugil cephalus dominated the ichthyofauna of the Mhlanga system. In the Damba estuary, 24 fish taxa were recorded, the most abundant being Glossogobius callidus,M. capensis and 0. mossambicus. M. capensis, M. cephalus, O. mossambicus and G. callidus dominated the fish biomass captured in the Damba system. A total of 56 fish taxa were recorded in the Zotsha estuary during this study, with the ichthyofauna numerically dominated by juvenile mugilids, G. aestuaria, O. mossambicus, Rhabdosargus holubi, Terapon jarbua, Ambassis productus and G. callidus. The species which dominated the fish biomass in the Zotsha system were 0. mossambicus L. alata, Valamugil robustus, V. buchanani, M. capensis, M. cephalus and V. cunnesius. Classifying the species according to whether they were resident estuarine, freshwater, estuarine-dependent marine or marine species revealed that the first three groups were all well represented in the systems. Oreochromis mossambicus was the dominant freshwater species in all three estuaries. Gilchristella aestuaria and Glossogobius callidus were the principal estuarine species in the Mhlanga and the Damba respectively, with G. aestuaria, A. productus and G. callidus being the dominant estuarine species captured in the Zotsha. The principal estuarine-dependent marine fishes captured in the Mhlanga were V. cunnesius, Valamugil sp., juvenile mugilids, M. capensis, M. cephalus and L. alata. In the Damba, M. capensis and M. cephalus were the dominant estuarine-dependent marine species and in the Zotsha juvenile mugilids, R. holubi, T. jarbua, M. capensis, V. cunnesius, V. robustus, M. cephalus, L. alata and V. buchanani were the principal estuarine-dependent marine species. The results of this study indicate that the estuaries are dominated at different periods by different assemblages of fishes. This is linked to the spawning and migration patterns of the various species as well as the hydrological regime of each estuary. During the winter these systems are normally closed with relatively deep waters and high food resource and habitat availability. Freshwater and estuarine species mainly inhabit the upper reaches of the systems while estuarine-dependent marine species, which dominate the fish community, mainly occupy the middle and lower reaches. When these estuaries open with the onset of the spring/summer rains, adult and sub-adult estuarine-dependent marine species emigrate to the marine environment and juveniles begin recruiting into the systems. Spring is also the peak breeding period of resident estuarine and freshwater species, resulting in an increase in the contribution of these fishes to the overall ichthyofauna during this period. When closed estuaries open the water level falls and this results in the fishes concentrating in the lower reaches of the system where moderate water depths are present, thus further contributing to an increase in the proportion of freshwater and estuarine species in this region. The breaching of closed estuaries also results in a reduction in food resources and habitat availability. Competition and possible increased vulnerability to avian predation (due to the shallow nature of the systems), may contribute to a decrease in the proportion of estuarine and freshwater species in summer. The prolonged recruitment of Of-juveniles of estuarine-dependent marine species results in an increase in the proportion of these fishes present in the estuaries during summer. In autumn, the systems normally close, water levels rise and available food resources and habitat increase. This allows the redistribution of freshwater and estuarine species upstream, leaving estuarine-dependent marine species to dominate the middle and lower reaches. Although temporarily open/closed estuaries along the Natal coast may not be as diverse as permanently open estuaries in terms of their ichthyofauna, their importance must not be underestimated, since by providing a series of sheltered habitats along the coast they may contribute significantly to the viability of estuarine-dependent marine fish stocks. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1995
- Authors: Harrison, Trevor D , Whitfield, Alan K
- Date: 1995
- Language: English
- Type: Text
- Identifier: vital:15026 , http://hdl.handle.net/10962/d1019890 , ISSN 0073-4381 , Ichthyological Bulletin J.L.B. Smith Institute of Ichthyology; No. 64
- Description: The fishes of three small Natal estuaries, the Mhlanga, Damba and Zotsha were sampled over a period of two years. A total of 68 fish taxa representing 24 families, 39 genera and 55 species were captured during this study. Forty seven fish taxa were recorded in the Mhlanga estuary of which Gilchristella aestuaria, Oreochromis mossambicus, Valamugil cunnesius, Valamugil sp. and juvenile mugilids numerically dominated. In terms of biomass, O. mossambicus, V. cunnesius, Liza alata, Myxus capensis and Mugil cephalus dominated the ichthyofauna of the Mhlanga system. In the Damba estuary, 24 fish taxa were recorded, the most abundant being Glossogobius callidus,M. capensis and 0. mossambicus. M. capensis, M. cephalus, O. mossambicus and G. callidus dominated the fish biomass captured in the Damba system. A total of 56 fish taxa were recorded in the Zotsha estuary during this study, with the ichthyofauna numerically dominated by juvenile mugilids, G. aestuaria, O. mossambicus, Rhabdosargus holubi, Terapon jarbua, Ambassis productus and G. callidus. The species which dominated the fish biomass in the Zotsha system were 0. mossambicus L. alata, Valamugil robustus, V. buchanani, M. capensis, M. cephalus and V. cunnesius. Classifying the species according to whether they were resident estuarine, freshwater, estuarine-dependent marine or marine species revealed that the first three groups were all well represented in the systems. Oreochromis mossambicus was the dominant freshwater species in all three estuaries. Gilchristella aestuaria and Glossogobius callidus were the principal estuarine species in the Mhlanga and the Damba respectively, with G. aestuaria, A. productus and G. callidus being the dominant estuarine species captured in the Zotsha. The principal estuarine-dependent marine fishes captured in the Mhlanga were V. cunnesius, Valamugil sp., juvenile mugilids, M. capensis, M. cephalus and L. alata. In the Damba, M. capensis and M. cephalus were the dominant estuarine-dependent marine species and in the Zotsha juvenile mugilids, R. holubi, T. jarbua, M. capensis, V. cunnesius, V. robustus, M. cephalus, L. alata and V. buchanani were the principal estuarine-dependent marine species. The results of this study indicate that the estuaries are dominated at different periods by different assemblages of fishes. This is linked to the spawning and migration patterns of the various species as well as the hydrological regime of each estuary. During the winter these systems are normally closed with relatively deep waters and high food resource and habitat availability. Freshwater and estuarine species mainly inhabit the upper reaches of the systems while estuarine-dependent marine species, which dominate the fish community, mainly occupy the middle and lower reaches. When these estuaries open with the onset of the spring/summer rains, adult and sub-adult estuarine-dependent marine species emigrate to the marine environment and juveniles begin recruiting into the systems. Spring is also the peak breeding period of resident estuarine and freshwater species, resulting in an increase in the contribution of these fishes to the overall ichthyofauna during this period. When closed estuaries open the water level falls and this results in the fishes concentrating in the lower reaches of the system where moderate water depths are present, thus further contributing to an increase in the proportion of freshwater and estuarine species in this region. The breaching of closed estuaries also results in a reduction in food resources and habitat availability. Competition and possible increased vulnerability to avian predation (due to the shallow nature of the systems), may contribute to a decrease in the proportion of estuarine and freshwater species in summer. The prolonged recruitment of Of-juveniles of estuarine-dependent marine species results in an increase in the proportion of these fishes present in the estuaries during summer. In autumn, the systems normally close, water levels rise and available food resources and habitat increase. This allows the redistribution of freshwater and estuarine species upstream, leaving estuarine-dependent marine species to dominate the middle and lower reaches. Although temporarily open/closed estuaries along the Natal coast may not be as diverse as permanently open estuaries in terms of their ichthyofauna, their importance must not be underestimated, since by providing a series of sheltered habitats along the coast they may contribute significantly to the viability of estuarine-dependent marine fish stocks. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1995
Fishes of the Tristan da Cunha Group and Gough Island, South Atlantic Ocean
- Andrew, T G, Hecht, Thomas, Heemstra, Phillip C, Lutjeharms, J R E
- Authors: Andrew, T G , Hecht, Thomas , Heemstra, Phillip C , Lutjeharms, J R E
- Date: 1995
- Language: English
- Type: Text
- Identifier: vital:15025 , http://hdl.handle.net/10962/d1019889 , ISSN 0073-4381 , Ichthyological Bulletin J.L.B. Smith Institute of Ichthyology; No. 63
- Description: Recent collections of fishes from the South Atlantic islands of the Tristan da Cunha Group (Tristan, Inaccessible and Nightingale) and Gough Island have produced 25 new records. Fifty one species are known to occur in the near-shore waters of the islands (46 of these are documented by specimens and another 5 species are probable). A diagnosis, synonymy and in most cases, an illustration, are provided for each species. For certain species, brief notes on biology, relative abundance and seasonal distribution are included. The neritic ichthyofauna of the Subtropical Convergence (STC) region is characterized, and the importance of this frontal zone as a barrier to dispersal of species in the Southern Ocean is evaluated. Analysis of the zoogeographic affinities of the Tristan/Gough fish fauna resulted in a redefinition of the West Wind Drift Islands Province (WWDI), comprising the Tristan Group and Gough in the South Atlantic and St. Paul and Amsterdam Islands in the southern Indian Ocean. Verna Seamount (west of Cape Town) and Walters Shoal (south of Madagascar) are excluded from the WWDI Province, as the affinities of their poorly-known fish faunas appear to be more with South Africa and the tropical Indian Ocean respectively. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1995
- Authors: Andrew, T G , Hecht, Thomas , Heemstra, Phillip C , Lutjeharms, J R E
- Date: 1995
- Language: English
- Type: Text
- Identifier: vital:15025 , http://hdl.handle.net/10962/d1019889 , ISSN 0073-4381 , Ichthyological Bulletin J.L.B. Smith Institute of Ichthyology; No. 63
- Description: Recent collections of fishes from the South Atlantic islands of the Tristan da Cunha Group (Tristan, Inaccessible and Nightingale) and Gough Island have produced 25 new records. Fifty one species are known to occur in the near-shore waters of the islands (46 of these are documented by specimens and another 5 species are probable). A diagnosis, synonymy and in most cases, an illustration, are provided for each species. For certain species, brief notes on biology, relative abundance and seasonal distribution are included. The neritic ichthyofauna of the Subtropical Convergence (STC) region is characterized, and the importance of this frontal zone as a barrier to dispersal of species in the Southern Ocean is evaluated. Analysis of the zoogeographic affinities of the Tristan/Gough fish fauna resulted in a redefinition of the West Wind Drift Islands Province (WWDI), comprising the Tristan Group and Gough in the South Atlantic and St. Paul and Amsterdam Islands in the southern Indian Ocean. Verna Seamount (west of Cape Town) and Walters Shoal (south of Madagascar) are excluded from the WWDI Province, as the affinities of their poorly-known fish faunas appear to be more with South Africa and the tropical Indian Ocean respectively. , Rhodes University Libraries (Digitisation)
- Full Text:
- Date Issued: 1995
Focus on the labour realtions bill and Nedlac
- COSATU
- Authors: COSATU
- Date: Feb 1995
- Subjects: COSATU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/136452 , vital:37380
- Description: The year has hardly begun but there are already exciting developments for workers. On 2 February, the Minister of Labour, Tito Mboweni, unveiled a new draft Labour Relations Bill and on 18 February President Nelson Mandela launched the new National Economic, Development and Labour Council, called NEDLAC. The draft Labour Relations Act is a culmination of struggles by workers over the years against apartheid’s labour dispensation. Many of our demands from the Workers Charter and Platform of Worker Rights are included in the proposed law. The strike wave by Pick ’n Pay workers and others last year sent a clear message to the new government: “Our labour law is out of date and inappropriate for a democratic country.” In August 1994, the Minister of Labour appointed a team of lawyers to draft a new law.
- Full Text:
- Date Issued: Feb 1995
- Authors: COSATU
- Date: Feb 1995
- Subjects: COSATU
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/136452 , vital:37380
- Description: The year has hardly begun but there are already exciting developments for workers. On 2 February, the Minister of Labour, Tito Mboweni, unveiled a new draft Labour Relations Bill and on 18 February President Nelson Mandela launched the new National Economic, Development and Labour Council, called NEDLAC. The draft Labour Relations Act is a culmination of struggles by workers over the years against apartheid’s labour dispensation. Many of our demands from the Workers Charter and Platform of Worker Rights are included in the proposed law. The strike wave by Pick ’n Pay workers and others last year sent a clear message to the new government: “Our labour law is out of date and inappropriate for a democratic country.” In August 1994, the Minister of Labour appointed a team of lawyers to draft a new law.
- Full Text:
- Date Issued: Feb 1995
Foreign labour migration to South Africa after apartheid: continuity or change?
- Authors: Myataza, Lutando Samuel
- Date: 1995
- Subjects: Foreign workers -- South Africa , Black people -- Employment -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2813 , http://hdl.handle.net/10962/d1003023 , Foreign workers -- South Africa , Black people -- Employment -- South Africa
- Description: Migrant labour constitutes one of the perennial problems of the political economy of the Southern African region. The movement of people between their home countries and the gold mines in South Africa is over a hundred years old. In this sense, labour migrancy predates apartheid, and is now threatening to outlive it. Migrants working in South Africa make up a sizable proportion of the total wage earning population of the neighbouring countries (Botswana, Lesotho, Swaziland, Mozambique and Malawi). Their entrenched dependence on migrant-based revenue has made them vulnerable to fluctuations in labour flows to the gold mines (Davies, 1992) The developments since the first quarter of 1988 have altered the terms of debate on migrant labour. With the independence of Namibia and the establishment of a new government in South Africa, to name but a few, the pattern of future regional cooperation has become a central issue. Likewise, the debate about labour migrancy has entered a new phase. Given the current political changes, and yet to take place, this study constitutes a modest attempt to contribute to the debate by examining the prospects of restructuring of labour migrancy to the gold mining industry. The central aim of this undertaking will be to establish what the future holds for the foreign component of the labour force. The focus here will be on the emerging debates in this area, policy pronouncements by major stakeholders, the Chamber of Mines and the new Government of National Unity. However, an informed forecast on the future of labour migrancy is possible only if we establish the conditions that created it in the first place; how it has been constructed overtime; and the successive moments of transformation in the system. In this regard, this study will locate the origins and development of labour migration in its proper historical context ~ before drawing conclusions about the future of the system. In this scholarly pursuit one does not pretend to break a new ground but rather to re-interpret the current literature on migration and establish whether the current pattern of labour migration will change. The research will be based mainly on secondary materials, drawing extensively on published materials, journals and articles.
- Full Text:
- Date Issued: 1995
- Authors: Myataza, Lutando Samuel
- Date: 1995
- Subjects: Foreign workers -- South Africa , Black people -- Employment -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2813 , http://hdl.handle.net/10962/d1003023 , Foreign workers -- South Africa , Black people -- Employment -- South Africa
- Description: Migrant labour constitutes one of the perennial problems of the political economy of the Southern African region. The movement of people between their home countries and the gold mines in South Africa is over a hundred years old. In this sense, labour migrancy predates apartheid, and is now threatening to outlive it. Migrants working in South Africa make up a sizable proportion of the total wage earning population of the neighbouring countries (Botswana, Lesotho, Swaziland, Mozambique and Malawi). Their entrenched dependence on migrant-based revenue has made them vulnerable to fluctuations in labour flows to the gold mines (Davies, 1992) The developments since the first quarter of 1988 have altered the terms of debate on migrant labour. With the independence of Namibia and the establishment of a new government in South Africa, to name but a few, the pattern of future regional cooperation has become a central issue. Likewise, the debate about labour migrancy has entered a new phase. Given the current political changes, and yet to take place, this study constitutes a modest attempt to contribute to the debate by examining the prospects of restructuring of labour migrancy to the gold mining industry. The central aim of this undertaking will be to establish what the future holds for the foreign component of the labour force. The focus here will be on the emerging debates in this area, policy pronouncements by major stakeholders, the Chamber of Mines and the new Government of National Unity. However, an informed forecast on the future of labour migrancy is possible only if we establish the conditions that created it in the first place; how it has been constructed overtime; and the successive moments of transformation in the system. In this regard, this study will locate the origins and development of labour migration in its proper historical context ~ before drawing conclusions about the future of the system. In this scholarly pursuit one does not pretend to break a new ground but rather to re-interpret the current literature on migration and establish whether the current pattern of labour migration will change. The research will be based mainly on secondary materials, drawing extensively on published materials, journals and articles.
- Full Text:
- Date Issued: 1995
Formulating the African National Congress' foreign investment policy in the transition to a post-apartheid South Africa: problems, pressures and constraints
- Authors: Carim, Xavier
- Date: 1995
- Subjects: Investments, Foreign -- South Africa , Political stability -- South Africa , African National Congress -- Foreign economic relations , South Africa -- Foreign economic relations , South Africa -- Economic policy , South Africa -- Economic conditions -- 1991-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2764 , http://hdl.handle.net/10962/d1002974 , Investments, Foreign -- South Africa , Political stability -- South Africa , African National Congress -- Foreign economic relations , South Africa -- Foreign economic relations , South Africa -- Economic policy , South Africa -- Economic conditions -- 1991-
- Description: This study examines the wide-ranging and critical factors which have impacted on the African National Congress' (ANC) emerging foreign investment policy. It identifies and analyses the matrix of political and socio-economic factors which have combined at global and national levels to shape ANC policy perspectives towards foreign direct investment (FDI). In so doing, the study adopts an eclectic theoretical and methodological approach. It draws on various theoretical traditions to propose a framework that is heuristic and contingent, rather than axiomatic. With regard to foreign investment, in particular, it recommends a theoretical pluralism emphasising 'engagement' through praxis and sound political (state) action. The study argues that the ANC has reconsidered many of its basic assumptions on the nature of the post-apartheid economy and discusses the reasons for those shifts. The reasons include, in particular, global political and economic trends and the balance of forces in South Africa. These have combined to ensure the ANC's broad acceptance of an 'open-door policy' towards FDI so long as it occurs on terms not inconsistent with national objectives. The emerging policy sees the state playing an active role in encouraging and guiding FDI to specific areas and sectors supportive of broad-based development. Foreign investors will be encouraged to form joint ventures with emerging black businesses and agree to foster training, skills development and affirmative action. Harnessing the benefits of FDI will be important for the success of wider strategies designed to place the economy on a firmer, more sustainable growth path.
- Full Text:
- Date Issued: 1995
- Authors: Carim, Xavier
- Date: 1995
- Subjects: Investments, Foreign -- South Africa , Political stability -- South Africa , African National Congress -- Foreign economic relations , South Africa -- Foreign economic relations , South Africa -- Economic policy , South Africa -- Economic conditions -- 1991-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2764 , http://hdl.handle.net/10962/d1002974 , Investments, Foreign -- South Africa , Political stability -- South Africa , African National Congress -- Foreign economic relations , South Africa -- Foreign economic relations , South Africa -- Economic policy , South Africa -- Economic conditions -- 1991-
- Description: This study examines the wide-ranging and critical factors which have impacted on the African National Congress' (ANC) emerging foreign investment policy. It identifies and analyses the matrix of political and socio-economic factors which have combined at global and national levels to shape ANC policy perspectives towards foreign direct investment (FDI). In so doing, the study adopts an eclectic theoretical and methodological approach. It draws on various theoretical traditions to propose a framework that is heuristic and contingent, rather than axiomatic. With regard to foreign investment, in particular, it recommends a theoretical pluralism emphasising 'engagement' through praxis and sound political (state) action. The study argues that the ANC has reconsidered many of its basic assumptions on the nature of the post-apartheid economy and discusses the reasons for those shifts. The reasons include, in particular, global political and economic trends and the balance of forces in South Africa. These have combined to ensure the ANC's broad acceptance of an 'open-door policy' towards FDI so long as it occurs on terms not inconsistent with national objectives. The emerging policy sees the state playing an active role in encouraging and guiding FDI to specific areas and sectors supportive of broad-based development. Foreign investors will be encouraged to form joint ventures with emerging black businesses and agree to foster training, skills development and affirmative action. Harnessing the benefits of FDI will be important for the success of wider strategies designed to place the economy on a firmer, more sustainable growth path.
- Full Text:
- Date Issued: 1995
Function of a cloned polyphenolase in organic synthesis
- Authors: Naidoo, Michael Joseph
- Date: 1995
- Subjects: Polyphenols , Catechol , Streptomacyes , Organic compounds -- Synthesis , Mutagenesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4042 , http://hdl.handle.net/10962/d1004103 , Polyphenols , Catechol , Streptomacyes , Organic compounds -- Synthesis , Mutagenesis
- Description: The enzyme polyphenolase, which catalyses the oxidation of phenols to catechols and subsequently dehydrogenates these to o-quinones, is widely distributed in nature. The multicopy plasmid vector pIJ702 contains a mel gene from Streptomyces antibioticus, that codes for the production of a polyphenol oxidase. The plasmid was isolated from Streptomyces lividans 66pIJ702 and subjected to a variety of mutagenic treatments in order to establish a structurefunction relationship for the polyphenolase enzymes. An attempt was made to engineer the polyphenolase enzyme by localized random mutagenesis in vitro of the mel gene on pIJ702, in order to alter properties like productivity, activity and substrate specificity. It was hoped to alter the amino acid sequence of the active site of the enzyme in order to facilitate catalysis in an organic environment. The plasmid was subsequently transformed into a plasmid-free Streptomyces strain, and enzyme production was carried out in batch culture systems, in order to determine the effect of the height treatment, and to isolate and propagate functional polyphenolase mutants for organic synthesis.
- Full Text:
- Date Issued: 1995
- Authors: Naidoo, Michael Joseph
- Date: 1995
- Subjects: Polyphenols , Catechol , Streptomacyes , Organic compounds -- Synthesis , Mutagenesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4042 , http://hdl.handle.net/10962/d1004103 , Polyphenols , Catechol , Streptomacyes , Organic compounds -- Synthesis , Mutagenesis
- Description: The enzyme polyphenolase, which catalyses the oxidation of phenols to catechols and subsequently dehydrogenates these to o-quinones, is widely distributed in nature. The multicopy plasmid vector pIJ702 contains a mel gene from Streptomyces antibioticus, that codes for the production of a polyphenol oxidase. The plasmid was isolated from Streptomyces lividans 66pIJ702 and subjected to a variety of mutagenic treatments in order to establish a structurefunction relationship for the polyphenolase enzymes. An attempt was made to engineer the polyphenolase enzyme by localized random mutagenesis in vitro of the mel gene on pIJ702, in order to alter properties like productivity, activity and substrate specificity. It was hoped to alter the amino acid sequence of the active site of the enzyme in order to facilitate catalysis in an organic environment. The plasmid was subsequently transformed into a plasmid-free Streptomyces strain, and enzyme production was carried out in batch culture systems, in order to determine the effect of the height treatment, and to isolate and propagate functional polyphenolase mutants for organic synthesis.
- Full Text:
- Date Issued: 1995
Fuzzy ideals in commutative rings
- Authors: Sekaran, Rajakrishnar
- Date: 1995
- Subjects: Commutative rings , Fuzzy algebra
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5407 , http://hdl.handle.net/10962/d1005221 , Commutative rings , Fuzzy algebra
- Description: In this thesis, we are concerned with various aspects of fuzzy ideals of commutative rings. The central theorem is that of primary decomposition of a fuzzy ideal as an intersection of fuzzy primary ideals in a commutative Noetherian ring. We establish the existence and the two uniqueness theorems of primary decomposition of any fuzzy ideal with membership value 1 at the zero element. In proving this central result, we build up the necessary tools such as fuzzy primary ideals and the related concept of fuzzy maximal ideals, fuzzy prime ideals and fuzzy radicals. Another approach explores various characterizations of fuzzy ideals, namely, generation and level cuts of fuzzy ideals, relation between fuzzy ideals, congruences and quotient fuzzy rings. We also tie up several authors' seemingly different definitions of fuzzy prime, primary, semiprimary and fuzzy radicals available in the literature and show some of their equivalences and implications, providing counter-examples where certain implications fail.
- Full Text:
- Date Issued: 1995
- Authors: Sekaran, Rajakrishnar
- Date: 1995
- Subjects: Commutative rings , Fuzzy algebra
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5407 , http://hdl.handle.net/10962/d1005221 , Commutative rings , Fuzzy algebra
- Description: In this thesis, we are concerned with various aspects of fuzzy ideals of commutative rings. The central theorem is that of primary decomposition of a fuzzy ideal as an intersection of fuzzy primary ideals in a commutative Noetherian ring. We establish the existence and the two uniqueness theorems of primary decomposition of any fuzzy ideal with membership value 1 at the zero element. In proving this central result, we build up the necessary tools such as fuzzy primary ideals and the related concept of fuzzy maximal ideals, fuzzy prime ideals and fuzzy radicals. Another approach explores various characterizations of fuzzy ideals, namely, generation and level cuts of fuzzy ideals, relation between fuzzy ideals, congruences and quotient fuzzy rings. We also tie up several authors' seemingly different definitions of fuzzy prime, primary, semiprimary and fuzzy radicals available in the literature and show some of their equivalences and implications, providing counter-examples where certain implications fail.
- Full Text:
- Date Issued: 1995
Gender, households and environmental changes in informal settlements in the Eastern Cape Province, South Africa
- Manona, Cecil Wele, Bank, Leslie John, Higginbottom, Karen
- Authors: Manona, Cecil Wele , Bank, Leslie John , Higginbottom, Karen
- Date: 1995
- Subjects: Agricultural laborers -- South Africa -- Eastern Cape -- Economic conditions Agricultural laborers -- South Africa -- Eastern Cape Environmental health -- South Africa Environmental impact statements -- South Africa Environmental policy -- South Africa -- Eastern Cape Household supplies -- South Africa Households -- South Africa
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/1821 , vital:20230 , ISBN 0868103020
- Description: In recent years the number of people living in informal or 'squatter' settlements in South Africa has mushroomed and virtually every small town or city has one or more squatter settlements associated with it, often next door to the formal residential areas. Using field data collected from 1993 in two informal settlements in the Eastern Cape Province of South Africa this study examines, firstly, the ways in which men and women in these communities organise their lives in their households and in the wider society. Secondly, it assesses the physical environment of informal settlements where there is a lack of service infrastructure, especially water, sewerage facilities, refuse removal and roads. Also, it was assumed that the presence of large numbers of people in an informal settlement has a deleterious effect on natural resources like the soil, wood, vegetation and water and that this may have a significant contribution to environmental pollution and degradation. This aspect was also examined. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1995
- Authors: Manona, Cecil Wele , Bank, Leslie John , Higginbottom, Karen
- Date: 1995
- Subjects: Agricultural laborers -- South Africa -- Eastern Cape -- Economic conditions Agricultural laborers -- South Africa -- Eastern Cape Environmental health -- South Africa Environmental impact statements -- South Africa Environmental policy -- South Africa -- Eastern Cape Household supplies -- South Africa Households -- South Africa
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/1821 , vital:20230 , ISBN 0868103020
- Description: In recent years the number of people living in informal or 'squatter' settlements in South Africa has mushroomed and virtually every small town or city has one or more squatter settlements associated with it, often next door to the formal residential areas. Using field data collected from 1993 in two informal settlements in the Eastern Cape Province of South Africa this study examines, firstly, the ways in which men and women in these communities organise their lives in their households and in the wider society. Secondly, it assesses the physical environment of informal settlements where there is a lack of service infrastructure, especially water, sewerage facilities, refuse removal and roads. Also, it was assumed that the presence of large numbers of people in an informal settlement has a deleterious effect on natural resources like the soil, wood, vegetation and water and that this may have a significant contribution to environmental pollution and degradation. This aspect was also examined. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
- Full Text:
- Date Issued: 1995
Geochemical exploration in calcrete terrains
- Authors: Krug, Mark Alan
- Date: 1995 , 2013-10-02
- Subjects: Duricrusts , Silcrete , Geochemical prospecting
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5026 , http://hdl.handle.net/10962/d1006891 , Duricrusts , Silcrete , Geochemical prospecting
- Description: This work takes a look at some of the literature on calcretes and especially the problem of geochemical exploration in calcrete terrains. The conclusion that will be reached is that exploration in calcrete terrains is not futile and that provided the explorationist is aware of the types of calcrete and their genetic implications calcrete can be used as a sampling medium and anomalies can be detected through calcrete (p.1.) , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1995
- Authors: Krug, Mark Alan
- Date: 1995 , 2013-10-02
- Subjects: Duricrusts , Silcrete , Geochemical prospecting
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5026 , http://hdl.handle.net/10962/d1006891 , Duricrusts , Silcrete , Geochemical prospecting
- Description: This work takes a look at some of the literature on calcretes and especially the problem of geochemical exploration in calcrete terrains. The conclusion that will be reached is that exploration in calcrete terrains is not futile and that provided the explorationist is aware of the types of calcrete and their genetic implications calcrete can be used as a sampling medium and anomalies can be detected through calcrete (p.1.) , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1995
Geological characteristics of selected disseminated sediment-hosted gold deposits in Nevada, U.S.A. : in search of an exploration model
- Authors: Skead, Michael Bethel
- Date: 1995 , 2013-10-07
- Subjects: Gold ores -- Geology -- Nevada
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5036 , http://hdl.handle.net/10962/d1007414 , Gold ores -- Geology -- Nevada
- Description: Sediment-hosted disseminated gold deposits in Nevada, western United States are major gold sources and contain reserves in excess of 1 500 metric tons of gold (Percival et aI., 1988). Discovery of these deposit types continues at a pace, with Placer Dome announcing a mojor discovery, Pipeline, to the south of the Gold Acres Mine, along the Battle Mountain - Eureka Trend in 1994 (The Northern Miner, 1994). Host sediments favoured for disseminated gold mineralisation are thinly bedded silty limestones , carbonate debris flows and to a lesser extent shale, chert and sandstone. The distribution of mineralisation is controlled essentially by the intersection of high-angle faults, which acted as conduits for hydrothermal fluids, with favourable host lithologies, anticlines, low-angle faults and other high-angle faults. Geochemical signature for these deposits is simple being Au, Ag, As, Sb, Hg, Tl, Te, F and Ba, but individual element concentrations vary greatly between and within deposits. Age of mineralisation is cause for considerable debate, and ages ranging between isotopic dates of approximately 117 Ma to early to mid-Tertiary (30-40 Ma) are proposed. Most of these deposits are situated along three major trends namely the Carlin, Battle Mountain - Eureka and Getchell trends. The Battle Mountain - Eureka trend and, to a lesser extent the Carlin trend, are defined by major linear aeromagnetic and gravity anomalies , which are believed to reflect deep-seated structures. Most deposits are hosted in autochthonous Devonian, thinly bedded, silty limestones that occur as windows through what is believed to be allochthonous Ordovician siliciclastic sediments, which were transported from west to east along the Roberts Mountains thrust during the late-Devonian Antler Orogeny. However, recent fossil dating of what were thought to be Ordivician siliciclastic sediments, gives a Devonian age. This questions the age of Ordivician sediments at the other deposits and the interpretation of the structural windows in which deposits are located. Fault-bounded, proximal, carbonate debris-flow breccias are now recognised as a major host to mineralisation. These debris flow breccias, together with interbedded carbonate and siliciclastic sediments, carbonaceous sediments and soft sediment deformation are all characteristics of lithologies in pull-apart basins which develop along a major strike slip faults. It is proposed that sediment-hosted disseminated gold mineralisation is controlled by the distribution of deep-seated long-lived, predominantly right-lateral strike-slip faults. It is along these strike-slip faults that syn-sedimentary pull-apart basins developed, within which sediments favoured by epigenetic gold mineralisation were deposited. These pull-apart basins were then overprinted by post-depositional extensional structures, such as negative flower structures. Igneous intrusions and hydrothermal cells have exploited these extensional structures in both compressional and extensional regional tectonic regimes. This model explains the characteristics of the host sediment at many of the deposits, the spatial relationship between igneous intrusion and mineralisation, spanning the period Cretaceous through to mid-Tertiary, the distribution of deposits as districts along major regional trends and why hydrothermal activity is noted between deposit districts but with no complementary mineralisation. Mineralisation is controlled predominantly by high angle structures and although the recent age for mineralisation at the Betze/Post deposit is ~ 117 Ma (Arehart et aI., 1993a), placing it in the compressional Sevier Orogeny, these high-angle structures would be developed within local extensional tectonic domains as described above. This model can, and should, be applied to other areas of the world where similar geological features exist. In exploring for these deposits in Nevada the distribution of Ordovician siliciclastic sediments should be reviewed, especially where spatially associated with deep regional structures. Ordovician sediments have historically been regarded as unfavourable, hence large areas for potential exploration have been ignored but with new ages for these sediments this opens large areas for potential discoveries. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1995
- Authors: Skead, Michael Bethel
- Date: 1995 , 2013-10-07
- Subjects: Gold ores -- Geology -- Nevada
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5036 , http://hdl.handle.net/10962/d1007414 , Gold ores -- Geology -- Nevada
- Description: Sediment-hosted disseminated gold deposits in Nevada, western United States are major gold sources and contain reserves in excess of 1 500 metric tons of gold (Percival et aI., 1988). Discovery of these deposit types continues at a pace, with Placer Dome announcing a mojor discovery, Pipeline, to the south of the Gold Acres Mine, along the Battle Mountain - Eureka Trend in 1994 (The Northern Miner, 1994). Host sediments favoured for disseminated gold mineralisation are thinly bedded silty limestones , carbonate debris flows and to a lesser extent shale, chert and sandstone. The distribution of mineralisation is controlled essentially by the intersection of high-angle faults, which acted as conduits for hydrothermal fluids, with favourable host lithologies, anticlines, low-angle faults and other high-angle faults. Geochemical signature for these deposits is simple being Au, Ag, As, Sb, Hg, Tl, Te, F and Ba, but individual element concentrations vary greatly between and within deposits. Age of mineralisation is cause for considerable debate, and ages ranging between isotopic dates of approximately 117 Ma to early to mid-Tertiary (30-40 Ma) are proposed. Most of these deposits are situated along three major trends namely the Carlin, Battle Mountain - Eureka and Getchell trends. The Battle Mountain - Eureka trend and, to a lesser extent the Carlin trend, are defined by major linear aeromagnetic and gravity anomalies , which are believed to reflect deep-seated structures. Most deposits are hosted in autochthonous Devonian, thinly bedded, silty limestones that occur as windows through what is believed to be allochthonous Ordovician siliciclastic sediments, which were transported from west to east along the Roberts Mountains thrust during the late-Devonian Antler Orogeny. However, recent fossil dating of what were thought to be Ordivician siliciclastic sediments, gives a Devonian age. This questions the age of Ordivician sediments at the other deposits and the interpretation of the structural windows in which deposits are located. Fault-bounded, proximal, carbonate debris-flow breccias are now recognised as a major host to mineralisation. These debris flow breccias, together with interbedded carbonate and siliciclastic sediments, carbonaceous sediments and soft sediment deformation are all characteristics of lithologies in pull-apart basins which develop along a major strike slip faults. It is proposed that sediment-hosted disseminated gold mineralisation is controlled by the distribution of deep-seated long-lived, predominantly right-lateral strike-slip faults. It is along these strike-slip faults that syn-sedimentary pull-apart basins developed, within which sediments favoured by epigenetic gold mineralisation were deposited. These pull-apart basins were then overprinted by post-depositional extensional structures, such as negative flower structures. Igneous intrusions and hydrothermal cells have exploited these extensional structures in both compressional and extensional regional tectonic regimes. This model explains the characteristics of the host sediment at many of the deposits, the spatial relationship between igneous intrusion and mineralisation, spanning the period Cretaceous through to mid-Tertiary, the distribution of deposits as districts along major regional trends and why hydrothermal activity is noted between deposit districts but with no complementary mineralisation. Mineralisation is controlled predominantly by high angle structures and although the recent age for mineralisation at the Betze/Post deposit is ~ 117 Ma (Arehart et aI., 1993a), placing it in the compressional Sevier Orogeny, these high-angle structures would be developed within local extensional tectonic domains as described above. This model can, and should, be applied to other areas of the world where similar geological features exist. In exploring for these deposits in Nevada the distribution of Ordovician siliciclastic sediments should be reviewed, especially where spatially associated with deep regional structures. Ordovician sediments have historically been regarded as unfavourable, hence large areas for potential exploration have been ignored but with new ages for these sediments this opens large areas for potential discoveries. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 1995
HPLC analysis and pharmacokinetics of cyclizine
- Authors: Walker, Roderick Bryan
- Date: 1995
- Subjects: High performance liquid chromatography Piperazine Pharmacokinetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3801 , http://hdl.handle.net/10962/d1003279
- Description: The investigations detailed in this dissertation have been conducted to address the paucity of pharmacokinetic information, in published literature, pertaining to cyclizine. The areas of investigation have included the selective quantitation of both cyclizine and its demethylated metabolite, norcyclizine in serum and urine, assessment of stability of both compounds in stored biological samples, dosage form analysis, dissolution rate testing of tablets, and bioavailability and pharmacokinetics following administration of an intravenous solution, and tablets to humans. High-performance liquid chromatography (HPLC) was used as the main analytical technique throughout these studies. An original HPLC method employing ultraviolet detection with a limit of quantitation of 5μg/ℓ was developed for the determination of cyclizine in serum and both cyclizine and norcyclizine in urine, Solid-phase extraction using extraction columns packed with reversed-phase C18 material, and followed by a simple phase-separation step proved successful for the accurate and precise isolation of the compounds. The validated method was applied to the analysis of serum and urine samples from a pilot study in which a single volunteer was administered 50mg of cyclizine hydrochloride. Several samples collected during the pilot study revealed the presence of both drug and metabolite in concentrations below the limit of detection. In order to improve the selectivity and sensitivity of the analytical method an HPLC method with electrochemical detection operating in the "oxidative-screen" mode was developed. The solid-phase extraction procedure was modified slightly and the method found to be precise, accurate, selective and highly sensitive with a limit of quantitation of Iμg/g/l for both cyclizine and norcyclizine in both serum and urine. This method was applied to the determination of both compounds after intravenous and oral administration of cyclizine to humans. HPLC with electrochemical detection was used for the analysis of samples collected during dissolution studies on the batch of tablets used for pharmacokinetic studies. In addition, this method was used to assess content uniformity of the tablets and of samples from the batch of intravenous ampoules of cyclizine lactate. Dissolution studies showed that all tablets tested passed the compendial specifications for cyclizine. Content uniformity assessment revealed that within-batch uniformity existed for both the tablets and ampoules and, therefore, variations in pharmacokinetic parameters for the drug would more than likely be as a result of inter- and intra-individual variability within the subject population. Pharmacokinetic information for cyclizine was obtained following administration of an intravenous bolus dose of cyclizine lactate as a solution, oral administration of cyclizine hydrochloride as a single dose of 50mg and as fixed multiple doses of 50mg every 8 hours for five days. Further information was acquired following administration of single doses of 100mg and 150mg cyclizine hydrochloride. Data collected from these studies were evaluated using both compartmental and non-compartmental techniques. Cyclizine was rapidly absorbed following oral administration with mean kₐ = 1.54 hr⁻¹ and was found to have an absolute bioavailability (F) of 0.47. The presence of norcyclizine in serum following oral and not intravenous dosing suggests cyclizine is susceptible to "first-pass" metabolism in either the gut wall or the I iver. Mean ClTOT determined following the intravenous dose was 0.865 ℓ/hr/kg. The mean ClTOT of 0.823 ℓ/hr/kg calculated following oral dosing, using a unique value of F for each subject compared favourahly with that obtained following intravenous dosing. Renal clearance of cyclizine is negligihle indicating that non-renal routes of elimination account for the majority of removal of cyclizine form the body. Cyclizine is extensively distributed and the mean Vz following an intravenous dose was 16.70 ℓ/kg. This value is lower than that calculated from all oral studies from which the mean Vz was determined to be 25.74 ℓ/kg. Cyclizine is eliminated slowly with a mean elimination t½ = 20.11 hours. Cyclizine dose not appear to follow dosedependent kinetics and therefore, inability to predict steady state levels are more than likely due to accumulation as a result of frequent dosing rather than saturation of elimination mechanisms. Modelling of intravenous data to one-compartment (lBCM), two-compartment (2BCM) and threecompartment models indicated that the pharmacokinetics of cyclizine can be adequately described by a 3BCM. The drug is rapidly distributed into a "shallow" peripheral compartment (α = 9.44 hr⁻¹ , and k₂₁ = 2.09 hr⁻¹ ), and slowly distributed to the "deep" peripheral compartment (β = 0.451 hr⁻¹ and k₃₁ = 0.120 hr⁻¹ ). Modelling of all oral data indicated that a 2BCM best described the pharmacokinetics of the drug, however, distribution to the peripheral compartment is not as rapid as to the "shallow" peripheral compartment following the intravenous dose. Mean distribution parameters were α = 0.64 hr⁻¹1 and, k₂₁ = 0.39 hr⁻¹. Mean CITOT following intravenous dosing of 0.70 ℓ/hr/kg was similar to the mean CIToT of 0.73 ℓ/hr/kg determined after oral dosing. The mean distribution volume at steady state determined following intravenous dosing (17.78 ℓ/kg) was lower than that obtained from the oral studies (25.52 ℓ/kg). The mean terminal elimination half-lives calculated for cyclizine following fitting of intravenous and oral data was 25.09 hours. In general, mean pharmacokinetic parameters calculated following titting of data to a 2BCM after oral administration correlate closely with those calculated using non-compartmental techniques. However, the pharmacokinetics following intravenous dosing are better described by a 3BCM and a close correlation between parameters estimated using noncompartmental techniques and compartmental techniques is evident when a 3BCM model is used.
- Full Text:
- Date Issued: 1995
- Authors: Walker, Roderick Bryan
- Date: 1995
- Subjects: High performance liquid chromatography Piperazine Pharmacokinetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3801 , http://hdl.handle.net/10962/d1003279
- Description: The investigations detailed in this dissertation have been conducted to address the paucity of pharmacokinetic information, in published literature, pertaining to cyclizine. The areas of investigation have included the selective quantitation of both cyclizine and its demethylated metabolite, norcyclizine in serum and urine, assessment of stability of both compounds in stored biological samples, dosage form analysis, dissolution rate testing of tablets, and bioavailability and pharmacokinetics following administration of an intravenous solution, and tablets to humans. High-performance liquid chromatography (HPLC) was used as the main analytical technique throughout these studies. An original HPLC method employing ultraviolet detection with a limit of quantitation of 5μg/ℓ was developed for the determination of cyclizine in serum and both cyclizine and norcyclizine in urine, Solid-phase extraction using extraction columns packed with reversed-phase C18 material, and followed by a simple phase-separation step proved successful for the accurate and precise isolation of the compounds. The validated method was applied to the analysis of serum and urine samples from a pilot study in which a single volunteer was administered 50mg of cyclizine hydrochloride. Several samples collected during the pilot study revealed the presence of both drug and metabolite in concentrations below the limit of detection. In order to improve the selectivity and sensitivity of the analytical method an HPLC method with electrochemical detection operating in the "oxidative-screen" mode was developed. The solid-phase extraction procedure was modified slightly and the method found to be precise, accurate, selective and highly sensitive with a limit of quantitation of Iμg/g/l for both cyclizine and norcyclizine in both serum and urine. This method was applied to the determination of both compounds after intravenous and oral administration of cyclizine to humans. HPLC with electrochemical detection was used for the analysis of samples collected during dissolution studies on the batch of tablets used for pharmacokinetic studies. In addition, this method was used to assess content uniformity of the tablets and of samples from the batch of intravenous ampoules of cyclizine lactate. Dissolution studies showed that all tablets tested passed the compendial specifications for cyclizine. Content uniformity assessment revealed that within-batch uniformity existed for both the tablets and ampoules and, therefore, variations in pharmacokinetic parameters for the drug would more than likely be as a result of inter- and intra-individual variability within the subject population. Pharmacokinetic information for cyclizine was obtained following administration of an intravenous bolus dose of cyclizine lactate as a solution, oral administration of cyclizine hydrochloride as a single dose of 50mg and as fixed multiple doses of 50mg every 8 hours for five days. Further information was acquired following administration of single doses of 100mg and 150mg cyclizine hydrochloride. Data collected from these studies were evaluated using both compartmental and non-compartmental techniques. Cyclizine was rapidly absorbed following oral administration with mean kₐ = 1.54 hr⁻¹ and was found to have an absolute bioavailability (F) of 0.47. The presence of norcyclizine in serum following oral and not intravenous dosing suggests cyclizine is susceptible to "first-pass" metabolism in either the gut wall or the I iver. Mean ClTOT determined following the intravenous dose was 0.865 ℓ/hr/kg. The mean ClTOT of 0.823 ℓ/hr/kg calculated following oral dosing, using a unique value of F for each subject compared favourahly with that obtained following intravenous dosing. Renal clearance of cyclizine is negligihle indicating that non-renal routes of elimination account for the majority of removal of cyclizine form the body. Cyclizine is extensively distributed and the mean Vz following an intravenous dose was 16.70 ℓ/kg. This value is lower than that calculated from all oral studies from which the mean Vz was determined to be 25.74 ℓ/kg. Cyclizine is eliminated slowly with a mean elimination t½ = 20.11 hours. Cyclizine dose not appear to follow dosedependent kinetics and therefore, inability to predict steady state levels are more than likely due to accumulation as a result of frequent dosing rather than saturation of elimination mechanisms. Modelling of intravenous data to one-compartment (lBCM), two-compartment (2BCM) and threecompartment models indicated that the pharmacokinetics of cyclizine can be adequately described by a 3BCM. The drug is rapidly distributed into a "shallow" peripheral compartment (α = 9.44 hr⁻¹ , and k₂₁ = 2.09 hr⁻¹ ), and slowly distributed to the "deep" peripheral compartment (β = 0.451 hr⁻¹ and k₃₁ = 0.120 hr⁻¹ ). Modelling of all oral data indicated that a 2BCM best described the pharmacokinetics of the drug, however, distribution to the peripheral compartment is not as rapid as to the "shallow" peripheral compartment following the intravenous dose. Mean distribution parameters were α = 0.64 hr⁻¹1 and, k₂₁ = 0.39 hr⁻¹. Mean CITOT following intravenous dosing of 0.70 ℓ/hr/kg was similar to the mean CIToT of 0.73 ℓ/hr/kg determined after oral dosing. The mean distribution volume at steady state determined following intravenous dosing (17.78 ℓ/kg) was lower than that obtained from the oral studies (25.52 ℓ/kg). The mean terminal elimination half-lives calculated for cyclizine following fitting of intravenous and oral data was 25.09 hours. In general, mean pharmacokinetic parameters calculated following titting of data to a 2BCM after oral administration correlate closely with those calculated using non-compartmental techniques. However, the pharmacokinetics following intravenous dosing are better described by a 3BCM and a close correlation between parameters estimated using noncompartmental techniques and compartmental techniques is evident when a 3BCM model is used.
- Full Text:
- Date Issued: 1995
Hydroclimatic trends, sediment sources and geomorphic response in the Bell River catchment, eastern Cape Drakensberg, South Africa
- Dollar, Evan S J, Rowntree, Kate M
- Authors: Dollar, Evan S J , Rowntree, Kate M
- Date: 1995
- Language: English
- Type: Article
- Identifier: vital:6677 , http://hdl.handle.net/10962/d1006655
- Description: The Bell River in the Eastern Cape Drakensberg of South Africa has shown recent signs of channel instability as evidenced by avulsion, sinuosity reductions, gradient steepening and general channel instability. Analysis of rainfall data did not provide evidence for progressive long term change in rainfall pattern for the catchment. However, annual and seasonal rainfall cycles with variance peaks every 16-19 years were found, from which it can be inferred that flood events following years of below average rainfall may cross the threshold limit for channel stability. Channel instability is often followed by a major flood event after sustained low rainfall periods, a sequence referred to as the Flood and Drought Dominated Regimes by Warner (1987). Evidence presented also indicates an increase in catchment erosion in the past century with attendant sediment production increases to the channel. This may be due to catchment land use and management practices (following settlement by commercial farmers) superimposed on long term climatic changes. The conclusions are that catchment and channel processes are inseparable, and that disequilibrium in the catchment will be transferred to the channel.
- Full Text:
- Date Issued: 1995
- Authors: Dollar, Evan S J , Rowntree, Kate M
- Date: 1995
- Language: English
- Type: Article
- Identifier: vital:6677 , http://hdl.handle.net/10962/d1006655
- Description: The Bell River in the Eastern Cape Drakensberg of South Africa has shown recent signs of channel instability as evidenced by avulsion, sinuosity reductions, gradient steepening and general channel instability. Analysis of rainfall data did not provide evidence for progressive long term change in rainfall pattern for the catchment. However, annual and seasonal rainfall cycles with variance peaks every 16-19 years were found, from which it can be inferred that flood events following years of below average rainfall may cross the threshold limit for channel stability. Channel instability is often followed by a major flood event after sustained low rainfall periods, a sequence referred to as the Flood and Drought Dominated Regimes by Warner (1987). Evidence presented also indicates an increase in catchment erosion in the past century with attendant sediment production increases to the channel. This may be due to catchment land use and management practices (following settlement by commercial farmers) superimposed on long term climatic changes. The conclusions are that catchment and channel processes are inseparable, and that disequilibrium in the catchment will be transferred to the channel.
- Full Text:
- Date Issued: 1995