The absence of diffusion in the South African short rate

In the field of Financial Mathematics, stochastic differential equations are used to describe the dynamics of interest rates. An example is a model for the short rate, which is a mathematically defined rate not directly observable in any market. However, observable rates such as short dated Treasury rates or the Johannesburg Interbank Agreement Rate (JIBAR) can be used as proxies for the short rate.The short rate dynamics are traditionally modelled by one-factor diffusion processes. These type of models remain popular due to the analytical tractability of the pricing formulae of interest rate derivatives under these models. To capture the leptokurtic nature of interest rate returns in the South African market, two types of models can be used: a pure jump model or a jump diffusion model. In this paper we investigate whether jumps are present and whether a diffusion component is evident. Our initial investigation showed that jumps were present in the South African market, and that no diffusion component was evident at low interest rate levels. This result was found using a Monte Carlo method to test for jumps. We therefore conclude that a pure jump process is an appropriate model for the South African short rate

Die gesinsdinamika van pastoriegesinne in die drie Afrikaanse kerke

The divorce rate among white South Africans is disturbing. There are indications of a growing divorce rate also among families of ministers of religion. Little scientific research seems to be available on the marital and family life of ministers, especially in the RSA. The aim of the research on which this article is based was to determine whether significant differences occur between the marital and family dynamics of ministers' families and the families of parishioners. Thirty clerical couples and some of their children (N=96) and thirty parish couples and some of their children (N=95) were involved in the research. Six measuring instruments were applied in evaluating the families. The results seem to indicate that the clerical couples experience their marital dynamics significantly better than the other married couples on 12 o f the 19 dimensions which were evaluated. With regard to family functioning the ministers’ families performed significantly better than the parish fa milies on six of the 14 dimensions. There are indications, however, that the clerical couples represented their marital and family functioning in a more positive light than was the case in reality. Therefore no really valid interpretations can be made from the results

An evaluation of the efficiency of laser scanning technology in the quantitative analysis of corrosion

Abstract: It is estimated that corrosion causes around R260 Billion of damage to infrastructure and equipment in the South African industry annually. Corrosion evaluation and protection in the marine environment is well established. In the mining industry the field of corrosion evaluation is not as well established as it could be. The evaluation and measurement of corrosion rates and physical deterioration of structures through electrochemical measurement, visual inspection and non‐destructive test method measuring techniques are well established. The use of sonar (ultrasonic) and laser scanning has been investigated. Laser scanning technology has improved exponentially over the past years and terrestrial and hand‐held units are now smaller, more manageable and affordable to the surveyor. Conventional laser scanners are able to measure to an accuracy of millimeters and generate a point cloud of 1million points per second in some cases. Latest developments in laser scanning include multi‐spectral analysis and Red‐Green‐Blue (RGB) intensity values for each point. Point clouds of data can now be imported into a CAD package and compared to design specifications. In the case where “as‐built” specifications differ for the initial design, laser scanning allows the engineer the opportunity to compare and quantify in minute detail the differences between the final structure and the original design..

Calibration artefacts in radio interferometry. I. Ghost sources in WSRT data

This work investigates a particular class of artefacts, or ghost sources, in radio interferometric images. Earlier observations with (and simulations of) the Westerbork Synthesis Radio Telescope (WSRT) suggested that these were due to calibration with incomplete sky models. A theoretical framework is derived that validates this suggestion, and provides predictions of ghost formation in a two-source scenario. The predictions are found to accurately match the result of simulations, and qualitatively reproduce the ghosts previously seen in observational data. The theory also provides explanations for many previously puzzling features of these artefacts (regular geometry, PSF-like sidelobes, seeming independence on model flux), and shows that the observed phenomenon of flux suppression affecting unmodelled sources is due to the same mechanism. We demonstrate that this ghost formation mechanism is a fundamental feature of calibration, and exhibits a particularly strong and localized signature due to array redundancy. To some extent this mechanism will affect all observations (including those with non-redundant arrays), though in most cases the ghosts remain hidden below the noise or masked by other instrumental artefacts. The implications of such errors on future deep observations are discussed.Comment: 19 pages, 15 figures, submitted to MNRA

Multidisciplinary Training to Undergraduate Students in the Faculty of Health Sciences: Hypertension as a Case Study

Background: Healthcare students should be aware of the specific skills, knowledge and management options of other disciplines in order to achieve an effective and cohesive working relationship. Aim: The aim of this study was to expose healthcare students at the University of the Free State to one another\'s domains, as related to hypertension management, during a formal didactic lecture attended by medical, physiotherapy and dietetic students, and to determine whether they could apply in practice the theoretical knowledge regarding blood pressure measurement and exercise, obtained during a multidisciplinary session. The perceptions of students regarding multidisciplinary sessions were also to be obtained. Method: Students received a formal lecture on hypertension from a medical doctor, a dietitian, a physiotherapist and an occupational therapist and they then worked in multidisciplinary groups to demonstrate the physiological effect of exercise on blood pressure and pulse rate. Students had to report their findings and perceptions of the session by completing data forms. Results: A total of 125 medical, physiotherapy and human nutrition students participated in the session. The students were able to demonstrate the influence of exercise on blood pressure and pulse measurements. They reported that they enjoyed the multidisciplinary session and gained information on the scope of practice of the domains of the other disciplines. Negative feedback was received on the size of the groups and lack of equipment. Conclusion: The students could apply theoretical knowledge in practice and all gave positive feedback. The sessions will continue in the current format but attention will be given to smaller groups and the availability of more equipment. South African Journal of Family Practice Vol. 50 (4) 2008: pp. 70a-70

Major depressive disorder

This treatment guideline draws on several international guidelines: (i) Practice Guidelines of the American Psychiatric Association (APA) for the Treatment of Patients with Major Depressive Disorder, Second Edition; (ii) Clinical Guidelines for the Treatment of Depressive Disorders by the Canadian Psychiatric Association and the Canadian Network for Mood and Anxiety Treatments (CANMAT); (iii) National Institute for Clinical Excellence (NICE) guidelines; (iv) Royal Australian and New Zealand College of Psychiatrists Clinical Practice Guidelines Team for Depression (RANZCAP); (v) Texas Medication Algorithm Project (TMAP) Guidelines; (vi) World Federation of Societies of Biological Psychiatry (WFSBP) Treatment Guideline for Unipolar Depressive Disorder; and (vii) British Association for Psychopharmacology Guidelines.http://www.sajp.org.za/index.php/sajpam2013ay201

Integrating Geographic Information into the Analysis of the Genetic Distribution of South African Vervet Monkeys

This project uses the program Geneland to reanalyze McAuliffe’s (2008) thesis data on genetic variability in three South African vervet monkey populations (Polokwane, Oribi and Blyde). Using information on the geographic location and genetic variability of these populations, the spatially explicit Geneland program shows that the three populations are weakly differentiated. These findings oppose the results of previous genetic studies of South African vervet monkeys as well as the results obtained by McAuliffe with the spatially implicit Structure program, which found that the 34 individuals all come from one population. Based on this historic data and the fact that other studies have found the same number of subpopulations with both Structure and Geneland, I conclude that Polokwane, Oribi and Blyde are slightly differentiated, though not distinct enough to be considered separate populations (Latch et al. 2008). These results need to be supported by an analysis of the entire sample of South African vervet monkey genetic data from up to 200 animals prior to suggesting policy changes regarding genetic structuring in South African vervet monkeys

HUMAN RESOURCE MANAGEMENT PRACTICES IN SOUTH AFRICA

This report provides the results of a survey of South African human resource management (HRM) practices in private and public organisations. The survey is part of a longitudinal, comparative study of human resource policies and practices, involving 35 countries worldwide. This is the third survey conducted in South Africa during 2014/2015, the previous two surveys were conducted in 1999/2000, and 2009/2010 respectively. This report provides an overview of the key findings of the South African survey. The basis of the survey was a questionnaire completed by human resource (HR) managers on behalf of their organisations. The research reflects policies current in 2014. This report affords organisations in South Africa an opportunity to benchmark themselves against other South African organisations, and to identify trends in HRM practices.Human Resource Managemen

Redundant interferometric calibration as a complex optimization problem

Observations of the redshifted 21-cm line from the epoch of reionization have recently motivated the construction of low frequency radio arrays with highly redundant configurations. These configurations provide an alternative calibration strategy - "redundant calibration" - and boosts sensitivity on specific spatial scales. In this paper, we formulate calibration of redundant interferometric arrays as a complex optimization problem. We solve this optimization problem via the Levenberg-Marquardt algorithm. This calibration approach is more robust to initial conditions than current algorithms and, by leveraging an approximate matrix inversion, allows for further optimization and an efficient implementation ("redundant StEfCal"). We also investigated using the preconditioned conjugate gradient method as an alternative to the approximate matrix inverse, but found that its computational performance is not competitive with respect to "redundant StEfCal". The efficient implementation of this new algorithm is made publicly available.Comment: 11 pages, 7 figures, MNRAS accepte

Content validation of Mental Health Literacy Scale (MHLS) for primary health care workers in South Africa and Zambia a heterogeneous expert panel method

Background: The lack of public knowledge and the burden caused by mental-health issues' effect on developing and implementing adequate mental-health care for young and adolescent in low- and middle-income countries (LMIC). Primary health care could be the key in facing the challenge, but it suffers from insufficient resources and poor mental health literacy. This study's aim was to adapt the content validity of the Mental Health Literacy Scale (MHLS) developed by O'Connor & Casey (2015) with researchers and primary health-care workers in low- and middle-income contexts in South Africa (SA) and in Zambia. Objectives: The study population comprised two expert panels (N = 21); Clinical Experts (CE) (n = 10) from Lusaka, Zambia and Professional Research Experts (PE) (n = 11) from the MEGA project management team were recruited to the study. Methods: MHLS was validated in a South African and a Zambian context using a heterogeneous expert-panel method. Participants were asked to rate the 35 MHLS items on a 4-point scale with 1 as not relevant and 4 as very relevant After the rating, all 35 MHLS items were carefully discussed by the expert panel and evaluated according their relevance. The data were analyzed using an item-level content validity index (I-CVI) and narrative and thematic analyses. Results: All 35 items ranked by the PREs met the cutoff criteria (>= 0.8), and ten (n = 10) items were seen as relevant by CE when calculating I-CVIs. Based on the results of ratings and discussion, a group of sixteen (n = 16) of all items (n = 35) were retained as original without reviewing. A total of nineteen (n = 19) items were reviewed. Conclusion: This study found the MHLS to have sufficient validity in LMICs' context but also recognized a gap between professional researchers' and clinical workers' knowledge and attitudes related to mental health.</div