Using the larval parasitoid, Agathis bishopi (Nixon) (Hymenoptera: Braconidae), for early detection of false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) infested fruit
- Authors: Zimba, Kennedy Josaya
- Date: 2015
- Subjects: Cryptophlebia leucotreta , Citrus -- Diseases and pests -- South Africa , Pests -- Biological control -- South Africa , Cryptophlebia leucotreta -- Detection , Parasitoids -- Hosts , Braconidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5919 , http://hdl.handle.net/10962/d1017186
- Description: Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is one of the major citrus pests of economic importance for South Africa’s citrus industry. It is endemic to Africa, and therefore a phytosanitary pest with zero tolerance by most export markets. The cryptic nature of T. leucotreta makes visual inspection an inefficient method for detecting neonate larvae in fruit in the packhouse. Therefore, a more accurate method for sorting infested fruit at the packhouse, particularly for newly infested fruit could ensure market access. A recent study showed that fruit infested by T. leucotreta emit a chemical profile different from that of a healthy fruit. Several studies provide evidence that parasitoids locate their hosts feeding on fruit by exploiting the novel chemical profiles produced due to host herbivory. The aim of this study was to evaluate the potential of using the naturally occurring behaviour of a larval parasitoid Agathis bishopi (Nixon) (Hymenoptera: Braconidae) for detection of T. leucotreta infested fruit, by determining which compound in infested fruit is attractive to parasitoids. Ytube olfactometer and flight-tunnel bioassays with healthy and T. leucotreta infested fruit showed a significantly stronger response of A. bishopi female parasitoids to infested fruit. Among the volatile compounds associated with T. leucotreta infested fruit, D-limonene elicited the strongest attraction to A. bishopi female parasitoids. Attraction of mated A. bishopi female parasitoids to T. leucotreta infested fruit and D-limonene significantly increased after oviposition experience. Behavioural responses of A. bishopi female parasitoids that were associated with T. leucotreta infested fruit were investigated to determine which behaviours are distinct and interpretable. Probing and oviposition behaviours were the most noticeable and were only elicited on infested fruit when parasitoids contacted T. leucotreta frass, indicating that chemical compounds in frass are short-range cues used for final host location. Since production of D-limonene by fruit is elevated due to herbivory by different pests including mechanical injury on fruit, response of A. bishopi female parasitoids to compounds in frass offers a more specific and potentially useful mechanism for development of a detection system for T. leucotreta infested fruit. Chemical analysis of T. leucotreta frass and conditioning A. bishopi parasitoids to respond behaviourally to compounds in frass is proposed.
- Full Text:
- Date Issued: 2015
A customer service strategy for Ngqura Container Terminal
- Authors: Mtshiselwa, Mkhululi Terrence
- Date: 2014
- Subjects: SERVQUAL (Service quality framework) , Customer services -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/8955 , vital:26446
- Description: The container terminals play an increasingly important role in the economy of many countries. In today’s global competitive environment delivering quality service is considered as an essential strategy for success and survival. In the very competitive container terminals, service quality is important in attracting and retaining customers. The shipping companies are interested in speed and reliability from the terminals. The time a ship stays in a port must be minimised, and, therefore, the handling of containers must be executed in a fast and reliable way. The importance of customer service as a competitive strategy in container terminal has long been recognised. The growth in container volumes and higher productivity by Ngqura Container Terminal has created greater demand than before from its customers in the shipping business. The current growth in container volumes and increased customer demand has made the situation at NCT less encouraging at times, due to additional traffic of vessels awaiting to dock at the port creating congestion problems; resulting in unplanned lengthy dock occupation by vessels and the current status quo is affecting NCT strategy in terms of arrival docking and providing a quick response to customers. The Ngqura terminal is under increasing pressure from its customers and stakeholders to demonstrate that their services are customer-focused and that continuous performance improvement is being delivered. Therefore, a literature study and questionnaire survey forms the main input for this research combined with interviews with terminal managers. The purpose of this research is to examine the service quality concepts and offer an operational approach for the measurement of the quality of Ngqura Container Terminal services. The main research problem in this study was to identify customer service strategies that could be applied by Ngqura Container Terminal in order to maintain and exceed its business growth as well as customer expectations? The study employed the SERVQUAL model as a measuring tool in establishing the customers’ general expectations of a service and their perceptions of the service received at Ngqura Container Terminal. The five elements of SERVQUAL, which are tangibles, reliability, responsiveness, assurance, and empathy, were used to deal with and solve the main problem. Below are the sub-problems that have been identified in order to investigate and develop a research strategy: What is the customer’s perception of service quality at NCT?; What are the specific customer service requirements of NCT’s customers?; Does NCT’s service operations performance enable it to fulfill its customer service requirements?; How can the performance gap between customer service requirements and service operations performance be bridged?; Which service quality elements are important to customers for container terminals? This study wants to concentrate on the customers’ perception and evaluation toward service performance in Ngqura Container Terminal.
- Full Text:
- Date Issued: 2014
The impact of a budget deficit on transport infrastructure investment in South Africa
- Authors: Nanto, Aphiwe
- Date: 2013
- Subjects: Budget deficits -- South Africa , Infrastructure (Economics) -- South Africa , Transportation -- South Africa , Debts, Public -- South Africa
- Language: English
- Type: Thesis , Masters , M Com
- Identifier: vital:11478 , http://hdl.handle.net/10353/d1015245 , Budget deficits -- South Africa , Infrastructure (Economics) -- South Africa , Transportation -- South Africa , Debts, Public -- South Africa
- Description: Persistent government budget deficits and government debt have become major concerns in both developed and developing countries. This study investigates the impact of a budget deficit on transport infrastructure investment in South Africa. Quarterly time series data, covering the period 1990q1- 2009q4, was used in this project. The study tests for stationarity using the Augmented Dickey- Fuller and Phillips Perron; it tests for cointegration using the Johansen (1991, 1995) methodology. A vector error correction model is used as an estimation technique. The results of this study show that a budget deficit has a negative impact on transport infrastructure investment in South Africa.
- Full Text:
- Date Issued: 2013
The influence of individual employee performance metrics on a sub-culture in a professional services firm in Durban, South Africa
- Authors: Zvarevashe, Marshall
- Date: 2013
- Subjects: Performance -- Evaluation Corporate culture -- South Africa Organizational effectiveness Leadership Management -- South Africa Organizational behavior -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:714 , http://hdl.handle.net/10962/d1001868
- Description: In today’s fast paced and global economy, competitive advantage is increasingly focused more on organisational behaviours rather than on the traditional tenets of land, labour and capital. Going beyond the traditional, organisations that are best able to get the most and the best out of their people are the ones most likely to perform better. This study aims to build an understanding of how culture is influenced by individual employee performance metrics that are used in an organisation. Previous research has been done in the broad fields of organisational culture and employee performance metrics separately, but no studies were identified in literature that focused on the interaction of the two concepts specifically. Therefore, this study seeks to answer the following research question: How do individual employee performance metrics influence sub-culture in the context of a professional services firm in Durban? This study predominantly focused not on performance at the organisational level, but rather the more granular level of individual employee performance metrics and sub-culture in one of the divisions of a professional services firm. This qualitative study explores the multiple perspectives of reality of ten of the 32 managers in the Advisory division of a professional services organisation, regarding how individual employee performance metrics influence their world view of work, or the way they perceive, think, feel and interact in the world of work. The focus of the study was limited to one department, in one branch of a multinational organisation and focused only on the horizontal layer of the “manager group” within the staff levels. Semi-structured, in-depth and face-to-face interviews were conducted with these managers as a means of gathering and saturating data. Interviewees were identified using a stratified sampling from the group of managers in the Advisory division. Open coding and constant comparison was used to analyse data. Page ii of viii The results of the study show that managers had very varied and complex perceptions of how the individual performance metrics used to assess their performance influence the sub-culture of their world of work. The key findings manifested that misuse and abuse of performance metrics by leaders, leadership bias in respect to recognition, reward and remunerations, the predominant focus of the division on the bottom line and emphasis on success at all cost, and low employee morale were all aspects of performance that impacted on how employees behaved in the division. The effect of these factors on the managers operating in this division was that there were low levels of employee commitment which were experienced through low morale and reduced productivity; managers felt that there was a restriction in the development of their careers, all of which resulted in a disregard to values of the organisation. This study reflects how the reward and recognition system using the balanced scorecard has shifted the focus of the department away from the organisation’s espoused values. This has resulted in various leadership and management questions for the leadership of the division in this study. This research also adds to existing literature that links performance and culture within the organisational context that it goes beyond the prevalent themes in literature which focus on performance at the organisation level. This study focuses on performance at the employee level and in particular in a professional services firm in South Africa. The study has three interrelated sections which are however considered as standalone. The first section is an evaluation report based on the Advisory division of a professional services firm in Durban, South Africa, and consists of a literature review, the methodology followed in conducting the study, results and the discussion thereof. The report also highlights limitations of the study, recommendations and the perceived value of the study. The report ends with a summary in the form of a conclusion. Section 2 comprises a more comprehensive literature review while Section 3 documents the research methodology followed in the study.
- Full Text:
- Date Issued: 2013
Evaluation of antidiarrhoeal and toxicological properties of Hermannia Incana cav.: a South African medicinal plant
- Authors: Appidi, Jaipal Reddy
- Date: 2010
- Subjects: Sterculiaceae , Medicinal plants -- South Africa -- Eastern Cape , Diarrhea , Botany, Medical
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11304 , http://hdl.handle.net/10353/259 , Sterculiaceae , Medicinal plants -- South Africa -- Eastern Cape , Diarrhea , Botany, Medical
- Description: Hermannia incana Cav. (Sterculiaceae), known as sweet yellow bells, is a medicinal plant used by the people of the Eastern Cape for the treatment of stomach-ache and diarrhoea. It has purgative and diaphoretic effects. It is a prostrate herb with yellow flowers and sparsely hairy and slightly glandular leaves, occurring in grassland and marshes in the Eastern Cape Province of South Africa. Based on the ethnomedical uses of this plant, the research project was designed to evaluate its antidiarrhoeal and toxicological properties. An ethnobotanical study of plants used for the treatment of diarrhoea in the Eastern Cape Province was carried out, using a questionnaire which was administered to herbalists, traditional healers and rural dwellers. This survey indicated a total of 17 plant species from 14 families. Elephantorrhiza elephantine (Burch.) Skeels, Hermannia incana Cav., Pelargonium reniforme Curt., Alepidea amatymbica Eckl. & Zeyh. and Bulbine latifolia (L.f.) Roem. et Schult. were the most frequently mentioned and highly recommended plants for the treatment of diarrhoea by both the traditional healers and rural dwellers. The root, bark and leaves are the common parts of plants used, while decoctions and infusions are the main methods of preparation. The agar dilution method was used to study the antimicrobial activity. The methanol extracts of the plant showed appreciable activity against Gram-positive and Gram-negative bacteria at concentrations ranging from 0.5 to 7.0 mg/ml. The acetone and water extracts of both the leaves and the roots showed moderate activity against Gram positive bacteria and less activity against Gram negative bacteria. All the extracts inhibited the growth of the fungi Aspergillus flavus, Aspergillus niger, and Mucor hiemalis with growth inhibition ranging from 54.31 percent to 96.67 percent at 0.1-10 mg/ml. None of the extracts suppressed the growth of Candida albicans at the maximum concentration (10 mg/ml) tested. iii In the in vivo antidiarrhoeal evaluation using Wistar rats, the aqueous extract at all the doses tested, significantly prolonged the time of induction of diarrhoea and also reduced the frequency of diarrhoeal episodes and fecal parameters (total number, number of wet, fresh and dry weight and water content of the faeces). The percentage inhibition of defecation and intestinal content (enteropooling) were increased in dose dependent manner. The doses also reduced the intestinal transit time of charcoal, masses and volumes of intestinal fluid (gastrointestinal motility). These results are indications of antidiarrhoeal property of H. incana leaf extract with the 600 mg/kg body weight of the extract being the most effective. In the toxicological evaluation using Wistar rats, the oral administration of the extract did not produce any significant effect on the liver and kidney body weight ratios, RBC, HB, PCV, MCV MCH, MCHC, RCDW, WBC, neutrophils, monocytes and basophils cholesterol, triacylglycerol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and atherogenic index. The extract also did not affect the levels of sodium, potassium, chloride, inorganic phosphorus, urea, creatinine, total protein, globulin, albumin, total and conjugated bilirubin. The activities of alkaline phosphatase, gamma glutamyl transferase and alanine aminotransaminase in the serum were increased by the extract whereas aspartate aminotransaminase was decreased. The levels of LUC, platelets, lymphocytes and eosinophils were significantly affected at 600 mg/kg body weight. The available evidence in this study suggests that the extract of H. incana leaf is mild, parameter and dose specific. The structure and distribution of foliar appendages on the leaves of this plant were investigated with the JEOL (JSM-6390LV) scanning electron microscope (SEM). Both glandular and non-glandular trichomes were observed. Long stalked glandular trichomes were present on both the abaxial and adaxial surfaces while short stalked glandular trichomes were present only on the adaxial surface. Glandular trichomes were capitate while nonglandular trichomes were stellate with many arms. Energy dispersive X-ray spectroscopyiv SEM showed that Al, Ca, K, Na, Ti and Si were the major constituents of the crystals analyzed from the leaf surfaces. The phytochemical screening of H. incana revealed the presence of bioactive antidiarrhoeal agents such as alkaloids, tannins, saponins, phenolics, triterpenes, cardiac glycosides, flavonoids, cardenolides and dienolides. Two flavonoids, epicatechin and 3, 5, 7, 2’ tetra-hydroxy flavone-3- O--D-glucopyranoside were isolated from the leaves of the plant through bio-active guided fractionation. Both these compounds were screened against diarrhoea causative organisms (Echerichia coli, Shigella flexneri, Bacillus cereus and Staphylococcus aureus) and exhibiting minimum inhibitory concentrations ranging from 12.5 to 100 μg/ml. The findings from this research have generally justified the traditional use of this plant for the treatment of diarrhoea in this province.
- Full Text:
- Date Issued: 2010
Volatility and the risk return relationship on the South African equity market
- Authors: Mandimika, Neville
- Date: 2010
- Subjects: Stock exchanges , Financial risk -- South Africa , Saving and investment -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1009 , http://hdl.handle.net/10962/d1002744 , Stock exchanges , Financial risk -- South Africa , Saving and investment -- South Africa
- Description: The volatility of stock markets has important implications for investment decision making, financial stability and overall macroeconomic stability. This study examines the risk-return relationship as well as the behaviour of volatility of the South African equity markets using both aggregate, industrial level and sector level data. The study is divided into three parts. The first part investigates the behaviour of volatility in each of the industries, sectors and the benchmark series focussing on whether volatility is symmetric or asymmetric. Subsequently we investigate which, among the GARCH family of models appropriately captured the riskreturn relationship under which distributional assumption. The second part examines the riskreturn relationship on the SA stock market. The third part examines the long term trend of volatility and whether volatility significantly increases during financial crises and during major global shocks. The GARCH-M, EGARCH-M and TARCH-M models under the Gaussian, Student –t and the GED are used. The findings this study makes are as follows: firstly, there is no clear relationship between risk and return. Secondly, volatility is asymmetrical, implying that bad news has a greater effect on volatility than good news in the South African equity market. Thirdly, the TARCH-M model under the GED was found to be the most appropriate model. Fourthly, volatility increases during financial crises and major global shocks. Overall, volatility is generally not priced on the South African equity markets. Thus, both local and international investors need to consider other factors that influence returns such as skewness. The general increase in volatility during financial crises and major global shocks poses a major concern for policy makers as this may cause financial instability. Thus policy makers need to be mindful of the behaviour of volatility in the South African equity market in response to external shocks.
- Full Text:
- Date Issued: 2010
An investigation of newsroom convergence at the MoAfrika media company in Lesotho and its implications for gatekeeping: a qualitative case study
- Authors: Senthebane, Teboho
- Date: 2009
- Subjects: MoAfrika Convergence (Telecommunication) Mass media -- Management -- Lesotho Journalism -- Management -- Lesotho Journalism -- Technological innovations -- Lesotho
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3501 , http://hdl.handle.net/10962/d1006112
- Description: This research is based on a case study of MoAfrika, a news organisation that has embraced digitisation to produce and distribute content across three platforms. It draws upon observation and in-depth interviews to show how MoAfrika's embrace of a degree of convergence has led to a fragmentation for journalists whose daily work now include additional responsibilities and pressures of time. While there is an increase in the quantity of news disseminated via radio, newspaper and online, questions arise about the quality of such news produced in a multi-skilled, multiple media news production environment. The result is repurposed stories with little original content and augmented employee workloads without training and compensation. The study examines these issues drawing on theories of gatekeeping and convergence. The decision to include a news story at MoAfrika depends partly on which medium it fits into most easily. News values, deadlines, organisational norms and national trends are some of the considerations which factored into gatekeepers' decisions. Primary decision-making was made within a group which also considered expense and expertise, and where the Managing Editor made the final call and set the frameworks for how content played across the enterprise's three platforms.
- Full Text:
- Date Issued: 2009
An investigation into the popularity of the Zimbabwean tabloid newspaper, uMthunywa: a reception study of Bulawayo readers
- Authors: Mabweazara, Hayes Mawindi
- Date: 2007
- Subjects: uMthunywa (Zimbabwe) Tabloid newspapers -- Zimbabwe Journalism -- Zimbabwe Newspapers -- Marketing -- Zimbabwe Mass media -- Social aspects -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3454 , http://hdl.handle.net/10962/d1002908
- Description: The development of the tabloid press has stirred heated debate among media scholars. Critics have argued against the relevance of tabloids in society, often framing them as the ‘journalistic other’ deserving no place in ‘serious’ journalism. Much of this criticism, however, has not been based on a close interrogation of the phenomenon, or an examination of the reasons for their popularity amongst readers. It is against this background that this study investigates the reasons behind the popularity of the Zimbabwean state-controlled tabloid newspaper uMthunywa, among its Bulawayo readers. In particular, it explores the meanings obtained from the content of the paper and the relevance of this content to the readers’ everyday lives. In undertaking this investigation, the study draws primarily on qualitative research methods, particularly qualitative content analysis and in-depth interviews (both group and individual). As the study demonstrates, these methods uncover the complex manner in which Bulawayo readers are attracted to uMthunywa and how they appropriate its textual meanings to their lived realities. The study establishes that despite uMthunywa being state-controlled, it offers space through which the conventional ways of presenting reality are challenged, and the importance of the newspaper being written in isiNdebele. As the study indicates, the popularity of the newspaper is largely dependent on its excessive formulaic and sensational stories, which cover issues experienced by its readers in their lived circumstances. The study thus argues that the newspaper constitutes an alternative mediated public sphere that finds space in the deeper social conditions that have alienated the people of Bulawayo from the macropolitical life of the nation and the ‘power bloc’.
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- Date Issued: 2007
An investigation of the management and leadership experiences of female school principals in the Ondangwa education regions
- Authors: Udjombala, Maria
- Date: 2002
- Subjects: Women school principals -- Namibia -- Ondangwa Educational leadership -- Namibia -- Ondangwa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1653 , http://hdl.handle.net/10962/d1003536
- Description: This study explores practical school leadership and management, as enacted by women. The study, conducted in an interpretive paradigm, attempts to gain an understanding of women’s subjective experiences of school leadership and management. Two women principals from Ondangwa West Educational Region were interviewed. The two were selected through consultations with one of the senior inspectors in the region. Both had been principals for more than ten years and were seen by those who are concerned with their school to be successful. The study found that these women prefer a participative style of leadership and management, characterised by consultations with others, teamwork, collaborative decision-making and the use of power to empower others. They also strive for good human relationships because they believe that it fosters mutual respect, trust, openness and a good working atmosphere. All these human centred approaches are directed towards creating a school atmosphere that is conducive to teaching and learning and therefore result in effective schooling and quality educational outcomes. They do not experience gender discrimination in their work places. They have the full support of their supervisors. Though both are married with children, these dual roles do not prevent them from being successful in their professional work. In fact they have reached a stage where they feel confident as leaders and feel that they are acting as role models for fellow women principals and those aspiring to this position. The study concludes that the styles of leadership and management displayed by women are similar to those that are universally accepted as characteristics needed for effective school management and leadership. Though these leadership styles are traditionally associated with women, these characteristics are not gender specific. Therefore it will be in the best interest of schools, if school principals, both men and women, could borrow from these qualities in order to change schools from authoritarian to more democratic institutions.
- Full Text:
- Date Issued: 2002
A critical investigation of conflict management : a case study of a Namibian institution
- Authors: Uiras, Hilja
- Date: 1999
- Subjects: Conflict management -- Namibia Conflict management -- Study and teaching Culture conflict Social conflict Conflict management -- Namibia -- Case studies Conflict management -- Study and teaching -- Case studies Culture conflict -- Namibia -- Case studies Social conflict -- Namibia -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1480 , http://hdl.handle.net/10962/d1003361
- Description: This study is a qualitative interpretative study of conflict management in a multicultural Namibian institution. The focus of the study is to understand how individual people in a particular organization perceive conflict, the possible sources of conflict as well as to explore the possible strategies of managing conflict. This is followed by an analysis of the general educational cultural and social characteristics of Namibia, which relate to the sources of conflict. I also make an attempt to have a deeper understanding of people from different cultural and educational backgrounds in viewing conflict and how these differences might be seen as major sources of conflict and how they deal with it - by using a case study approach. I interviewed 5 participants from different cultural backgrounds. The major research methodology I used in this study is in-depth interviews that allowed me to explore people's understanding of, attitudes to and views on conflict. I supplemented the interviews with participant observation, which allowed me to get first-hand information on how people interact socially and in meetings in order to explore possible sources and existence of conflict in meetings and how the staff dealt with it. Furthermore, I tried as much as possible to observe daily activities as an observer. People interviewed have different perceptions about conflict. Some use conflict to their advantage to arouse discussion and stimulate creative thinking. Some people find conflict to be a burden, something to be minimized. This avoidance leads to poor decisions and poor use of teams as a way to improve both decision making and acceptance of the decisions that are made. Cultural differences among staff and the process of reform emerge as the major sources of conflict. Whether a conflict will result in negative or positive consequences, or both, will depend to a large part on the strategy taken to resolve the conflict.
- Full Text:
- Date Issued: 1999
Preliminary investigation of the molecular pathogenicity determinants of Xanthomonas campestris pv. zeae
- Authors: Downing, T G
- Date: 1998
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4066 , http://hdl.handle.net/10962/d1004922
- Description: Xanthomonas campestris pv. zeae was shown to posses a vast range of potential plant cell wall degrading enzymes including at least one protease, a carboxymethylcellulase, pectin lyase, polygalacturonase and a B-endoglucanase. Replicon stability and transfer system efficiencies were determined for a range of oriC, and oriT -tra combinations, and suitable vectors were constructed and identified for insertional inactivation by homologous recombination. Ideal suicide replicons were found to be pACYC184 and p15A, while P, Wand Q group replicons were supported by X campestris pv. zeae. Group P and group N transfer systems were shown to be highly efficient in intra-genus matings between Escherichia coli and X campestris pv. zeae, with the exception of P-tra systems in trans for the delivery of Tn5. Various cloning vectors were tested for stability and mobility. Tn5 was shown to transpose at high frequencies into the genome of the bacterial plant pathogen, and insertion was relatively random. Suitable screening assays were established to allow rapid isolation of mutants with potential virulence or pathogenic deviations, after mutagenesis. Two non-pathogenic mutants were identified, one of which was a putative hrp·, while the other was a leaky virulence. A single mutant showing 40% reduced protease activity was also shown to exhibit reduced virulence indicating a minor role for the protease in pathogenicity. The majority of virulence mutants showed altered growth in different levels of nutritional availability and complexity. Nutritional viability (the ability to acquire and use nutrients at a sufficient rate to grow fast enough to overcome host defences) was shown to be essential for virulence and possibly pathogenicity. Wild-type in-planta behaviour was analysed and growth and spread patterns typical for pathogenic response identified. Chief amongst these was the requirement for a threshold level of cells per leaf area or length, before symptoms could develop. Occlusion of vascular bundles was shown not to be the primary factor in the pathogenicity of X campestris pv. zeae. Threshold levels for lesion development indicate the absence of a diffusable lesion forming element, and possibly the requirement of cell density for induction of certain functions. , KMBT_363
- Full Text:
- Date Issued: 1998
The pre-service preparation of secondary school mathematics teachers: a case study of curriculum effectiveness
- Authors: Msomi, Dumile Dennis
- Date: 1995
- Subjects: Mathematics -- Study and teaching (Secondary) -- South Africa -- Curricula Mathematics teachers -- Training of -- South Africa -- KwaZulu-Natal -- Esikhawini College of Education
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1711 , http://hdl.handle.net/10962/d1003594
- Description: The quality of education in most historically black schools is a source of concern for many people. The high failure rate in mathematics in particular, is believed to result in part, from the inadequacy of the teacher preparation programs at many of the colleges of education in the country. Esikhawini College of Education in KwaZulu-Natal is one of the colleges which is involved in the preparation of secondary school mathematics teachers. The appropriateness of the mathematics curriculum of this College was the subject of the study. In particular, the study aimed at the following: (i) To analyse aims and philosophies underlying the prescribed mathematics curriculum of the College. (ii) To establish the teacher educators' and student teachers' perceptions of the appropriateness of the curriculum in general. (iii) To establish the teacher educators' and student teachers' perceptions of the mathematics curriculum content and processes. (iv) To establish the quality of available materials used at the College for realisation of the curriculum goals. (v) To offer proposals and recommendations for the improvement of the education of prospective secondary mathematics teachers. Data about the perceptions of the appropriateness of the mathematics curriculum was gathered through a questionnaire which was administered to one hundred and one student teachers. The issues that arose from the questionnaire study were followed up by an interview study. The interview schedule was administered to a sample of fourteen student teachers and all six mathematics teacher educators in the College. In addition, a survey of mathematics materials available at the College library and in the mathematics department was carried out to collect further data. Some of the significant findings of the, study were : • Limitations in the College mathematics curriculum in as far as the curriculum content and processes were concerned. • Inadequacy of mathematics curriculum materials that were available and used at the College. • Low attainment in mathematics at matriculation level of most of the student teachers. • Widespread dissatisfaction with the curriculum, especially that of Mathematics Didactics. The implications of the findings for the College were considered. Amongst other suggestions is the suggestion that the College introduces a preliminary STD course in which prospective student teachers' mathematics background is enriched to enable them to cope with the demands of the College curriculum.
- Full Text:
- Date Issued: 1995
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.
- Full Text:
- Date Issued: 1992
A contribution to the oceanology of the Prince Edward Islands
- Authors: Parker, Llewellyn Derek
- Date: 1985
- Subjects: Oceanography -- Prince Edward Islands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5605 , http://hdl.handle.net/10962/d1002055
- Description: While the terrestrial ecosystem of the Prince Edward Island Group has been subject to intensive research, the marine ecosystem has to a large extent been neglected. This together with the possible existence of an "island effect" at these islands, as was first proposed after the visit to these islands of the French vessel Marion Dufresne, led to the initiation of a programme to determine the distribution of standing stocks and the productivity of phytoplankton and zooplankton in the neritic seas of these islands. To do this and before a detailed biological survey could be attempted, it was first necessary to define the physical and chemical properties of the circuminsular waters. This dissertation discusses the results of several surveys to these islands in the light of a possible "island effect" and comments upon processes likely to influence such an effect
- Full Text:
- Date Issued: 1985
A polarographic study : the estimation of sodium and potassium in the presence of each other
- Authors: Carter, Austin John
- Date: 1938
- Subjects: Polarographs , Polarography , Potassium , Sodium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4455 , http://hdl.handle.net/10962/d1010434
- Description: The polarographic method has been described, and an attempt made to describe the difficulty of the simultaneous deposition of sodium and potassium. Various methods have been examined, of which precipitation of potassium with magnesium dipicrylaminate seems the most promising. The quantitative results were unsatisfactory, and possible sources of error are discussed. The method, while very convenient, rapid and labour-saving, is not sufficiently standardised to be trustworthy.
- Full Text:
- Date Issued: 1938