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The subject of 'independence' of the South African Broadcasting Corporation (SABC) has emerged as a key issue in post-apartheid South African public discourse. While the importance of 'independence' has rarely been questioned, the term's meaning has been subject to fragmented understandings and vague interpretations. This thesis explores the origins of divergent conceptions of 'independence', examining how these conceptions are constructed by staff within the SABC. The central task of this thesis is to critically examine the contested concept of 'independence' a task it accomplishes by engaging with issues of power, knowledge and identity. To this end, the thesis reveals that the neo-liberal policies imposed by the Washington Consensus play a significant role in shaping conceptions of 'independence' through their power to dictate policy in countries in the Global South, including South Africa. This power, exercised through dominant Washington Consensus institutions, such as the World Bank and the International Monetary Fund (IMF), inform knowledge and identities at a local level through the adoption of neo-liberal macro-economic strategies, such as Growth Employment and Redistribution (GEAR). As a result, there is no local without the global. The engagement with issues of power, identity and knowledge and their relationships to how 'independence' is understood ensures that meanings of 'independence' are contested and that 'independence' is not an immovable edifice. 'Independence' is only a product of an evolving matrix, in which the staff of the SABC, who are divided into four different tiers, construct their own interpretations of 'independence', shaped by their understandings of both organisational and external factors, such as politics and advertisers, in relation to their work. Using data from interview respondents and an analysis of key public policy documents, this thesis presents two key processes that influence understandings of 'independence' and, therefore, link the SABC to the larger external socio-political environment. These two key factors, the commercialisation of the SABC and the African National Congress (ANC) power struggles have helped to shape the four conceptions of 'independence' advanced in this thesis: namely, the legalistic, anti-establishment, political and professional conceptions of 'independence'. At the core of this thesis are two questions: How do staff within the SABC construct and understand the meaning of 'independence' of the SABC, and what has influenced these conceptions in post-apartheid South Africa? Consistent with these research questions, the thesis is located within the interpretive tradition, since it seeks to understand the world of the SABC through the lens of its staff. To complement the interpretivist approach, the thesis situates the SABC and its understandings of 'independence' within the wider South African context, in which the meaning of 'independence' should also be understood as being inextricably intertwined with and a product of the shifting developmental state of the macro-economic environment. The critical political economy of the media is, therefore, used as an explanatory framework for understanding how the macro-worlds of politics and economic strategies intersect within the micro-world of the SABC to shape conceptions of 'independence'. The thesis concludes by arguing that it is not a strong and domineering state that seeks to control public service broadcasting; instead, it is a weak state that does so because of a need to curtail public discourse, which might present a threat to its own existence if left uncontrolled. As a result, it is difficult to separate the SABC from the state and, for that reason, the role of the public service broadcaster (PSB) is tied to the national narrative which itself is tied to the larger global matrices of power.

We describe the conceptual design and first application of a new method for simultaneously measuring the fluid permeability and specific storage of a rock sample. In our laboratory tests, a constant flow rate single-stroke piston pump injects fluid into a cored rock specimen placed between two reservoirs in which fluid pressure is recorded. For this geometry we have derived a new analytic solution of the governing diffusion equation describing the one-dimensional fluid flow. This new analytic solution in the time domain consists of two parts: an asymptotic linear function of time, and a transient part which decays to zero as time increases. The model predicts that the fluid pressures of the upstream and downstream reservoirs both increase linearly with time after the initial transient vanishes. The slope of the linear pressure variation depends on the specific storage of the rock sample for a given test condition, and the differential pressure between the two reservoirs is related to the permeability. If the downstream pressure is not recorded, the permeability can be calculated from the zero intercept of the linear upstream fluid pressure variation. This calculation is quite straightforward and no tedious history curve matching is required. We applied our new method to measure fluid permeability and specific storage of Westerly granite. The measured values of the permeability are consistent with those published in the literature. The main advantages of our method are the reliability of the testing method, its economy of time, and the flexibility in adapting the system parameters to tests at different conditions.

Mechanical properties of rocks are characterized by their notable dependence on the applied deformation rate. However, little is known about the strain rate dependence of fluid flow properties since most laboratory tests are conducted using a single, high strain rate. We have investigated the effect of loading rate on the permeability of porous sandstones by carrying out triaxial compression tests at four different temperatures and strain rates with continuous monitoring of permeability, acoustic emission (AE), and pore fluid chemistry. All tests are characterized by an initial permeability decrease due to inferred compaction of favorably oriented cracks. The amount of initial permeability reduction increases with decreasing strain rate, thus implying a more efficient initial compaction at slower strain rates. At a later stage of loading, permeability correlates with stress, ion concentration, or AE damage depending on the strain rate used. High strain rate tests are characterized by a positive power law or logarithmic correlation between permeability and AE damage. At slow strain rates, permeabilities decrease exponentially with mean effective stress and axial strain for the Locharbriggs sandstone. The Clashach sandstone exhibits a linear correlation between permeability and exit pore fluid concentrations (Si, Mg, Fe, Al) if a slow strain rate is used. These observations have important implications for the applicability of room temperature, high strain rate laboratory data to the conditions that prevail in the Earth's crust.

Triaxial deformation experiments were carried out on large (0.1 m) diameter cores of a porous sandstone in order to investigate the evolution of bulk sample permeability as a function of axial strain and effective confining pressure. The log permeability of each sample evolved via three stages: (1) a linear decrease prior to sample failure associated with poroelastic compaction, (2) a transient increase associated with dynamic stress drop, and (3) a systematic quasi-static decrease associated with progressive formation of new deformation bands with increasing inelastic axial strain. A quantitative model for permeability evolution with increasing inelastic axial strain is used to analyze the permeability data in the postfailure stage. The model explicitly accounts for the observed fault zone geometry, allowing the permeability of individual deformation bands to be estimated from measured bulk parameters. In a test of the model for Clashach sandstone, the parameters vary systematically with confining pressure and define a simple constitutive rule for bulk permeability of the sample as a function of inelastic axial strain and effective confining pressure. The parameters may thus be useful in predicting fault permeability and sealing potential as a function of burial depth and fault displacement.

Saliva has been recommended as a safe and effective alternative to serum for enzyme-linked immunosorbent assay (ELISA) for HIV antibodies in surveillance programmes in developing countries. We evaluated the use of saliva specimens for detection of HIV antibodies using three different commercially available ELISAs. Saliva specimens from 107 patients selected at random from HIV high-risk (38), medium-risk (27) and low-risk (42) areas of the hospital were screened with the Wellcozyme HIV1 + 2 GACELISA VK61 (recommended for use with saliva), Wellcozyme HIV1 + 2 VK54/55 and Wellcozyme HIV-1 recombinant VK56/57. Of the 107 patients, 50 were positive and 57 negative for antibodies to HIV on confirmatory Western blot testing. For detection of antibodies to HIV in saliva, the Wellcozyme HIV1 + 2 GACELISA VK61 had a sensitivity and a specificity of 98%, the Wellcozyme HIV-1 recombinant VK56/57 a sensitivity and specificity of 96%, and the Wellcozyme HIV1 + 2 VK54/55 a sensitivity of 94% and a specificity of 95%. For detection of antibodies to HIV in serum, the Wellcozyme HIV-1 recombinant VK56/57 had a sensitivity and a specificity of 100%, the Wellcozyme HIV1 + 2 GACELISA VK61 a sensitivity and a specificity of 98%, and the Wellcozyme HIV1 + 2 VK54/55 a sensitivity and a specificity of 96%. This study illustrates that saliva can be used as an alternative to serum for screening for anti-HIV antibodies in African patients.

The time-dependent properties of ceramic materials such as rocks depend both on preexisting cracks and chemical properties acting at their tips. We have examined the direct effect of chemical processes on the growth of a crack population by carrying out triaxial flow-through compression tests on Locharbriggs sandstone. The tests were carried out at temperatures of 25–80°C and at strain rates ranging from 10−5 to 10−8 s−1 under constant stress rate loading. The exit pore fluid was analyzed after the tests for the concentration of dissolved ions and acoustic emission was monitored in real time throughout the tests. The exit pore fluid silica concentration and microcrack damage derived from the acoustic emission (AE) data both exhibited an exponential increase during the strain hardening phase of deformation. Damage parameters inferred from the AE data predict the stress-strain curves adequately, or at least up to the point of strong microcrack coalescence. The damage parameters and silica signal were strongly correlated by a power law relationship. The observed environment and strain rate dependence of mechanical properties can hence be attributed uniquely to time-dependent crack growth by the stress corrosion mechanism.

We undertook a nine month study to define the frequency of parasitic infections in adults with diarrhoea presenting at the medical filter clinic and the Dermatovenereology clinic of the University Teaching Hospital in Lusaka, Zambia. A total of 287 patients with diarrhoea were enrolled in the study; 130 from the adult medicine filter clinic recruitment consulting room and 157 patients from the Dermatovenereology clinic. Of 130 patients from the adult filter clinic, 85 (65%) were HIV-seropositive and 45 (35%) were seronegative for HIV. Out of 85 HIV-seropositive patients, 58 (68.2%) had acute diarrhoea and 27 (31.8%) had chronic diarrhoea. Of the 45 HIV-seronegative patients, 35 (77%) had acute diarrhoea and 10 (23%) had chronic diarrhoea. All of the 157 patients recruited from the Dermatovenereology clinic were HIV-seropositive. Of these, 97 (62%) had chronic diarrhoea; 7 (4%) had acute diarrhoea, and 53 (34%) patients had no diarrhoea. The common parasites detected were Ascaris lumbricoides, hookworm, Entamoeba coli, and Cryptosporidium spp. Isospora belli and Cryptosporidium spp were seen only in the HIV-seropositive group. In the Dermatovenereology clinic there was a statistically significant difference between parasite detection rate of Isospora belli and Cryptosporidium spp in HIV-seropositive patients with chronic diarrhoea compared to asymptomatic HIV-seropositive individuals P0.01 and p = 0.05, respectively). A significant difference in detection rates of Entamoeba coli was seen between the HIV-seropositive group in the Dermatovenereology clinic [17 (10.8%) out of 157] compared to 1 (1.5%) out of 85 in the adult medicine filter clinic.(ABSTRACT TRUNCATED AT 250 WORDS)Over a period of 9 months (June 1, 1992-February 25, 1993), a total of 287 patients with diarrhea presenting at the adult medicine filter clinic (130) and the dermatovenereology clinic (157) of the University Teaching Hospital in Lusaka, Zambia, were enrolled in a study of the frequency of parasitic infections in adults with diarrhea. All of the 157 patients recruited from the dermatovenereology clinic were HIV-seropositive. Of these, 97 (62%) had chronic diarrhea; 7 (4%) had acute diarrhea, and 53 (34%) had no diarrhea. Out of 130 patients recruited from the adult medicine filter clinic, 85 (65.4%) were HIV-seropositive and 45 (34.6%) were seronegative. Of the HIV-seropositive patients, 58 (68%) had acute diarrhea and 27 (32%) had chronic diarrhea. 10 (23%) of the HIV-seronegative patients had chronic diarrhea. The common parasites detected in stools of all HIV-seropositive adults were Ascaris lumbricoides, hookworm, Entamoeba coli, and Cryptosporidium spp. The coccidian parasites Isospora belli and Cryptosporidium spp were seen only in the HIV-seropositive group. In the dermatovenereology clinic there was a statistically significant difference between parasite detection rate of Isospora belli and Cryptosporidium spp in HIV-seropositive patients with chronic diarrhea compared to asymptomatic HIV-seropositive individuals (p = 0.01 and p 0.05, respectively). Cryptosporidium was detected in 4 (4.7%) HIV-seropositive adults in the adult medicine filter clinic and in 4 (4%) seropositive patients with diarrhea in the dermatovenereology clinic. Isospora belli was detected in 5 (6%) HIV-seropositive adult medicine filter clinic patients, while 9 (9%) HIV-seropositive patients from the dermatovenereology clinic had this parasite. A significant difference in detection rates of Entamoeba coli was seen between the HIV-seropositive group in the dermatovenereology clinic: 17 (10.8%), compared to patients in the adult medicine filter clinic: 1 (1.5%).