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Seed bank dynamics of selected vegetation types in Maputaland, South AfricaKellerman, Millicent Johanna Susanna 01 February 2005 (has links)
The seed bank dynamics of five selected vegetation types within the Tembe Elephant Park, Maputaland, northern KwaZulu-Natal, South Africa, were investigated. The different vegetation types from which soil samples were randomly collected during the entire year of 2001 are (a) the very rare and unique Licuati forest and (b) Licuati thicket vegetation, (c) a bare or sparsely vegetated zone surrounding the forest edges, the forest/grassland ecotone, dominated by cat’s tail grass (Perotis patens), (d) grassland and (e) woodland (dense savanna). The main idea of this study was to gain a better understanding of the dynamics of some of Maputaland’s most interesting and unique vegetation types. The aims were to obtain an estimate of the seed bank size, determine the species composition of the soil seed bank flora and compare the species composition with the aboveground vegetation, as well as to compare species richness between the seed bank and the standing vegetation in these selected vegetation types. Seed bank size and species composition was determined mainly by using the seedling emergence method. Soil samples were collected at three-month intervals to obtain a measure of the temporal variation in size and composition. The comparison between the seed bank flora and standing vegetation was done by means of a transect method. The depth distribution of seeds in the soil profile was investigated by collecting soil samples at six different soil depths. Soil seed densities obtained by the seedling emergence and flotation methods were also compared. Results showed that the forest/grassland ecotone and grassland vegetation types produced the largest soil seed bank in terms of seed densities and the Licuati forest and thicket vegetation the smallest, in fact the latter had almost no persistent seed bank. Within each vegetation type the seed bank size showed clear seasonal variation. Seed distribution was concentrated in the upper soil layers. The flotation and physical separation method produced much larger seed numbers than the seedling emergence method. Generally, there is no or very little correspondence between the number of species recorded in the seed bank and that of the standing vegetation. It was found that the seed bank of the different vegetation types, if present, was a fairly poor predictor of the species composition of the existing vegetation, especially in terms of woody species. / Dissertation (MSc (Botany))--University of Pretoria, 2006. / Plant Science / unrestricted
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Identification of molecular markers in wheat and maize using AFLP technologyVan Niekerk, Izak Schalk Petrus 01 February 2005 (has links)
The optimisation and implementation of a molecular fingerprinting system and its ultimate use in marker assisted selection of identified maize and wheat genotypes for the CSIR are described in this dissertation. The Amplified Fragment Length Polymorphism (AFLP) method was optimised for the maize trait gamete sterility, and for the wheat traits eye spot resistance and cytoplasmic male fertility. Maize and wheat DNA were extracted from selected genotypes employing standardized protocols. A commercial AFLP kit was used to obtain suitable fingerprint fragments for analysis. As this kit was not designed for very large genomes, conditions for the large wheat genome required optimisation. AFLP fingerprints generated from the different genotypes of maize and wheat were evaluated for potentially trait linked markers. Polymorphic fragments were identified by their presence in genotypes containing the trait of interest, and their absence from fingerprints of genotypes that did not contain the trait of interest. These amplification products were identified and selected as possible markers. These potential markers were converted to Sequence Characterised Amplified Regions (SCARs) by cloning the selected amplification products to T-tailed pSK vector, and subsequent sequencing of the fragment. Primers were designed to recognise these amplification regions in the tested genotypes. Primers were optimally designed to include or exclude the restriction sites of the enzymes at each end of the amplified fragments and annealing temperatures normalised for each of the primer sets. The primers were validated by amplification of the tested genotypes with the primer sets at specific reaction and temperature cycling conditions. For maize, two primer sets were identified that could be developed to identify gamete sterility genotypes. In the case of wheat, one primer set for each of the traits spot resistance and cytoplasmic male fertility was identified for their potential use as markers. / Dissertation (MSc (Genetics))--University of Pretoria, 2006. / Genetics / unrestricted
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Modulation of oxidative stress parameters in healthy volunteers by strenuous exerciseDe Haaij, Yolanda 31 July 2007 (has links)
Antioxidant additives to foods and beverages are important marketing tools. However, little evidence exists on the bio-availability of such antioxidants. Strenuous exercise is expected to induce reversible oxidative stress in healthy volunteers. This is expected to lead to a decrease in antioxidant levels and an increase in lipid peroxidation levels and the Oxidative Stress Ratio. By measuring the ability of an ingested antioxidant to decrease the exercise-induced oxidative stress, information of its bio-availability can be obtained. Therefore an exercise protocol able to consistently induce oxidative stress can be a valuable tool in antioxidant efficacy and bio-availability studies. For this dissertation three different exercise studies, the First, Second and Third Exercise Study were undertaken to investigate the effect of strenuous exercise on plasma and salivary oxidative stress parameters in healthy volunteers. The DPPH Assay was employed as a measure for total antioxidants in plasma and saliva and the TBARS Assay was used as a measure of plasma lipid peroxidation. The Oxidative Stress Ratio, a combined value for the DPPH and TBARS markers was calculated from these values. Some sports physiology parameters were also measured. The possible use of two markers of protein carbonylation as an indication of oxidative stress following exercise was also investigated. They were a spectrophotometric assay, the DNPH Assay and a Western blot method, the Oxyblot™ method. Not one of the three exercise studies succeeded in modulating the oxidative stress parameters in the expected direction to a statistically significant level. Possible improvements for future studies are discussed and include the prescreening of volunteers to exclude exercise tolerant volunteers. / Dissertation (MSc (Biochemistry))--University of Pretoria, 2007. / Biochemistry / MSc / unrestricted
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Effect of TDS content of water on the selenium status and certain growth parameters of mutton sheepHolele, Kabelo Kgomotsego Odirile 31 July 2007 (has links)
Selenium (Se) is an essential mineral in the animal body for effective metabolism and health reasons. It can also have toxic effects if ingested in amounts exceeding the body’s metabolic requirements for extended periods (Underwood and Suttle, 1999). Its processes are not fully understood due to its intricate metabolism and its variable responses in the presence of other heavy metals (Rosenfeld, and Beath, 1964; Diplock, 1970: and Georgievskii, et al., 1982). Arthur and Beckett (1989) and Echevarria, et al. (1986) noticed that both the deficiency and toxicity of Se affects a wide range of enzymes and metabolic processes. It may thus affect many pathways due to the changes in hormonal concentrations. Se has been observed in the groundwater of livestock across different regions of South Africa at concentrations exceeding the recommended guideline ranges (Casey and Meyer, 2001: Casey et al., 1998; Department of Water Affairs and Forestry, 1996). The respective water was classified as potentially hazardous in some instances and unacceptable in others. It may help cause several health and reproduction problems in livestock and wildlife (Elsenbroek et al., 2003). The marginal difference between adequacy and toxicity of Se in the animal body led to investigations into the effect of the total dissolved solids (TDS) content of the water on the selenium status and its effect on production parameters of mutton sheep over a ten-week period. The guideline limit for Se in drinking water is 0,05 mg / L (DWAF, 1996) with a target water quality range of 0,02mg / L (WRC, 2004). Se was supplemented at 0,7 mg / L during the trial and TDS was given at 3000 mg / L. Animals not receiving Se were less productive than those that received Se. Those that received both Se and TDS grew as well as those supplemented only with Se, but were more efficient. They seemed to accumulate less Se in the blood. Their excretory mechanisms and the functioning of their homeostatic controls against both Se deficiency, at first, and at a later stage against chronic selenosis, were more suitable. Further research exposing the animals for a longer time period and in an extensive production system would assist in quantifying these results. / Dissertation (MInst.Agrar (Animal Production))--University of Pretoria, 2007. / Animal and Wildlife Sciences / MInst.Agrar / unrestricted
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A study of the preparedness for a changing employment environmentLabuschagne, Johannes Christiaan 02 August 2004 (has links)
The world has, according to Toffler (1984), passed through three 'waves' of socio-economic development. These waves of development were brought about by changes in the technology related to economic activity. These technological developments also changed the social complexion of society. The first wave of change, was from a hunter-gatherer society to an agricultural society, while the second was from an agricultural to an industrialised society. The third wave of change is the focus of this study, which deals with the transformation from an industrial society to the so-called 'third wave' or information age and society. This transformation was brought about mainly by two factors, although there were many other influences that contributed to the change. The first factor was the technological development of electronic information and communication technologies that enabled the other influences to have such a telling effect on society. The second factor was the globalisation of the world economy, which occurred as a result of rapid technological developments, but also as a result of political changes such as the so called fall of the iron curtain after the dismantlement of the Soviet republics and subsequent economic freedom in the former Soviet Union. The Chinese economy followed the trend towards liberalisation and a more capitalistic orientation, signaled by events such as the return of Hong Kong to China from its British colonial occupancy. Globalisation and the development of information technologies has had far reaching consequences on the world economy and society and resulted in the formation of a 'new wave' economy where companies are becoming specialised, concentrating only on core business, to enable optimum penetration of the market in a specific area. As a result of specialisation, companies are contracting out non-core functions to independent contractors and as such, employing less permanent employees. Companies can thus employ specialists in non-core functions at competitive prices. This lead to the phenomena of 'job shift' from permanent employment to contract and temporary employment. Large segments of the world population are resisting globalisation and job shift, because of the subsequent losses in permanent employment and increased unemployment. Social protection for contract and temporary employees are not adequate compared to the protection for permanent employees. South Africa as a developing country, is not well positioned to absorb the effects of job shift. The standard of education in the country is low and a large portion of the population is engaged in elementary occupations. People engaged in certain technology companies such as Information Technology, are more suited to job shift compared to labour intensive companies such as the South African mining and construction industry. A survey was done to establish the preparedness of Middle Managers in a hard rock mining company and specifically whether there is a significant difference between the preparedness of employees engaged in mining related, finance, human resources, and engineering related occupations. Results indicated that all respondents were aware of the phenomenon of job shift and it was understood that the trend would increase. No significant difference was found between the preparedness of the various occupational categories. It was anticipated that employees engaged in the core business of the Company, namely mining, would chose to remain in permanent employment in the mining industry, but it was found that more than 50% of all respondents proposed to apply for another permanent position in the hard rock mining industry should their jobs became redundant. More than 70% proposed to remain in the same industry. This indicated that respondents were not prepared for job shift. Although the phenomenon of job shift was known to and understood by respondents, it was perceived not to be a real threat or opportunity. In order to have a workforce more prepared to job shift, the researcher proposes that companies need to familiarise their employees with the skills and attributes of an entrepreneur. This will benefit the Company in moving towards a 'third wave' organisation and will also lessen the negative effects of future job losses. / Dissertation (MCom (Labour Relations Management))--University of Pretoria, 2005. / Human Resource Management / unrestricted
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Die geldigheid van die OPQ vir die voorspelling van werksukses (Afrikaans)Muller, Roald 02 August 2004 (has links)
The study was undertaken at a financial institute at which a personality test questionnaire serves as the predictor. The personality questionnaire serves as a selection instrument for new appointed branch managers. The criteria are a performance appraisal rating in terms of how he performs in his job. The selection of employees is a difficult and subjective process. It is, however, of utmost importance for the organisation and the employee that the selection procedure must be effective and scientifically sufficient. It was not clear whether test results could be used to predict work success. Viewed in this context the objective of this study is to determine predictive validity of the OPQ (Occupational Personality Questionnaire) for job success in a financial institution. The literature study was conducted in accordance with guidelines established by Herold (1972:11-15) with emphasis on selection, the criteria for job success and the concept of validation. The theory regarding psychological testing was researched and the rational behind existence and applicability of the predictor was researched. The study was conducted with regard to 94 test cases in four regions, Gauteng North, Gauteng East, Gauteng West and Gauteng South. The statistical processing was performed by means of the SSPS computer software programme. The population and descriptive statistics were researched. It is evident from the results of this study that the OPQ questionnaire is not valid for the use of predicting work success. It is however recommended that the study must be tested on a more normal divided target group. Furthermore it is recommended that the performance measurement process must be revisited. / Dissertation (MCom (Human Resources Management))--University of Pretoria, 2005. / Human Resource Management / unrestricted
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The implementation of career management practices in the South African Public ServiceHartzenberg, Johannes Stephanus 02 August 2004 (has links)
In the past human resource management practices in the South African Public Service did not place any emphasis on the development and implementation of career management programmes or practices. The career paths of employees were largely dictated by the prescripts and measure applicable to the various occupational classes in the Public Service. Consequently the career development of public servants, especially lower level workers such as cleaners and labourers, was neglected. However, following the dawn of the democratic order in 1994, a massive process unfolded to rationalize and restructure the Public Service. With the advent of this new political dispensation for South Africa, the transformation of the human resource management practices of the Public Service received priority attention. In spite of the prominence given to career management in the South African Public Service by various government policies and white papers, it was suspected that career management, as a human resource management practice, is not receiving the necessary attention that it deserves. This study was therefore undertaken in order to determine the extent of implementation of career management programmes in the South African Public Service. Not only was the population group of the study made up of all government departments, a sample of four statutory organizations were also approached to participate in the study. The study was executed with the following objectives in mind: 1. To determine the state of affairs as far as the implementation of career management programmes in government departments are concerned. 2. To determine the reasons why government departments have not implemented and activated career management practices (if applicable). 3. To determine the nature of the practices that have already been put in place by departments. As a first phase to the study, a literature review was undertaken. During this review numerous articles and books written by reputable persons in the field of human resources management were studied. The literature research mainly focused on the purpose of career management, the role players responsible for it and the elements thereof. Emanating from the literature study, the research design and strategy were decided upon. A population group was identified and data was obtained from respondents by means of a questionnaire especially developed for this purpose. The data was statistically processed after which conclusions and recommendations were made. Recommendations made focused on the creating of an awareness of career management as well as practices that support it. These practices include career planning and pathing, performance management, co-ordinated departmental career development programmes, organisational needs audits, affirmative action and job descriptions. / Dissertation (MCom (Human Resources Management))--University of Pretoria, 2005. / Human Resource Management / unrestricted
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Die arbeidsregtelike posisie van die nakomingsbeampte in die Republiek van Suid-Afrika (Afrikaans)Koen, Gerhardus Johannes 17 August 2004 (has links)
No abstract available / Dissertation (LLM (Mercantile Law))--University of Pretoria, 2005. / Mercantile Law / unrestricted
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Die voorkoms van politieke mites in openbare beleid met spesifieke verwysing na die I am an African toespraak van T M Mbeki (Afrikaans)Rossum, Estelle 19 August 2004 (has links)
In policy studies the analysis of political myths represents both a relevant and essential investigative field. As political symbols myths have the potential to transmit ideological content in the policy discourse and to influence the social construction of reality within political communities. The purpose of this study is, therefore, to gain better understanding of the role of political myths within the context of public policy in South African. However, the impact of political myths on public policy, and the function which these political symbols fulfil within policy discourse, represent an ‘invisible’ dimension in the public policy sphere. The study of political myths therefore poses methodological challenges to the policy analyst. The prevailing positivist-orientated research tradition in policy studies does not provide the necessary analytical tools for the investigation of political myths. Analysts are, therefore, compelled to draw support from analytical contributions offered by other study fields in this regard, especially those tendered by the discourse analysis. In this dissertation an archetypal and deconstruction approach is used to analyse the I am an African-speech of T.M. Mbeki as political myth. The functional role of I am an African as political mythology in the South African policy context is investigated with reference to State of the Nation Addresses delivered at the Opening of Parliament during the period 1997 to 2001, in which national policy programmes were announced. / Dissertation (M (Political Science))--University of Pretoria, 2005. / Political Sciences / unrestricted
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An investigation into the state of affairs and sustainability of the Emfuleni economySlabbert, T.J.C. (Tielman Johannes Christian) 19 August 2004 (has links)
In this study, the sustainability of the Emfuleni economy is measured in terms of its ability to reduce the levels of unemployment and poverty over a period of time. An input-output model was used to determine the impact of several proposed projects on the level of household income and employment in Emfuleni. An economic impact assessment model was developed and used to measure the impact of a change in household income on the level of poverty. A sectoral analysis of the economy and a household analysis were used to portray the state of affairs and trends in unemployment and poverty. Taking into account both the positive impact of proposed projects and some negative impacts (e.g. the collapse of the Krion Financial scheme), projections were made for Emfuleni in terms of GGP growth, population growth, unemployment and poverty until 2015. Assuming that the two proposed projects in Emfuleni, namely, the Vaal Inland Waterfront Project and a 5% expansion of the Manufacturing sector should materialise, the analysis shows that the unemployment rate will be 53.1% in 2015 and the percentage of households below their respective poverty lines 46.6%. Without the projects the unemployment rate will increase from 51.3% in 2000 to 60.6% in 2015 and the percentage of households below their respective poverty lines will increase from 46.1% in 2000 to 60.6% by 2015. The impact of the projects will be that the unemployment and poverty rates are kept at about the same levels as in 2000. However, the analysis shows that the number of unemployed persons is expected to increase from 155,988 in 2000 to 243,660 in 2015 and the number of poor households is expected to increase from 84,549 in 2000 to 114,227 in 2015. More interventions are therefore required to put the Emfuleni economy on the road towards sustainability. An Inward Industrialisation Process (IIP) aimed at employment creation and poverty alleviation is proposed for intervention. A preliminary analysis indicates that an IIP, focussed on the townships of Emfuleni, may reduce the unemployment and poverty levels substantially and thus increase the sustainability of the economy over a period of time. / Thesis (DCom (Economics))--University of Pretoria, 2005. / Economics / unrestricted
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