Accuracy and reproducibility of the multiple-reading skin blanching assay
- Authors: Smith, Eric W , Meyer, Eric , Haigh, John M
- Date: 1992
- Language: English
- Type: Book chapter
- Identifier: vital:6439 , http://hdl.handle.net/10962/d1006625
- Full Text:
- Date Issued: 1992
Algal biotechnology and the beneficiation of saline effluent wastes
- Authors: Rose, P D (Peter Dale)
- Date: 1992
- Subjects: Algae -- Biotechnology , Algae culture , Tanneries -- Waste disposal
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4135 , http://hdl.handle.net/10962/d1015967
- Description: Saline deterioration in the South African public water system has been documented and disposal of brine wastes has been identified as part of the problem. The broad aim of this research programme was to undertake an initial technical study to evaluate the feasibility of integrating algal biotechnology into a disposal function for these wastes. A demonstration of utility in the form of products and waste treatment could produce a beneficiation of saline effluents and provide incentives necessary to deal with the disposal issue. The study attempted to demonstrate a synthesis between the two main thrusts in algal biotechnology that have produced large-scale practical applications - stable, predictable algal production in saline media and the cost effective High Rate Oxidation Ponding (HROP) process for incorporating algal production into a waste treatment function. Tannery organic saline effluents and the biotechnology of Dunaliella salina culture producing β- carotene were chosen as paradigms for the study. 1. The alga was shown to grow in certain tannery effluents producing enhanced biomass yields compared to defined inorganic medium cultivation. The potential for amino acid or protein supplementation of defmed culture media was noted. 2. A reduction in organic load simultaneous with the growth of D.salina was recorded in laboratory-scale simulations of the HROP process. Rates similar to the fresh water HROP equivalent were demonstrated. 3. These results suggested the uptake and storage of organic nitrogen by D.salina. The consequent inhibition of β-carotene accumulation by the organism presented a potentially insurmountable obstacle to the feasibility of β-carotene production in this medium. Uptake and release of organic compounds, previously demonstrated in phytoplankton and other micro-algae, was confirmed in this study for D.salina. The evidence acquired indicated the internalization of both glycine and bovine serum albumin. An ultrastructural study demonstrated mechanisms by which this process might occur. 4. The release of substantial quantities of glycerol was shown. A mechanism whereby D. salina may use this to regulate ammonia availability via control of its associated bacterial population was observed. Glycerol release was identified as presenting an application in treating refractory organic wastes, such as secondary sewage sludges, by elevating C:N ratios. This could demonstrate a significant utility for brine waste impoundments. 5. A multistage production process was proposed to deal with the problem of β-carotene inhibition by separation of the growth and metabolite accumulation functions into separate unit operations. It was shown in this study that the stress of nitrogen deficiency combined with high salinity provides for effectiveβ-carotene accumulation under the conditions of low illumination that pertain in dense cultures. Subjected to these conditions effluent-grown cells show delayed but unimpaired {j-carotene accumulation. 6. A role for the plant hormone abscisic acid in mediating the stress response was demonstrated in D.salina. Fluorescence induction studies suggested the presence of a signalling process forming part of a sensitivity control mechanism. Stress induction of β-carotene accumulation could occur through four clearly defined stages. Potential was identified for using this response as a physiological probe for monitoring and regulating the stress induction process. 7. The multistage processing concept requires effective algal cell separation technology. The use of cross-flow ultrafiltration and diafiltration with a polyethersulfone tubular membrane system was demonstrated as an effective process for the recovery and washing of D. salina. Cell concentrates were produced in a viable form. 8. Process designs incorporating the findings of the research programme are presented demonstrating how effluent and organic waste treatment functions may be combined with the production of D.salina and its products. Application of the multi-stage processing concept to β-carotene production in a defined medium process was identified as offering a potential four-fold yield enhancement. This could have a significant impact on a high cost, marginal algal biotechnology process. Aspects of novelty have been claimed in provisional patents applications. A provisional demonstration of the feasibility of D.salina production in tannery effluent indicates that algal biotechnology may provide a utility for, and hence the beneficiation of saline effluent wastes.
- Full Text:
- Date Issued: 1992
An assessment of a new personality measure of authoritarianism in the South African context
- Authors: Léger, Paul
- Date: 1992
- Subjects: Authoritarianism (Personality trait) -- Research , Authoritarianism -- Research -- South Africa , Psychological tests -- Research , Personality tests -- Research
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3007 , http://hdl.handle.net/10962/d1002516 , Authoritarianism (Personality trait) -- Research , Authoritarianism -- Research -- South Africa , Psychological tests -- Research , Personality tests -- Research
- Description: The aim of the research was to assess the psychometric properties of Altemeyer's (1981) Right-Wing Authoritarianism scale (RWA scale)- developed in response to identified methodological weaknesses in personality measures of authoritarianism to date - within a South African setting. A modified version of the 24-item attitudinal scale, together with a demographic questionnaire was administered to a white and black sample of South African university students. Subsequent psychometric analysis of the data indicated that the scale was a significantly less powerful measure of authoritarianism in a cross-cultural context, than originally hoped for. Not only did the analysis show an absence of psychometric equivalence but revealed substantial problems within the content of the scale itself. An ensuing discussion of these findings situated the debate within a broader theoretical context. It was argued that the RWA scale, and its underpinning conceptualization, although possibly comprising a methodological refinement over existing measures of authoritarianism, did not constitute grounds for a viable approach to research on authoritarianism in the South African context. It was concluded that a model of authoritarianism resting on the assumptions of positivistic psychology, inevitably failed to account for the social and political dynamics of a changing society. As a socially relevant enterprise, it was suggested that the debate on authoritarianism be extended beyond the confines of individualistic psychology and research priority directed instead to the crucial role of societal factors giving rise to the individual manifestation of the phenomenon.
- Full Text:
- Date Issued: 1992
An evaluation of the use of computers in a South African primary school
- Authors: Mostert, Orla
- Date: 1992
- Subjects: Education, Elementary -- South Africa -- Computer-assisted instruction Computer-assisted instruction -- South Africa Educational technology -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1528 , http://hdl.handle.net/10962/d1003410
- Description: The introduction of the computer into the educational arena is unique as pressure for its inclusion has come not from educationalists, but from public demand based on the conviction that exposure to computers is an essential ingredient of modern education. This has resulted in computers being added to school curricula before there has been careful research into its educational implications, making huge demands on teachers involved in the innovation. South African primary schools involved in computer education have followed international trends in their adoption of computers, initially perceiving computer education as a separate subject added on to the present curriculum. However, changing trends in computer use internationally are now beginning to reflect educators' changing perceptions of the nature of primary education, and educators are calling for the use of computers to be integrated into the curriculum rather than being seen as an area of study in themselves. This investigation attempts to outline general trends and perceptions of computer use in a South African primary school. Despite a high level of computer usage at the observed school, the computer was seen by teachers, in the main, as an extra subject, and has not yet led to any significant changes in teaching styles and methods. The research suggests that two main issues need to be resolved before computer education in primary schools reflects the present paradigm shift towards learner-centered educational practices. Firstly, there is a need to rethink the delivery of the curriculum towards one which promotes a greater degree of problem solving and decision making on the part of the learner. Secondly, it would appear that teachers need to be made more aware of this trend.
- Full Text:
- Date Issued: 1992
An examination of the sonnets of E.E. Cummings
- Authors: Hughes, Jeremy Francis
- Date: 1992
- Subjects: Cummings, E. E. (Edward Estlin), 1894-1962 -- Criticism and interpretation Sonnets, English -- Criticism and interpretation
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2244 , http://hdl.handle.net/10962/d1002287
- Description: This dissertation examines E. E. Cummings's writings in the sonnet genre and in those genres to which the sonnet is related in various ways. Its fundamental point is that, despite the surface impression of poetic iconoclasm for which Cummings has a popular reputation, in choosing to write sonnets he engages in a traditional literary practice. He does this because his purpose is always to be an artist, as defined by the Aesthetic movement which influenced him. In order to argue his embracing of a traditional artistic role, the theory of genres espoused by Alastair Fowler in his book, Kinds of Literature, is used. Chapter 1 of the thesis comprises general introductory material, both to the range of Aesthetic ideas to which Cummings subscribed, and to Fowler's theory of genres. Several key generic kinds are also described. The second chapter makes use of two of these generic models, the sonnet sequence and the silva, as a way of examining Cummings's deployment of the sonnet within the larger context of his poetry collections. It is a survey of the structure of the anthologies he compiled from Tulips & Chimneys (1922) to 95 Poems (1958). The third chapter explores the three sonnet modes which Cummings first identifies and names when compiling the manuscript of Tulips & Chimneys, and continues to use in his collections up to and including is 5 (1926). Chapter 4 shows how certain themes and concerns from these early sonnets are altered and synthesised as Cummings matures from an aesthete to a Romantic poet. Sonnets from his later books are taken to be representative of three central kinds in all of his work after is 5. Chapters 3 and 4 proceed by means of relatively close readings of individual sonnets. This practice fulfils a double role: it penetrates the apparent obscurity of the more difficult poems, and it attempts to preserve the integrity of individual poems which exemplify different generic tendencies in Cummings's work. One of Cummings's reasons for writing sonnets is that the form favours the achievement of what Wordsworth calls "a feeling of intense unity". In undertaking close readings of a few sonnets I have attempted to preserve that feeling.
- Full Text:
- Date Issued: 1992
An examination of the suitability of some contemporary South African fiction for readers in the post-developmental reading stage
- Authors: Cole, Lorna
- Date: 1992
- Subjects: Children's literature, South African -- History and criticism Children -- Books and reading -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1530 , http://hdl.handle.net/10962/d1003412
- Description: Adverse criticism regarding the quantity and quality of children's books in South Africa appear in such respected sources as The Oxford Companion to Children's Literature and The Companion to South African English Literature, the authors of which are of the opinion that South African children are dependent solely upon Eurocentric literature for their reading material. In recent years however, local publishers have attempted to redress this imbalance by offering prizes for unpublished works. These prizes have acted as incentives for aspiring writers, many of whom have had novels published specifically for children in the post-developmental reading stage. This study critically examines some of these prizewinning works of fantasy and contemporary realism, in an effort to gauge their literary worth within the context of accepted criteria for judging children's literature. Accolades from adults are not however a guarantee that the prizewinning books will be received with equal acclaim by the children for whom they are written. For this reason, five children in the post-developmental reading stage were asked to pass their opinions and non-literary judgments on the books. Although the critical evaluation of the indigenous works proves them to be eminently worthy of the prizes which they received on publication, the children did not rate them as highly as certain imported works. The works of fantasy by Marguerite Poland rated poorly in terms of their popularity despite the fact that the children said that in a non-circumscribed context, they choose fantasy in preference to contemporary realism. Within the context of the indigenous literature which they read for this study though, they preferred the works of contemporary realism as they were able to identify with particular aspects of the novels. Indigenous literature for children in the post-developmental reading stage is a comparatively new phenomenon which needs to be nurtured if it is to attain any lasting status. The onus rests upon the teachers of literature and librarians to introduce the literature and make the books more accessible to young readers. Publishers need perhaps to engage the views and opinions of the audience for whom the books are written in an effort to publish books which, without in any way detracting from their literary worth, will deal with subjects favoured by young readers.
- Full Text:
- Date Issued: 1992
An exploratory field study into schoolgirl pregnancies, with emphasis on the role the school can play in their prevention
- Authors: Kooverjee, Ishwar
- Date: 1992
- Subjects: Teenage pregnancy -- South Africa Sex instruction -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1537 , http://hdl.handle.net/10962/d1003419
- Description: This piece of research explores the problem of schoolgirl pregnancies and suggests a role which the school might play in their prevention. Concern over the growing number of unplanned pregnancies under the age of eighteen years at the author's school, culminated in the .present study. Experts on the subject often perceive the problem to be self-defeating to the young girls, medically contra-indicated and socially disruptive. The purpose of this investigation was to determine attitudes towards the description of the problem, to identify causative factors predisposing to pregnancy, and to obtain views on how the school can reconcile efforts to address the problem. The relevant research data was obtained through a comprehensive 64 item attitudinal and knowledge-base questionnaire which was administered to a sample of 187 subjects. The sample comprised seven different occupational groups namely, senior schoolgirls, parents of senior schoolgirls, ex-schoolgirl primigravidae, parents of ex-schoolgirl primigravidae, school teachers, members of the clergy and various health care professionals. The appendices contain full statistical tables as well as full responses to the open-ended essay based on the research questionnaire so that the reader is free to check the reasonableness of the conclusions drawn. In the final chapter the author provides a brief summary of findings, offers justification why the teaching of sex education should be a priority in public schools, and makes recommendations, in the main, for the inclusion of school-based sex education as a component of Guidance in terms of rationale and implementation. In addition, suggestions are made with regard to school policy formulation and networking with parents and other community resources. Finally, a choice of four current model programmes for sex education are proposed in an effort to improve and build upon existing programmes in the present South African curriculum. It is the author's belief that this investigation may contribute to course design and perhaps provide hypotheses for more specific studies in the future.
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- Date Issued: 1992
An investigation into the use of weather type models in the teaching of South African climatology at senior secondary school level
- Authors: Schürmann, Leon
- Date: 1992
- Subjects: Climatology -- Study and teaching (Secondary) , Geography -- Study and teaching (Secondary)
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2009 , http://hdl.handle.net/10962/d1015948
- Description: The synoptic chart encodes climatological and meteorological information in a highly abstract manner. The pupil's level of cognitive development, the nature of the syllabus and the teaching strategies employed by the geography teacher influence the pupil's conceptualisation of information. The synoptic chart is a valuable tool for consolidating the content of the S.A climatology syllabus. Recent research has established that climatology-meteorology, and especially synoptic chart reading and interpretation, is difficult for the concrete thinker. These pupils find difficulty in visualising the weather processes and systems. Provided that they are simple and clear, models are useful teaching devices that integrate and generalise information in a manner that is easily retrievable. The intention of the author is to provide weather type models and other supporting strategies and aids as a means to improve the senior secondary pupil's assimilation of southern African climatological-meteorological information. This model-based approach is tested in the classroom using an action research framework to judge its efficacy. Conclusions are drawn and recommendations are made.
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- Date Issued: 1992
Analyzing communication flow and process placement in Linda programs on transputers
- Authors: De-Heer-Menlah, Frederick Kofi
- Date: 1992 , 2012-11-28
- Subjects: LINDA (Computer system) , Transputers , Parallel programming (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4675 , http://hdl.handle.net/10962/d1006698 , LINDA (Computer system) , Transputers , Parallel programming (Computer science)
- Description: With the evolution of parallel and distributed systems, users from diverse disciplines have looked to these systems as a solution to their ever increasing needs for computer processing resources. Because parallel processing systems currently require a high level of expertise to program, many researchers are investing effort into developing programming approaches which hide some of the difficulties of parallel programming from users. Linda, is one such parallel paradigm, which is intuitive to use, and which provides a high level decoupling between distributable components of parallel programs. In Linda, efficiency becomes a concern of the implementation rather than of the programmer. There is a substantial overhead in implementing Linda, an inherently shared memory model on a distributed system. This thesis describes the compile-time analysis of tuple space interactions which reduce the run-time matching costs, and permits the distributon of the tuple space data. A language independent module which partitions the tuple space data and suggests appropriate storage schemes for the partitions so as to optimise Linda operations is presented. The thesis also discusses hiding the network topology from the user by automatically allocating Linda processes and tuple space partitons to nodes in the network of transputers. This is done by introducing a fast placement algorithm developed for Linda. , KMBT_223
- Full Text:
- Date Issued: 1992
Applicability of the SERVQUAL instrument under South African conditions : an assessment of four situations
- Authors: Pitt, Leyland Frederick
- Date: 1992
- Subjects: SERVQUAL instrument , Customer service , Measurement , Service quality , South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1160 , http://hdl.handle.net/10962/d1001627
- Description: On-going research in recent years has shown quality of product and service, as perceived by customer, relative to competition, to be the single most important factor contributing to organizational well-being. Quality of product and service also presents one of the most significant opportunities for corporate differentiation. A major requirement for the successful management of quality is therefore effective measurement. In the case of physical goods, progress has been made over a long period. However, in the case of services, real advances have only occurred within the past decade. The importance of service quality is also highlighted by the fact that most businesses today are losing customers due to its inadequacy, rather than poor products. Indeed, from the customer's point of view, services and products probably do not exist in a dichotomy, but, rather, along a spectrum. Therefore, the measurement of service quality is critical, not only in traditional service organizations, but in manufacturing situations as well. The development of the SERVQUAL questionnaire in 1988, offered researchers, perhaps for the first time, an apparently reliable and valid instrument for the measurement of service quality. However, to date the instrument has not been subjected to rigorous testing for reliability and validity in South Africa, across a range of service organizations, within a typology. In this study, the SERVQUAL instrument was used to measure service quality across a range of firms within the Larsson-Bowen contingency framework, under South African conditions. Its main objectives were to assess its reliability and validity in these circumstances. It was found that SERVQUAL performed well across all organizations within the Larsson-Bowen framework, under South African conditions, with regard to reliability, convergent and nomological validity. Its construct validity proved to be less sound, and it was not found to possess discriminant validity. It is suggested that this is less attributable to South African circumstances than to the nature of the organizations. In cases of low diversity of demand, the instrument appears to capture the essence of service quality less effectively. Means of overcoming this in future studies are suggested, as well as other directions for research in the area of service quality measurement
- Full Text:
- Date Issued: 1992
Aspects of fuzzy spaces with special reference to cardinality, dimension, and order-homomorphisms
- Authors: Lubczonok, Pawel
- Date: 1992
- Subjects: Fuzzy sets Topological spaces
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5399 , http://hdl.handle.net/10962/d1005213
- Description: Aspects of fuzzy vector spaces and fuzzy groups are investigated, including linear independence, basis, dimension, group order, finitely generated groups and cyclic groups. It was necessary to consider cardinality of fuzzy sets and related issues, which included a question of ways in which to define functions between fuzzy sets. Among the results proved, are the additivity property of dimension for fuzzy vector spaces, Lagrange's Theorem for fuzzy groups ( the existing version of this theorem does not take fuzziness into account at all), a compactness property of finitely generated fuzzy groups and an extension of an earlier result on the order-homomorphisms. An open question is posed with regard to the existence of a basis for an arbitrary fuzzy vector space.
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- Date Issued: 1992
Aspects of the biology of two inshore sparid fishes (Diplodus sargus capensis and Diplodus cervinus hottentotus) off the south-east coast of South Africa
- Authors: Mann, Bruce Quintin
- Date: 1992
- Subjects: Sparidae , Diplodus
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5222 , http://hdl.handle.net/10962/d1005065 , Sparidae , Diplodus
- Description: The blacktail, Diplodus sargus capensis and the zebra, Diplodus cervinus hottentotus, sparid fishes endemic to South Africa, are important components of the recreational shore-fishery. To provide a basis for the management of these fish, aspects of the biology of both species were investigated in the Tsitsikamma National Park (TNP). In particular, the role of the TNP was evaluated as a management option for the conservation of both species. Examination of stomach contents showed that juveniles of both species fed predominantly on amphipods, polychaetes and harpacticoid copepods. Adult !h. sargus were omnivorous and fed opportunistically on a wide variety of reef associated invertebrates and algae including echinoids, polychaetes, anthozoans, ascidians and rhodophytes. The diet of adult D. cervinus was more specialized with a preference shown for polychaetes and amphipods. Seasonal differences were apparent in the diets of both species where considerably more amphipods were consumed in winter than in summer. Feeding requirements of both species were reflected in their habitat preferences. Visual underwater assessment revealed that both species were most abundant on turbulent inshore reefs (1-10m). !h. sargus were observed over a wide variety of reef associated habitats. In the literature they have also been recorded in the surf zone of sandy beaches and in the lower reaches of estuaries. !h. cervinus, on the other hand, were more specific in their habitat requirements and were observed in greatest abundance on inshore reefs, often in close association with caves or overhangs. A comparison between the relative abundance and size structure of both species in the TNP with that of an exploited area immediately adjacent to the reserve, showed no significant differences. This was attributed to the low level of exploitation by rock-and-surf anglers occurring in the exploited study area, as well as the possibility of seeding of eggs and larvae, or emigration of adults from the TNP. An investigation of the reproductive biology of both fish showed that !h. sargus had an extended summer spawning season while in !h. cervi nus it was more restricted. Detailed histological examination of gonadal development showed that !h. sarqus were dygynous with partial protandry occuring in the male population. ~ cervinus were shown to be rudimentary hermaphrodites. Size at 50% maturity in ~ sargus and ~ cervinus was determined at 225 and 285mm fork length respectively, corresponding to ages of 4 and 6 years. An age and growth study based on the examination of sectioned otoliths showed that both species were slow growing capable of reaching ages in excess of 20 years. Growth in ~ sargus and ~ cervinus was described by the von Bertalanffy growth equations: L(t) = 309.44(1-e-0 . 247[t+l. 048 l) and L(t) = 396.85(1-e-0.146[t+2.148J) respectively. Life history characteristics of D. sargus and D. cervinus including slow growth, late maturation and occupation of a localised, demersal habitat showed that both species were vulnerable to the effects of over-fishing. Due to the present increase in the number of participants and the decrease in catch per unit effort in the recreational shore-fishery, more stringent management recommendations were proposed to ensure the adequate protection of both species. These included an increased minimum size limit and a decreased bag limit for both species. Based on the residency shown by both species and their high relative abundance in the TNP, marine reserves were considered to be a valuable addition to the suite of management options available for the conservation of these species . In this respect the reserve provided both protection for the spawner stock as well as the potential to seed adjacent areas.
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- Date Issued: 1992
Assessment of the profit sharing schemes
- Authors: NUM
- Date: 1992
- Subjects: NUM
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/149616 , vital:38869
- Description: In 1991 and 1992, the NUM accepted basic wage Increases on the gold mines that were far below the annual Inflation rate because of the crisis in the industry. The priority of the union was to preserve employment. But this left the door wide open for rich mines (like Kloof, Elandsrand and Vaal Reefs) to hide behind the low increases that are set in the Chamber negotiations at levels that Freegold, Buffelsfontein and marginal mines can live with. The NUM decided that workers need a way of adding more money onto their wages If the mines can afford to pay more.
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- Date Issued: 1992
Benthic assemblage structure, and the feeding biology of sixteen macroinvertebrate taxa from the Buffalo River, Eastern Cape, South Africa
- Authors: Palmer, Carolyn Gay
- Date: 1992
- Subjects: Aquatic invertebrates -- South Africa -- Eastern Cape Benthos -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5646 , http://hdl.handle.net/10962/d1005328
- Description: The River continuum concept (RCC) (Vannote et al. 1980) attempted to provide a unifying theory of river function. The Functional Feeding Group (FFG) concept (Cummins 1973, 1974) became a major component of the RCC. The FFG concept provides testable hypotheses about the changes in proportions of FFGs along a downstream gradient in a river, in response to the changing nature of food resources. The following short-comings of the FFG concept have been identified: 1) the variability of macroinvertebrate feeding, 2) problems with gut analysis as a method for assigning taxa to FFGs, and 3) inconsistent criteria defining FFGs. The objective of this study was to investigate the macroinvertebrate fauna of the Buffalo River in order to assess the applicability of aspects of the RCC and the FFG concept. The specific aims of the study were: 1) to describe the distribution of macroinvertebrate assemblages in the Buffalo River; 2) to clarify aspects of the FFG concept listed above; 3) to establish whether selected taxa could be assigned to FFGs; 4) to assess whether the proportions of different FFGs in successive reaches of a southern African river conformed to the predictions of the RCC; and 5) to test whether a functional classification is a useful alternative to a taxonomic classification. Macroinvertebrates were collected seasonally from a variety of biotopes at three sites, one each in the upper, middle and lower reaches. Riffles were sampled in summer at 16 sites. Over 100 taxa were identified and an hierarchical classification was prepared using two-way indicator species analysis. Invertebrate assemblages in the narrow headwater stream were taxonomically distinct from those of the middle/lower reaches and were not positively associated with subjectively identified biotopes. Biotopes were characterised by distinct assemblages in the wider middle/lower reaches. Sixteen abundant taxa whose feeding had not been previously investigated were selected for feeding studies, four from the headwaters and 12 from the middle/lower reaches. Methods used included gut content analysis, behavioural observations, food choice experiments and morphological studies using scanning electron microscopy. Three aspects of the functional feeding group concept were clarified. 1) Dietary variability was assessed using gut contents as an index of diet. The gut contents of both early (small) and late (large) instar larvae of all 16 taxa collected from different sites and biotopes, and in different seasons were compared using a multifactor analysis of variance. For all taxa the most consistently significant differences in gut contents were between large and small larvae. These were due to differences in the amount of material in the gut and in varying amounts of rarer dietary items. Dietary variability did not prevent taxa from being assigned to FFGs. 2) Gut content analysis satisfactorily provided basic information about the feeding biology of taxa but proved to be an inadequate single method for positively assigning taxa to FFGs. 3) Before taxa could be assigned to FFGs the definitions for some FFG categories had to be described clearly. It is suggested that the term shredder be based on the observation of shredding and a predominance of leaf fragments in the foregut. The presence of algae was not diagnostic of scrapers and a morphological basis is suggested. A morphological basis for the brusher FFG is described for the first time. All 16 taxa were assigned to FFGs. Three headwater taxa were shredders ((Goerodes caffrariae (Lepidostomatidae), Dyschimus ensifer (Pisulidae), Afronemoura spp. (Notonemouridae)) and one was a collector:brusher (Adenophlebia auriculata (Leptophlebiidae). These results were consistent with RCC predictions. All 12 of the taxa from the middle/lower reaches were filterers or collectors and this result was also consistent with RCC predictions. The Hydropsychidae, Cheumtopsyche afra and Macrostemum capense, were passive net filterers; Neurocaenis reticulatus (Tricorythidae) was a passive setal filterer; Caenidae sp. Band Pseudocloeon maculosum (Baetidae) were active filterers; caenidae sp. A, and the Baetidae, Baetis harrisoni, Centroptilum excisum and Cloeon africanum, were collector: gatherers; the Leptophlebiidae, Choroterpes elegans and Choroterpes nigrescens, were collector:brushers; and Afronurus harrisoni (Heptageniidae) was a scraper. Gut content analyses alone were insufficient to assign taxa to FFGs, but when augmented by morphological and/or behavioural data, taxa could be assigned to FFGs with confidence. In all cases the FFG designation referred to the most frequent style of feeding. N. reticulatus, A. harrisoni and A. auriculata were particularly flexible in their feeding behaviour. A functional classification of macro invertebrates in the Buffalo River was compared with a taxonomic classification. In both cases similar groups were identified, but their taxonomic and functional descriptions yielded different information. It is suggested that functional and taxonomic classifications should be viewed as complementary rather than alternative options.
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- Date Issued: 1992
Biopharmaceutics and pharmacokinetics of the macrolide antibiotic Josamycin
- Authors: Skinner, Michael Fredrick
- Date: 1992
- Subjects: Antibiotics -- Bioavailability , Antibiotics -- Pharmacokinetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3791 , http://hdl.handle.net/10962/d1003269
- Description: The investigations detailed herein have been conducted to address various aspects of the biopharmaceutics and pharmacokinetics of josamycin which to-date, have received little or no attention in the literature. Areas of investigation have included the selective determination of josamycin in serum and urine samples, the stability of josamycin in stored biological samples, intrinsic dissolution rates, solubility, acid and alkali stability and bioavailability and pharmacokinetics after dosing with a solution, powder and tablets. High performance liquid chromatography (HPLC) was used as the main analytical tool throughout these studies and proved to be highly versatile for the determination of josamycin in a number of different media. HPLC analysis afforded simple yet accurate determination of josamycin in samples from dissolution, solubility, tablet content and stability studies. Furthermore, the specificity afforded by HPLC was particularly useful for the separation of josamycin from degradation products formed in acid and alkali media. Since metabolites of josamycin are microbiologically active, microbiological assays do not determine the concentration solely of josamycin. An analytical method capable of the selective determination of josamycin in serum and urine samples is therefore required for the procurement of reliable bioavailability and pharmacokinetic data. HPLC affords this selectivity and a method for the selective determination of josamycin in serum and urine was successfully developed. The assay was simple yet precise, accurate and sensitive. Furthermore, it was well suited to the determination of josamycin in a large number of biological samples. Its success was largely due to the use of a solid phase extraction step using C₁₈ extraction columns, with a highly specific wash sequence followed by a phase separation step after elution from the extraction column. Chromatography was performed on a C₁₈ reversed-phase analytical column with UV detection of josamycin and internal standard at 231 nm and at 204 nm respectively using a programmable multi-wavelength detector. Only slight modification of the assay described should enable the selective determination of the metabolites of josamycin. This assay, therefore, lays the groundwork for future investigations into the pharmacokinetics of these metabolites. The re-usability of extraction columns was assessed in an attempt to reduce the cost of sample analysis. It was found that extraction columns could be used twice for the extraction of serum samples and up to four times for the extraction of urine samples. The difference between the re-usability of extraction columns for serum and urine samples was ascribed to various differences in the composition of the sample matrix. The stability of josamycin in stored serum and urine samples was also assessed.
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- Date Issued: 1992
Chemical and spectroscopic studies of chromone derivatives
- Authors: Davidson, Deborah Nicole
- Date: 1992
- Subjects: Chromatophores Plant pigments Asthma -- Treatment -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4420 , http://hdl.handle.net/10962/d1006857
- Description: Various chromone derivatives have been used in asthma therapy, and their biological activity is apparently related to certain chemical features which include conformation and acidity. In the present study, substituent effects on conformation and acidity have been explored in chromone systems with potential biological activity. A range of variously substituted symmetrical chromone-2-carboxamides (including a series of N,N-dimethylchromone-2-carboxamides) have been prepared via chromone-2-carboxylic acids, which, in turn, were prepared from the corresponding o-hydroxyacetophenones. The N,N-dimethylchromone-2-carboxamides were prepared by reacting the appropriate chromone-2-carbonyl chlorides with dimethylammonium chloride in pyridine, in an approach which resolved various problems encountered in the preparation of these compounds. Substituent effects on the conformation of chromone-2-carboxamides have been explored using dynamic NMR spectroscopy, and the observed splitting of the N-alkyl signals has been attributed to slow site-exchange of the N-alkyl substituents. Dynamic NMR frequency separations and coalescence temperatures have been used to calculate rotational energy barriers, and substituent effects on these rotational energy barriers have been analysed. The possible implication of ring-opening of chromones in chromone pharmacology has also been examined. A range of 3-(2-hydroxybenzoyl)acrylamides has been prepared via the dimethylamine-mediated ring-opening of N,N-dimethylchromone-2-carboxamides and the E-double-bond configuration of the ring-opened products has been unambiguously established by single crystal analysis of the parent system. The configuration and conformation of the crystal structure of the parent system have been shown, using IR and NMR spectroscopic, and molecular graphics techniques, to be maintained in solution and to characterise the whole series. ¹H and ¹³C NMR spectroscopy have also been used to study the dimethylamine-mediated ring-opening of disodium cromoglycate. The kinetics of the dimethylamine-mediated ring-opening of N,N-dimethylchromone-2-carboxamides have been studied using UV spectroscopy. These reactions have been shown to follow third-order kinetics overall and a mechanism accommodating the observed third-order kinetics has been proposed. Substituent effects have been further investigated by the potentiometric determination of the pKa (pK [subscript a]) values for a series of chromone-2-carboxylic acids. The relationship between acidity and the observed rate constants has been explored and has verified that the observed rate constants are sensitive to the influence of meta-substituents on the stability of the phenoxide ion "leaving group" rather than C-2 electrophilicity.
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- Date Issued: 1992
Complete regularity and related concepts in L-uniform spaces
- Authors: Harnett, Rait Sicklen
- Date: 1992
- Subjects: Uniform spaces , Mathematics -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5403 , http://hdl.handle.net/10962/d1005217 , Uniform spaces , Mathematics -- Research
- Description: L will denote a completely distributive lattice with an order reversing involution. The concept of an L-uniform space is introduced. An extension theorem concerning L-uniformly continuous functions is proved. A characterisation of L-uniformizability, involving L-complete regularity is given. With respect to L--completely regular spaces it is shown that the topological modification of an L-completely regular space is completely regular. Furthermore it is shown that the topologically generated L-topology of a completely regular space is L-completely regular.
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- Date Issued: 1992
Dance and sexual politics some implications of the status of women in selected dance forms
- Authors: Poona, Sobhna Keshavelal
- Date: 1992
- Subjects: Dance -- Social aspects , Sex discrimination against women
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2145 , http://hdl.handle.net/10962/d1002377 , Dance -- Social aspects , Sex discrimination against women
- Description: This thesis explores, from a feminist perspective, some implications on the status of women in selected dance forms, and addresses the perceptions of women as 'inferior' and 'subordinate'. One of the intentions behind the work was, indeed, to challenge prevailing perceptions and create an awareness of sexism, capitalism and patriarchy, especially for the uncritical and uninformed who have become its victims. Part 1 offers an analysis of the premises upon which social, political and economic inequality are founded and consolidated, with specific reference to sexual inequality and sexual prejudice. Utilising a Marxist-feminist and semiotic approach, the machinations of the traditional mass media are linked to negative imaging of the female body in support of the sexist, patriarchal, capitalist male manipulator, who benefits from women's subordinate social status. Part 2 addresses the issue of sexual politics, and the implications for dance research and performance. The researcher offers a descriptive analysis of four specific dance forms, which serve to highlight the socialisation and educational processes that shape our perceptions and instruct our lives. A set of questionnaires was sent to fourteen autonomous dance institutions, including those attached to national performing arts councils. The thesis concludes with a summary of the results of the questionnaires that were distributed amongst female dancers, dance students and choreographers. The researcher questions our culture's preoccupation with the female body image, and posits the urgent need for an assessment of this situation, and an education which will create a better understanding and a more harmonious climate for development.
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- Date Issued: 1992
Developing a problem solving approach to primary mathematics teaching: a case study
- Authors: Naidoo, Anandhavelli
- Date: 1992
- Subjects: Mathematics -- Study and teaching (Elementary) Problem solving -- Study and teaching (Elementary)
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1493 , http://hdl.handle.net/10962/d1003374
- Description: According to recent research a focus in teaching mathematics to children is the development of problem solving abilities. Problem solving means the process of applying mathematical knowledge and skills to unfamiliar situations. A case study was done using a problem solving approach to the learning and teaching of mathematics with a sample of teachers registered at the Umlazi College For Further Education. These teachers were familiar with the traditional approach of teaching mathematics through drill and practice methods. The new syllabus that is to be implemented emphasises a problem solving approach to the teaching of mathematics. This study set out to implement a problem solving approach with primary school mathematics teachers so that they would be someway prepared for the innovations of the new syllabus. Workshops were conducted using an action research approach with discourse and practice leading to reconstruction with improvements. Early theorists like Piaget and Bruner offered ways of understanding children's learning, to help the teacher develop his teaching. Dienes introduced an element of play and Dewey spoke of the importance of experience. Dienes and Dewey show the first positive signs of recognising the importance of social interaction in the learning situation. Social interaction lays emphasis on language and discussion in the mathematics classroom. A social constructivist model of teaching and learning was used for the research. This research includes a study of the established ideas on developing a problem solving approach to mathematics teaching. These ideas were incorporated into the workshops that the group of teachers attended. During the workshops teachers were gradually exposed to the essence of problem solving techniques through much group discussion and doing practical exercises, which they could then implement in their classes. The teachers reported back at each subsequent workshop. A non-participant observer evaluated the development at the workshops. The workshops' success was evident from the change in the teachers' attitudes and behaviour as well as their feedback of what transpired in the classroom. They reported on the change in their roles as information suppliers to facilitators where the thinking process was focused on, rather than the importance of a correct answer. In the workshops the teachers themselves moved from passive listeners to active participants. It would appear from this preliminary investigation that through using a problem solving approach in workshops, inservice teachers can benefit constructively from this approach and will attempt to use it in their own teaching.
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- Date Issued: 1992
Domestic strategies of rural Transkeian women
- Authors: Cloete, Laura
- Date: 1992
- Subjects: Rural families -- South Africa -- Transkei Women -- South Africa -- Transkei Women -- South Africa Sex role -- South Africa -- Transkei Rural women -- South Africa -- Transkei Transkei (South Africa) -- Social conditions Transkei (South Africa) -- Rural conditions Transkei (South Africa) -- Economic conditions
- Language: English
- Type: Book , Text
- Identifier: http://hdl.handle.net/10962/2014 , vital:20247 , ISBN 0868102342
- Description: This research, originally undertaken as part of a B.A.(Honours) Degree in Anthropology, has several aims. Firstly, it aims to reveal the various community options available to women in rural Transkei for coping with their domestic activities in the face of the large-scale absence of men. It will analyse the rationale behind the choices and their consequences for the women’s workload. Secondly, this will illuminate gender and generational roles and attitudes of community members, present and absent, in the community. The focus, in this case, will be predominantly on women, however. Thirdly, and finally, this research will analyse the relationships of power between men and women, and between adults and children by examining the various influences, such as religion and education, which constrain and coerce their behaviour and attitudes. From this, we should be left with an illuminating picture of the forces under which women operate in rural Transkei; and with some insight into their behaviour and attitudes, their beliefs and aspirations and into their lives. , Digitised by Rhodes University Library on behalf of the Institute of Social and Economic Research (ISER)
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- Date Issued: 1992