26 research outputs found

    Variation in prey delivered to common Black-Hawk (Buteogallus anthracinus) nests in Arizona drainage basins

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    Understanding how raptor diets vary across local and regional scales can be important when human actions have the potential to alter prey abundances. We combined data on prey delivered to 16 Common Black-Hawk (Buteogallus anthracinus) nests in three tributaries of the Verde River, Arizona, in 2008 and 2009 with similar data reported previously (1994) for three other Arizona drainage basins to better understand variation in diet composition within and across drainage basins. Within the three drainage basins studied in 2008 and 2009, nests clustered into two groups: those along Fossil Creek, where fish and amphibians were common, and those in Wet Beaver and Oak Creek drainage basins, where reptiles and nonnative crayfish were more abundant. When data from all six drainage basins were combined, drainage basins again clustered into two groups, with prey deliveries in one cluster dominated by fish and amphibians and in the other cluster by reptiles. These results confirm the opportunistic nature of prey use by Common Black-Hawks and highlight the variation in diet that can occur both within and among drainage basins. Management targeting the eradication of nonnative crayfish or the reintroduction of native amphibians and fish could alter prey availability for this raptor species

    Muon reconstruction and identification efficiency in ATLAS using the full Run 2 pp collision data set at \sqrt{s}=13 TeV

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    This article documents the muon reconstruction and identification efficiency obtained by the ATLAS experiment for 139 \hbox {fb}^{-1} of pp collision data at \sqrt{s}=13 TeV collected between 2015 and 2018 during Run 2 of the LHC. The increased instantaneous luminosity delivered by the LHC over this period required a reoptimisation of the criteria for the identification of prompt muons. Improved and newly developed algorithms were deployed to preserve high muon identification efficiency with a low misidentification rate and good momentum resolution. The availability of large samples of Z\rightarrow \mu \mu and J/\psi \rightarrow \mu \mu decays, and the minimisation of systematic uncertainties, allows the efficiencies of criteria for muon identification, primary vertex association, and isolation to be measured with an accuracy at the per-mille level in the bulk of the phase space, and up to the percent level in complex kinematic configurations. Excellent performance is achieved over a range of transverse momenta from 3 GeV to several hundred GeV, and across the full muon detector acceptance of |\eta |<2.7

    The ATLAS inner detector trigger performance in pp collisions at 13 TeV during LHC Run 2

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    The design and performance of the inner detector trigger for the high level trigger of the ATLAS experiment at the Large Hadron Collider during the 2016-2018 data taking period is discussed. In 2016, 2017, and 2018 the ATLAS detector recorded 35.6 fb(-1), 46.9 fb(-1), and 60.6 fb(-1) respectively of proton-proton collision data at a centre-of-mass energy of 13TeV. In order to deal with the very high interaction multiplicities per bunch crossing expected with the 13TeV collisions the inner detector trigger was redesigned during the long shutdown of the Large Hadron Collider from 2013 until 2015. An overview of these developments is provided and the performance of the tracking in the trigger for the muon, electron, tau and b-jet signatures is discussed. The high performance of the inner detector trigger with these extreme interaction multiplicities demonstrates how the inner detector tracking continues to lie at the heart of the trigger performance and is essential in enabling the ATLAS physics programme

    Observation of electroweak production of two jets in association with an isolated photon and missing transverse momentum, and search for a Higgs boson decaying into invisible particles at 13 TeV with the ATLAS detector

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    This paper presents the measurement of the electroweak production of two jets in association with a ZγZ\gamma pair with the ZZ boson decaying into two neutrinos. It also presents the search for invisible or partially invisible decays of a Higgs boson with a mass of 125 GeV produced through vector-boson fusion with a photon in the final state. These results use data from LHC proton-proton collisions at s\sqrt{s} = 13 TeV collected with the ATLAS detector corresponding to an integrated luminosity of 139 fb1^{-1}. The event signature, shared by all benchmark processes considered for measurements and searches, is characterized by a significant amount of unbalanced transverse momentum and a photon in the final state, in addition to a pair of forward jets. For electroweak production of ZγZ\gamma in association with two jets, the background-only hypothesis is rejected with an observed (expected) significance of 5.2 (5.1) standard deviations. The measured fiducial cross-section for this process is 1.31±\pm0.29 fb. Observed (expected) upper limit of 0.37 (0.34) at 95% confidence level is set on the branching ratio of a 125 GeV Higgs boson to invisible particles, assuming the Standard Model production cross-section. The signature is also interpreted in the context of decays of a Higgs boson to a photon and a dark photon. An observed (expected) 95% CL upper limit on the branching ratio for this decay is set at 0.018 (0.017), assuming the 125 GeV Standard Model Higgs boson production cross-section

    Transcranial direct current stimulation (tDCS) to dorsolateral prefrontal cortex influences perceived pleasantness of food

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    The ability to regulate the intake of unhealthy foods is critical in modern, calorie dense food environments. Frontal areas of the brain, such as the dorsolateral prefrontal cortex (DLPFC), are thought to play a central role in cognitive control and emotional regulation. Therefore, increasing activity in the DLPFC may enhance these functions which could improve the ability to reappraise and resist consuming highly palatable but unhealthy foods. One technique for modifying brain activity is transcranial direct current stimulation (tDCS), a non-invasive technique for modulating neuronal excitability that can influence performance on a range of cognitive tasks. We tested whether anodal tDCS targeting the right DLPFC would influence how people perceived highly palatable foods. In the present study, 98 participants were randomly assigned to receive a single session of active tDCS (2.0 mA) or sham stimulation. While receiving active or sham stimulation, participants viewed images of highly palatable foods and reported how pleasant it would be to eat each food (liking) and how strong their urge was to eat each food (wanting). We found that participants who received active versus sham tDCS stimulation perceived food as less pleasant, but there was no difference in how strong their urge was to eat the foods. Our findings suggest that modulating excitability in the DLPFC influences liking but not wanting of highly palatable foods. Non-invasive brain stimulation might be a useful technique for influencing the hedonic experience of eating but more work is needed to understand when and how it influences food cravings

    Strategies for Selecting Routes through Real-World Environments: Relative Topography, Initial Route Straightness, and Cardinal Direction

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    <div><p>Previous research has demonstrated that route planners use several reliable strategies for selecting between alternate routes. Strategies include selecting straight rather than winding routes leaving an origin, selecting generally south- rather than north-going routes, and selecting routes that avoid traversal of complex topography. The contribution of this paper is characterizing the relative influence and potential interactions of these strategies. We also examine whether individual differences would predict any strategy reliance. Results showed evidence for independent and additive influences of all three strategies, with a strong influence of topography and initial segment straightness, and relatively weak influence of cardinal direction. Additively, routes were also disproportionately selected when they traversed relatively flat regions, had relatively straight initial segments, and went generally south rather than north. Two individual differences, extraversion and sense of direction, predicted the extent of some effects. Under real-world conditions navigators indeed consider a route’s initial straightness, cardinal direction, and topography, but these cues differ in relative influence and vary in their application across individuals.</p></div

    An example trial demonstrating a qualitatively dense click distribution toward the end of an initially straight segment.

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    <p>Blue and red markers indicate a click scored as southern and northern route selections, respectively. Black markers indicate a click outside of the 50-px scoring threshold.</p
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