337 research outputs found
Optimal design of hydrometric station networks based on complex network analysis
No full textHydrometric networks play a vital role in providing information for decision-making in water resource management. They should be set up optimally to provide as much information as possible that is as accurate as possible and, at the same time, be cost-effective. Although the design of hydrometric networks is a well-identified problem in hydrometeorology and has received considerable attention, there is still scope for further advancement. In this study, we use complex network analysis, defined as a collection of nodes interconnected by links, to propose a new measure that identifies critical nodes of station networks. The approach can support the design and redesign of hydrometric station networks. The science of complex networks is a relatively young field and has gained significant momentum over the last few years in different areas such as brain networks, social networks, technological networks, or climate networks. The identification of influential nodes in complex networks is an important field of research. We propose a new node-ranking measure - the weighted degree-betweenness (WDB) measure - to evaluate the importance of nodes in a network. It is compared to previously proposed measures used on synthetic sample networks and then applied to a real-world rain gauge network comprising 1229 stations across Germany to demonstrate its applicability. The proposed measure is evaluated using the decline rate of the network efficiency and the kriging error. The results suggest that WDB effectively quantifies the importance of rain gauges, although the benefits of the method need to be investigated in more detail © Author(s) 2020
Dietary alpha-cyclodextrin reduces atherosclerosis and modifies gut flora in apolipoprotein E-deficient mice
No full textScope: alpha-Cyclodextrin (alpha-CD), a cyclic polymer of glucose, has been shown to lower plasma cholesterol in animals and humans; however, its effect on atherosclerosis has not been previously described. Methods and results: apoE-knockout mice were fed either low-fat diet (LFD; 5.2% fat, w/w), or Western high fat diet (21.2% fat) containing either no additions (WD), 1.5% alpha-CD (WDA); 1.5% beta-CD (WDB); or 1.5% oligofructose-enriched inulin (WDI). Although plasma lipids were similar after 11 weeks on theWDvs. WDA diets, aortic atherosclerotic lesions were 65% less in mice on WDA compared toWD (P < 0.05), and similar tomice fed the LFD. No effect on atherosclerosis was observed for the other WD supplemented diets. By RNA-seq analysis of 16S rRNA, addition of alpha-CD to the WD resulted in significantly decreased cecal bacterial counts in genera Clostridium and Turicibacterium, and significantly increased Dehalobacteriaceae. At family level, Comamonadaceae significantly increased and Peptostreptococcaceae showed a negative trend. Several of these bacterial count changes correlated negatively with % atherosclerotic lesion and were associated with increased cecum weight and decreased plasma cholesterol levels. Conclusion: Addition of alpha-CD to the diet of apoE-knockoutmice decreases atherosclerosis and is associated with changes in the gut flora
Higgs boson production cross-section measurements and their EFT interpretation in the 4 ℓ decay channel at √s= 13 TeV with the ATLAS detector
No full textHiggs boson properties are studied in the four-lepton decay channel (where lepton = e, μ) using 139 fb - 1 of proton–proton collision data recorded at s=13 TeV by the ATLAS experiment at the Large Hadron Collider. The inclusive cross-section times branching ratio for H→ ZZ∗ decay is measured to be 1.34 ± 0.12 pb for a Higgs boson with absolute rapidity below 2.5, in good agreement with the Standard Model prediction of 1.33 ± 0.08 pb. Cross-sections times branching ratio are measured for the main Higgs boson production modes in several exclusive phase-space regions. The measurements are interpreted in terms of coupling modifiers and of the tensor structure of Higgs boson interactions using an effective field theory approach. Exclusion limits are set on the CP-even and CP-odd ‘beyond the Standard Model’ couplings of the Higgs boson to vector bosons, gluons and top quarks. © 2020, The Author(s)
Transverse momentum, rapidity, and centrality dependence of inclusive charged-particle production in root s(NN)=5.02 TeV p+Pb collisions measured by the ATLAS experiment
No full textMeasurements of the per-event charged-particle yield as a function of the charged-particle transverse momentum and rapidity are performed using p + Pbcollision data collected by the ATLAS experiment at the LHC at a centre-of-mass energy of root sNN= 5.02 TeV. Charged particles are reconstructed over pseudorapidity |eta| < 2.3and transverse momentum between 0.1GeVand 22GeVin a dataset corresponding to an integrated luminosity of 1 mu b(-1). The results are presented in the form of chargedparticle nuclear modification factors, where the p + Pbcharged-particle multiplicities are compared between central and peripheral p + Pbcollisions as well as to charged-particle cross sections measured in ppcollisions. The p + Pbcollision centrality is characterized by the total transverse energy measured in -4.9<eta<-3.1, which is in the direction of the outgoing lead beam. Three different estimations of the number of nucleons participating in the p + Pbcollision are carried out using the Glauber model and two Glauber-Gribov colour-fluctuation extensions to the Glauber model. The values of the nuclear modification factors are found to vary significantly as a function of rapidity and transverse momentum. Abroad peak is observed for all centralities and rapidities in the nuclear modification factors for chargedparticle transverse momentum values around 3GeV. The magnitude of the peak increases for more central collisions as well as rapidity ranges closer to the direction of the outgoing lead nucleus. (C) 2016 The Author(s). Published by Elsevier B.V
Search for single production of a vector-like quark via a heavy gluon in the 4b final state with the ATLAS detector in pp collisions at root s=8 TeV
No full textA search is performed for the process pp -> G* -> B-H(b) over bar/(B) over bar (H)b -> Hb (b) over bar -> b (b) over barb (b) over bar, predicted in composite Higgs scenarios, where G* is a heavy colour octet vector resonance and B-H a vector-like quark of charge -1/3. The data were obtained from pp collisions at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.5 fb(-1), recorded by the ATLAS detector at the LHC. The largest background, multijet production, is estimated using a data-driven method. No significant excess of events with respect to Standard Model predictions is observed, and upper limits on the production cross section times branching ratio are set. Comparisons to the predictions from a specific benchmark model are made, resulting in lower mass limits in the two-dimensional mass plane of m(G*) vs. m(BH). (c) 2016 The Author. Published by Elsevier B.V. This is an open access article under the CC BY license
Measurement of the t(t)over-bar production cross-section using e mu events with b-tagged jets in pp collisions at root s=13 TeV with the ATLAS detector
No full textThis paper describes a measurement of the inclusive top quark pair production cross-section (sigma(t (t) over bar)) with a data sample of 3.2 fb(-1) of proton-proton collisions at a centre-of-mass energy of root s = 13 TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electron-muon pair in the final state. Jets containing b-quarks are tagged using an algorithm based on track impact parameters and reconstructed secondary vertices. The numbers of events with exactly one and exactly two b-tagged jets are counted and used to determine simultaneously sigma(t (t) over bar) and the efficiency to reconstruct and b-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section is measured to be: s(t (t) over bar)= 818 +/- 8 (stat) +/- 27 (syst) +/- 19 (lumi) +/- 12 (beam) pb, where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the integrated luminosity and the LHC beam energy, giving a total relative uncertainty of 4.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. A fiducial measurement corresponding to the experimental acceptance of the leptons is also presented. (C) 2016 The Author(s). Published by Elsevier B.V
The ATLAS Inner Detector Trigger performance in pp collisions at 13 TeV during LHC Run 2
No full textThe design and performance of the inner detector trigger for the high level
trigger of the ATLAS experiment at the Large Hadron Collider during the 2016-18
data taking period is discussed. In 2016, 2017, and 2018 the ATLAS detector
recorded 35.6 fb, 46.9 fb, and 60.6 fb respectively of
proton-proton collision data at a centre-of-mass energy of 13 TeV. In order to
deal with the very high interaction multiplicities per bunch crossing expected
with the 13 TeV 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 -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.Comment: 81 pages in total, author list starting page 65, 44 figures, 0
tables. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TRIG-2019-03
Search for new phenomena in events with an energetic jet and missing transverse momentum in collisions at TeV with the ATLAS detector
No full textResults of a search for new physics in final states with an energetic jet and large missing transverse momentum are reported. The search uses proton-proton collision data corresponding to an integrated luminosity of 139 fb at a center-of-mass energy of 13 TeV collected in the period 2015-2018 with the ATLAS detector at the Large Hadron Collider. Compared to previous publications, in addition to an increase of almost a factor of four in the data size, the analysis implements a number of improvements in the signal selection and the background determination leading to enhanced sensitivity. Events are required to have at least one jet with transverse momentum above 150 GeV and no reconstructed leptons (, or ) or photons. Several signal regions are considered with increasing requirements on the missing transverse momentum starting at 200 GeV. Overall agreement is observed between the number of events in data and the Standard Model predictions. Model-independent confidence-level limits on visible cross sections for new processes are obtained in the range between 736 fb and 0.3 fb. Results are also translated into improved exclusion limits in models with pair-produced weakly interacting dark-matter candidates, large extra spatial dimensions, supersymmetric particles in several compressed scenarios, axion-like particles, and new scalar particles in dark-energy-inspired models. In addition, the data are translated into bounds on the invisible branching ratio of the Higgs boson.57 pages in total, author list starting page 41, 11 figures, 10 tables. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2018-0
Highlights from the ATLAS experiment
No full textAn overview of the heavy-ion results from the ATLAS experiment is given. It includes a discussion of measurements with non-UPC dimuons in Pb+Pb collisions, dijet asymmetry, charged-hadron Raa and flow harmonics in the Xe+Xe collisions, vn-pt correlations in Pb+Pb collisions, symmetric and asymmetric cumulants in small systems and many more
Photon-tagged measurements of jet quenching with ATLAS
No full textEvents containing a high transverse momentum (pT) prompt photon offer a useful tool to study the dynamics of the hot, dense medium produced in heavy ion collisions. Because photons do not carry color charge, they are unaffected by the medium, and thus provide information about the momentum, direction, and flavor (quark or gluon) of the associated hard-scattered parton before it begins to shower and become quenched. In particular, the presence of a high-pT photon can be used to select pp and Pb+Pb events with the same configuration before quenching, limiting the effects of selection biases present in other jet measurements. The large statistics pp and Pb+Pb data delivered by the LHC in 2015 thus allow for a detailed study of photon-tagged jet quenching effects, such as the overall parton energy loss and modified structure of the component of the shower which remains correlated with the initial parton direction (e.g. in cone). These can be explored as a function of photon pT, centrality, and reaction plane. In this talk, the latest status of photon-tagged jet measurements in ATLAS will be presented, including a new measurement of how the fragmentation function for jets in photon-tagged events is modified. This measurement in particular reveals a non-trivial difference relative to the analogous observable for inclusive jets
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