Elliptic anisotropy measurement of the f0_0(980) hadron in proton-lead collisions and evidence for its quark-antiquark composition

International audienceDespite the f$_0$(980) hadron having been discovered half a century ago, the question about its quark content has not been settled: it might be an ordinary quark-antiquark ($\mathrm{q\bar{q}}$) meson, a tetraquark ($\mathrm{q\bar{q}q\bar{q}}$) exotic state, a kaon-antikaon ($\mathrm{K\bar{K}}$) molecule, or a quark-antiquark-gluon ($\mathrm{q\bar{q}g}$) hybrid. This paper reports strong evidence that the f$_0$(980) state is an ordinary $\mathrm{q\bar{q}}$ meson, inferred from the scaling of elliptic anisotropies ($v_2$) with the number of constituent quarks ($n_\mathrm{q}$), as empirically established using conventional hadrons in relativistic heavy ion collisions. The f$_0$(980) state is reconstructed via its dominant decay channel f$_0$(980) $\to$$\pi^+\pi^-$, in proton-lead collisions recorded by the CMS experiment at the LHC, and its $v_2$ is measured as a function of transverse momentum ($p_\mathrm{T}$). It is found that the $n_q$ = 2 ($\mathrm{q\bar{q}}$ state) hypothesis is favored over $n_q$ = 4 ($\mathrm{q\bar{q}q\bar{q}}$ or $\mathrm{K\bar{K}}$ states) by 7.7, 6.3, or 3.1 standard deviations in the $p_\mathrm{T}$$\lt$ 10, 8, or 6 GeV/$c$ ranges, respectively, and over $n_\mathrm{q}$ = 3 ($\mathrm{q\bar{q}g}$ hybrid state) by 3.5 standard deviations in the $p_\mathrm{T}$$\lt$ 8 GeV/$c$ range. This result represents the first determination of the quark content of the f$_0$(980) state, made possible by using a novel approach, and paves the way for similar studies of other exotic hadron candidates

Multifunctional bioactive coating on biomedical β-Ti12Mo6Zr2Fe alloy to improve corrosion protection and bioactivity properties

International audienc

La politique environnementale du gouvernement britannique : le pas en arrière

Observatoire du Brexit, Groupe de recherche sur le Royaume-Uni et l’Union européenne post-Brexit, https://brexit.hypotheses.org/733

Premiers peuplements d'Amérique du Sud : les sites préhistoriques de la Serra da Capivara (Brésil) : polémiques et valorisations touristiques

Communication dans un séminaire EDYTEM - Ressources et patrimoin

Interaction between central and peripheral vision: Influence of distance and spatial frequencies

International audienceVisual scene perception is based on reciprocal interactions between central and peripheral information. Such interactions are commonly investigated through the semantic congruence effect, which usually reveals a congruence effect of centralvision on peripheral vision as strong as the reverse. The aim of the present study was to further investigate the mechanisms underlying central-peripheral visual interactions using a central-peripheral congruence paradigm through three behavioral experiments. We presented simultaneously a central and a peripheral stimulus, that could be either semantically congruent or incongruent. To assess the congruence effect of centralvision on peripheral vision, participants had to categorize the peripheral target stimulus while ignoring the central distractor stimulus. To assess the congruence effect of the peripheral vision on central vision, they had to categorize the central target stimulus while ignoring the peripheral distractor stimulus. Experiment 1 revealed that the physical distance between central and peripheral stimuli influences central-peripheral visual interactions: Congruence effect of central vision is stronger when the distance between the target and the distractor is the shortest. Experiments 2 and 3 revealedthat the spatial frequency content of distractors also influence central-peripheral interactions: Congruence effect of central vision is observed only when thedistractor contained high spatial frequencies while congruence effect of peripheral vision is observed only when the distractor contained low spatial frequencies.These results raise the question of how these influences are exerted (bottom-up vs. top-down) and are discussed based on the retinocortical properties of the visualsystem and the predictive brain hypothesis

Fraction of χc\chi_c decays in prompt J/ψJ/\psi production measured in pPb collisions at sNN=8.16\sqrt{s_{NN}}=8.16 TeV

International audienceThe fraction of $\chi_{c1}$ and $\chi_{c2}$ decays in the prompt $J/\psi$ yield, $F_{\chi c}=\sigma_{\chi_c \to J/\psi}/\sigma_{J/\psi}$, is measured by the LHCb detector in pPb collisions at $\sqrt{s_{NN}}=8.16$ TeV. The study covers the forward ($1.5<y^*<4.0$) and backward ($-5.0<y^*<-2.5$) rapidity regions, where $y^*$ is the $J/\psi$ rapidity in the nucleon-nucleon center-of-mass system. Forward and backward rapidity samples correspond to integrated luminosities of 13.6 $\pm$ 0.3 nb$^{-1}$ and 20.8 $\pm$ 0.5 nb$^{-1}$, respectively. The result is presented as a function of the $J/\psi$ transverse momentum $p_{T,J/\psi}$ in the range 1$<p_{T, J/\psi}<20$ GeV/$c$. The $F_{\chi c}$ fraction at forward rapidity is compatible with the LHCb measurement performed in $pp$ collisions at $\sqrt{s}=7$ TeV, whereas the result at backward rapidity is 2.4 $\sigma$ larger than in the forward region for $1<p_{T, J/\psi}<3$ GeV/$c$. The increase of $F_{\chi c}$ at low $p_{T, J/\psi}$ at backward rapidity is compatible with the suppression of the $\psi$(2S) contribution to the prompt $J/\psi$ yield. The lack of in-medium dissociation of $\chi_c$ states observed in this study sets an upper limit of 180 MeV on the free energy available in these pPb collisions to dissociate or inhibit charmonium state formation

Assessing Pt and Ni dissolution mechanism and kinetics of shape-controlled oxygen reduction nanocatalysts

International audienceAn electrochemical flow cell combined with inductively coupled plasma mass spectrometry (FC-ICP-MS) is a powerful tool to understand the mechanisms of metal dissolution and to develop mitigation strategies. Herein, we quantified in situ the amount of Pt and Ni atoms dissolved from PtNi/C nanocatalysts employed to electrocatalyze the oxygen reduction reaction (ORR) in proton-exchange membrane fuel cell cathode. The nanocatalysts feature similar crystallite size and Pt:Ni atomic ratio but different morphologies (spheres, octahedra, sponges). The FC-ICP-MS results reveal that the nanocatalyst morphology affects the dissolution rate of Pt and Ni but not the dissolution mechanism. We provide analytical evidence that dissolution of Pt atoms is consistently accompanied by the dissolution of Ni atoms exceeding the stoichiometric composition. Furthermore, we demonstrate that ex situ acid leaching mitigates, but does not entirely prevent, the electrochemical dissolution of Ni atoms. Stabilized Pt and Ni dissolution rates were achieved after a one hour long accelerated stress test (AST). Characterization cyclic voltammograms show that the Pt dissolution rate remains constant before and after the AST. In contrast, the dissolution rate of Ni decreases by a factor of 10 after the AST. Among various nanoparticle shapes, spherical PtNi/C nanoparticles offer the best solution regarding the Pt and Ni retention compared to other nanoparticle shapes

Grain growth and its chemical impact in the first hydrostatic core phase

International audienceContext. The first hydrostatic core (FHSC) phase is a brief stage in the protostellar evolution that is difficult to detect. Its chemical composition determine that of later evolutionary stages. Numerical simulations are the tool of choice to study these objects.Aims. Our goal is to characterize the chemical evolution of gas and dust during the formation of the FHSC. Moreover, we are interested in analyzing, for the first time with 3D magnetohydrodynamic (MHD) simulations, the role of grain growth in its chemistry.Methods. We postprocessed 2 × 105 tracer particles from a RAMSES non-ideal MHD simulation using the codes NAUTILUS and SHARK to follow the chemistry and grain growth throughout the simulation.Results. Gas-phase abundances of most of the C, O, N, and S reservoirs in the hot corino at the end of the simulation match the ice-phase abundances from the prestellar phase. Interstellar complex organic molecules such as methyl formate, acetaldehyde, and formamide are formed during the warm-up process. Grain size in the hot corino (nH > 1011 cm−3) increases forty-fold during the last 30 kyr, with negligible effects on its chemical composition. At moderate densities (1010 < nH < 1011 cm−3) and cool temperatures 15 < T < 50 K, increasing grain sizes delay molecular depletion. At low densities (nH ~ 107 cm−3), grains do not grow significantly. To assess the need to perform chemo-MHD calculations, we compared our results with a two-step model that reproduces well the abundances of C and O reservoirs, but not the N and S reservoirs.Conclusions. The chemical composition of the FHSC is heavily determined by that of the parent prestellar core. Chemo-MHD computations are needed for an accurate prediction of the abundances of the main N and S elemental reservoirs. The impact of grain growth in moderately dense areas delaying depletion permits the use of abundance ratios as grain growth proxies

An Integrated Framework for Stakeholder and Citizen Engagement in Solar Neighborhoods: This is a report from SHC Task 63: Solar neighborhood planning and work performed in Subtask B: Economic Strategies and Stakeholder Engagement

The present report proposes an integrated framework for stakeholder engagement in solar neighborhoods, informed by practical insights from behavioral science (a practice known as behavioral design). The report bookends a series of three workshops on these topics with Task 63 experts, as well as follow-up discussions in general task meetings where the topics of stakeholder analysis and behavioral design were discussed, and case studies collected. All these activities informed the design of our proposed framework.We first report the state-of-the-art on stakeholder engagement methods in urban planning practice in Section 3. In Section 4 we present insights from behavioral science and detail how their application can enrich participatory processes, contextualizing these insights to the case of solar neighborhoodplanning. This discussion culminates in the development of a stakeholder ENGAGEment-behavioral Design framework (ENGAGED), which we detail in Section 5. The framework is intended to inform engagement processes in solar neighborhood planning and highlight how several phases in the development of a solar project can be informed by engagement activities and citizen participation. In Section 6 we report a series of solar neighborhood stakeholder engagement case studies collected from Task experts. We discuss the reported activities through the lens of our ENGAGED framework, highlighting strengths and limitations. We then present in Section 7 some overall conclusions. Our report highlights that stakeholder engagement activities in solar neighborhoods at present can take many different forms. In some cases, these activities are central to the planning process, while in others their role is primarily to inform citizens and other stakeholders. By adopting a multi-stage approach, such as in our ENGAGED framework, engagement activities can be enriched throughout the life cycle of a solar project, leading to co-created outcomes that are informed by a participatory process. Finally, while behaviors of end-users are often considered, there is still ample opportunity to integrate behaviorchangeconsiderations in a wider engagement process. Insights from behavioral science could be leveraged not only to promote virtuous energy behaviors that support the integration of solar technologies (as is the case in a few of the reported case studies), but also to increase participation inoutreach events targeting citizens. Ultimately, our goal with this report is to bring further awareness to the importance of engaging with different stakeholder groups in the context of solar neighborhood planning, and provide practical guidance in this direction

An open-access web application to visualise countries’ and regions’ carbon footprints using Sankey diagrams

International audienceConsumption-based carbon assessments are essential for evaluating climate change responsibility. However, the results vary greatly depending on the boundary chosen, making them hard to understand for non-expert readers and hindering their uptake by policy makers. Sankey diagrams are a type of flow diagram where the thickness of a flow is proportional to its value. They allow to shed light on the various ways to calculate carbon footprints and on the implications of choosing one method over another. Although several multi-regional input-output databases allow for the calculation of footprints, none of them has been systematically represented as Sankey diagrams. To fill this gap, we build an open access web application to represent carbon footprints for 49 world regions between 1995 and 2019 based on EXIOBASE 3 data. We include production-based, consumption-based and consumption-based with capital endogenized accounts. We then provide examples of the insights gained with such diagrams