Showing items 401 - 420 of 453

Your selections:

The structure and function of the gametes of the striped field mouse (Rhabdomys pumilio)

  • Authors: Tinney, Gregory Michael
  • Date: 2000
  • Subjects: Gametes , Microtus , Mice
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5774 , http://hdl.handle.net/10962/d1005462 , Gametes , Microtus , Mice
  • Description: This study was initiated in an attempt toadd the four-striped field mouse (Rhabdomys pumilio) to the small group of mammals that are used to study and develop assisted reproductive technologies. To accomplish this, a complete knowledge of both the male and female gametes was necessary, as well as a repeatable and successful IVF protocol. The gametes of the field mouse, both the falciformspermand the mature oocytes, were shown to be similar in several respects to those of many other rodent species. The induction of both the capacitated state and the acrosome reaction in the sperm were readily achieved. The success of retrieving mature oocytes was very low, with the rare occurrence of polar bodies within ovulated oocytes. The difficulties with oocytes was either related to the lack of a regular oestrous cycle, or to the hormonal regime used to induce superovulation. Although several protocols were used to accomplish superovulation in this species, it was seldom achieved. In in vitro fertilization trials, sperm were found to attach to both the cumulus oophorus and the zona pellucida of the oocytes. However, fertilization was never accomplished. This failure to achieve fertilization was probably related to the immaturity of the oocytes. Without further studies on Rhabdomys pumilio and further attempts at accomplishing in vitro fertilization, it would seem that this species would not easily be introduced as an animalmodelfor assisted reproduction.
  • Full Text:
  • Date Issued: 2000

The structure and microbiology of floating sulphide oxidising biofilms

  • Authors: Gilfillan, Joanne Criseyde
  • Date: 2000
  • Subjects: Biofilms , Sulfides
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:3903 , http://hdl.handle.net/10962/d1003962 , Biofilms , Sulfides
  • Description: Floating sulphur biofilms are observed as surface layers in numerous aquatic sulphide-rich environments, and apparently play an important role in the cycling of sulphur in its various oxidation states. In addition to the conversion of sulphide to sulphur and/or sulphate species, it has been suspected that subsequent reduction back to sulphide may occur within the floating sulphur biofi1m in organic-rich environments. The use of sulphur biofilms for the harvesting of elemental sulphur from wastewater treatment systems has also been suggested. There is, however, little documented information in the literature on the structure of floating sulphur biofilms, or the microbial species responsible for their occurrence. In this study, floating sulphur biofilms were generated in a continuous flow baflle reactor and their structure was examined using scanning electron microscopy. It was found that they occur as layered structures with morphologically distinct bacterial forms present in different layers of the biofilm. The biofilpl structure was also found to be dynamic, with structural changes observed as feed conditions were altered. An enriched culture derived from the biofi1m demonstrated rates of sulphide oxidation comparable to values reported in the literature for liquid culture systems. The microbiology of the biofi1m was studied using traditional plate culture techniques and analysis ofrRNA genes. Identification of plate culture isolates as representatives of the biofi1m community proved to be limited, leading to a PeR-based cloning approach. The majority of the organisms present in the sulphur biofi1m were classified as species in the genus ~eudomonas, and a number of other bacterial species whose sulphide oxidising capacity has been noted previously. Surprisingly, only 2% of the clone library consisted of Thiobacillus spp., and no sulphate reducing bacteria were identified in the biofilm at all. These results indicate that in organic sulphide-rich environments facultative chemolithoheterotrophic bacterial forms predominate in floating sulphur biofilms, and that the complete biological cycling of sulphur may not occur in these systems.
  • Full Text:
  • Date Issued: 2000

The universtiy in a developing free society : challenges to autonomy and academic freedom

  • Authors: Makgoba, M W
  • Date: 2000
  • Subjects: Academic Freedom -- South Africa Universities and colleges -- South Africa Equality Liberty Education, Higher -- Political aspects -- South Africa Education and state -- South Africa Education, Higher -- South Africa
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/684 , vital:19981
  • Description: The real point of democratic reform, what I have been calling institutional reform, is not just to change the complexion of researchers, teachers and students, nor just to change the location of research and teaching, to be truly meaning- fill, reform has to lead to a change in the orientation of these activities. Let me take a hypothetical example, one where you succeed in adding more black and female faces to the research and leaching establishment and even to shifting the location of that establishment mainly to historically black universities - say your most advanced medical research facilities come to be located at the University of Fort Hare, with researchers mainly black and female, but the facility is still oriented to proton beam research for special types of cancer, away from the public health needs of the people - what will you have achieved? I dare say you would then have joined the ranks of independent Africa. The key issue will still remain not addressed: who should centres of research and learning serve and how? This is why I think the real challenge for all of us, whether south or north of the Limpopo, whether black or brown, yellow or white, is to begin thinking of how to root African universities in African soil.
  • Full Text:
  • Date Issued: 2000

The use of and trade in indigenous edible fruits in the Bushbuckridge savanna region, South Africa

  • Authors: Shackleton, Charlie M , Dzerefos, C M , Shackleton, Sheona E , Mathabela, F R
  • Date: 2000
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/182396 , vital:43826 , xlink:href="https://doi.org/10.1080/03670244.2000.9991616"
  • Description: The use, processing, cultivation and trading of indigenous edible fruits was recorded across a rainfall gradient in the Mpumalanga lowveld. Three transects, each consisting of one village in a relatively high rainfall zone, one village in a low rainfall zone, and one intermediate, were sampled by means of 20 households per village. Nearly all households made use of indigenous edible fruits to some extent, with households in the wettest region using the greatest diversity of fruits. The duration of availability of selected species was increased through drying, storing and processing the raw fruits for later consumption. Such activities were more common in the drier regions relative to the wetter villages. Just less than half the respondents maintained indigenous fruit trees within their homestead or arable fields, whereas more than 65% grew exotic commercial fruit species. Many respondents traded in edible fruits, but very few obtained a significant income in this way. Nonetheless, even casual trading provided vital supplementary income for low‐income households.
  • Full Text:
  • Date Issued: 2000

The use of indigenous macroinvertebrates and Daphnia pulex in acute toxicity testing

  • Authors: Everitt, Victoria Jane
  • Date: 2000
  • Subjects: Water -- Pollution -- Toxicology , Toxicity testing , Daphnia pulex
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5795 , http://hdl.handle.net/10962/d1005483
  • Description: Aquatic toxicology has been identified as a valuable tool in the identification and management of chemical pollution in aquatic ecosystems. Standardised methodologies for acute aquatic bioassays have been adopted from international agencies. As a result of these standard methods, the use of laboratory cultured organisms for toxicity testing has been more popular than that of indigenous field-caught organisms. Included in these adopted methods are those for the cultured crustacean Daphnia pUlex. D.pulex is adapted to living in standing water and the suitability of this species to determine toxic effects for South African riverine environments, which are largely flowing, has been questioned. Thus this thesis is a case-study ofthe use of D.pulex and indigenous site-specific macroinvertebrates as toxicity test organisms for setting acute water quality guidelines to protect aquatic ecosystems. The study highlights site-specific problems such as reference sites and organism identification. The acute tolerance of selected indigenous invertebrates was compared to that of D. pulex, using both a single-substance reference toxicant (zinc) and selected whole efiluents. The significance of source population and culture age as a potential source of biological variability between D.pulex cultures was also investigated. D.pulex cultures have been initiated in South Africa from females collected from a number of different local populations; also it is assumed that no genetic change (due to mutation) occurs within a D.pulex culture over time. In order to establish if source population and culture age are a source of biological variability between D.pulex experiments, the acute tolerJuce to zinc of two different D.pulex populations and three different generations within a population were compared. Due to experimental variability results were inconclusive, and differences in tolerance as a result of population difference or culture age could not be determined with confidence. The acute tolerance of D.pulex to a single reference chemical (zinc) and selected whole efiluents was compared to that of selected indigenous invertebrates. Acute 48 h D.pulex zinc tolerance (LC50 range: 0.22 - 0.60 mg/l Zn) was found to be more sensitive than acute 96 h tolerances shown by mayfly species A.fconurus peringueyi (Heptageniidae) (LC50: 17.42 mg/l Zn), Euthrauluselegans (Leptophlebiidae) (LC50: 0.98 mg/IZn), Ba~tidae (LC50: 0.94mg/IZn) and shrimp, Caradina nilotica (Atyidae) (LC50: 3.17 mg/l Zn). This result suggests that guidelines for zinc set using D.pulex will protect the selected indigenous invertebrates. Selected whole eftluents were not acutely toxic to either D.pulex or selected indigenous invertebrates. These experiments were used as a case study for method development regarding the comparative use of D.pulex and indigenous invertebrates in acute whole eftluent toxicity testing. Finally, it is recommended that a suite of indigenous organisms (e.g. macroinvertebrates, fish and algae), as well as laboratory cultured D.pulex, be used in the initial setting of guidelines and that D.pulex be used for routine compliance monitoring. It is futher recommended that a suite of available monitoring methods, such as chemical and biomonitoring methodologies, be used in conjuction with toxicity testing in water quality management.
  • Full Text:
  • Date Issued: 2000

The use of indigenous plants as food by a rural community in the Eastern Cape : an educational exploration

  • Authors: Shava, Soul
  • Date: 2000
  • Subjects: Plants, Edible -- South Africa -- Eastern Cape Wild plants, Edible -- South Africa -- Eastern Cape Human-plant relationships -- South Africa -- Eastern Cape Endemic plants -- South Africa
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1813 , http://hdl.handle.net/10962/d1003699
  • Description: Looking at the use of plants as food reflects how humankind has fashioned nature. There has been a significant change in production patterns from hunter-gathering through subsistence agriculture to technologically advanced commercial agriculture with a subsequent reduction in the diversity of plants used as food. A parallel trend in consumption patterns has occurred, from home-based food processing for subsistence through small- scale production to large-scale industrial processing and the commodification of food. The overall result of such trends is a narrowing of the food resource base and an increasing reliance on processed foods at the expense of traditional diets, accompanied by increasing diet-related health risks. This research is an ethnographic case study on the use of indigenous food plants by the community of Tuku A village in the Eastern Cape using interviews and observations as the main data collecting strategies. A nutritional analysis of some wild food plants was also carried out. An inventory of more than 70 food plant species was compiled, with the knowledge of such plants found among both the elderly and the youth. The incorporation of this knowledge into education systems is recommended. Of the wild food plants documented, some were non-indigenous indicating the dynamic nature of indigenous knowledge. Some wild spinach were left to grow amongst cultivated food plants, hinting at some form of ‘domestication’ in process. This observation together with the observation that wild fruit trees were selectively conserved highlights the possibility of the continued use of wild food contributing to conservation of botanical diversity. Community use of indigenous food was found to be diminishing. Stigmatisation of indigenous food plants, urbanisation, formal education, changes in lifestyle, and media were some of the factors possibly influencing this dietary shift. The community made links between diet and health, which correspond to modern scientific knowledge, with modern diet being lamented for ill health. The nutritional analysis revealed that wild food plants do contain essential dietary nutrients, an area recommended for further research.
  • Full Text:
  • Date Issued: 2000

The utilisation of Asolla filiculoides Lam. as a biofertiliser under dryland conditions

  • Authors: Kiguli, Lillian Nakibuuka
  • Date: 2000
  • Subjects: Asolla as fertilizer
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4206 , http://hdl.handle.net/10962/d1003775 , Asolla as fertilizer
  • Description: The response of wheat to soil fertilised with varying quantities of the water fern Azolla filiculoides was investigated. Experiments were conducted to differentiate between the effects of increased soil mineral status and water status. In the preliminary investigation, experiments were carried out in the greenhouse using potted wheat grown in sand with varying proportions of A. filiculoides that had been subjected tovarious pre-treatments. The pre-treatments were fresh, dry and heated A. filiculoides applied at 20%, 50% and 80% volume per 3000 ml. There were significant differences in the measured growth parameters between the plants grown in the various treatments. In addition, the grain yield of wheat plants varied with the different treatments. Results of the preliminary study showed that the addition of heated and dried A. filiculoides resulted in significantly better growth than the addition of fresh A. filiculoides in sand. For fresh biomass, grain weights, Leaf area ratio (LAR) and relative growth rate (RGR), the performance of dried A. filiculoides was as good as that of the heated A. filiculoides. Productivity of wheat in the heated treatments increased significantly with increasing proportion of A. filiculoides added to sand, while in dry treatments there were no significant increases in productivity in the preliminary study. This supported the hypothesis that A. filiculoides, a notorious water weed can be put to agricultural use under dryland conditions in poor nutrient soils. Further investigations using dried A. filiculoides in sand and topsoil showed that the use of the same amounts of the dried fern made no significant short term impact on topsoil grown winter wheat but significantly improved the productivity of wheat in sand. Results showed that the addition of dried 20% Azolla to sand improved the soil fertility to levels equalling the quality of the control topsoil, but the addition of 80% Azolla to sand led to significantly greater wheat productivity than all other treatments. The addition of dried 20% Azolla (8.14 × 10^3 kg ha^(-1)) in sand produced as much wheat biomass as the addition of the recommended NPK fertiliser (30 kg N ha^(-1)) to sand. A comparison between the topsoil and sand-grown plants showed differences in flowering time but these had no effect on the final grain and above ground biomass.
  • Full Text:
  • Date Issued: 2000

Theatre voice as metaphor : the advocacy of a praxis based on the centrality of voice to performance

  • Authors: Mills, Elizabeth
  • Date: 2000
  • Subjects: Voice , Voice culture , Acting
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2141 , http://hdl.handle.net/10962/d1002373 , Voice , Voice culture , Acting
  • Description: This study proposes a view of theatre voice as central to performance. It proposes a shift in paradigm through the foregrounding of the function of theatre voice as one of the creative strands of the theatre matrix. The function of theatre voice becomes a theatrical function. Theatre is created in the voice and, therefore, any act of theatre should include conscious questions about the meanings that are, or can be evoked through the voice in theatre. A second thrust to this study is that theatre voice practice should be included in, and theatre voice practitioners should actively engage in, broader debates about theatre. Introduction: The idea that the voice in performance is the enactment of conscious theatrical choices is set up through the notion of the theatrical use of the voice. The introduction outlines the kinds of performance contexts in which a theatrical use of the voice takes shape. This includes an assessment of the degree to which the specific South African context of the writer is useful to questions about a theatrical use of the voice. The concepts which are central to such a view of theatre voice are expanded. These are: the theatrical agency of the actor, theatre voice, the theatrical use of the voice and praxis. Selected examples from local and other productions are offered to illustrate a range of interpretive possibilities open to the voice when considered, in the first instance, as performance. Chapter one: The actor’s relationship with voice is explored through the notion of actor agency. Historically, actors were theatrically empowered by a closer involvement with playwriting, staging, apprenticeship forms of actor training and theatre management. It is argued that the emergence of the director as a new theatrical agent has diminished this actor agency. On the other hand, the introduction of a realist acting methodology has given the actor autonomy of craft, empowering the actor in unprecedented ways. The theatrical agency of actors, directors and theatre voice practitioners is explored as influencing the status and the perception of theatre voice within theatre. The proposal of the centrality of voice to performance is dependent on the agency of actors, directors and theatre voice practitioners. Chapter two: It is argued that an Aristotelian Poetics of Voice has, under the influence of realism, developed into a “Poetics of the Self”. The paradigmatic shift proposed through a view of the voice as central to theatre, is explored through a post realist, intertextuality of voice. This includes a re-consideration of the contemporary theatre voice notion of the “natural” voice. Chapter three: Cicely Berry’s work, with particular reference to The Actor and his Text (1987), is analysed in terms of realism and the theatrical use of the voice. A second focus in the analysis of Berry’s work supports the argument that voice practitioners theorise positions for theatre voice even though their texts are practical and technically orientated. Berry’s work is singled out here because the contemporary practice of the Central School tradition is the generic tradition of South African English theatre voice practice. Chapter four: Strategies and constructs are proposed in support of the centrality of voice to the theatre. Ways of realising a theatrical use of the voice are also suggested. This is based on a shift in the way in which practitioners think about theatre voice. In the first instance, it is suggested that practitioners move beyond positions of polarity and actively embrace that which is contradictory in theatre and theatre voice practice. Secondly, a traditional hermeneutic understanding of the interpretation of voice is challenged. Thirdly, the use of metaphor which is pertinent to actors, directors and voice practitioners is explored as a means to vocal action. Concrete examples of the creative use of the voice, are provided through the sonic texts of Performance Writing. By way of conclusion, some ideas are offered about the issue of empowering the actor in a theatrical use of the voice. This study is intended to contribute to a theoretical and practical debate which will promote the argument for the centrality of voice to performance.
  • Full Text:
  • Date Issued: 2000

Therapists' constructs of healthy functioning as aspirational goal in transformative psychotherapy

  • Authors: Steyn, Reinette
  • Date: 2000
  • Subjects: Psychotherapy , Mental health -- South Africa , Mental health
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:3064 , http://hdl.handle.net/10962/d1002573 , Psychotherapy , Mental health -- South Africa , Mental health
  • Description: This dissertation reviews the ways in which psychotherapists working in relatively long-term 'transformational' therapies construct the outcome goals of their interventions. It is generally accepted that a therapist's beliefs about what constitutes mental health will influence the client, and will therefore facilitate a certain outcome accordingly. A problem in a long-term, 'non-directive' therapy is that the eventual outcome is not always visible in the interim development of the client or in the business of individual sessions. Without a clearly defined 'plan' or 'goal' there is a real danger of the intervention having opposite results to what would have been desirable, or no noticeably beneficial results, both of which can be an abuse of the client's investment and trust in the process. The absence of clearly constructed goals makes it difficult to assess efficacy of a therapeutic method used to attain an improved state of mental health that will be lasting, i.e. a positive 'transformation'; it also problematises comparisons across orientations. The identification of explicit goals is of special importance in a developing 'third-world' community like South Africa, where western ('European') concepts of mental health are being offered as an alternative to so-called 'indigenous healing' and where different cultural communities may have different expectations, needs or demands of their members 'in health'. Individual-based therapeutic orientations included in the research were psychoanalysis and psychoanalytic therapies, including object-relational therapies with various emphases and self psychology, as well as transformative types of hypnosis, Gestalt therapy, client-centred therapy and transactional analysis. Twenty of the semi-structured interviews with 52 therapists working in one or more of these areas were selected for construct analysis. Through analysis of the constructs of mental health as aspirational goal that emerged in therapists' talking about their experience of the process and the consequences of therapy observed in their patients, it appeared that there are generalisable constructs across various orientations in the transformative therapies. It is hoped that these constructs may serve as a foundation for further research in the problem areas indicated, but also that therapists working in the field may use this research not only as a basis for self-evaluation, but for adding to the constructs from their own experience, to the further enrichment of the whole field of work.
  • Full Text:
  • Date Issued: 2000

Ti Gbeu

Tieou magni

Tolo

Tolon

Tonetine Bi

Topical Opinion - Organising on the mines

  • Authors: SAIRR
  • Date: 2000
  • Subjects: SAIRR
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/111247 , vital:33420
  • Description: When the National Union of Mineworkers was formed an experienced unionist said to me "organising workers in South Africa is the art of the possible". But organising workers in the mining industry is the art of the impossible. It has been the art of the impossible because it has been the art of trying to make a fundamental change in a system by using structures and instruments that were designed to perpetuate that system. It lias been the art of the impossible because it has been the art of trying to make a revolution with moderate tools tli at were invented to prevent a revolution. Because of the nature of the mining industry, which is conservative or ultraconservative by any definition, the black miner has been condemned to seek radical ends within a framework which was designed to prevent sudden and radical changes. For almost one hundred years now, black miners have not been able to change their status. The African Miners' Union in 1946 under J B Marks made an attempt but was brutally crushed by a combination of employer and government forces. It is against this background that our union has developed its organising strategies. Organising has taken place around a number of issues, some of which are safety, wages, and working- class unity.
  • Full Text:
  • Date Issued: 2000

Touba

Tougan

Tougan (Dub)

Towards an understanding of the role of commercialisation in programming at the Malawi Broadcasting Corporation from 1995 to 1998 : a case study

  • Authors: Chikunkhuzeni, Francis Chim'ndomo
  • Date: 2000
  • Subjects: Malawi Broadcasting Corporation , Broadcasting -- Malawi , Public broadcasting -- Malawi , Broadcasting policy -- Malawi , Broadcast advertising -- Malawi
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:3422 , http://hdl.handle.net/10962/d1002875 , Malawi Broadcasting Corporation , Broadcasting -- Malawi , Public broadcasting -- Malawi , Broadcasting policy -- Malawi , Broadcast advertising -- Malawi
  • Description: Competition in many market-driven media systems in advanced industrial countries can sometimes compromise traditional public service broadcast values such as programming for diversity, citizenship, minority interests and national identity. This study investigates the presence and effects of commercial-logic in a state-owned broadcaster in a developing country: the Malawi Broadcasting Corporation. Using indepth interviews and analysis of records on finance and programme schedules, the study finds overwhelming indicators of the presence of commercial logic, not driven by competition, but a commitment to provide a public service under deteriorating financial conditions. Distinguishing between the impacts of advertising and sponsorship markets on media output, the study finds contradictory effects of commercialisation. Some effects confirm some of the adverse effects of commercialisation such as heavy sponsorinfluence on programme content, self-censorship among programme producers who avoid injuring sponsors and producers paying more attention to sponsored programmes at the expense ofthe quality of some non-sponsored public service programmes. However, effects are not always contrary to public service broadcasting but may Indeed reinforce such broadcasting. Commercialisation in some instances has led to the sustenance of a range of non-sponsored public service programmes including programmes to promote culture and civic rights. In general, this study highlights the need to focus on what is realistically possible within the dynamics of the Malawi Society as a precondition for a proactive and elaborate strategy for commercialisation ofthe country's public broadcaster.
  • Full Text:
  • Date Issued: 2000

Towards reconciliation of structure with function in plasmodesmata—who is the gatekeeper?

  • Authors: Botha, Christiaan E J , Cross, Robin H M
  • Date: 2000
  • Language: English
  • Type: Article
  • Identifier: vital:6497 , http://hdl.handle.net/10962/d1004493
  • Description: Whilst the structure of higher plant plasmodesmata was first described by Robards (1963. Desmotubule—a plasmodesmatal substructure. Nature 218, 784), and despite many subsequent intensive investigations, there is still much that remains unclear relating to their ultrastructure and functioning in higher plants. We have examined chemically fixed plant material, and suggest that the conformational changes seen in plasmodesmatal substructure, particularly the deposition of electron-dense extra-plasmodesmal material, is linked to either manipulation of the hormonal balance (as in Avocado fruit), or of osmotic potential in leaf blade material. These changes result in the deposition of β 1,3-glucan (callose) at the neck region of these plasmodesmata. This electron-dense material is deposited at the neck region of plasmodesmata, and forms a collar-like structure. The formation of a collar is shown to be coupled with loss of lucence within the cytoplasmic sleeve. The formation of a collar at the plasmodesmatal orifice thus results in encapsulation and closure of the plasmodesmatal orifice. Closure of the orifice coincides with a loss of electron-lucence and a lack of resolution of the desmotubule. These ultrastructural changes are potentially significant and could contribute to, result in, or assist in the down-regulation of cell to cell trafficking via plasmodesmata.
  • Full Text:
  • Date Issued: 2000
  • Disclaimer
  • Privacy
  • Copyright
  • Contact