University of St Andrews

About: University of St Andrews is a education organization based out in St Andrews, Fife, United Kingdom. It is known for research contribution in the topics: Population & Laser. The organization has 16260 authors who have published 43364 publications receiving 1636072 citations. The organization is also known as: St Andrews University & University of St. Andrews.

Old World megadroughts and pluvials during the Common Era

Abstract: Climate model projections suggest widespread drying in the Mediterranean Basin and wetting in Fennoscandia in the coming decades largely as a consequence of greenhouse gas forcing of climate. To place these and other “Old World” climate projections into historical perspective based on more complete estimates of natural hydroclimatic variability, we have developed the “Old World Drought Atlas” (OWDA), a set of year-to-year maps of tree-ring reconstructed summer wetness and dryness over Europe and the Mediterranean Basin during the Common Era. The OWDA matches historical accounts of severe drought and wetness with a spatial completeness not previously available. In addition, megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes. The OWDA provides new data to determine the causes of Old World drought and wetness and attribute past climate variability to forced and/or internal variability.

An implementation research agenda

Abstract: In October 2006, the Chief Medical Officer (CMO) of England asked Professor Sir John Tooke to chair a High Level Group on Clinical Effectiveness in response to the chapter 'Waste not, want not' in the CMOs 2005 annual report 'On the State of the Public Health'. The high level group made recommendations to the CMO to address possible ways forward to improve clinical effectiveness in the UK National Health Service (NHS) and promote clinical engagement to deliver this. The report contained a short section on research needs that emerged from the process of writing the report, but in order to more fully identify the relevant research agenda Professor Sir John Tooke asked Professor Martin Eccles to convene an expert group – the Clinical Effectiveness Research Agenda Group (CERAG) – to define the research agenda. The CERAG's terms of reference were 'to further elaborate the research agenda in relation to pursuing clinically effective practice within the (UK) National Health Service'. This editorial presents the summary of the CERAG report and recommendations.

Forty eclipsing binaries in the Small Magellanic Cloud: fundamental parameters and Cloud distance

Abstract: We have conducted a programme to determine the fundamental parameters of a substantial number of eclipsing binaries of spectral types O and B in the Small Magellanic Cloud (SMC). New spectroscopic data, obtained with the two- degree- field (2dF) multi- object spectrograph on the 3.9- m Anglo- Australian Telescope, have been used in conjunction with photometry from the Optical Gravitational Lens Experiment (OGLE- II) data base of SMC eclipsing binaries. Previously we reported results for 10 systems; in this second and concluding paper we present spectral types, masses, radii, temperatures, surface gravities and luminosities for the components of a further 40 binaries. The uncertainties are typically +/- 10 per cent on masses, +/- 4 per cent on radii and +/- 0.07 on log L. The full sample of 50 OB- type eclipsing systems is the largest single set of fundamental parameters determined for high- mass binaries in any galaxy. We find that 21 of the systems studied are in detached configurations, 28 are in semidetached post- mass- transfer states, and one is a contact binary.The overall properties of the detached systems are consistent with theoretical models for the evolution of single stars with SMC metal abundances (Z similar or equal to 0.004); in particular, observed and evolutionary masses are in excellent agreement. Although there are no directly applicable published models, the overall properties of the semidetached systems are consistent with them being in the slow phase of mass transfer in case A. About 40 per cent of these semidetached systems show photometric evidence of orbital- phase- dependent absorption by a gas stream falling from the inner Lagrangian point on the secondary star towards the primary star. This sample demonstrates that case- A mass transfer is a common occurrence amongst high- mass binaries with initial orbital periods P less than or similar to 5 d, and that this slow phase has a comparable duration to the detached phase preceding it.Each system provides a primary distance indicator. We find a mean distance modulus to the SMC of 18.91 +/- 0.03 +/- 0.1 (internal and external uncertainties; D = 60.6 +/- 1.0 +/- 2.8 kpc). This value represents one of the most precise available determinations of the distance to the SMC.

An Introduction to Close Binary Stars

Abstract: Binary systems of stars are as common as single stars. They are of fundamental importance because they allow stellar masses, radii and luminosities to be measured directly, and explain a host of diverse and energetic phenomena including X-ray binaries, cataclysmic variables, novae, symbiotic stars, and some types of supernovae. This 2001 book was the first to provide a pedagogical and comprehensive introduction to binary stars. It combines theory and observations at all wavelengths to develop a unified understanding of binaries of all categories. It comprehensively reviews methods for calculating orbits, the Roche model, ideas about mass exchange and loss, methods for analysing light curves, the masses and dimensions of different binary systems, and imaging the surfaces of stars and accretion structures. This book provides a thorough introduction to the subject for advanced undergraduate and graduate students. Researchers will also find this to be an authoritative reference.

Stressing the group: social identity and the unfolding dynamics of responses to stress.

Abstract: Participants in the British Broadcasting Corporation (BBC) prison study were randomly assigned to high-status (guard) and low-status (prisoner) groups. Structural interventions increased the prisoners' sense of shared group identity and their willingness to challenge the power of the guards. Psychometric, physiological, behavioral, and observational data support the hypothesis that identity-based processes also affected participants' experience of stress. As prisoners' sense of shared identity increased, they provided each other with more social support and effectively resisted the adverse effects of situational stressors. As guards' sense of shared identity declined, they provided each other with less support and succumbed to stressors. Findings support an integrated social identity model of stress that addresses intragroup and intergroup dynamics of the stress process.