The long-term effect of radio sources on the ICM

We have performed 3D hydrodynamical simulations of FR-II radio sources in beta-profile cooling-flow clusters. The effects of cooling of the cluster gas were incorporated into a modified version of the ZEUS-MP code. The simulations followed not only the active phase of the radio source, but also the long term behaviour for up to 2 Gyr after the jets of the radio source were switched off. We find as expected that the radio source has a significant effect on the cooling flow while it is active, however we also find that the effects of the radio source on the cluster are long-lived. A buoyancy driven convective flow is established as the remnants of the radio source rise through the cluster dragging material from the cluster core. Although the central Mpc of the cluster reverts to having a cooling flow, this asymmetric convective flow is able to remove the cool gas accumulating at the cluster core and indeed there is a net outflow persisting for timescales of about an order of magnitude longer than the time for which the source is active or longer. The convective flow may also provide a mechanism to enhance the metallicity of the cluster gas at large cluster radii.Comment: 7 pages, 13 figures; minor addition

A phenomenological study into the experience of their sexuality by males with spinal cord injury: research

On reviewing the literature on spinal cord injury (SCI) and sexuality in males, there was found to be a plethora of research in physical domains. Sadly, the psychological aspect of sexuality for men who experience SCI has been largely neglected. For this reason a phenomenological study was conducted to understand the experience of sexuality in its totality for the male who experiences SCI. Four males with SCI were included in the study. Central themes that emerged from the transcribed interviews included the establishment of an existential baseline, diminished independence and perceptions of masculinity post-injury. Participants also divulged needs pertaining to their (potential) relationships. Lastly, religion and certain coping mechanisms were found to either facilitate or hinder sexuality post-trauma depending on their rigidity and effectiveness respectively. Die studie van literatuur oor rugmurgbesering (RMB) en seksualiteit by mans, het 'n magdom navorsing oor die fisieke aspekte opgelewer. Ongelukkig is die sielkundige aspekte rondom seksualiteit by mans met RMB grootliks afgeskeep. Derhalwe is 'n fenomenologiese studie onderneem ten einde die man met RMB se ervaring van seksualiteit in sy geheel te ondersoek. Onderhoude is met vier mans wat RMB het gevoer. Sentrale temas wat uit die onderhoude voortvloei, sluit die vasstel van 'n eksistensi?le basislyn in, asook verminderde onafhanklikheid en veranderde beskouings oor manlikheid na die besering. Deelnemers het ook hulle behoeftes met betrekking tot hulle (potensi?le) verhoudings aangedui. Laastens is daar gevind dat godsdiens en sekere hanteringsmeganismes 'n positiewe of negatiewe impak kan h? op seksualiteit, afhangend van die rigiditeit en effektiwiteit daarvan. Keywords: Spinal cord injury, Sexuality, Males, Phenomenology, Experience (Health SA Gesondheid: interdisciplinary research journal: 2003 8(4): 3-11

The Place And Role Of Em-learning In Multi-mode Delivery Of Educator Training In South Africa

In any country in the world, the business and responsibility of, as well as the challenge to the education fraternity are to provide quality education to all. Therefore, quality teaching and learning should be provided to assist all learners to acquire the required competencies (knowledge, skills and attitudes) at the highest possible level in order to fulfil their respective and diverse roles in life (Steyn, Steyn, De Waal and Wolhuter, 2002: 34). The point of departure should be to provide quality education in such a way that it is accessible and affordable to all. The quality of education is to a large extent determined by the quality of information transfer and the quality and quantity of support that the learners receive to master the outcomes of their studies. The developments in the field of Information and Communication Technology (ICT) provide a real opportunity to improve the quality of information transfer and teaching support that learners can obtain. However, the real challenge for education in the developing world, and even in the developed world, is the level of accessibility, affordability and complexities of ICT (Dreyer, 2005: 4). The result of the ability to provide assessable ICT in developing countries is the ever-increasing digital gap that deeply influences the quality of education of less affluent people and the difference in quality of education between developed and developing countries. At the North-West University, Faculty of Education Sciences, the decision was made to provide enriched teaching and learning to a particular group of teachers via an off-campus blended teaching and learning strategy. Within the limitations of affordability and access, the decision was made to use the multi-mode teaching strategy (including some types of modern ICT) to support the students and to enhance the support that the learners obtain. The aim of this article is to report on the reasons, development and implementation of the project as well as initial results. Attention will be given to the nature and contents of the ADP-programme, the theoretical framework that was used to develop the strategy and the nature and content of the multi-mode teaching strategy that was employed. The method of research that was used to develop the teaching and learning strategy particularly applicable to this programme was that of a process of iterative and systematic critical reasoning. Based on the critical reasoning, it was through an combined (and not necessarily initially decided upon) application of several (applicable) scientific methods and processes, such as observation, analysis and synthesis, induction and deduction that the strategy was developed (Stoker, 1961: 62-90; Mouton and Marais, 1989: 102; Mouton, 1996; 77-78; Harden and Thomas, 2005: 258; Bensley, 1998: 3; Ennis, 1987: 9).Faculty of Education Sciences North-West Universit

Characterization and Oxidative Addition Reactions of Different Rhodium and Iridium Triazolato Complexes

A number of different rhodium(I) and iridium(I) triazolato complexes and their oxidative addition products (triazolate = 3,5-bis(pyridine-2-yl)-1,2,4 triazolate (bpt–) and 4-amino-3,5-bis(pyridine-2-yl)-1,2,4-triazolate (bpt-NH–)) were prepared and characterized by means of IR and 1HNMR spectroscopy, elemental analysis and computational chemistry methods. The oxidative addition reactions of these complexes with iodomethane in different solvents indicated simple second-order kinetics with the faster reactions in the more polar solvents (1.44(7) × 10–2 L mol–1 s–1 in dichloromethane compared with 9.2(5) × 10–4 L mol–1 s–1 in benzene for iridium bpt-NH). 1HNMRdata and density functional theory calculations illustrate that the coordination of the metal centre in [M(bpt-NH)(cod)] (M = Rh or Ir) occurs via the amine moiety and a nitrogen of a pyridine ring.Keywords: Rhodium(I), Iridium(I), Triazole, Cyclooctadiene, Oxidative Addition, Methyl Iodide, DFTAttached PDF and Supplementary Fil

Electricity supply industry modeling for multiple objectives under demand growth uncertainty

Appropriate energy–environment–economic (E3) modelling provides key information for policy makers in the electricity supply industry (ESI) faced with navigating a sustainable development path. Key challenges include engaging with stakeholder values and preferences, and exploring trade-offs between competing objectives in the face of underlying uncertainty. As a case study we represent the South African ESI using a partial equilibrium E3 modelling approach, and extend the approach to include multiple objectives under selected future uncertainties. This extension is achieved by assigning cost penalties to non-cost attributes to force the model's least-cost objective function to better satisfy non-cost criteria. This paper incorporates aspects of flexibility to demand growth uncertainty into each future expansion alternative by introducing stochastic programming with recourse into the model. Technology lead times are taken into account by the inclusion of a decision node along the time horizon where aspects of real options theory are considered within the planning process. Hedging in the recourse programming is automatically translated from being purely financial, to include the other attributes that the cost penalties represent. From a retrospective analysis of the cost penalties, the correct market signals, can be derived to meet policy goal, with due regard to demand uncertainty

A comparative study to determine the shock absorption ability of two popular mouth guards available on the South African market

It is expected that most mouth guards will provide some level of protection to teeth. In this study a device was developed to measure the relative impact absorption of two different mouth guards (Proform, Type III vacuum-formed and Max, Type IV pressure laminate). Seven of each of the two types of mouth guards were made and each batch was exposed to between six and 10 impact trials.DHE