Showing papers in "South African Journal of Science in 2011"

A review of marine phylogeography in southern Africa

Abstract: The southern African marine realm is located at the transition zone between the Atlantic and Indo-Pacific biomes. Its biodiversity is particularly rich and comprises faunal and floral elements from the two major oceanic regions, as well as a large number of endemics. Within this realm, strikingly different biota occur in close geographic proximity to each other, and many of the species with distributions spanning two or more of the region’s marine biogeographic provinces are divided into evolutionary units that can often only be distinguished on the basis of genetic data. In this review, we describe the state of marine phylogeography in southern Africa, that is, the study of evolutionary relationships at the species level, or amongst closely related species, in relation to the region’s marine environment. We focus particularly on coastal phylogeography, where much progress has recently been made in identifying phylogeographic breaks and explaining how they originated and are maintained. We also highlight numerous shortcomings that should be addressed in the near future. These include: the limited data available for commercially important organisms, particularly offshore species; the paucity of oceanographic data for nearshore areas; a dearth of studies based on multilocus data; and the fact that studying the role of diversifying selection in speciation has been limited to physiological approaches to the exclusion of genetics. It is becoming apparent that the southern African marine realm is one of the world’s most interesting environments in which to study the evolutionary processes that shape not only regional, but also global patterns of marine biodiversity.

Spatial and temporal assessment of gaseous pollutants in the Highveld of South Africa

Abstract: Diverse natural and anthropogenic activities in the Highveld of South Africa contribute to elevated levels of inorganic and organic gaseous pollutant species. The primary aims of this investigation were to determine spatial and temporal distributions of nitrogen dioxide (NO 2 ), sulphur dioxide (SO 2 ) and ozone (O 3 ), as well as benzene, toluene, ethylbenzene and xylene (BTEX) in this area. Sampling was conducted on a monthly basis for a year at eight strategically selected sites. The highest NO 2 , SO 2 and BTEX concentrations were measured at sites with significant local sources and/or sites impacted by more remote sources, as indicated by overlay back trajectories. O 3 concentrations were found to be lower at sites with high levels of NO 2 , SO 2 and BTEX. NO 2 and SO 2 peaked during winter, while O 3 peaked in spring. NO 2 and SO 2 temporal concentration variations were ascribed to differences in seasonal meteorological conditions, as well as additional sources in winter. The O 3 peak coincided with a seasonal CO peak, which was identified as an important precursor for O 3 formation. No distinct seasonal trend was observed for BTEX. The annual average concentrations for SO 2 , NO 2 , O 3 and benzene were below the South African annual standards at all sites.

A review of shaped carbon nanomaterials

Abstract: Materials made of carbon that can be synthesised and characterised at the nano level have become a mainstay in the nanotechnology arena. These carbon materials can have a remarkable range of morphologies. They can have structures that are either hollow or filled and can take many shapes, as evidenced by the well-documented families of fullerenes and carbon nanotubes. However, these are but two of the shapes that carbon can form at the nano level. In this review we outline the types of shaped carbons that can be produced by simple synthetic procedures, focusing on spheres, tubes or fibres, and helices. Their mechanisms of formation and uses are also described.

The impact of acid mine drainage in South Africa : : commentary

Abstract: Acid mine drainage (AMD) has received considerable coverage in the media of late and the number of short courses and workshops devoted to the topic has mushroomed. The current interest was prompted mainly by concern arising from the decanting of contaminated water from the old gold mines in the Krugersdorp area into the Cradle of Humankind. This led to the establishment of an interministerial committee on AMD in late 2010. As part of this initiative, a technical task group was formed to investigate the problem and to recommend possible solutions. The report was finalised in December 2010, and focused primarily on the immediate problems arising from gold mining and in particular on the now defunct mines in the Western Basin (Krugersdorp area), the Central Basin (Roodepoort to Boksburg) and the Eastern Basin (Brakpan, Springs and Nigel area). However, the problem of AMD is of far wider extent and to understand it in its entirety it is necessary to take a much broader geographic view.

Land use and soil organic matter in South Africa 1: A review on spatial variability and the influence of rangeland stock production

Abstract: Degradation of soil as a consequence of land use poses a threat to sustainable agriculture in South Africa, resulting in the need for a soil protection strategy and policy Development of such a strategy and policy require cognisance of the extent and impact of soil degradation processes One of the identified processes is the decline of soil organic matter, which also plays a central role in soil health or quality The spatial variability of organic matter and the impact of grazing and burning under rangeland stock production are addressed in this first part of the review Data from uncoordinated studies showed that South African soils have low organic matter levels About 58% of soils contain less than 05% organic carbon and only 4% contain more than 2% organic carbon Furthermore, there are large differences in organic matter content within and between soil forms, depending on climatic conditions, vegetative cover, topographical position and soil texture A countrywide baseline study to quantify organic matter contents within and between soil forms is suggested for future reference Degradation of rangeland because of overgrazing has resulted in significant losses of soil organic matter, mainly as a result of lower biomass production The use of fire in rangeland management decreases soil organic matter because litter is destroyed by burning Maintaining or increasing organic matter levels in degraded rangeland soils by preventing overgrazing and restricting burning could contribute to the restoration of degraded rangelands This restoration is of the utmost importance because stock farming uses the majority of land in South Africa

Lake St Lucia, Africa's largest estuarine lake in crisis: Combined effects of mouth closure, low levels and hypersalinity

Abstract: The Lake St Lucia estuarine system is the most important nursery ground for juvenile marine fish and prawns along the KwaZulu-Natal coast. The estuary mouth closed in June 2002 because of drought and remained so for 4 years and 9 months. A study to determine the impacts of extended mouth closure, hypersalinity and low lake levels on the mesozooplankton, macrobenthic invertebrates and fish fauna was initiated in 2004. Zooplankton and benthic invertebrate diversity declined, benthic invertebrate community composition changed and the diversity and abundance of fish decreased between 2004 and 2007. In the case of fish, the declines were related to die-offs in the lake and the failed recruitment of post-larvae and juveniles from the marine environment as a result of the mouth having been closed. Options for management intervention under closed-mouth conditions are limited at this time, particularly in the short term, to breaching the mouth and facilitating the inflow of sea water. In the medium term, as was the historical situation, the reconnection of the Mfolozi system to St Lucia should be viewed as a major priority.

Land use and soil organic matter in South Africa 2: A review on the influence of arable crop production

Abstract: The decline of soil organic matter as a result of agricultural land use was identified for a review with the ultimate aim of developing a soil protection strategy and policy for South Africa. Such a policy is important because organic matter, especially the humus fraction, influences the characteristics of soil disproportionately to the quantities thereof present. Part 1 of this review dealt with the spatial variability of soil organic matter and the impact of grazing and burning under rangeland stock production. In this second part of the review, the impact of arable crop production on soil organic matter is addressed. A greater number of studies have addressed the degradation of soil organic matter that is associated with arable crop production than the restoration. However, cropping under dryland has been found to result in significant losses of soil organic matter, which is not always the case with cropping under irrigation. Restoration of soil organic matter has been very slow upon the introduction of conservational practices like zero tillage, minimal tillage, or mulch tillage. Reversion of cropland to perennial pasture has also been found to result in discouragingly slow soil organic matter restoration. Although increases or decreases in soil organic matter levels have occurred in the upper 300 mm, in most instances this took place only in the upper 50 mm. The extent of these changes was dependent inter alia on land use, soil form and environmental conditions. Loss of soil organic matter has resulted in lower nitrogen and sulphur reserves, but not necessarily lower phosphorus reserves. Depletion of soil organic matter coincided with changes in the composition of amino sugars, amino acids and lignin. It also resulted in a decline of water stable aggregates which are essential in the prevention of soil erosion. Although much is known about how arable crop production affects changes in soil organic matter, there are still uncertainties about the best management practices to maintain and even restore organic matter in degraded cropland. Coordinated long-term trials on carefully selected ecotopes across the country are therefore recommended to investigate cultivation practices suitable for this purpose.

A bibliometric analysis of South Africa's scientific outputs - some trends and implications

Abstract: The paper examines the change in volume of South African publications as indexed to the Web of Science over the periods 1990–1994 and 2004–2008. It was noted that publication volumes have increased sharply even while the stock of researchers has remained static. A number of factors may account for the rise including the increase in the Department of Education publication subsidy, the increase in the number of South African journals indexed to the Web of Science and a shift in focus to fields with higher publication propensity. For example, it was noted that a new growth area has emerged in the field of infectious diseases. The publication count by author institution showed that collaboration with foreign authors has increased considerably across the two periods and it is suggested that it is this factor that best accounts for the rise in volume. The concentration by subject area permitted some judgement to be made regarding the prospects for the five grand challenges of the Ten Year Innovation Plan. Lastly, it was noted that if it is collaboration that is driving the volume increase, the system is vulnerable to offshore changes.

The great shale debate in the Karoo

Abstract: Over the last year, rumours of vast cheap energy wealth stacked away beneath the Karoo have reached fever pitch. Apparently gas (methane - CH4) from shale is there for the picking - and they're said to be rich pickings. The extraction industry believes that we all will benefit from this fortune if we harvest it soon: indeed, it has been presented as a proverbial win-win situation. Alas, nothing could be further from the truth. Firstly, it is not known with any degree of certainty how much gas may be beneath the Karoo, and secondly, if there is enough, it is also uncertain whether the gas can be tapped without damaging other subsurface resources, particularly scarce potable water reservoirs, or without full rehabilitation of inevitable surface damage around the gas taps (or well heads). Two camps have emerged in the Karoo's 'great shale debate'. Conservationists argue that extraction of the gas will leave massive irreparable environmental scars on one of South Africa's iconic landscapes. And some of them have pointed to possible human health hazards from associated chemical pollution. According to this camp, we would all be better off leaving the gas in the ground - in a world of trade-offs, there are plainly none here.

Fusarium spp. and levels of fumonisins in maize produced by subsistence farmers in South Africa

Abstract: Fusarium spp. produce fumonisins – mycotoxins that are of importance to maize production in South Africa. Fumonisins have been associated with human oesophageal cancer and cause various diseases in animals that are of concern to the animal feed industry. Maize samples, collected from subsistence farm fields in the Eastern Cape, KwaZulu-Natal, Limpopo and Mpumalanga provinces of South Africa during the 2006 and 2007 growing seasons, were analysed for Fusarium spp. and contamination with fumonisins. Fusarium verticillioides was the most common Fusarium species in maize followed by F. subglutinans and F. proliferatum . Levels of contamination with fumonisins ranged from 0 μg/g to 21.8 μg/g, depending on the region where samples were collected. Levels of fumonisins were highest in northern KwaZulu-Natal (Zululand) where 52% and 17% of samples collected in 2006 and 2007, respectively, exceeded 2 μg/g. Regression analyses showed a positive correlation between fumonisin-producing Fusarium spp. determined by real-time polymerase chain reaction and concentration of fumonisins ( r = 0.93). Many samples from Zululand, and some from Mokopane (Limpopo) and Lusikisiki (Eastern Cape), contained fumonisins at levels well above the maximum levels of 2 μg/g set by the Food and Drug administration (USA) and therefore also the limit of 1 μg/g set by the European Union for food intended for direct human consumption. Regulations governing contamination of grain with fumonisins are not yet implemented in South Africa. The high incidence of fumonisins in subsistence farming systems indicates the need for awareness programmes and further research.

Patents and economic development in South Africa: managing intellectual property rights

Abstract: Intellectual property rights systems are important policy instruments in the armoury of governments. They have the potential to have favourable or adverse consequences for the relevant national system of innovation, technology transfer, research and development and, eventually, economic growth. Whilst there is a debate related to optimisation of patent systems in the developed world, there is limited debate related to the approaches used in developing countries like South Africa. This article presents an effort to assess whether the South African non-examining patent system makes a contribution or if it is detrimental to the country’s development. We found that the current intellectual property rights regime not only fails to support the objectives of the national innovation system but also that it facilitates exploitation by foreign interests and creates substantial social costs. Policy recommendations are provided.

Optical and electrical properties of NiO for possible dielectric applications

Abstract: Nickel oxide (NiO) is a versatile wide band gap semiconductor material. At present, transparent conducting oxide films find application as transparent electrodes and window coatings for opto-electronic devices but most are n -type. However p -type conducting films, of which NiO is one, are required as optical windows for devices where minority carrier injection is required. In this study, nickel (Ni) was resistively deposited on glass substrates and oxidised (isochronally) in oxygen at temperatures ranging from 300 ˚C to 600 ˚C. The oxidised Ni layers were subsequently characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-visible photospectrometry in the range 200 nm – 1000 nm. The four point probe method (van der Pauw geometry) was used to determine the sheet resistances of the oxidised films. SEM results of the surface revealed a strong dependence of the surface texture and particle size on the oxidation temperature and time. XRD performed on the oxidised Ni indicated progressive transformation from nanograined polycrystalline Ni to NiO at elevated temperatures. Film thicknesses, particle sizes, energy band gap and wavelength-dependent refractive indices were determined from transmission and absorbance data.

Vertebrate distributions indicate a greater Maputaland-Pondoland-Albany region of endemism

Abstract: The Maputaland-Pondoland-Albany (MPA) biodiversity hotspot (~274 316 km 2 ) was primarily recognised based on its high plant endemism Here we present the results of a qualitative biogeographical study of the endemic vertebrate fauna of south-eastern Africa, in an exercise that (1) refines the delimitation of the MPA hotspot, (2) defines zoogeographical units and (3) identifies areas of vertebrate endemism Initially we listed 62 vertebrate species endemic and 60 near endemic to the MPA hotspot, updating previous checklists Then the distributions of 495 vertebrate taxa endemic to south-eastern Africa were reviewed and 23 endemic vertebrate distributions (EVDs: distribution ranges congruent across several endemic vertebrate taxa) were recognised, amongst which the most frequently encountered were located in the Eastern Escarpment, central KwaZulu-Natal, Drakensberg and Maputaland The geographical patterns illustrated by the EVDs suggest that an expansion of the hotspot to incorporate sections of the Great Escarpment from the Amatola-Winterberg-Sneeuberg Mountains through the Drakensberg to the Soutpansberg would be justified This redefinition gives rise to a Greater Maputaland-Pondoland-Albany (GMPA) region of vertebrate endemism adding 135% more endemics with an increase of only 73% in surface area to the MPA hotspot The GMPA region has a more natural boundary in terms of EVDs as well as vegetation units An accurate delimitation of this hotspot, as well as a better understanding of biogeography in the region, would greatly benefit conservation planning and implementation Towards these aims, we used EVDs to delimit non-overlapping zoogeographical units (including 14 areas of vertebrate endemism), facilitating numerical biogeographical analyses More importantly, this study opens up possibilities of refining hotspot delimitation and identifying local conservation priorities in regions of the world where data do not allow numerical analyses

Atmospheric dry and wet deposition of sulphur and nitrogen species and assessment of critical loads of acidic deposition exceedance in South Africa

Abstract: We tested the hypothesis that acidic atmospheric pollution deposition, originating from the South African central industrial area, poses an environmental threat across a larger region within the dispersal footprint. A network of 37 passive monitoring sites to measure SO2 and NO2 was operated from August 2005 to September 2007. The area extended over the entire northern and eastern interior of South Africa. Monitoring locations were chosen to avoid direct impacts from local sources such as towns, mines and highways. Dry deposition rates of SO2 and NO2 were calculated from the measured concentrations. Concentrations of sulphur and nitrogen species in wet deposition from a previous study were used in conjunction with measured rainfall for the years 2006 and 2007 to estimate the wet deposition over the region. The calculated total (non-organic) acidic deposition formed the basis for an assessment of exceedance of critical loads based on sensitivity of the regional soils. Regional soil sensitivity was determined by combining two major soil attributes available in the World Inventory of Soil Emission Potentials (International Soil Reference and Information Centre). Results indicate that certain parts of the central pollution source area on the South African Highveld have the potential for critical load exceedance, while limited areas downwind show lower levels of exceedance. Areas upwind and remote areas up and downwind, including forested areas of the Drakensberg escarpment, do not show any exceedance of the critical loads.

A method for calculating the variance and confidence intervals for tree biomass estimates obtained from allometric equations

Abstract: The need for accurate quantification of the amount of carbon stored in the environment has never been greater. Carbon sequestration has become a vital component of the battle against global climate change, and monitoring and quantifying this process are major challenges for policymakers. Plant allometric equations allow managers and scientists to quantify the biomass contained in a tree without cutting it down, and therefore can play a pivotal role in measuring carbon sequestration in forests and savannahs. These equations have been available since the beginning of the 20th century, but their usefulness depends on the ability to estimate the error associated with the equations – something which has received scant attention in the past. This paper provides a method based on the theory of linear regression and the lognormal distribution to derive confidence limits for estimates of biomass derived from plant allometric equations. Allometric equations for several southern African savannah species are provided, as well as the parameters and equations required to calculate the confidence intervals. This method was applied to data collected from a sampling campaign carried out in a savannah landscape at the Skukuza flux site, Kruger National Park, South Africa. Here the error was 10% of the total site biomass for the woody biomass and 2% for the leaf biomass. When the data were split into individual plots and used to estimate site biomass (as would occur in most sampling schemes) the error increased to 16% and 12% of the woody and leaf biomasses, respectively, as the sampling errors were added to the errors in the allometric equation. These methods can be used in any discipline that applies allometric equations, such as health sciences and animal physiology.

Past approaches and future challenges to the management of fire and invasive alien plants in the new Garden Route National Park

Abstract: The recently established Garden Route National Park (GRNP) along the Cape south coast of South Africa occurs in a landscape where indigenous forests, fire-prone fynbos shrublands and fire-sensitive plantations of alien invasive trees are interspersed. We used the area as a case study in the challenges facing conservation managers in the achievement of biodiversity goals in a fire-prone environment. We explored the context within which fire management was practised during the past century by interviewing former catchment managers and reviewing forestry and catchment management policies. Mountain fynbos adjacent to plantations was subjected to burning regimes aimed at the protection of commercial timber resources rather than the preservation of fynbos biodiversity. Prescribed burning of fynbos adjacent to the plantations was typically done in multiple belt systems at rotations of about 4–8 years during spring, summer and autumn, to avoid the winter berg wind season. Such short-rotation and low-intensity fires favour resprouting graminoids over slow-maturing reseeders, and likely account for the compositional impoverishment observed in fynbos near plantations. Current and future challenges faced by the GRNP include (1) balancing conflicting fire management requirements for plantation safety against fynbos conservation; (2) the continual invasion of fynbos by fire-propagated alien pines sourced from plantations; (3) inadequate resources to redress the ‘invasion debt’ caused by the socio-economic legacy and past management neglect; and (4) fragmentation of land use between conservation and forestry threatening the sustainability of the region at large. We provide recommendations for management actions and research priorities to address these challenges.

Biofuels and biodiversity in South Africa

Abstract: The South African government, as part of its efforts to mitigate the effects of the ongoing energy crisis, has proposed that biofuels should form an important part of the country’s energy supply. The contribution of liquid biofuels to the national fuel supply is expected to be at least 2% by 2013. The Biofuels Industrial Strategy of the Republic of South Africa of 2007 outlines key incentives for reaching this target and promoting the development of a sustainable biofuels industry. This paper discusses issues relating to this strategy as well as key drivers in biofuel processing with reference to potential impacts on South Africa’s rich biological heritage. Our understanding of many of the broader aspects of biofuels needs to be enhanced. We identify key areas where challenges exist, such as the link between technology, conversion processes and feedstock selection. The available and proposed processing technologies have important implications for land use and the use of different non-native plant species as desired feedstocks. South Africa has a long history of planting non-native plant species for commercial purposes, notably for commercial forestry. Valuable lessons can be drawn from this experience on mitigation against potential impacts by considering plausible scenarios and the appropriate management framework and policies. We conceptualise key issues embodied in the biofuels strategy, adapting a framework developed for assessing and quantifying impacts of invasive alien species. In so doing, we provide guidelines for minimising the potential impacts of biofuel projects on biodiversity.

Ensuring the security and privacy of information in mobile health-care communication systems : research article

Abstract: The sensitivity of health-care information and its accessibility via the Internet and mobile technology systems is a cause for concern in these modern times. The privacy, integrity and confidentiality of a patient's data are key factors to be considered in the transmission of medical information for use by authorised health-care personnel. Mobile communication has enabled medical consultancy, treatment, drug administration and the provision of laboratory results to take place outside the hospital. With the implementation of electronic patient records and the Internet and Intranets, medical information sharing amongst relevant health-care providers was made possible. But the vital issue in this method of information sharing is security: the patient's privacy, as well as the confidentiality and integrity of the health-care information system, should not be compromised. We examine various ways of ensuring the security and privacy of a patient's electronic medical information in order to ensure the integrity and confidentiality of the information.

Ensuring the security and privacy of information in mobile health-care communication systems

Abstract: The sensitivity of health-care information and its accessibility via the Internet and mobile technology systems is a cause for concern in these modern times. The privacy, integrity and confidentiality of a patient’s data are key factors to be considered in the transmission of medical information for use by authorised health-care personnel. Mobile communication has enabled medical consultancy, treatment, drug administration and the provision of laboratory results to take place outside the hospital. With the implementation of electronic patient records and the Internet and Intranets, medical information sharing amongst relevant health-care providers was made possible. But the vital issue in this method of information sharing is security: the patient’s privacy, as well as the confidentiality and integrity of the health-care information system, should not be compromised. We examine various ways of ensuring the security and privacy of a patient’s electronic medical information in order to ensure the integrity and confidentiality of the information.

Past approaches and future challenges to the management of fire and invasive alien plants in the new Garden Route National Park : review article

Abstract: The recently established Garden Route National Park (GRNP) along the Cape south coast of South Africa occurs in a landscape where indigenous forests, fire-prone fynbos shrublands and fire-sensitive plantations of alien invasive trees are interspersed. We used the area as a case study in the challenges facing conservation managers in the achievement of biodiversity goals in a fire-prone environment. We explored the context within which fire management was practised during the past century by interviewing former catchment managers and reviewing forestry and catchment management policies. Mountain fynbos adjacent to plantations was subjected to burning regimes aimed at the protection of commercial timber resources rather than the preservation of fynbos biodiversity. Prescribed burning of fynbos adjacent to the plantations was typically done in multiple belt systems at rotations of about 4-8 years during spring, summer and autumn, to avoid the winter berg wind season. Such short-rotation and low-intensity fires favour resprouting graminoids over slow-maturing reseeders, and likely account for the compositional impoverishment observed in fynbos near plantations. Current and future challenges faced by the GRNP include (1) balancing conflicting fire management requirements for plantation safety against fynbos conservation; (2) the continual invasion of fynbos by fire-propagated alien pines sourced from plantations; (3) inadequate resources to redress the 'invasion debt' caused by the socio-economic legacy and past management neglect; and (4) fragmentation of land use between conservation and forestry threatening the sustainability of the region at large. We provide recommendations for management actions and research priorities to address these challenges.

Potential health effects of pesticide use on farmworkers in Lesotho

Abstract: This study examined the experiences of farmworkers during crop spraying in Lesotho. The main goal of this study was to determine the perceptions and awareness of farmworkers regarding the use of pesticides and the potential effects on their health. The data were obtained from farmworkers using a combination of an open-ended and a close-ended structured questionnaire in July 2006. Of the nine farms serviced by the Ministry of Agriculture and Food Security of Lesotho, Agricultural Research Division, six farms were randomly chosen and 27 farmworkers from these farms were interviewed. The data were analysed using descriptive statistics such as frequency tables. The results showed that farmworkers are relatively poorly educated and that a greater health risk is present when a lack of training and education on the use of pesticides also exists. That is, the majority (85%) of farmworkers did not have secondary education and most (93%) had no training on the use of pesticides, which poses a great health threat to the farmworkers. A lack of education makes it difficult for farmworkers to read and understand the information labels on pesticides and hence it is difficult for them to understand the health hazards of pesticides and the need for personal safety measures. When using and handling pesticides, 52% of farmworkers did not use rubber gloves and 93% did not use goggles or other forms of face cover. This lack of protection puts them at serious risk of skin exposure to pesticides. The farmworkers were quite aware of the harmful effects of pesticides, but were sometimes unable to translate this awareness into their own safety practices because of a lack of knowledge about the adverse effects. Therefore, training, extension services and various awareness programmes should be promoted in Lesotho in order to increase farmworkers’ knowledge and awareness of the adverse effects of pesticides on human health and the environment.

Gold coordination during homogeneous alkyne and allene cyclisation catalysis: Coordination to substrates, to ancillary ligands and in intermediates

Abstract: The ever-increasing role of homogeneous gold catalysis in organic synthesis and the consequent need to be able to rationally control the rate and outcome of such reactions has emphasised the importance of each successive metal–carbon coordination step. Concentrating on alkyne and allene cyclisation and upon reaction mechanisms postulated on the basis of empirical and theoretical results, we have examined the coordination of gold fragments to triple bonds, the modification of gold(I) precatalysts to effect specific reaction pathways or enantioselectivity and the isolation of coordinated intermediates or model compounds thereof. Some of the recent advances that have been made in various laboratories are described in this compact review.

The new growth path : game changing vision or cop-out? : commentary

Abstract: South Africa's 'new growth path' (NGP) plan aims to create 5 million jobs by 2020 and bring about a new more inclusive, labour-absorbing and efficient economy. The proposal is to achieve this through a mix of direct government job creation, social-democratic consensus building and macroeconomic, labour and industrial policies. It is a vision rather than a plan or a projection. Although a few specific objectives are listed (e.g. creating youth brigades in which a million young adults are to be provided with training and work experience), the NGP mainly takes the form of tabling a broad set of objectives (e.g. a more competitive, labour-absorbing, fast-growing, knowledge-intensive green economy which produces millions of decent jobs while reducing poverty and inequality) alongside an 'if then' commentary: if this vision is to be achieved then we need a stronger more efficient state, appropriately targeted policies, co-ordinated monetary and fiscal policies, an improved supply of skilled labour, co-operative partnerships with labour and capital, national will to accept some wage restraint and government mobilisation of savings and direction of investment etc. Precisely how important the various elements are is never spelled out.

Antidiabetic effects of Aloe ferox and Aloe greatheadii var. davyana leaf gel extracts in a low-dose streptozotocin diabetes rat model

Abstract: The medicinal use and commercialisation of the plants Aloe ferox and Aloe greatheadii are primarily based on research done on Aloe vera and Aloe arborescens. Consequently, in this study we investigated the possible antidiabetic effects of ethanol extracts of A. ferox and A. greatheadii var. davyana leaf gel in a streptozotocin (STZ)-induced type 2 diabetes rat model. Fifty male Wistar rats, weighing 200 g – 250 g, were randomly divided into five groups of n = 10: normal control rats, diabetic control rats, diabetic rats receiving A. ferox leaf gel extract (300 mg/kg), diabetic rats receiving A. greatheadii leaf gel extract (300 mg/kg), and diabetic rats receiving glibenclamide (600 μg/kg). Diabetes was induced by a single intraperitoneal injection of STZ (40 mg/kg). Rats were sacrificed 5 weeks after injection, following a 12-hour fast, and blood and tissue samples were collected. Compared to the normal control group, STZ significantly increased relative liver and kidney weights, end-point plasma glucose, fructosamine, oxidative stress, liver enzymes, total cholesterol (TC), triglycerides, very low density lipoproteincholesterol and TC: high density lipoprotein-cholesterol (HDL-C) values and reduced serum insulin levels. Treatment with A. greatheadii moderately increased serum insulin and HDL-C levels and moderately reduced end-point plasma glucose and liver alkaline phosphatase (ALP) and significantly decreased TC:HDL-C ratios. A. ferox supplementation similarly resulted in moderately increased serum insulin, accompanied by slight corrections in ALP and HDL-C, without any change to end-point plasma glucose values. A. greatheadii and, to a lesser extent, A. ferox, resulted in a clinically relevant improved diabetic state (indicated by moderate to high effect sizes), suggesting that these Aloe species may show promise for treating diabetes.

Hominin palaeoecology in Late Pliocene Malawi : first insights from isotopes (13C, 18O) in mammal teeth : research article

Abstract: Carbon-13 and oxygen-18 abundances were measured in large mammal skeletal remains (tooth enamel, dentine and bone) from the Chiwondo Beds in Malawi, which were dated by biostratigraphic correlation to ca. 2.5 million years ago. The biologic isotopic patterns, in particular the difference in carbon-13 abundances between grazers and browsers and the difference in oxygen-18 abundances between semi-aquatic and terrestrial herbivores, were preserved in enamel, but not in dentine and bone. The isotopic results obtained from the skeletal remains from the Chiwondo Beds indicate a dominance of savannah habitats with some trees and shrubs. This environment was more arid than the contemporaneous Ndolanya Beds in Tanzania. The present study confirms that robust australopithecines were able to live in relatively arid environments and were not confined to more mesic environments elsewhere in southern Africa.

The new growth path: Game changing vision or cop-out?

Abstract: South Africa's 'new growth path' (NGP) plan aims to create 5 million jobs by 2020 and bring about a new more inclusive, labour-absorbing and efficient economy. The proposal is to achieve this through a mix of direct government job creation, social-democratic consensus building and macroeconomic, labour and industrial policies. It is a vision rather than a plan or a projection. Although a few specific objectives are listed (e.g. creating youth brigades in which a million young adults are to be provided with training and work experience), the NGP mainly takes the form of tabling a broad set of objectives (e.g. a more competitive, labour-absorbing, fast-growing, knowledge-intensive green economy which produces millions of decent jobs while reducing poverty and inequality) alongside an 'if then' commentary: if this vision is to be achieved then we need a stronger more efficient state, appropriately targeted policies, co-ordinated monetary and fiscal policies, an improved supply of skilled labour, co-operative partnerships with labour and capital, national will to accept some wage restraint and government mobilisation of savings and direction of investment etc. Precisely how important the various elements are is never spelled out.

A failure by any other name : the phenomenon of underpreparedness : research article

Abstract: This study presents an analysis of the performance of students from disadvantaged schools (DS) on first-year psychology examination questions. The analysis focuses on the process of enquiry that underpins different kinds of questions (factual, relational and conceptual) of increasing levels of difficulty. The findings indicate that success or failure is not simply a measure of the reproduction of content but is a function of the (in)appropriate form of responses that students generate in engaging with different kinds of questions. This has important implications for the conceptualisation of academic literacy and the development of responsive curricula in the South African higher education context. In order to further understand the reasons for the disproportionately high failure rate among students from disadvantaged schools, the responses of DS failing students are compared to those of their peers from advantaged schools (AS) who also failed the course. This comparative analysis reveals very different patterns of questioning engagement among the two failing groups of students, providing empirical support for the argument that underpreparedness is a distinct systemic phenomenon rather than simply failure by another name.

Bibliometric analysis of public health research in Africa : the overall trend and regional comparisons : research article

Abstract: Many diseases in Africa can be prevented with appropriate public health interventions. This study aimed to assess the bibliometric characteristics of public health related research articles published by researchers in African institutions from 1991 to 2005. Data used in this study were obtained from the online version of the ISI Web of Science: Science Citation Index Expanded (SCI-Expanded). Articles published between 1991 and 2005 that had the phrase 'public health' in the title, author keywords or abstract, and had at least one author whose contact address was in an African country, were selected for analysis. The annual number of public health related articles published by African researchers significantly increased from 28 articles in 1991 to 135 articles in 2005, a 382% increase. International collaboration also increased: from 45% of articles having international collaborators during 1991-1995, to 52% during 1996-2000, and to 67% during 2001-2005. Collaborations were mostly with European and North American countries. Keywords, subject categories and collaboration patterns of articles varied across regions, reflecting differences in needs and collaboration networks. Public health related research output, as well as international collaborations, have been increasing in Africa. Regional variation observed in this study may assist policymakers to facilitate the advancement of public health research in different regions of Africa, and could be useful for international organisations in identifying needs and to allocate research funding. Future bibliometric analyses of articles published by African researchers, can consider conducting regional comparisons using standardised methods, as well as describing the overall patterns, in order to provide a more comprehensive view of their bibliometric characteristics.

Revealing yeast spore movement in confined space

Abstract: SOME YEASTS PRODUCE SEXUAL SPORES (ascospores) in a variety of shapes and surface ornamentations. These intriguing structures have hitherto been used only in yeast classification. Here, we propose the likely primary function of spore shape and ornamentations, in water-driven movement, as aiding the dispersal of the spores from enclosed containers (asci). This interpretation of the mechanics involved might find application in nano-, aeroand hydro-technologies with the re-scaling of these structures.