26 research outputs found

    Prevention of bronchial hyperreactivity in a rat model of precapillary pulmonary hypertension

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    <p>Abstract</p> <p>Background</p> <p>The development of bronchial hyperreactivity (BHR) subsequent to precapillary pulmonary hypertension (PHT) was prevented by acting on the major signalling pathways (endothelin, nitric oxide, vasoactive intestine peptide (VIP) and prostacyclin) involved in the control of the pulmonary vascular and bronchial tones.</p> <p>Methods</p> <p>Five groups of rats underwent surgery to prepare an aorta-caval shunt (ACS) to induce sustained precapillary PHT for 4 weeks. During this period, no treatment was applied in one group (ACS controls), while the other groups were pretreated with VIP, iloprost, tezosentan via an intraperitoneally implemented osmotic pump, or by orally administered sildenafil. An additional group underwent sham surgery. Four weeks later, the lung responsiveness to increasing doses of an intravenous infusion of methacholine (2, 4, 8 12 and 24 μg/kg/min) was determined by using the forced oscillation technique to assess the airway resistance (Raw).</p> <p>Results</p> <p>BHR developed in the untreated rats, as reflected by a significant decrease in ED<sub>50</sub>, the equivalent dose of methacholine required to cause a 50% increase in Raw. All drugs tested prevented the development of BHR, iloprost being the most effective in reducing both the systolic pulmonary arterial pressure (Ppa; 28%, p = 0.035) and BHR (ED<sub>50 </sub>= 9.9 ± 1.7 vs. 43 ± 11 μg/kg in ACS control and iloprost-treated rats, respectively, p = 0.008). Significant correlations were found between the levels of Ppa and ED<sub>50 </sub>(R = -0.59, p = 0.016), indicating that mechanical interdependence is primarily responsible for the development of BHR.</p> <p>Conclusions</p> <p>The efficiency of such treatment demonstrates that re-establishment of the balance of constrictor/dilator mediators via various signalling pathways involved in PHT is of potential benefit for the avoidance of the development of BHR.</p

    Measurement of the Z/gamma* + b-jet cross section in pp collisions at 7 TeV

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    The production of b jets in association with a Z/gamma* boson is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7 TeV and recorded by the CMS detector. The inclusive cross section for Z/gamma* + b-jet production is measured in a sample corresponding to an integrated luminosity of 2.2 inverse femtobarns. The Z/gamma* + b-jet cross section with Z/gamma* to ll (where ll = ee or mu mu) for events with the invariant mass 60 < M(ll) < 120 GeV, at least one b jet at the hadron level with pT > 25 GeV and abs(eta) < 2.1, and a separation between the leptons and the jets of Delta R > 0.5 is found to be 5.84 +/- 0.08 (stat.) +/- 0.72 (syst.) +(0.25)/-(0.55) (theory) pb. The kinematic properties of the events are also studied and found to be in agreement with the predictions made by the MadGraph event generator with the parton shower and the hadronisation performed by PYTHIA.Comment: Submitted to the Journal of High Energy Physic

    Measurement of the Zγ production cross section in pp collisions at 8 TeV and search for anomalous triple gauge boson couplings

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    Open Access, Copyright CERN, for the benefit of the CMS Collaboration. Article funded by SCOAP3.Abstract: The cross section for the production of Zγ in proton-proton collisions at 8 TeV is measured based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 19.5 fb−1. Events with an oppositely-charged pair of muons or electrons together with an isolated photon are selected. The differential cross section as a function of the photon transverse momentum is measured inclusively and exclusively, where the exclusive selection applies a veto on central jets. The observed cross sections are compatible with the expectations of next-to-next-to-leading-order quantum chromodynamics. Limits on anomalous triple gauge couplings of ZZγ and Zγγ are set that improve on previous experimental results obtained with the charged lepton decay modes of the Z boson

    Measurement of the production cross section ratio σ(χb2(1P))/σ(χb1(1P))in pp collisions at √s=8TeV

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    A measurement of the production cross section ratio σ(χb2(1P))/σ(χb1(1P))σ(χb2(1P))/σ(χb1(1P)) is presented. The χb1(1P)χb1(1P) and χb2(1P)χb2(1P) bottomonium states, promptly produced in pp collisions at View the MathML sources=8 TeV, are detected by the CMS experiment at the CERN LHC through their radiative decays χb1,2(1P)→ϒ(1S)+γχb1,2(1P)→ϒ(1S)+γ. The emitted photons are measured through their conversion to e+e−e+e− pairs, whose reconstruction allows the two states to be resolved. The ϒ(1S)ϒ(1S) is measured through its decay to two muons. An event sample corresponding to an integrated luminosity of 20.7 fb−120.7 fb−1 is used to measure the cross section ratio in a phase-space region defined by the photon pseudorapidity, |ηγ|<1.0|ηγ|<1.0; the ϒ(1S)ϒ(1S) rapidity, |yϒ|<1.5|yϒ|<1.5; and the ϒ(1S)ϒ(1S) transverse momentum, View the MathML source7<pTϒ<40 GeV. The cross section ratio shows no significant dependence on the ϒ(1S)ϒ(1S) transverse momentum, with a measured average value of View the MathML source0.85±0.07(stat+syst)±0.08(BF), where the first uncertainty is the combination of the experimental statistical and systematic uncertainties and the second is from the uncertainty in the ratio of the χbχb branching fractions

    Measurements of b-jet nuclear modification factors in pPb and PbPb collisions with CMS

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    Properties of Daily Helium Fluxes

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    We present the precision measurement of 2824 daily helium fluxes in cosmic rays from May 20, 2011 to October 29, 2019 in the rigidity interval from 1.71 to 100 GV based on 7.6 x 10(8) helium nuclei collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The helium flux and the helium to proton flux ratio exhibit variations on multiple timescales. In nearly all the time intervals from 2014 to 2018, we observed recurrent helium flux variations with a period of 27 days. Shorter periods of 9 days and 13.5 days are observed in 2016. The strength of all three periodicities changes with time and rigidity. In the entire time period, we found that below similar to 7 GV the helium flux exhibits larger time variations than the proton flux, and above similar to 7 GV the helium to proton flux ratio is time independent. Remarkably, below 2.4 GV a hysteresis between the helium to proton flux ratio and the helium flux was observed at greater than the 7 sigma level. This shows that at low rigidity the modulation of the helium to proton flux ratio is different before and after the solar maximum in 2014

    Measurement of the pp → ZZ production cross section and constraints on anomalous triple gauge couplings in four-lepton final states at vs=8TeV

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    A measurement of the inclusive ZZ production cross section and constraints on anomalous triple gauge couplings in proton–proton collisions at vs=8 TeV are presented. The analysis is based on a data sample, corresponding to an integrated luminosity of 19.6fb-1, collected with the CMS experiment at the LHC. The measurements are performed in the leptonic decay modes ZZ ? lll’l’, where l =e, µand ll=e, µ, t. The measured total cross section s(pp ?ZZ) =7.7 ±0.5(stat)+0.5-0.4(syst)±0.4 (theo) ±0.2(lumi) pb, for both Z bosons produced in the mass range 60 <mZ<120GeV, is consistent with standard model predictions. Differential cross sections are measured and well described by the theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZand ZZ?couplings at the 95% confidence level: -0.004 <fZ4<0.004, -0.004 <fZ5<0.004, -0.005 <f?4<0.005, and -0.005 <f?5<0.005
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