Scielo RSS <![CDATA[South African Journal of Science]]> http://www.scielo.org.za/rss.php?pid=0038-235320070005&lang=en vol. 103 num. 9-10 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Key success factors for business incubation in South Africa</b>: <b>the Godisa case study</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500001&lng=en&nrm=iso&tlng=en <![CDATA[<b>The efficiency of stone and bone tools for opening termite mounds</b>: <b>implications for hominid tool use at Swartkrans</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500002&lng=en&nrm=iso&tlng=en STONE AND BONE TOOL ARTEFACTS HAVE been recovered from Swartkrans cave deposits in the Cradle of Humankind World Heritage Site, dated to the early and middle Pleistocene. It has been suggested that bone tools were used for digging up tubers of edible plants, excavating termite mounds, or as multi-purpose tools. Here we present results of experiments on the efficiency of both bone and stone tools for the excavation of modern termite mounds. Efficiency of penetrating a termite mound crust is defined by the total excavated mass of the mound, when controlling for the number of strokes used. We demonstrate that stones of considerable mass are most effective in opening up termite mounds, whereas bone tools are relatively more efficient than stone tools when controlling for mass. The light weight, efficiency, and the nature of polish and wear on some Swartkrans artefacts makes it probable that selected bone tools were being carried by hominids and used for more than one purpose. <![CDATA[<b>Anti-viral effects of aqueous extracts of <i>Aloe ferox</i> and <i>Withania somnifera</i> on herpes simplex virus type 1 in cell culture</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500003&lng=en&nrm=iso&tlng=en ALOE FEROX AND WITHANIA SOMNIFERA are among southern African plants commonly used for the treatment of sexually transmitted infections (STIs). Aqueous extracts from both species, together with aloin, isolated from A. ferox, were evaluated for antiviral activity against herpes simplex virus type 1 (HSV-1) in vitro. The aqueous extracts showed detectable activity at a concentration of 1000 µg/ml against the virus in monolayers of the Vero African green monkey cell cultures, whereas aloin showed significant activity at 62 µg/ml. HSV-1 is usually associated with mucocutaneous infections of the oropharynx but can also cause genital herpes. Herpes simplex virus type 2 (HSV-2) is the classical genital herpes pathogen, but with current sexual habits, can give rise to both oral and genito-anal infections. Our results indicate that the use of these two plant species for the treatment of STIs could have a scientific rationale. <![CDATA[<b>Deterioration of San rock art</b>: <b>new findings, new challenges</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500004&lng=en&nrm=iso&tlng=en The heritage of San rock art in southern Africa is globally acknowledged, and was one of the primary reasons for the successful nomination of the uKhahlamba/ Drakensberg Park in South Africa as a World Heritage Site.¹ Deterioration of rock paintings in the reserve could adversely affect the international status of the region, particularly as little has been achieved with regard to preserving the art for future generations. A study is currently under way in the Injisuthi and Giant's Castle areas of the park, to investigate the deterioration of San art; this article serves to introduce the project and to highlight some initial findings. Previous research on the weathering of San paintings has focused largely on either monitoring rock shelters² or investigating rock surfaces that are adjacent to the paintings. None of the methods applied in earlier investigations has considered the interface between rock and pigments, mainly because of the potential damage that may result from the use of tactile monitoring equipment. Recent advances in weathering research, using improved techniques to measure conditions at the rock surface where the San art is painted,³ provide new insights into surficial processes and suggest new lines of investigation. <![CDATA[<b>Examination of <i>Blepharis aspera </i>as a possible Cu-Ni indicator plant</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500005&lng=en&nrm=iso&tlng=en BLEPHARIS ASPERA WAS COLLECTED FROM A copper-nickel mineralized area in Botswana and examined as a possible Cu-Ni indicator plant for biogeochemical prospecting. Different plant parts and the host soils were analysed using ultrasonic slurry sampling electrothermal atomic absorption spectrometry. All plant parts accumulated Cu and Ni in above-normal amounts, although not in hyperaccumulator concentrations. The leaf to soil concentration ratio varied little with metal concentration in the soil. We propose Blepharis aspera as a Cu indicator plant. The accumulation behaviour of Blepharis aspera is compared with another previously studied metallophyte, Helichrysum candolleanum, that is growing in the same area. <![CDATA[<b>Microbiological analysis of banknotes circulating in the Venda region of Limpopo province, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500006&lng=en&nrm=iso&tlng=en WE EXAMINED USED AND NEW BANK-notes in various denominations, circulating in the Limpopo province of South Africa, for the presence of microorganisms using the rinse method. Used banknotes were collected from open-air markets, banks, filling-stations, supermarkets, residential homes and hostels. Bacteria and/or fungi were isolated from 96% of the used banknotes, and none from the new (control) notes. Twelve bacterial and one fungal species were isolated, with Staphylococcus epidermidis (13%), Candida albicans (13%), Klebsiella species (11%) and Staphylococcus aureus (11%) being the most prevalent. The low-denomination notes (R10 and R20) were the most contaminated. Infected currency is identified as a potential public health hazard, as pathogens can be spread by circulating banknotes. Immunocompromised persons stand the risk of acquiring opportunistic infections, such as C. albicans, through handling of contaminated currency. <![CDATA[<b>Ecosystems services in South Africa</b>: <b>a research theme that can engage environmental, economic and social scientists in the development of sustainability science?</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500007&lng=en&nrm=iso&tlng=en WE EXAMINED USED AND NEW BANK-notes in various denominations, circulating in the Limpopo province of South Africa, for the presence of microorganisms using the rinse method. Used banknotes were collected from open-air markets, banks, filling-stations, supermarkets, residential homes and hostels. Bacteria and/or fungi were isolated from 96% of the used banknotes, and none from the new (control) notes. Twelve bacterial and one fungal species were isolated, with Staphylococcus epidermidis (13%), Candida albicans (13%), Klebsiella species (11%) and Staphylococcus aureus (11%) being the most prevalent. The low-denomination notes (R10 and R20) were the most contaminated. Infected currency is identified as a potential public health hazard, as pathogens can be spread by circulating banknotes. Immunocompromised persons stand the risk of acquiring opportunistic infections, such as C. albicans, through handling of contaminated currency. <![CDATA[<b>Louis Pasteur, fermentation, and a rival</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500008&lng=en&nrm=iso&tlng=en WE EXAMINED USED AND NEW BANK-notes in various denominations, circulating in the Limpopo province of South Africa, for the presence of microorganisms using the rinse method. Used banknotes were collected from open-air markets, banks, filling-stations, supermarkets, residential homes and hostels. Bacteria and/or fungi were isolated from 96% of the used banknotes, and none from the new (control) notes. Twelve bacterial and one fungal species were isolated, with Staphylococcus epidermidis (13%), Candida albicans (13%), Klebsiella species (11%) and Staphylococcus aureus (11%) being the most prevalent. The low-denomination notes (R10 and R20) were the most contaminated. Infected currency is identified as a potential public health hazard, as pathogens can be spread by circulating banknotes. Immunocompromised persons stand the risk of acquiring opportunistic infections, such as C. albicans, through handling of contaminated currency. <![CDATA[<b>A framework for the informed normalization of printed microarrays</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500009&lng=en&nrm=iso&tlng=en Microarray technology has become an essential part of contemporary molecular biological research. An aspect central to any microarray experiment is that of normalization, a form of data processing directed at removing technical noise while preserving biological meaning, thereby allowing for more accurate interpretations of data. The statistics underlying many normalization methods can appear overwhelming to microarray newcomers, a situation which is further compounded by a lack of accessible, non-statistical descriptions of common approaches to normalization. Normalization strategies significantly affect the analytical outcome of a microarray experiment, and consequently it is important that the statistical assumptions underlying normalization algorithms are understood and met before researchers embark upon the processing of raw microarray data. Many of these assumptions pertain only to whole-genome arrays, and are not valid for custom or directed microarrays. A thorough diagnostic evaluation of the nature and extent to which technical noise affects individual arrays is paramount to the success of any chosen normalization strategy. Here we suggest an approach to normalization based on extensive stepwise exploration and diagnostic assessment of data prior to, and after, normalization. Common data visualization and diagnostic approaches are highlighted, followed by descriptions of popular normalization methods, and the underlying assumptions they are based on, within the context of removing general technical artefacts associated with microarray data. <![CDATA[<b>The collapse of Johannesburg's Klip River wetland</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500010&lng=en&nrm=iso&tlng=en The Klip River wetland south of Johannesburg has long been economically important to the region, initially as a source of water, and latterly as a purifier of polluted water arising from the western section of the Witwatersrand urban-industrial-mining complex. A geomorphological investigation into the current state of the wetland has revealed that the upper reaches, which receive polluted water from old gold mines, are in reasonable condition, apart from a few sections that have been severely degraded by peat mining. The lower reaches, however, are in an advanced stage of collapse. A network of irrigation canals, dug to support intensive agriculture during the early part of the last century, provided nuclei for the development of major channels as discharge of treated sewage water increased in the latter portion of the century. The channels have become interconnected, and an almost continuous, single channel has formed downstream of the sewage works. The problem is likely to have been exacerbated by a falling water table in the area due to excessive groundwater extraction. The wetland's ability to remove phosphates and nitrates from the water has been seriously compromised, and eutrophication problems can consequently be expected to arise in the Vaal River above the Barrage. In addition, it is anticipated that the reed beds flanking the single channel will degrade over the coming years, releasing sequestered heavy metals, organic load and phosphates into the Vaal River system. <![CDATA[<b>Intensity, energy and erosivity attributes of rainstorms in the KwaZulu-Natal Drakensberg, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500011&lng=en&nrm=iso&tlng=en Rainfall intensity, kinetic energy and erosivity were analysed for 106 erosive storm events at five locations in the KwaZulu-Natal Drakensberg, from late 2001 to early in 2006. The stations cover an altitudinal range of 1060 m to 3165 m a.s.l. and provide the first detailed rainstorm data for the Drakensberg area. Erosive storm events, defined as total rainfall exceeding 12.5 mm and a maximum 5-minute intensity greater than 25 mm h-1, are found to vary in duration and depth (total rainfall) with the distribution biased towards shorter, shallower storms. Erosive rainstorms are almost exclusively a summer phenomenon and the attributes of these storms (rainfall intensity, kinetic energy and erosivity) are positively correlated with rainfall depth, but not with storm duration. Inter-station similarities exist with respect to rainfall depths and mean kinetic energy from individual storm events. Altitudinal trends are, however, evident for storm maximum intensity, depths of erosive storms and cumulative kinetic energy. Together with frequency of erosive events and extent of collective erosive effects, all these rainfall attributes decrease with station altitude. Dissimilarities in cumulative kinetic energy and cumulative erosivity can be explained by the lack of erosive events during early and late summer on the escarpment and by significant erosive rains during this period at lower altitudes in the foothills. <![CDATA[<b>The extractive metallurgy of copper at Iron Age Madikwe</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500012&lng=en&nrm=iso&tlng=en SEM/EDX analysis of ores and slag showed that, with the possible exception of the Wonderboom site, copper was probably smelted from Dwarsberg ore at Madikwe, North West province, in the mid-seventeenth century, either with high iron content or with lower iron content plus an added iron oxide flux. Our analytical technique was adequate as a survey technique here, but low instrument sensitivity limited our ability to be more specific about ore sources. <![CDATA[<b>Re-interpreting the evidence for bipedality in <i>Homo floresiensis</i></b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500013&lng=en&nrm=iso&tlng=en The unveiling in October 2004 of the remains of a pygmy-sized hominin recovered from a cave on the island of Flores, Indonesia, sparked an intense series of debates within the palaeoanthropology community. The discoverers diagnosed it to be a new species of Homo, which they called Homo floresiensis, and they interpreted the postcranial morphology as being 'consistent with human-like obligate bipedalism'. We have examined the morphology with the aim of determining whether biomechanical evidence supports the claim that this hominin-known as LB1-was indeed habitually bipedal. LB1's innominate bone differs from that of modern humans through the marked lateral flaring of the ilium, while her femur has a small head and a relatively long neck. Although these features are also found in australopithecines and are commonly regarded as 'primitive' traits, we concluded that none would have prevented her from exhibiting an efficient, bipedal gait. Having established that LB1 walked on two legs, we employed the principle of dynamic similarity to speculate how she might have walked. Assuming the gait of LB1 was dynamically similar to that of modern Homo sapiens, we used known dimensionless parameters, together with her leg length (0.55 m), to estimate her fundamental gait parameters: step length = 0.45 m, step frequency = 2.48 steps/second and speed = 1.11 m/s. Our review has provided insights regarding the way in which LB1 and her fellow diminutive hominins walked about the island of Flores over 18 000 years ago. <![CDATA[<b>South African research in the hydrological sciences</b>: <b>2003-2006</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500014&lng=en&nrm=iso&tlng=en The unveiling in October 2004 of the remains of a pygmy-sized hominin recovered from a cave on the island of Flores, Indonesia, sparked an intense series of debates within the palaeoanthropology community. The discoverers diagnosed it to be a new species of Homo, which they called Homo floresiensis, and they interpreted the postcranial morphology as being 'consistent with human-like obligate bipedalism'. We have examined the morphology with the aim of determining whether biomechanical evidence supports the claim that this hominin-known as LB1-was indeed habitually bipedal. LB1's innominate bone differs from that of modern humans through the marked lateral flaring of the ilium, while her femur has a small head and a relatively long neck. Although these features are also found in australopithecines and are commonly regarded as 'primitive' traits, we concluded that none would have prevented her from exhibiting an efficient, bipedal gait. Having established that LB1 walked on two legs, we employed the principle of dynamic similarity to speculate how she might have walked. Assuming the gait of LB1 was dynamically similar to that of modern Homo sapiens, we used known dimensionless parameters, together with her leg length (0.55 m), to estimate her fundamental gait parameters: step length = 0.45 m, step frequency = 2.48 steps/second and speed = 1.11 m/s. Our review has provided insights regarding the way in which LB1 and her fellow diminutive hominins walked about the island of Flores over 18 000 years ago. <![CDATA[<b>Recent research in seismology in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500015&lng=en&nrm=iso&tlng=en The unveiling in October 2004 of the remains of a pygmy-sized hominin recovered from a cave on the island of Flores, Indonesia, sparked an intense series of debates within the palaeoanthropology community. The discoverers diagnosed it to be a new species of Homo, which they called Homo floresiensis, and they interpreted the postcranial morphology as being 'consistent with human-like obligate bipedalism'. We have examined the morphology with the aim of determining whether biomechanical evidence supports the claim that this hominin-known as LB1-was indeed habitually bipedal. LB1's innominate bone differs from that of modern humans through the marked lateral flaring of the ilium, while her femur has a small head and a relatively long neck. Although these features are also found in australopithecines and are commonly regarded as 'primitive' traits, we concluded that none would have prevented her from exhibiting an efficient, bipedal gait. Having established that LB1 walked on two legs, we employed the principle of dynamic similarity to speculate how she might have walked. Assuming the gait of LB1 was dynamically similar to that of modern Homo sapiens, we used known dimensionless parameters, together with her leg length (0.55 m), to estimate her fundamental gait parameters: step length = 0.45 m, step frequency = 2.48 steps/second and speed = 1.11 m/s. Our review has provided insights regarding the way in which LB1 and her fellow diminutive hominins walked about the island of Flores over 18 000 years ago. <![CDATA[<b>Recent research in geomagnetism and aeronomy in South Africa</b>: <b>2003-2006</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532007000500016&lng=en&nrm=iso&tlng=en The unveiling in October 2004 of the remains of a pygmy-sized hominin recovered from a cave on the island of Flores, Indonesia, sparked an intense series of debates within the palaeoanthropology community. The discoverers diagnosed it to be a new species of Homo, which they called Homo floresiensis, and they interpreted the postcranial morphology as being 'consistent with human-like obligate bipedalism'. We have examined the morphology with the aim of determining whether biomechanical evidence supports the claim that this hominin-known as LB1-was indeed habitually bipedal. LB1's innominate bone differs from that of modern humans through the marked lateral flaring of the ilium, while her femur has a small head and a relatively long neck. Although these features are also found in australopithecines and are commonly regarded as 'primitive' traits, we concluded that none would have prevented her from exhibiting an efficient, bipedal gait. Having established that LB1 walked on two legs, we employed the principle of dynamic similarity to speculate how she might have walked. Assuming the gait of LB1 was dynamically similar to that of modern Homo sapiens, we used known dimensionless parameters, together with her leg length (0.55 m), to estimate her fundamental gait parameters: step length = 0.45 m, step frequency = 2.48 steps/second and speed = 1.11 m/s. Our review has provided insights regarding the way in which LB1 and her fellow diminutive hominins walked about the island of Flores over 18 000 years ago.