258 research outputs found
Deepening democracy and enhancing multi-level governance: deficiencies of and prospects for local government ward committees in South Africa
The South African local government system has a number of shortcomings, two of which relate to the role of local government in the deepening of participatory democracy and the position of local government in a system of multi-level governance. In this article, it will be posited that a lack of depth and quality in local democracy compromises the system of intergovernmental relations. Against this background, views on participatory democracy as a theoretical background will be investigated and the development and deficiencies of the ward committee system considered. In order to contextualise the mechanism of local participation, selected international examples of public participation will be considered and an indication of the negative and positive aspects of these cases given. The South African system of intergovernmental relations will be investigated in order to show the importance of local government and public participation therein. Thereafter, suggestions will be made regarding the improvement of public participation in local government in order to adhere to the requirements of democracy and, as a result, to enhance and legitimise the system of intergovernmental relations
A test of the nitrogen-fixing ability of three agroforestry tree legumes, Tagasaste (Chamaecytisus palmensis), Port Jackson (Acacia saligna) and Sesbania sesban, when inoculated with three rhizobial strains
Diffusion effects in rotating rotary kilns
A novel approach to the modeling of mass transfer in rotary kilns has been described (Heydenrych et al, 2001). It considers the mass transfer to occur by the inclusion of gas in the interparticle voids in between the particles that move concentrically with the kiln. By doing so, the rate of mass transfer was found to be dependent on bed fill and the ratio of reaction rate constant to angular velocity (k/ ). The model was found to be valid at slow to medium fast reactions. For fast reactions it under-predicted mass transfer. Therefore in this paper, the model will be extended to include diffusion effects. An additional dimensionless number is necessary then to describe the system. This can either be a Peclet number (R2/De) or a Thiele modulus (kR2/De)1/2. The solution of the 2-dimensional partial differential equations that describe the extended model gives a handle on the effect of scale-up in rotary kilns. For industrial-scale kilns, the Peclet number is large, which means that diffusion within the lower (passive) layer of the bed is unimportant for slower rates. With high reaction rates, iso-concentration lines are closely stacked near the surface of the bed, implying that it is important to model the active layer rather than the bed as a whole in these circumstances. However, the stiff differential equations are not easily solved then, and other methods of solution are advisable
Utilization patterns in some indigenous coastal forest patches in the Transkei - the role of different management practices on forest structure
Haemoperitoneum and Associated Torsion of the Testicle in the Newborn
A case of haemoperitoneum and concomitant torsion of the testes is reported - the first case in the English literature to our knowledge. The management of the case and the aetiological factors responsible for haemoperitoneum and torsion of the testes in the newborn are discussed. The role of vitamin K in the prevention of a possible subcapsular haematoma is discussed
Design, construction and commissioning of an apparatus to perform frequency response diffusivity measurements and high time-resolution ftir spectroscopy
Bibliography: leaves 142-150.The active catalytic sites of zeolites are usually situated within the micropores of the crystals. Since the size of zeolite micropores is of a similar order of magnitude to that of many molecules, the intracrystalline diffusion of reactants and products is often the step that determines both the reaction rate and selectivity. Thus, knowledge of the diffusion rates, and of the diffusional behaviour of molecules within zeolites, is of primary importance in the understanding of these phenomena. While several methods are used to measure diffusivities, most of these have limitations associated with the minimum crystal size that can be used and/or the range of diffusivities that can be measured. Other problems frequently experienced are experimental complexity and the definition of experimental conditions within a range in which the theoretical models are applicable. A powerful method for measuring diffusivities under well-defined conditions is the frequency response method, in which the pressure response to a small volume modulation in a closed system is recorded over a range of frequencies. Models have been developed to determine the diffusivity from such experiments for a variety of circumstances, including non-isothermal conditions and multiple diffusion processes. Fourier transform infra-red (FTIR) spectroscopy can be used to monitor the uptake of sorbate molecules (and hence estimate their diffusivity) in zeolites. In addition, the behaviour of these molecules at the surface, and of the functional groups of the zeolite, can be observed. These observations reveal information about the sorption and diffusional behaviour of the molecules. For a completely reproducible process (e.g. a constant frequency volume modulation), special high time-resolution methods (i.e. rapid- and step-scan) can be used. With these techniques, very rapid molecular processes can be probed.The objective of this study was to design, construct and commission an apparatus capable of measuring diffusivities using the frequency response method, and to integrate it with an FTIR spectrometer to allow the use of standard and high time-resolution spectroscopy
An investigation of land-use practices on the Agulhas Plain (South Africa), with emphasis on socio-economic and conservation issues
Biobliography : leaves 147-156.An investigation of land-use practices was undertaken on the Agulhas Plain, a species-rich area at the southern tip of Africa. Data were collected from landowners and visitors using questionnaire surveys. Further information was obtained by means of a literature search and interviews with key informants. A historical background of land use in the area is given. Although the area has been utilized since the Earlier Stone Age (>200000 years BP), the most dramatic changes to the landscape have occurred post 1850, with the large transformation of indigenous veld into cultivated lands. Four categories of farms were identified: livestock farms, fynbos farms, mixed farms and conservation farms. Livestock farms covered the largest surface area. Cereal crops cultivated on these farms provided a net income of R 918 OOO/y. Grazing provided a net income of R 7.3 million/yon cultivated land and R 2.3 million/y was attributed to indigenous veld. This latter figure highlights the importance of natural veld for grazing, but for certain vegetation types, stocking rates were above the recommended norms. Fynbos flower farms had the second largest surface area of the four categories of farms. Fynbos wildflowers were found to be the largest single agricultural sector on the Agulhas Plain, yielding an estimated net income of R 8.55 million/y. Most harvesting from the wild takes place from Acid Sand Fynbos, which is relatively common, and there appears to be potential for wildflower harvesting to be compatible with biodiversity conservation, if managed correctly. Cultivated fynbos flowers yielded a net income of R 1.5 million/y. Cultivation of land for fynbos flowers is on the increase, and pristine fynbos is primarily being targeted for this practice, thereby threatening the biodiversity of these areas. Many landowners are involved with mixed farming practices and there are a small number of conservation farms, generally situated at the coast, which rely on outside funding for their management
Environmental evaluation of proposed alternative roads to the Mohale dam
Bibliography: p. 109-111.This is an academic report submitted in partial fulfilment of the degree Master of Environmental Science. It is written to demonstrate the competence of the writer in undertaking work in the field of Environmental Impact Assessment. The main purpose of the report is the comparative evaluation of two proposed alternative roads, the "Western Access Route" (WAR) and the "Least Cost Alternative Route" (LCAR). Since this is an academic report, it will not be used as a decision-making document and it will not be submitted to the proponent of the alternative roads
A climatology of the coastal low in the SW Cape
Bibliography: leaves 103-109.The Coastal Low is a shallow cyclonic mesoscale weather 'disturbance' which migrates around the southern African subcontinent on a fairly regular basis. It is generated and maintained by the synoptic scale circulations. The movement and surface characteristics have been well documented by a number of authors but few detailed studies have been undertaken on its vertical structure in southern Africa. In addition to this, most of the previous work has been of a meteorological nature. This study has concentrated on a more climatic approach in its investigation of the vertical and· surface features of the Coastal Low as it migrates through the South Western (SW) Cape. The SW Cape is a 'transition region' for the migration of the Coastal Low; situated between the west and south coasts with a distinct local climate due to the complex topography of the region. This fact tends to alter the characteristic features of the Coastal Low system but appears not to prevent the Coastal Low from migrating through the region. The Coastal Low is regarded as being an internal trapped Kelvin wave and corrected surface pressure values best indicate its migration characteristics. However upper air analysis indicates that temperature values (between 950- 900mb) at the level of the inversion, produce one of the best signatures of the Coastal Low's passage. This is related to the strong subsidence from above the 850mb level in the pre-Low period. This strong divergence dynamically compresses the lower layers into low level wind speed maxima on either side of the centre of the system. The Coastal Low appears to have a very complex structure, and two results from this study in the. SW Cape bear particular mention. Firstly the offshore flow at the escarpment level is weakly defined. Secondly also, the longshore spatial extent of the Coastal Low system has been estimated to have an 'inner' diameter of 150-200km and an 'outer' diameter of approximately 1000km
Eviscerated corneas as tissue source for ex vivo expansion of limbal epithelial cells on platelet-rich plasma gels
Purpose/Aim of the study: To assess if corneal epithelium can be cultured ex-vivo from corneas eviscerated due to irretrievable trauma, according to a cell culture method which made use of autologous platelet-rich plasma (A-PRP) as culture substrate. To compare corneal epithelium cultured ex vivo from corneas eviscerated following trauma using A-PRP combined with DMEM (Dulbecco's modified Eagles medium), versus DMEM alone. Materials and Methods: This was a laboratory case controlled study of human corneal cells cultured in a mixture of A-PRP and DMEM, versus DMEM alone from 6 eviscerated corneas. A hundred explants were created of which fifty explants were plated on A-PRP-gel construct combined with DMEM and fifty controls were placed in serum free DMEM alone. Donor patients received systemic antibiotics prior to evisceration. Results: Confluent epithelium in mono-layers could be cultured when donor limbal biopsies were placed in a mixture of A-PRP culture medium and DMEM. No growth were observed when corneas were placed in serum-free DMEM medium only (p<0.05). No bacterial infection was observed in cultures. Conclusions: This study demonstrated that autologous platelet rich plasma is a viable and effective alternative to bovine serum for the ex-vivo expansion of limbal epithelial cells. It also shows that eviscerated corneas are a viable source of donor tissue for this purpose in South Africa where access to tissue banks is limited
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