18 research outputs found

    Prospects for asteroseismology

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    The observational basis for asteroseismology is being dramatically strengthened, through more than two years of data from the CoRoT satellite, the flood of data coming from the Kepler mission and, in the slightly longer term, from dedicated ground-based facilities. Our ability to utilize these data depends on further development of techniques for basic data analysis, as well as on an improved understanding of the relation between the observed frequencies and the underlying properties of the stars. Also, stellar modelling must be further developed, to match the increasing diagnostic potential of the data. Here we discuss some aspects of data interpretation and modelling, focussing on the important case of stars with solar-like oscillations.Comment: Proc. HELAS Workshop on 'Synergies between solar and stellar modelling', eds M. Marconi, D. Cardini & M. P. Di Mauro, Astrophys. Space Sci., in the press Revision: correcting abscissa labels on Figs 1 and

    Look after they leap : illustrating the value of retrospective reports in employee turnover

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    The prevailing methodology for studying employee turnover is limited because it emphasizes prediction rather than understanding. This paper critiques this methodology and draws out the implications of an alternative: retrospective self-reporting, by actual leavers. Retrospective self-reporting has three main advantages. First, it allows direct assessment of actual incidents of turnover, so interventions can be informed by accounts of real events, instead of being based on inference. Second, it offers insight into the dynamic character of decisions to quit, which are often unpredictable or precipitated by sudden events. Third, it allows for assessment of the role of non-work factors. This makes a methodological contribution, allowing greater insight into the decision to quit, which is ontologically, socially and dynamically complex. It has implications for how we construe and manage turnover. The argument is illustrated by a recent study of 352 UK National Health Service nurse leavers but has wider implications for turnover in the public sector

    Phylogeny and divergence dating of the ladybird beetle tribe Coccinellini Latreille (Coleoptera: Coccinellidae: Coccinellinae)

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    International audienceWe reconstruct a comprehensively sampled molecular phylogeny for the second most species-rich tribe of the ladybird beetle family Coccinellidae, the charismatic Coccinellini. We analysed a dataset consisting of five nuclear and three mitochondrial gene fragments from 150 taxa to provide a detailed phylogeny and estimates of historical divergence times using Bayesian relaxed clocks and primary fossil calibrations and an assessment of the evolution of feeding habits. The results of phylogenetic analyses provide strong support for the monophyly of the tribe Coccinellini, highlight the existence of four major clades and most sampled Coccinellini genera (30 out of 34) were recovered monophyletic. Our dating analyses suggest an Early Cretaceous origin for Coccinellidae at ca. 140 millions years ago (Ma) and a Late Cretaceous origin for the tribe Coccinellini at ca. 83.8 Ma. Ancestral character state estimation of feeding habits highlights a high level of phylogenetic niche conservatism on aphids and indicates that the most common recent ancestor of Coccinellini likely also fed on aphids. Our reconstruction of feeding habits and assessment of the aphid fossil record suggests that the diversification of Coccinellini paralleled that of Aphididae, although with substantial variation in host-breadth and the tendency for a few specialized lineages towards non-aphid feeding
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