2,027 research outputs found

    Blood Parasite Infection Differentially Relates to Carotenoid-Based Plumage and Bill Color in the American Goldfinch

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    Male and female American goldfinches (Spinus tristis) express condition-dependent carotenoid-based plumage and bill coloration. Plumage color is relatively static, as pigments incorporated into feathers during the spring molt cannot be mobilized thereafter. In contrast, bill color is dynamic, reflecting changes in condition over short time periods. Previous studies have shown that male and female ornaments, though similar in expression, are differentially related to measures of immunocompetence, suggesting that the relationship between ornamentation and parasite infection may differ between the sexes. In this study, we evaluate the relationship between condition-dependent ornamentation (plumage and bill color) and blood parasite infection in male and female American goldfinches. We captured goldfinches after completion of the pre-alternate molt and prior to the onset of nesting and assessed prevalence of Trypanosoma parasites via blood smears. Plumage color strongly predicted trypanosome infection: Birds with more colorful plumage were less likely to present infections. In contrast, we detected no relationship between infection and bill color, which in other studies has been shown to dynamically reflect current condition. Sex did not affect the relationship between infection status and either ornament. Together, these results suggest that physiological pathways linking carotenoid ornamentation and infection may vary even within a single species

    Inter-annual decrease in pulse rate and peak frequency of Southeast Pacific blue whale song types

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    The decrease in the frequency of two southeast Pacific blue whale song types was examined over decades, usingacoustic data from several different sources ranging between the Equator and Chilean Patagonia. The pulse rate ofthe song units as well as their peak frequency were measured using two different methods (summed auto-correlationand Fourier transform). The sources of error associated with each measurement were assessed. There was a lineardecline in both parameters for the more common song type (southeast Pacific song type n ◩ 2). An abbreviated analysisalso showed a frequency decline in the scarcer southeast Pacific song type n ◩ 1 between 1970 to 2014, revealing thatboth song types are declining at similar rates. We discussed the use of measuring both pulse rate and peak frequencyto examine the frequency decline. Finally, a comparison of the rates of frequency decline with other song typesreported in the literature is presented.La dĂ©croissance en frĂ©quence des deux chants de baleine bleue de l'ocĂ©an pacifique sud est est examinĂ© sur plusieurs dĂ©cennies en utilisant comme source des donnĂ©es acoustiques de l'Equateur Ă  la Patagonie chilienne. La frĂ©quence de pulsation et la frĂ©quence pic des signaux sont mesurĂ©s en utilisant deux mĂ©thodes distinctes (auto-corrĂ©lation sommĂ©e et transformĂ©e de Fourier rapide). Les sources d'erreur associĂ©es Ă  chaque mesure sont estimĂ©es. Il y a un dĂ©clin linĂ©aire de ces deux frĂ©quences pour le chant le plus commun de cette zone (chant du Pacifique Sud Est n°2, SEP2). Un analyse plus rapide montre aussi une baisse linĂ©aire, entre 1970 et 2014, de la frĂ©quence du chant SEP1, plus rarement enregistrĂ© dans cette zone. Ces deux baisses ont des amplitudes similaires. L'intĂ©rĂȘt de mesurer la frĂ©quence de pulsation et la frĂ©quence pic de façon concomitante est estimĂ©. Enfin, une comparaison globale des dĂ©clins en frĂ©quence de tous les types de chants de baleines bleues est fournie

    Pitch- and spectral-based dynamic time warping methods for comparing field recordings of harmonic avian vocalizations

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    Quantitative measures of acoustic similarity can reveal patterns of shared vocal behavior in social species. Many methods for computing similarity have been developed, but their performance has not been extensively characterized in noisy environments and with vocalizations characterized by complex frequency modulations. This paper describes methods of bioacoustic comparison based on dynamic time warping (DTW) of the fundamental frequency or spectrogram. Fundamental frequency is estimated using a Bayesian particle filter adaptation of harmonic template matching. The methods were tested on field recordings of flight calls from superb starlings, Lamprotornis superbus, for how well they could separate distinct categories of call elements (motifs). The fundamental-frequency-based method performed best, but the spectrogram-based method was less sensitive to noise. Both DTW methods provided better separation of categories than spectrographic cross correlation, likely due to substantial variability in the duration of superb starling flight call motifs

    Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

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    The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

    Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

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    The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

    Standalone vertex ïŹnding 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 Îł, H → Z Z∗ →4l and H →W W∗ →lÎœlÎœ. 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 ïŹts 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
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