45 research outputs found

    Head-Up Displays and Distraction Potential

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    DTNH22-11-D-00236Task Order 0019Head-up displays (HUDs) present opportunities and challenges for mitigating driver distraction. HUDs may improve safety by reducing the time required to view driving-related information relative to a traditional head-down display (HDD). However, because the HUD is in the driver\u2019s field of view, drivers may fixate on it and fail to perceive events in the environment. This study used 48 participants in the dataset and investigated driver use of a HUD, an HDD, and an aftermarket, phone-based display by measuring visual behavior during public road driving. Additionally, participants completed a task that used the displays to assess reactions to a surprise event on the Virginia Smart Road. Results showed participants had faster glances to a HUD when drivers were asked to read driving information; however, drivers were more likely to glance at the HUD than other displays while driving. While driving on a closed test track, drivers were asked to fixate on their assigned display (HDD, HUD, or aftermarket display) during a surprise event (an object dropped in the road). Reactions with the HUD were no faster than the HDD or aftermarket display while fixating on displays

    The Baryon Oscillation Spectroscopic Survey of SDSS-III

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    The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large scale structure. BOSS uses 1.5 million luminous galaxies as faint as i=19.9 over 10,000 square degrees to measure BAO to redshifts z<0.7. Observations of neutral hydrogen in the Lyman alpha forest in more than 150,000 quasar spectra (g<22) will constrain BAO over the redshift range 2.15<z<3.5. Early results from BOSS include the first detection of the large-scale three-dimensional clustering of the Lyman alpha forest and a strong detection from the Data Release 9 data set of the BAO in the clustering of massive galaxies at an effective redshift z = 0.57. We project that BOSS will yield measurements of the angular diameter distance D_A to an accuracy of 1.0% at redshifts z=0.3 and z=0.57 and measurements of H(z) to 1.8% and 1.7% at the same redshifts. Forecasts for Lyman alpha forest constraints predict a measurement of an overall dilation factor that scales the highly degenerate D_A(z) and H^{-1}(z) parameters to an accuracy of 1.9% at z~2.5 when the survey is complete. Here, we provide an overview of the selection of spectroscopic targets, planning of observations, and analysis of data and data quality of BOSS.Comment: 49 pages, 16 figures, accepted by A

    Marine mammal hotspots across the circumpolar Arctic

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    Aim: Identify hotspots and areas of high species richness for Arctic marine mammals. Location: Circumpolar Arctic. Methods: A total of 2115 biologging devices were deployed on marine mammals from 13 species in the Arctic from 2005 to 2019. Getis-Ord Gi* hotspots were calculated based on the number of individuals in grid cells for each species and for phyloge-netic groups (nine pinnipeds, three cetaceans, all species) and areas with high spe-cies richness were identified for summer (Jun-Nov), winter (Dec-May) and the entire year. Seasonal habitat differences among species’ hotspots were investigated using Principal Component Analysis. Results: Hotspots and areas with high species richness occurred within the Arctic continental-shelf seas and within the marginal ice zone, particularly in the “Arctic gateways” of the north Atlantic and Pacific oceans. Summer hotspots were generally found further north than winter hotspots, but there were exceptions to this pattern, including bowhead whales in the Greenland-Barents Seas and species with coastal distributions in Svalbard, Norway and East Greenland. Areas with high species rich-ness generally overlapped high-density hotspots. Large regional and seasonal dif-ferences in habitat features of hotspots were found among species but also within species from different regions. Gap analysis (discrepancy between hotspots and IUCN ranges) identified species and regions where more research is required. Main conclusions: This study identified important areas (and habitat types) for Arctic marine mammals using available biotelemetry data. The results herein serve as a benchmark to measure future distributional shifts. Expanded monitoring and teleme-try studies are needed on Arctic species to understand the impacts of climate change and concomitant ecosystem changes (synergistic effects of multiple stressors). While efforts should be made to fill knowledge gaps, including regional gaps and more com-plete sex and age coverage, hotspots identified herein can inform management ef-forts to mitigate the impacts of human activities and ecological changes, including creation of protected areas

    The Baryon Oscillation Spectroscopic Survey of SDSS-III

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    The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large-scale structure. BOSS uses 1.5 million luminous galaxies as faint as i = 19.9 over 10,000 deg(2) to measure BAO to redshifts z < 0.7. Observations of neutral hydrogen in the Ly alpha forest in more than 150,000 quasar spectra (g < 22) will constrain BAO over the redshift range 2.15 < z < 3.5. Early results from BOSS include the first detection of the large-scale three-dimensional clustering of the Ly alpha forest and a strong detection from the Data Release 9 data set of the BAO in the clustering of massive galaxies at an effective redshift z = 0.57. We project that BOSS will yield measurements of the angular diameter distance d(A) to an accuracy of 1.0% at redshifts z = 0.3 and z = 0.57 and measurements of H(z) to 1.8% and 1.7% at the same redshifts. Forecasts for Ly alpha forest constraints predict a measurement of an overall dilation factor that scales the highly degenerate D-A(z) and H-1(z) parameters to an accuracy of 1.9% at z similar to 2.5 when the survey is complete. Here, we provide an overview of the selection of spectroscopic targets, planning of observations, and analysis of data and data quality of BOSS

    Study of the spin and parity of the Higgs boson in diboson decays with the ATLAS detector

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    Studies of the spin, parity and tensor couplings of the Higgs boson in the H→ZZ∗→4ℓ, H→WW∗→eνμν and H→γγ decay processes at the LHC are presented. The investigations are based on 25fb−1 of pp collision data collected by the ATLAS experiment at √s=7 TeV and √s=8 TeV. The Standard Model (SM) Higgs boson hypothesis, corresponding to the quantum numbers JP=0+, is tested against several alternative spin scenarios, including non-SM spin-0 and spin-2 models with universal and non-universal couplings to fermions and vector bosons. All tested alternative models are excluded in favour of the SM Higgs boson hypothesis at more than 99.9 % confidence level. Using the H → ZZ∗ → 4ℓ and H → WW∗ → eνμν decays, the tensor structure of the interaction between the spin-0 boson and the SM vector bosons is also investigated. The observed distributions of variables sensitive to the non-SM tensor couplings are compatible with the SM predictions and constraints on the non-SM couplings are derived

    Search for flavour-changing neutral current top-quark decays to qZ in pp collision data collected with the ATLAS detector at √ s =8 TeV

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    A search for flavour-changing neutral current decays of a top quark to an uptype quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to bb¯, is presented. The analysis searches for top quark pair events in which one top quark decays to Wb, with the W boson decaying leptonically, and the other top quark decays to Hq. The search is based on pp collisions at √s=8 TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and uses an integrated luminosity of 20.3 fb−1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon and at least four jets. The search exploits the high multiplicity of b-quark jets characteristic of signal events, and employs a likelihood discriminant that uses the kinematic differences between the signal and the background, which is dominated by tt¯→WbWb decays. No significant excess of events above the background expectation is found, and observed (expected) 95% CL upper limits of 0.56% (0.42%) and 0.61% (0.64%) are derived for the t → Hc and t → Hu branching ratios respectively. The combination of this search with other ATLAS searches in the H → γγ and H → WW*, ττ decay modes significantly improves the sensitivity, yielding observed (expected) 95% CL upper limits on the t → Hc and t → Hu branching ratios of 0.46% (0.25%) and 0.45% (0.29%) respectively. The corresponding combined observed (expected) upper limits on the |λtcH| and |λtuH| couplings are 0.13 (0.10) and 0.13 (0.10) respectively. These are the most restrictive direct bounds on tqH interactions measured so far

    Search for top quark decays t -> qH,with H -> gamma gamma, in root s=13 TeV pp collisions using the ATLAS detector

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    This article presents a search for flavour-changing neutral currents in the decay of a top quark into an up-type (q = c, u) quark and a Higgs boson, where the Higgs boson decays into two photons. The proton-proton collision data set analysed amounts to 36.1 fb−1 at √ s = 13 TeV collected by the ATLAS experiment at the LHC. Top quark pair events are searched for, where one top quark decays into qH and the other decays into bW. Both the hadronic and leptonic decay modes of the W boson are used. No significant excess is observed and an upper limit is set on the t → cH branching ratio of 2.2 × 10−3 at the 95% confidence level, while the expected limit in the absence of signal is 1.6 × 10−3 . The corresponding limit on the tcH coupling is 0.090 at the 95% confidence level. The observed upper limit on the t → uH branching ratio is 2.4 × 10−3.

    Modeling Connectivity of Black Bears in a Desert Sky Island Archipelago

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    Landscape features such as rivers, mountains, desert basins, roads, and impermeable man-made structures may influence dispersal and gene flow among populations, thereby creating spatial structure across the landscape. In the US–Mexico borderland, urbanization and construction of the border fence have the potential to increase genetic subdivision and vulnerability to isolation in large mammal populations by bisecting movement corridors that have enabled dispersal between adjacent Sky Island mountain ranges. We examined genetic variation in black bears (Ursus americanus) from three regions in central and southern Arizona, US, to assess genetic and landscape connectivity in the US–Mexico border Sky Islands. We found that the three regions grouped into two subpopulations: the east-central subpopulation comprised of individuals sampled in the central highland and high desert regions, and the border subpopulation comprised of individuals sampled in the southern Sky Islands. Occupancy for the border subpopulation of black bears was influenced by cover type and distance to water, and occupancy-based corridor models identified 14 potential corridors connecting border Sky Island habitat cores with the east-central subpopulation. Biological quality of corridors, defined as length:width ratio and proportions of suitable habitat within corridors, declined with Sky Island dispersion. Our results show that black bears in the border subpopulation are moderately isolated from the east-central subpopulation, the main population segment of black bears in Arizona, and that connectivity for border bears may be vulnerable to anthropogenic activities, such as those associated with urbanization and trans-border security
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