1,181 research outputs found

    Sum rules for total hadronic widths of mesons

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    Mass sum rules for meson multiplets derived from exotic commutators may be written for complex masses. Then the real parts give the well known mass formulae (GM-O, Schwinger, Ideal) and the imaginary ones give the corresponding sum rules for total hadronic widths. The masses and widths of the meson nonets submit to a definite orders. It thus follows that tables of the meson nonets should include information about masses, widths and the orders as well as the mixing angle. The width sum rule for the nonet complying with Schwinger mass formula may be depicted as a straight line in the (m,Γ)(m,\Gamma) plane. It is easily verifiable and satisfied better for high mass nonets.Comment: LaTeX, 4pp, 1 figure. To appear in Proceedings of "Hadron 2001

    The Wasserstein Distance as a Dissimilarity Measure for Mass Spectra with Application to Spectral Deconvolution

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    We propose a new approach for the comparison of mass spectra using a metric known in the computer science under the name of Earth Mover\u27s Distance and in mathematics as the Wasserstein distance. We argue that this approach allows for natural and robust solutions to various problems in the analysis of mass spectra. In particular, we show an application to the problem of deconvolution, in which we infer proportions of several overlapping isotopic envelopes of similar compounds. Combined with the previously proposed generator of isotopic envelopes, IsoSpec, our approach works for a wide range of masses and charges in the presence of several types of measurement inaccuracies. To reduce the computational complexity of the solution, we derive an effective implementation of the Interior Point Method as the optimization procedure. The software for mass spectral comparison and deconvolution based on Wasserstein distance is available at https://github.com/mciach/wassersteinms

    Volunteer Computing Simulation Using Repast And Mason

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    Volunteer environments usually consist of a large number of computing nodes,with highly dynamic characteristics, therefore reliable models for a planning ofthe whole computing are highly desired. An easy to implement approach to mo-delling and simulation of such environments may employ agent-based universalsimulation frameworks, such as RePast or MASON. In the course of the paperthe above-mentioned simulation frameworks are adapted to support simulationof volunteer computing. After giving implementation details, selected resultsconcerning computing time and speedup are given and are compared with theones obtained from an actual volunteer environment

    Spirulina extract improves age-induced vascular dysfunction

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    Vascular dysfunction is considered a hallmark of ageing that has been associated with altered vasomotor responses, in which nitric oxide (NO) and reactive oxygen species participate. The consumption of Spirulina extracts, with antioxidant properties, increased recently. Objective: This study investigates the effect of Spirulina aqueous extract (SAE) on the vascular function of the aorta from aged rats. Materials and methods: Aortic segments from aged male Sprague-Dawley rats (20–22 months old) were exposed to SAE (0.1% w/v, for 3 h) to analyse: (i) the vasodilator response induced by acetylcholine (ACh), by the NO donor sodium nitroprusside (SNP), by the carbon monoxide releasing molecule (CORM) and by the KATP channel opener, cromakalim (CK); (ii) the vasoconstrictor response induced by KCl and noradrenaline (NA); (iii) the production of NO and superoxide anion, and (iv) the expression of the p-eNOS and HO-1 proteins. Results: Incubation with SAE increased the expression of p-eNOS (1.6-fold) and HO-1 (2.0-fold), enhanced NO release (1.4-fold in basal and 1.9-fold in ACh-stimulated conditions) while decreased the production of superoxide (0.7-fold). SAE also increased the sensitivity (measured as pEC50) to ACh (control: −7.06 ± 0.11; SAE: −8.16 ± 0.21), SNP (control: −7.96 ± 0.16; SAE: −9.11 ± 0.14) and CK (control: −7.05 ± 0.39; SAE: −8.29 ± 0.53), and potentiated the response to KCl (1.3-fold) and to NA (1.7-fold). Conclusion: The antioxidant properties of SAE improved the vasomotor responses of aorta from aged rats. These results may support the use of Spirulina as a protection against vascular dysfunctionThis study was supported by grants from Comunidad de Madrid(S2013/ABI-2783,‘INSPIRA1-CM’) and Fondo Europeo de Desarrollo Regional to C. O. and M. F., the Spanish Ministerio deCiencia e Innovaci on (CTQ2017-86170-R) to C. O. and by theFondo de Investigaciones Sanitarias del Instituto de Salud Carlos III(PI19/01282) to M.

    Withdrawal periods after treatment of pigs with oxytetracycline in- and outside the European Union

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    Withdrawal periods are used to avoid animals being delivered to slaughter before the concentration of the antimicrobial has declined to values below the maximum residue limit (MRL). This paper characterises the withdrawal periods in force for oxytetracycline 100 mg/ml for intramuscular use in pigs. We investigated the variation in duration of the withdrawal period between 68 oxytetracycline products from 29 countries in- and outside the European Union. More specifically, we tested whether there is a regional difference, a difference between major and minor pig meat exporting countries, whether the product is long-acting or not, and whether year of market authorisation correlated with the withdrawal period. The results showed a large variation in duration of the withdrawal periods, ranging from 5 to 40 days. Variation was observed both between and within countries. Moreover, major exporting countries were associated with a longer withdrawal period than minor exporting countries (P = 0.00099). There were no regional differences, and the year of market authorisation had no impact, but long-acting products had a shorter withdrawal period than short-acting products (P = 0.048). The variation in withdrawal periods observed questions the utility of using compliance with the withdrawal period as a means of assessing whether the meat is safe for consumption. This is particularly relevant when a pig producer unintentionally delivers pigs for slaughter before the withdrawal period has expired and, aware of this, informs the abattoir. The findings call for further harmonisation in determining the withdrawal periods for all veterinary medicinal products (VMP). Until this happens, if animals are prematurely sent to slaughter, we suggest that the concentration of the VMP at the time of slaughter is calculated and compared with the MRL to determine meat safety

    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
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