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Réforme du salaire journalier de référence et trajectoires professionnelles
No full textLa réforme du salaire journalier de référence est entrée en vigueur le 1er octobre 2021 dans le cadre d’une refonte globale de l’Assurance chômage en France. Pour les demandeurs d’emploi ayant alterné périodes travaillées et de non-travaillées avant d’accéder à une indemnisation, cette réforme allonge la durée maximale des allocations chômage tout en en réduisant le montant.Cette étude évalue l’impact de cette réforme sur les trajectoires professionnelles, en tenant compte de l’exposition hétérogène des individus à la réforme. Celle-ci dépend directement du temps passé sans emploi entre le premier et le dernier jour travaillé au cours des deux dernières années
Lifecycle Wages and Human Capital Investments: Selection and Missing Data
No full textWe derive wage equations with individual specific coefficients from a structural model of human capital investment over the life cycle. This model allows for interruptions in labour market participation and deals with missing data and attrition problems. We propose a new framework that deals with missingness at random and is based on factor decompositions that allow for flexible control of selection. Our approach leads to an interactive effect wage specification, which we estimate using long administrative panel data on male wages in the private sector in France. A structural function approach shows that interruptions negatively affect average wages. Interestingly, they also negatively affect the inter-decile range of wages after twenty years. This is only partly due to the fact that interruptions are endogenous
A stochastic algorithm for deterministic multistage optimization problems
No full textInternational audienceSeveral attempt to dampen the curse of dimensionnality problem of the Dynamic Programming approach for solving multistage optimization problems have been investigated. One popular way to address this issue is the Stochastic Dual Dynamic Programming method (SDDP) introduced by Perreira and Pinto in 1991 for Markov Decision Processes.Assuming that the value function is convex (for a minimization problem), one builds a non-decreasing sequence of lower (or outer) convex approximations of the value function. Those convex approximations are constructed as a supremum of affine cuts. On continuous time deterministic optimal control problems, assuming that the value function is semiconvex, Zheng Qu, inspired by the work of McEneaney, introduced in 2013 a stochastic max-plus scheme that builds upper (or inner) non-increasing approximations of the value function. In this note, we build a common framework for both the SDDP and a discrete time version of Zheng Qu's algorithm to solve deterministic multistage optimization problems. Our algorithm generates monotone approximations of the value functions as a pointwise supremum, or infimum, of basic (affine or quadratic for example) functions which are randomly selected. We give sufficient conditions on the way basic functions are selected in order to ensure almost sure convergence of the approximations to the value function on a set of interest
Convex comparison of Gaussian mixtures
No full textInternational audienceMotivated by the study of the propagation of convexity by semi-groups of stochastic differential equations and convex comparison between the distributions of solutions of two such equations, we study the comparison for the convex order between a Gaussian distribution and a Gaussian mixture. We give and discuss intrinsic necessary and sufficient conditions for convex ordering. On the examples that we have worked out, the two conditions appear to be closely related
Litter in French urban areas — Part 2: transport dynamic and fluxes in stormwater
No full textInternational audienceUrban areas constitute a major hotspot of litter, including plastic litter, that stormwater can wash off towards waterways. However, few studies quantified and characterized litter densities in urban areas and fluxes transported by stormwater networks. Moreover, little information is available on litter transport dynamics in stormwater, and on the factors driving this transport. This study aims at characterizing and quantifying litter amounts transported by stormwater of two nested French urban catchments (total surface area of 105 ha). Litter densities relative to land uses and rain events were investigated in the same catchments as in a compagnon paper (Ledieu et al., 2024). The present study explores the impact of rain events on the transport of urban litter in stormwater. Litter collection and characterization combined with a capture/recapture experiment using tagged litter placed in stormwater inlets show total litter fluxes of 29 kg/year, in which 14 kg/year are plastics, exported at the stormwater outlet. These fluxes confirm that stormwater runoff is a considerable pathway from urban surfaces to waterways, especially regarding small plastic litter (< 2.5 cm). Item transport dynamic is however not linear and only 0.3% of the urban litter appear remobilized. Litter transport dynamics depends on several factors (urban litter densities, hydrometeorological parameters, item composition and morphologies, and stormwater management systems) that should be considered in global models
The effect of the mineral matrix during thermal analysis of polymers: Implications for microplastics characterization
No full text(IF 6.2;Q1)International audienceThe exponential growth of global plastic production complicates waste management, leading to the accumulation of microplastics in the environment. Currently, the identification and quantification of microplastics rely on various analytical methods that often require sample pretreatments, which can introduce errors.The Rock-Eval® thermal method, through the total quantity of hydrocarbon (Total HC parameter) and the temperature of their maximum release (Tpeak), identifies and quantifies polymers when individually analyzed. However, mineral matrices in natural sediments can influence these parameters. In this study, synthetic mixtures of various mineral matrices and polymers were analyzed using the thermal Rock-Eval® method.Three effects of mineral matrices on the thermal degradation of polymers have been identified: (1) catalysis, which accelerates the polymer degradation;(2) multimodal inhibition, characterized by a fractionated release of hydrocarbons, first at expected pyrolysis temperatures and then at higher temperatures; and (3) retention, which reduces total HC released. The same mineral matrix can produce different effects depending on the type of polymer with which it is mixed. For instance, illite catalyzes the degradation of polyethylene (PE), but inhibits that of polyethylene terephthalate (PET).Despite these effects, linear regressions between the Total HC and polymer content in synthetic mixtures provide a coefficient of determination (r²) of 0.99, confirming that matrix effects do not hinder polymer quantification. Furthermore, mixtures with natural matrices show effects comparable to those observed with synthetic matrices.These findings represent a first step towards understanding the effects of the matrix and confirm the possibility of using the thermal Rock-Eval® method as a simple tool to identify and quantify microplastic pollution in natural sediments
Dynamic (Mis)allocation of Investments in Solar Energy
No full textInternational audienceBecause they differ in terms of technology, size, and location, solar photovoltaic installations exhibit very heterogeneous levelized costs of producing electricity. Therefore, the present value cost of meeting a given trajectory of annual solar energy production depends on which projects are commissioned when: the observed sequence of investment decisions need not be cost-efficient. We propose a methodology to assess the magnitude of dynamic misallocation by comparing the present value cost of realized investments to a counterfactual optimal sequence of investments. Applying our methodology to France between 2005 and 2021, we find that the observed trajectory of annual solar output could have been produced at a present value cost about 30% lower than its realized value. Our optimized counterfactual suggests that investments in residential solar should have on average been postponed by seven years, while investments in medium- and large-scale installations should have occurred three to four years earlier
Quelle réforme du versement-mobilité ? Une simulation de différents scénarios
No full textInternational audienceLe versement-mobilité (VM) est un impôt dû par les employeurs publics et privés dans les communes incluses dans une Autorité Organisatrice de la Mobilité (AOM). Instauré pour la première fois en 1971 en Île-de-France puis décliné en province en 1973, il est rapidement devenu le pivot du système de financement français des transports collectifs urbains (Richer, 2021).Depuis 50 ans, les enjeux et la réglementation en matière de mobilité urbaine et régionale ont beaucoup évolué. Dernièrement, la Loi d’Orientation des Mobilités (LOM) en 2019 a transformé le paysage des acteurs de la mobilité en complétant la couverture du territoire en AOM. Le VM, lui, n’a pas beaucoup changé depuis les années 1970 à part quelques ajustements (l’un de ces ajustements étant terminologique puisque l’on parlait de versement-transport avant 2019). Pierre angulaire du financement de la mobilité, le VM apporte environ 50% des ressources des AOM... qui prélèvent cet impôt (Duron, 2021 ; Maurey et Sautarel, 2023). En effet, toutes les AOM ne bénéficient pas du VM par choix ou par impossibilité. En particulier, les Régions, même en tant qu’AOM locale, ne peuvent pas utiliser cette ressource tandis que seulement 26 communautés de communes sur les 421 nouvelles AOM (6%) ont instauré un VM pour financer leurs politiques de mobilité (données 2022). Finalement, hors Île-de-France, seules 24% des AOM locales disposent de cette ressource (représentant 65% de la population des AOM locales de province).Dans un contexte de tension sur le financement de la mobilité, le VM apparaît pour de nombreux responsables comme l’un des principaux leviers disponibles pour offrir de nouvelles marges de manœuvre budgétaire (Référence des tribunes politiques récentes). Cette communication propose de tester des scénarios d’évolution du VM selon différentes modalités. Pour cela, nous exploitons les fichiers localisés des rémunérations et de l’emploi salarié (FLORES-Etablissements-INSEE) afin de disposer à la fois des effectifs salariés, des rémunérations brutes, de l’activité principale exercées et du code géographique des établissements. Ces fichiers nous permettent de calculer la masse salariale des entreprises dans le périmètre des AOM qui lèvent le VM mais aussi des entreprises localisées en dehors. En cela, il nous est possible de calculer les montants de VM pour différents niveaux de taux de VM sur n’importe quel territoire en France.Nous formulons des scénarios présentant des atouts et des contraintes pour différents types d’acteurs et d’objectifs (par exemple, contribuer au financement des SERM). Ces scénarios s’inspirent en partie des prises de position récentes et publics d’acteurs politiques (par exemple, GART, Région de France, Sénat). L’objectif est de donner des ordres de grandeur sur le potentiel fiscal de chaque modalité en vue d’évaluer la pertinence de modifier le VM tel qu’il fonctionne actuellement et son efficacité
Des verbes supports qui ne sont pas des verbes
No full textInternational audienceIn support verb constructions (SVC), a.k.a. light verb constructions, as 'have poise', the support verb is explicitly assumed to be a verb, here 'have'. However, during the last 50 years, the notion of SVC has been extended to a large range of new cases. With this new scope, the linguistic form that plays the role of the support verb can also be an expression not classified as a verb, such as 'be mad with', or an adjective, e.g. 있다 issta ‘there is’ in Korean.Calling ‘support verb’ a non-verb is a terminological issue. Beyond that, this article examines the validity of extending the definition of SVCs. After surveying the linguistic forms at stake and the reactions to such extension, we focus on delimiting the historical, stricto sensu SVCs based on criteria, in a way that matches the traditional intuition. Then, for each type of linguistic form proposed as an extension, we examine how far the extension distorts this notion. We find both SVCs and extensions of SVC to be of interest in a model of syntax and the lexicon. Finally, the ‘verb’ part of speech is not essential to any of the categories, which suggests adopting the terms of ‘support construction’ and ‘extension of support construction’ instead.Dans les constructions à verbe support (CVS), comme « avoir de l'assurance », on présuppose explicitement que le verbe support est bien un verbe, ici « avoir ». Cependant, au cours des cinquante dernières années, la notion de CVS s'est étendue à un large éventail de nouveaux cas. Avec cette redélimitation, la forme linguistique qui joue le rôle de verbe support peut également être une expression qui n'est pas classée comme verbe, par exemple « être plein de », ou encore peut être un adjectif, comme 있다 issta « il y a » en coréen.Qualifier de « verbe support » une forme qui n'est pas un verbe amène à des complications terminologiques. Au-delà de cette remarque, cet article examine la validité d'une extension de la définition des CVS. Après avoir passé en revue les formes linguistiques en jeu et les réactions des linguistes à une telle extension, nous nous attachons à délimiter les CVS historiques stricto sensu sur la base de critères, mais d'une manière qui cadre avec l'intuition traditionnelle. Ensuite, pour chaque type de forme linguistique proposée comme extension, nous examinons dans quelle mesure l'extension dévie de cette notion stricto sensu. Nous montrons que les CVS et leurs extensions présentent toutes les deux un intérêt pour un modèle de la syntaxe et du lexique. Enfin, la partie verbale du discours n'est essentielle à aucune des catégories, ce qui suggère d'adopter plutôt les termes de « construction de support » et d'« extension de construction de support ».Em construções com verbo suporte (CVS), como "ter confiança", assume-se explicitamente que o verbo suporte é de fato um verbo, neste caso, "ter". No entanto, nos últimos cinquenta anos, a noção de CVS expandiu-se para uma ampla gama de novos casos. Com essa redefinição, a forma linguística que atua como verbo suporte também pode ser uma expressão que não é classificada como verbo, por exemplo, "estar cheio de", ou pode ser um adjetivo, como 있다 issta "há" em coreano.Chamar de "verbo suporte" uma forma que não é um verbo leva a complicações terminológicas. Além desta observação, este artigo examina a validade da extensão da definição de CVS. Após revisar as formas linguísticas envolvidas e as reações dos linguistas a tal extensão, nos concentramos em delimitar os CVS históricos stricto sensu com base em critérios, mas de uma forma que recapture a intuição tradicional. Em seguida, para cada tipo de forma linguística proposta como extensão, examinamos em que medida a extensão desvia dessa noção stricto sensu. Mostramos que tanto os CVS quanto suas extensões são de interesse para um modelo da sintaxe e do léxico. Por fim, a classe gramatical verbal não é essencial para nenhuma das categorias, o que sugere a adoção dos termos "construção de suporte" e "extensão da construção de suporte"
