Scielo RSS http://www.scielo.org.za/rss.php?pid=0038-235320130005&lang=es vol. 109 num. 9-10 lang. es http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500001&lng=es&nrm=iso&tlng=es http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500002&lng=es&nrm=iso&tlng=es http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500003&lng=es&nrm=iso&tlng=es http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500004&lng=es&nrm=iso&tlng=es http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500005&lng=es&nrm=iso&tlng=es http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500006&lng=es&nrm=iso&tlng=es http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500007&lng=es&nrm=iso&tlng=es http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500008&lng=es&nrm=iso&tlng=es The University of KwaZulu-Natal is in the process of formulating a language policy to introduce teaching and learning in isiZulu as well as in English to improve throughput and increase the number of graduates. The aim of this study was to determine if this policy is feasible within the discipline of physics. Critical engagement with students and a literature search allowed the determination of the potential gains and pitfalls of such a language introduction. The study also provides some useful insight into student contexts, schooling history and their perceptions of being taught in their vernacular. The inconsistent use of isiZulu words to translate basic physics words will require the development of a common vocabulary for teaching physics in isiZulu. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500009&lng=es&nrm=iso&tlng=es Tuberculosis (TB) continues to present an insurmountable health burden in the Western Cape Province of South Africa. TB dynamics in adults is different from that in children, with the former determining the latter. Because the dynamics of TB are largely dependent on age, planning for interventions requires reasonable and realistic projections of the incidence across ages. It is thus important to model the dynamics of TB using mathematical models as predictive tools. We considered a TB compartmental model that is age dependent and whose parameters are set as functions of age. The model was fitted to the TB incidence data from the Cape Town metropole. The effective contact rate, a function of both age and time, was changed to fit the model to the notification rates of active TB disease cases. Our simulations illustrate that age structure plays an important role in the dynamics of TB. Projections on the future of the epidemic were made for each age group. The projected results show that TB incidence is likely to increase in the lower age groups of the population. It is clearly evident that even very simple models when applied to limited data can actually give valuable insights. Our results show that the age groups who have the highest incidence rates of active TB disease have the highest contribution in the transmission of TB. Furthermore, interventions should be targeted in the age group 25-34 years. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500010&lng=es&nrm=iso&tlng=es Medical and health sciences institutions and organisations are faced with challenges in resource allocation for research and publishing. The aim of this study was to retrospectively analyse South African publication trends in medicine to provide guidance for future strategic planning in academic medicine. We used the Scimago database spanning the years 1996-2011 to analyse South African publication outputs in a number of categories in medicine, as defined in the Scopus database. The data reveal a number of significant growth areas but also reveal areas that should potentially be growing but remain static. In some areas, growth has aligned with the expectations of health and disease trends, but other areas, in which growth would have been expected, have remained static. Interesting features are also revealed when the data are compared with those of other developed and developing countries. For 1996-2011, South African medical publication output ranked 33 in the world based on the number of publications, but 28 based on the h-index. Interestingly, whilst South Africa produced less than 25% of the output of India, the h-index for South Africa is 153 compared with 145 for India. South Africa's medical publication output has steadily increased over the 14-year period but the number of citations per document has declined. This analysis provides a useful strategic overview for medical institutions and government funding organisations to guide the allocation of research budgets and resources in a discipline- or category-specific manner to influence research outputs. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500011&lng=es&nrm=iso&tlng=es Cholera toxin is the aetiological agent of cholera - a deadly waterborne disease acquired through the consumption of untreated water contaminated with CTXO bacteriophage harbouring strains of V. cholerae. Solar disinfection is a re-emerging technique that relies on the ultraviolet component of sunlight to inactivate the growth of Vibrio cholerae in water, rendering the water microbiologically safe for consumption. However, studies have shown that DNA damaging agents, such as ultraviolet light, induce the replication of the CTXO bacteriophage with subsequent expression of the cholera toxin. In this study we investigated the impact of solar irradiation on the secretion of cholera toxin by toxigenic strains of V. cholerae in water. The cholera toxin ELISA assay, qualitative and quantitative real-time PCR as well as growth on solid media were used to determine cholera toxin secretion, DNA integrity and growth of the bacteria after 7 h and 31 h of solar irradiation. Solar irradiation in water reduced the integrity of DNA, inactivated the growth of V. cholerae and, most importantly, prevented the secretion of detectable levels of cholera toxin. This finding is encouraging for resource-poor communities that may rely on solar disinfection to alleviate the burden of cholera-related fatalities. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500012&lng=es&nrm=iso&tlng=es Morphometric analyses of the patella and patellar ligament have been reported to be important in human identification, in knee implant design and in certain surgical procedures of the knee. It has also been shown that success in the functionality of a knee arthroplasty (knee replacement) is dependent on the implant being of an appropriate dimension. We undertook this study because of the lack of available data on these dimensions in South Africans. Careful dissection was carried out on both knees of 46 South African cadavers (25 females and 21 males) of European ancestry. The quadriceps femoris tendon and patellar ligament were carefully freed from the underlying structures. Eight measurements of the patella and patellar ligament were taken using a Vernier caliper. Patellae were also classified based on the dimensions of the articular facets. No significant difference was found when the measurements taken from both knees were compared except for the dimensions of patella thickness and widths. Dimensions of the patella, patellar ligament and articular facets are sexually dimorphic. In addition, measurements of the patella and patellar ligament showed significant positive correlations, with Type B patellae being the most prevalent in South Africans of European ancestry. The data from the present study will be beneficial in clinical and pathological practices and for local anthropological records. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500013&lng=es&nrm=iso&tlng=es In addition to clearing invasive alien plants, the Working for Water (WfW) Programme, as a South African government public works programme, provides short-term employment and training to empower the poor in finding alternative employment within the labour market. Several studies indicate that its beneficiaries become financially dependent on WfW projects and tend to be reluctant to leave the programme. The sociological reasons for this reluctance, however, remain largely unstudied. We therefore address this gap by reporting on a case study of four WfW projects in the Western Cape Province. Face-to-face interviews with beneficiaries suggest that a number of push and pull factors contribute to their dependency on WfW. Chief among these factors is a fear among previous farmworkers of returning to farm work. It was found that the latter can be linked to a historical power-relations legacy between landowners and farmworkers, mainly created by institutional racism still prevailing on many Western Cape farms. These findings bear important implications for the implementation of a new draft WfW policy aimed at encouraging private landowners to employ WfW beneficiaries on their land as clearers of invasive alien plants. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500014&lng=es&nrm=iso&tlng=es Increased workloads and curriculum changes have become an integral part of the teaching profession. Knowledge of the major stressors and stress symptoms of teachers is required for proper stress management. We therefore aimed to determine the major stressors and stress symptoms experienced by Grade 10-12 Life Science (previously known as Biology) educators in government schools in Tshwane North (Gauteng, South Africa), as well as to assess their time distribution and their needs with regard to academic support. Questionnaires were sent to the Grade 10-12 Life Science educators in 94 government schools in Tshwane North. Participation was voluntary and anonymous. Only teachers from 36 schools responded. A total of 53.9% of these educators indicated that they spend more than 50 hours each week on school-related activities, 17.3% of whom spend between 60 hours and 64 hours and 9.6% spend more than 74 hours. When asked if they had felt stressed during the 3 months preceding the study, 81.1% of respondents replied in the affirmative; 70.5% of whom felt that school-related factors contributed the most to their stress. Factors identified as major contributors to this stress were: learners' poor behaviour and attitude and lack of discipline, lack of time, large class sizes, and teaching a learning area in which they were not trained. Educators indicated that they prefer assistance in the form of a book containing portfolio tasks with accompanying assessment tools and suggested memoranda, as well as workshops at their schools. Stress management programmes should be needs directed. Stressors can largely be alleviated by proper consultation and planning on the side of the higher authorities, additional academic support and the availability of appropriate funding. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500015&lng=es&nrm=iso&tlng=es The advanced use of inorganic membranes, such as zeolites, in large-scale industrial processes is hindered by the inability to manufacture continuous and defect-free membranes. We therefore aimed to construct such a defect-free membrane. Various zeolites were synthesised on the inner surface of a-alumina support tubes by a hydrothermal process. Gas permeation properties were investigated at 298 K for single component systems of N2, CF4 and C3F6. Ideal selectivities lower than Knudsen selectivities were obtained as a result of defects from intercrystalline slits and crack formation during synthesis and template removal. A composite ceramic membrane consisting of a ceramic support structure, a mordenite framework inverted intermediate zeolite layer and a Teflon AF 2400 top layer was developed to improve separation. The Teflon layer sealed possible defects present in the separation layer forcing the gas molecules to follow the path through the zeolite pores. Ideal selectivities of 88 and 71 were obtained for N2/CF4 and N2/C3F6 respectively. Adsorption experiments performed on materials present in the membrane structure suggested that although adsorption of C3F6 onto Teflon AF 2400 compared to CF4 results in a considerable contribution to permeation for the composite ceramic membrane, the sealing effect of the zeolite layer by the Teflon layer is the reason for the large N2/CF4 and N2/C3F6 selectivities obtained. The Teflon layer effectively sealed intercrystalline areas in-between zeolite crystals, which resulted in high ideal selectivies for N2/CF4 and N2/C3F6. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500016&lng=es&nrm=iso&tlng=es Acid mine drainage has become a serious environmental concern in South Africa, particularly for the long-term sustainability of the country's fresh water supply. Such concerns were dramatically highlighted in January 2012 when water in the Boesmanspruit Dam, which supplies the town of Carolina with potable water, underwent rapid deterioration following a large rainstorm event. A sudden drop in pH to 3.7, accompanied by elevated levels of iron, aluminium, manganese and sulphate rendered the water toxic and unsuitable for use. The problem remained unresolved for 7 months, provoking community protests and eventually court action against the Department of Water Affairs. Although evidence pointed to coal mining as the source of contamination, it was unclear how the dam became polluted so rapidly. We investigated the events surrounding the contamination of Carolina's water supply, in an attempt to identify a possible cause and to assess whether the event has relevance for other dams in the Vaal River system. Chemical analyses of water samples revealed that the pollution originated from the Witrandspruit subcatchment where seepage from coal mines had accumulated in a wetland upstream of the dam. During an unusually heavy downpour, ponds holding polluted run-off from coal handling facilities overtopped and flushed the contents of the wetland into the Boesmanspruit Dam. While a recurrence of the event at Carolina is possible, major dams in the upper Vaal River catchment are unlikely to experience a similar catastrophic event. In the long term, pollution of these dams is likely to proceed gradually, as is currently occurring at the Middelburg and Witbank Dams. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500017&lng=es&nrm=iso&tlng=es Quantitatively assessing the scientific relevance of a research paper is challenging for two reasons. Firstly, scientific relevance may change over time, and secondly, it is unclear how to evaluate a recently published paper. The temporally averaged paper-specific impact factor is defined as the yearly average of citations to the paper until now including bonus citations equal to the journal impact factor in the publication year. This new measure subsequently allows relevance rankings and annual updates of all (i.e. both recent and older) scientific papers of a department, or even a whole scientific field, on a more objective basis. It can also be used to assess both the average and overall time-dependent scientific relevance of researchers in a specific department or scientific field. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500018&lng=es&nrm=iso&tlng=es The highly pathogenic avian influenza virus H5N1 is a potent pandemic threat because of its frequent transmission from birds to humans and the increasing possibility of human to human transmission. During the 2009 H1N1 pandemic it was clear that rapid influenza vaccine production is a problem worldwide. Additionally, developing countries like South Africa generally cannot produce their own influenza vaccines because the traditional egg-based vaccine production method currently employed is too lengthy and too difficult to establish. As part of an exercise aimed at exploring the feasibility of producing emergency response influenza vaccines, we investigated an experimental DNA vaccine to the H5N1 influenza virus. We focused on the virion haemagglutinin, because it elicits the primary neutralising immune response following infection. Accordingly, we developed an H5N1 DNA vaccine with full-length and truncated versions of the haemagglutinin gene, to match previously developed protein candidates. Vaccinated mice developed a strong antibody response to the haemagglutinin protein. In addition, the full-length H5 gene elicited high haemagglutination inhibition titres in mice, indicating that it has potential as a candidate pandemic vaccine for South Africa. http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532013000500019&lng=es&nrm=iso&tlng=es Trade in live, freshwater crayfish for ornamental markets, as well as for aquaculture, has grown rapidly and has become the major pathway for the introduction of non-indigenous crayfish species to several countries worldwide. Here we report on the first record of the Australian 'redclaw' Cherax quadracarinatus in the natural waters of a game reserve in South Africa. To compound the situation, these redclaw crayfish were infected with a non-indigenous temnocephalan flatworm parasite. Both crayfish and temnocephalan were in full breeding condition, with young. Further spreading of this crayfish to the subtropical, water-rich, northern KwaZulu-Natal Province of South Africa and southern Mozambique is predicted. Not only might the crayfish compete with indigenous aquatic invertebrates but the non-host-specific temnocephalan might transfer to local decapods, such as freshwater crabs.