Scielo RSS <![CDATA[South African Journal of Science]]> http://www.scielo.org.za/rss.php?pid=0038-235320140001&lang=es vol. 110 num. 1-2 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>The statesman of education, science and technology</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100001&lng=es&nrm=iso&tlng=es <![CDATA[<b>Sentinels to climate change. The need for monitoring at South Africa's Subantarctic laboratory</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100002&lng=es&nrm=iso&tlng=es <![CDATA[<b>The distribution of the economic mineral resource potential in the Western Cape Province</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100003&lng=es&nrm=iso&tlng=es <![CDATA[<b>Using SNPs to find my roots</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100004&lng=es&nrm=iso&tlng=es <![CDATA[<b>Entomological evidence of misdemeanour</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100005&lng=es&nrm=iso&tlng=es <![CDATA[<b>Academic freedom as a keyword</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100006&lng=es&nrm=iso&tlng=es <![CDATA[<b>A new look at demographic transformation</b>: <b>Comments on Govinder et al. (2013)</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100007&lng=es&nrm=iso&tlng=es <![CDATA[<b>Mathematical errors, smoke and mirrors in pursuit of an illusion</b>: <b>Comments on Govinder et al. (2013)</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100008&lng=es&nrm=iso&tlng=es <![CDATA[<b>Flaws in the approach and application of the Equity Index</b>: <b>Comments on Govinder et al. (2013)</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100009&lng=es&nrm=iso&tlng=es <![CDATA[<b>Inflammation and cancer</b>: <b>The role of the human neutrophil</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100010&lng=es&nrm=iso&tlng=es Chronic inflammation of both infective and non-infective origin has been implicated in the aetiology of approximately 30% of all human epithelial malignancies. The primary carcinogens are reactive oxygen species (ROS) derived from activated, infiltrating cells of the innate immune system, especially neutrophils, which inflict oxidative damage on the DNA of bystander epithelial cells. The consequence is gene modifications which initiate cellular transformation. The process of tumourigenesis is exacerbated by the sustained generation of pro-proliferative ROS, as well as by the release of neutrophil-derived cytokines and proteases, all of which contribute to tumour promotion and progression. It is now well recognised that, in addition to inflammation causing cancer, many cancers per se induce an inflammatory response, with a high magnitude of neutrophil influx being indicative of a poor prognosis. In this setting, CXC chemokines produced by tumours not only promote neutrophil influx and hyperreactivity, but also cause autocrine activation of the proliferation of the chemokine-producing tumour cells. These various mechanisms of inflammation-mediated tumourigenesis are the primary focus of this review, together with a consideration of neutrophil-targeted anti-inflammatory strategies with potential as adjunctive cancer therapy. <![CDATA[<b>Responsible conduct of research</b>: <b>Global trends, local opportunities</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100011&lng=es&nrm=iso&tlng=es Instances of research misconduct reported in the lay and scientific literature as well as international efforts to encourage research integrity and the responsible conduct of research are currently receiving considerable attention. In South Africa, however, the topic has not featured prominently in public debate and clear evidence of a national, coordinated effort to address the problem of research misconduct seems to be lacking. Given increasing globalisation of research efforts, the need exists to promote standardised approaches to interpretation and implementation of the principles and values that underlie responsible conduct of research as well as to create guidelines and structures to promote integrity in research in the country. We explore the notions of research misconduct and research integrity, focusing on initiatives that promote responsible conduct of research, and propose a framework for the South African context. <![CDATA[<b>Shedding light on spectrophotometry</b>: <b>The SpecUP educational spectrophotometer</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100012&lng=es&nrm=iso&tlng=es Students often regard laboratory instruments as 'black boxes' which generate results, without understanding their principles of operation. This lack of understanding is a concern because the correct interpretation of analytical results and the limitations thereof is invariably based on an understanding of the mechanism of measurement. Moreover, a number of tertiary institutions in Africa have very limited resources and access to laboratory equipment, including that related to the field of photonics, which prevents students from acquiring hands-on practical experience. We address both of these challenges by describing how students can assemble a novel, low-cost spectrophotometer, called the SpecUP, which can then be used in a range of experiments. The same kind of information can be generated as that obtained with costly commercial spectrophotometers (albeit of a lower quality). With the SpecUP, students also have the opportunity to vary instrumental parameters and to observe the effects these changes have on their experimental results, allowing for enquiry-based learning of spectroscopic principles. The results obtained for some chemistry-related spectrophotometric experiments are described for each of the two operational modes of the SpecUP although the instrument can be applied in fields ranging from physics to biochemistry. <![CDATA[<b>A centrifugal microfluidic platform for point-of-care diagnostic applications</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100013&lng=es&nrm=iso&tlng=es Microfluidic systems enable precise control over tiny volumes of fluid in a compact and low-cost form, thus providing the ideal platform on which to develop point-of-care diagnostic solutions. Centrifugal microfluidic systems, also referred to as lab-on-a-disc or lab-on-a-CD systems, provide a particularly attractive solution for the implementation of microfluidic point-of-care diagnostic solutions as a result of their simple and compact instrumentation, as well as their functional diversity. Here we detail the implementation of a centrifugal microfluidic platform - the first of its kind in South Africa - as a foundation for the development of point-of-care diagnostic applications for which both the need and impact is great. The centrifugal microfluidic platform consists of three main components: a microfluidic disc device similar in size and shape to a CD, a system for controlling fluid flow on the device, and a system for recording the results obtained. These components have been successfully implemented and tested. Preliminary test results show that microfluidic functions such as pumping and valving of fluids can be successfully achieved, as well as the generation of monodisperse microfluidic droplets, providing a complete centrifugal microfluidic platform and the building blocks on which to develop a variety of applications, including point-of-care diagnostics. The lab-on-a-disc platform has the potential to provide new diagnostic solutions at the point-of-need in health- and industry-related areas. This paves the way for providing resource limited areas with services such as improved, decentralised health-care access or water-quality monitoring, and reduced diagnosis times at a low cost. <![CDATA[<b>Sunspot numbers</b>: <b>Implications on Eastern African rainfall</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100014&lng=es&nrm=iso&tlng=es Following NASA's prediction of sunspot numbers for the current sunspot cycle, Cycle 24, we now include sunspot numbers as an explanatory variable in a statistical model. This model is based on fitting monthly rainfall values with factors and covariates obtained from solar-lunar geometry values and sunspot numbers. The model demonstrates high predictive skill in estimating monthly values by achieving a correlation coefficient of 0.9 between model estimates and the measurements. Estimates for monthly total rainfall for the period from 1901 to 2020 for Kenya indicate that the model can be used not only to estimate historical values of rainfall, but also to predict monthly total rainfall. We have found that the 11-year solar sunspot cycle has an influence on the frequency and timing of extreme hydrology events in Kenya, with these events occurring every 5±2 years after the turning points of sunspot cycles. While solar declination is the major driver of monthly variability, sunspots and the lunar declinations play a role in the annual variability and may have influenced the occurrence of the Sahelian drought of the mid-1980s that affected the Sahel region including the Greater Horn of Africa. Judging from the reflection symmetry, the trend of the current maximum and the turning point of the sunspot minimum at the end of the Modern Maximum, with a 95% level of confidence, drought conditions similar to those of the early 1920s may reoccur in the year 2020±2. <![CDATA[<b>The impact of accent identification errors on speech recognition of South African English</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100015&lng=es&nrm=iso&tlng=es For successful deployment, a South African English speech recognition system must be capable of processing the prevalent accents in this variety of English. Previous work dealing with the different accents of South African English has considered the case in which the accent of the input speech is known. Here we focus on the practical scenario in which the accent of the input speech is unknown and accent identification must occur at recognition time. By means of a set of contrastive experiments, we determine the effect which errors in the identification of the accent have on speech recognition performance. We focus on the specific configuration in which a set of accent-specific speech recognisers operate in parallel, thereby delivering both a recognition hypothesis as well as an identified accent in a single step. We find that, despite their considerable number, the accent identification errors do not lead to degraded speech recognition performance. We conclude that, for our South African English data, there is no benefit of including a more complex explicit accent identification component in the overall speech recognition system. <![CDATA[<b>Dynamics of arable land requirements for food in South Africa</b>: <b>From 1961 to 2007</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100016&lng=es&nrm=iso&tlng=es Food consumption puts pressure on natural resources and arable land. In the present study, we examined the dynamics of land requirements for food in South Africa from 1961 to 2007 and investigated the relationships between dietary patterns, yield, cropping intensity, population and the area of required land using the thought experiment method. Strong population growth and the development of agricultural technology (indicated by yield) accounted for more than a 2.5-fold increase in the total land requirements for food from 1961 to 2007. Before the 1990s, the increase in crop yields enabled constant land requirements, whereas, after the 1990s, the combined effect of agricultural technology and population growth, together with a small contribution from dietary changes, led to an increase in the land requirements for food. Our findings confirm that the variation in land requirements for food is a complex, non-linear function of agricultural production techniques, population growth and dietary patterns and show that the complex relationship between dietary pattern changes, and economic development challenges future predictions of land requirements for food in South Africa. <![CDATA[<b>The first-year augmented programme in Physics</b>: <b>A trend towards improved student performance</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100017&lng=es&nrm=iso&tlng=es Amidst a critical national shortage of qualified Black graduates in the pure and applied sciences, the University of KwaZulu-Natal has responded to a call from government for redress by launching the BSc4 Augmented Physics programme. In this paper, the methods employed to foster learning and to encourage student success in the Mechanics module of the Augmented Physics programme are described and discussed. The use of problem-based learning and a holistic learning policy that focuses on the emotional, physical and knowledge development of the student seems to have yielded higher throughput in the first semester of an undergraduate programme in Physics. Furthermore, the results point to an increase in the conceptual understanding of the student with respect to Mechanics. When appraising this success, the results of the 2007-2009 cohorts, with and without teaching interventions in place, were analysed. These initial analyses pave the way for a course designed to benefit the student and improve throughput. These methods are not unique to Physics and can be adapted for any module in any country. <![CDATA[<b>A late Holocene sea-level curve for the east coast of South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532014000100018&lng=es&nrm=iso&tlng=es South Africa's extensive and topographically diverse coastline lends itself to interpreting and understanding sea-level fluctuations through a range of geomorphological and biological proxies. In this paper, we present a high-resolution record of sea-level change for the past ~1200 years derived from foraminiferal analysis of a salt-marsh peat sequence at Kariega Estuary, South Africa. A 0.94-m salt-marsh peat core was extracted using a gouge auger, and chronologically constrained using five radiocarbon age determinations by accelerator mass spectrometry, which places the record within the late Holocene period. Fossil foraminifera were analysed at a high downcore resolution, and a transfer function was applied to produce a relative sea-level reconstruction. The reconstructed sea-level curve depicts a transgression prior to 1100 cal years BP which correlates with existing palaeoenvironmental literature from southern Africa. From ~1100 to ~300 cal years BP, sea levels oscillated (~0.5-m amplitudes) but remained consistently lower than present-day mean sea level. The lowest recorded sea level of -1±0.2 m was reached between 800 and 600 cal years BP. After 300 cal years BP, relative sea level has remained relatively stable. Based on the outcomes of this research, we suggest that intertidal salt-marsh foraminifera demonstrate potential for the high-resolution reconstruction of relative sea-level change along the southern African coastline.