1,682 research outputs found

    Groups of Galaxies in AEGIS: The 200 ksec Chandra Extended X-ray Source catalogue

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    We present the discovery of seven X-ray emitting groups of galaxies selected as extended X-ray sources in the 200 ksec Chandra coverage of the All-wavelength Extended Groth Strip International Survey (AEGIS). In addition, we report on AGN activity associated to these systems. Using the DEEP2 Galaxy Redshift Survey coverage, we identify optical counterparts and determine velocity dispersions. In particular, we find three massive high-redshift groups at z>0.7, one of which is at z=1.13, the first X-ray detections of spectroscopically selected DEEP2 groups. We also present a first look at the the L_X-T, L_X-sigma, and sigma-T scaling relations for high-redshift massive groups. We find that the properties of these X-ray selected systems agree well with the scaling relations of similar systems at low redshift, although there are X-ray undetected groups in the DEEP2 catalogue with similar velocity dispersions. The other three X-ray groups with identified redshifts are associated with lower mass groups at z~0.07 and together form part of a large structure or "supergroup" in the southern portion of the AEGIS field. All of the low-redshift systems are centred on massive elliptical galaxies, and all of the high-redshift groups have likely central galaxies or galaxy pairs. All of the central group galaxies host X-ray point sources, radio sources, and/or show optical AGN emission. Particularly interesting examples of central AGN activity include a bent-double radio source plus X-ray point source at the center of a group at z=0.74, extended radio and double X-ray point sources associated to the central galaxy in the lowest-redshift group at z=0.066, and a bright green valley galaxy (part of a pair) in the z=1.13 group which shows optical AGN emission lines.Comment: accepted to MNRAS, 15 pages, 11 figures, for version with full resolution figures see http://www.ucolick.org/~tesla/aegis_groups.ps.g

    The impact of trammel nets as an MPA soft bottom monitoring method

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    With the global increase of marine protected area (MPA) implementation, the need for monitoring and the evaluation of their effectiveness becomes ever more important. Currently there is a severe lack of information about the protection effects of soft-substrate ecosystems. While many different methods have been established for the monitoring of hard-substrate ecosystems, most of these minimally invasive methods prove ineffective for soft- bottom habitats. Information and quantification of the impact of monitoring methods is needed to provide decision makers with the necessary knowledge to choose appropriate and feasible monitoring methods. In this study we quantify the impact of experimental trammel net fishing as a monitoring method of the soft-substrate demersal fish community using the ArrĂĄbida MPA (Portugal) as a case study. Over the 14 biannual sampling campaigns (between 2010 and 2019) 21,873 individuals and 5.61 tonnes of fish were caught. The gear is highly effective with an average catch per unit effort higher than reported for commercial fisheries in adjacent areas. When excluding the pelagic species, mortality rates are 41.2% and 30.4% in numbers and biomass, respectively. Most of the dead individuals belong to small, non-protected species with relatively little commercial value while MPA conservation target groups such as Soleidae and Rajidae have high survival rates. Due to its low size- and species-selectivity and the high survival rate of protected valuable species, the trammel net experimental fishing proved to be an effective monitoring method for soft-substrate demersal fish communities. Given their relatively low impact on the local ecosystem experimental trammel nets are a good alternative for areas where nonextractive methods are not effective. Nevertheless, quantification of the impact of other monitoring methods is necessary to enable the determination of the methods with the lowest mortality and impact for future softsubstrate MPA monitoring.LIFE06 NAT/P/000192 FCT: UID/Multi/04326/2020; DL 57/2016/CP1361/CT0036; European Maritime and Fisheries Fund INFORBIOMARES: POSEUR-03-2215-FC-000047info:eu-repo/semantics/publishedVersio

    Measurement of Dijet Angular Distributions and Search for Quark Compositeness

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    We have measured the dijet angular distribution in s\sqrt{s}=1.8 TeV ppˉp\bar{p} collisions using the D0 detector. Order αs3\alpha^{3}_{s} QCD predictions are in good agreement with the data. At 95% confidence the data exclude models of quark compositeness in which the contact interaction scale is below 2 TeV.Comment: 11 pages, Latex, 3 postscript figure

    Differential Production Cross Section of Z Bosons as a Function of Transverse Momentum at sqrt{s}=1.8 TeV

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    We present a measurement of the transverse momentum distribution of Z bosons produced in ppbar collisions at sqrt{s}=1.8 TeV using data collected by the D0 experiment at the Fermilab Tevatron Collider during 1994--1996. We find good agreement between our data and a current resummation calculation. We also use our data to extract values of the non-perturbative parameters for a particular version of the resummation formalism, obtaining significantly more precise values than previous determinations.Comment: 10 pages, 2 figures, submitted to Phys. Rev. Letters v2 has margin error correcte

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+→Ό+ÎœW^+ \rightarrow \mu^+\nu and W−→Ό−ΜW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

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    Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

    Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

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    A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

    Literature and Education in the Long 1930s

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    COVID-19: Rapid antigen detection for SARS-CoV-2 by lateral flow assay: A national systematic evaluation of sensitivity and specificity for mass-testing

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    Background Lateral flow device (LFD) viral antigen immunoassays have been developed around the world as diagnostic tests for SARS-CoV-2 infection. They have been proposed to deliver an infrastructure-light, cost-economical solution giving results within half an hour. Methods LFDs were initially reviewed by a Department of Health and Social Care team, part of the UK government, from which 64 were selected for further evaluation from 1st August to 15th December 2020. Standardised laboratory evaluations, and for those that met the published criteria, field testing in the Falcon-C19 research study and UK pilots were performed (UK COVID-19 testing centres, hospital, schools, armed forces). Findings 4/64 LFDs so far have desirable performance characteristics (orient Gene, Deepblue, Abbott and Innova SARS-CoV-2 Antigen Rapid Qualitative Test). All these LFDs have a viral antigen detection of >90% at 100,000 RNA copies/ml. 8951 Innova LFD tests were performed with a kit failure rate of 5.6% (502/8951, 95% CI: 5.1–6.1), false positive rate of 0.32% (22/6954, 95% CI: 0.20–0.48). Viral antigen detection/sensitivity across the sampling cohort when performed by laboratory scientists was 78.8% (156/198, 95% CI 72.4–84.3). Interpretation Our results suggest LFDs have promising performance characteristics for mass population testing and can be used to identify infectious positive individuals. The Innova LFD shows good viral antigen detection/sensitivity with excellent specificity, although kit failure rates and the impact of training are potential issues. These results support the expanded evaluation of LFDs, and assessment of greater access to testing on COVID-19 transmission. Funding Department of Health and Social Care. University of Oxford. Public Health England Porton Down, Manchester University NHS Foundation Trust, National Institute of Health Research

    Comparing Notes: Recording and Criticism

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    This chapter charts the ways in which recording has changed the nature of music criticism. It both provides an overview of the history of recording and music criticism, from the advent of Edison’s Phonograph to the present day, and examines the issues arising from this new technology and the consequent transformation of critical thought and practice
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