93 research outputs found

    Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV

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    The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √s = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT≄20 GeV and pseudorapidities {pipe}η{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}η{pipe}<0. 8) for jets with 60≀pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2≀{pipe}η{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. © 2013 CERN for the benefit of the ATLAS collaboration

    Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

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    The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

    Measurement of the cross-section for b-jets produced in association with a Z boson at root s=7 TeV with the ATLAS detector ATLAS Collaboration

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    A measurement is presented of the inclusive cross-section for b-jet production in association with a Z boson in pp collisions at a centre-of-mass energy of root s = 7 TeV. The analysis uses the data sample collected by the ATLAS experiment in 2010, corresponding to an integrated luminosity of approximately 36 pb(-1). The event selection requires a Z boson decaying into high P-T electrons or muons, and at least one b-jet, identified by its displaced vertex, with transverse momentum p(T) > 25 GeV and rapidity vertical bar y vertical bar < 2.1. After subtraction of background processes, the yield is extracted from the vertex mass distribution of the candidate b-jets. The ratio of this cross-section to the inclusive Z cross-section (the average number of b-jets per Z event) is also measured. Both results are found to be in good agreement with perturbative QCD predictions at next-to-leading order

    Measurement of charged-particle event shape variables in inclusive root(s)=7 TeV proton-proton interactions with the ATLAS detector

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    The measurement of charged-particle event shape variables is presented in inclusive inelastic pp collisions at a center-of-mass energy of 7 TeV using the ATLAS detector at the LHC. The observables studied are the transverse thrust, thrust minor, and transverse sphericity, each defined using the final-state charged particles' momentum components perpendicular to the beam direction. Events with at least six charged particles are selected by a minimum-bias trigger. In addition to the differential distributions, the evolution of each event shape variable as a function of the leading charged-particle transverse momentum, charged-particle multiplicity, and summed transverse momentum is presented. Predictions from several Monte Carlo models show significant deviations from data

    Changes to the Fossil Record of Insects through Fifteen Years of Discovery

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    The first and last occurrences of hexapod families in the fossil record are compiled from publications up to end-2009. The major features of these data are compared with those of previous datasets (1993 and 1994). About a third of families (>400) are new to the fossil record since 1994, over half of the earlier, existing families have experienced changes in their known stratigraphic range and only about ten percent have unchanged ranges. Despite these significant additions to knowledge, the broad pattern of described richness through time remains similar, with described richness increasing steadily through geological history and a shift in dominant taxa, from Palaeoptera and Polyneoptera to Paraneoptera and Holometabola, after the Palaeozoic. However, after detrending, described richness is not well correlated with the earlier datasets, indicating significant changes in shorter-term patterns. There is reduced Palaeozoic richness, peaking at a different time, and a less pronounced Permian decline. A pronounced Triassic peak and decline is shown, and the plateau from the mid Early Cretaceous to the end of the period remains, albeit at substantially higher richness compared to earlier datasets. Origination and extinction rates are broadly similar to before, with a broad decline in both through time but episodic peaks, including end-Permian turnover. Origination more consistently exceeds extinction compared to previous datasets and exceptions are mainly in the Palaeozoic. These changes suggest that some inferences about causal mechanisms in insect macroevolution are likely to differ as well

    Search for the standard model Higgs boson in the diphoton decay channel with 4.9fb -1 of pp collision data at √s=7TeV with atlas

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    A search for the standard model Higgs boson is performed in the diphoton decay channel. The data used correspond to an integrated luminosity of 4.9  fb-1 collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of √s=7  TeV. In the diphoton mass range 110–150 GeV, the largest excess with respect to the background-only hypothesis is observed at 126.5 GeV, with a local significance of 2.8 standard deviations. Taking the look-elsewhere effect into account in the range 110–150 GeV, this significance becomes 1.5 standard deviations. The standard model Higgs boson is excluded at 95% confidence level in the mass ranges of 113–115 GeV and 134.5–136 GeV

    Search for the standard model Higgs boson in the diphoton decay channel with 4.9fb -1 of pp collision data at √s=7TeV with atlas

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    A search for the standard model Higgs boson is performed in the diphoton decay channel. The data used correspond to an integrated luminosity of 4.9  fb-1 collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of √s=7  TeV. In the diphoton mass range 110–150 GeV, the largest excess with respect to the background-only hypothesis is observed at 126.5 GeV, with a local significance of 2.8 standard deviations. Taking the look-elsewhere effect into account in the range 110–150 GeV, this significance becomes 1.5 standard deviations. The standard model Higgs boson is excluded at 95% confidence level in the mass ranges of 113–115 GeV and 134.5–136 GeV

    Drons col·laboratius

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    La robĂČtica col·laborativa Ă©s senzillament robots dissenyats per dur a terme treballs de col·laboraciĂł amb els humans. Els robots col·laboratius o cobots sĂłn cada cop mĂ©s utilitzats a les indĂșstries. La robĂČtica col·laborativa Ă©s un dels Ă mbits d'actualitat en aquests moments. PerĂČ tambĂ© Ă©s un dels mĂ©s interessants en mĂ©s d'un sentit. Com es comuniquen dos drons autĂČnoms que col·laboren per fer una tasca? Com sĂłn aquests missatges que s'envien? Que poden fer que no podrien fer sols? Aquestes sĂłn algunes de les preguntes que ens volem respondre en aquest projecte. En aquest treball es presenta un disseny i implementaciĂł de dos drons terrestres que es comuniquen per col·laborar entre ells per resoldre una tasca.Collaborative robotics is simply robots designed to perform collaborative work with humans. Collaborative robots or cobots are increasingly used in industries. Collaborative robotics is one of the current topics now. But it is also one of the most interesting in more ways than one. How do two autonomous drones that collaborate to perform a task communicate? How are these messages sent? What can they do that they could not do alone? These are some of the questions we want to answer in this project. This work presents a design and implementation of two ground drones that communicate to collaborate with each other to solve a task.La robĂłtica colaborativa es sencillamente robots diseñados para llevar a cabo trabajos de colaboraciĂłn con los humanos. Los robots colaborativos o cobots son cada vez mĂĄs utilizados en las industrias. La robĂłtica colaborativa es uno de los ĂĄmbitos de actualidad. Pero tambiĂ©n es uno de los mĂĄs interesantes en mĂĄs de un sentido. ÂżCĂłmo se comunican drones autĂłnomos que colaboran para hacer una tarea? ÂżCĂłmo son estos mensajes que es envĂ­an? ÂżQuĂ© pueden hacer que no lo podrĂ­an hacer solos? Estas son algunas de las preguntas que queremos responder con este proyecto. En este trabajo se presenta un diseño e implementaciĂłn de dos drones terrestres que se comunican para colaborar entre ellos para resolver una tarea

    Compound effect of EHD and surface roughness in pool boiling and CHF with R-123

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    This article is a post-print version of the fianl published article which may be accessed at the link below.Saturated pool boiling of R-123 at 1 bar, including the critical heat flux (CHF), was enhanced by modifying the surface characteristics and applying a high intensity electrostatic field, the latter termed electrohydrodynamic (and abbreviated EHD) enhancement. The heat flux was varied from very low values in the natural convection regime up to CHF. Experiments were performed with increasing and decreasing heat flux to study boiling hysteresis without and with EHD. Boiling occurred on the sand blasted surface of a cylindrical copper block with embedded electrical heating elements, with standardized surface parameter Pa = 3.5 ÎŒm. The electric field was generated by a potential of 5 kV to 25 kV, applied through a 40 mm diameter circular electrode of ss-304 wire mesh, aperture size 5.1 mm, located at distances of 5 - 60 mm from the surface, with most of the data obtained for 20 mm. The data for the rough surface were compared with earlier data for a smooth surface and indicated a significant increase in the heat transfer rates. EHD produced a further increase in the heat transfer rates, particularly at low heat flux values and near the CHF. Boiling hysteresis was reduced progressively by EHD and eliminated at high field strength.This work was supported by Government of Pakistan under a scholarship programme

    KC 4.1: Rural heritage and urban-rural linkages in the ICOMOS SDGs Policy Guidance

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    This Knowledge CafĂ© aims to provide a discussion platform to contribute to the drafting of a new ICOMOS SDGs Policy Guidance, from the perspective of rural heritage, landscapes and rural-urban linkages. While 50%-plus of global populations are urban dwellers, we tend to forget that the other half dwell in rural places. One of the 7 Priority Actions of the ICOMOS SDGs Working Group in 2018 is the preparation of a consolidated policy statement, as an effective tool for advocacy and communication to wider society and the development world. Based on the need to boost the role of cultural heritage in sustainable development processes, this would be a robust Policy Guidance document, serving to improve the recognition of the role of cultural heritage protection, particularly as defined by SDG 11.4 and the New Urban Agenda. The ICOMOS SDGs Working Group aims to launch this document at the 10th World Urban Forum in 2020 and at the High-Level Political Forum in 2021. The new Policy Guidance aims to emphasize “heritage as a resource, a strategic opportunity”, using the framework of the 3 dimensions of sustainability, economic, social, environmental, and propose adding the 4th dimension of ‘culture’ through an appropriate approach. The document should be based on solid scientific expertise sourced from ICOMOS membership. The Symposium on Rural Heritage: Landscapes and Beyond is a prime opportunity to involve some of this membership, ensuring a diverse and inclusive range of expertise in heritage informs the Policy Guidance. Rural heritage and landscapes, including rural-urban linkages, have great relevance for the intersection of cultural heritage and sustainable development, touching on many SDGs and issues raised in the New Urban Agenda, not to mention the Historic Urban Landscape Recommendation. To cite some examples of this inter-connectedness, the “inter-related categories of continuity and change” addressed during the Symposium, provide the following links: - under ‘Rural Culture’ to SDG 11.4 (change management for tangible rural heritage), SDG 1.5, 2.4, 11.5, 11.b, 13.1 (risk of loss of intangible rural traditions/ practices), SDG 8.9, SDG 12.b (rural cultural tourism), SDG 16.7, 16.a, 17.9, 17.15, 17.17 (identity of people and places); - under ‘Rural economics’ to SDG 1 (poverty eradication), SDG2 (food security), SDG3 (rural agricultural heritage), SDG 8 (improvement of markets and opportunities for rural traditional tools, techniques and rural heritage tourism), SDG 8 (infrastructure, services to small enterprises), SDG 11 (spatial form, territorial policies); - under ‘Rural Environment’ to SDG 6 (water), 13 and 15 (desertification, climate-induced severe weather events, biodiversity, forest management); and - under ‘Rural Society’ to SDG 1 (poverty alleviation) SDG 2 (agriculture), SDG 3.8, 3.c (health services), SDG 16, 17 (bottom-up governance). - Some case studies from ‘Moroccan Rural Heritage’ can be proposed during the session from participants who may have relevant knowledge, to demonstrate these links. The Knowledge CafĂ© will feature two speakers, Ege Yildirim and Patricia O’Donnell, giving the conceptual framework of the session, followed by Ilaria Rosetti presenting the method of open discussion, whereby breakout groups (e.g. 3-4 groups of 5-6) can discuss the links of rural heritage issues to the various 17 Goals and Targets under them, concluding with short reporting from each group, to be compiled and disseminated later by the conveners
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