Sample positioning in neutron diffraction experiments using a multi-material fiducial marker

An alternative sample positioning method is reported for use in conjunction with sample positioning and experiment planning software systems deployed on some neutron diffraction strain scanners. In this approach, the spherical fiducial markers and location trackers used with optical metrology hardware are replaced with a specifically designed multi-material fiducial marker that requires one diffraction measurement. In a blind setting, the marker position can be determined within an accuracy of ±164 µm with respect to the instrument gauge volume. The scheme is based on a pre-determined relationship that links the diffracted peak intensity to the absolute positioning of the fiducial marker with respect to the instrument gauge volume. Two methods for establishing the linking relationship are presented, respectively based on fitting multi-dimensional quadratic functions and a cross-correlation artificial neural network

Cyber security education is as essential as “The Three R’s”

Smartphones have diffused rapidly across South African society and constitute the most dominant information and communication technologies in everyday use. That being so, it is important to ensure that all South Africans know how to secure their smart devices. This requires a high level of security awareness and knowledge. As yet, there is no formal curriculum addressing cyber security in South African schools. Indeed, it seems to be left to Universities to teach cyber security principles, and they currently only do this when students take computing-related courses. The outcome of this approach is that only a very small percentage of South Africans, i.e. those who take computing courses at University, are made aware of cyber security risks and know how to take precautions. Moreover, because this group is overwhelmingly male, this educational strategy disproportionately leaves young female South Africans vulnerable to cyber attacks. We thus contend that cyber security ought to be taught as children learn the essential “3 Rs” – delivering requisite skills at University level does not adequately prepare young South Africans for a world where cyber security is an essential skill. Starting to provide awareness and knowledge at primary school, and embedding it across the curriculum would, in addition to ensuring that people have the skills when they need them, also remove the current gender imbalance in cyber security awareness

Reason, survival, progress in eighteenth century thought 1

This article aims at an exposition of the coherence among the concepts of reason, survival and progress in eighteenth century thought (assuming that present-day, critical analyses of rationality, unlimited economic growth and the competition-generated pressures of life refer to concepts rooted in the eighteenth century). Eightienth century thought is exemplarized in the economic thought of Adam Smith and the social/political thought of Kant (with a few references to Hume’s ideas on art) in an attempt to show that the coherence among those concepts ought to be understood from the angle of the (then) important motive of conflict/competition. Conflict and competition were seen as mechanisms of progress and survival in competitive circumstances as a standard or sign of progress; rationality was directly connected with surviva

Kern probleme van die wetenskapmetodologie1

Method and science are defined as an introduction: Method is seen as a non-neutral means of arriving at scientific knowledge, while science is seen as a systematic explication with a view to better understanding reality for a fuller fulfilment of our calling

Akademie en politiek

Vroeër is die twee terreine helder onderskei, en soms deur die liberalistiese disintegrasie van kultuur en samelewing byna totaal geskei. Deesdae is die tendens om die twee ineen te laat vloei: Enersyds word van die kant van die totalitêre ideologieë (fascisme, sosialisme, kommunisme, nasionalisme) gepoog om die akademie te verpolitiseer; andersyds word deur die ewe totalitêre akademiese ekspertisme (scientisme en tegnokrasie) hard gewerk om die politiek wetenskaplik te gaan beheers

From ‘machine-world’ to ‘God-world’ - world pictures and world views 1

This article mainly consists of an analysis of the successive historical expansions of the mechanistic and the organistic world pictures into world views. In conclusion the presently popular form of the organistic world view, New Age occultism, is compared with the 'traditional' African world view. In this way the author attempts to realise three different aims: firstly to show how world pictures, developed within specific disciplines, are transformed into world views by expansionary application in other disciplines and /or cultural areas; secondly that occultism is regaining intellectual respectability by presenting itself as part of the ‘new’ organistic, scientific view of the world; and thirdly that there are strong similarities between the new Western occultism and the traditional African world view (which opens up possibilities of synthesis between these two)

Het filosofie en vakfilosofie enige betekenis vir beroepsopleiding?

In the light of increasing professionalism and utilitarianism in university training the philosophers and the subject philosophers have the responsibility to indicate the relevance of their fields of endeavour within the framework of training for the professions. The author points out the contribution of these subjects towards the undeniable intellectual enrichment and power of judgement by reference to two professions, viz. those of business manager and of medical doctor. By being professionally supportive Philosophy and subject philosophies can be strengthened by supporting amongst others neglected or under-developed professions by means of a professional philosophy. The fact that the professional world teems with philosophical problems should be brought home not only to colleagues in professional training institutions but also to those who have influence in the professional world itself

Modeling the Pulse Profiles of Millisecond Pulsars in the Second LAT Catalog of gamma-ray Pulsars

Significant gamma-ray pulsations have been detected from ~40 millisecond pulsars (MSPs) using 3 years of sky-survey data from the Fermi LAT and radio timing solutions from across the globe. We have fit the radio and gamma-ray pulse profiles of these MSPs using geometric versions of slot gap and outer gap gamma-ray emission models and radio cone and core models. For MSPs with radio and gamma-ray peaks aligned in phase we also explore low-altitude slot gap gamma-ray models and caustic radio models. The best-fit parameters provide constraints on the viewing geometries and emission sites. While the exact pulsar magnetospheric geometry is unknown, we can use the increased number of known gamma-ray MSPs to look for significant trends in the population which average over these uncertainties.Comment: 4 pages, 2 figures, to appear in the proceedings of the 5th International Symposium on High-Energy Astronom

Modeling and Maximum Likelihood Fitting of Gamma-Ray and Radio Light Curves of Millisecond Pulsars Detected with Fermi

Pulsed gamma rays have been detected with the Fermi Large Area Telescope (LAT) from more than 20 millisecond pulsars (MSPs), some of which were discovered in radio observations of bright, unassociated LAT sources. We have fit the radio and gamma-ray light curves of 19 LAT-detected MSPs in the context of geometric, outer-magnetospheric emission models assuming the retarded vacuum dipole magnetic field using a Markov chain Monte Carlo maximum likelihood technique. We find that, in many cases, the models are able to reproduce the observed light curves well and provide constraints on the viewing geometries that are in agreement with those from radio polarization measurements. Additionally, for some MSPs we constrain the altitudes of both the gamma-ray and radio emission regions. The best-fit magnetic inclination angles are found to cover a broader range than those of non-recycled gamma-ray pulsars.Comment: 4 pages, 3 figures, 2011 Fermi Symposium proceedings - eConf C110509 -- v2 corrects caption of Figure 1, v3 corrects missing fil