University of Exeter

About: University of Exeter is a education organization based out in Exeter, United Kingdom. It is known for research contribution in the topics: Population & Context (language use). The organization has 15820 authors who have published 50650 publications receiving 1793046 citations. The organization is also known as: Exeter University & University of the South West of England.

The VMC Survey - I. Strategy and First Data

Abstract: Context. The new VISual and Infrared Telescope for Astronomy (VISTA) has started operations. Over its first five years it will be col lecting data for six Public Surveys, one of which is the near-infrared Y JKs VISTA survey of the Magellanic Clouds system (VMC). This survey comprises the Large Magellanic Cloud (LMC), the Small Magellanic Cloud, the Magellanic Bridge connecting the two galaxies and two fields in the Magellanic Stream. Aims. This paper provides an overview of the VMC survey strategy and presents first science results. The main goals of the VMC sur vey are the determination of the spatially-resolved star-form ation history and the three-dimensional structure of the Magellanic system. The VMC survey is therefore designed to reach stars as faint as the ol dest main sequence turn-off point and to constrain the mean magnitude of pulsating variables such as RR Lyrae stars and Cepheids. This paper focuses on observations of VMC fields in the LMC obtained between November 2009 and March 2010. These observations correspond to a completeness of 7% of the planned LMC fields. Methods. The VMC data are comprised of multi-epoch observations which are executed following specific time constraints. The data were reduced using the VISTA Data Flow System pipeline with source catalogues, including astrometric and photometric corrections, produced and made available via the VISTA Science Archive. The VMC data will be released to the astronomical community following the European Southern Observatory’s Public Survey policy. The analysis of the data shows that the sensitivity in each wave band agrees with expectations. Uncertainties and completeness of the data are also derived. Results. The first science results, aimed at assessing the scientific q uality of the VMC data, include an overview of the distribution of stars in colour-magnitude and colour-colour diagrams, the detection of planetary nebulae and stellar clusters, and the Ks band light-curves of variable stars. Conclusions. The VMC survey represents a tremendous improvement, in spatial resolution and sensitivity, on previous panoramic observations of the Magellanic system in the near-infrared, providing a powerful complement to deep observations at other wavelengths.

The importance of radiative feedback for the stellar initial mass function

Abstract: We investigate the effect of radiative feedback on the star formation process using radiation hydrodynamical simulations We repeat the previous hydrodynamical star cluster formation simulations of Bate et al and Bate & Bonnell, but we use a realistic gas equation of state and radiative transfer in the flux-limited diffusion approximation rather than the original barotropic equation of state Whereas star formation in the barotropic simulations continued unabated until the simulations stopped, we find that radiative feedback, even from low-mass stars, were essentially terminates the production of new objects within low-mass dense molecular cloud cores after roughly one local dynamical time Radiative feedback also dramatically decreases the propensity of massive circumstellar discs to fragment and inhibits fragmentation of other dense gas (eg filaments) close to existing protostellar objects These two effects decrease the numbers of protostars formed by a factor of ≈4 compared with the original hydrodynamical simulations using the barotropic equation of state In particular, whereas the original simulations produced more brown dwarfs than stars, the radiative feedback results in a ratio of stars to brown dwarfs of approximately 5:1, in much better agreement with observations Most importantly, we find that although the characteristic stellar mass in the original calculations scaled linearly with the initial mean Jeans mass in the clouds, when radiative feedback is included the characteristic stellar mass is indistinguishable for the two calculations, regardless of the initial Jeans mass of the clouds We thus propose that the reason the observed initial mass function appears to be universal in the local Universe is due to self-regulation of the star formation process by radiative feedback We present an analytic argument showing how a characteristic mass may be derived that is relatively independent of initial conditions such as the cloud's density

Validating a new non-penetrating sham acupuncture device: two randomised controlled trials

Abstract: For clinical trials of acupuncture, it would be desirable to have a sham procedure that is indistinguishable from the real treatment, yet inactive. A sham needle has been designed which telescopes instead of penetrating the skin. The Park Sham Device involves an improved method of supporting the sham needle and requires validation. The objective of these studies was to test whether the sham procedure using the new device was 1) indistinguishable from the same procedure using real needles in acupuncture naive subjects, and 2) inactive, where the specific needle sensation (de qi) is taken as a surrogate measure of activity. The studies were designed as subject and assessor blind, randomised controlled trials. Study 1) included 58 patients enrolled in a clinical trial of acupuncture for acute stroke. Study 2) included 63 healthy, acupuncture naive, adult volunteers. The interventions used were real or sham acupuncture using the Park Sham Device. Study 1) was set in a district general hospital, and study 2) in a university laboratory. The outcome measure in study 1) was the form of treatment that patients believed they had received. In study 2) the outcome measure was experience of de qi, as judged by three acupuncture experts. No patient in either group(study 1) believed he or she had been treated with the sham needle. In 40 volunteers (study 2) for whom experts achieved consensus, the relative risk of experiencing de qi with real acupuncture to that with sham acupuncture was 15.38 (95% CI 2.26 to 104.86). The inter-rater reliability of all 13 experts (study 2), calculated from their judgements on 10 subjects selected by randomisation, was 0.52 (95% CI 0.19 to 0.61). In conclusion, the results suggest that the procedure using the new device is indistinguishable from the same procedure using real needles in acupuncture naive subjects, and is inactive, where the specific needle sensation (de qi) is taken as a surrogate measure of activity. It is therefore a valid control for acupuncture trials. The findings also lend support to the existence of de qi, a major concept underlying traditional Chinese acupuncture.

A MOPSO algorithm based exclusively on pareto dominance concepts

Abstract: In extending the Particle Swarm Optimisation methodology to multi-objective problems it is unclear how global guides for particles should be selected. Previous work has relied on metric information in objective space, although this is at variance with the notion of dominance which is used to assess the quality of solutions. Here we propose methods based exclusively on dominance for selecting guides from a non-dominated archive. The methods are evaluated on standard test problems and we find that probabilistic selection favouring archival particles that dominate few particles provides good convergence towards and coverage of the Pareto front. We demonstrate that the scheme is robust to changes in objective scaling. We propose and evaluate methods for confining particles to the feasible region, and find that allowing particles to explore regions close to the constraint boundaries is important to ensure convergence to the Pareto front.

Leadership as social identity management: Introducing the Identity Leadership Inventory (ILI) to assess and validate a four-dimensional model

Abstract: This work has been supported by a grant (FL110100199) from the Australian Research Council awarded to the second author, a grant from the Research Foundation Flanders awarded to the fifth author, and a grant from the National Natural Science Foundation of China (NSFC no. 70962001) awarded to the sixth author.