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Comment diffuser et partager les données géographiques et marines pour faciliter leur réutilisation ?: Sur la diffusion des données et des logiciels de la recherche dans le cadre de la Science ouverte
No full textInternational audienceObjectif : faciliter la réutilisation et la FAIRisation des données géographiques et marinescollectées et produites par les équipes de recherche dans le contexte évolutif de la Science ouvertedemande une diffusion réalisée dans un cadre maîtrisé, avec une licence qui permet, entre autres,la réutilisation et la modification de cette production, et en traitant correctement les questionsjuridiques, s'il y en a. Nous proposons un cadre de partage homogène à celui des logiciels de la recherche.</div
Resolutions in a system of financially linked firms: relying on coarse information
No full textInternational audienceIn a financial system, firms hold debts both within and outside the system. To limit miscoordination and cascades of defaults, an orderly resolution must be conducted at the system level and simultaneously liquidate all debts. This paper analyzes such resolutions under two main assumptions. First, a default on external creditors, say on banks' customers, triggers bankruptcy and should be avoided as much as possible because of large negative externalities. Second, resolutions are coarse, as they specify the payments between each firm and its external creditors and the system without specifying the reimbursement of each bilateral liability. I present properties that determine which firms become bankrupt and how much each non-bankrupt firm reimburses to and receives from the system. The main properties rely on the priority of external creditors at the system level, which reflects the policy recommendations after the 2018 financial crisis, and the proportionality principle
QBOi El Niño Southern Oscillation experiments: Assessing relationships between ENSO, MJO, and QBO
No full textInternational audienceAbstract. This study uses an ensemble of climate model experiments coordinated by the Quasi-Biennial Oscillation initiative (QBOi) to analyze the Madden-Julian Oscillation (MJO) in the presence of either perpetual El Niño or La Niña sea surface temperatures during boreal winter. In addition to the prescribed El Niño Southern Oscillation (ENSO) conditions, the nine models internally generate QBOs, meaning each may influence the MJO. The diagnostics used include wavenumber-frequency spectra of tropical convective and dynamical fields, measures of MJO lifetime, an evaluation of MJO diversity and visualizations of MJO vertical structure, as well as an assessment of QBO morphology and the QBO’s impact on tropical convection. Kelvin wave spectral power increases in the El Niño simulations whereas equatorial Rossby waves power is stronger in the La Niña simulations. Consistent with the reported relationship between these waves and the MJO, all models simulate faster MJO propagation under El Niño conditions. This change in speed is corroborated by the MJO diversity analysis, which reveals that models better reproduce the observed “fast propagating” and “standing” MJO archetypes given perpetual El Niño and La Niña, respectively. Regardless of ENSO, QBO descent into the lower stratosphere is underestimated and we detect little QBO influence on tropical tropopause stability and MJO activity. With little influence from the QBO on the MJO activity in these runs, we can be confident that the aforementioned changes in the MJO indeed arise from the different ENSO boundary conditions
Avis du conseil scientifique du comité de bassin Seine-Normandie sur les gestions alternatives des urines et matières fécales humaines.Un potentiel d’amélioration conjointe de la gestion de l’eau et de la souveraineté alimentaire
No full textCet avis vise à remettre en débat le mode de gestion des excrétats humains (urines et matières fécales) vers des alternatives davantage sobres et circulaires, présentant des bénéfices potentiels sur les plans hydriques, environnementaux, sanitaires, économiques et de souveraineté alimentaire. Depuis plusieurs décennies, le tout-à-l’égout est le mode dominant de gestion des excrétats humains dans les villes occidentales, ce qui tend à le faire considérer comme naturel. Pourtant, les limites de ce mode de gestion, majoritairement linéaire, présentent de forts enjeux en termes de soutenabilité et de résilience. Les nombreuses alternatives à ce mode de gestion, communément nommées « séparation à la source des excrétats humains », tendent à se développer depuis dix ans sur le bassin Seine Normandie, au point que ce bassin est désormais devenu une référence mondiale en matière de séparation à la source des excrétats humains (Binz, 2024). Les filières professionnelles de gestion alternative pour une valorisation agricole sont actuellement en émergence. Il y a un intérêt stratégique à favoriser le développement de ces filières, ce qui nécessite le soutien de la puissance publique et la coordination des acteurs. À court terme, de très nombreuses opportunités « sans regret » sont à saisir. À long terme, le déploiement de la séparation à la source doit être pensé en articulation avec la remise en cause plus générale du paradigme actuel de gestion de l’eau et de l’alimentation, incompatible avec le respect des limites planétaires et les adaptations nécessaires aux changements climatiques et géopolitique
Computing shortest closed curves on non-orientable surfaces
No full textInternational audienceWe initiate the study of computing shortest non-separating simple closed curves with some given topological properties on non-orientable surfaces. While, for orientable surfaces, any two non-separating simple closed curves are related by a self-homeomorphism of the surface, and computing shortest such curves has been vastly studied, for non-orientable ones the classification of non-separating simple closed curves up to ambient homeomorphism is subtler, depending on whether the curve is one-sided or two-sided, and whether it is orienting or not (whether it cuts the surface into an orientable one).We prove that computing a shortest orienting (weakly) simple closed curve on a non-orientable combinatorial surface is NP-hard but fixed-parameter tractable in the genus of the surface. In contrast, we can compute a shortest non-separating non-orienting (weakly) simple closed curve with given sidedness in g^O(1).n logn time, where g is the genus and n the size of the surface.For these algorithms, we develop tools that can be of independent interest, to compute a variation on canonical systems of loops for non-orientable surfaces based on the computation of an orienting curve, and some covering spaces that are essentially quotients of homology covers
Predictive AI and productivity growth dynamics: Evidence from French firms
No full textInternational audienceWhile artificial intelligence (AI) adoption holds the potential to enhance business operations through improved forecasting and automation, its relation with average productivity growth remain highly heterogeneous across firms. This paper shifts the focus and investigates the impact of predictive artificial intelligence (AI) on the volatility of firms’ productivity growth r ates. Using firm-level data from the 2019 French ICT survey, we provide robust evidence that AI use is associated with increased volatility. This relationship persists across multiple robustness checks, including analyses addressing causality concerns. To propose a possible mechanisms underlying this effect, we compare firms that purchase AI from external providers (“AI buyers”) and those that develop AI in-house (“AI developers”). Our results show that heightened volatility is concentrated among AI buyers, whereas firms that develop AI internally experience no such effect. Finally, we find that AI-induced volatility among “AI buyers” is mitigated in firms with a higher share of ICT engineers and technicians, suggesting that AI’s successful integration requires complementary human capital
Does Feasibility Explain the Unequal Development of Working From Home?
No full textInternational audienc
Reorganizing global supply-chains: Who, What, How, and Where
No full textInternational audienceIn an ever-evolving business environment, firms are differently exposed to shocks and may or may not bear the costs of reorganizing their value chain by reshoring or offshoring. This paper studies the prevalence and modalities of such reorganizations, based on a survey of French firms on the decision to reorganize part of their value chain between January 2018 and December 2020. Such decisions turn out to be rare, carried out by firms with a higher share of skilled workers, in manufacturing rather than in services, and dominated by multinational firms. Although high-skilled firms reorganize more, the reorganized business functions are less skill-intensive and more intensive in routine tasks. Activities that are more intangibles-intensive are more likely to be reorganized within the firm. Finally, apart from reshoring in France, activities that are offshored are located close to France. India, which combines low average wages with a large pool of highly skilled labor, receives a disproportionate share of skill-intensive activities
Sharing Model Uncertainty
No full textInternational audienceThis paper examines efficient allocations in economies where consumers exhibit heterogeneous smooth ambiguity preferences and face model uncertainty with a common set of identifiable models. Aggregate endowment is ambiguous. We characterize economies where the representative consumer is of the smooth ambiguity type and derive efficient sharing rules. Heterogeneous ambiguity aversion leads to sharing rules that systematically differ from those in vNM-economies. The representative consumer’s ambiguity aversion differs from that of the typical consumer; this leads to more compelling asset-pricing predictions. We focus on point-identified models but show that our insights extend to partially-identified models
How to Incorporate Children into Labor SupplyEquations? A General Framework
No full textWe provide a novel method for modeling and estimating the impact of children on labor supply decisions. We rely on the literature on equivalence scales and collective models.Our approach considers both the time and monetary costs of raising children. Using semiparametric restrictions on individual preferences, we identify the cost of children from the curvature of the labor supply equations with low data requirements. We apply the model to PSID data from the USA and investigate the women's labor supply sensitivity, the cost of children, and the women's price of time. We find that women's labor supply is highly sensitive to wage variations. In addition, we show that mothers allocate, on average, 44% of their net total expenditures to children. Finally, by comparing our findings to those derived from other studies using children's expense data, our model provides relatively consistent predictions regarding the cost of children