bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution and habitats of Gyraulus costulatus, potential snail intermediate host of intestinal flukes of the family Echinostomatidae in South Africa
Authors: De Kock K.N. , Wolmarans C.T.
Published: August 2012

This paper focuses on the geographical distribution and habitats of Gyraulus costulatus as reflected by the 736 localities currently on record in the database of the National Freshwater Snail Collection (NFSC) of South Africa. Although a wide variety of water body types was reported for this species, the largest number of samples were yielded by rivers, streams and dams which were described as perennial with predominantly fresh and clear water. A mainly stony substrate and the presence of aquatic vegetation were recorded for the majority of localities at the time of survey. An integrated decision tree constructed from the data indicated that altitude, temperature and water bodies were the most important of the factors investigated that determined the documented geographical distribution of this species in South Africa. This was supported by the effect size values calculated separately for each factor. Since the early eighties of the previous century, surveys to monitor and update the geographical distribution of freshwater snails and snail-borne parasitic diseases have been relegated to a low priority issue and this is a matter of concern. It is recommended that the exact role of G. costulatus in the epidemiology of economically important helminth parasites in South Africa should be investigated.
Determining heart rate variation: a comparison between direct results from V6 of the ECG and time domain, frequency domain and non-liniar analysis
Authors: Grant C. , Becker P. J. , Viljoen M.
Published: August 2012

Oscillation around a mean value is found in the intervals between consecutive heartbeats (R-R intervals). This oscillation is known as heart rate variability (HRV). Various methods can be used to estimate HRV, but the extent to which agreement exists between the results obtained by the different methods is not known. In this study HRV, as determined directly from the ECG, is compared to results obtained by time domain analysis, frequency domain analysis, Poincaré graphs and fractal analysis. Results showed that, in individuals with low HRV values, the results obtained by time domain analysis, frequency domain analysis, Poincaré graphs and alpha 1 of fractal analysis are comparable to those calculated directly from the ECG. However, time domain analysis, frequency domain analysis, Poincaré graphs and fractal analysis are less sensitive than direct ECG measurements in individuals with higher HRV.
Philosophical tendencies in the genesis of our understanding of physical nature
Authors: Strauss D. F. M.
Published: August 2012

The rise of a long-standing legacy of natural scientific thought is found in ancient Greece – the well-spring of Western civilization and the source of articulated rational reflection. The earliest phase of Greek culture already gave birth to theoretical thinking about the universe. The Pythagoreans are first of all famous for their emphasis on number as a mode of explanation. However, in their thesis that everything is number they solely acknowledged rational numbers (fractions) and this approach eventually stranded on the discovery of irrational numbers that led to the geometrization of Greek mathematics. This transition generated at once also a powerful space metaphysics overarching the entire medieval period. It was only during the early modern period that the predecessors and successors of Galileo contemplated an appreciation for motion as a new principle of explanation (compare the classical mechanistic world view of the universe as a mechanism of material particles in motion). But also this mechanistic reduction (through which all physical processes were reduced to the motion of charged or uncharged mass-points) eventually failed because it was unable to account for the irreversibility of physical processes. As a result it was only 20th century physics that managed to acknowledge the decisive qualifying role of energy-operation (thus of the physical aspect) in the existence of material things and processes. This article is concluded with an explanation of the significance of the preceding considerations for a theoretical approximation of the mysterious nature of matter.
The competitive platform for industrial development in South Africa
Authors: Kleynhans E. P. J.
Published: August 2012

The competitive platform of South African industries was investigated in this study. The theoretical foundation of industrial development policy and industrial location was considered first, followed by an empirical investigation of the competitive platform of manufacturing industries.
Two-dimensional generator function for the vector cardiogram for use in volume conduction models of the thorax
Authors: Geldenhuys T. A. , Joubert M. , Viljoen S. , Hanekom T.
Published: August 2012

An electrocardiogram (ECG) measures the electrical activity of the heart on the surface of the skin. Volume conduction models of the thorax can be designed to simulate such measurements. However, to drive such simulations a generator function is required to describe the electrical activity of the heart. Although such simulations, varying in complexity, are discussed in literature, there is a need for a simplified, though comprehensive approach that can be used as a concise introduction to this topic, or for cases where one is primarily interested in first-order approximations of this problem. In this article an overview of the vector interpretation of the ECG, also known as a vector cardiogram (VCG), is presented in the two-dimensional frontal plane of a human. The derivation of the equivalent electric dipole (i.e. the cardiac vector) from the VCG, which can be used as a current-source generator function for volume conduction model simulating the ECG, is discussed. A procedure for implementing such a volume conduction model with the finite element technique, using this simplified two-dimensional generator function, is discussed and the results are presented. The general features observed in recorded ECG leads agree with those predicted by this simple model.
The compounds and biological activity of Thamnosma africana
Authors: Mafokane H. F. , Potgieter N. , Van Ree T.
Published: August 2012

The aerial parts and fruits of Thamnosma africana were investigated for chemical compounds present in them. The volatile oil of T. africana was prepared by hydrodistillation of leaves, flowers and stems, and characterized by GC-MS. The oil was tested for antimicrobial activity on cultures of E. coli, B. subtilis and S.aureus, and found to inhibit Bacillus subtilis and Staphylococcus aureus at 0.1% dilution. The oil was also active against Plasmodium falciparum in micromolar concentrations. Chromatographic separation of the ethyl acetate extract of the aerial parts yielded two isomers of methoxypsoralen (xanthotoxin and bergapten) and 6-(1c,2c-dihydroxy-3c-methyl-3c-butenyl)-7-methoxychromen-2-one (thamnosmonin). The epoxide of thamnosmonin, 6-(1c,2c-epoxy-3c-methylbut-3c-en-1c-yl)-7-methoxychromen-2-one (thamnosmin), and methyl p-isopentenyloxycinnamate were isolated from the hexane extract of the fruits, while another furanocoumarin, 4,9-dimethoxy-7H-furo[3,2-g]benzopyran-7-one (isopimpinellin) was isolated from a dichloromethane extract of the aerial parts.
The implications of reading en writing language preference with regard to internet access for users in South Africa
Authors: Blignaut Pieter , Mcdonald Theo
Published: August 2012

For historical reasons, English is the language of the internet. Currently, e-commerce attracts customers from all over the world. In order to do good business, websites must be accessible to clients from a variety of cultures and languages. To achieve usability for a global audience, websites must be internationalized as well as localized. Given the many cultures and idiosyncrasies of those cultures, both of these tasks are extremely complex and it is virtually impossible to do both at the same time. It could be helpful if some cultures do not object to the fact that the language of the internet is not the same as their home language. In this study the preferred language of reading and writing of various groupings of African users was determined. It was found that, whereas the Afrikaans-speaking subjects preferred to have written material in their home language, speakers of other African languages preferred English. This has enormous implications for website development as developers can focus on the usability and functionality of a site without having to spend time translating the content into a variety of languages.
An investigation regarding metacognition in the learning of mathematics in the senior phase
Authors: Van der Walt M. G. , Maree J. G. , Ellis S. M.
Published: August 2012

South African learners’ insufficient achievement in mathematics is a source of great concern. This is especially the case since mathematics is regarded as a vital life skill in the postmodern, technologically sophisticated era. The concept “metacognition” is referred to both directly and indirectly in the Critical Outcomes in Curriculum 2005 – after all, most of the outcomes referred to imply that learners should be directed to reflect on their own thoughts. The primary aim of this study was to investigate the possible value of metacognition for the learning of mathematics. Both quantitative and qualitative research methods were implemented. The findings indicate, inter alia, that the metacognitive strategies with regard to prediction, evaluation, monitoring and reflection of learners in the research group are insufficient.
Funksionele beskrywing van ’n faktor VIIa inhiberende peptied, IP-7, geselekteer deur faagblootleggingstegnologie
Authors: Meiring S.M. , Roets C.E. , Badenhorst P.N.
Published: August 2012

Die tegniek van faagblootlegging is gebruik om ’n sikliese heptapeptied te selekteer wat met weefselfaktor(WF) kompeteer vir binding aan stollingsfaktor VIIa. Die aminosuurvolgorde van die peptied is Cys-Ala- Trp-Pro-His-Thr-Pro-Asp-Cys (C-AWPHTPD-C) en dit verleng die protrombientyd (PT) op ’n konsentrasie-afhanklike wyse. Die peptied beperk plaatjieklewing aan beide menslike endoteelsel- en weefselfaktormatrikse in ’n vloeikamermodel onder arteriële vloeitoestande. Die peptied funksioneer as ’n volledig mededingende inhibeerder van faktor VIIa met ’n inhibisiekonstante (Ki) van 123,2 μM. In sy huidige vorm is die peptied waarskynlik nie sterk genoeg om verder as antitrombotiese middel ontwikkel te word nie, maar verskillende strategieë kan gevolg word om die werking daarvan te versterk. AbstractFunctional characterisation of a factor VIIa inhibiting peptide, IP-7 selected by phage display technology By using the technique of phage display, we selected a cyclic heptapeptide sequence Cys-Ala-Trp-Pro-His-Thr-Pro-Asp-Cys (C-AWPHTPD-C) that competes with tissue factor for binding to coagulation factor VII. This peptide prolongs the prothrombin time (PT) in a concentration dependent way. It also reduces platelet adhesion to both human endothelial cell and tissue factor matrixes in a flow chamber under arterial flow conditions. Furthermore, it acts as a full competitive inhibitor of factor VIIa with an inhibition constant (Ki) of 123,2 μM. In its current form the peptide is probably not sufficiently potent for development as an antithrombotic agent, but different strategies could be followed to reinforce its performance.
Bioprospecting, legislation and research at universities in South Africa
Authors: Du Plessis J.L.
Published: August 2012

South Africa is particularly rich in biodiversity. This biodiversity may be utilised and has commercial potential. Bioprospecting is the systematic evaluation of biodiversity by making use of advanced technologies in search of and development of commercially, valuable new products. The international Convention on Biodiversity and the national Biodiversity Act accentuate the sustainable use and conservation of biodiversity and set certain prerequisites for bioprospecting and the research concerned with it. Research with indigenous biological resources is also affected by this legislation. Almost every university in South Africa is involved in bioprospecting projects and/or research with indigenous biological resources. A short overview of the origin of the Biodiversity Act is given. Research management and researchers are hereby informed of the current legal implications of the Biodiversity Act on research at universities.
Swartwattelbome: seën of vloek vir Suid- Afrika?
Authors: Smith F.H.
Published: August 2012

Daar is reeds baie geskryf oor uitheemse indringerplante, veral Acacia mearnsii De Wild, die swartwattelboom en die skade wat hierdie plante aan die plaaslike ekologie aanrig. In hierdie artikel word aandag gegee aan die ontstaan van die probleem, asook aan die inbring en verspreiding van swartwattelbome in die Republiek van Suid-Afrika (Suid-Afrika). Die probleme wat deur die onbeheerde verspreiding van wattelbome veroorsaak is, het die regering verplig om op te tree ten einde hierdie probleme te bekamp. Voor 1936 was daar aanvanklik geen formele beleid met betrekking tot die invoer, kweek en beheer van hierdie bome nie. Dit het daartoe gelei dat die regering in die wattelbedryf ingegryp het om ’n sekere mate van beheer te vestig en om probleme met betrekking tot uitheemse indringerplante in die algemeen – en die swartwattelboom in die besonder – die hoof te bied. Voorts sal daar ook gelet word op die rol van swartwattel in volhoubare ontwikkeling deur te fokus op die omgewings-/ekologiese probleem van impak op die biodiversiteit en die waterbronne en ook op die voordele wat dit het om woudherstel aan te help. Die artikel bespreek sosiale voordele wat die boom het vir inwoners van landelike gebiede as voorsiener in bou- en konstruksiemateriaal en vuurmaakhout, wat andersins uit die boomveld en/of inheemse woude verkry moet word. Die boom voorsien ook in die houtbehoeftes van die industrie in die vorm van byvoorbeeld pale, pulp en ekstrak. Laastens volg ’n bespreking van die Werk-vir-Water-program. AbatractBlack wattle trees: blessing or curse to South Africa Much has been written about alien invasive plants, especially Acacia mearnsii De Wild, the black wattle tree and the damage done by these plants to the local ecology. In this article cognisance is taken of how the problem was created, the introduction into and the distribution of black wattle trees in the Republic of South Africa (South Africa). Problems experienced by the uncontrolled spreading of wattle trees forced the government to act, as there was no formal policy before 1936 on the importation, cultivation and control thereof. This led to intervention by government in the wattle industry to establish some form of control and to address the problems related to alien invasive plants in general, and the black wattle tree in particular. Furthermore, cognisance will be taken of the role the black wattle plays in sustainable development by considering the environmental/ecological problem of its impact on bio-diversity and the water sources as well as the advantages it has in the process of forest recovery. Secondly notice will be taken of the social advantages the tree has for the inhabitants of rural areas as a provider of building and construction material and firewood, which would otherwise come from the woodlands and/or indigenous forests. The tree also provides in the timber requirements of industry in the form of for instance poles, pulp and extract. Lastly, the article explores the Work-for-Water Programme.
The highly unsaturated fatty acids: physiological role and clinical possibilities
Authors: Haag M. , Coetzee M.
Published: August 2012

Fatty acids play a very important role in human physiology. Except for the fact that fatty acids in stored triglycerides can be used for energy production, fatty acids from dietary lipids are transported in plasma and built into various cellular structures. The fatty acid profile of cell membrane phospholipids plays a determining role in the cell membrane in that it influences fluidity, receptor function and the type of eicosanoids that can be synthesised from it. Fatty acids also have highly differentiated inputs in cellular transduction mechanisms and regulation of gene transcription. In this, the steric conformation plays a large role: the straight-chain saturated and trans-fatty acids, when compared with the unsaturated fatty acids with progressively more bent chains, lead to a variety of mechanisms that have less positive effects on our health. In this regard, the two most important families of polyunsaturated fatty acids, the so-called omega-3 and omega-6 fatty acids, also lead to different effects. Changes in the pattern of dietary fatty acid intake through the ages have lead to an increased intake of saturated, trans- and omega-6 fatty acids relative to omega-3 fatty acids. Clinical trials during the past twenty years have shown that dietary supplementation with omega-3 fatty acids can lead to an improvement of the symptoms of certain lifestyleassociated disorders. Atherosclerosis, obesity, type 2 diabetes mellitus, depression, schizophrenia, Alzheimer’s disease, attention deficit hyperactivity disorder in young children, certain types of cancer, osteoporosis in the elderly and some dermatological disorders are amongst the conditions that can be addressed in this manner.
Vital soil as basis for sustainable soil management, a survey of soil problems in The Netherlands and the way to tackle it, with an assessment for the South African situation
Authors: Eijsackers H. , Maboeta M. , Doelman P.
Published: August 2012

In the past decades, soils in South Africa as well as The Netherlands have become increasingly deteriorated as a result of chemical and physical factors. Soil contamination, acidification, desiccation and erosion have caused negative impacts on land surfaces which are still on the increase. Soil functions like primary plant production, natural soil water clean up, basis and substrate for the above ground biodiversity and food chains, have become completely or partially impaired. The awareness, that soil is a vital and living system has to become the basis of soil policy and soil management. This paper is a plea for such an approach. It describes the various threats, what a vital soil is and which factors play a key role in this vital system: soil structure, buffer capacity, organic matter content, and the variety of soil organisms. It also indicates how the vitality of the soil should be monitored.
A generalised Sylvester-Gallai Theorem
Authors: Pretorius L. M. , Swanepoel K. J.
Published: August 2012

We give an algorithmic proof for the contrapositive of the following theorem that has recently been proved by the authors:Let S be a ﬁnite set of points in the plane, with each point coloured red, blue or with both colours. Suppose that for any two distinct points A and B in S sharing a colour k, there is a third point in S which has (inter alia) the colour different from k and is collinear with A and B. Then all the points in S are collinear.This theorem is a generalization of both the Sylvester-Gallai Theorem and the Motzkin-Rabin Theorem.
The anatomy of startle
Authors: Panzer Annie , Lambert Stephen
Published: August 2012

The involuntary startle is part of the first rapid fear reactions an organism experiences in response to a sudden threatening stimulus. It is adaptive in the sense that it allows the organism to immediately withdraw from an object that might possibly be dangerous, while the higher centres of the brain are still busy processing whether the object is in fact dangerous. The involuntary startle reaction is colloquially described as “to jump with fright”. This hair-trigger system is fine-tuned to protect organisms from danger and tends to err on the side of caution. Therefore, everyone has probably jumped with fright in response to an entirely harmless stimulus, for example mistaking a twig for a snake. This paper aims to explain why and how we jump with fright, even though we realise only milliseconds later that it was completely unnecessary to get a fright at all. The fear centres of the brain are the amygdala, two small nuclei in the limbic system. Visual, auditory and olfactory input from the sensory organs is relayed to the amygdala via two different pathways. Like most types of sensory inputs to the brain the information that activates the fear response via the indirect route is routed via the thalamus to cortical areas where it is analysed in terms of previous experience quality and context. From here the analysed information reaches the amygdala – the cerebral structures generally associated with fear. Impulses from the amygdala will then stimulate the typical fear reactions. In contrast to the indirect route from thalamus to amygdala just described, a direct route is taken in the case of the startle reaction. Impulses from the thalamus are relayed directly to the amygdala and the person experiences the fear reaction and response before the information has been analysed by the cortical structures. This short-cut to the amygdala is a direct, fast and crude pathway from the senses through the relevant modalities to the thalamus to the central nucleus of the amygdala. In general its purpose is to prime the amygdala for detailed incoming information, but in conditions of sudden danger it provides for a rapid response to a potentially aversive situation. The advantage of the direct pathway is that it allows for a quicker reaction, almost half the time that it takes for the cortical input pathway to the amygdala. The startle reaction is essential when speed is more important than accuracy, for example, when a life may be at stake. The cortical pathway is indirect, slower and refined, which allows for cortical processing and thus a much more accurate presentation of the stimulus. This route can also inhibit an inappropriate fear response initiated through the direct route. In this paper the neuroanatomy, specifically explaining the direct and indirect (cortical) route by which perceptual information reaches the amygdala, is reviewed first. Then the physiology of the fear reaction is alluded to, after which we conclude with an integrating figure and state a few interesting implications.
Transcending logic: the difference between contradiction and antinomy
Authors: Strauss Daniël
Published: August 2012

Philosophy and all the academic disciplines are sensitive to the aim of sound reasoning – except for the dialectical tradition which sanctions contradictions and antinomies (Heraclitus, Nicolas of Cusa, Hegel, Marx, Vaihinger, Simmel, Rex, and Dahrendorf). A brief overview is presented of conflicting theoretical stances within the various academic disciplines before an assessment is given of the positive and negative meaning of ‘reductionism.’ Against the background of historical lines of development the multiple terms employed in this context are mentioned and eventually positioned within the context of the normativity holding for logical thinking. It is argued that the logical contrary between logical and illogical serves as the foundation of other normative contraries, such as legal and illegal and moral and immoral. Through the discovery of irrational numbers the initial Pythagorean conviction that everything is number reverted to a geometrical perspective that generated a static metaphysics of being which challenged the ideas of plurality and motion. This development uncovered the problem of primitive terms in scientific discourse as an alternative for those theoretical attempts aimed at reducing whatever there is to one single mode of explanation. Zeno’s paradoxes are used to demonstrate an alternative understanding of the difference between the potential and the actual infinite as well as the nature of (theoretical) antinomies. It is argued that genuine antinomies are inter-modal in nature (such as is found in the attempt to reduce movement to static positions in space) and therefore differ from logical contradictions (such as a ‘square circle’ which merely confuses two figures within one modal aspect). Although every antinomy does entail logical contradictions, the latter do not necessarily presuppose an antinomy. The implication is that logic itself has an ontic foundation – as is seen from the nature of the principle of sufficient reason (ground) and the principle of the excluded antinomy – and therefore only acquires meaning on the basis of a non-reductionist ontology. When the method of immanent critique unveils genuine antinomies, the way is opened for meaningful intellectual interaction between different philosophical stances. In distinguishing between contradiction and antinomy philosophers are actually challenged to contemplate the implications of a non-reductionist ontology, such as avoiding the stance of monistic isms.
In vitro effekte van 2-metoksiëstradiol op selgetalle, morfologie en geenuitdrukking in ’n borsepiteelkarsinoomsellyn
Authors: Office Editorial
Published: August 2012

Geen Abstrakt.
Die groot avontuur – wondere van lewe op aarde
Authors: Barnard Barnie
Published: August 2012

No abstract
Incorporating biomarkers in ecological risk assessment of chemical contaminants of soils
Authors: Reinecke A. J. , Reinecke S. A. , Maboeta M. S. , Odendaal J. P. , Snyman R.
Published: August 2012

Soil is an important but complex natural resource which is increasingly used as sink for chemicals. The monitoring of soil quality and the assessment of risks posed by contaminants have become crucial. This study deals with the potential use of biomarkers in the monitoring of soils and the assessment of risk resulting from contamination. Apart from an overview of the existing literature on biomarkers, the results of various of our field experiments in South African soils are discussed. Biomarkers may have potential in the assessment of risk because they can indicate at an early stage that exposure has taken place and that a toxic response has been initiated. It is therefore expected that early biomarkers will play an increasing role as diagnostic tools for determining exposure to chemicals and the resulting effects. They may have predictive value that can assist in the prevention or minimising of risks. The aim of this study was to investigate the possibilities of using our results on biomarker responses of soil dwelling organisms to predict changes at higher organisational levels (which may have ecological implications). Our recent experimental results on the evaluation of various biomarkers in both the laboratory and the field are interpreted and placed in perspective within the broader framework of response biology. The aim was further to contribute to the development and application of biomarkers in regulatory risk assessment schemes of soils. This critical review of our own and recent literature on biomarkers in ecotoxicology leads to the conclusion that biomarkers can, under certain conditions, be useful tools in risk assessment. Clear relationships between contamination loads in soil organisms and certain biomarker responses were determined in woodlice, earthworms and terrestrial snails. Clear correlations were also established in field experiments between biomarker responses and changes at the population level. This indicated that, in spite of the fact that direct mechanistic links are still not clarified, biomarkers may have the potential to provide early indications of forthcoming changes at higher organisational levels. Ways are proposed in which biomarkers could be used in the future in risk assessment schemes of soils and future research directions are suggested.
ABA Brink: Pioneer of engineering geology in South Africa
Authors: Haarhoff J. , Korf L.
Published: August 2012

Anthony Berrange Antill Brink – beter bekend as ABA Brink aan die lesers van sy boeke, of net Tony vir sy groot aantal kennisse en vriende – was met sy geboorte in 1927 die derde en laaste kind van Rex Brink en Georgina Antill
Degradation of Y₂SiO₅ :Ce phosphor powders
Authors: Office Editorial
Published: August 2012

The degradation of the cathodoluminescence (CL) intensity of cerium-doped yttrium silicate (Y₂SiO₅:Ce) phosphor powders was investigated for possible application in low voltage field emission displays (FEDs).
Habitat preference, feeding distance and flight direction of cattle egrets (Bubulcus ibis) in the central Free State.
Authors: Butler Hennie , Kok Ordino
Published: August 2012

In the Free State, two thirds of all actively feeding cattle egrets (Bubulcus ibis) were observed in open grassland habitats. If the birds that fed in association with hosts are considered separately, the dominance of grassland, especially short grass, is even higher. By contrast, cattle egrets that fed independently of hosts showed a clear preference for tall grass and edges of water body. Marked differences in habitat use between cattle egrets that fed in the presence or absence of hosts even occurred on a temporal basis during the course of the day. More than three quarters (78,6%) of all cattle egrets observed in the vicinity of the Soetdoring Nature Reserve fed within a radius of 15 km of the breeding colony. Depending on the time of the year, significant changes occurred in the general flight direction from and to the colony. Positive correlations were obtained between the outward and return flights, but not between the general flight direction and prevailing wind direction.
The cardiovascular system, as understood in antiquity
Authors: Cilliers Louise , Retief François
Published: August 2012

Cardiovascular concepts in antiquity were primitive up to the early 5th century BC, when Greek philosopher-physicians like Empedocles and Diogenes divorced human physiology from its previous magico-religious base in order to find answers in the natural sciences. The heart was not initially seen as central to the cardiovascular system – blood (containing life-giving pneuma) moved through the body in blood vessels (phlebes) by way of a spontaneous “ebb and flow” motion. Their perceived anatomical vascular models were quite fanciful, but nevertheless accepted by the Hippocratic doctors, who, except for a single work, The heart (containing a useful description of the heart), added little of significance to the subject. Based on animal dissections, post-Hippocratic authors like Diocles and Praxagoras first distinguished between arteries and veins, confirmed that the heart had two main chambers (ventricles) and extended the theory that “innate heat” in the left ventricle produced pneuma which filled the arteries; only veins contained blood, produced in the right ventricle. Basing their theories on human dissections the Alexandrians, Herophilus and Erasistratus (3rd century BC) produced the first accurate descriptions of the heart and major components of the vascular system. Erasistratus even postulated minute (normally non-functional) peripheral arterio-venous anastomoses. The heart’s pump function was only partially understood – diastole was seen as the active phase of the cardiac cycle (sucking blood into the heart), and the pulse as inherent contraction of the arterial wall. After Herophilus and Erasistratus human dissection ceased, putting an end to further significant developments in unravelling the cardiovascular system. In the 2nd century AD, Celsus consolidated known knowledge, even adding minor contributions (e.g. a description of the coronary vessels) based on his own animal dissections. He mainly confirmed the Alexandrians’ findings and contemporary views on cardiac function, including inherent arterial pulsation, “ebb and flow” blood movement in veins, and the existence of pneuma. He claimed that arteries contained blood, not  pneuma. These views, as well an erroneous personal contribution (that there were minute pores in the heart’s interventricular septum), remained medical dogma throughout the Middle Ages up to the Renaissance.
Training people from disadvantaged groups in computer use: Is the backlog not too big to overcome?
Authors: Blignaut Pieter , Dednam Engela , Beelders Tanya
Published: August 2012

The digital divide is both a matter of having access to technology and being able to use it. There are several initiatives to roll out Information and Communication Technology (ICT) in public places in South Africa, but the question arises as to whether people will be able to use it effectively. Is the backlog with regard to general education and training not so insurmountable that people from disadvantaged communities are not educable for computer usage? This paper reports on the experiences and observations of instructors during a word processing training course for people from such communities. An interaction model that incorporates user and interface limitations with the difficulties experienced, serves as framework for the discussion. It became clear that most of the difficulties that attendees experienced were related to lack of technological experience, a limitation that can be eliminated through practice and perseverance. Enough practice might also result in an attenuation of the effects of some psychological limitations.
Quo vadis South African universities?
Authors: RE lutjeharms Johann
Published: August 2012

The Economist has recently identified some specific factors that explain why European universities are not competing adequately with their American counterparts. These factors are used here to evaluate South African government policy for universities. It is demonstrated that this current policy is directly contrary to what is now internationally considered best for universities in a knowledge economy.
A proposed regulatory framework for road and rail freight transport in South Africa
Authors: Pienaar Wessel
Published: August 2012

The increase in the number of freight vehicles on South Africa’s rural road network has received substantial attention. Insinuations persist that long-distance road freight haulage is of a somewhat unsavoury economic nature, and that strict economic re-regulation of the land freight transport is necessary. During the 1970s road transport replaced rail carriage as the dominant form of long-distance freight transport (excluding minerals and ore) in South Africa. On long hauls road freight carriers transport certain primary products of an organic nature (such as timber, fish and agricultural produce), some semi-finished goods, many finished goods and most consumer goods. Road freight carriers are continuously gaining market share on long-distance links where rail transport is the more cost efficient mode. The greater value added by road freight carriers in comparison with rail transport through service effectiveness is often more than the cost premium paid for utilising their service rather than making use of rail transport. Throughout history, governments have involved themselves in transport. A diverse range of arguments have been advanced for this involvement in transport, including the following:Control of excessive competition, co-ordination of transport, integration of transport with economic policy, maintenance of safety, security, and order, provision of costly infrastructure, provision of public goods, recovery of the true resource cost of transport inputs, regulation of harmful conduct and externalities, restraint of monopoly power, and social support. A set of nine instruments can be identified that governments apply to influence the performance of the freight transport industry: Legislation, direct supply, fiscal measures, monetary measures, moral appeal and persuasion, policies relating to strategic commodities, procurement policy, provision of information, and research and development. The best prospects for a sound development of land freight transport activity in South Africa will be offered within the framework of a free-functioning freight transport market.
Call for articles
Authors: Office Editorial
Published: August 2012

No Abstract
Leopards and landowners; Attitudes, conflict and incentives to increase leopard value on private properties
Authors: Office Editorial
Published: August 2012

Leopards are frequently found on private land where they come in conflict with game and livestock farmers. Economic incentives are increasingly seen as a means to mitigate conflict. This study showed that 56.6 % of landowners were positive towards leopards, but 52 % indicated that leopards had no value.
DIE SUID-AFRIKAANSE AKADEMIE VIR WETENSKAP EN KUNS 7de Jaarlikse Simposium vir Nagraadse Studente in die Natuurwetenskappe 2 November 2007, Tshwane Universiteit van Tegnologie
Authors: Office Editorial
Published: August 2012

The investigation of 1-hydroxyethylidene-1,1-diphosphonic acid and its complexes by Raman and NMR spectroscopy.
Lys van Keurders 2008
Authors: Office Editorial
Published: August 2012

Lys van Keurders 2008
Regstelling
Authors: Office Editorial
Published: August 2012

Regstelling
DIE SUID-AFRIKAANSE AKADEMIE VIR WETENSKAP EN KUNS
Authors: Office Editorial
Published: August 2012

No abstract.
Ambient NO2 concentration profiles in Flanders using passive sampling
Authors: Potgieter-Vermaak Sanja , Stranger Marianne , Verlinden Leen , Roekens Edward , Van Grieken Rene
Published: August 2012

In most parts of Europe NO2 emissions from excessive road traffic, concentrated by confined spaces and limited dispersion, are often higher than the ambient guideline values. As a pollutant,NO2 has a number of adverse effects on human health and the environment. The European Union sets guideline and threshold values for various pollutants, to protect humans and the environment, of which NO2 is one. Flanders adopted these values as most countries did, and the monitoring and evaluation of the levels against these guideline values are mostly done by VMM (the Flemish Environmental Company). The air quality Framework Directive (96/62/EG) was drafted on the27th of September 1996 and instituted on the 21st of November 1996. New guideline values forNO2 will come into effect in 2010 (1999/30/EG). The future hourly guideline value is 200 µg m-3which may not be exceeded more than 18 times in a calendar year. The average annual guideline value must not exceed 40 µg m-3.Currently various pollutants are continuously monitored by means of fixed monster monitors and analysers, where after data is extrapolated to give an overview of the dispersion. In the 2003annual report the future guideline value has been exceeded in 7 locations in Flanders. Moreover, in a separate study it was reported that in various locations with high traffic density and low dispersion, this value was exceeded, even though the dispersion model did not indicate it. Hence, to test these and other locations against the future guideline value a total of 19points, in 6 different cities and towns in Flanders, were chosen to monitor the NO2 profile over a1 year period. Passive sampling, averaged over periods of 2 weeks, was used and comparisons with the fixed monitors in some of these locations were possible. The future annual guideline value of 40 µg m-3 (2010) was exceeded in 11 of the 19 measured locations. When high traffic density was accompanied by low dispersion the value was at its highest and the results confirmed the relationship between high traffic density and high NO2concentrations. A good correlation between duplicate measurements and those compared to the fixed monitors ensured accurate and precise results. Ozone-rich periods were noted for the highNO2 values as expected, while seasonal effects were also noted. Backward trajectories indicated the significance of air masses originating from heavily polluted areas.
Elementary topology and universal computation
Authors: Potgieter Petrus
Published: August 2012

This paper attempts to define a general framework for computability on an arbitrary topological space X . The elements of X are taken as primitives in this approach—also for the coding of functions — and, except when X = N, the natural numbers are not used directly.
Global warming and climate change with reference to South Africa. Some perspectives
Authors: De Villiers Gawie , Viljoen Giel , Booysen Herman
Published: August 2012

According to the geological history of the earth, climate change is an integral part of environmental changes that occurred over time. Sufficient evidence is provided of recurrent wet and dry and cold and hot periods due to natural circumstances. Since the industrial revolution human activities increasingly contribute to air pollution by releasing huge volumes of carbon dioxide and other gasses into the atmosphere, so much so that it is generally accepted that increase in global warming the past decades is directly linked to human activities. Observable signs of human induced climate change include increasing average temperatures at many places, melting ice caps in polar areas, rising sea levels on a global scale and coastal disturbances and damages due to storm surges on coastal areas in various countries, also in South Africa. Consensus from a number of hydrological-meteorological circulation models show, for South Africa, a rise in average annual winter and summer temperatures of between 1.5 and 3.0 degrees Centigrade the following number of decades with a strong possibility of an increase in rainfall in the eastern parts and a decrease in rainfall in the western parts. Bigger floods and longer droughts should occur more frequently as well as severe sea onslaught activities along the eastern and south-eastern coastal areas. The net impact of the predictions on the community is negative. There is though other scientists who indicate that no concrete proof of climate change in South Africa exists; including changes with regard to river floods and droughts. According to more beneficial than detrimental. Despite the differences in opinion about the relative contribution of natural and human activities to the present global warming, changes in hydrological and characteristics of floods in several parts of South Africa in the immediate past, necessitate modifications to available models and approaches to flood damage management and control. Flood conditions need to be managed with applicable models. Modifications are furthermore essential as a result of meaningful demographic, social, physical and economic changes in the working and living environments of people and communities.
Cricket performance measures
Authors: Lemmer Hofﬁe
Published: August 2012

The purpose of this paper is to present a summary of batting and bowling performance measures that have been developed over a period of eight years. The measure of batting performance (BP) consists of three components. Firstly, an exponentially weighted average (EWA) is calculated in which recent scores have higher weights than scores further back in time in order to get a measure that adequately reﬂects the batsman’s present form. EWA is then adjusted up- or downwards depending on the batsman’s consistency and strike rate. This measure was subsequently generalized to BPW which includes weights for runs scored against speciﬁc countries in home or away matches separately. In the case of bowling, the ﬁrst challenge was to develop a single comprehensive measure of bowling performance, the combined bowling rate (CBR) for limited overs matches and the dynamic bowling rate (DBR) for unlimited overs matches. Hence, by alsotaking bowling consistency into account, the current bowling performance measure (CBP) wasdeveloped. This measure was also extended to include weights for wickets taken and runs concededagainst each international team in home or away matches. These measures contain parametersthat were based on players’ scores up to the speciﬁc date of calculation. Before using the latestavailable data for the present presentation, it is logical to update these parameters. This hasbeen done in the present study. If a player performs well at local level, it is important to be ableto compare his performance with those of players already in the national team. Weights havebeen determined for runs scored by batsmen and also for runs conceded and wickets taken bybowlers in local matches, whereby the performances of players can be compared irrespective ofthe proportion of international matches played by each player. After having used the measures onvarious occasions the need arose to revise some of them slightly. The updated measures are thenused to give rankings of South African batsmen and bowlers in First Class and List A matchesalike. Methods have also been developed to compare the batting and bowling performances ofplayers after a short series of matches. It was shown that the traditional average could haveunrealistic values in the case of a batsman who had a large percentage of not out scores in ashort series. Alternative measures have been developed and shown to give much more realisticvalues. In the case of bowling it is important not only to count the number of wickets a bowlerhas taken, but to distinguish between the wickets of top and middle order batsmen on the onehand and lower order batsmen on the other. A system has been established whereby weights areattached to the wickets according to the batting position of the batsman. Instead of just countingthe number of wickets taken, the sum of the weights of the wickets taken by the bowler is usedin the calculation of CBR* or DBR*. Finally, the latest form of the game, Twenty20 cricket, isalso discussed.
Scheduling spouse - avoiding mixed doubles round - robin tennis tournaments
Authors: Burger A. P. , Van Vuuren J. H.
Published: August 2012

The problem of scheduling a spouse-avoiding mixed doubles round-robin tennis tournament (SMDRTT) of order involves finding a playing schedule for married couples in such a way that no player teams up with his/her spouse, no player opposes his/her spouse, each player opposes every other player of the same sex exactly once, each player teams up with every player of the opposite sex (except his/her spouse) exactly once, and each player opposes every player of the opposite sex (except his/her spouse) exactly once.
The steric and electronic effects of metal-containing substituents on Fischer carbene metal clusters
Authors: Office Editorial
Published: August 2012

Novel Group VI transition metal Fischer carbene complexes containing three different transition metal substituents, all in electronic contact with the carbene carbon atom, were synthesised.