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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Fuelwood harvesting and selection in Valley Thicket, South Africa

Pote, J, Shackleton, C.M., Cocks, M.L., Lubke, R. 10 1900 (has links) (PDF)
The Thicket Biome is the second smallest biome in South Africa, and is renowned for its high biodiversity. Yet, less than 5% of the biome is in formal conservation areas. Much of the currently intact thicket outside protected areas is threatened by land transformation to commercial agriculture or heavy use by rural communities. There is limited understanding of the ecological structure and function of thicket communities and their response to these human pressures. This paper reports on a study to characterize the woody communities in Valley Thicket and Thornveld surrounding a rural village. We also examined the demand and selection for specific woody species. There was a marked selection for key species for different uses, including fuelwood, construction timber, and cultural stacks. There was also strong selection for specific size classes of stem, especially those between 16–45 cm circumference. The density, biomass and species richness of woody species was reduced close to the village, and increased with distance away from human settlement. A similar trend was found for the basal area of preferred species, but not for the basal area of all species. The strong selectivity for both species and size class means that the anthropogenic impacts are not uniform within the woody strata, leading to marked changes in community structure and floristics at a local scale.
152

Water resources in Botswana with particular reference to the savanna regions

du Plessis, A.J.E., Rowntree, K.M. January 2003 (has links) (PDF)
Production and development in the savanna regions of southern Africa are primarily determined by interactions between the limitations imposed by ecological determinants (such as rainfall and soil quality) and the management strategies of the specific region. Good planning, focussing on both the short and long-term effects of water use, is needed in water management strategies. Botswana is already experiencing so-called 'water stress' which is related to a number of factors such as rapidly increasing population leading to a sharp increase in water demand, low and variable rainfall, high rates of evaporation, and the high cost of exploiting existing water resources. At the current rates of abstraction, the lifetime of surface and groundwater resources is limited to decades. Botswana shares four river basins with its neighbouring countries. This results in a situation where 94% of the fresh water resources which Botswana can theoretically access originates outside its borders, making water resource management highly complex. Transnational sharing and management of water resources, therefore, plays a major role in securing sustainability of this precious resource.
153

The complexities of media regulation

Banda, Fackson 31 August 2006 (has links) (PDF)
This is a review of Article 19's publication entitled 'Broadcasting pluralism and diversity: training manual for African regulators'. It analyses the key issues raised in the manual, and problematises them in terms of media theory. It concludes that the Article 19 manual is a useful training resource, regardless of some of its theoretical and presentational shortcomings.
154

The thermal decomposition of copper(II) oxalate revisited

Lamprecht, E., Watkins, G.M., Brown, M.E. 01 July 2006 (has links) (PDF)
DSC, TG and TG-FT-IR, and XRPD have been used to examine the effects of supposedly inert atmospheres of argon and nitrogen on the mechanism of the thermal decomposition of copper(II) oxalate. The DSC curves in pure argon at 10 °C min[superscript −1] show a broad endotherm with onset at about 280 °C and maximum at about 295 °C. In mixtures of argon and nitrogen, as the proportion of argon gas is decreased, the endothermic character of the decomposition decreases until, when nitrogen is the main component, the decomposition exhibits a complex broad exothermic character. XRPD studies showed that, regardless of the proportions of nitrogen and argon, the DSC residues consisted of mainly copper metal with small amounts of copper(I) oxide (cuprite) and, under some conditions, traces of copper(II) oxide (tenorite). Various explanations for this behaviour are discussed and a possible answer lies in the disproportionation of CO[subscript 2](g) to form small quantities of O[subscript 2](g) or monatomic oxygen. The possibility exists that the exothermicity in nitrogen could be explained by reaction of the nitrogen with atomic oxygen to form N[subscript 2]O(g), but this product could not be detected using TG-FT-IR.
155

Novel amperometric glucose biosensor based on an ether-linked cobalt(II) phthalocyanine–cobalt(II) tetraphenylporphyrin pentamer as a redox mediator

Ozoemena, K.I., Nyokong, T. 15 July 2006 (has links) (PDF)
The development of cobalt(II) phthalocyanine–cobalt(II) tetra(5-phenoxy-10,15,20-triphenylporphyrin), (CoPc–(CoTPP)[subscript 4]) pentamer as a novel redox mediator for amperometric enzyme electrode sensitive to glucose is described. A glassy carbon electrode (GCE) was first modified with the pentamer, then followed by the immobilization onto the GCE–CoPc–(CoTPP)[subscript 4] with glucose oxidase (GOx) through cross-linking with glutaraldehyde in the presence of bovine serum albumin (BSA) and Nafion® cation-exchange polymer. The proposed biosensor displayed good amperometric respose charateristics to glucose in pH 7.0 PBS solution; such as low overpotentials (+400 mV versus Ag|AgCl), very fast amperometric response time (~5 s), linear concentration range extended up to 11 mM, with 10 μM detection limit. The biosensor exhibited electrochemical Michaelis–Menten kinetics and showed an average apparent Michaelis–Menten constant (K′M) of 14.91 ± 0.46 mM over a storage period of 2 weeks.
156

Automated estimation and analyses of meteorological drought characteristics from monthly rainfall data

Smakhtin, V.U., Hughes, D.A. 06 1900 (has links) (PDF)
The paper describes a new software package for automated estimation, display and analyses of various drought indices – continuous functions of precipitation that allow quantitative assessment of meteorological drought events to be made. The software at present allows up to five different drought indices to be estimated. They include the Decile Index (DI), the Effective Drought Index (EDI), the Standardized Precipitation Index (SPI) and deviations from the long-term mean and median value. Each index can be estimated from point and spatially averaged rainfall data and a number of options are provided for months' selection and the type of the analysis, including a running mean, single value or multiple annual values. The software also allows spell/run analysis to be performed and maps of a specific index to be constructed. The software forms part of the comprehensive computer package, developed earlier and designed to perform the multitude of water resources analyses and hydro-meteorological data processing. The 7-step procedure of setting up and running a typical drought assessment application is described in detail. The examples of applications are given primarily in the specific context of South Asia where the software has been used.
157

Cellulases (CMCases) and polyphenol oxidases from thermophilic Bacillus spp. isolated from compost

Mayende, L., Wilhelmi, B.S., Pletschke, B.I. 09 1900 (has links) (PDF)
In composting, organic matter is degraded by cellulases and ligninolytic enzymes at temperatures typically above 50 °C. This study isolated thermophilic microorganisms from a compost system that were then screened for cellulase and polyphenol oxidase activity. Temperature optima for the cellulases and polyphenol oxidases were determined as 70 and 40 °C, respectively. Maximal cellulase activity was determined as 1.333 mg glucose released ml[superscript −1] min[superscript −1]. Maximal polyphenol oxidase activity attained was 5.111 nmol phenol ml[superscript −1] min[superscript −1]. Cellulases were found to be stable over a period of 1 h. The isolated compost microorganisms were identified as strains of Bacillus using 16S ribosomal DNA sequence analysis.
158

Farming against the odds : an examination of the challenges facing farming and rural development in the Eastern Cape province of South Africa

Nel, E.L., Davies, J. 07 1900 (has links) (PDF)
Recent political transformation in South Africa has laid the basis for significant socioeconomic change. One area in which the greatest socioeconomic disparities are discernable is the agricultural sector and rural development in general. Through the medium of a case study of the Eastern Cape province, the obstacles and opportunities facing the two predominant farming groups —emerging black small-scale farmers and white commercial farmers — are examined. The paper concludes with an examination of the economic potential of the former ‘white' areas to sustain the resettlement of people previously excluded from that land market on racial grounds.
159

Rural self-reliance strategies in South Africa: community initiatives and external support in the former black homelands

Nel, E.L., Binns, T. 07 1900 (has links) (PDF)
This paper examines the relevance of the concept of self-reliance in the context of rural community economic development in South Africa. Whilst changing global and local circumstances oblige impoverished communities to become more pro-active in the enhancement of the quality of their lives, they nevertheless cannot ignore basic market forces and the need for an appropriate level of external assistance. Four community-based agricultural ventures in South Africa's former Homelands are examined. A comparison between the four schemes permits an assessment to be made of what such community ventures require if they are to succeed and have a meaningful impact on job creation and poverty alleviation. The role of external support agencies and access to markets in each case features prominently in the assessment.
160

The role of ‘African Chemists’ in the health care system of the Eastern Cape province of South Africa

Cocks, M.L., Dold, A.P. 16 November 2000 (has links) (PDF)
Self-medication is documented as an integral part of health care therapy in developing countries such as Ethiopia, Cameroon, Uganda and Mexico. In South Africa the types of illnesses and health problems that are referred to both traditional healers and biomedical practices have been well documented. However, very little literature exists on self-diagnosis, self-medication or sources of the medicines used for self-medication. This bias in the literature has come about largely because anthropological studies have focused on the later stages of the illness referral system when treatment is sought from a specialist for symptoms which have not responded to forms of self-medication. As a result of this, health care studies have documented the more exceptional exotic healing rituals and culturally bound syndromes of a particular society or community, and not discussed the more ordinary practices of self-medication of everyday illness. Self-medication is however an important initial response to illness and many illnesses are successfully managed at this stage. Amayeza stores (singular-iyeza store) — or ‘African chemists’ — are an important source of medicines for self-diagnosed illnesses. The current discussion focuses on the types of medicines and treatments that are obtained from amayeza stores without professional consultation in the Eastern Cape province of South Africa.

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