788 research outputs found

    The Mass-Metallicity relation explored with CALIFA: I. Is there a dependence on the star formation rate?

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    We present the results on the study of the global and local M-Z relation based on the first data available from the CALIFA survey (150 galaxies). This survey provides integral field spectroscopy of the complete optical extent of each galaxy (up to 2-3 effective radii), with enough resolution to separate individual HII regions and/or aggregations. Nearly \sim3000 individual HII regions have been detected. The spectra cover the wavelength range between [OII]3727 and [SII]6731, with a sufficient signal-to-noise to derive the oxygen abundance and star-formation rate associated with each region. In addition, we have computed the integrated and spatially resolved stellar masses (and surface densities), based on SDSS photometric data. We explore the relations between the stellar mass, oxygen abundance and star-formation rate using this dataset. We derive a tight relation between the integrated stellar mass and the gas-phase abundance, with a dispersion smaller than the one already reported in the literature (σΔlog(O/H)=\sigma_{\Delta{\rm log(O/H)}}=0.07 dex). Indeed, this dispersion is only slightly larger than the typical error derived for our oxygen abundances. However, we do not find any secondary relation with the star-formation rate, other than the one induced due to the primary relation of this quantity with the stellar mass. We confirm the result using the \sim3000 individual HII regions, for the corresponding local relations. Our results agree with the scenario in which gas recycling in galaxies, both locally and globally, is much faster than other typical timescales, like that of gas accretion by inflow and/or metal loss due to outflows. In essence, late-type/disk dominated galaxies seem to be in a quasi-steady situation, with a behavior similar to the one expected from an instantaneous recycling/closed-box model.Comment: 19 Pages, 8 figures, Accepted for Publishing in Astronomy and Astrophysics (A&A

    Performance of prototypes for the ALICE electromagnetic calorimeter

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    The performance of prototypes for the ALICE electromagnetic sampling calorimeter has been studied in test beam measurements at FNAL and CERN. A 4×44\times4 array of final design modules showed an energy resolution of about 11% /E(GeV)\sqrt{E(\mathrm{GeV})} \oplus 1.7 % with a uniformity of the response to electrons of 1% and a good linearity in the energy range from 10 to 100 GeV. The electromagnetic shower position resolution was found to be described by 1.5 mm \oplus 5.3 mm /E(GeV)\sqrt{E \mathrm{(GeV)}}. For an electron identification efficiency of 90% a hadron rejection factor of >600>600 was obtained.Comment: 10 pages, 10 figure

    Maternal position during the first stage of labor: a systematic review

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    BACKGROUND: Policy makers and health professionals are progressively using evidence-based rationale to guide their decisions. There has long been controversy regarding which maternal position is more appropriate during the first stage of labor. This problem has been examined often and repeatedly and the optimal recommendation remains unclear. METHODS: This is a systematic review of the effect of maternal position during the first stage of labor. The main question addressed here is: Does encouraging women to adopt an upright position or to ambulate during the first stage of labor reduce the duration of this stage? All randomized controlled trials carried out to assess this effect were taken into consideration in this review. The following electronic databases were accessed to identify studies: MEDLINE, Popline, the Scientific Electronic Library On-line and the Latin American and Caribbean Health Science Information. Citation eligibility was independently assessed by two reviewers. The methodological quality of each trial was also evaluated independently by two reviewers and a trial under consideration was included only when consensus had been attained. Allocation concealment and screening for the occurrence of attrition, performance and detection biases were considered when studies were appraised. The decision whether to perform data pooling was based on the clinical similarity of studies. RESULTS: The search strategy resulted in 260 citations, of which 18 were assessed in full-text. Nine eligible randomized controlled trials were included in the systematic review. Randomization methods were not fully described in eight studies. The allocation concealment was considered adequate in four studies and unclear in five. The investigators pooled the data from seven studies in which the length of the first stage of labor and results were in favor of the intervention, but the high level of heterogeneity (I(2 )= 88.4%) impaired the meaning of this finding. The intervention did not affect other outcomes studied (mode of delivery, use of analgesia, labor augmentation and condition of the child at birth). CONCLUSION: Adoption of the upright position or ambulation during first stage of labor may be safe, but considering the available evidence and its consistency, it cannot be recommended as an effective intervention to reduce duration of the first stage of labor

    TRY plant trait database - enhanced coverage and open access

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    Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

    Standalone vertex finding in the ATLAS muon spectrometer

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    A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

    Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

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    Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

    Measurement of the top quark-pair production cross section with ATLAS in pp collisions at \sqrt{s}=7\TeV

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    A measurement of the production cross-section for top quark pairs(\ttbar) in pppp collisions at \sqrt{s}=7 \TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron ee or muon μ\mu) with large missing transverse energy and at least four jets, and dilepton (eeee, μμ\mu\mu or eμe\mu) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-\ttbar Standard Model processes are estimated using data-driven methods and determined to be 12.2±3.912.2 \pm 3.9 events and 2.5±0.62.5 \pm 0.6 events, respectively. The kinematic properties of the selected events are consistent with SM \ttbar production. The inclusive top quark pair production cross-section is measured to be \sigmattbar=145 \pm 31 ^{+42}_{-27} pb where the first uncertainty is statistical and the second systematic. The measurement agrees with perturbative QCD calculations.Comment: 30 pages plus author list (50 pages total), 9 figures, 11 tables, CERN-PH number and final journal adde

    Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

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    A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction

    Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb−1 of √s=7 TeV proton-proton collisions

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    Results are presented of a search for new particles decaying to large numbers of jets in association with missing transverse momentum, using 4.7 fb−1 of pp collision data at s√=7TeV collected by the ATLAS experiment at the Large Hadron Collider in 2011. The event selection requires missing transverse momentum, no isolated electrons or muons, and from ≥6 to ≥9 jets. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of a MSUGRA/CMSSM supersymmetric model, where, for large universal scalar mass m 0, gluino masses smaller than 840 GeV are excluded at the 95% confidence level, extending previously published limits. Within a simplified model containing only a gluino octet and a neutralino, gluino masses smaller than 870 GeV are similarly excluded for neutralino masses below 100 GeV

    Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report Volume 2: The Physics Program for DUNE at LBNF

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    The Physics Program for the Deep Underground Neutrino Experiment (DUNE) at the Fermilab Long-Baseline Neutrino Facility (LBNF) is described
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