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Questionable at best: why links between mitigation by single actors and global temperature goals must be made more robust
No full textInternational audienceIn the academic and grey literature, near- and mid-term mitigation trajectories by single actors (countries, firms, cities or regions) are often labelled with terms including long-term temperature goals (e.g. 1.5°C scenario). Yet direct links between single actors’ mitigation efforts in the near- to mid-term and global temperature goals in the long-term are neither consistent nor defensible without making important additional assumptions about space, time and equity. We argue that such labelling should be avoided. If labelling has to be used, these assumptions should be transparently stated, to bridge spatial and temporal scales, and to make explicit ethical judgments about the distribution of mitigation efforts
Modeling Solute Transport in Rivers: Analytical and Numerical Solutions
No full textInternational audienceThis study presents a novel analytical framework for modeling one-dimensio- nal solute transport in rivers, integrating advection, rate-limited adsorption on suspended sediments, and first-order degradation. Analytical solutions are used to validate the numerical scheme’s accuracy under idealized conditions, tested for instantaneous and continuous pollutant discharges. The research importantly investigates short-term solute accumulation in riverbeds, a crit- ical yet understudied process that affects sediment transport and pollutant fate. Applicable to a wide range of contaminants (e.g., nutrients, pesti- cides), the framework aids water quality assessment, pollution control, and risk mitigation. Implemented in the open-source SWASHES library, these solutions provide practical tools for decision-support systems and serve as reliable benchmarks to validate numerical models. By addressing transient and persistent pollutant scenarios, this work enhances predictive capabili- ties for environmental management. The approach bridges analytical and numerical methods, offering a robust foundation for simulating solute trans- port across industrial and ecological contexts, advancing sustainable water resource management
Convergence of bipartite open quantum systems stabilized by reservoir engineering
No full text33 pages. Comments welcomeInternational audienceWe study a generic family of Lindblad master equations modeling bipartite open quantum systems, where one tries to stabilize a quantum system by carefully designing its interaction with another, dissipative, quantum system - a strategy known as quantum reservoir engineering. We provide sufficient conditions for convergence of the considered Lindblad equations; our setting accommodates the case where steady states are not unique but rather supported on a given subspace of the underlying Hilbert space. We apply our result to a Lindblad master equation proposed for the stabilization of so-called cat qubits, a system that received considerable attention in recent years due to its potential applications in quantum information processing
Spanish labour market, mobility and labour shortages
No full textInternational audienceWe use a simple yet powerful approach to investigate the dynamics of worker flows across sectors in the Spanish economy. The method imposes a minimal amount of structure on the data by assuming sector-specific matching functions, and backs out the direction of workers’ search intensities across sectors using data on realised worker flows and vacancies. We find that aggregate search intensity in Spain has been increasing since the pandemic and has led aggregate labour shortages to be below pre-pandemic levels by 2023. However, this boost of search intensity is directed to industries with low matching efficiencies and job finding rates. As a result, aggregate match formation is near to a 10-years low relative to the number of matches that would result if search intensity was allocated to maximise total matches given the observed vacancy distribution and match efficiencies across sectors
Zola's “Ladies Paradise” and the “creative destruction” theory
No full textInternational audienceZola’s Ladies Paradise may be read as a romance. A poor young woman is hired as a salesperson by a tycoon who is launching the first department store, the “ladies paradise”, in mid-19th century Paris. After several twists and turns, inventive enough for having inspired several modern-day filmmakers, they fall in love and marry. Behind this love story, however, the novel is also to be read as a deep reflection on economic progress, showing, in particular, how a major innovation may fulfil the dreams of some, the mid- and high-bourgeoisie customers or the newly hired white-collars and salespersons, while destroying the life of others, the traditional neighbouring merchant families outcompeted by the new store.Published the year of Marx’s death, the novel echoes his concerns about the social consequences of capitalist growth. Despite the tragic description of shops and families displaced by the swelling department store, however, hope and faith in the future set the tone of the novel, unlike Zola’s usual sombre painting of the society around him. Far-sightedly, this novel foresees the theory that would be famously put forward 70 years later by the economist Joseph Schumpeter, according to which economic “creative destruction” is the essence of capitalism and the root of economic progress
Préférence temporelle : évaluation, stabilité et malléabilité sur le cycle de vie
No full textInternational audienceLa préférence temporelle est un concept théorique important pour expliquer de nombreuses décisions individuelles impliquant un arbitrage intertemporel, notamment l’accumulation du patrimoine. Le modèle standard de l’épargnant (discounted utility) suppose que cette préférence pour le présent est rationnelle, rationalité qui correspond à des choix temporellement cohérents : l’individu ne se contredit pas dans ces choix intertemporels. La mesure quantitative de ce paramètre est le plus souvent assez simple : on fait choisir l’individu entre X euros maintenant et Y euros à une date ultérieure. Cependant, les valeurs obtenues à cette question dans les nombreuses études à notre disposition varient considérablement en fonction des montants envisagés, du type d’enquêtes choisi, des populations étudiées ou encore des biais pris en compte (préférence pour le court terme notamment). Une réflexion à la fois théorique et empirique est ici proposée pour dépasser ce « puzzle » empirique. Le concept théorique de la préférence pour le présent serait moins « paramétrique » et plus « existentiel » (rapport du moi « présent » au moi « futur » au sens philosophique). Empiriquement, cette approche renonce à toute mesure cardinale de la préférence temporelle, lui préférant une quantification ordinale à partir de diverses questions qualitatives concernant différents domaines de la vie tirées de l’enquête PAT€R. Deux applications sur lesquelles se focalise la littérature récente sont proposées à titre d’illustration : la stabilité des préférences (en période de Covid) et leur malléabilité en fonction des politiques publiques (programme d’éducation financière)
The Convention members' opinions on climate measures
No full textInternational audienceThis chapter discusses the Citizens' Convention for Climate members' opinions about climate measures, offering a fine-grained quantitative description of the link between personal characteristics and the degree of support for different policies. It exploits the individual data from questionnaires which the observing researchers passed round during various weekends. The chapter discusses the relationship between the citizens' responses regarding climate policies and these different types of information, in a bivariate approach. It verifies that the sociodemographic diversity guaranteed by the recruitment process goes hand in hand with a certain degree of heterogeneity of opinions on climate policies. France is characterized by lower levels of interpersonal trust and major distrust of the world of politics and governments, in comparison with other European countries
Inter-granular damage in experimentally deformed rock-salt investigated by X-ray micro-tomography: confining pressure and brine effects
No full textInternational audienceWe have investigated the mechanical behaviour of synthetic rock-salt during compression tests using in situ X-ray micro computed tomography (XR-μCT). Samples were deformed under controlled strain rate in an X-ray semi-transparent triaxial cell adapted to X-ray tomography.We were interested in the development of micro damage in relation to the stress state and the presence or absence of brine. For that purpose, we produced by powder compaction in œdometric cells two types of materials with different amounts of water. One is considered “laboratory dry” and the other is considered “water saturated”. Both materials exhibit similar mean grain size (c.a. 200 μm). Both types of samples were deformed at uniaxial and triaxial conditions (15 MPa confining pressure), at room temperature and constant displacement rate (1 μm/s).The results show that the dominant damage mechanisms correspond to the progressive development of diffuse inter-granular micro-cracking. This can be explained by the strong anisotropy in the crystal plasticity of NaCl, which results in local plastic strain incompatibilities between neighboring grains in the polycrystalline rock-salt. Conversely, the development of micro-crack damage is strongly reduced by both confining pressure and presence of brine. Natural Leine rock salt samples bearing inter-crystalline brine and tested under similar conditions show similar trends as regards inter-granular micro-damage. We suggest that the development of inter-granular micro-cracking is suppressed or retarded in the presence of brine thanks to dissolution-precipitation processes, which in addition to the well-known healing effect may also reduce the local plastic strain incompatibilities
Harmonizing dockless E-scooters: insights from Paris
No full textInternational audienceImproper parking is one of the most significant barriers to the adoption and acceptance of dockless shared e-scooters worldwide. This paper investigates the effects of mandatory parking regulations in Paris that require e-scooters to be parked in designated bays in the form of painted corrals. To assess the impact of these regulations and their unintended effects, we develop a novel multicriteria evaluation method around three principles: efficiency, accessibility, and compliance. Using a unique large-scale database that geolocates every parked e-scooter in the city at threehour intervals, we find that designated parking bays improve mis-parking by reducing cluttering. However, they also unintentionally reduce accessibility. Furthermore, we provide insights into the persistence of mis-parking and the congestion of parking bays, two key factors that contributed to the ban of shared e-scooters in the city
The Metropolis inside/out. Learning from the Greater Paris Region: TOD-IS-RUR Paris studio, 19-22 april 2022
No full textThe TOD-IS-RUR Innovative Training Network (ITN) has set up an interdisciplinary, international and intersectoral network to make significant research contributions to the scientific and societal challenges in countering urban sprawl in Europe. The aim of the network is to transform an urban, undifferentiated and model-based approach to TOD into a grounded, interdisciplinary rural-urban approach, fully integrating the social and environmental issues underpinning the relationships between mobility and urbanization. Within this framework, held on April 2022, the Greater Paris Studio entitled "The Metropolis inside/out" was an intensive four-day event that aimed to clarify, discuss and understand the research questions in context. This written and visual book gathers the conferences, fieldworks (walking, fiction, photography), seminars (Institut Paris Région, Atelier Parisien d'URbanisme, Architecture Recherche Engagement Post-carbone) that were delivered and implemented during this studio. It formally documents a collective reflexion, opening perspectives for further research