470 research outputs found

    Syndrome of intraabdominal hypertension: pathophysiological aspects and surgical problems

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    Syndrome of intraabdominal hypertension: pathophysiological aspects and surgical problem

    ФОТОЛЮМИНЕСЦЕНЦИЯ В ВИДИМОЙ ОБЛАСТИ СПЕКТРА АКТИВИРОВАННОГО ТРЕХВАЛЕНТНЫМИ ИОНАМИ ПРАЗЕОДИМА ТИОГАЛЛАТА КАЛЬЦИЯ В ИНТЕРВАЛЕ ТЕМПЕРАТУР 10–300 К

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    The photoluminescence (PL) of the chalcogenide semiconductor compound CaGa2S4:Pr3+ was studied in the temperature range 10–300 K under nanosecond pulsed laser excitation at 456 nm. The PL spectrum consists of a number of intense lines at 494, 631, 654 and 741 nm, formed by electronic transitions in praseodymium ions from 3P0 to 3H4, 3H6, 3F2 and 3F4 levels, respectively. It was found that the rise in the concentration of praseodymium ions in CaGa2S4:Pr3+ from 3 to 7 at. % resulted in a double increase of the PL intensity. Temperature quenching only by 50 and 75 % of the PL intensity of CaGa2S4:Pr3+ with 7 and 3 at. % Pr3+ ions concentration, respectively, was obtained in the range 10–300 K. It is shown that at 10 K the decay time constants of the most intense lines of the PL are between 3.9–4.8 μs. The decrease of the PL decay time constants by less than 0.1 μs with increasing the temperature up to 300 K and the appearance of a fast component with a duration constant of about 2.15–1.1 μs in the temperature range 220–300 K were obtained.Изучена фотолюминесценция (ФЛ) халькогенидного полупроводникового соединения CaGa2S4:Pr3+ в интервале температур 10–300 К при возбуждении лазерными импульсами наносекундной длительности на длине волны 456 нм. Спектр ФЛ состоит из серии интенсивных линий на 494, 631, 654 и 741 нм, обусловленных электронными переходами в ионах празеодима с уровня 3Р0 на 3H4, 3H6, 3F2 и 3F4 соответственно. Установлено, что повышение концентрации ионов празеодима в CaGa2S4 с 3 до 7 ат. % приводит к двукратному возрастанию интегральной интенсивности ФЛ. Температурное тушение ФЛ соединения CaGa2S4:Pr3+ в диапазоне 10–300 К составило всего лишь 50 и 75 % для 7 и 3 ат. % празеодима соответственно. Установлено, что при 10 К временные постоянные затухания наиболее интенсивных линий ФЛ находятся в интервале τe = 3,5–4,5 мкс с незначительной по вкладу быстрой компонентой длительностью около 1 мкс при 300 К. С повышением температуры от 10 до 300 К наблюдается сокращение времен затухания не более чем на 0,1 мкс и появление в кинетиках затухания ФЛ быстрой компоненты длительностью от 2,15 до 1,1 мкс в интервале от 220 до 300 К

    Differential cross-section measurements for the electroweak production of dijets in association with a Z boson in proton–proton collisions at ATLAS

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    Differential cross-section measurements are presented for the electroweak production of two jets in association with a Z boson. These measurements are sensitive to the vector-boson fusion production mechanism and provide a fundamental test of the gauge structure of the Standard Model. The analysis is performed using proton–proton collision data collected by ATLAS at s=13TeVs=13 TeV\sqrt{s}=13\ \hbox {TeV} and with an integrated luminosity of 139fb-1139 fb1139\ \hbox {fb}^{-1}. The differential cross-sections are measured in the Z→ℓ+ℓ-Z+Z\rightarrow \ell ^+\ell ^- decay channel (ℓ=e,μ=e,μ\ell =e,\mu ) as a function of four observables: the dijet invariant mass, the rapidity interval spanned by the two jets, the signed azimuthal angle between the two jets, and the transverse momentum of the dilepton pair. The data are corrected for the effects of detector inefficiency and resolution and are sufficiently precise to distinguish between different state-of-the-art theoretical predictions calculated using Powheg+Pythia8, Herwig7+Vbfnlo and Sherpa 2.2. The differential cross-sections are used to search for anomalous weak-boson self-interactions using a dimension-six effective field theory. The measurement of the signed azimuthal angle between the two jets is found to be particularly sensitive to the interference between the Standard Model and dimension-six scattering amplitudes and provides a direct test of charge-conjugation and parity invariance in the weak-boson self-interactions

    Measurement of the charge asymmetry in top-quark pair production in association with a photon with the ATLAS experiment

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    A measurement of the charge asymmetry in top-quark pair (tt ̄) production in association with a photon is presented. The measurement is performed in the single-lepton tt ̄ decay channel using proton–proton collision data collected with the ATLAS detector at the Large Hadron Collider at CERN at a centre-of-mass-energy of 13 TeV during the years 2015–2018, corresponding to an integrated luminosity of 139 fb−1. The charge asymmetry is obtained from the distribution of the difference of the absolute rapidities of the top quark and antiquark using a profile likelihood unfolding approach. It is measured to be AC=−0.003±0.029 in agreement with the Standard Model expectation

    Search for heavy resonances decaying into a pair of Z bosons in the ℓ + ℓ - ℓ ′ + ℓ ′ - and ℓ + ℓ - ν ν ¯ final states using 139 fb - 1 of proton–proton collisions at s = 13 TeV with the ATLAS detector

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    Abstract: A search for heavy resonances decaying into a pair of Z bosons leading to ℓ+ℓ-ℓ′+ℓ′- and ℓ+ℓ-νν¯ final states, where ℓ stands for either an electron or a muon, is presented. The search uses proton–proton collision data at a centre-of-mass energy of 13 TeV collected from 2015 to 2018 that corresponds to the integrated luminosity of 139 fb-1 recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. Different mass ranges spanning 200 GeV to 2000 GeV for the hypothetical resonances are considered, depending on the final state and model. In the absence of a significant observed excess, the results are interpreted as upper limits on the production cross section of a spin-0 or spin-2 resonance. The upper limits for the spin-0 resonance are translated to exclusion contours in the context of Type-I and Type-II two-Higgs-doublet models, and the limits for the spin-2 resonance are used to constrain the Randall–Sundrum model with an extra dimension giving rise to spin-2 graviton excitations

    Search for squarks and gluinos in final states with one isolated lepton, jets, and missing transverse momentum at s√=13 with the ATLAS detector

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    We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; ANID, Chile; CAS, MOST and NSFC, China; COLCIEN-CIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS and CEA-DRF/IRFU, France; SRNSFG, Georgia; BMBF, HGF and MPG, Germany; GSRT, Greece; RGC and Hong Kong SAR, China; ISF and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; NWO, Netherlands; RCN, Norway; MNiSWand NCN, Poland; FCT, Portugal; MNE/IFA, Romania; JINR; MES of Russia and NRC KI, Russian Federation; MESTD, Serbia; MSSR, Slovakia; ARRS andMIZS, Slovenia; DST/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF andCantons of Bern andGeneva, Switzerland; MOST, Taiwan; TAEK, Turkey; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, CANARIE, Compute Canada, CRC and IVADO, Canada; Beijing Municipal Science& Technology Commission, China; COST, ERC, ERDF, Horizon 2020 and Marie Sklodowska-Curie Actions, European Union; Investissements d'Avenir Labex, Investissements d'Avenir Idex and ANR, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF, Greece; BSFNSF and GIF, Israel; La Caixa Banking Foundation, CERCA Programme Generalitat de Catalunya and PROMETEO and GenT Programmes Generalitat Valenciana, Spain; Goran Gustafssons Stiftelse, Sweden; The Royal Society and Leverhulme Trust, United Kingdom. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular from CERN, the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CCIN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy), NLT1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK) and BNL (USA), the Tier-2 facilities worldwide and large non-WLCG resource providers. Major contributors of computing resources are listed in Ref. [97].The results of a search for gluino and squark pair production with the pairs decaying via the lightest charginos into a final state consisting of two W bosons, the lightest neutralinos ((chi) over tilde (0)(1)), and quarks, are presented: the signal is characterised by the presence of a single charged lepton (e(+/-) or mu(+/-)) from a W boson decay, jets, and missing transverse momentum. The analysis is performed using 139 fb(-1) of proton-proton collision data taken at a centre-of-mass energy root s = 13 delivered by the Large Hadron Collider and recorded by the ATLAS experiment. No statistically significant excess of events above the Standard Model expectation is found. Limits are set on the direct production of squarks and gluinos in simplified models. Masses of gluino (squark) up to 2.2 (1.4 ) are excluded at 95% confidence level for a light (chi) over tilde (0)(1).ANPCyTYerPhI, ArmeniaAustralian Research CouncilBMWFW, AustriaAustrian Science Fund (FWF)Azerbaijan National Academy of Sciences (ANAS)SSTC, BelarusConselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Natural Sciences and Engineering Research Council of Canada (NSERC)NRC, CanadaCanada Foundation for InnovationCERNANID, ChileChinese Academy of SciencesMinistry of Science and Technology, ChinaNational Natural Science Foundation of China (NSFC)Departamento Administrativo de Ciencia, Tecnologia e Innovacion ColcienciasMinistry of Education, Youth & Sports - Czech Republic Czech Republic GovernmentCzech Republic GovernmentDNRF, DenmarkDanish Natural Science Research CouncilCentre National de la Recherche Scientifique (CNRS)CEA-DRF/IRFU, FranceSRNSFG, GeorgiaFederal Ministry of Education & Research (BMBF)HGF, GermanyMax Planck SocietyGreek Ministry of Development-GSRTRGC, ChinaHong Kong SAR, ChinaIsrael Science FoundationBenoziyo Center, IsraelIstituto Nazionale di Fisica Nucleare (INFN)Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of ScienceCNRST, MoroccoNetherlands Organization for Scientific Research (NWO) Netherlands GovernmentRCN, NorwayMinistry of Science and Higher Education, PolandNCN, PolandPortuguese Foundation for Science and Technology European CommissionMNE/IFA, RomaniaJINRRussian FederationNRC KI, Russian FederationMinistry of Education, Science & Technological Development, SerbiaMSSR, SlovakiaSlovenian Research Agency - SloveniaMIZS, SloveniaDST/NRF, South AfricaSpanish GovernmentSRC, SwedenWallenberg Foundation, SwedenSERI, SwitzerlandSwiss National Science Foundation (SNSF)Cantons of Bern andGeneva, SwitzerlandMinistry of Science and Technology, TaiwanMinistry of Energy & Natural Resources - TurkeyUK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC)United States Department of Energy (DOE)National Science Foundation (NSF)BCKDF, CanadaCANARIE, CanadaCompute Canada, CanadaCRC, CanadaIVADO, CanadaBeijing Municipal Science & Technology CommissionCOST, European UnionEuropean Research Council (ERC)ERDF, European UnionHorizon 2020 and Marie Sklodowska-Curie Actions, European UnionFrench National Research Agency (ANR)German Research Foundation (DFG)Alexander von Humboldt FoundationHerakleitos - EU-ESFThales GroupGreek NSRF, GreeceBSFNSF, IsraelGerman-Israeli Foundation for Scientific Research and DevelopmentLa Caixa Banking Foundation, SpainCERCA Programme Generalitat de Catalunya, SpainPROMETEO and GenT Programmes Generalitat Valenciana, SpainGoran Gustafssons Stiftelse, SwedenRoyal Society of LondonLeverhulme Trus

    Measurements of differential cross-sections in four-lepton events in 13 TeV proton-proton collisions with the ATLAS detector

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    Measurements of four-lepton differential and integrated fiducial cross-sections in events with two same-flavour, opposite-charge electron or muon pairs are presented. The data correspond to 139 fb−1 of s√ = 13 TeV proton-proton collisions, collected by the ATLAS detector during Run 2 of the Large Hadron Collider (2015–2018). The final state has contributions from a number of interesting Standard Model processes that dominate in different four-lepton invariant mass regions, including single Z boson production, Higgs boson production and on-shell ZZ production, with a complex mix of interference terms, and possible contributions from physics beyond the Standard Model. The differential cross-sections include the four-lepton invariant mass inclusively, in slices of other kinematic variables, and in different lepton flavour categories. Also measured are dilepton invariant masses, transverse momenta, and angular correlation variables, in four regions of four-lepton invariant mass, each dominated by different processes. The measurements are corrected for detector effects and are compared with state-of-the-art Standard Model calculations, which are found to be consistent with the data. The Z → 4ℓ branching fraction is extracted, giving a value of (4.41 ± 0.30) × 10−6. Constraints on effective field theory parameters and a model based on a spontaneously broken B − L gauge symmetry are also evaluated. Further reinterpretations can be performed with the provided information.info:eu-repo/semantics/publishedVersio

    Measurement of b -quark fragmentation properties in jets using the decay B ± → J/ψK ± in pp collisions at s = 13 TeV with the ATLAS detector

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    Abstract: The fragmentation properties of jets containing b-hadrons are studied using charged B mesons in 139 fb−1 of pp collisions at s = 13 TeV, recorded with the ATLAS detector at the LHC during the period from 2015 to 2018. The B mesons are reconstructed using the decay of B± into J/ψK±, with the J/ψ decaying into a pair of muons. Jets are reconstructed using the anti-kt algorithm with radius parameter R = 0.4. The measurement determines the longitudinal and transverse momentum profiles of the reconstructed B hadrons with respect to the axes of the jets to which they are geometrically associated. These distributions are measured in intervals of the jet transverse momentum, ranging from 50 GeV to above 100 GeV. The results are corrected for detector effects and compared with several Monte Carlo predictions using different parton shower and hadronisation models. The results for the longitudinal and transverse profiles provide useful inputs to improve the description of heavy-flavour fragmentation in jets

    Search for pair-production of vector-like quarks in pp collision events at root s=13 TeV with at least one leptonically decaying Z boson and a third-generation quark with the ATLAS detector

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    A search for the pair-production of vector-like quarks optimized for decays into a Z boson and a third-generation Standard Model quark is presented, using the full Run 2 dataset corresponding to 139 fb-1 of pp collisions at & RADIC;s = 13 TeV, collected in 2015-2018 with the ATLAS detector at the Large Hadron Collider. The targeted final state is characterized by the presence of a Z boson with high transverse momentum, reconstructed from a pair of same-flavour leptons with opposite-sign charges, as well as by the presence of b-tagged jets and high-transverse-momentum large-radius jets reconstructed from calibrated smaller-radius jets. Events with exactly two or at least three leptons are used, which are further categorized by the presence of boosted W, Z, and Higgs bosons and top quarks. The categorization is performed using a neural-network-based boosted object tagger to enhance the sensitivity to signal relative to the background. No significant excess above the background expectation is observed and exclusion limits at 95% confidence level are set on the masses of the vector-like partners T and B of the top and bottom quarks, respectively. The limits depend on the branching ratio configurations and, in the case of 100% branching ratio for T-+ Zt and 100% branching ratio for B-+ Zb, this search sets the most stringent limits to date, allowing mT > 1.60 TeV and mB > 1.42 TeV, respectively. & COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/). Funded by SCOAP3

    Measurement of light-by-light scattering and search for axion-like particles with 2.2 nb−1 of Pb+Pb data with the ATLAS detector

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    This paper describes a measurement of light-by-light scattering based on Pb+Pb collision data recorded by the ATLAS experiment during Run 2 of the LHC. The study uses 2.2 nb−1 of integrated luminosity collected in 2015 and 2018 at sNN = 5.02 TeV. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy ETγ> 2.5 GeV, pseudorapidity |ηγ| < 2.37, diphoton invariant mass mγγ> 5 GeV, and with small diphoton transverse momentum and diphoton acoplanarity. The integrated and differential fiducial cross sections are measured and compared with theoretical predictions. The diphoton invariant mass distribution is used to set limits on the production of axion-like particles. This result provides the most stringent limits to date on axion-like particle production for masses in the range 6–100 GeV. Cross sections above 2 to 70 nb are excluded at the 95% CL in that mass interval. [Figure not available: see fulltext.] © 2021, The Author(s)
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