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Understanding the correlation between elliptic and triangular flow
No full textInternational audienceThe relative correlation between the magnitudes of elliptic flow () and triangular flow () has been accurately measured in nucleus-nucleus collisions at the LHC collider. As a function of the centrality of the collision, it changes sign and varies non-monotonically. We show that this is naturally explained by two combined effects. The first effect is a skewness in initial-state fluctuations, which is quantified by the correlation between the geometry-driven elliptic deformation in the reaction plane and the fluctuation-driven triangularity . We introduce an intensive measure of this skewness, which is generically of order unity and depends weakly on the system size and centrality. We evaluate its magnitude using Monte Carlo simulations of the initial state, which show that it is sensitive to the nucleon width. The second effect is the fluctuation of impact parameter relative to centrality classifiers used by experiment. The ATLAS collaboration uses two different centrality classifiers, the multiplicity and the transverse energy . We fit both sets of results for Pb+Pb collisions up to centrality with a single parameter, the intensive mixed skewness. Its value inferred from experiment agrees with theoretical expectations
Euclid VI. NISP-P optical ghosts
No full textInternational audienceThe Near-Infrared Spectrometer and Photometer (NISP) onboard Euclid includes several optical elements in its path, which introduce artefacts into the data from non-nominal light paths. To ensure uncontaminated source photometry, these artefacts must be accurately accounted for. This paper focuses on two specific optical features in NISP's photometric data (NISP-P): ghosts caused by the telescope's dichroic beamsplitter, and the bandpass filters within the NISP fore-optics. Both ghost types exhibit a characteristic morphology and are offset from the originating stars. The offsets are well modelled using 2D polynomials, with only stars brighter than approximately 10 magnitudes in each filter producing significant ghost contributions. The masking radii for these ghosts depend on both the source-star brightness and the filter wavelength, ranging from 20 to 40 pixels. We present the final relations and models used in the near-infrared (NIR) data pipeline to mask these ghosts for Euclid's Quick Data Release (Q1)
Beyond Log Scales: Toward Cognitively Informed Bar Charts for Orders of Magnitude Values
No full textInternational audienceIn this work, we challenge the dominant use of logarithmic scales to communicate values spanning multiple orders of magnitude—Orders of Magnitude Values (OMVs)—to the general public. Focusing on bar charts, we incorporate cognitive insights into visualization design to better align with how humans perceive OMVs. Studies in cognitive psychology suggest that, for large numerical ranges such as millions and billions, people do not think logarithmically. Instead, they perceive numbers in a piecewise linear manner, grouping values into scale words (e.g., millions) and applying linear reasoning within each group. We build upon a recently introduced piecewise linear scale, EplusM, and validate its use in bar charts, which we refer to as EplusM bar charts. We also introduce two novel variants of the EplusM bar chart informed by findings in numerical perception: Bricks, which builds on the concepts of round numbers and subitizing, and Multi-Magnitude, which leverages categorical perception of large numbers. In a crowdsourced experiment, we evaluate four bar chart designs: 1) Log, 2) EplusM, 3) Bricks, and 4) Multi-Magnitude, across value retrieval and quantitative comparison tasks. Our results show that EplusM bar charts are significantly preferred over logarithmic designs, increase user confidence, and reduce perceived mental demand, while maintaining task performance. These findings suggest that EplusM bar charts can serve as effective alternatives to logarithmic ones when visualizing OMVs for general audiences
Search for nonresonant new physics signals in high-mass dilepton events produced in association with b-tagged jets in proton-proton collisions at = 13 TeV
No full textInternational audienceA search for nonresonant new physics phenomena in high-mass dilepton events produced in association with b-tagged jets is performed using proton-proton collision data collected in 20162018 by the CMS experiment at the CERN LHC, at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 138 fb. The analysis considers two effective field theory models with dimension-six operators; involving four-fermion contact interactions between two leptons (, electrons or muons) and b or s quarks (bb and bs). Two lepton flavor combinations (ee and ) are required and events are classified as having 0, 1, and 2 b-tagged jets in the final state. No significant excess is observed over the standard model backgrounds. Upper limits are set on the production cross section of the new physics signals. These translate into lower limits on the energy scale of 6.9 to 9.0 TeV in the bb model, depending on model parameters, and on the ratio of energy scale and effective coupling, , of 2.0 to 2.6 TeV in the bs model. The latter represent the most stringent limits on this model to date. Lepton flavor universality is also tested by comparing the dielectron and dimuon mass spectra for different b-tagged jet multiplicities. No significant deviation from the standard model expectation of unity is observed
Evidence for the collective nature of radial flow in Pb+Pb collisions with the ATLAS detector
No full textInternational audienceAnisotropic flow and radial flow are two key probes of the expansion dynamics and properties of the quark-gluon plasma (QGP). While anisotropic flow has been extensively studied, radial flow, which governs the system's radial expansion, has received less attention. Notably, experimental evidence for the global and collective nature of radial flow has been lacking. This Letter presents the first measurement of transverse momentum () dependence of radial flow fluctuations () over GeV, using a two-particle correlation method in Pb+Pb collisions at TeV. The data reveal three key features supporting the collective nature of radial flow: long-range correlation in pseudorapidity, factorization in , and centrality-independent shape in . The comparison with a hydrodynamic model demonstrates the sensitivity of to bulk viscosity, a crucial transport property of the QGP. These findings establish a new, powerful tool for probing collective dynamics and properties of the QGP
Recherches sensibles et comportements organisationnels : du dilemme à l’action
No full textFNEGE 3Dans des organisations soumises à un fort environnement concurrentiel, avec un monde du travail de plus en plus fracturé, la prise en considération par les entreprises des sujets sensibles, relevant de questions éthiques (fraude, déviance, jeux de pouvoir), de tabous (addictions), de personnes fragiles (états de santé), désavantagées (discriminations), marginalisées (zone grise de la relation d’emploi) ainsi que de comportements en lien avec la vie privée (violences conjugales) devient aussi prégnante que complexe, faisant souvent écho à des enjeux de RSE. Le courant des « sensitive researches » permet de comprendre les difficultés émotionnelles, managériales et stratégiques, auxquelles sont exposées toutes les parties prenantes (dirigeants, managers opérationnels, salariés, chercheurs, etc.) et de proposer un cadre opératoire pour appréhender les dilemmes rencontrés et analyser les modes d’action appropriés. Ce numéro spécial accueillera des propositions permettant d’analyser, au prisme du sensible, les conduites et modes d’action des acteurs afin de faire avancer la connaissance sur la réalité du sensible au sein des organisations et sur les comportements organisationnels associés autour de trois principales questions : Comment les individus et les collectifs appréhendent-ils les dilemmes et les conduites associés aux sujets sensibles en organisation ? En quoi le sensible amène-t-il à une réflexivité des acteurs sur eux-mêmes, sur les autres et sur les situations ? Dans quelle mesure la situation sensible amène-t-elle à des ajustements, adaptations ou innovations des acteurs
Qualitative Trends versus Quantitative Accuracy: A Case Study of LiMn<sub>1.5</sub>Ni<sub>0.5</sub>O<sub>4</sub> Cathode Material
No full textInternational audienceLiMn1.5Ni0.5O4 is a high-voltage cathode material for Li-ion batteries. The effects of Ni/Mn ordering and nickel content on its electrochemical behavior remain ambiguous. DFT can provide essential insights into these phenomena. We benchmark four exchange-correlation functionals (PBE, PBE+U, r2SCAN, and HSE06) for LixMn1.5Ni0.5O4 (x = 1, 0.5, 0) against experimental data. We evaluate key properties: operating voltage, voltage differences between Ni3+/Ni2+ and Ni4+/Ni3+ redox couples, magnetic and crystallographic structures, structural response upon delithiation, and oxygen K-edge EELS spectra. PBE underestimates the average voltage (3.94 V vs. 3.73 V) and overestimates redox voltage differences (114 mV vs. 15 mV), but captures essential trends in structural and electronic properties at moderate computational cost. While PBE+U improves voltage accuracy, it predicts an unstable half-lithiated phase and incorrect magnetic configurations. r2SCAN yields mixed results. HSE06 provides the highest accuracy for some results but at significant computational expense. PBE emerges as the best compromise for modeling LixMn1.5Ni0.5O4 phases
L'importance de la coopération dans les politiques de conservation de la biodiversité
No full textInternational audienceCollective schemes are promising tools for improving biodiversity conservation policies within rural landscapes. Yet, despite being at the core of their design, cooperation and its underlying mechanisms have seldom been addressed explicitly by the literature on the topic. Our paper addresses this gap in the case of the agglomeration bonus (AB), by assessing the benefits of landowners’ cooperation in conserving biodiversity through ABs with varying degrees of “collectiveness” (i.e., differing in terms of the “rules” governing landowners’ enrollment into the AB). Methodologically, we couple an ecological-economic model with a group formation game to endogenize both landowners’ cooperation and conservation responses to ABs characterized by different landowner-level enrollment rules and plot-level payments. Solving the model numerically on fictitious landscapes, we show that larger groups conserve biodiversity more cost-effectively. Findings indicate that the “value of cooperation” – defined as the difference in biodiversity achieved through collective vs. individual responses to the same plot-level payments – amounts to between 10 and 45 percent. As it leads to the highest degree of cooperation, we show that “open-list ABs” are generally the most cost-effective schemes, followed by “closed-list ABs” (where, contrary to open-list ABs, landowners can exclude someone from the group), “individual ABs” (where “groups” are limited to one landowner), and, finally, standard homogeneous payments (where bonuses are null). These results stress the importance of the very design of collective schemes to boost the effectiveness of conservation policies.Les dispositifs collectifs constituent des outils prometteurs pour améliorer les politiques de conservation de la biodiversité dans les espaces ruraux. Pourtant, bien qu’elles soient au cœur de leur conception, la coopération et ses mécanismes sous-jacents ont rarement été abordés de manière explicite dans la littérature sur le sujet. Notre article comble cette lacune dans le cas du bonus d'agglomération (BA), en évaluant les avantages de la coopération des propriétaires fonciers pour la conservation de la biodiversité par le biais de BA présentant différents degrés de « collectivité » (c'est-à-dire différant en termes de « règles » régissant l'adhésion des propriétaires fonciers au BA). Sur le plan méthodologique, nous associons un modèle éco-économique à un jeu de formation de groupes afin d’endogéniser à la fois la coopération des propriétaires fonciers et les réponses de conservation aux AB caractérisées par différentes règles d’adhésion au niveau des propriétaires fonciers et différents paiements au niveau des parcelles. En résolvant le modèle numériquement sur des paysages fictifs, nous montrons que les groupes plus importants préservent la biodiversité de manière plus rentable. Les résultats indiquent que la « valeur de la coopération » – définie comme la différence de biodiversité obtenue grâce à des réponses collectives par rapport à des réponses individuelles aux mêmes paiements au niveau des parcelles – se situe entre 10 et 45 %. Comme ils conduisent au plus haut degré de coopération, nous montrons que les « AB à liste ouverte » sont généralement les programmes les plus rentables, suivis des « AB à liste fermée » (où, contrairement aux AB à liste ouverte, les propriétaires fonciers peuvent exclure quelqu’un du groupe), des « AB individuels » (où les « groupes » se limitent à un seul propriétaire foncier) et, enfin, des paiements homogènes standard (où les primes sont nulles). Ces résultats soulignent l’importance de la conception même des dispositifs collectifs pour renforcer l’efficacité des politiques de conservation
A Comprehensive Assessment of Cancer Patient Performance Status Documentation in a Large, Multicentre Hospital System
No full textInternational audienceBackground: The performance status (PS) is an indicator of a cancer patient's ability to perform everyday activities and plays a key role in oncology. Research suggests that the documentation of PS scores in electronic health records (EHR) is deficient. Methods: We analysed PS score documentation (Karnofsky or ECOG/Zubrod/WHO) in the hospital, consultation, and multidisciplinary team meeting (MDT) records of patients newly referred for a cancer at a large, public, multisite hospital system, between 1 January 2019 and 1 June 2021. We developed a regular expression (RegEx) to automatically identify PS in documents and assessed what patient and hospital characteristics were associated with PS documentation. Results: Our RegEx achieved accuracy, and weighted-and macro-average F1 score, > 0.95 for all document types. We included 68,479 patients. 35% had a documented PS between -90 and +365 days of their first ICD-10 cancer code. 18% of MDT reports contained a PS score. In multivariate analysis, without accounting for metastatic status at diagnosis, odds ratios (ORs) for PS documentation in patient files varied by cancer type, from 0.47 (95% confidence interval: [0.42; 0.52]) for genitourinary to 3.30 [3.00; 3.61] for lung cancer, and hospital, from 0.27 [0.23; 0.33] to 3.38 [3.14; 3.63]. Male patients were more likely to have a documented PS (OR = 1.08 [1.04; 1.13]), as well as older patients. The number of each type of document was positively correlated with the presence of a score. When adding metastatic status at diagnosis, the OR for metastatic status was large (3.29 [3.13; 3.46]), but associations with other covariates were not noticeably affected. Documented PS close to diagnosis was associated with poorer 1-year survival (25% of patients with PS died within 1 year, vs 12% without PS). Conclusion: PS score documentation was variable and generally low. Improved documentation is required if EHRs are to be used as a source of real-world data
Who is responsible for responsible Artificial Intelligence at work? An employee competence perspective
No full textInternational audienceGenerative Artificial Intelligence (GenAI) is rapidly becoming embedded in everyday work, yet employees increasingly bear responsibility for how these systems are used, interpreted, and acted upon. While existing research has examined organisational adoption and managerial governance of AI, far less is known about the employee-level competences required to engage with GenAI responsibly in daily work. Drawing on holistic competence theory and the Job Demands–Resources framework, we conceptualise Responsible Generative AI Competences (RGAIC) as a multidimensional personal resource encompassing cognitive, functional, social, meta, and ethical capabilities. Using a multi-phase empirical programme with working professionals, we demonstrate that RGAIC is shaped by GenAI-focused training and is positively associated with GenAI-enabled job engagement, explaining variance beyond related constructs such as AI literacy and professional competencies. Our findings advance understanding of employee–GenAI interaction by theorising responsibility as an employee-level resource rather than a purely managerial or technical concern. We discuss implications for future research on human–AI collaboration, employee motivation, and the design of work in GenAI-enabled organisations