341 research outputs found

    Uncertainty in an emissions constrained world: Case Austria

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    The current task under the United Nations Framework Convention on Climate Change [UN FCCC] is to agree on a climate treaty that comes into force in 2012, the year in which commitments under the Kyoto Protocol will cease. Leaders of the world's major industrialized countries have formally agreed in the wake of the 2009 UN climate change conference in Copenhagen that the average global temperature should not be permitted to increase by more than 2 degrees Celsius from its preindustrial level. Compliance with this temperature target can be expressed equivalently in terms of limiting cumulative greenhouse [GHG] emissions, for example, up to 2050, while considering the risk of exceeding this target (Meinshausen et al., 2009). The emission reductions required are substantial: 50.80% below the 1990 level at the global scale, with even greater reductions for industrialized countries (Jonas et al., 2010a). Although the issue of translating an approved global emissions constraint to the sub-global level and allocating global emission shares to countries is still unsettled, a crucial question arising and still to be answered is: how should we deal with the uncertainty associated with the accounting of emissions for compliance purposes? The accounting of emissions, when bottom-up inventory estimates are compared with top-down model-derived constraints, could force us to admit considerable uncertainty due to still existing accounting gaps. Minimizing the risk of exceeding an agreed global average temperature target may demand significant undershooting of the most uncertain emission estimates to ensure that global overall emissions do not exceed the agreed target

    Whole Earth Telescope observations of the pulsating subdwarf B star PG 0014+067

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    PG 0014+067 is one of the most promising pulsating subdwarf B stars for seismic analysis, as it has a rich pulsation spectrum. The richness of its pulsations, however, poses a fundamental challenge to understanding the pulsations of these stars, as the mode density is too complex to be explained only with radial and nonradial low degree (l < 3) p-modes without rotational splittings. One proposed solution, for the case of PG 0014+067 in particular, assigns some modes with high degree (l=3). On the other hand, theoretical models of sdB stars suggest that they may retain rapidly rotating cores, and so the high mode density may result from the presence of a few rotationally-split triplet (l=1), quintuplet (l=2) modes, along with radial (l=0) p-modes. To examine alternative theoretical models for these stars, we need better frequency resolution and denser longitude coverage. Therefore, we observed this star with the Whole Earth Telescope for two weeks in October 2004. In this paper we report the results of Whole Earth Telescope observations of the pulsating subdwarf B star PG 0014+067. We find that the frequencies seen in PG 0014+067 do not appear to fit any theoretical model currently available; however, we find a simple empirical relation that is able to match all of the well-determined frequencies in this star.Comment: 19 pages, preprint of paper accepted for publication in The Astrophysical Journa

    Towards ensemble asteroseismology of the young open clusters Chi Persei and NGC 6910

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    As a result of the variability survey in Chi Persei and NGC6910, the number of Beta Cep stars that are members of these two open clusters is increased to twenty stars, nine in NGC6910 and eleven in Chi Persei. We compare pulsational properties, in particular the frequency spectra, of Beta Cep stars in both clusters and explain the differences in terms of the global parameters of the clusters. We also indicate that the more complicated pattern of the variability among B type stars in Chi Persei is very likely caused by higher rotational velocities of stars in this cluster. We conclude that the sample of pulsating stars in the two open clusters constitutes a very good starting point for the ensemble asteroseismology of Beta Cep-type stars and maybe also for other B-type pulsators.Comment: 4 pages, Astronomische Nachrichten, HELAS IV Conference, Arecife, Lanzarote, Feb 2010, submitte

    Phonons and related properties of extended systems from density-functional perturbation theory

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    This article reviews the current status of lattice-dynamical calculations in crystals, using density-functional perturbation theory, with emphasis on the plane-wave pseudo-potential method. Several specialized topics are treated, including the implementation for metals, the calculation of the response to macroscopic electric fields and their relevance to long wave-length vibrations in polar materials, the response to strain deformations, and higher-order responses. The success of this methodology is demonstrated with a number of applications existing in the literature.Comment: 52 pages, 14 figures, submitted to Review of Modern Physic

    Random-phase approximation and its applications in computational chemistry and materials science

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    The random-phase approximation (RPA) as an approach for computing the electronic correlation energy is reviewed. After a brief account of its basic concept and historical development, the paper is devoted to the theoretical formulations of RPA, and its applications to realistic systems. With several illustrating applications, we discuss the implications of RPA for computational chemistry and materials science. The computational cost of RPA is also addressed which is critical for its widespread use in future applications. In addition, current correction schemes going beyond RPA and directions of further development will be discussed.Comment: 25 pages, 11 figures, published online in J. Mater. Sci. (2012

    Towards an international language for incontinence-associated dermatitis (IAD): design and evaluation of psychometric properties of the Ghent Global IAD Categorization Tool (GLOBIAD) in 30 countries

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    Background Incontinence-associated dermatitis (IAD) is a specific type of irritant contact dermatitis with different severity levels. An internationally accepted instrument to assess the severity of IAD in adults, with established diagnostic accuracy, agreement and reliability, is needed to support clinical practice and research. Objectives To design the Ghent Global IAD Categorization Tool (GLOBIAD) and evaluate its psychometric properties. Methods The design was based on expert consultation using a three-round Delphi procedure with 34 experts from 13 countries. The instrument was tested using IAD photographs, which reflected different severity levels, in a sample of 823 healthcare professionals from 30 countries. Measures for diagnostic accuracy (sensitivity and specificity), agreement, interrater reliability (multirater Fleiss kappa) and intrarater reliability (Cohen’s kappa) were assessed. Results The GLOBIAD consists of two categories based on the presence of persistent redness (category 1) and skin loss (category 2), both of which are subdivided based on the presence of clinical signs of infection. The agreement for differentiating between category 1 and category 2 was 0 86 [95% confidence interval (CI) 0 86–0 87], with a sensitivity of 90% and a specificity of 84%. The overall agreement was 0 55 (95% CI 0 55–0 56). The Fleiss kappa for differentiating between category 1 and category 2 was 0 65 (95% CI 0 65–0 65). The overall Fleiss kappa was 0 41 (95% CI 0 41–0 41). The Cohen’s kappa for differentiating between category 1 and category 2 was 0 76 (95% CI 0 75–0 77). The overall Cohen’s kappa was 0 61 (95% CI 0 59–0 62). Conclusions The development of the GLOBIAD is a major step towards a better systematic assessment of IAD in clinical practice and research worldwide. However, further validation is needed.info:eu-repo/semantics/acceptedVersio

    Performance of the CMS Cathode Strip Chambers with Cosmic Rays

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    The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns
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