Symmetry of re-entrant tetragonal phase in Ba1-xNaxFe2As2: Magnetic versus orbital ordering mechanism

Magneto-structural phase transitions in Ba1-xAxFe2As2 (A = K, Na) materials are discussed for both magnetically and orbitally driven mechanisms, using a symmetry analysis formulated within the Landau theory of phase transitions. Both mechanisms predict identical orthorhombic space-group symmetries for the nematic and magnetic phases observed over much of the phase diagram, but they predict different tetragonal space-group symmetries for the newly discovered re-entrant tetragonal phase in Ba1-xNaxFe2As2 (x ~ 0.24-0.28). In a magnetic scenario, magnetic order with moments along the c-axis, as found experimentally, does not allow any type of orbital order, but in an orbital scenario, we have determined two possible orbital patterns, specified by P4/mnc1' and I4221' space groups, which do not require atomic displacements relative to the parent I4/mmm1' symmetry and, in consequence, are indistinguishable in conventional diffraction experiments. We demonstrate that the three possible space groups are however, distinct in resonant X-ray Bragg diffraction patterns created by Templeton & Templeton scattering. This provides an experimental method of distinguishing between magnetic and orbital models

Statin therapy in critical illness : an international survey of intensive care physicians' opinions, attitudes and practice

Background Pleotropic effects of statins on inflammation are hypothesised to attenuate the severity of and possibly prevent the occurrence of the host inflammatory response to pathogen and infection-related acute organ failure. We conducted an international survey of intensive care physicians in Australia, New Zealand (ANZ) and United Kingdom (UK). The aims of the survey were to assess the current prescribing practice patterns, attitudes towards prescribing statin therapy in critically ill patients and opinions on the need for an interventional trial of statin therapy in critically ill patients. Methods Survey questions were developed through an iterative process. An expert group reviewed the resulting 26 items for face and content validity and clarity. The questions were further refined following pilot testing by ICU physicians from Australia, Canada and the UK. We used the online Smart SurveyTM software to administer the survey. Results Of 239 respondents (62 from ANZ and 177 from UK) 58% worked in teaching hospitals; most (78.2%) practised in ‘closed’ units with a mixed medical and surgical case mix (71.0%). The most frequently prescribed statins were simvastatin (77.6%) in the UK and atorvastatin (66.1%) in ANZ. The main reasons cited to explain the choice of statin were preadmission prescription and pharmacy availability. Most respondents reported never starting statins to prevent (65.3%) or treat (89.1%) organ dysfunction. Only a minority (10%) disagreed with a statement that the risks of major side effects of statins when prescribed in critically ill patients were low. The majority (84.5%) of respondents strongly agreed that a clinical trial of statins for prevention is needed. More than half (56.5%) favoured rates of organ failure as the primary outcome for such a trial, while a minority (40.6%) favoured mortality. Conclusions Despite differences in type of statins prescribed, critical care physicians in the UK and ANZ reported similar prescription practices. Respondents from both communities agreed that a trial is needed to test whether statins can prevent the onset of new organ failure in patients with sepsis

FZZ Scattering

We study the duality between the two dimensional black hole and the sine-Liouville conformal field theories via exact operator quantization of a classical scattering problem. The ideas are first illustrated in Liouville theory, which is dual to itself under the interchange of the Liouville parameter b by 1/b. In both cases, a classical scattering problem does not determine uniquely the quantum reflection coefficient. The latter is only fixed by assuming that the dual scattering problem has the same reflection coefficient. We also discuss the relation of this approach to the method that exploits the parafermionic symmetry of the model to compute the reflection coefficient.Comment: 19 pages, JHEP style. v2: Minor changes in the proposed field of sine-Liouville type, new section discussing the relation with parafermionic symmetry, references adde

Measuring tourists' satisfaction with quality of life issues at an arts festival

Purpose: The purpose of this paper is to measure tourists' satisfaction with quality of life issues at an arts festival - the Aardklop National Arts Festival in Potchefstroom. Problem investigated: Understanding satisfaction with quality of life issues could assist Festival organizers and other businesses to improve services for tourists by tailoring these to meet their needs. Satisfied tourists spread positive word-of-mouth communication and are more likely to return in the future. Methodology: A self-administered survey developed and validated by Neal, Sirgy and Uysal (1999:156 & 2004:245) was fielded at the 2007 Aardklop National Arts Festival in Potchefstroom. The target population included all visitors to the Festival who were staying for two or more days, and who had travelled to Potchefstroom from elsewhere. Findings and implications: Respondents were satisfied with travel / tourism services and experiences at the Festival, and with their leisure time and life in general. However, certain things at the Festival led to lowered levels of satisfaction. Demographically, respondents did not differ significantly in their levels of satisfaction with travel / tourism services, travel / tourism experiences, leisure life, and life in general at the Festival except in terms of population group and region from which they came. Organizers of the Festival and other businesses should take cognizance of the fact that all parties involved in providing services to tourists attending an arts festival impact on their satisfaction levels with travel / tourism services and experiences - and ultimately also on their quality of life. Tourists attending the arts festival are not homogenous and differ substantially in terms of their demographic profile. Tourist service providers should tailor their offerings in order to satisfy the varied needs of the different types of tourist attending the Festival. Originality and value of the research: This research focused on measuring tourists' satisfaction with quality of life issues at an arts festival. Such research has never before been conducted in South Africa; the results contribute to the deeper insight of interested parties (such as the tourism industry and arts festival managers) into what they need to offer at such events

Effect of sheared flows on classical and neoclassical tearing modes

The influence of toroidal sheared equilibrium flows on the nonlinear evolution of classical and neoclassical tearing modes is studied through numerical solutions of a set of reduced generalized MHD equations that include viscous force effects based on neoclassical closures. In general, differential flow is found to have a strong stabilizing influence leading to lower saturated island widths for the classical tearing mode and reduced growth rates for the neoclassical mode. Velocity shear, on the other hand, is seen to make a destabilizing contribution

Acceleration of bouncing balls in external fields

We introduce two models, the Fermi-Ulam model in an external field and a one dimensional system of bouncing balls in an external field above a periodically oscillating plate. For both models we investigate the possibility of unbounded motion. In a special case the two models are equivalent

Report of the International Society of Hypertension (ISH) Hypertension Teaching Seminar organized by the ISH Africa Regional Advisory Group: Maputo, Mozambique, 2016

The International Society of Hypertension (ISH), in fulfilment of its mission of promoting hypertension control and prevention and also of advancing knowledge globally, organizes hypertension teaching seminars or ‘summer schools’ worldwide through the ISH Regional Advisory Groups. In Africa, seven of such seminars have been organized. This is a report of the eighth seminar held in Maputo, Mozambique, April, 2016. The seminar was attended by over 65 participants from 11 African countries. The Faculty consisted of 11 international hypertension experts. The eighth African hypertension seminar was a great success as confirmed by a pre- and post-test questionnaire