45 research outputs found

    Time-periodic phases in populations of nonlinearly coupled oscillators with bimodal frequency distributions

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    The mean field Kuramoto model describing the synchronization of a population of phase oscillators with a bimodal frequency distribution is analyzed (by the method of multiple scales) near regions in its phase diagram corresponding to synchronization to phases with a time periodic order parameter. The richest behavior is found near the tricritical point were the incoherent, stationarily synchronized, ``traveling wave'' and ``standing wave'' phases coexist. The behavior near the tricritical point can be extrapolated to the rest of the phase diagram. Direct Brownian simulation of the model confirms our findings.Comment: Revtex,16 pag.,10 fig., submitted to Physica

    Asymptotic description of transients and synchronized states of globally coupled oscillators

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    A two-time scale asymptotic method has been introduced to analyze the multimodal mean-field Kuramoto-Sakaguchi model of oscillator synchronization in the high-frequency limit. The method allows to uncouple the probability density in different components corresponding to the different peaks of the oscillator frequency distribution. Each component evolves toward a stationary state in a comoving frame and the overall order parameter can be reconstructed by combining them. Synchronized phases are a combination of traveling waves and incoherent solutions depending on parameter values. Our results agree very well with direct numerical simulations of the nonlinear Fokker-Planck equation for the probability density. Numerical results have been obtained by finite differences and a spectral method in the particular case of bimodal (symmetric and asymmetric) frequency distribution with or without external field. We also recover in a very easy and intuitive way the only other known analytical results: those corresponding to reflection-symmetric bimodal frequency distributions near bifurcation points.Comment: Revtex,12 pag.,9 fig.;submitted to Physica

    Measurement of the cross section for isolated-photon plus jet production in pp collisions at √s=13 TeV using the ATLAS detector

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    The dynamics of isolated-photon production in association with a jet in proton–proton collisions at a centre-of-mass energy of 13 TeV are studied with the ATLAS detector at the LHC using a dataset with an integrated luminosity of 3.2 fb−1. Photons are required to have transverse energies above 125 GeV. Jets are identified using the anti- algorithm with radius parameter and required to have transverse momenta above 100 GeV. Measurements of isolated-photon plus jet cross sections are presented as functions of the leading-photon transverse energy, the leading-jet transverse momentum, the azimuthal angular separation between the photon and the jet, the photon–jet invariant mass and the scattering angle in the photon–jet centre-of-mass system. Tree-level plus parton-shower predictions from Sherpa and Pythia as well as next-to-leading-order QCD predictions from Jetphox and Sherpa are compared to the measurements

    A search for resonances decaying into a Higgs boson and a new particle X in the XH → qqbb final state with the ATLAS detector

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    A search for heavy resonances decaying into a Higgs boson (H) and a new particle (X) is reported, utilizing 36.1 fb−1 of proton–proton collision data at collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle X is assumed to decay to a pair of light quarks, and the fully hadronic final state is analysed. The search considers the regime of high XH resonance masses, where the X and H bosons are both highly Lorentz-boosted and are each reconstructed using a single jet with large radius parameter. A two-dimensional phase space of XH mass versus X mass is scanned for evidence of a signal, over a range of XH resonance mass values between 1 TeV and 4 TeV, and for X particles with masses from 50 GeV to 1000 GeV. All search results are consistent with the expectations for the background due to Standard Model processes, and 95% CL upper limits are set, as a function of XH and X masses, on the production cross-section of the resonance

    Search for an invisibly decaying Higgs boson or dark matter candidates produced in association with a Z boson in pp collisions at root s=13 TeV with the ATLAS detector

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    Search for exclusive Higgs and Z boson decays to ϕγ and ργ with the ATLAS detector

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    A search for the exclusive decays of the Higgs and Z bosons to a φ or ρ meson and a photon is performed with a pp collision data sample corresponding to an integrated luminosity of up to 35.6 fb−1 collected at √s = 13 TeV with the ATLAS detector at the CERN Large Hadron Collider. These decays have been suggested as a probe of the Higgs boson couplings to light quarks. No significant excess of events is observed above the background, as expected from the Standard Model. Upper limits at 95% confidence level were obtained on the branching fractions of the Higgs boson decays to φγ and ργ of 4.8 × 10−4 and 8.8 × 10−4, respectively. The corresponding 95% confidence level upper limits for the Z boson decays are 0.9 × 10−6 and 25 × 10−6 for φγ and ργ, respectively

    Pyrimidinoceptors-mediated activation of Ca2+-dependent Cl− conductance in mouse endometrial epithelial cells

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    AbstractPrevious studies have demonstrated the activation of endometrial Cl− secretion through P2Y2 (P2U) purinoceptors by extracellular ATP. The present study further explored the presence of pyrimidine-sensitive receptors in the primary cultured mouse endometrial epithelial cells using the short-circuit current (ISC) and whole-cell patch-clamp techniques. UDP induced a transient increase in ISC in a concentration-dependent manner (EC50≈8.84 μM). The UDP-induced ISC was abolished after pretreating the epithelia with a calcium chelator, 1,2-bis-(2-aminophenoxy)-ethane-N,N,N′N′tetraacetic acid-acetomethyl ester (BAPTA-AM), suggesting the dependence of the ISC on cytosolic free Ca2+. The type of receptor involved was studied by cross-desensitization between ATP and UDP. ATP or UDP desensitized its subsequent ISC response. However, when ATP was added after UDP, or vice versa, a second ISC response was observed, indicating the activation of distinct receptors, possibly pyrimidine-sensitive receptors in addition to P2Y2 (P2U) receptors. Similar results were observed in the patch-clamp experiments where UDP and ATP were shown to sequentially activate whole-cell current in the same cell. The UDP-activated whole-cell current exhibited outward rectification with delay activation and inactivation at depolarizing and hyperpolarizing voltages, respectively. In addition, the UDP-evoked whole-cell current reversed near the equilibrium potential of Cl− in the presence of a Cl− gradient across the membrane, and was sensitive to 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid (DIDS), indicating the activation of Ca2+-activated Cl− conductance. These characteristics were very similar to that of the ATP-activated whole-cell current. Taken together, our findings indicate the presence of distinct receptors, pyrimidinoceptors and P2Y2 (P2U) receptors in mouse endometrial epithelial cells. These distinct receptors appear to converge on the same Ca2+-dependent Cl− channels

    Differential Microbial Communities of Omnivorous and Herbivorous Cattle in Southern China

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    In Hong Kong, cattle were traditionally raised by farmers as draft animals to plough rice fields. Due to urbanization in the 20th century, they were gradually abandoned and became wild cattle straying in suburban Hong Kong. Recently, these cattle were observed to have become omnivorous by eating leftover barbeque food waste in country parks. Microbiome analysis was performed on fecal samples of the omnivorous cattle using deep sequencing and the resulting microbiome was compared with that of traditional herbivorous cattle in Southern China. A more diverse gut microbiome was observed in the omnivorous cattle, suggesting that microbiota diversity increases as diet variation increases. At the genus level, the relative abundance of Anaeroplasma, Anaerovorax, Bacillus, Coprobacillus and Solibacillus significantly increased and those of Anaerofustis, Butyricimonas, Campylobacter, Coprococcus, Dehalobacterium, Phascolarctobacterium, rc4.4, RFN20, Succinivibrio and Turicibacter significantly decreased in the omnivorous group. The increase in microbial community levels of Bacillus and Anaerovorax likely attributes to the inclusion of meat in the diet; while the decrease in relative abundance of Coprococcus, Butyricimonas, Succinivibrio, Campylobacter and Phascolarctobacterium may reflect the reduction in grass intake. Furthermore, an increased consumption of resistant starch likely resulted in the increase in abundance of Anaeroplasma. In conclusion, a significant change in the gut microbial community was observed in the omnivorous cattle, suggesting that diet may be one of the factors that may signal an adaptation response by the cattle to maintain feed efficiency as a consequence of the change in environment. Keywords: Cattle, Microbiome, Diet, Omnivore, Microbial diversit
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