Ammophila arenaria (L.) Link (marram grass) in South Africa and its potential invasiveness
- Authors: Hertling, Ursula Margret
- Date: 1998
- Subjects: Grasses -- South Africa Alien plants -- South Africa Sand dune plants -- South Africa Grasses -- Ecology -- South Africa Sand dune ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4198 , http://hdl.handle.net/10962/d1003767
- Description: Ammophila arenaria (L.) Link is a European sand binding plant which was introduced to South Africa in the 1870's for the purpose of dune stabilisation. Because of its known invasiveness along the west coast of North America, and the problems South African ecosystems experience with alien invader plants, it was deemed necessary to study the biology and ecology of this species in South Africa. The aim of this thesis is to establish the potential invasiveness of A. arenaria on Cape coastal dunes and assess whether its use for dune stabilisation is still justifiable. A. arenaria occurs nowadays between the Langebaan area on the west coast and Gonubie in the Eastern Cape. Although widespread, the grass appears to occur only in areas where it has been planted. Its unaided spread may be prevented by adverse climatic conditions. Studies on the community biology of South African A. arenaria communities as compared to indigenous dune plant communities and natural A. arenaria communities in Europe cannot confirm the aggressive behaviour that A. arenaria shows in California and Oregon. In South Africa, A. arenaria does not exert strong floristic control over other species or outcompete and replace them, neither does it alter the topography of South African beaches and dunes. It forms weaker species associations and tends to develop communities of little species variability along the coast, thereby proving its alienness in South Africa, but this does not imply its invasiveness. Studies on succession of A. arenaria stabilisation areas show that monospecific A. arenaria plantings can be succeeded by a species-rich indigenous dune scrub or dune fynbos within a few decades. Plant-parasitic nematodes have been recorded, which may play an important role in the succession of A. arenaria stands in South Africa as was observed in Europe. Monitoring of A. arenaria communities and indigenous communities over nearly three years shows that A. arenaria is not spreading and replacing indigenous plants but in fact rather being replaced by the latter. A. arenaria profits from a superior sand burial tolerance but is affected by adverse climatic factors, mostly the lack of rainfall and strong radiation. In comparison to the indigenous dune grasses Thinopyrum distichum and Ehrharta villosa, it does not show any superior demographic traits such as an unusually high growth rate or large aboveground biomass production. Although A. arenaria produces viable seed in South Africa, the indigenous grasses show better germination and seedling establishment in the field. This study indicates that A. arenaria is not invasive in South Africa, nor likely to become an invader species in the near future. However, more research is required to confirm these results and more caution recommended regarding the further use of this alien grass for dune stabilisation.
- Full Text:
- Date Issued: 1998
- Authors: Hertling, Ursula Margret
- Date: 1998
- Subjects: Grasses -- South Africa Alien plants -- South Africa Sand dune plants -- South Africa Grasses -- Ecology -- South Africa Sand dune ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4198 , http://hdl.handle.net/10962/d1003767
- Description: Ammophila arenaria (L.) Link is a European sand binding plant which was introduced to South Africa in the 1870's for the purpose of dune stabilisation. Because of its known invasiveness along the west coast of North America, and the problems South African ecosystems experience with alien invader plants, it was deemed necessary to study the biology and ecology of this species in South Africa. The aim of this thesis is to establish the potential invasiveness of A. arenaria on Cape coastal dunes and assess whether its use for dune stabilisation is still justifiable. A. arenaria occurs nowadays between the Langebaan area on the west coast and Gonubie in the Eastern Cape. Although widespread, the grass appears to occur only in areas where it has been planted. Its unaided spread may be prevented by adverse climatic conditions. Studies on the community biology of South African A. arenaria communities as compared to indigenous dune plant communities and natural A. arenaria communities in Europe cannot confirm the aggressive behaviour that A. arenaria shows in California and Oregon. In South Africa, A. arenaria does not exert strong floristic control over other species or outcompete and replace them, neither does it alter the topography of South African beaches and dunes. It forms weaker species associations and tends to develop communities of little species variability along the coast, thereby proving its alienness in South Africa, but this does not imply its invasiveness. Studies on succession of A. arenaria stabilisation areas show that monospecific A. arenaria plantings can be succeeded by a species-rich indigenous dune scrub or dune fynbos within a few decades. Plant-parasitic nematodes have been recorded, which may play an important role in the succession of A. arenaria stands in South Africa as was observed in Europe. Monitoring of A. arenaria communities and indigenous communities over nearly three years shows that A. arenaria is not spreading and replacing indigenous plants but in fact rather being replaced by the latter. A. arenaria profits from a superior sand burial tolerance but is affected by adverse climatic factors, mostly the lack of rainfall and strong radiation. In comparison to the indigenous dune grasses Thinopyrum distichum and Ehrharta villosa, it does not show any superior demographic traits such as an unusually high growth rate or large aboveground biomass production. Although A. arenaria produces viable seed in South Africa, the indigenous grasses show better germination and seedling establishment in the field. This study indicates that A. arenaria is not invasive in South Africa, nor likely to become an invader species in the near future. However, more research is required to confirm these results and more caution recommended regarding the further use of this alien grass for dune stabilisation.
- Full Text:
- Date Issued: 1998
An account of second language teaching and learning in a multi-standard farm school classroom, utilising an ethnographic approach
- Authors: Krause, Siobbhan Karen
- Date: 1998
- Subjects: English language -- Study and teaching -- South Africa -- Foreign speakers Rural schools -- South Africa Community and school -- South Africa English language -- Study and teaching -- Foreign speakers Education, Rural -- South Africa Black people -- Education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1416 , http://hdl.handle.net/10962/d1003297
- Description: Multi-standard classrooms are a distinctive feature of many South African farm schools. This study adopts an ethnographic approach in order to explore how classroom life in one particular Eastern Cape multistandard farm school classroom is shaped by a set of circumstances which influence the nature of teaching and learning in that classroom. The research focuses on the extent to which the difficulties associated with teaching a multi-standard class dictate the teacher's approach to lesson planning and style of teaching and how the resultant pattern of interaction influences language learning within a second language context. Data from a variety of sources, obtained primarily through classroom observations, interviews and questionnaires, is presented. Findings tend to indicate that the demands made on the teachers and pupils in terms of large, multi-standard classes, second language medium of instruction and lack of teaching aids, encourages the use of rote learning techniques which are not conducive to language learning. The pattern of interaction that predominates is a teacher-led series of questions and prompts followed by a chorus response from the pupils. This pattern tends to undermine the communicative aspects of language learning by reducing natural interaction and results in pupil passivity as language learners.
- Full Text:
- Date Issued: 1998
- Authors: Krause, Siobbhan Karen
- Date: 1998
- Subjects: English language -- Study and teaching -- South Africa -- Foreign speakers Rural schools -- South Africa Community and school -- South Africa English language -- Study and teaching -- Foreign speakers Education, Rural -- South Africa Black people -- Education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1416 , http://hdl.handle.net/10962/d1003297
- Description: Multi-standard classrooms are a distinctive feature of many South African farm schools. This study adopts an ethnographic approach in order to explore how classroom life in one particular Eastern Cape multistandard farm school classroom is shaped by a set of circumstances which influence the nature of teaching and learning in that classroom. The research focuses on the extent to which the difficulties associated with teaching a multi-standard class dictate the teacher's approach to lesson planning and style of teaching and how the resultant pattern of interaction influences language learning within a second language context. Data from a variety of sources, obtained primarily through classroom observations, interviews and questionnaires, is presented. Findings tend to indicate that the demands made on the teachers and pupils in terms of large, multi-standard classes, second language medium of instruction and lack of teaching aids, encourages the use of rote learning techniques which are not conducive to language learning. The pattern of interaction that predominates is a teacher-led series of questions and prompts followed by a chorus response from the pupils. This pattern tends to undermine the communicative aspects of language learning by reducing natural interaction and results in pupil passivity as language learners.
- Full Text:
- Date Issued: 1998
An assessment of the South African east coast linefishery from Kei Mouth to Stil Bay
- Authors: Brouwer, Stephen Leonard
- Date: 1998
- Subjects: Fisheries -- Research -- South Africa , Fisheries -- Environmental aspects -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5233 , http://hdl.handle.net/10962/d1005076 , Fisheries -- Research -- South Africa , Fisheries -- Environmental aspects -- Research -- South Africa
- Description: During the period April 1994 and February 1996 as part of an investigation into the national Iinefishery, the east coast shore fishery and the recreational and commercial ski-boat fisheries were surveyed, at eight sites between Kei Mouth in the East and Stil Bay in the West. Roving creel, access point and aerial surveys were used. A questionnaire was developed for each sector to gather data on catch and effort, fisher demographics, economics, fisher attitudes towards, and knowledge of, the current management regulations and assess the efficacy of the fisheries inspectorate. During the access point survey the catch of 3273 fishers was inspected and 1556 interviews were conducted. Questionnaires were conducted on 118 recreational ski-boaters and the catch of 165 boats was inspected. 96 commercial skippers were interviewed and 230 had their catch inspected. Three aerial surveys of the entire area were conducted during which a total of 1067 shore fishers were counted giving a shore fisher density of 0.39 fishers.km⁻¹. The majority (99%) of participants in all sectors of the linefishery were male. The greatest number of participants were white, shore fishery 77% recreational ski-boat 98% commercial skiboat 89%, followed by coloured, asian and black people. To a large extent this reflects the income of various racial groups. Most fishers supported the current linefish management plan. However, when tested on their knowledge of the size limits, bag limits and closed seasons of their target species many shore fishers (59%) did not know them and a high proportion of fishers in all sectors had disobeyed at least one of the regulations (shore 50%, recreational ski-boat 70%, commercial ski-boat 56%). When compared to historical data the present catch per unit effort (CPUE) in all sectors has decreased. Most interviewees in the various sectors did not accept responsibility for the decline in CPUE, but attributed it to three principal reasons vis their perceived direct competitors, trawling and pollution. Analysis of the catch revealed that all sectors were multispecies fisheries, with each sector being characterised by a small number of target species. Catch composition differed significantly between the shore and ski-boat sectors, but there was significant overlap between the two skiboat sectors. Analysis of the catch in comparison to that reported to the National Marine Linefish System (NMLS) revealed that there was a substantial degree of under-reporting. There was little seasonal difference in effort in the shore fishery while the recreational ski-boat effort was highest in the summer and the commercial ski-boat effort was high in the winter. Effort in the shore and recreational ski-boat fisheries was concentrated over weekends while the commercial ski-boat effort was highest during weekdays. Total effort for the entire area was estimated at 903 186 (±1913) fisher days per annum in the shore fishery, 24 357 (±685) recreational ski-boat fisher days and 64 266 (±1686) commercial ski-boat fisher days. Expenditure and capital investment in the various sectors was calculated, as were earnings of the participants in the commercial ski-boat sector. The linefishery in the Eastern Cape was estimated to have a minimum capital investment in excess of R210 million and more than R32 million is spent annually on running costs. The commercial ski-boat fishery directly employed an estimated 3184 people. The economic implications of changes in CPUE for the commercial ski-boat fishery are considered, as are the benefits of a recreational angling licence. Management of the linefishery is discussed in relation to the findings of this study.
- Full Text:
- Date Issued: 1998
- Authors: Brouwer, Stephen Leonard
- Date: 1998
- Subjects: Fisheries -- Research -- South Africa , Fisheries -- Environmental aspects -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5233 , http://hdl.handle.net/10962/d1005076 , Fisheries -- Research -- South Africa , Fisheries -- Environmental aspects -- Research -- South Africa
- Description: During the period April 1994 and February 1996 as part of an investigation into the national Iinefishery, the east coast shore fishery and the recreational and commercial ski-boat fisheries were surveyed, at eight sites between Kei Mouth in the East and Stil Bay in the West. Roving creel, access point and aerial surveys were used. A questionnaire was developed for each sector to gather data on catch and effort, fisher demographics, economics, fisher attitudes towards, and knowledge of, the current management regulations and assess the efficacy of the fisheries inspectorate. During the access point survey the catch of 3273 fishers was inspected and 1556 interviews were conducted. Questionnaires were conducted on 118 recreational ski-boaters and the catch of 165 boats was inspected. 96 commercial skippers were interviewed and 230 had their catch inspected. Three aerial surveys of the entire area were conducted during which a total of 1067 shore fishers were counted giving a shore fisher density of 0.39 fishers.km⁻¹. The majority (99%) of participants in all sectors of the linefishery were male. The greatest number of participants were white, shore fishery 77% recreational ski-boat 98% commercial skiboat 89%, followed by coloured, asian and black people. To a large extent this reflects the income of various racial groups. Most fishers supported the current linefish management plan. However, when tested on their knowledge of the size limits, bag limits and closed seasons of their target species many shore fishers (59%) did not know them and a high proportion of fishers in all sectors had disobeyed at least one of the regulations (shore 50%, recreational ski-boat 70%, commercial ski-boat 56%). When compared to historical data the present catch per unit effort (CPUE) in all sectors has decreased. Most interviewees in the various sectors did not accept responsibility for the decline in CPUE, but attributed it to three principal reasons vis their perceived direct competitors, trawling and pollution. Analysis of the catch revealed that all sectors were multispecies fisheries, with each sector being characterised by a small number of target species. Catch composition differed significantly between the shore and ski-boat sectors, but there was significant overlap between the two skiboat sectors. Analysis of the catch in comparison to that reported to the National Marine Linefish System (NMLS) revealed that there was a substantial degree of under-reporting. There was little seasonal difference in effort in the shore fishery while the recreational ski-boat effort was highest in the summer and the commercial ski-boat effort was high in the winter. Effort in the shore and recreational ski-boat fisheries was concentrated over weekends while the commercial ski-boat effort was highest during weekdays. Total effort for the entire area was estimated at 903 186 (±1913) fisher days per annum in the shore fishery, 24 357 (±685) recreational ski-boat fisher days and 64 266 (±1686) commercial ski-boat fisher days. Expenditure and capital investment in the various sectors was calculated, as were earnings of the participants in the commercial ski-boat sector. The linefishery in the Eastern Cape was estimated to have a minimum capital investment in excess of R210 million and more than R32 million is spent annually on running costs. The commercial ski-boat fishery directly employed an estimated 3184 people. The economic implications of changes in CPUE for the commercial ski-boat fishery are considered, as are the benefits of a recreational angling licence. Management of the linefishery is discussed in relation to the findings of this study.
- Full Text:
- Date Issued: 1998
An examination of patients' responses to framework breaks in psychotherapy in an institutional context
- Authors: Rees, Christopher Lewis
- Date: 1998
- Subjects: Psychotherapy patients Psychotherapy -- Research Psychotherapy Case studies Psychiatric hospital care
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3042 , http://hdl.handle.net/10962/d1002551
- Description: This study examines the workings of the ground rules which make up the framework of psychotherapy, in an institutional context, by analysing transcripts of twelve audio taped sessions of therapy conducted in a psychiatric hospital. The breaks in the ground rules of the sessions are noted and the patients' responses to these breaks are analysed using Langs's (1982, 1988) method for decoding patients' material, suitably modified for use as a hermeneutic research method. Although all of the ground rules are broken in the institutional context, only one of the ten ground rules appears to be essentially affected by this particular institutional context. Other ground rules are broken out of choice of technique or through error. The institutional context has a structural impact only on the ground rule requiring a one to one relationship with privacy and confidentiality and this ground rule is transgressed in a number of ways in all twelve sessions examined in this study. However the patients' responses to this breach only occur in ways predicted by communicative theory when the break in the ground rule involves actual entry into the therapy space by another person. Other contraventions to this ground rule that do not involve such an entry do not elicit the predicted patient responses. The many other ground rule breaks occurring in the institutional context evoke the predicted responses in the patients' material. In the study, no therapist interventions are found to comply with the communicative therapy requirements for sound interventions; concomitantly it was found that no therapist interventions receive the required derivative validation. The results indicate that it is possible to conduct therapy of a substantially secure frame variety in this institutional context with minimum effort on the part of therapists and given proper training and supervision of therapists in the techniques of communicative psychotherapy. Furthermore the results lend weight to the importance of the communicative methodology for listening to patients' material in psychotherapy in an institutional context. However, further rigorous study of competently performed therapy, executed within the context of a secure frame within an institutional context, is needed in order to demonstrate the benefits of the communicative psychotherapy interventions and interpretations in this context.
- Full Text:
- Date Issued: 1998
- Authors: Rees, Christopher Lewis
- Date: 1998
- Subjects: Psychotherapy patients Psychotherapy -- Research Psychotherapy Case studies Psychiatric hospital care
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3042 , http://hdl.handle.net/10962/d1002551
- Description: This study examines the workings of the ground rules which make up the framework of psychotherapy, in an institutional context, by analysing transcripts of twelve audio taped sessions of therapy conducted in a psychiatric hospital. The breaks in the ground rules of the sessions are noted and the patients' responses to these breaks are analysed using Langs's (1982, 1988) method for decoding patients' material, suitably modified for use as a hermeneutic research method. Although all of the ground rules are broken in the institutional context, only one of the ten ground rules appears to be essentially affected by this particular institutional context. Other ground rules are broken out of choice of technique or through error. The institutional context has a structural impact only on the ground rule requiring a one to one relationship with privacy and confidentiality and this ground rule is transgressed in a number of ways in all twelve sessions examined in this study. However the patients' responses to this breach only occur in ways predicted by communicative theory when the break in the ground rule involves actual entry into the therapy space by another person. Other contraventions to this ground rule that do not involve such an entry do not elicit the predicted patient responses. The many other ground rule breaks occurring in the institutional context evoke the predicted responses in the patients' material. In the study, no therapist interventions are found to comply with the communicative therapy requirements for sound interventions; concomitantly it was found that no therapist interventions receive the required derivative validation. The results indicate that it is possible to conduct therapy of a substantially secure frame variety in this institutional context with minimum effort on the part of therapists and given proper training and supervision of therapists in the techniques of communicative psychotherapy. Furthermore the results lend weight to the importance of the communicative methodology for listening to patients' material in psychotherapy in an institutional context. However, further rigorous study of competently performed therapy, executed within the context of a secure frame within an institutional context, is needed in order to demonstrate the benefits of the communicative psychotherapy interventions and interpretations in this context.
- Full Text:
- Date Issued: 1998
An exploration of the psychological significance of soap opera viewing
- Authors: Moodley, Prevan
- Date: 1998
- Subjects: Television -- Psychological aspects , Television soap operas -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3023 , http://hdl.handle.net/10962/d1002532 , Television -- Psychological aspects , Television soap operas -- Psychological aspects
- Description: In traditional research approaches, soap opera viewing has been studied quantitatively. Such studies ignore the subjectivities, the sociocultural contexts, and life contexts of individual viewers. To account for such shortcomings and to offer a qualitative research approach, an investigation was conducted into the engagement that viewers have with a particular soap opera, The bold and the beautiful. The collective case study research method was used. Three subjects were interviewed using in-depth phenomenological interviewing and the data obtained was subjected to.a hermeneutic method of investigation. This involved using a reading guide that extracted firstly, how pleasure is experienced in soap opera viewing, and secondly how the viewers' interpretations of the soap opera are linked to their everyday life contexts. Pleasure was found to be related to experiencing the soap opera world as real, the social context of the viewer, the openness of the text, selecting textual elements, identification and opening up the viewer's world. The viewers' interpretations were related to their life contexts in terms of the meanings that were constructed around emotions, identities, interpersonal relations and a cultural interface. Most notable for the South African context, is that viewing The bold and the beautiful provides a cultural interface because African identities are brought to this practice.
- Full Text:
- Date Issued: 1998
- Authors: Moodley, Prevan
- Date: 1998
- Subjects: Television -- Psychological aspects , Television soap operas -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3023 , http://hdl.handle.net/10962/d1002532 , Television -- Psychological aspects , Television soap operas -- Psychological aspects
- Description: In traditional research approaches, soap opera viewing has been studied quantitatively. Such studies ignore the subjectivities, the sociocultural contexts, and life contexts of individual viewers. To account for such shortcomings and to offer a qualitative research approach, an investigation was conducted into the engagement that viewers have with a particular soap opera, The bold and the beautiful. The collective case study research method was used. Three subjects were interviewed using in-depth phenomenological interviewing and the data obtained was subjected to.a hermeneutic method of investigation. This involved using a reading guide that extracted firstly, how pleasure is experienced in soap opera viewing, and secondly how the viewers' interpretations of the soap opera are linked to their everyday life contexts. Pleasure was found to be related to experiencing the soap opera world as real, the social context of the viewer, the openness of the text, selecting textual elements, identification and opening up the viewer's world. The viewers' interpretations were related to their life contexts in terms of the meanings that were constructed around emotions, identities, interpersonal relations and a cultural interface. Most notable for the South African context, is that viewing The bold and the beautiful provides a cultural interface because African identities are brought to this practice.
- Full Text:
- Date Issued: 1998
An investigation into factors influencing immersion in interactive virtual reality environments
- Bangay, Shaun D, Preston, Louise
- Authors: Bangay, Shaun D , Preston, Louise
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432864 , vital:72908 , https://pubmed.ncbi.nlm.nih.gov/10350927/
- Description: Two interactive virtual reality environments were used to identify factors that may affect, or be affected by, the degree of immersion in a virtual world. In particular, the level of stress in a "swimming with dolphins" simulation is measured, as is the degree of simulator sickness resulting form a virtual roller coaster. Analysis of the results indicates that a relationship between the degree of immersion and the following factors: excitement, comfort, quality and age. The following factors are found to depend on the degree of immersion: simulator sickness, control, excitement and desire to repeat the experience.
- Full Text:
- Date Issued: 1998
- Authors: Bangay, Shaun D , Preston, Louise
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432864 , vital:72908 , https://pubmed.ncbi.nlm.nih.gov/10350927/
- Description: Two interactive virtual reality environments were used to identify factors that may affect, or be affected by, the degree of immersion in a virtual world. In particular, the level of stress in a "swimming with dolphins" simulation is measured, as is the degree of simulator sickness resulting form a virtual roller coaster. Analysis of the results indicates that a relationship between the degree of immersion and the following factors: excitement, comfort, quality and age. The following factors are found to depend on the degree of immersion: simulator sickness, control, excitement and desire to repeat the experience.
- Full Text:
- Date Issued: 1998
An investigation into the antioxidative potential and regulatory aspects of liver tryptophan 2,3-dioxygenase by tryptophan and related analogues
- Authors: Antunes, Ana Paula Martins
- Date: 1998
- Subjects: Tryptophan -- Physiological effect , Antioxidants , Liver
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4010 , http://hdl.handle.net/10962/d1004070 , Tryptophan -- Physiological effect , Antioxidants , Liver
- Description: The amino acid, tryptophan, obtained through dietary means, is metabolised by the enzymes tryptophan 2,3-dioxygenase (TDO), indoleamine 2,3-dioxygenase (IDO) and tryptophan hydroxylase. All the enzymes have an effect on circulating tryptophan levels, especially TDO, since it is the major site of tryptophan catabolism in the liver and results in the production of kynurenine metabolites, viz. kynurenine, kynurenic acid, 3-hydroxyanthranilic acid and quinolinic acid. Extrahepatically, IDO is responsible for the synthesis of the kynurenine metabolites. Tryptophan 2,3-dioxygenase and IDO activity is increased by hormones or substrates such as tryptophan, and inflammation, in the case of IDO. Tryptophan availability for serotonin (5-HT) synthesis by the enzyme tryptophan hydroxylase is primarily dependent on TDO activity. A study was attempted in order to ascertain whether any of the endogenous metabolites of the kynurenine and serotonergic pathways would be able to inhibit TDO activity. Results showed that although the kynurenines had no effect, the indoleamines, except for the indoleacetic acids, were able to reduce TDO activity. 6-Methoxy-2-benzoxazolinone (6-MBOA), a structural analogue to melatonin, was the most potent inhibitor with a reduction in activity of 55 % compared with the control. The pineal gland in the rat brain has been shown to have the highest IDO activity. With induction, the kynurenine metabolite concentrations of kynurenic acid and quinolinic acid are increased. The effects of both compounds were determined on the serotonergic pathway. Although kynurenic acid produced no significant effect, quinolinic acid significantly reduced N-acetylserotonin and melatonin synthesis at concentrations of lOJLM and 100 JLM respectively. Many authors have implicated oxygen derived species as causative agents in the important neurodegenerative disorders such as Parkinson's and Huntington's disease. Increased radical generation and lipid peroxidation have been suggested to be responsible for the toxic destruction of neurons, especially in the brain because of its high lipid content and oxygen demand. The brain is therefore vulnerable to oxidative attack. During inflammatory diseases, IDO is induced with a resultant increase in kynurenines. This study was also an attempt at determining the effect of kynurenines on lipid peroxidation. All metabolites of the kynurenine pathway were able to induce lipid peroxidation significantly. The antioxidative potential of various tryptophan analogues, viz. serotonin, melatonin and 6-methoxy-2-benzoxazolinone, was determined using quinolinic acid-induced lipid peroxidation. Serotonin, melatonin and 6-MBOA were able to significantly reduce quinolinic acid-induced lipid peroxidation.
- Full Text:
- Date Issued: 1998
- Authors: Antunes, Ana Paula Martins
- Date: 1998
- Subjects: Tryptophan -- Physiological effect , Antioxidants , Liver
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4010 , http://hdl.handle.net/10962/d1004070 , Tryptophan -- Physiological effect , Antioxidants , Liver
- Description: The amino acid, tryptophan, obtained through dietary means, is metabolised by the enzymes tryptophan 2,3-dioxygenase (TDO), indoleamine 2,3-dioxygenase (IDO) and tryptophan hydroxylase. All the enzymes have an effect on circulating tryptophan levels, especially TDO, since it is the major site of tryptophan catabolism in the liver and results in the production of kynurenine metabolites, viz. kynurenine, kynurenic acid, 3-hydroxyanthranilic acid and quinolinic acid. Extrahepatically, IDO is responsible for the synthesis of the kynurenine metabolites. Tryptophan 2,3-dioxygenase and IDO activity is increased by hormones or substrates such as tryptophan, and inflammation, in the case of IDO. Tryptophan availability for serotonin (5-HT) synthesis by the enzyme tryptophan hydroxylase is primarily dependent on TDO activity. A study was attempted in order to ascertain whether any of the endogenous metabolites of the kynurenine and serotonergic pathways would be able to inhibit TDO activity. Results showed that although the kynurenines had no effect, the indoleamines, except for the indoleacetic acids, were able to reduce TDO activity. 6-Methoxy-2-benzoxazolinone (6-MBOA), a structural analogue to melatonin, was the most potent inhibitor with a reduction in activity of 55 % compared with the control. The pineal gland in the rat brain has been shown to have the highest IDO activity. With induction, the kynurenine metabolite concentrations of kynurenic acid and quinolinic acid are increased. The effects of both compounds were determined on the serotonergic pathway. Although kynurenic acid produced no significant effect, quinolinic acid significantly reduced N-acetylserotonin and melatonin synthesis at concentrations of lOJLM and 100 JLM respectively. Many authors have implicated oxygen derived species as causative agents in the important neurodegenerative disorders such as Parkinson's and Huntington's disease. Increased radical generation and lipid peroxidation have been suggested to be responsible for the toxic destruction of neurons, especially in the brain because of its high lipid content and oxygen demand. The brain is therefore vulnerable to oxidative attack. During inflammatory diseases, IDO is induced with a resultant increase in kynurenines. This study was also an attempt at determining the effect of kynurenines on lipid peroxidation. All metabolites of the kynurenine pathway were able to induce lipid peroxidation significantly. The antioxidative potential of various tryptophan analogues, viz. serotonin, melatonin and 6-methoxy-2-benzoxazolinone, was determined using quinolinic acid-induced lipid peroxidation. Serotonin, melatonin and 6-MBOA were able to significantly reduce quinolinic acid-induced lipid peroxidation.
- Full Text:
- Date Issued: 1998
An Investigation into the feasibility of Human Facial Modeling
- Panagou, Sotcri, Bangay, Shaun D
- Authors: Panagou, Sotcri , Bangay, Shaun D
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432711 , vital:72894 , https://citeseerx.ist.psu.edu/document?repid=rep1ype=pdfoi=c305c27d16322208e0e6815ca261d61019a4cbd0
- Description: In this paper, virtual videoconferencing is investigated. The goal of the project is to develop a cheap, realistic yet real-time 3D face-modeling tool using a number of camera feeds. Bandwidth utilisation can then be minimised by transferring only the actual model (and subsequently, changes to the model) of the actor's face. Using a virtual reality system, reconstruction of a human face is performed and transmitted, thereby reducing bandwidth requirements. The modeling process is discussed, with results.
- Full Text:
- Date Issued: 1998
- Authors: Panagou, Sotcri , Bangay, Shaun D
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432711 , vital:72894 , https://citeseerx.ist.psu.edu/document?repid=rep1ype=pdfoi=c305c27d16322208e0e6815ca261d61019a4cbd0
- Description: In this paper, virtual videoconferencing is investigated. The goal of the project is to develop a cheap, realistic yet real-time 3D face-modeling tool using a number of camera feeds. Bandwidth utilisation can then be minimised by transferring only the actual model (and subsequently, changes to the model) of the actor's face. Using a virtual reality system, reconstruction of a human face is performed and transmitted, thereby reducing bandwidth requirements. The modeling process is discussed, with results.
- Full Text:
- Date Issued: 1998
Analysis of chromameter results obtained from corticosteroid-induced skin blanching. I. Manipulation of data
- Smith, Eric W, Haigh, John M, Walker, Roderick B
- Authors: Smith, Eric W , Haigh, John M , Walker, Roderick B
- Date: 1998
- Language: English
- Type: text , Article
- Identifier: vital:6424 , http://hdl.handle.net/10962/d1006559
- Description: Purpose. One of the unresolved issues in the FDA Guidance document for topical corticosteroid bioequivalence testing is the method of manipulation suggested for the chromameter data. The purpose of this study was to manipulate the instrumental data from a typical blanching study in a number of ways to investigate the appropriateness of these procedures for comparison with the subjective visually-assessed results. Methods. The human skin blanching assay methodology routinely practiced in our laboratories was utilised and the vasoconstriction produced by two corticosteroid formulations of different potency was assessed visually and instrumentally by use of a Minolta chromameter. The instrumental data were corrected for zero-time and unmedicated site readings. In addition, Euclidean distances were calculated using all data generated by the instrument. Results. Individually the a-, b- and L-scale chromameter values are imprecise and there is negligible vasoconstriction response recorded for the moderately potent formulation. Arithmetical manipulation of the data as suggested by the FDA does not appear to improve the quality of the data in any way. Euclidean distance analysis more closely resembles the visual data and appears to have better precision. Conclusions. It is clear that mathematical correction of chromameter data is unnecessary, especially since the instrumental data are extremely imprecise. Furthermore, the assessment of each individual chromameter index does not adequately characterise the blanching response profile. It is therefore suggested that Euclidean distance may be a better measure on which to base an analysis of bioequivalence than the truncated data set methodology currently suggested by the FDA.
- Full Text: false
- Date Issued: 1998
- Authors: Smith, Eric W , Haigh, John M , Walker, Roderick B
- Date: 1998
- Language: English
- Type: text , Article
- Identifier: vital:6424 , http://hdl.handle.net/10962/d1006559
- Description: Purpose. One of the unresolved issues in the FDA Guidance document for topical corticosteroid bioequivalence testing is the method of manipulation suggested for the chromameter data. The purpose of this study was to manipulate the instrumental data from a typical blanching study in a number of ways to investigate the appropriateness of these procedures for comparison with the subjective visually-assessed results. Methods. The human skin blanching assay methodology routinely practiced in our laboratories was utilised and the vasoconstriction produced by two corticosteroid formulations of different potency was assessed visually and instrumentally by use of a Minolta chromameter. The instrumental data were corrected for zero-time and unmedicated site readings. In addition, Euclidean distances were calculated using all data generated by the instrument. Results. Individually the a-, b- and L-scale chromameter values are imprecise and there is negligible vasoconstriction response recorded for the moderately potent formulation. Arithmetical manipulation of the data as suggested by the FDA does not appear to improve the quality of the data in any way. Euclidean distance analysis more closely resembles the visual data and appears to have better precision. Conclusions. It is clear that mathematical correction of chromameter data is unnecessary, especially since the instrumental data are extremely imprecise. Furthermore, the assessment of each individual chromameter index does not adequately characterise the blanching response profile. It is therefore suggested that Euclidean distance may be a better measure on which to base an analysis of bioequivalence than the truncated data set methodology currently suggested by the FDA.
- Full Text: false
- Date Issued: 1998
Analysis of macrolide antibiotics
- Kanfer, Isadore, Skinner, Michael F, Walker, Roderick B
- Authors: Kanfer, Isadore , Skinner, Michael F , Walker, Roderick B
- Date: 1998
- Language: English
- Type: Article , text
- Identifier: vital:7011 , http://hdl.handle.net/10962/d1008394 , http://www.sciencedirect.com/science/article/pii/S0021967398002763
- Description: The following macrolide antibiotics have been covered in this review: erythromycin and its related substances, azithromycin, clarithromycin, dirithromycin, roxithromycin, flurithromycin, josamycin, rokitamycin, kitasamycin, mycinamycin, mirosamycin, oleandomycin, rosaramicin, spiramycin and tylosin. The application of various thin-layer chromatography, paper chromatography, gas chromatography, high-performance liquid chromatography and capillary zone electrophoresis procedures for their analysis are described. These techniques have been applied to the separation and quantitative analysis of the macrolides in fermentation media, purity assessment of raw materials, assay of pharmaceutical dosage forms and the measurement of clinically useful macrolide antibiotics in biological samples such as blood, plasma, serum, urine and tissues. Data relating to the chromatographic behaviour of some macrolide antibiotics as well as the various detection methods used, such as bioautography, UV spectrophotometry, fluorometry, electrochemical detection, chemiluminescence and mass spectrometry techniques are also included.
- Full Text:
- Date Issued: 1998
- Authors: Kanfer, Isadore , Skinner, Michael F , Walker, Roderick B
- Date: 1998
- Language: English
- Type: Article , text
- Identifier: vital:7011 , http://hdl.handle.net/10962/d1008394 , http://www.sciencedirect.com/science/article/pii/S0021967398002763
- Description: The following macrolide antibiotics have been covered in this review: erythromycin and its related substances, azithromycin, clarithromycin, dirithromycin, roxithromycin, flurithromycin, josamycin, rokitamycin, kitasamycin, mycinamycin, mirosamycin, oleandomycin, rosaramicin, spiramycin and tylosin. The application of various thin-layer chromatography, paper chromatography, gas chromatography, high-performance liquid chromatography and capillary zone electrophoresis procedures for their analysis are described. These techniques have been applied to the separation and quantitative analysis of the macrolides in fermentation media, purity assessment of raw materials, assay of pharmaceutical dosage forms and the measurement of clinically useful macrolide antibiotics in biological samples such as blood, plasma, serum, urine and tissues. Data relating to the chromatographic behaviour of some macrolide antibiotics as well as the various detection methods used, such as bioautography, UV spectrophotometry, fluorometry, electrochemical detection, chemiluminescence and mass spectrometry techniques are also included.
- Full Text:
- Date Issued: 1998
Analysis of selected choral works by John Tavener with particular reference to the post-1977 works
- Authors: Imrie, Sally
- Date: 1998
- Subjects: Tavener, John Choral music
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:2642 , http://hdl.handle.net/10962/d1002307
- Description: This thesis deals with sacred choral music written by John Tavener, a British composer born in 1944. It touches briefly on the background of Tavener and his early works (i.e. from about 1960-1976) - two works from that period have been selected for analysis, Celtic Requiem and Nomine Jesu. The main body of the thesis is concerned with those works composed,.after 1977, which show the influence of the Orthodox Church and Byzantine hymnography on Tavener's stylistic development. The selected works from this period to be analysed are: Ode of St Andrew of Crete, Two Hymns to the Mother of God, Magnificat, Nunc Dimittis, The Uncreated Eros, Eonia and We Shall See Him As Heis.
- Full Text:
- Date Issued: 1998
- Authors: Imrie, Sally
- Date: 1998
- Subjects: Tavener, John Choral music
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:2642 , http://hdl.handle.net/10962/d1002307
- Description: This thesis deals with sacred choral music written by John Tavener, a British composer born in 1944. It touches briefly on the background of Tavener and his early works (i.e. from about 1960-1976) - two works from that period have been selected for analysis, Celtic Requiem and Nomine Jesu. The main body of the thesis is concerned with those works composed,.after 1977, which show the influence of the Orthodox Church and Byzantine hymnography on Tavener's stylistic development. The selected works from this period to be analysed are: Ode of St Andrew of Crete, Two Hymns to the Mother of God, Magnificat, Nunc Dimittis, The Uncreated Eros, Eonia and We Shall See Him As Heis.
- Full Text:
- Date Issued: 1998
Aspects of renormalisation in some quantum field theories
- Authors: Roy, Alan A
- Date: 1998
- Subjects: Quantum field theory , Renormalization group
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5400 , http://hdl.handle.net/10962/d1005214 , Quantum field theory , Renormalization group
- Description: Renormalisation is an important aspect of Quantum Field Theory. It is used to create physically meaningful theories and some major developments took place in the 1970's and onwards. We consider Renormalisation in its application to the theories of ψ⁴ , Quantum Electrodynamics, Quantum Chromodynamics and the Background Field Method. Feynman diagrams are used to illustrate many of the concepts.
- Full Text:
- Date Issued: 1998
- Authors: Roy, Alan A
- Date: 1998
- Subjects: Quantum field theory , Renormalization group
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5400 , http://hdl.handle.net/10962/d1005214 , Quantum field theory , Renormalization group
- Description: Renormalisation is an important aspect of Quantum Field Theory. It is used to create physically meaningful theories and some major developments took place in the 1970's and onwards. We consider Renormalisation in its application to the theories of ψ⁴ , Quantum Electrodynamics, Quantum Chromodynamics and the Background Field Method. Feynman diagrams are used to illustrate many of the concepts.
- Full Text:
- Date Issued: 1998
Aspects of the biology of the doublesash butterflyfish, Chaetodon marleyi (Pisces: Chaetodontidae)
- Authors: Vine, Niall Gordon
- Date: 1998
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21103 , http://hdl.handle.net/10962/6396
- Description: The doublesash butterflyfish, Chaetodon marleyi, indigenous to South Africa, is popular amongst marine aquarists. To provide a basis for the management of the species and assess its suitability for aquaculture, aspects of its biology were investigated. Specimens were collected between February 1996 and November 1997 from localities along the eastern Cape coastline of South Africa and from specimens in the RUSI fish collection. The dentition of C.marleyi is typical of non-coraline, benthic invertebrate feeding chaetodontids. The teeth are long, inwardly hooked and spatulate which allow easy grasping and manipulation of the prey. Stomach content analysis showed that the species fed predominantly on the tentacles of terebellid polychaetes with other polychaetes, crustaceans, hydro ids and ascideans contributing to the remainder of the diet. Juveniles had a larger volume of terebellid tentacles compared to adults which preyed more upon other polychaetes. The proximate composition (64.25% protein, 4.76% fat, 4.84% carbohydrate and 24.3 kJ/g total energy content) of the terebellid tentacles was determined suggesting a high energetic requirement of the fish or maximisation of feeding profit rates.
- Full Text:
- Date Issued: 1998
- Authors: Vine, Niall Gordon
- Date: 1998
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21103 , http://hdl.handle.net/10962/6396
- Description: The doublesash butterflyfish, Chaetodon marleyi, indigenous to South Africa, is popular amongst marine aquarists. To provide a basis for the management of the species and assess its suitability for aquaculture, aspects of its biology were investigated. Specimens were collected between February 1996 and November 1997 from localities along the eastern Cape coastline of South Africa and from specimens in the RUSI fish collection. The dentition of C.marleyi is typical of non-coraline, benthic invertebrate feeding chaetodontids. The teeth are long, inwardly hooked and spatulate which allow easy grasping and manipulation of the prey. Stomach content analysis showed that the species fed predominantly on the tentacles of terebellid polychaetes with other polychaetes, crustaceans, hydro ids and ascideans contributing to the remainder of the diet. Juveniles had a larger volume of terebellid tentacles compared to adults which preyed more upon other polychaetes. The proximate composition (64.25% protein, 4.76% fat, 4.84% carbohydrate and 24.3 kJ/g total energy content) of the terebellid tentacles was determined suggesting a high energetic requirement of the fish or maximisation of feeding profit rates.
- Full Text:
- Date Issued: 1998
Aspects of the ecology and reproductive biology of three cichlid fish species of Southern Lake Malombe (Malawi)
- Authors: Jambo, Collins Mayeso
- Date: 1998
- Subjects: Cichlids -- Africa, East -- Lake Malombe , Cichlids -- Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5224 , http://hdl.handle.net/10962/d1005067 , Cichlids -- Africa, East -- Lake Malombe , Cichlids -- Ecology
- Description: The three major species Lethrinops ''pinkhead'', Otopharynx argyrosoma "red" and Copadichromis. cf virginalis which used to dominate the catches (by weight) of Lake Malombe in the past decade were investigated. In order to make rational recommendations regarding size and boundary of the existing sanctuary area (lightly fished), distribution and abundance, population structure and reproductive biology of the three species were related to habitat types of the southern part of the lake (south western side and south eastern side). Analysis of catch composition showed that species richness was higher in the south eastern side than in the south western side of the lake. Rare species such as Labeo mesops and Opsaridium microiepis were observed in the south eastern side and there was visual absence of such species in the south western side of the lake. The overall fish abundance was significantly greater in the south eastern side than in the south western side of the lake. In the south eastern side, the catch per unit effort (CPUE) was twice that of the south western side (P< 0.05). Seasonal fluctuations in CPUE were also prominent, with the highest peak occurring during September-October period. However, there was an indication of weak relationship among CPUE, phytoplankton biomass, temperature and water depth. The length-weight relationships revealed that growth of the three species closely followed the cubic law for isometric growth in both sides of the lake. Differences in regression coefficients between sides were not significant (ttest, P>0.05). The length-frequency distribution analysis revealed that the three species had the same growth rate regardless of habitat type. However, females grew faster than males. An investigation of reproductive biology showed that the three species have low fecundity and they are asynchronous spawners, with a breeding peak during August and September period. Furthermore, the length-fecundity relationships for L. ''pinkhead'', and 0. argyrosoma "red" indicated that fecundity was more closely related to length in the south eastern side than in the south western side. Based on the above characteristics of L. ''pinkhead'', 0. argyrosoma "red" and C. cf virginalis, and the substrate types, it was strongly suggested that the existing sanctuary (lightly fished) in the south eastern side of the lake could immediately be enlarged to conserve the fish stocks, favourable substratum and aquatic animals that may be of tourists concern.
- Full Text:
- Date Issued: 1998
- Authors: Jambo, Collins Mayeso
- Date: 1998
- Subjects: Cichlids -- Africa, East -- Lake Malombe , Cichlids -- Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5224 , http://hdl.handle.net/10962/d1005067 , Cichlids -- Africa, East -- Lake Malombe , Cichlids -- Ecology
- Description: The three major species Lethrinops ''pinkhead'', Otopharynx argyrosoma "red" and Copadichromis. cf virginalis which used to dominate the catches (by weight) of Lake Malombe in the past decade were investigated. In order to make rational recommendations regarding size and boundary of the existing sanctuary area (lightly fished), distribution and abundance, population structure and reproductive biology of the three species were related to habitat types of the southern part of the lake (south western side and south eastern side). Analysis of catch composition showed that species richness was higher in the south eastern side than in the south western side of the lake. Rare species such as Labeo mesops and Opsaridium microiepis were observed in the south eastern side and there was visual absence of such species in the south western side of the lake. The overall fish abundance was significantly greater in the south eastern side than in the south western side of the lake. In the south eastern side, the catch per unit effort (CPUE) was twice that of the south western side (P< 0.05). Seasonal fluctuations in CPUE were also prominent, with the highest peak occurring during September-October period. However, there was an indication of weak relationship among CPUE, phytoplankton biomass, temperature and water depth. The length-weight relationships revealed that growth of the three species closely followed the cubic law for isometric growth in both sides of the lake. Differences in regression coefficients between sides were not significant (ttest, P>0.05). The length-frequency distribution analysis revealed that the three species had the same growth rate regardless of habitat type. However, females grew faster than males. An investigation of reproductive biology showed that the three species have low fecundity and they are asynchronous spawners, with a breeding peak during August and September period. Furthermore, the length-fecundity relationships for L. ''pinkhead'', and 0. argyrosoma "red" indicated that fecundity was more closely related to length in the south eastern side than in the south western side. Based on the above characteristics of L. ''pinkhead'', 0. argyrosoma "red" and C. cf virginalis, and the substrate types, it was strongly suggested that the existing sanctuary (lightly fished) in the south eastern side of the lake could immediately be enlarged to conserve the fish stocks, favourable substratum and aquatic animals that may be of tourists concern.
- Full Text:
- Date Issued: 1998
Asymmetric induction in reactions of chiral carboxylic esters and silyl enol ethers
- Authors: Evans, Melanie Daryl
- Date: 1998
- Subjects: Ethers -- Synthesis Esters -- Synthesis Chirality Asymmetric synthesis Organic compounds -- Synthesis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4409 , http://hdl.handle.net/10962/d1006762
- Description: Several camphor and pinane derivatives have been synthesised and evaluated for use as chiral auxiliaries in asymmetric synthesis. Various blocking groups have been attached to the camphor skeleton in attempts to improve stereofacial selectivity; these include α-methoxybenzyl and xylyl groups, and novel stereoisomeric ketal moieties derived from meso- and (R,R)-(-)-2,3-butanediol. Benzylation reactions carried out on the lithium enolates of ester derivatives of the camphor-derived chiral auxiliaries afforded α-benzylated products in 5-60% diastereomeric excess. Stereochemical aspects have been explored using high resolution NMR, X-ray crystallographic and computer modelling techniques, and hydrolysis of selected α-benzylated products has permitted the diasteroselective bias to be confirmed. Opposite configurations at the new stereogenic centre are clearly favoured by the xylyl and ketal blocking groups - an observation rationalised in terms of the presence or absence of chelating potential in the blocking group. Baylis-Hillman reactions carried out on a series of specially prepared camphor-derived acrylic esters containing the ketal blocking group exhibited both low diastereoselectivities (0-30% d.e.) and very long reaction times. Chiral silyl enol ethers, synthesised using both pinane and camphor derivatives as chiral auxiliaries, showed up to 20% diastereomeric excess in MCPBA oxidation, alkylation and Mukaiyama reactions. Attempts to bring the prochiral centre in the silyl enol ether substrates closer to the chiral auxiliary, and thus improve the stereofacial selectivity, proved unsuccessful. The silyl enol ether derivatives, however, display interesting fragmentation patterns in their electron impact mass spectra, which were investigated using a combination of high resolution MS, comparative low resolution MS and metastable peak analysis.
- Full Text:
- Date Issued: 1998
- Authors: Evans, Melanie Daryl
- Date: 1998
- Subjects: Ethers -- Synthesis Esters -- Synthesis Chirality Asymmetric synthesis Organic compounds -- Synthesis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4409 , http://hdl.handle.net/10962/d1006762
- Description: Several camphor and pinane derivatives have been synthesised and evaluated for use as chiral auxiliaries in asymmetric synthesis. Various blocking groups have been attached to the camphor skeleton in attempts to improve stereofacial selectivity; these include α-methoxybenzyl and xylyl groups, and novel stereoisomeric ketal moieties derived from meso- and (R,R)-(-)-2,3-butanediol. Benzylation reactions carried out on the lithium enolates of ester derivatives of the camphor-derived chiral auxiliaries afforded α-benzylated products in 5-60% diastereomeric excess. Stereochemical aspects have been explored using high resolution NMR, X-ray crystallographic and computer modelling techniques, and hydrolysis of selected α-benzylated products has permitted the diasteroselective bias to be confirmed. Opposite configurations at the new stereogenic centre are clearly favoured by the xylyl and ketal blocking groups - an observation rationalised in terms of the presence or absence of chelating potential in the blocking group. Baylis-Hillman reactions carried out on a series of specially prepared camphor-derived acrylic esters containing the ketal blocking group exhibited both low diastereoselectivities (0-30% d.e.) and very long reaction times. Chiral silyl enol ethers, synthesised using both pinane and camphor derivatives as chiral auxiliaries, showed up to 20% diastereomeric excess in MCPBA oxidation, alkylation and Mukaiyama reactions. Attempts to bring the prochiral centre in the silyl enol ether substrates closer to the chiral auxiliary, and thus improve the stereofacial selectivity, proved unsuccessful. The silyl enol ether derivatives, however, display interesting fragmentation patterns in their electron impact mass spectra, which were investigated using a combination of high resolution MS, comparative low resolution MS and metastable peak analysis.
- Full Text:
- Date Issued: 1998
At play in the master's workshop: the experience of reading in the novels of Henry James
- Authors: Seddon, Deborah Ann
- Date: 1998
- Subjects: James, Henry, 1843-1916 -- Criticism and interpretation
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2278 , http://hdl.handle.net/10962/d1007451 , James, Henry, 1843-1916 -- Criticism and interpretation
- Description: James's belief that "it is art that makes life" is essential to his own literary technique and to the reading experience within and in relation to his novels. The thesis seeks to posit the notion of reading as a fundamental concern in Henry James's fiction. Drawing largely on the phenomenological and anthropological approaches to the reading process of Wolfgang Iser, this thesis examines the Jamesian text as a performative event involving author, reader and character in creative and interpretative narrational struggles. Iser uses "play" as an integral term to describe the dynamic between author-reader-text which produces a literary work of art. In James's fiction the doubling of the author/reader and reader/character role within the text crucially structures a narrative form which is itself an inquiry into the human use of fiction. The Iserian conception of the act of reading as an engagement with the "gaps" within the play-space of the literary text can elucidate James's structural and thematic use of such sites of indeterminacy to foreground the enlivening necessity of an indeterminate "felt life" within human narrative structures. What Maisie Knew highlights the most important rule in the game -- the necessity for the reader to create meaning from the indeterminate aspects of the text. The shared exercise for author-reader-character is the attempt to access the child's unformulated inner reality to ascertain what Maisie knows. In the section on The Portrait of a Lady Iser's notion of reading as an ideational activity aids an inquiry into the human use of mental fictive picturing to compose reality. The Ambassadors demonstrates the "anthropological" need for the particular mode of consciousness brought about by the literary text when we engage in a world as real as but different to our own. Strether is the reader's ambassador in this world and his interpretative activity mirrors the reader's quest. In The Golden Bowl the bewildering multiplicity of readings made possible by the indeterminate aspects of the literary text instigates a contest for narrative forms in which the chosen fictions of the readers/characters must be actively willed into existence.
- Full Text:
- Date Issued: 1998
- Authors: Seddon, Deborah Ann
- Date: 1998
- Subjects: James, Henry, 1843-1916 -- Criticism and interpretation
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2278 , http://hdl.handle.net/10962/d1007451 , James, Henry, 1843-1916 -- Criticism and interpretation
- Description: James's belief that "it is art that makes life" is essential to his own literary technique and to the reading experience within and in relation to his novels. The thesis seeks to posit the notion of reading as a fundamental concern in Henry James's fiction. Drawing largely on the phenomenological and anthropological approaches to the reading process of Wolfgang Iser, this thesis examines the Jamesian text as a performative event involving author, reader and character in creative and interpretative narrational struggles. Iser uses "play" as an integral term to describe the dynamic between author-reader-text which produces a literary work of art. In James's fiction the doubling of the author/reader and reader/character role within the text crucially structures a narrative form which is itself an inquiry into the human use of fiction. The Iserian conception of the act of reading as an engagement with the "gaps" within the play-space of the literary text can elucidate James's structural and thematic use of such sites of indeterminacy to foreground the enlivening necessity of an indeterminate "felt life" within human narrative structures. What Maisie Knew highlights the most important rule in the game -- the necessity for the reader to create meaning from the indeterminate aspects of the text. The shared exercise for author-reader-character is the attempt to access the child's unformulated inner reality to ascertain what Maisie knows. In the section on The Portrait of a Lady Iser's notion of reading as an ideational activity aids an inquiry into the human use of mental fictive picturing to compose reality. The Ambassadors demonstrates the "anthropological" need for the particular mode of consciousness brought about by the literary text when we engage in a world as real as but different to our own. Strether is the reader's ambassador in this world and his interpretative activity mirrors the reader's quest. In The Golden Bowl the bewildering multiplicity of readings made possible by the indeterminate aspects of the literary text instigates a contest for narrative forms in which the chosen fictions of the readers/characters must be actively willed into existence.
- Full Text:
- Date Issued: 1998
Barrier-free tourism in the natural environment for people with physical disabilities with specific reference to Eastern Cape facilities
- Authors: Chapman, Sally Lynn
- Date: 1998
- Subjects: People with disabilities -- Travel -- South Africa , People with disabilities -- Services for -- South Africa , Game reserves -- South Africa -- Eastern Cape , Trails -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:693 , http://hdl.handle.net/10962/d1006384 , People with disabilities -- Travel -- South Africa , People with disabilities -- Services for -- South Africa , Game reserves -- South Africa -- Eastern Cape , Trails -- South Africa -- Eastern Cape
- Description: Social workers are becoming increasingly involved in community projects, thus allowing them to reach more people. One of these areas involves the sensitising of society in the removal of barriers which prevent people with disabilities from living balanced and integrated lives. One aspect requiring particular attention is the natural environment which, until recently, has been neglected. In order to increase the knowledge of the researcher in the field of environmental accessibility, twenty six people with physical disabilities were interviewed to ascertain which factors they saw as important and relevant when assessing the natural environment. Their ideas were incorporated into practical assessments of a game reserve and a possible hiking trail for people with disabilities. As it is of vital importance to include the consumers in studies of this nature, selected people with varying abilities and disabilities assisted in these "hands on" studies. Qualitative interviews were also conducted on the owners of facilities who were in the process of making their facilities accessible. This allowed the researcher and selected people with disabilities to evaluate positive and negative experiences, thus adding to their knowledge base and building capacity for people with disabilities
- Full Text:
- Date Issued: 1998
- Authors: Chapman, Sally Lynn
- Date: 1998
- Subjects: People with disabilities -- Travel -- South Africa , People with disabilities -- Services for -- South Africa , Game reserves -- South Africa -- Eastern Cape , Trails -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:693 , http://hdl.handle.net/10962/d1006384 , People with disabilities -- Travel -- South Africa , People with disabilities -- Services for -- South Africa , Game reserves -- South Africa -- Eastern Cape , Trails -- South Africa -- Eastern Cape
- Description: Social workers are becoming increasingly involved in community projects, thus allowing them to reach more people. One of these areas involves the sensitising of society in the removal of barriers which prevent people with disabilities from living balanced and integrated lives. One aspect requiring particular attention is the natural environment which, until recently, has been neglected. In order to increase the knowledge of the researcher in the field of environmental accessibility, twenty six people with physical disabilities were interviewed to ascertain which factors they saw as important and relevant when assessing the natural environment. Their ideas were incorporated into practical assessments of a game reserve and a possible hiking trail for people with disabilities. As it is of vital importance to include the consumers in studies of this nature, selected people with varying abilities and disabilities assisted in these "hands on" studies. Qualitative interviews were also conducted on the owners of facilities who were in the process of making their facilities accessible. This allowed the researcher and selected people with disabilities to evaluate positive and negative experiences, thus adding to their knowledge base and building capacity for people with disabilities
- Full Text:
- Date Issued: 1998
Baylis-Hillman derived benzopyrans and related systems : a synthetic and mechanistic study
- Authors: Robinson, Ross Stuart
- Date: 1998
- Subjects: Benzopyrans Coumarins Heterocyclic compounds -- Derivatives
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4429 , http://hdl.handle.net/10962/d1007193
- Description: The Baylis-Hillman reaction between substituted salicylaldehydes and various acrylate species has been shown to afford complex reaction mixtures, careful chromatography of which has led to the isolation of an extensive range of novel compounds. One- and two-dimensional NMR spectroscopic, mass spectrometric and X-ray crystallographic analysis of these compounds have permitted identification of no less than eight general classes of chromene and coumarin derivatives. The formation of the various product types is attributed to cascades of successive reactions stemming, in each case, from a Baylis-Hillman product as the common intermediate. The mechanistic sequence involved in the formation of the various chromene and coumarin derivatives have been elucidated by examining isolated or specifically prepared compounds as putative reaction intermediates. Conjugate addition and acyl or allylic substitution by various nucleophiles appear to be common processes in the formation of the chromene and coumarin derivatives, and studies focussing on these processes have been undertaken. Reactions of Baylis-Hillman adducts have been carried out, using oxygen, sulfur and nitrogen nucleophiles, in order to explore stereoselectivity and regioselectivity trends. The results show that the reactions proceed with a very high degree of regioselectivity, affording conjugate addition rather than acyl substitution products. The diastereoselectivity observed for the addition products, however was typically low. A kinetic study to explore the regioselectivity of the reaction between various Baylis-Hillman derived halogeno esters and the nucleophile, methyl 3-oxobutanolate enloate, in two different base-solvent systems at high dilution was also undertaken. The reactions were monitored by ¹H NMR spectroscopy, and the results revealed that the reaction kinetics are more complex than originally anticipated. A mechanistic rationalisation is offered which is consistent with both the kinetic data and the observed regioselectivity trends.
- Full Text:
- Date Issued: 1998
- Authors: Robinson, Ross Stuart
- Date: 1998
- Subjects: Benzopyrans Coumarins Heterocyclic compounds -- Derivatives
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4429 , http://hdl.handle.net/10962/d1007193
- Description: The Baylis-Hillman reaction between substituted salicylaldehydes and various acrylate species has been shown to afford complex reaction mixtures, careful chromatography of which has led to the isolation of an extensive range of novel compounds. One- and two-dimensional NMR spectroscopic, mass spectrometric and X-ray crystallographic analysis of these compounds have permitted identification of no less than eight general classes of chromene and coumarin derivatives. The formation of the various product types is attributed to cascades of successive reactions stemming, in each case, from a Baylis-Hillman product as the common intermediate. The mechanistic sequence involved in the formation of the various chromene and coumarin derivatives have been elucidated by examining isolated or specifically prepared compounds as putative reaction intermediates. Conjugate addition and acyl or allylic substitution by various nucleophiles appear to be common processes in the formation of the chromene and coumarin derivatives, and studies focussing on these processes have been undertaken. Reactions of Baylis-Hillman adducts have been carried out, using oxygen, sulfur and nitrogen nucleophiles, in order to explore stereoselectivity and regioselectivity trends. The results show that the reactions proceed with a very high degree of regioselectivity, affording conjugate addition rather than acyl substitution products. The diastereoselectivity observed for the addition products, however was typically low. A kinetic study to explore the regioselectivity of the reaction between various Baylis-Hillman derived halogeno esters and the nucleophile, methyl 3-oxobutanolate enloate, in two different base-solvent systems at high dilution was also undertaken. The reactions were monitored by ¹H NMR spectroscopy, and the results revealed that the reaction kinetics are more complex than originally anticipated. A mechanistic rationalisation is offered which is consistent with both the kinetic data and the observed regioselectivity trends.
- Full Text:
- Date Issued: 1998
Bioequivalence testing of topical dermatological formulations, the gap between science and legislation
- Schwarb, Fabian P, Smith, Eric W, Haigh, John M, Surber, Christian
- Authors: Schwarb, Fabian P , Smith, Eric W , Haigh, John M , Surber, Christian
- Date: 1998
- Language: English
- Type: Conference paper
- Identifier: vital:6341 , http://hdl.handle.net/10962/d1006608
- Description: Bioavailability concerns for topical dermatological products are complex and it is especially difficult to determine the bioequivalence of similar topical formulations. Since only small amounts of drug dispersed in an appropriate vehicle are applied to the skin, the amount of drug that actually reaches the systemic circulation is often too small to be easily quantified. Additionally, it can be argued that the relevance of any serum/plasma concentration-time curve of a topical agent is questionable, since the curve reflects the amount of drug after the active moiety has left the site of action. For some topical drugs e.g., topical corticosteroids, it is possible to perform a pharmacodynamic bioassay to obtain acceptable bioequivalence data. In this case, the intensity of the side effect of blanching (vasoconstriction) in the skin caused by topical corticosteroids can be measured. The response is directly proportional to the clinical efficacy, and the skin blanching assay has proved to be a reliable procedure for the determination of topical corticosteroid bioavailability. Recently, we had sight of the results of a topical bioequivalence study, which was conducted for the registration of a new generic corticosteroid cream formulation. In this trial the new formulation was compared to two equivalent product from the local market and bioequivalence was demonstrated by the investigators for all three products. These results were examined with interest as the respective reference products have been used repeatedly as standard formulations in our laboratory. However, one of these reference formulations has consistently shown superior bioavailability in our trials, but was not demonstrated to be superior in the study results examined. In the present publication an overview of topical bioequivalence testing in general is given and the difficulties occurring in practice, for topical corticosteroid formulations in particular, are demonstrated.
- Full Text:
- Date Issued: 1998
- Authors: Schwarb, Fabian P , Smith, Eric W , Haigh, John M , Surber, Christian
- Date: 1998
- Language: English
- Type: Conference paper
- Identifier: vital:6341 , http://hdl.handle.net/10962/d1006608
- Description: Bioavailability concerns for topical dermatological products are complex and it is especially difficult to determine the bioequivalence of similar topical formulations. Since only small amounts of drug dispersed in an appropriate vehicle are applied to the skin, the amount of drug that actually reaches the systemic circulation is often too small to be easily quantified. Additionally, it can be argued that the relevance of any serum/plasma concentration-time curve of a topical agent is questionable, since the curve reflects the amount of drug after the active moiety has left the site of action. For some topical drugs e.g., topical corticosteroids, it is possible to perform a pharmacodynamic bioassay to obtain acceptable bioequivalence data. In this case, the intensity of the side effect of blanching (vasoconstriction) in the skin caused by topical corticosteroids can be measured. The response is directly proportional to the clinical efficacy, and the skin blanching assay has proved to be a reliable procedure for the determination of topical corticosteroid bioavailability. Recently, we had sight of the results of a topical bioequivalence study, which was conducted for the registration of a new generic corticosteroid cream formulation. In this trial the new formulation was compared to two equivalent product from the local market and bioequivalence was demonstrated by the investigators for all three products. These results were examined with interest as the respective reference products have been used repeatedly as standard formulations in our laboratory. However, one of these reference formulations has consistently shown superior bioavailability in our trials, but was not demonstrated to be superior in the study results examined. In the present publication an overview of topical bioequivalence testing in general is given and the difficulties occurring in practice, for topical corticosteroid formulations in particular, are demonstrated.
- Full Text:
- Date Issued: 1998
Biology and management of the Cape gurnard, Chelidonichthys capensis (Order Scorpaeniformes, Family Triglidae) in South Africa
- Authors: McPhail, Amanda Sue
- Date: 1998
- Subjects: Scorpaeniformes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5236 , http://hdl.handle.net/10962/d1005079 , Scorpaeniformes
- Description: The South African demersal trawl fishery, as with most trawl-directed fisheries worldwide, has a substantial bycatch component. With increasing commercial emphasis being placed on retained bycatch, an urgent need has arisen to investigate these species. In the past the bycatch component has received little research or management attention. Members of the gurnard family Triglidae make up up to 2.4 % of the South African hake-directed demersal catch and are thus considered an important bycatch species. The catch history and biology, including population structure, reproduction, feeding, age, growth and mortality, of the Cape gurnard, Chelidonichthys capensis, sampled from the Agulhas Bank, South Africa, were thus investigated. Males (mean TL = 366mm) were significantly smaller than females (mean TL = 411mm). The sex ratio was close to parity, males being more dominant in commercial trawls and less dominant in research trawls. Gonad maturation and gonadosomatic indices showed this species to have an extended spawning period with peaks in reproductive activity during September, January and April. First approximations of size at 50 % maturity were similar for females (349mm TL) and males (348mm TL) but differed significantly in terms of age (3.6 years and 4.6 years respectively). Otolith growth marks were validated as annuli using marginal zone analysis. The maximum age estimated was 16 years for a female of 675mm TL and recruitment to the commercial fishery was estimated as taking place in the fifth year of growth for both males and females. Gut content analysis showed C. capensis to be an opportunistic feeder preying preferentially on the benthic crustaceans Goneplax angulata and Mursia cristimanus. Landings from the commercial linefishery were insignificant whilst those for the commercial trawl fishery ranged from 500 tonnes to 3250 tonnes between 1984 to 1995, and indicated that this species forms an important component of the South African trawl fishery bycatch. A first approximation of fishing mortality (0.36 year⁻¹) for the inshore commercial trawl fishery was higher than that of natural mortality (0.25 year⁻¹) suggesting some fishing pressure on this species on the Agulhas Bank. However this fishing mortality value was significantly less than that for F₀·₁ (4.78 year⁻¹) that was estimated using a yield-per-recruit model.
- Full Text:
- Date Issued: 1998
- Authors: McPhail, Amanda Sue
- Date: 1998
- Subjects: Scorpaeniformes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5236 , http://hdl.handle.net/10962/d1005079 , Scorpaeniformes
- Description: The South African demersal trawl fishery, as with most trawl-directed fisheries worldwide, has a substantial bycatch component. With increasing commercial emphasis being placed on retained bycatch, an urgent need has arisen to investigate these species. In the past the bycatch component has received little research or management attention. Members of the gurnard family Triglidae make up up to 2.4 % of the South African hake-directed demersal catch and are thus considered an important bycatch species. The catch history and biology, including population structure, reproduction, feeding, age, growth and mortality, of the Cape gurnard, Chelidonichthys capensis, sampled from the Agulhas Bank, South Africa, were thus investigated. Males (mean TL = 366mm) were significantly smaller than females (mean TL = 411mm). The sex ratio was close to parity, males being more dominant in commercial trawls and less dominant in research trawls. Gonad maturation and gonadosomatic indices showed this species to have an extended spawning period with peaks in reproductive activity during September, January and April. First approximations of size at 50 % maturity were similar for females (349mm TL) and males (348mm TL) but differed significantly in terms of age (3.6 years and 4.6 years respectively). Otolith growth marks were validated as annuli using marginal zone analysis. The maximum age estimated was 16 years for a female of 675mm TL and recruitment to the commercial fishery was estimated as taking place in the fifth year of growth for both males and females. Gut content analysis showed C. capensis to be an opportunistic feeder preying preferentially on the benthic crustaceans Goneplax angulata and Mursia cristimanus. Landings from the commercial linefishery were insignificant whilst those for the commercial trawl fishery ranged from 500 tonnes to 3250 tonnes between 1984 to 1995, and indicated that this species forms an important component of the South African trawl fishery bycatch. A first approximation of fishing mortality (0.36 year⁻¹) for the inshore commercial trawl fishery was higher than that of natural mortality (0.25 year⁻¹) suggesting some fishing pressure on this species on the Agulhas Bank. However this fishing mortality value was significantly less than that for F₀·₁ (4.78 year⁻¹) that was estimated using a yield-per-recruit model.
- Full Text:
- Date Issued: 1998