Opleiding in elektroniese ingenieurswese - deurbraak of dwaling?

After briefly tracing the evolution of engineering activity in South Africa, the author turns his attention to the scope of electronic engineering activity in the world in general, and in South Africa in particular, showing that there is a surprisingly high annual investment in new electronic equipment locally, practically all of which is imported from overseas. Comparing the electronics industry to the basic steel and liquid fuel industries, it is shown that the rapid growth of this industry is essential for South Africa's survival. The reasons why the introduction of television in South Africa has failed to stimulate a local manufacturing industry, are discussed. The need for properly trained man-power and the determining role of electronics engineering in the industrial and military spheres in South Africa, are highlighted.p. 15-17 : Publikasies van die Universiteit van Pretoria (Nuwe Reeks)http://explore.up.ac.za/record=b179587

Modeling the TDEM response for a lateral change in conductivity

The solution of the transient response of a layered earth excited by a vertical magnetic dipole is well known and used. Expansion of the solution for a 2D or 3D earth, where the conductivity changes in not just the z-direction, is extremely difficult and has only been done by way of numerical schemes, which are laborious even on powerful computers. In this study a current filament is used to generate magnetic fields and its derivative. This current filament diffuses like a smoke ring, downwards and outwards through the earth in time, and is defined by the following parameters: a current amplitude, a horizontal expansion velocity and a vertical or downward velocity. The influence of the conductivity and layer thickness are investigated and it is found that the parameters of the moving current filament is an integrated function of the total resistivity distribution of the layered earth model. For this study a current ring in different environments is used and the results compared. This process indicates that the current filament can be used to model differences in apparent conductivity without considering the thicknesses of layers. The parameters of the current filament are changed one at a time, keeping the other constant, to investigate the influences of each. This technique is then applied to a 2D case, where transient sounding data is generated in the centre of the transmitter loop. The 2D model consists of a vertical geo-electrical boundary which is infinite in strike. The resistivity ratio between the two regions is low and it is assumed that only a primary field is present, as is the case with a layered earth. A qualitative approach is used to determine if and when there are significant changes in the measured temporal field. The apparent resistivity is calculated using the derivative of the magnetic field as defined m Kaufman and Keller, 1983. This has also been applied to the magnetic field and it has been found that there is no difference for this qualitative model between the two approaches. It has been found that the distortion of the current filament is dependent on the locality of the transmitter loop, with a larger distortion when the transmitter loop is located on the more conductive side of the discontinuity. Lastly, this study proven has the feasibility of using the concept of a moving current filament to formulate forward models for 2D and 3D models, if the proper velocity functions are known.Dissertation (MSc)--University of Pretoria, 1997.GeologyMScUnrestricte

Genetic variability, stability and heritability for quality and yield characteristics in provitamin A cassava varieties

Open Access Article; Published online: 25 Jan 2020Cassava is widely consumed in many areas of Africa, including Ghana, and is a major part of most household diets. These areas are characterized by rampant malnutrition, because the tuberous roots are low in nutritional value. Provitamin A biofortified cassava varieties have been developed by the International Institute for Tropical Agriculture, but adoption of these varieties in Ghana will largely depend on their agronomic performance, including fresh root yield, dry matter content, resistance to major pests and diseases, mealiness, starch content and the stability of these traits. Eight provitamin A varieties with two white checks were planted in three environments for two seasons to determine stability and variability among the varieties for important traits. There were significant variations in performance between varieties and between environments for cassava mosaic disease, root number, fresh root yield and starch content. High broad-sense heritability and genetic advance were observed in all traits, except for storage root number, and could be exploited through improvement programs. This study identified the best performing enhanced provitamin A varieties for traits that are key drivers of variety adoption in Ghana. In view of this, some varieties can be recommended for varietal release after on-farm testing. The study also showed the possibility of tapping heterosis after careful selection of parents

Seedling Shoot and Root Growth Responses among Soybean (Glycine max) Genotypes to Drought Stress

Drought stress is a major limiting factor in soybean production in South Africa. The development of soybean varieties with enhanced tolerance to soil waterlimited induced stress (WLIS) is one sustainable way to deal with drought. Root traits have shown strong potential for improvement of drought tolerance through breeding. The objectives of this study were to evaluate seedling shoot- and root growth responses under WLIS in order to study root morphology as a mechanism to cope with drought stress and to determine if there were genotypic differences in shoot- and root morphology between drought tolerant and -sensitive soybean genotypes. Seedlings of three drought tolerant and one sensitive genotype were subjected to soil WLIS in deep-root-pots for 21 days. Results suggested significant genotypic differences for shoot length, number of leaves, tap root length and root-to-shoot length ratio. Soybean tolerant genotypes were associated with moderate shoot biomass, deep rooting abilities and maintained a large root-to-shoot ratio under WLIS conditions. In contrast, the sensitive genotype was associated with a reduced root-to-shoot ratio and shallower root system. Soybean genotypes showed varying seedling root growth responses to soil WLIS, while shoot biomass characteristics were similar

Promoting hospital-based smoking cessation services at major Swiss hospitals: a before and after study.

Whether a 1-year nationwide, government supported programme is effective in significantly increasing the number of smoking cessation clinics at major Swiss hospitals as well as providing basic training for the staff running them. We conducted a baseline evaluation of hospital services for smoking cessation, hypertension, and obesity by web search and telephone contact followed by personal visits between October 2005 and January 2006 of 44 major public hospitals in the 26 cantons of Switzerland; we compared the number of active smoking cessation services and trained personnel between baseline to 1 year after starting the programme including a training workshop for doctors and nurses from all hospitals as well as two further follow-up visits. At base line 9 (21%) hospitals had active smoking cessation services, whereas 43 (98%) and 42 (96%) offered medical services for hypertension and obesity respectively. Hospital directors and heads of Internal Medicine of 43 hospitals were interested in offering some form of help to smokers provided they received outside support, primarily funding to get started or to continue. At two identical workshops, 100 health professionals (27 in Lausanne, 73 in Zurich) were trained for one day. After the programme, 22 (50%) hospitals had an active smoking cessation service staffed with at least 1 trained doctor and 1 nurse. A one-year, government-supported national intervention resulted in a substantial increase in the number of hospitals allocating trained staff and offering smoking cessation services to smokers. Compared to the offer for hypertension and obesity this offer is still insufficient

‘Deliberate Preparation’ as an evidence-based focus for primary physical education

There is substantial scientific research suggesting the physical and psychological health benefits of a physically active lifestyle. Consequently, governments worldwide prioritize policies, finances, and resources in healthcare, education, and sports sectors to increase mass participation in physical activity. However, practices in physical activity promotion are often not underpinned by evidence-based standardization that is requisite in other domains of epidemiology. The aim of this article is to examine critically the available scientific research on promoting life-long physical activity participation and to propose an evidence-based model for implementation in school physical education. Reasons are discussed as to why programs that integrate physical, psychological, and behavioral skills have been long acknowledged in physical education and physical activity domains but remain lacking in empirical validation. Finally, future directions are suggested that are required to examine the application of this approach to practice in primary-level physical education

eModeration: Towards a User Experience Evaluation Framework

eModeration (or online moderation) can improve the user experience of the examination process while lowering the risk of losing scripts or delaying the moderation process. Despite these benefits to optimising examination procedures, the application of online moderation is limited. There could be various reasons for the lack of adopting eModeration including the technical, organisational and human factors. The focus of this study is on the human factors involved in eModeration and the research is guided by the following question: What are the most important user experience constructs for valuating an electronic moderation (eModeration) system within the context of Higher Education Institutions in South Africa? This research uses a design science methodology, which comprises the development and testing of a user experience framework. In this paper, we will only report on the identification of the constructs for the user experience framework. The data generation methods will include interviews with deans from the different faculties and a survey with moderators and deans. The research was conducted at Midrand Graduate Institute, a Private Higher Education institution in South Africa. The contribution of the paper is to identify the most important user experience constructs for evaluating an eModeration system and also to provide some insights on the user experience of the two different user groups. The enriched understanding of eModerators’ and deans’ user experience of eModeration contributes to the understanding of the human factors that influence the adoption of innovative assessment practices.College of Engineering, Science and Technolog

Risk factors for progression of chronic kidney disease : an investigation in prepubertal children

AIM : Previous studies on progression of chronic kidney disease (CKD) in children have included older post-pubertal subjects. This study attempted to evaluate risk factors for progression of CKD in pre-pubertal children. METHODS : An observational study of children aged 2–10 years with an eGFR within the limits of >30 and <75 mL/min/1.73 m2 was performed. Presenting clinical and biochemical risk factors, as well as diagnosis, were analysed for their association with progression to kidney failure, time to kidney failure and for the rate of decline of kidney function. RESULTS : One hundred and twenty-five children were studied of whom 42 (34%) had progressed to CKD stage 5 during the median period of follow up of 3.1 (IQR = 1.8–6) years. Hypertension, anaemia and acidosis at entry were associated with progression but they did not predict reaching the end point. Only glomerular disease, proteinuria and stage 4 kidney disease were independent predictors of kidney failure and the time to kidney failure. The rate of kidney function decline was greater in patients with glomerular than non-glomerular disease. CONCLUSION : Common modifiable risk factors, when present at initial evaluation, were not independently associated with CKD progression to kidney failure in prepubertal children. Only non-modifiable risk factors and proteinuria predicted eventual stage 5 disease. The physiological changes of puberty may be the major precipitator of kidney failure during adolescence.http://wileyonlinelibrary.com/journal/nephj2023Paediatrics and Child HealthSurger

Physical activity levels in urban-based South African learners: A cross-sectional study of 7 348 participants

Background. Establishing profiles of physical activity (PA) is critical in tackling the chronic diseases associated with lack of PA and avoiding healthcare costs.Objective. To investigate PA levels in urban-based South African (SA) primary school learners.Methods. The Physical Activity Questionnaire for Older Children was completed by 7 348 learners (3 867 males and 3 481 females) aged 8 - 14 years, of whom 49% were white, 39% black and 12% from other ethnic groups. Differences in PA levels by ethnic origin and province were determined using an analysis of covariance after adjusting for gender (p&lt;0.05). Bonferroni corrections controlled for multiple comparisons. A fitted regression model examined age-related differences in PA adjusting for province.Results. Of SA learners aged 8 - 14 years, 57% (n=4 224) engaged in moderate levels of PA. Thirty-one percent (n=2 247) did not meet internationally recommended amounts of moderate to vigorous physical activity. Overall, males reported higher PA levels than females (p&lt;0.0001). PA levels declined with age from 11 to 14 years by 14% and 20% in males and females, respectively. Black learners had higher PA levels than white learners (p=0.0039). There were also significant differences in PA levels between the provinces (p&lt;0.0001).Conclusion. This study provides evidence of differences in PA levels between gender, age and ethnic groups, and between provinces. A targeted approach to increase PA in high-risk populations in SA is warranted. Increased PA will help reduce the risk of chronic diseases and will contribute to the health of SA’s population and the growth of the country’s economy.