553 research outputs found

    How well do CMIP5 Earth System Models simulate present climate conditions in Europe and Africa?

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    This study provides a comprehensive evaluation of seven Earth System Models (ESMs) from the Coupled Model Intercomparison Project Phase 5 in present climate conditions from a downscaling perspective, taking into account the requirements of both statistical and dynamical approaches. ECMWF's ERA-Interim reanalysis is used as reference for an evaluation of circulation, temperature and humidity variables on daily timescale, which is based on distributional similarity scores. To additionally obtain an estimate of reanalysis uncertainty, ERA-Interim's deviation from the Japanese Meteorological Agency JRA-25 reanalysis is calculated. Areas with considerable differences between both reanalyses do not allow for a proper assessment, since ESM performance is sensitive to the choice of reanalysis. For use in statistical downscaling studies, ESM performance is computed on the grid-box scale and mapped over a large spatial domain covering Europe and Africa, additionally highlighting those regions where significant distributional differences remain even for the centered/zero-mean time series. For use in dynamical downscaling studies, performance is specifically assessed along the lateral boundaries of the three CORDEX domains defined for Europe, the Mediterranean Basin and Africa.S.B. would like to thank the CSIC JAE-PREDOC programme for financial support. J.F. and J.M.G. acknowledge financial support from the Spanish R&D&I programme through grants CGL2010-22158-C02 (CORWES project) and CGL2010-21869 (EXTREMBLES project) and from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement 243888 (FUME Project).Peer Reviewe

    Comments on "global and regional comparison of daily 2-m and 1000-hPa maximum and minimum temperatures in three global reanalyses"

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    Pitman and Perkins claimed that instantaneous 2-m air temperatures from different reanalysis products largely disagree over widespread regions of the globe and that, because of their much smaller differences, temperatures at 1000 hPa should be preferably used. This comment shows that this claim is based on erroneous results. © 2012 American Meteorological Society.S.B. would like to thank the 'Consejo Superior de Investigaciones Científicas' (CSIC) pre- doctoral program 'JAE-PREDOC' for funding.Peer Reviewe

    Cost Projection Methods for the Shortest Path Problem with Crossing Costs

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    Validity-Guided Synthesis of Reactive Systems from Assume-Guarantee Contracts

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    Automated synthesis of reactive systems from specifications has been a topic of research for decades. Recently, a variety of approaches have been proposed to extend synthesis of reactive systems from proposi- tional specifications towards specifications over rich theories. We propose a novel, completely automated approach to program synthesis which reduces the problem to deciding the validity of a set of forall-exists formulas. In spirit of IC3 / PDR, our problem space is recursively refined by blocking out regions of unsafe states, aiming to discover a fixpoint that describes safe reactions. If such a fixpoint is found, we construct a witness that is directly translated into an implementation. We implemented the algorithm on top of the JKind model checker, and exercised it against contracts written using the Lustre specification language. Experimental results show how the new algorithm outperforms JKinds already existing synthesis procedure based on k-induction and addresses soundness issues in the k-inductive approach with respect to unrealizable results.Comment: 18 pages, 5 figures, 2 table

    Emerging European winter precipitation pattern linked to atmospheric circulation changes over the North Atlantic region in recent decades

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    Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 44 (2017): 8557–8566, doi:10.1002/2017GL074188.Dominant European winter precipitation patterns over the past century, along with their associated extratropical North Atlantic circulation changes, are evaluated using cluster analysis. Contrary to the four regimes traditionally identified based on daily wintertime atmospheric circulation patterns, five distinct seasonal precipitation regimes are detected here. Recurrent precipitation patterns in each regime are linked to changes in atmospheric blocking, storm track, and sea surface temperatures across the North Atlantic region. Multidecadal variability in the frequency of the precipitation patterns reveals more (fewer) winters with wet conditions in northern (southern) Europe in recent decades and an emerging distinct pattern of enhanced wintertime precipitation over the northern British Isles. This pattern has become unusually common since the 1980s and is associated with changes in moisture transport and more frequent atmospheric river events. The observed precipitation changes post-1950 coincide with changes in storm track activity over the central/eastern North Atlantic toward the northern British Isles.U.S. National Science Foundation Grant Number: AGS-1355339; NASA Physical Oceanography Program Grant Number: NNX13AM59G; WHOI2018-02-2

    Substrate specificity of CYP2D6 genetic variants

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    Genetic variation in the gene encoding CYP2D6 is used to guide drug prescribing in clinical practice. However, genetic variants in CYP2D6 show substrate-specific effects that are currently not accounted for. With a systematic literature, we retrieved 22 original studies describing in vitro experiments focusing on CYP2D6 alleles (CYP2D6*1, *2, *10 and *17) and substrates. Allele activity (clearance of the allele of interest divided by the clearance of the wildtype) was extracted. The results support the hypothesis of the existence of substrate specificity of the CYP2D6*17-allele (higher debrisoquine clearance), a subtle effect of the CYP2D6*10-allele (lower dextromethorphan clearance) but no substrate-specific effect of the CYP2D6*2-allele. Although our results support substrate specificity, for most substrates data are too sparse and require further studies.Personalised Therapeutic

    Variable rate spraying in varied micro-meteorological conditions

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    This study evaluated effects of crosswind on the variable rate sprayer application treatments spray coverage and deposition on different citrus canopy sizes.  The axial-fan airblast sprayer retrofitted with variable liquid- and air-assist rates was field-tested with different crosswind conditions on small (about 2 m tall and < 1.5 m wide) and medium-sized (about 3 m tall and < 2.5 m wide) canopies.  Crosswinds of 1.3, 2.7, and 4.0 ms-1 on the canopies being sprayed were generated using the stationary conical air shaker as the air blower unit.  Water sensitive papers (WSPs) were used to collect droplet deposits and image processing software was used to analyze the WSPs scanned at 600 dpi.  Percent spray coverage on the WSPs was found to be one of the most suited parameters to evaluate the effectiveness of spray application treatments.  Overall, the variable rate spray application treatments had comparable spray coverage on respective canopies (front, middle, and across WSP locations in the canopy) during all crosswind conditions.  For both types of canopies, spray coverage was higher on the canopy front and decreased as the spray penetrated inside (i.e. canopy middle) and across.  Due to coalescing, larger droplets (Dv,0.5 [volume median diameter] = 838 to 2,624 µm) were formed on the WSPs located on canopy front, whereas coalescing reduced as the spray penetrated inside (Dv,0.5 = 391 to 1,625 µm on canopy middle) and across the canopy (Dv,0.5 = 307 to 508 µm).    Keywords: airblast sprayer, adjustable air-assistance, crosswind, spray coverage, citru
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