Radiating Collapse with Vanishing Weyl stresses

In a recent approach in modelling a radiating relativistic star undergoing gravitational collapse the role of the Weyl stresses was emphasised. It is possible to generate a model which is physically reasonable by approximately solving the junction conditions at the boundary of the star. In this paper we demonstrate that it is possible to solve the Einstein field equations and the junction conditions exactly. This exact solution contains the Friedmann dust solution as a limiting case. We briefly consider the radiative transfer within the framework of extended irreversible thermodynamics and show that relaxational effects significantly alter the temperature profiles.Comment: 10 pages, submitted to IJMP-

Advancing the hygiene management system at poultry abattoirs in Gauteng, South Africa

Published ArticleThe Meat Safety Act, Act 40 of 2000 compels all registered abattoirs in South Africa to implement and maintain a Hygiene Management System (HMS) to ensure the safe processing of meat. The HMS is a basic food safety system that focuses on process standards that are designed to reduce the risk of contamination of meat and meat products during processing. Part of the Poultry regulations provide the requirements of HMS and were published by government on the 24th of February 2006. However, no guidelines were published or made available to poultry abattoir operators on how to interpret and implement the requirements of the HMS. The aim of this research was to determine the extent of HMS implementation at poultry abattoirs in Gauteng. The intention was to identify short comings, if any, within implemented HMSs with the intention of promoting compliance. This was achieved by developing common themes from research audit findings. These themes were then used to suggest critical areas that should be addressed during the development of an HMS implementation guideline document

A microbiological survey of fresh meat processed at abattoirs in Gauteng, South Africa

Published ArticleThe abattoir Hygiene Management System (HMS) was regulated in South Africa under the Meat Safety Act 40 of 2000. Presently, there is no national regulated microbiological standard to compare against meat tested at abattoirs as an indicator of good hygiene practices. The aim of the study was to establish a provincial guideline for a microbiological baseline. This may be used to verify the performance of the implemented HMS. Thirty red meat and twenty-two poultry abattoirs were sampled to determine baseline Total Bacterial Counts (TBCs). The results of this study were compared to standards presently used in the United Kingdom (UK). The results compared favourably

Inflation driven by causal heat flux

We find a simple inflationary solution in an inhomogeneous spacetime with heat flux. The heat flux obeys a causal transport equation, and counteracts the inflationary decrease of energy density. At late times, the heat flux tends to zero and the fluid approaches the equation of state $p=-\rho$.Comment: Latex 5 pages; to appear Gen. Rel. Gra

Antibiotic susceptibility patterns of Neisseria gonorrhoeae isolates in Port Elizabeth

Objective: To survey the antibiotic susceptibility of Neisseria Gonorrhoeae isolates. Design: This was a cohort analytical study.Setting Three clinics serving different areas in Port Elizabeth.Outcome measures Prevalence of antibiotic-resistant N. gonorrhoeae isolates. Results: Twenty-one of the 35 isolates (60%) were resistant to ciprofloxacin, while 28 (80%) showed resistance to erythromycin, 17 (48.6%) to penicillin, 3 (8.6%) to doxycycline, 11 (31.4%) to spectinomycin and 33 (94.3%) to tetracycline.Conclusion: To ensure effective treatment of gonorrhoea, continued surveillance of antimicrobial susceptibility is necessary.South African Medical Journal Vol. 96(3) 2006: 225-22

Radiating spherical collapse with heat flow

We present here a simple model of radiative gravitational collapse with radial heat flux which describes qualitatively the stages close to the formation of a superdense cold star. Starting with a static general solution for a cold star, the model can generate solutions for the earlier evolutionary stages. The temporal evolution of the model is specified by solving the junction conditions appropriate for radiating gravitational collapse.Comment: 13 pages, including 3 figures, submitted to IJMP-

Relaxational effects in radiating stellar collapse

Relaxational effects in stellar heat transport can in many cases be significant. Relativistic Fourier-Eckart theory is inherently quasi-stationary, and cannot incorporate these effects. The effects are naturally accounted for in causal relativistic thermodynamics, which provides an improved approximation to kinetic theory. Recent results, based on perturbations of a static star, show that relaxation effects can produce a significant increase in the central temperature and temperature gradient for a given luminosity. We use a simple stellar model that allows for non-perturbative deviations from staticity, and confirms qualitatively the predictions of the perturbative models

The marine linefish resources of Moçambique (status, development and future research)

Marine line-fishing is seen to be of major importance to the social well-being and economy of many coastal people of Mozambique. Aspects of the artisanal and semi-industrial fisheries of Mozambique are described and a recent significant increase in effort is noted. Landings are seen to comprise a high proportion of vulnerable, endemic species, several of which are shared with neighbouring South Africa. Trends in CPUE, sex ratios and yield per recruit suggest that future landings may decline if conservative management is not introduced. Strategies for data collection and biological research on key species are proposed

Mainstreaming Underutilized Indigenous and Traditional Crops into Food Systems: A South African Perspective

Business as usual or transformative change? While the global agro-industrial food system is credited with increasing food production, availability and accessibility, it is also credited with giving birth to ‘new’ challenges such as malnutrition, biodiversity loss, and environmental degradation. We reviewed the potential of underutilized indigenous and traditional crops to bring about a transformative change to South Africa’s food system. South Africa has a dichotomous food system, characterized by a distinct, dominant agro-industrial, and, alternative, informal food system. This dichotomous food system has inadvertently undermined the development of smallholder producers. While the dominant agro-industrial food system has led to improvements in food supply, it has also resulted in significant trade-offs with agro-biodiversity, dietary diversity, environmental sustainability, and socio-economic stability, especially amongst the rural poor. This challenges South Africa’s ability to deliver on sustainable and healthy food systems under environmental change. The review proposes a transdisciplinary approach to mainstreaming underutilized indigenous and traditional crops into the food system, which offers real opportunities for developing a sustainable and healthy food system, while, at the same time, achieving societal goals such as employment creation, wellbeing, and environmental sustainability. This process can be initiated by researchers translating existing evidence for informing policy-makers. Similarly, policy-makers need to acknowledge the divergence in the existing policies, and bring about policy convergence in pursuit of a food system which includes smallholder famers, and where underutilized indigenous and traditional crops are mainstreamed into the South African food system