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On Runs Tests for Directional Data and Their Local and Asymptotic Optimality Properties
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Evidence of medium response to hard probes using correlations of Z bosons with hadrons in heavy ion collisions
No full textInternational audienceThe first measurement of pseudorapidity and azimuthal angle distributions relative to the momentum vector of a Z boson for low transverse momentum () charged hadrons in lead-lead (PbPb) collisions is presented. By studying the hadrons produced in an event with a high- Z boson (40 350 GeV), the analysis probes how the quark-gluon plasma (QGP) medium created in these collisions affects the parton recoiling opposite to the Z boson. Utilizing PbPb data at a nucleon-nucleon center-of-mass energy = 5.02 TeV from 2018 with an integrated luminosity of 1.67 nb and proton-proton (pp) data at the same energy from 2017 with 301 pb, the distributions are examined in bins of charged-hadron . A significant modification of the distributions for charged hadrons in the range 1 2 GeV in PbPb collisions is observed when compared to reference measurements from pp collisions. The data provide new information about the correlation between hard and soft particles in heavy ion collisions, which can be used to test predictions of various jet quenching models. The results are consistent with expectations of a hydrodynamic wake created when the QGP is depleted of energy by the parton propagating through it. Based on comparisons of PbPb data with pp references and predictions from theoretical models, this Letter presents the first evidence of medium-recoil and medium-hole effects caused by a hard probe
Collagen microarchitecture from polarized light imaging: a biomechanics perspective
No full textInternational audienceSignificance: Collagen, the main load-bearing component in tissue, is present in all animals and forms a variety of networks from the fibrils, fibers, bundles, and lamellae into which it self-assembles. The collagen microstructure is different among tissue types, and the different microstructures give rise to tissue-specific mechanical properties. Therefore, methods for visualizing collagen fibers and their orientation are essential for understanding the biomechanical properties of tissue.Aim: Our aim in this review is to provide the basis for understanding the methodology of polarized light imaging methods and how they can be used to characterize collagen microstructure.Approach: We begin with a description of collagen microstructure and its relationship to tissue biomechanics, a basic formalism of polarized light, and how collagen interacts with polarized light. We then describe polarized light microscopy and its various forms, particularly instant polarized light microscopy, then polarizationsensitive optical coherence tomography, and last, polarization-resolved secondharmonic generation microscopy.Results: We describe methods for imaging collagen microstructure with polarized light from in vivo methods to high-resolution volumetric imaging of tissue sections.Conclusions: We intend to help those interested in using polarized light to image and understand the relationship between collagen microstructure and biomechanics
On the fusion category
No full textInternational audienceThere might exist non-rational Virasoro CFTs in two dimensions with a categorical symmetry. We calculate the necessary ingredients for a modular conformal bootstrap analysis of these theories. After reviewing the basics of fusion categories, we present the irreducible representations, the lasso maps that intertwine between different Hilbert spaces, and finally the 22-by-22 modular S matrix. We highlight the peculiarities introduced by the non-invertible nature of the symmetry. This paper is written in a pedagogical manner and can therefore serve as an accessible entry point into the literature
Influence of strangeness on the anisotropic flow of prompt D mesons in PbPb collisions at = 5.02 TeV
No full textInternational audienceThe azimuthal anisotropy of prompt D mesons produced in lead-lead (PbPb) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV is measured using data obtained with the CMS detector. The dataset corresponds to an integrated luminosity of 0.58 nb. The azimuthal anisotropy of heavy charmed mesons provides a key constraint on the interactions of charm quarks with the quark-gluon plasma (QGP) medium. These interactions include coalescence mechanisms and parton energy loss in the QGP. The anisotropy is quantified by the second- () and third-order () Fourier coefficients of the azimuthal distribution of the D mesons. The coefficient is determined in the transverse momentum range 4 40 GeV for three event centrality classes, while the coefficient is measured in the range 4 20 GeV for a single event centrality class. The results for the D mesons are compared to those previously measured for D mesons. The azimuthal anisotropy coefficients for D and D mesons are found to be consistent within the precision of this measurement, suggesting that the strangeness content of the D meson does not significantly alter its azimuthal distribution within the measured range
Analysis of lithium insertion dynamics in graphite particles using a multi-layer Cahn-Hilliard model
No full textInternational audienceWe investigate the kinetics of lithium intercalation in a single graphite particle using a multi-layer Cahn-Hilliard model. This model can resolve the lithium-rich and lithium-poor domains, and naturally exhibits the staging phenomenon. The presence of the stages leads to a complex kinetic behavior: with increasing (dis)charge rate, the system becomes inhomogeneous, and there is a transition from quasi-equilibrium to diffusion-limited dynamics. To analyze this behavior, we define weights for each of the stages thanks to a discrete Fourier analysis, as well as other indicators such as a homogeneity index. We show that (i) the apparent global intercalation kinetics differs from the law applicable for a single layer because of the presence of a structured stage at the particle surface, (ii) the effective diffusion coefficient that describes the transition from quasi-equilibrium to diffusion-limited dynamics is much lower than the tracer diffusivity, due to the non-ideal interactions between ions and their ordering in domains. Furthermore, stage 3 is suppressed with increasing charging rates, while it is hardly present in discharge, whatever the rate. This non-trivial emerging kinetics, induced by the staging phenomenon, is present even for a single graphite particle, and should be accounted for in electrode-scale models
Reputational Conservatism in Expert Advice
No full textNational audienceWe develop a tractable career–concerns model of expert recommendations with a continuous private signal. In equilibrium, advice obeys a cutoff rule: the expert recommends the risky option if and only if the signal exceeds a threshold. Under a mild relative–diagnosticity condition, the threshold is (weakly) increasing in reputation, yielding reputational conservatism. Signal informativeness and success priors lower the cutoff, while stronger career concerns raise it. A success–contingent bonus implements any target experimentation rate via a one–to–one mapping, providing an implementable design lever
Symétries locales des diffiétés
No full textIn the framework of diffieties, founded by Vinogradov, we introduce integrable infinitesimal symmetries and show that they define a one parameter pseudogroup of local diffiety morphisms. We prove some preliminary results allowing to reduce the computation of integrable infinitesimal symmetries of a given order to solving a system of partial differential equations. We provide examples for which we can reduce to a linear system that can be solved by hand computation, and investigate some consequences for the local classification of diffiety, with a special interest for testing if a diffiety is flat.Dans le cadre de la théorie des diffiétés, fondée par Vinogradov, nous introduisons les symétries infinitésimales intégrables et montrons qu'elles définissent un pseudo-groupe à un paramètre de morphismes de diffiétés. Nous prouvons des résultats préliminaires permettant de réduire le calcul de symétries intégrables d'un ordre donné à la résolution d'un système d'équations aux dérivées partielles. Nous exhibons des exemples pour lesquels on peut se ramener à un système linéaire qui peut être résolu à la main, et explorons quelques conséquences pour la classification locale des diffiétés, avec un intérêt particulier pour les critères de platitude
Straining the root on and off triggers local calcium signaling
No full textThroughout their life, plant root are submitted to mechanical stresses due to pressure exerted by the soil. So far, few studies addressed root cell deformation and calcium signaling elicited by soil compression. In this study, we designed a microchip inspired by pneumatic microvalve concept in order to deliver a lateral pressure to the root of a plant expressing the RGECO1-mTurquoise calcium reporter. Lateral pressure applied on the root induced a moderate elastic deformation of root cortical cells and elicited a multicomponent calcium signal at the onset of the pressure pulse, followed by a second one at the release of the pressure. This indicates that straining rather than stressing of tissues is relevant to trigger the calcium signal. The calcium elevation was restricted to the tissue under pressure and did not propagate. Additionally, the calcium signals exhibited a remarkable attenuation upon repetitive stimulations. Highlights - A microvalve concept mimicking lateral soil pressure was developed. - Non-damaging lateral compression of the root induces an elastic deformation of cortical cells. - A multicomponent calcium signal is elicited at the onset of a pressure pulse and upon release of the pressure. - Straining rather than stressing of tissues is relevant to trigger the calcium signal. - The calcium signal is localized at the tissue under pressure and does not propagate. - Calcium signals exhibit a remarkable attenuation upon repetitive stimulations
Observation of the rare baryonic decay and measurement of its weak decay parameter
No full textInternational audienceThe first observation of the decay is presented, using proton-proton collision data collected by the LHCb experiment between 2016 and 2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of . The signal significance exceeds seven standard deviations. Using the decay as a normalization channel, the branching fraction is measured and combined with previous LHCb results based on data collected at 7 and 8 TeV in 2011 and 2012, yielding , where the first uncertainty is statistical, the second is systematic, and the third comes from the uncertainty on the branching fraction of the normalization channel. The weak decay parameter is measured to be , indicating the presence of comparable S-wave and P-wave decay amplitudes