539 research outputs found

    Fixing soft margins

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    Non-parametric tolerance limits are employed to calculate soft margins such as advocated in Williamson's target zone proposal. In particular, the tradeoff between softness and zone width is quantified. This may be helpful in choosing appropriate margins. Furthermore, it offers policymakers a framework for reference in the case of changing exchange rate policy. The empirical applications include an evaluation of the EMS zone width. We also show that the procedures for calculating the soft margins are robust against alternative data-generating mechanisms

    Hydropower Scheduling Toolchains:Comparing Experiences in Brazil, Norway,and USA and Implications for Synergistic Research

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    While hydropower scheduling is a well-defined problem, there are institutional differences that need to be identified to promoteconstructive and synergistic research. We study how established toolchains of computer models are organized to assist operational hydro-power scheduling in Brazil, Norway, and the United States’Colorado River System (CRS). These three systems have vast hydropowerresources, with numerous, geographically widespread, and complex reservoir systems. Although the underlying objective of hydropowerscheduling is essentially the same, the systems are operated in different market contexts and with different alternative uses of water, where thestakeholders’objectives clearly differ. This in turn leads to different approaches when it comes to the scope, organization, and use of modelsfor operational hydropower scheduling and the information flow between the models. We describe these hydropower scheduling toolchains,identify the similarities and differences, and shed light on the original ideas that motivated their creation. We then discuss the need to improveand extend the current toolchains and the opportunities to synergistic research that embrace those contextual differences.Hydropower Scheduling Toolchains:Comparing Experiences in Brazil, Norway,and USA and Implications for Synergistic ResearchacceptedVersio

    Associations of C-reactive protein with measures of obesity, insulin resistance, and subclinical atherosclerosis in healthy, middle-aged women

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    Obesity, the insulin resistance syndrome, and atherosclerosis are closely linked and may all be determinants of an increased acute-phase response. In this study, we examined the relationship of C-reactive protein (CRP) with measures of obesity, variables of the insulin resistance syndrome, and intima-media thickness of the common carotid arteries in 186 healthy, middle-aged women selected from the general population. Associations were assessed by regression analysis. CRP was strongly associated with body mass index (BMI) and waist circumference. CRP was also associated with other variables of the insulin resistance syndrome, including blood pressure, insulin, high density lipoprotein cholesterol, triglycerides, apolipoprotein A1 (inversely), plasminogen activator inhibitor-1 antigen, and tissue-type plasminogen activator antigen. Associations between CRP and the variables of the insulin resistance syndrome disappeared after controlling for BMI but remained significant for plasminogen activator inhibitor-1 antigen only. The association of CRP with common carotid artery intima-media thickness was weak and limited to ever-smokers. BMI explained 29.7% of the variance of CRP, whereas common carotid artery intima-media thickness explained only 3.7%. The results of this population-based study indicate that adiposity is strongly associated with CRP in healthy, middle-aged women. In this population, BMI accounted for the relationship between CRP and other variables of the insulin resistance syndrome. Further studies should determine whether losing weight ameliorates the inflammatory state

    Development of a prediction model for future risk of radiographic hip osteoarthritis

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    Objective: To develop and validate a prognostic model for incident radiologic hip osteoarthritis (HOA) and determine the value of previously identified predictive factors. Design: We first validated previously reported predictive factors for HOA by performing univariate and multivariate analyses for all predictors in three large prospective cohorts (total sample size of 4548 with 653 incident cases). The prognostic model was developed in 2327 individuals followed for 10 years from the Rotterdam Study-I (RS-I) cohort. External validation of the model was tested on discrimination in two other cohorts: RS-II (n = 1435) and the Cohort Hip and Cohort Knee (CHECK) study (n = 786). Results: From the total number of 28 previously reported predictive factors, we were able to replicate 13 factors, while 15 factors were not significantly predictive in a meta-analysis of the three cohorts. The basic model including the demographic, questionnaire, and clinical examination variables (area under the receiver-operating characteristic curve (AUC) = 0.67) or genetic markers (AUC = 0.55) or urinary C-terminal cross-linked telopeptide of type II collagen (uCTX-II) levels (AUC = 0.67) alone were poor predictors of HOA in all cohorts. Imaging factors showed the highest predictive value for the development of HOA (AUC = 0.74). Addition of imaging variables to the basic model led to substantial improvement in the discriminative ability of the model (AUC = 0.78) compared with uCTX-II (AUC = 0.74) or genetic markers (AUC = 0.68). Applying external validation, similar results were observed in the RS-II and the CHECK cohort. Conclusions: The developed prediction model included demographic, a limited number of questionnaire, and imaging risk factors seems promising for prediction of HOA

    Identification and Characterization of Two Novel Viruses in Ocular Infections in Reindeer

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    A thorough understanding of virus diversity in wildlife provides epidemiological baseline information about pathogens. In this study, eye swab samples were obtained from semi-domesticated reindeer (Rangifer tarandus tarandus) in Norway during an outbreak of infectious eye disease, possibly a very early stage of infectious keratoconjunctivitis (IKC). Large scale molecular virus screening, based on host nucleic acid depletion, sequence-independen

    Sub-terahertz, microwaves and high energy emissions during the December 6, 2006 flare, at 18:40 UT

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    The presence of a solar burst spectral component with flux density increasing with frequency in the sub-terahertz range, spectrally separated from the well-known microwave spectral component, bring new possibilities to explore the flaring physical processes, both observational and theoretical. The solar event of 6 December 2006, starting at about 18:30 UT, exhibited a particularly well-defined double spectral structure, with the sub-THz spectral component detected at 212 and 405 GHz by SST and microwaves (1-18 GHz) observed by the Owens Valley Solar Array (OVSA). Emissions obtained by instruments in satellites are discussed with emphasis to ultra-violet (UV) obtained by the Transition Region And Coronal Explorer (TRACE), soft X-rays from the Geostationary Operational Environmental Satellites (GOES) and X- and gamma-rays from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The sub-THz impulsive component had its closer temporal counterpart only in the higher energy X- and gamma-rays ranges. The spatial positions of the centers of emission at 212 GHz for the first flux enhancement were clearly displaced by more than one arc-minute from positions at the following phases. The observed sub-THz fluxes and burst source plasma parameters were found difficult to be reconciled to a purely thermal emission component. We discuss possible mechanisms to explain the double spectral components at microwaves and in the THz ranges.Comment: Accepted version for publication in Solar Physic

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

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    Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

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    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

    Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

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    The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter
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