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Variants of violence : Classifying conflict types and policies for peace
No full textThis paper studies how heterogeneity in conflict determinants and types calls for different policy responses. For this purpose, we propose a novel, data-driven classification of country contexts and corresponding conflict types. We discuss several major conflict-related themes and policy-relevant recipes for curbing fighting
-version discontinuous Galerkin time-stepping schemes for diffusive-viscous wave equation
No full textInternational audienceThis work introduces a fully discrete scheme for the diffusion-viscous wave equation (DVWe) in the second-order formulation, combining -DG time-stepping schemes with conforming finite element methods (FEM). Two major theoretical contributions are presented: (1) -version a priori error estimates in both the energy-norm and DG-norm, which are optimal in the spatial mesh size , temporal step size , and temporal polynomial order , yet suboptimal by one order in the spatial polynomial order . Furthermore, for solutions exhibiting weak singularities in time, exponential convergence in terms of the total number of temporal degrees of freedom is proven using the -refinement strategy. (2) An energy decay estimate that offers explicit bounds involving the diffusive coefficients, discretization parameters, and the Poincar\'{e} inequality constant. A series of numerical experiments are presented to validate the practical performance of the proposed approach
De la transformation institutionnelle à la transgression des frontières professionnelles : l’environnement universitaire à l’épreuve des projets NCU
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From where I live, where are the jobs? Territorial types of communes and broader geographical patterns in mainland France
No full textWorkers and jobs interact on the labor market on the basis of mutual advantage, including the respective locations. In large territories, their respective situations underlie the statistical identification of job basins and also of Functional Urban Areas (FUAs). Applications of these to comprehend the spatial configurations of workers' homes and jobs constitute top-down approaches. The article takes a bottom-up, data-driven, four step approach to feature the worker -job -place interplay, by characterizing zones in terms of residing workers and their distances to "actual jobs" that they occupy as well as to job opportunities that they might obtain. Firstly, the locations of workers (resp. jobs) are characterized by local spatial density: its statistical distributions in the respective statistical populations of area units and individuals are linked by a Lorenz curve and a Gini index of spatial inequality. Secondly, a monocentric spectrum of radius bands in log scale is devised to synthesize the statistical distribution of the distances from a worker's residence to, respectively, "Actual jobs" as occupied and "Virtual" job opportunities. Thirdly, having characterized each zone by its number of workers and the shares of the radius bands in the Actual and Virtual spectra, clustering using the k-means algorithm yields a classification of communes into six types for mainland France. Between types 0 -"Hypermetropolitan" and 1 -"Metropolitan", on one side, and types 4 -"Rural" and 5 -"Deep rural", on the other, there are type 2 -"para-metropolitan" and type 3 -"intermediate", which gathers 53% of workers on 45% of geographical space. Fourthly, from the country map of communal types stems a couple of macro spatial patterns: monocentric-metropolitan, multipolar regions and large stretches of low density. These are compared to FUAs and further detailed by profession types.</div
Unpacking Household Engel Curves
No full textAcknowledging that decision making does not happen at the household but at the individual level, can household Engel curves be safely estimated based solely on household level data? Answering this question implies to consider the intrahousehold Engel curves (IECs) and to assess how estimates of such IECs relate to standard household Engel curves estimates. Aggregating the IECs to household level reveals confounding factors in standard household Engel curves, including intra-household inequality. A unique data set for Senegal is used to estimate IECs. Large discrepancies are found between the standard estimates of Engel curves and the consistently aggregated IECs. The main source of the discrepancy is a household fixed effect on intra-household spending behavior, which is only partially offset by differences in intra-household inequality. Results suggest that income elasticity of food consumption might be overestimated by as much as 43% by the standard household Engel curve estimation
Inactualité de l'aliénation pour l'écologie politique
No full textInternational audienceIl y a dans la matrice de l'écologie politique contemporaine, en particulier française, une importance très grande du concept d'aliénation Une alienation qui n'est plus simplement une alienation par le travail comme chez Marx et d'une alienation qu'on peut définir comme une alienation par rapport à l'économie par rapport à une sphère spécifique de la pratique humaine qui est la sphère économique D'où une tendance de l'écologie politique à se penser comme post-économique ou au-delà des déterminations d'une société économique. Cette aliénation par rapport à l'économie suggère une relation particulière et critique de l'écologie politique aux concepts du discours économique, au concept que le discours économique met en circulation, et qui permet justement de penser cette pratique économique. ce que je voudrais tenter d'expliquer c'est sur quel genre de pensée économique et quel genre de conception de l'économie, du fonctionnement de l'économie cette utilisation du concept d'aliénation se base pour montrer ensuite que par certains côtés elle consiste à ignorer la dimension proprement économique et essayer de tracer ce qui est moins souvent fait, une autre histoire de l'écologie politique, justement plus soucieuse du fonctionnement économique
Quels facteurs expliquent des différentiels d'attractivité entre lignes de desserte fine du territoire ? Une analyse à partir des potentiels compatibles
No full textInternational audienceLes lignes de desserte fine du territoire constituent une proportion du réseau TER actuel qui est loin d'être négligeable. Les fréquences y sont relativement faibles, comparées aux réseaux limitrophes, et le positionnement horaire des circulations répond parfois moins aux attentes des populations riveraines qu'à des contraintes liées à l'infrastructure, dont la capacité est dimensionnante. Au-delà de solutions d'ordre purement technique visant à alléger les coûts d'exploitation sans nuire à la fréquence se pose la question de la pertinence de l'offre et de son attractivité dans des contextes où la circulation automobile demeure fluide.Nos investigations antérieures pour le compte de la région Normandie (Mimeur et al. 2021 ; Zembri 2022), puis dans le cadre du projet TELLI (Tu-Thi et al. 2024), ont mis en évidence l'écart pouvant exister entre le potentiel compatible avec le ferroviaire (POCO) et la réalité des trafics mesurés sur les lignes concernées.Cet écart n'est cependant pas constant entre les différentes lignes analysées. Par exemple, parmi l'ensemble des origines-destinations compatibles avec le transport ferroviaire, seulement 23 % des navetteurs optent pour les transports en commun comme mode de transport principal sur la ligne Rennes-Châteaubriant. Ce taux chute à 6 % pour la ligne Saumur-La Roche-sur-Yon et à 8 % pour l'Étoile ferroviaire de Saint-Pol-sur-Ternoise, des résultats très faibles qui concernent deux lignes aux niveaux de service très différents. En termes de trafic, plusieurs questions se posent. Pourquoi les voyageurs n'ont-ils pas choisi le train ? Cela est-t-il uniquement dû à la qualité du service proposé ? Si tel est le cas, une augmentation de la fréquence entraînerait-elle un report de la demande des automobilistes vers le train ? Afin de répondre à ces questions, nous proposons une méthode visant à identifier les facteurs déterminants de la transformation du potentiel compatible en usages effectifs. Cette approche fournit ainsi des leviers d'action aux décideurs publics pour capter certains trafics vers le train
Multifractal comparison of rainfall measurement with the help of a disdrometer and a mini vertically pointing Doppler radar
No full textInternational audienceLocal rainfall measurements include a wide range of methods with different concepts and assumptions. Understanding the differences enables researchers to determine the most reliable device for each rain condition. Here, we compare two such devices: Parsivel 2 (an optical disdrometer by OTT) and mini Doppler radar (part of the mini Meteorological Station by Thies). The performance assessment followed two foci: evaluating the scaling features using the framework of universal multifractals (UMs), and analysing the influence of physical parameters (drop size, wind velocity and rainfall rate). The devices were mounted on a meteorological mast, in Pays d’Othe wind farm, 110 km southeast of Paris. The mini Doppler radar returned very low rain measurements during conditions with bigger drops, and showed non-detection in light rain involving heavy wind. UM analysis revealed similar scaling behaviour for both devices, which extended to finer scales of mini Doppler radar data until 4 s beyond which white noise wasdetected
Multifractal Phase Transitions for the “Transformative Shift” Towards a Shared Value Economy
No full textInternational audienceInternational projections indicate that extreme climatic events will become more frequent and intense, leading to significant disruptions in water cycle patterns. At the same time, water remains the only irreplaceable natural resource. As a result, human economies must be prepared to confront a range of socio-economic challenges stemming from changes in the water cycle. These issues cannot be resolved through incremental improvements to existing measures. Consequently, there is a growing call for "transformative change" — a comprehensive, system-wide restructuring at various scales, akin to what physicists describe as a non-equilibrium phase transition in a complex, nonlinear system — to tackle the interconnected and persistent challenges.In recent years, there has been a growing global emphasis on funding research with greater "transformative impact." This often leads to a focus on the outcomes and content of transformative change, when the real focus should be on the underlying physics, as achieving transformative change depends fundamentally on the interactions of these underlying processes. The scientific challenge common to both socio-economic and hydrological systems lies in their pronounced spatio-temporal heterogeneity and variability within urban environments. This variability arises from the highly nonlinear interactions among the relevant variables, which produce extreme multiscale fluctuations and complex causal chains, beginning with the fact that responses are not proportional to the initial stimuli or forces.Urban geosciences introduce additional complexity compared to traditional geosciences: their physical scales are much smaller, requiring not only higher-resolution observation technologies, which is already a significant challenge, but also involve much shorter interaction times. This shorter timescale is particularly crucial for prediction, as it limits the predictability of these systems. In this context, universal multifractals (multiplicative stochastic processes) likely provide the most effective framework for establishing a common foundation that supports more diverse and collectively potent approaches to transformative environmental change. Gaining a deeper understanding of multifractal phase transitions and their practical application, alongside alternative innovations, is key to fostering transformative change.To promote such transitions, this presentation will focus on non-trivial symmetries to address much of the complexity outlined earlier. A key example is scale symmetries, which allow for the definition of scale-independent observables, in contrast to classical observables that are heavily dependent on scale. This scale dependence creates several challenges, starting with the fact that the models based on these observables are also scale-dependent. Scale-independent observables, often referred to as singularities, are significant because they capture the divergence of classical observables as resolution increases, or as we look at progressively smaller scales. The strength of this approach lies in its application to urban geosciences, specifically for: (i) defining environmental indicators for cities and their characteristics, (ii) monetizing the amenities provided by blue-green solutions in urban areas and contextualizing them socio-economically on a large scale, and (iii) developing a new form of multifractal evaluation for environmental balance - altogether enabling "transformative chift" towards the sheared value economy.The authors sincerely acknowledge the partial financial support provided by the TIGA CfHf project (https://hmco.enpc.fr/portfolio-archive/tiga/)
Multifractal analysis of Liquid Water Content vertical and temporal variability
No full textInternational audienceDriven by complex mechanisms, precipitation exhibits extreme variability across scales both in space and time. A clearer insight into this variability can be obtained by exploring multiple parameters, such as the Liquid Water Content (LWC). It is a measurement that quantifies the amount of liquid water available in the atmosphere and as such it provides valuable information about precipitation variability across space and time. While extensive research has focused on analyzing LWC variability at the surface level, studies addressing the vertical variability remain relatively limited. However, it contributes to better understanding of rainfall dynamics, and notably the variability occurring at scales smaller than radar gate.Within this scope, six months of a Micro Rain Radar PRO (MRR-PRO) observations were gathered in Ecole nationale des ponts et chaussées, Institut Polytechnique de Paris, which is located next to Paris, France. The MRR-PRO is a K-band weather radar that measures hydrometeors fall velocity up to more than 4 kilometers of altitude above its position with a 35 meters spatial resolution and a 10 seconds time step. From collected data and simple assumptions, various quantities related to rainfall drop size distribution including LWC can be derived. The generated data were analyzed to study the spatial and temporal variations of LWC using Universal Multifractals (UM); which is a physically based framework that assesses the variability of geophysical fields across wide ranges of scales with the help of only three parameters with physical interpretation.In this study, two types of UM analysis are implemented. As a first step, the time series of LWC at each altitude is studied. As a second step, vertical profiles of LWC are analyzed and UM parameters characterizing vertical variability are derived. Obtained results and their interpretation in a space-time framework will be presented and discussed.Authors acknowledge the France-Taiwan Ra2DW project for financial support (grant number by the French National Research Agency – ANR-23-CE01-0019-01)