Scielo RSS <![CDATA[South African Journal of Science]]> vol. 106 num. 7-8 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>The higher education summit re-opens the debate on differentiation</b>]]> <![CDATA[<b>'African dinosaurs'</b>: <b>permanent new exhibition at the South African Museum</b>]]> <![CDATA[<b>The world as it is made to seem</b>]]> <![CDATA[<b>Robert Griffiths Hodgins (1920-2010)</b>]]> <![CDATA[<b>The great changing room of colour and class</b>]]> <![CDATA[<b>Comparisons between <i>Australopithecus sediba</i> (MH1) and other hominin taxa, in the context of probabilities of conspecificity</b>]]> <![CDATA[<b>A critical review of studies of South African youth resilience, 1990-2008</b>]]> Given the growing emphasis in research and service provision on strengths rather than deficits, the focus on youth support in the South African Children's Act of 2005 and the lack of educational, therapeutic and other resources for most South Africans, insight into, and transdisciplinary commitment to, resilience is crucial. Resilience, or the phenomenon of 'bouncing back' from adversity, is common to societies that grapple with threatened well-being. Increasingly, international resilience studies have suggested that the capacity to rebound is nurtured by multiple resources that protect against risk and that these resources are rooted in culture. In this paper, we critically reviewed 23 articles that focus on South African youth resilience, published in academic journals between 1990 and 2008. By broadly comparing South African findings to those of international studies, we argued for continued research into the phenomenon of resilience and for a keener focus on the cultural and contextual roots of resilience that are endemic to South Africa. Although international resilience research has begun to match the antecedents of resilience to specific contexts and/or cultures, South African research hardly does so. Only when this gap in youth resilience research is addressed, will psychologists, service providers, teachers and communities be suitably equipped to enable South African youth towards sustained resilience. <![CDATA[<b>The internationalisation of South African medical research, 1975-2005</b>]]> South Africa's record in the production of scientific knowledge in medicine is remarkable, but attempts have yet to be made to examine its distinctive characteristics. This is critical to the understanding of its nature, trends and the directions which it is taking today. Using the publication records extracted from the Science Citation Index (SCI) of the ISI Web of Science for a 3-decade period from 1975 to 2005, with 5-year windows, Ihave examined the salient characteristics of medical research in South Africa in terms of, (1) the number of publications, (2) type of publications (sole/co-authored), (3) collaboration (domestic/international), (4) affiliation sector of authors and collaborators, (5) regional origin of collaborators, (6) publication outlets and (7) citations, in comparison with 'all subjects' covered in the database concerned. This analysis shows that the contribution of medical publications to the total output of South African scholars is shrinking (25% in 1980 to 8% in 2000). Papers produced in collaboration are growing in number (increased by 17% during 1975-2005). While domestic collaboration declined by 24%, international collaboration grew from 4% of total papers in 1975 to 48% in 2005. South African medical researchers now publish more in foreign-originated journals (from 20% in 1975 to 75% in 2005) than in local journals and work mostly in universities, hospitals and research institutes; they collaborate with overseas partners from as many as 56 countries. Significantly, collaboration with Western European partners has increased 45-fold from 1975-2005. This study showed that a marked degree of internationalisation (measured in terms of international collaboration, publications in foreign journals and the number of citations) of South African medical research is taking place and that this trend is likely to continue in the future. <![CDATA[<b>Land-cover change in the Kruger to Canyons Biosphere Reserve (1993-2006)</b>: <b>a first step towards creating a conservation plan for the subregion</b>]]> This paper is a first step towards a conservation plan for the Kruger to Canyons Biosphere Reserve (K2C) on the South African Central Lowveld, quantifying the historical land-cover trends (1993-2006). During the analysis period, 36% of the biosphere reserve (BR) underwent land-cover change. Settlement areas increased by 39.7%, mainly in rural areas, becoming denser, particularly along roadways. Human-Impacted Vegetation increased by 6.8% and Intact Vegetation declined by 7.3%, predominantly around settlement areas, which is testament to the interdependency between rural communities and the local environment. However, settlement expansion exceeded the rate of rangeland growth; in the long term, this may raise questions for sustainable resource extraction. Similarly, the block losses of intact vegetation are of concern; issues of fragmentation arise, with knock-on effects for ecosystem functioning. In the economic sector, agriculture increased by 51.9%, while forestry and mining declined by 7.1% and 6.3%, respectively. The future of these three sectors may also have significant repercussions for land-cover change in the BR. The identification of historical drivers, along with the chance that existing trends may continue, will have important implications for biodiversity protection in this landscape. Applied within a conservation-planning framework, these land-cover data, together with economic and biodiversity data, will help reconcile the spatial requirements of socio-economic development with those of conservation. <![CDATA[<b>A review of performance standards to monitor, evaluate and assess the impact of technology transfer offices</b>]]> The conversion of scientific discoveries to new products and processes and their launch onto the market can be a lengthy process. Similarly, it takes many years before the impact of scientific research on society and the economy is realised and a further length of time before its performance can be measured. Higher education and research institutions, and their governments, often make significant investments into intellectual property management and technology transfer activities through legislative and policy development, human resource development, financial allocation and infrastructure improvement. Since returns on such investments are not immediately apparent, it is important to establish a means by which the impact of their efforts can be determined. In this paper, I examined the measures and indicators that could be developed by institutions and their stakeholders in order to monitor, evaluate and determine the impact of research output and outcomes on the market. <![CDATA[<b>Dichloro(bis[diphenylthiourea])cadmium complex as a precursor for HDA-capped CdS nanoparticles and their solubility in water</b>]]> A single-source precursor route has been explored by using the diphenylthiourea cadmium complex as the source of cadmium sulphide (CdS) nanoparticles. The reaction was carried out using hexadecylamine (HDA) as the solvent and stabilising agent for the particles. The phenylthiourea complex was synthesised and characterised by means of a combination of spectroscopic techniques, microanalysis and X-ray crystal structural analysis. The diphenylthiourea complex was thermolysed in HDA at 120 ºC for 1 h to produce CdS nanoparticles. The CdS nanoparticles prepared were made water-soluble via a ligand exchange reaction involving the use of pyridine to displace HDA. The pyridine was, in turn, replaced by glucose and glucuronic acid. The absorption and emission spectra showed the typical features of quantum confinement for the nanoparticles for both HDA-capped and glucose- or glucuronic acid-capped CdS nanoparticles. The change in the capping groups, from HDA to glucose and glucuronic acid, resulted in absorption and emission features that were almost similar, with only slight red-shifting and tailing. <![CDATA[<b>Optimisation of automated ribosomal intergenic spacer analysis for the estimation of microbial diversity in fynbos soil</b>]]> Automated ribosomal intergenic spacer analysis (ARISA) has become a commonly used molecular technique for the study of microbial populations in environmental samples. The reproducibility and accuracy of ARISA, with and without the polymerase chain reaction (PCR) are important aspects that influence the results and effectiveness of these techniques. We used the primer set ITS4/ITS5 for ARISA to assess the fungal community composition of two sites situated in the Sand Fynbos. The primer set proved to deliver reproducible ARISA profiles of the fungal community composition with little variation observed between ARISA-PCRs. Variation that occurred in a sample due to repeated DNA extraction is expected for ecological studies. This reproducibility made ARISA a useful tool for the assessment and comparison of diversity in ecological samples. In this paper, we also offered particular suggestions concerning the binning strategy for the analysis of ARISA profiles. <![CDATA[<b>The use of a genetic algorithm in optical thin film design and optimisation</b>]]> We used a genetic algorithm in the design and optimisation of optical thin films and present the effects of the choice of variables, refractive index and optical thickness, in both applications of this algorithm, in this paper. The Fourier transform optical thin film design method was used to create a starting population, which was later optimised by the genetic algorithm. In the genetic algorithm design application, the effect of the choice of variable was not distinct, as it depended on the type of design specification. In the genetic algorithm optimisation application, the choice of refractive index as a variable showed a better performance than that of optical thickness. The results of this study indicate that a genetic algorithm is more effective in the design application than in the optimisation application of optical thin film synthesis. <![CDATA[<b>Mesoporous ethanesilica materials with bimodal and trimodal pore-size distributions synthesised in the presence of cobalt ions</b>]]> Mesoporous organosilica materials containing ethane groups in their framework were formed with two and three pore sizes (i.e. bimodal and trimodal pores) when synthesised by the sol-gel method in the presence of cobalt ions. The compounds 1,2-bistrimethoxysilylethane and tetraethylorthosilicate were used as silicon sources and the reactions were done in the presence of a surfactant, which served as a template. Diffuse reflectance infrared Fourier transform spectroscopy revealed that organic functional groups were incorporated into the ethanesilica. Powder X-ray diffraction and nitrogen adsorption data indicated that the mesophase and textural properties (surface area, pore volume, pore diameter) of the materials were dependent on the ageing temperature, the amount/ratio of silica precursors and cobalt ion incorporation. Secondary mesopores were drastically reduced by changing the ratio of silicon precursors. <![CDATA[<b>The sex profile of skeletal remains from a cemetery of chinese indentured labourers in South Africa</b>]]> For a short period of time in the early 20th century, indentured labourers from China were imported to work on the South African gold mines. The Raymond A. Dart Collection of Human Skeletons contains 36 skeletons sourced from a Chinese cemetery of this time period on the site of the old Witwatersrand Deep Gold Mine. An earlier morphometric study on this collection recorded a high number of female individuals. However, the general historical records from the early gold mining era conflict with the results of this study, stating that very few Chinese females were among those to arrive in South Africa. In this study, the sex profile of this collection was analysed using molecular sex identification through the amelogenin gene. Results were obtained for 13 (41.93%) specimens, all of which were determined to be male - data that correspond well with the historical records. <![CDATA[<b>The effect of certain <i>N</i>-tritylated phenylalanine conjugates of amino-adenosine-3',5'-cyclic monophosphate on moloney murine leukaemia virus reverse transcriptase activity</b>]]> Moloney murine leukaemia virus (M-MuLV) is a member of the retrovirus family. Its cloned reverse transcriptase (RT), similarly to HIV type 1 reverse transcriptase (HIV-1 RT), exhibits DNA-polymerase and ribonuclease H (RNase H) activities capable of converting the single-stranded retroviral RNA genome into double-stranded DNA. The latter is then integrated into the host chromosome during viral infection. M-MuLV RT is, therefore, an attractive enzyme to help understand mutations in HIV-1 RT and its use in inhibition studies can help facilitate new drug designs. In this study, conjugates consisting of N-trityl derivatives of p-fluoro, p-nitro and p-iodo-DL-phenylalanine were coupled to 8-(6-aminohexyl) amino-adenosine-3',5'-cyclic monophosphate and examined for their effect on DNA synthesis by M-MuLV RT. Synthesis was studied in a system containing poly (rA).oligo d(pT)15 as a template-primer with [³H] dTTP. The iodo-derivative, N-trityl-p-iodo-DL-phenylalanine-8-(6-aminohexyl) amino-adenosine-3',5'-cyclic monophosphate was found to be a very active inhibitor of the RT enzyme (IC50 = 1 µM), while the p-nitro (IC50 = 45 µM) and p-fluoro (IC50 = 65 µM) were weak inhibitors. Further work will be aimed at determining the mode of binding of the N-tritylated conjugates and also of various substituted amino acids and short peptides to M-MuLV RT to elucidate the mechanisms of inhibition.