3,424 research outputs found

    Numerical simulation of strongly nonlinear and dispersive waves using a Green-Naghdi model

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    We investigate here the ability of a Green-Naghdi model to reproduce strongly nonlinear and dispersive wave propagation. We test in particular the behavior of the new hybrid finite-volume and finite-difference splitting approach recently developed by the authors and collaborators on the challenging benchmark of waves propagating over a submerged bar. Such a configuration requires a model with very good dispersive properties, because of the high-order harmonics generated by topography-induced nonlinear interactions. We thus depart from the aforementioned work and choose to use a new Green-Naghdi system with improved frequency dispersion characteristics. The absence of dry areas also allows us to improve the treatment of the hyperbolic part of the equations. This leads to very satisfying results for the demanding benchmarks under consideration

    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+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \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 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

    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

    Randomized comparison of primary stenting and provisional balloon angioplasty guided by flow velocity measurement.

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    BACKGROUND: Coronary stenting improves outcomes compared with balloon angioplasty, but it is costly and may have other disadvantages. Limiting stent use to patients with a suboptimal result after angioplasty (provisional angioplasty) may be as effective and less expensive. METHODS AND RESULTS: To analyze the cost-effectiveness of provisional angioplasty, patients scheduled for single-vessel angioplasty were first randomized to receive primary stenting (97 patients) or balloon angioplasty guided by Doppler flow velocity and angiography (523 patients). Patients in the latter group were further randomized after optimization to either additional stenting or termination of the procedure to further investigate what is "optimal." An optimal result was defined as a flow reserve >2.5 and a diameter stenosis <36%. Bailout stenting was needed in 129 patients (25%) who were randomized to balloon angioplasty, and an optimal result was obtained in 184 of the 523 patients (35%). There was no significant difference in event-free survival at 1 year between primary stenting (86.6%) and provisional angioplasty (85.6%). Costs after 1 year were significantly higher for provisional angioplasty (EUR 6573 versus EUR 5885; P:=0.014). Results after the second randomization showed that stenting was also more effective after optimal balloon angioplasty (1-year event free survival, 93.5% versus 84.1%; P:=0. 066). CONCLUSIONS: After 1 year of follow-up, provisional angioplasty was more expensive and without clinical benefit. The beneficial value of stenting is not limited to patients with a suboptimal result after balloon angioplasty

    Low-lying, Rydberg states of polycyclic aromatic hydrocarbons (PAHs) and cyclic alkanes

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    TD-DFT calculations of low-lying, Rydberg states of a series of polycyclic hydrocarbons and cyclic alkanes are presented. Systematic variations in binding energies and photoelectron angular distributions for the first members of the s, p and d Rydberg series are predicted for increasing molecular complexity. Calculated binding energies are found to be in very good agreement with literature values where they exist for comparison. Experimental angle-resolved photoelectron spectroscopy results are presented for coronene, again showing very good agreement with theoretical predictions of binding energies and also for photoelectron angular distributions. The Dyson orbitals for the small "hollow" carbon structures, cubane, adamantane and dodecahedrane, are shown to have close similarities to atomic s, p and d orbitals, similar to the superatom molecular orbitals (SAMOs) reported for fullerenes, indicating that these low-lying, diffuse states are not restricted to π-conjugated molecules. © 2017 the Owner Societies

    Influence of grease formulation on rolling bearings friction torque

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    lubricated with polymer greases at constant temperature. The tested greases were formulated with the same base oil (PAO) but different thickener content (polypropylene). The friction torque in rolling bearings produced by these greases was measured and the coefficients of friction under boundary and full film lubrication were numerically calculated through the approximation of the SKF friction torque model to the experimental results.The authors gratefully acknowledge the funding supported by: • National Funds through Fundação para a Ciência e a Tecnologia (FCT) under the projects PTDC/EME-PME/122271/2010 and EXCL/SEM-PRO/0103/2012; • COMPETE and National Funds through Fundação para a Ciência e a Tecnologia (FCT) under the project Incentivo/EME/LA0022/2014; • QREN: NORTE-07-0124-FEDER-000009 - Applied Mechanics and Product Development; without whom this work would not be possible

    Cotton textile with antimicrobial activity and enhanced durability produced by l-cysteine-capped silver nanoparticles

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    In this study, L-cysteine-capped silver nanoparticles (Cys-AgNPs) were successfully linked in a cotton textile, being attached in a covalent way to the cotton fibers via esterification with the hydroxyl groups from the cellulose. The AgNPs were strongly adhered to the fiber surface through coordination bonds with the thiol groups from the L-cys. In addition, they were compared with biogenic silver nanoparticles produced from fungi (bio-AgNPs). Materials and methods: The characterization of the Cys-AgNP and the bio-AgNP solutions were accomplished by UVvisible (UVVis), Z-potential, and X-ray diffraction (XRD). After the attachment of the Cys- AgNPs and the bio-AgNPs to the raw cotton, the textile surface was characterized by variable pressure scanning electron microscopy (VP-SEM), energy dispersive X-ray (EDX), and Fourier transform infrared spectroscopy (FT-IR). The antibacterial activity was performed by disk diffusion analysis. Results: The results of the UVVis analysis showed the presence of AgNPs in the Cys-AgNPs and the bio-AgNPs solutions, showing the Surface Plasmon resonance (SPR) for the AgNPs among 380420 nm. In addition, they exhibited a Z-potential of 27 and 24 mV, respectively, with the presence of elemental silver shown by the XRD analysis. The VP-SEM images from the cotton fabrics covered in Cys-AgNPs and bio-AgNPs showed the presence of spherical AgNPs on their surface, and EDX analysis revealed the presence of peaks associated with the presence of Ag, C, and O. Furthermore, FT-IR analysis exhibited peaks associated with the presence of L-cysteine (SH-) and carboxylic acid arising from the esterification reaction among the cellulose from cotton and the carboxylic acid in the L-Cys molecules. Finally, the cotton textile exhibited antibacterial activity against Escherichia coli and Staphylococcus aureus. Conclusions: This study demonstrates the ability of Cys-AgNPs to bind to the cellulose from cotton fabric so as to produce antibacterial fabrics with enhanced durability, opening a wide range of options to be further used in healthcare and other industries.info:eu-repo/semantics/publishedVersio

    Correlated long-range mixed-harmonic fluctuations measured in pp, p+Pb and low-multiplicity Pb+Pb collisions with the ATLAS detector

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    For abstract see published article
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