The Effect of Diffusion on the Particle Spectra in Pulsar Wind Nebulae

A possible way to calculate particle spectra as a function of position in pulsar wind nebulae is to solve a Fokker-Planck transport equation. This paper presents numerical solutions to the transport equation with the processes of convection, diffusion, adiabatic losses, and synchrotron radiation included. In the first part of the paper the steady-state version of the transport equation is solved as a function of position and energy. This is done to distinguish the various effects of the aforementioned processes on the solutions to the transport equation. The second part of the paper deals with a time-dependent solution to the transport equation, specifically taking into account the effect of a moving outer boundary. The paper highlights the fact that diffusion can play a significant role in reducing the amount of synchrotron losses, leading to a modification in the expected particle spectra. These modified spectra can explain the change in the photon index of the synchrotron emission as a function of position. The solutions presented in this paper are not limited to pulsar wind nebulae, but can be applied to any similar central source system, e.g. globular clusters

Revised food-based dietary guidelines for South Africa: challenges pertaining to their testing, implementation and evaluation

No Abstract

Dietary patterns and nutrient intakes of a South African population and asymptomatic people infected with Human Immunodeficiency Virus: The transition health and urbanisation in South Africa (Thusa) study

There is increased emphasis on the quality of food and the overall pattern of micronutrient intake as an integral consideration for food security particularly among people living with HIV/AIDS (PLWHA). However, limited data exist on food consumption and nutrient intakes for populations in sub-Saharan Africa. The study examined dietary patterns and their relationship with nutrient intakes in HIV uninfected (HIV-) and infected (HIV+) adults in North-West Province, South Africa. In this cross-sectional study, dietary and nutrient intakes were assessed with Quantitative Food Frequency Questionnaire (QFFQ) and FoodFinder software, respectively. Dietary patterns were determined using Principal Component Analysis. Participants’ scores for the dietary patterns were related to nutrient intakes using Spearman Rank correlation and Generalised Linear Modelling (GENLIN). Four main dietary patterns were found in each population. The first three patterns were similar between the HIV- and HIV+ populations: “animal-based”, associated with intake of foods of animal origin; “recommended” associated with a varied diet; and “staple-based”. The fourth pattern was described as either ‘eggs-and-breakfast-cereals’ for the HIV- group or ‘legumes-and-vegetables’ for HIV+ group. Scores for animal-based pattern showed strongest correlations (r) with nutrient intakes for both populations, notably zinc (r=0.54), calcium (r=0.5), potassium (r=0.54), vitamin A (r=0.5), and vitamin C (r=0.5), (p<0.001 for all). In the HIV+ group, the legumes-and-vegetables pattern was strongly associated with energy (r=0.64), vitamins D (r=0.51), E (0.51) and B1 (r=0.55) (p<0.001 for all). Compared with the other patterns, the Staple-based and the recommended patterns showed the weakest associations with nutrient intakes. Generalised Linear Modelling confirmed stronger positive linear associations between scores of the animal-based diet and nutrients intake, compared with the other patterns. The findings suggest that the animal-based pattern was strongly associated with nutrients intake in both HIV + and HIV- populations. This raises the need for studies into dietary recommendations for promoting nutritional wellbeing for PLWHA in sub-Saharan Africa.Keywords: Dietary patterns; HIV/AIDS; THUSA, Nutrient

Nutrient intake and consumption of indigenous foods among college students in Limpopo Province

Objective. To determine the habitual diet and the consumption of indigenous foods among college students in Limpopo province. Design. The sample consisted of 37 healthy student volunteers (18 males and 19 females) aged 23.3 ±2.38 years, with a body mass index of 22.7 ±2.32 kg/m2. A validated quantitative food frequency questionnaire was used to collect information on the habitual diet of the participants. Nutrient analysis was done using FoodFinder. Results. Mean dietary intakes were 10 042 kJ, 16.3% protein energy, 28.9% fat energy and 54.8% carbohydrate energy for females, and 12 050 kJ, 16.7% protein energy, 26.4% fat energy and 56.9% carbohydrate energy for males. The contribution of fat, carbohydrate and protein to total energy intake was similar for males and females. Frequency of food item consumption varied among students with indigenous foods consumed less often. Consumption of indigenous foods was similar in male and female subjects. Conclusion. The habitual diet of the college students was estimated, and compared favourably with other reported data. However, patterns of indigenous food consumption were difficult to estimate. Although the number of indigenous foods used was high at 28 of 60 food items, consumption in terms of both quantity and the total number of students consuming these foods was low. Further studies are needed to determine the patterns of indigenous food intake and the contribution of these foods to total nutrient intake. South African Journal of Clinical Nutrition Vol. 18 (1) 2005: 32-3

Impact of urbanisation on Serum lipid profiles -the thusa survey

Objective. To examine the impact of urbanisation on lipid profiles of black South Africans, stratified for HIV status.Design. Cross-sectional population-based survey.Setting. North West province of South Africa.Subjects. A representative sample of 1854 apparently healthy volunteers aged ≥ 15 years, was recruited from 37 randomly selected sites throughout the province. Subjects were stratified into five urbanisation strata (S): Sl rural villages, S2 farms, S3 informal housing or 'squatter camps', S4 urban townships, and S5 surburban housing.Outcome measures. Demographic, physical activity and dietary intake information was collected using validated and culture-sensitive questionnaires. Anthropometric measurements and lipid analyses were determined using standardised methodology.Results. The results revealed significantly lower mean(95% confidence interval) total serum cholesterol (TC) levels in HIV-negative men in Sl -S4 compared with S5 (S1 3.91 (3.77- 4.05) v. S5 4.79 (4.54- 5.04) mmol/1). In HIV-negative women, TC levels were significantly lower in Sl - S3 than in S4 and S5 (S1 4.05 (3.94- 4.17) v. S5 4.79 (4.59- 5.00) mmol/1). The same trends were seen for serum low-density lipoprotein cholesterol (LDLC) and triglycerides and in HIV-positive subjects. Binary logistical analysis indicated that the main factor responsible for the increased TC levels seemed to be increased body mass index (BMI) due to decreased physical activity. Conclusions. Serum lipid levels increased with urbanisation although they remained within levels recommended for ther populations. This may, however, become an important health problem in future if preventive strategies are not implemented. Culturally sensitive physical activity programmes to decrease BMI, targeted at professional me and women, and women in urban townships, seem to constitute the most appropriate intervention

Modern considerations when approaching fractured endodontic instruments - Part 2: A review of the literature and clinical techniques

Once root canal treatment is considered, the treating clinicians must be aware of the real possibility that complications and unforeseen accidents can occur during any stage of the treatment. Complications and accidents may include instrument separation, root perforation on different levels and ledge formation

Functional foods with added plant sterols for treatment of hypercholesterolaemia and prevention of ischaemic heart disease

Background. A spread with added plant sterols, Pro-activ, is marketed in South Africa as an adjunct to low-fat diets for lowering of total and low-density lipoprotein (LDL) cholesterol concentrations and to decrease risk of ischaemic heart disease (IHD). Objectives. The need for this functional food in South Africa, its efficacy, safety and target market, are evaluated in this review. Results. The high, and probably increasing incidence of hypercholesterolaemia and cardiovascular disease in South Africa motivates the need for appropriate functional foods. There is convincing evidence in the literature that an average daily intake of about 2 g plant sterols in about 20 g of spread significantly lowers total and LDL cholesterol concentrations by approximately 10 - 15%, without influencing high-density lipoprotein (HDL) cholesterol and triglyceride concentrations. There is some concern about the effects on absorption of lipid-soluble vitamins and pro-vitamins, but safety tests lasting for up to 3 years found no serious adverse effects. Conclusions. The target market for this spread should be nonpregnant, non-lactating adults with hypercholesterolaemia and/or increased risk of IHD. If it is considered for use in hypercholesterolaemic children, fat-soluble vitamin status should be monitored. It is recommended that post-marketing surveillance should be established to determine long-term effects and safety

Factors facilitating sustainable scientific partnerships between developed and developing countries

International scientific partnerships are key to the success of strategic investments in plant science research and the farm-level adoption of new varieties and technologies, as well as the coherence of agricultural policies across borders to address global challenges. Such partnerships result not only in a greater impact of published research enhancing the career development of early and later stage researchers, but they also ensure that advances in plant science and crop breeding technologies make a meaningful contribution to society by brokering acceptance of emerging solutions to the world problems. We discuss the evidence showing that despite a lack of funding, scientists in some African countries make a significant contribution to global science output. We consider the criteria for success in establishing long-term scientific partnerships between scientists in developing countries in Southern Africa (“the South”) and developed countries such as the UK (“the North”). We provide our own personal perspectives on the key attributes that lead to successful institutional collaborations and the establishment of sustainable networks of successful “North-South” scientific partnerships. In addition, we highlight some of the stumbling blocks which tend to hinder the sustainability of long-term “North-South” scientific networks. We use this personal knowledge and experiences to provide guidelines on how to establish and maintain successful long-term “North-South” scientific partnerships.National Research Foundation of South Africa, Winter Cereal Trust and African Union Research Grant Programme funded by the European Union.http://journals.sagepub.com/home/oaghj2021Forestry and Agricultural Biotechnology Institute (FABI)Plant Production and Soil Scienc

Socio-economic and social capital assessment of Avian Park residents, Worcester

At the beginning of every academic year, the Department of Sociology and Social Anthropology (hereafter Department), Stellenbosch University, takes Honours students on a research fieldtrip. The rationale is based on the need to provide Honours students with an in-service learning opportunity that entails fieldwork in an environment where their research efforts could make a contribution to community development. There is thus a dual objective: firstly, in-service learning through applied research using different research methodologies and secondly, the generation of new knowledge that could benefit community initiatives of various stakeholders. There is an additional third objective, namely to train community members in fieldwork skills in order for them to partake in similar studies. For 2011 Worcester and more specifically Avian Park (ward 13) was chosen as the research site. This site was selected partly because Stellenbosch University already has a community health project running in this area and there was both an interest and need for collaboration from the side of the Ukwanda Rural Clinical School in Worcester. Other University stakeholders included (in alphabetical order): Family Medicine, Human Nutrition, Occupational therapy, Physiotherapy, Speech, Language and Hearing therapy, Rehabilitation and Social Work. These stakeholders desired information about the community and some wanted to use the community volunteers trained by the Department for future research projects/interventions in the community