Browsing by Author "Fourie, Paul"

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    A cost-effective protocol for molecular detection of fungal pathogens in soil
    (Academy of Science for South Africa, 2005) Damm, Ulrike; Fourie, Paul
    DNA EXTRACTION FROM FUNGI IN SOIL often fails because of humic substances that are co-extracted with the DNA and subsequently inhibit PCR analyses. Moreover, it is difficult to release the fungal DNA because of the diverse fungal structures residing in soil. Since available DNA extraction protocols and commercial kits are expensive or time-consuming, we have devised a superior method by testing different components of these procedures on grapevine nursery soils. The best DNA yield and sensitivity were obtained by a short and easy extraction method with sodium dodecyl sulphate buffer using the FastPrep homogenizer. An easy-to-prepare spin column with polyvinylpoly-pyrrolidone was developed to remove PCR inhibitors. In the presence of bovine serum albumin, PCR reactions were possible without further dilutions of the DNA. Our method was more sensitive for detecting Phaeomoniella chlamydospora, the organism responsible for Petri grapevine decline, and Cylindrocarpon black-foot pathogens in grapevine nursery soils than the FastDNA SPIN Kit for Soil and enabled us to perform 25 extractions for the price of one with the kit. This is the first report of molecular detection of Cylindrocarpon macrodidymum from soil and the first account of Pa. chlamydospora from soils in South Africa.
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    The impact of merger-related employee status on engagement, burnout and counterproductive work behaviour of employees of a South African Commercial Bank
    (Stellenbosch : Stellenbosch University, 2013-03) Fourie, Paul; Malan, Dirk Johannes; Stellenbosch University. Faculty of Economic and Management Sciences. Dept. of Industrial Psychology.
    ENGLISH ABSTRACT: The banking industry today is seen as a demanding world of work where employees are constantly exposed to high demands and this may have an influence on their work engagement levels and their organisational commitment. It seems that in this industry, employee turnover and absenteeism levels are high, and some employees seem to be de-motivated in their work. The impact of this changing world is most evident in changes in the employment relationship that exist between employer and employee. Employees are expected to give more in terms of time, effort, skills and flexibility, whereas there is a strong perception that employees receive less in terms of career opportunities, lifetime employment and job security. It is in view of the above work complexities that employee engagement has become a focus area, and in particular, to understand the mediating effects of certain psychological conditions in relation to work engagement. Should either employment party not fulfil its contractual terms in any way, the psychological contract will be breached or violated and the employee might attempt to balance the situation by reducing his or her job efforts and making use of various counterproductive work behaviours. Transformation or change of the working circumstances, such as during or after mergers, seem to present a serious challenge to the employment relationship and the prevailing levels of job satisfaction, organisational commitment and productivity. The research question for this study was: “To investigate whether differential exposure of employees of a retail bank to change-related stressors is associated with different configurations of perceived job demands and job resources, affective states, psychological contract, job engagement, burnout and counterproductive work behaviour, and to study the relationships between these variables with the view to understanding the development of the job engagement, burnout and performance-related behaviours of these employees”. This study utilised a quantitative descriptive research design to analyse the data using statistical procedures. All the data was statistical in nature. The sample (n = 300) comprised of employees of three main levels on the organigram such as, team leaders, team managers and employees, from the Regional Head Office in Pretoria. The primary research tool utilised to conduct the study was a self-compiled questionnaire. This was hand delivered and collected from all respondents. The six questionnaires constituting the composite questionnaire were: the Maslach Burnout Inventory (MBI-GS), Counterproductive workbehaviour Inventory (CWB), Utrecht Work Engagement Scale (UWES), the Job Characteristics Inventory (JCI), Psychological Contract Inventory (PCI) and the Warwick-Edinburgh Mental Well-being Scale (WEMWBS). The descriptive statistics reflected a majority of participants had been working for 1 to 4 years (34%) and 5 to 9 years (33%). The largest percentages of participants (74%) were team members while other participants were defined as team leaders (22%) and team managers (4%). The majority of these participants (59%) were also appointed prior to the merger while the median was calculated at 3 years for the amount of years the participants have remained in their current job band (salary structure). A very high percentage of participants (82%) did not manage people directly nor indirectly (83%). It was found that an inter-correlation existed between the demographic variables and the psychological constructs, confirming that the number of years employed was associated with a lower likelihood of psychological withdrawal. While the years of employment in the same position related positively with absorption, and negatively with perceived job resources, the level of abuse experienced, showed a positive association with the degree of psychological contract adherence by the employee and a negative correlation with the extent of perceived contract violation. Evidence was also found for the moderating effect of work engagement in the relationship between well-being and work engagement and between work engagement and some of the counterproductive work behaviour dimensions. Evidence also revealed that mental well-being was experienced some of the time and counterproductive work behaviour almost never. The higher burnout scores, coupled with the simultaneous higher level of work engagement could possibly be viewed as an exploitable factor. The limitations of the current study and recommendations for organisations are discussed. This study highlights the fact that virtually all the comparisons between the pre-merger appointees and the post-merger appointees were insignificant. Burnout was however much more evident with the post-merger group. Employee or employer obligations towards the respondents were also viewed as insignificant, irrespective of the differences in psychological contract each employee experiences.
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    Modeling the effect of temperature and wetness on Guignardia pseudothecium maturation and ascospore release in citrus orchards
    (American Phytopathological Society, 2013) Fourie, Paul; Schutte, Tian; Serfontein, Suzel; Swart, Fanus
    Ascospores are the most important inoculum source of citrus black spot (CBS), caused by Guignardia citricarpa, but pseudothecium maturation and ascospore release are inadequately studied. Guignardia ascospore trapping and concomitant weather data were obtained for three localities over three seasons (July to March 2006 to 2009) in the Limpopo province of South Africa. Degree-days accumulated until first seasonal ascospore discharge (>10°C with 1 July as biofix) (DDtemp), and DDtemp accumulated on rainy (rainfall >0.1 mm) (DDrain) and moist days (vapor pressure deficit <5 hPa) (DDvpd) were used in two Gompertz models to predict onset of ascospore release: a temperature model [Event = exp(–exp(–(–2.725 + 0.004 × DDtemp)))] and a temperature/moisture model [Event = exp(–exp(– (–3.238 + 0.008 × DDvpd + 0.004 × DDtemp – 0.009 × DDrain)))] (R2 = 0.608 and 0.658, respectively). Both models predicted a delay in pseudothecium maturation in climates with colder winters and springs. A Gompertz equation was also used to predict the proportion of Guignardia ascospores trapped (PAT) per season from DDtemp data accumulated on wet or moist days (DDwet2) from the first seasonal ascospore discharge [PAT = exp(–4.096 × exp(–0.005 × DDwet2); R2 = 0.908]. The PAT model predicted lag phases and 7-day peaks in ascospore release patterns with reasonable accuracy. These models can be used to predict the onset and dynamics of ascospore release in climatically diverse regions.
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    Pulse power device characterization for amplifier design
    (Stellenbosch : University of Stellenbosch, 2004-12) Fourie, Paul; Van Niekerk, C.; University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: Bi-polar Si transistors optimized for pulse conditions is still the most popular choice as amplification element in the final stages of solid-state radar amplifiers in L and S band. With the radar market being small, the design data for these devices is normally fairly limited and it is up to the designers to thoroughly characterize them for their designs. This is normally done through loadpull experiments. Professional automated load-pull equipment is very expensive especially at the higher power levels. In spite of being automated and under computer control, load-pull exercises still is very time consuming and as such expensive. For small companies that only occasionally need to design such amplifiers it is not economically viable to acquire such equipment and different strategies have to be found to stay competitive. This report investigates such a strategy and its implementation. A procedure to quickly and accurately characterize such devices was developed and two amplifiers were designed and build with this procedure and compared to their traditional counterparts for verification. The results were very promising and with a bit more work, the technique can likely be used to characterize these devices for design work outside of the parameters designated by the manufacturers.