Aim
Emergence of extended‐spectrum beta‐lactamase (ESBL) producing with quinolone‐resistant (QR) pathogenic Enterobacteriaceae augmented the need to establish therapeutic options against them. ...Present study aimed towards determination of synergistic combination of eugenol (EG) with cefotaxime (CTX) and ciprofloxacin (CIP) to combat against this resistance and potentiation of antibacterial drugs by EG against these bacteria.
Methods and Results
Synergistic interaction between EG and CTX/CIP (FICI: 0·08–0·5) were observed among ESBL‐QR bacteria using checkerboard assay. Approximately, 2‐ to 1024‐fold minimum inhibitory concentration value reduction and 17‐ to 165 030‐fold dose reduction index strongly suggested synergistic interaction between EG and antibiotics. Cell viability assay showed reduction in log10 CFU per ml from 16·6 to 3·1 at synergistic concentration. Scanning electron microscopy further proved disruptive effect of EG on cell architecture. Eugenol and/or its combination also altered genes’ expressions that imparted antibiotic resistance by ~1·6 to ~1226 folds.
Conclusions
Reduced doses of antibiotics, bacterial morphological alterations, efflux pump down regulation, porin over expression and beta‐lactamase gene inhibition of ESBL‐QR bacteria by EG alone or in combination with CTX/CIP might have reversed antibiotic resistance profile of ESBL‐QR bacteria.
Significance and Impact of the Study
This study provided a molecular insight into action of EG and/with CTX and CIP, which might have potentiated antibiotic’s activity against ESBL‐QR bacteria.
The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190 GeV/c π^{-} beam and a transversely polarized ...ammonia target. Three azimuthal asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3 GeV/c^{2} and 8.5 GeV/c^{2}. Within the experimental uncertainties, the observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of quantum chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semi-inclusive deep-inelastic scattering (SIDIS) data. We present two other asymmetries originating from the pion Boer-Mulders TMD PDFs convoluted with either the nucleon transversity or pretzelosity TMD PDFs. A recent COMPASS SIDIS measurement was obtained at a hard scale comparable to that of these DY results. This opens the way for possible tests of fundamental QCD universality predictions.
Eight proton transverse-spin-dependent azimuthal asymmetries are extracted in four regions of the photon virtuality Q2 from the COMPASS 2010 semi-inclusive hadron measurements in deep inelastic ...muon–nucleon scattering. These Q2 regions correspond to the four regions of the di-muon mass Q2 used in the ongoing analyses of the COMPASS Drell–Yan measurements, which allows for a future direct comparison of the nucleon transverse-momentum-dependent parton distribution functions extracted from these two alternative measurements. In addition, for the azimuthal asymmetries induced by the Sivers transverse-momentum-dependent parton distribution function various two-dimensional kinematic dependences are presented. The integrated Sivers asymmetries are found to be positive with an accuracy that appears to be sufficient to test the sign change of the Sivers function predicted by Quantum Chromodynamics.
We report on the first measurement of exclusive single-photon muoproduction on the proton by COMPASS using 160GeV/c polarised μ+ and μ− beams of the CERN SPS impinging on a liquid hydrogen target. We ...determine the dependence of the average of the measured μ+ and μ− cross sections for deeply virtual Compton scattering on the squared four-momentum transfer t from the initial to the final proton. The slope B of the t-dependence is fitted with a single exponential function, which yields B=(4.3±0.6stat|sys−0.3+0.1)(GeV/c)−2. This result can be converted into a transverse extension of partons in the proton, 〈r⊥2〉=(0.58±0.04stat|sys−0.02+0.01±0.04model)fm. For this measurement, the average virtuality of the photon mediating the interaction is 〈Q2〉=1.8(GeV/c)2 and the average value of the Bjorken variable is 〈xBj〉=0.056.
The Sivers function describes the correlation between the transverse spin of a nucleon and the transverse motion of its partons. For quarks, it was studied in previous measurements of the azimuthal ...asymmetry of hadrons produced in semi-inclusive deep inelastic scattering of leptons off transversely polarised nucleon targets, and it was found to be non-zero. In this letter the evaluation of the Sivers asymmetry for gluons is presented. The contribution of the photon–gluon fusion subprocess is enhanced by requiring two high transverse-momentum hadrons. The analysis method is based on a Monte Carlo simulation that includes three hard processes: photon–gluon fusion, QCD Compton scattering and the leading-order virtual-photon absorption process. The Sivers asymmetries of the three processes are simultaneously extracted using the LEPTO event generator and a neural network approach. The method is applied to samples of events containing at least two hadrons with large transverse momentum from the COMPASS data taken with a 160 GeV/c muon beam scattered off transversely polarised deuterons and protons. With a significance of about two standard deviations, a negative value is obtained for the gluon Sivers asymmetry. The result of a similar analysis for a Collins-like asymmetry for gluons is consistent with zero.
Precise measurements of charged-kaon multiplicities in deep inelastic scattering were performed. The results are presented in three-dimensional bins of the Bjorken scaling variable x, the relative ...virtual-photon energy y, and the fraction z of the virtual-photon energy carried by the produced hadron. The data were obtained by the COMPASS Collaboration by scattering 160 GeV muons off an isoscalar 6LiD target. They cover the kinematic domain 1(GeV/c)2<Q2<60(GeV/c)2 in the photon virtuality, 0.004<x<0.4, 0.1<y<0.7, 0.20<z<0.85, and W>5 GeV/c2 in the invariant mass of the hadronic system. The results from the sum of the z-integrated K+ and K− multiplicities at high x point to a value of the non-strange quark fragmentation function larger than obtained by the earlier DSS fit.
Multiplicities of charged pions and charged hadrons produced in deep-inelastic scattering were measured in three-dimensional bins of the Bjorken scaling variable x, the relative virtual-photon energy ...y and the relative hadron energy z. Data were obtained by the COMPASS Collaboration using a 160GeV muon beam and an isoscalar target (6LiD). They cover the kinematic domain in the photon virtuality Q2>1(GeV/c)2, 0.004<x<0.4, 0.2<z<0.85 and 0.1<y<0.7. In addition, a leading-order pQCD analysis was performed using the pion multiplicity results to extract quark fragmentation functions.
Double-spin asymmetries for production of charged pions and kaons in semi-inclusive deep-inelastic muon scattering have been measured by the COMPASS experiment at CERN. The data, obtained by ...scattering a 160 GeV muon beam off a longitudinally polarised NH
3 target, cover a range of the Bjorken variable
x between 0.004 and 0.7. A leading order evaluation of the helicity distributions for the three lightest quarks and antiquark flavours derived from these asymmetries and from our previous deuteron data is presented. The resulting values of the sea quark distributions are small and do not show any sizable dependence on
x in the range of the measurements. No significant difference is observed between the strange and antistrange helicity distributions, both compatible with zero. The integrated value of the flavour asymmetry of the helicity distribution of the light-quark sea,
Δ
u
¯
−
Δ
d
¯
, is found to be slightly positive, about 1.5 standard deviations away from zero.
The transverse spin asymmetries measured in semi-inclusive leptoproduction of hadrons, when weighted with the hadron transverse momentum PT, allow for the extraction of important ...transverse-momentum-dependent distribution functions. In particular, the weighted Sivers asymmetries provide direct information on the Sivers function, which is a leading-twist distribution that arises from a correlation between the transverse momentum of an unpolarised quark in a transversely polarised nucleon and the spin of the nucleon. Using the high-statistics data collected by the COMPASS Collaboration in 2010 with a transversely polarised proton target, we have evaluated two types of PT-weighted Sivers asymmetries, which are both proportional to the product of the first transverse moment of the Sivers function and of the fragmentation function. The results are compared to the standard unweighted Sivers asymmetries and used to extract the first transverse moments of the Sivers distributions for u and d quarks.
We present a new amplitude analysis of the ηπ D-wave in the reaction π−p→ηπ−p measured by COMPASS. Employing an analytical model based on the principles of the relativistic S-matrix, we find two ...resonances that can be identified with the a2(1320) and the excited a2′(1700), and perform a comprehensive analysis of their pole positions. For the mass and width of the a2 we find M=(1307±1±6) MeV and Γ=(112±1±8) MeV, and for the excited state a2′ we obtain M=(1720±10±60) MeV and Γ=(280±10±70) MeV, respectively.
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