Scielo RSS <![CDATA[South African Journal of Science]]> http://www.scielo.org.za/rss.php?pid=0038-235320080006&lang=en vol. 104 num. 11-12 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Establishing a basis for ecosystem management in the western Indian Ocean</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600001&lng=en&nrm=iso&tlng=en <![CDATA[<B>F.J. Hewitt</B>: <B>(1919-2007)</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600002&lng=en&nrm=iso&tlng=en <![CDATA[<b>Arthur Bleksley</b>: <b>pioneer of science awareness in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600003&lng=en&nrm=iso&tlng=en <![CDATA[<B>Aloes in the Eastern Cape of South Africa</B>: <B>the value of natural history observations in biological sciences</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600004&lng=en&nrm=iso&tlng=en <![CDATA[<B>Banning order by local journal</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600005&lng=en&nrm=iso&tlng=en <![CDATA[<B>Our ancient forebears got there first</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600006&lng=en&nrm=iso&tlng=en <![CDATA[<B>Behind the veil</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600007&lng=en&nrm=iso&tlng=en <![CDATA[<B>Recalling how it was</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600008&lng=en&nrm=iso&tlng=en <![CDATA[<B>Scholarly publishing in South Africa</B>: <B>facing reality</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600009&lng=en&nrm=iso&tlng=en <![CDATA[<B>What became of the <I>SAJS</i></B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600010&lng=en&nrm=iso&tlng=en <![CDATA[<B>From generalities to specifics in San rock art</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600011&lng=en&nrm=iso&tlng=en <![CDATA[<b>Science councils in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600012&lng=en&nrm=iso&tlng=en <![CDATA[<B>A comparison of the cost of research in South Africa's public research and higher education institutions</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600013&lng=en&nrm=iso&tlng=en Despite the importance of labour and overhead costs to both funders and performers of research in South Africa, there is little published information on the remuneration structures for researchers, technician and research support staff. Moreover, there are widely different pricing practices and perceptions within the public research and higher education institutions, which in some cases do not reflect the underlying costs to the institution or the inherent value of the research. In this article, data from the 2004/5 Research and Development Survey have been used to generate comparative information on the cost of research in various performance sectors. It is shown that this cost is lowest in the higher education institutions, and highest in the business sector, although the differences in direct labour and overheads are not as large as may have been expected. The calculated cost of research is then compared with the gazetted rates for engineers, scientists and auditors performing work on behalf of the public sector, which in all cases are higher than the research sector. This analysis emphasizes the need within the public research and higher education institutions for the development of a common pricing policy and for an annual salary survey, in order to dispel some of the myths around the relative costs of research, the relative levels of overhead ratios and the apparent disparity in remuneration levels. <![CDATA[<B>Global and local forces shaping the research agenda and the governance of research ethics</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600014&lng=en&nrm=iso&tlng=en Powerful global forces shape and skew the science research agenda, generally. We describe these and the local forces that fashion research priorities in science, technology and health in South Africa. We conclude with some comments on the governance of research ethics globally and locally. <![CDATA[<B>Latest information on Sterkfontein's <I>Australopithecus</I> skeleton and a new look at <I>Australopithecus</i></B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600015&lng=en&nrm=iso&tlng=en After a decade of careful excavation, it is now possible to explain how the skeleton came to be in that isolated position in the cavern. Furthermore, it is apparent that the fossil does not belong to either Australopithecus africanus or to A. afarensis, but to an individual belonging to, or closely affiliated to, the second Australopithecus species that is represented in Sterkfontein Member 4 and Makapansgat. <![CDATA[<B>What can we learn about the meaning of race from the classification of population groups during apartheid?</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600016&lng=en&nrm=iso&tlng=en This paper examines what might be learnt about the meaning of race from the formalization of racial classification and reclassification under apartheid, generated by the 1950 Population Registration Act. It draws on 69 (re)classification appeals heard by the South African Supreme Court between 1950 and 1991, and in-depth interviews with a civil servant, expert witness and scientist involved in the (re)classification process. The Supreme Court data indicate that the three classificatory criteria set out in the act (appearance, descent, and acceptance) were ambiguous and subject to substantial debate and reinterpretation by the courts, which principally relied on acceptance. This is supported by the interviewees, who lamented the 'unscientific' classifications they were obliged to perform, yet accepted these as the inevitable consequence of the role social practices play in determining and accepting the classification applied. These findings suggest that there was not a single concrete definition of race during apartheid. Instead, race was whatever people understood or wanted it to be, and racial classification could be attained through 'performing' an identity with sufficient proficiency to 'get away with it'. This provides a crucial insight into the meaning of race elsewhere-as simply a flexible, yet pragmatic and 'acceptable' social classification of group identity. <![CDATA[<B>Surface polarity determination of wood fibres after different pre- treatments and bisulphite pulping</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600017&lng=en&nrm=iso&tlng=en The surgace polarity of pulp fibres originating from four different wood species commonly used for pulping in South Africa has been determined after various pre-treatments, and after magnesium bisulphite pulping. The presence as well as the distribution of polar groups on the fibre surface strongly affects inter-fibre bonding in paper. Bonding consists mostly of hydrogen bonds between free hydroxyl groups on the fibre surface. Surface polarity was examined by atomic force microscopy in pulsed-force mode. This technique allows the imaging of the polarity of a surface with a nanometre-scale molecular resolution. It is thus sensitive to individual functional groups, mostly hydrophilic hydroxyl groups. Polarity differences between the various wood species have been observed. We compare these observations with the varying pulp quality that arises from the pulp composition. Improvement in pulp quality may be possible if fibre surface properties are used as guidance criteria for the choice of a specific pre-treatment method. <![CDATA[<B>Development and refinement of a portable electronic device for haematocrit determination</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600018&lng=en&nrm=iso&tlng=en A small portable eletronic device, named a blood electrometer (BEM), was developed to measure packed cell volume, which can be related to haematocrit (Hct). The electronic circuitry is simple and constructed from standard components. Being battery powered, the device is suitable for bedside or field use ('point-of-care-testing') without specialized training. The effects of temperature, anticoagulants, lipid content, electrode type and different BEM electronic circuits on measurement accuracy were evaluated. A method for calibrating the instrument with a sodium chloride calibrator was also devised and evaluated for measurement accuracy. The response of the BEM to Hct is non-linear; a binomial regression function was used to fit the non-linear response to provide accurate Hct values from BEM readings over a wide range of measurements. The BEM response curve is sensitive to the anticoagulant type used, but specific binomial functions reduce error to between -3.1% and +3.3% Hct units. Lipids do not significantly affect BEM readings, even at high concentrations of 9.8 mmol/l. We conclude that the BEM can be relied on for acceptably accurate Hct measurements under a variety of conditions, and can be used for the indirect determination of packed cell volume. <![CDATA[<B>Ocean currents south of Africa from drifters</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600019&lng=en&nrm=iso&tlng=en The ocean currents and their variability south of Africa are known to cover a wide spectrum, spatially and possibly temporally. Hydrographic observations in this vast ocean region are logistically demanding and expensive. In recent years the prevalence of drifting buoys has allowed one to infer certain current characteristics for the region that otherwise would be difficult. Observations from satellite-tracked drifters drogued at a depth of 15 m, collected between 1988 and 2005, were used to infer the mean surface circulation and kinetic energy distributions of the surface flow in the African sector of the Southern Ocean between 30 and 60°S. Regions of intensified flow and of higher levels of eddy kinetic energy were identified and agree fairly well with those established from remote sensing products. These results confirm the value of these observations and indicate the increasing usefulness of this data set as the number of drifter tracks increases. <![CDATA[<B>Probing the Universe with cosmic rays using high performance computing</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600020&lng=en&nrm=iso&tlng=en I report on the research activities of the South African Centre for High Performance Computing carried out at the Unit for Space Physics at North-West University, Potchefstroom, during 2007/8. Background is given on the aims of the centre and the first three flagship projects that were selected in 2006 for computational-intensive tasks. The project in Computational Space Physics and Astrophysics, called 'Cosmic rays and us: From birth to death', is described in detail, and a summary given of research highlights so far. <![CDATA[<B>Struvite infection calculi in dogs</B>: <B>problems with urinary calculus identification, and the value of the results</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600021&lng=en&nrm=iso&tlng=en Identifying the crystalline components of a urinary calculus is a valuable aid to correct diagnosis, and subsequent treatment of the underlying cause of the problem. Calculus formation is often an end product brought about by urine with a high concentration of insoluble material causing bladder irritation. This promotes bacterial infection by Proteus, which not only raises the pH in the bladder and generates ammonia, but also provides sites for mineral nucleation and crystal growth. Treating the infection and removing the stone will not necessarily cure the disorder. Correct identification of a calculus as struvite and even its potassium analogue can be critical in choice of curative protocols, but this is not always straightforward. Our experience with 'problem calculi' is described. <![CDATA[<B>Perspectives on botanical research publications in South Africa</B>: <B>an assessment of five local journals from 1988 to 2002, a period of transition and transformation</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600022&lng=en&nrm=iso&tlng=en South Africa has every right to take pride in its rich and unique botanical diversity. As part of investigating the discipline of botany in the country, we have assessed the contents of five botany-related South African journals in the period 1988-2002, analysing the sub-disciplines, affiliations of the contributors, and the age, gender and race of the first authors. The results show various trends, such as a decline in the number of articles during the 1990s and then an increase in 2001 and 2002. A specific niche for each of the five journals has been identified. These journals have adopted strategies and introduced improvements to survive change in the evolving scientific environment. Most articles are from authors in the age group 31-40; men accounted for 68% of botanical papers and women 32%. Whites authored 94%, and other racial groups 6%. The botanical sciences are among the leaders in South African research publications in terms of output and citations. <![CDATA[<B>Description of the postcranial anatomy of <I>Aulacephalodon baini</I> and its possible relationship with '<I>Aulacephalodon peavoti</I>'</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600023&lng=en&nrm=iso&tlng=en A recent analysis of the postcranial anatomy of Triassic dicynodonts renewed interest in the anatomy of Aulacephalodon. This study focused initially on Aulacephalodon baini as it represents medium to large Permian dicynodonts but also took into account 'Aulacephalodon peavoti'. The postcranial skeletons of A. baini and 'A. peavoti' show several significant differences. The scapula blade of A. baini is more curved than and not as upright as in 'A. peavoti'. A. baini has a rectangular delto-pectoral crest and has a better developed olecranon. In the pelvic girdle the anterior process is higher than the posterior process of the ilium in A. baini and the acetabulum is directed more ventrally. The femoral head is separated from the greater trochanter in A. baini. A comparison also shows that both A. baini and 'A. peavoti' are different from Rhachiocephalus in that the latter has a widely expanded scapula blade and the proximal end of the humerus is wider than the distal. The glenoid is elliptical with a convex surface. Although it could not be conclusively decided what the taxonomic position of 'A. peavoti' is, this study provides information about the postcranial skeleton which could aid its detailed analysis. This study will also assist in clarifying the relationships as well as providing insight into the palaeobiology of these extinct tetrapods. <![CDATA[<B>Co-authorship networks in South African chemistry and mathematics</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600024&lng=en&nrm=iso&tlng=en Co-authorship networks are graphs in which the nodes of the graph represent authors and two authors are connected by an edge if they have written one or more papers together. When applied to the authorship of scholarly papers, analysing the structure of a co-authorship network can provide useful insights into the way in which research is carried out in a particular field. We examine two co-authorship networks in our article, constructed from papers written on the subjects of chemistry and mathematics during the period 1990 to 2005, in which at least one of the authors was South African. Local results are compared with other studies conducted in much larger discipline-wide networks. We find that many of the same patterns exist locally, with the main difference being a far more fragmented South African mathematics network. We discuss some tentative implications of these results. <![CDATA[<B>Radiometric dating of hillslope calcrete in the Negev Desert, Israel</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600025&lng=en&nrm=iso&tlng=en The radiometric dating of calcrete is often problematical because impurities and open system conditions affect the apparent ages obtained. By applying both radiocarbon and uranium-series dating to calcrete in colluvium, it is shown that such conditions can be identified. In correlation with the stratigraphy, it is found that partial recrystallization severely decreases the radiocarbon ages of the upslope and shallower samples further down, whereas incorporation of limestone fragments from bedrock significantly increases the apparent ages of some of the uranium-series samples. It is concluded that the hillslope calcrete at the study site near Sede Beker in the Negev Desert, Israel, mainly developed shortly after 40 kyr ago, at a time when the Jordan Valley was being inundated to form the fossil Lake Lisan. Since their formation would have required higher rainfall than today, the results provide further evidence that the whole region was experiencing an increase in precipitation. <![CDATA[<B>Palladium-polyaniline type composite polymers</B>: <B>using catalysis as a monitor of palladium location</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600026&lng=en&nrm=iso&tlng=en The location of nanosized (2-4 nm) palladium particles in two palladium-polyaniline-based composites, synthesized by the redox coupling route using monomer and palladium(II) acetate, have been revealed using ethene hydrogenation as a heterogeneously catalysed reaction, together with differential scanning calorimetry. The two palladium composites were synthesized using m-aminobenzoic acid (ABA) or o-phenylenediamine (PDA), leading to Pd-PABA or Pd-PPDA, respectively. The temperature sensitivity of catalytic activity related to the polymer melting temperature, as revealed by DSC, assists in understanding the location of the palladium particles. The structures of the metal-polymer composite at the micrometre and nanometre levels are revealed using scanning and transmission electron microscopy, respectively. <![CDATA[<B>Mitochondrial DNA diversity and population structure of a forest-dependent rodent, <I>Praomys taitae</I> (Rodentia: Muridae) Heller 1911, in the fragmented forest patches of Taita Hills, Kenya</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600027&lng=en&nrm=iso&tlng=en The population genetic structure of the forest-dependent rodent, Praomys taitae, sampled from nine indigenous forest fragments distributed over three ranges of the Taita Hills in Kenya, was determined using mitochondrial DNA (mtDNA) control region sequence variation. Thirty-three unique haplotypes were observed in a total sample of 132 individuals, whereas the number of different haplotypes per population ranged from two to 10. An overall low nucleotide diversity of 0.9% was observed in the total sample but varied widely between populations (0.2-1.3%). Significant genetic differentiation was observed in 30 of the 36 possible pair-wise comparisons between populations, while a hierarchical AMOVA revealed significant genetic subdivision between groups of populations on the three hill ranges of Dabida, Mbololo and Kyulu (F CT = 0.404, P < 0.01), among populations on each of the hill ranges (F SC = 0.112, P < 0.01) and among populations in the total sample (F ST = 0.471, P < 0.001). Demographic history analyses based on pair-wise nucleotide sequence mismatch distributions revealed that all the populations were in mutation-drift disequilibrium except the populations of the Kyulu and Ronge forest fragments. <![CDATA[<B>Vegetation associated with the occurrence of the Brenton blue butterfly</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600028&lng=en&nrm=iso&tlng=en The Brenton blue butterfly, Orachrysops niobe (Trimen), is critically endangered and known only from one site near Knysna in the Western Cape province of South Africa, now proclaimed as the Brenton Blue Butterfly Reserve (BBBR). We have explored associations between vegetation types and the presence of O. niobe's only host plant, Indigofera erecta (Thunb.), using Braun-Blanquet vegetation classification and ordination techniques as part of a broader research project at the BBBR. Positive correlations are demonstrated between the occurrence of I. erecta and certain thicket vegetation types dominated by Pterocelastrus tricuspidatus (candlewood trees). Ordinations using soil analysis and slope data have not detected significant environmental gradients influencing vegetation types. The high degree of vegetation heterogeneity at the BBBR appears to be driven in part by various disturbance histories. Historical ecological events at the site such as fire and megaherbivore impacts, and their role in sustaining the ideal habitat for I. erecta and O. niobe, are discussed. Management techniques for the BBBR such as controlled fires or the cutting of paths through the vegetation are evaluated and an optimum future management strategy is recommended. This is the most comprehensive vegetation study ever carried out at the habitat of an endangered butterfly in South Africa, and breaks new ground by using vegetation analysis to develop a well-informed management plan for conservation of this species. It has significance for the management of small sites where many such endangered butterflies occur. <![CDATA[<B>The first fossil of the Congo peafowl (Galliformes: <I>Afropavo</I>)</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600029&lng=en&nrm=iso&tlng=en A fossil from the Middle Stone Age internal deposits of Plovers Lake Cave in the Sterkfontein Valley, Gauteng province, South Africa, is the first fossil specimen that can be allocated to the Congo peafowl (Afropavo congensis), a species that is currently endemic to the Democratic Republic of Congo in central Africa. The fossil greatly extends the known geographic range of this rainforest taxon and suggests the presence of forested or even rainforest habitats near Plovers Lake Cave during the Middle Stone Age when the fossil was deposited. The presence of this central African taxon in South Africa implies that either its geographic range expanded during a period of climate change during the late Pleistocene or that its currently restricted distribution is a relict of a more extensive past distribution across a larger part of Africa. <![CDATA[<B>Enhanced stabilization of collagen-based dermal regeneration scaffolds through the combination of physical and chemical crosslinking</B>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532008000600030&lng=en&nrm=iso&tlng=en The use of collagen in the biomedical device industry has led to major advances in soft tissue repair. This is attributed largely to the favourable biological and physiochemical properties of collagen. Regenerative medicine and tissue engineering favoured the use of this biomaterial and various commercial products have become available in the past few decades. This study aims to develop a collagen and chondroitin-6-sulphate dermal regeneration scaffold with enhanced resistance against enzymatic degradation. Frozen slurries (0.5% collagen) were dried under vacuum, coated with silicone, crosslinked and then thoroughly rinsed. The scaffolds were subjected to a range of quantitative and qualitative tests that included: scanning electron microscopy analysis, collagenase enzymatic degradation, and cytotoxicity assessment. Scaffold resistance to enzymatic degradation was manipulated after dehydrothermal treatment by employing combinations of crosslinking agents, such as glutaraldehyde and/or carbodiimide, with or without the presence of L-lysine. Results indicate that highly porous (mean pore diameter of 87.3 µm), bioactive, non-cytotoxic tissue engineering matrices were obtained. Enhanced stability of these scaffolds was achieved through extensive crosslinking and suggests the potential to prevent in vivo wound contraction sufficiently.