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How to disseminate the research results on climate change impacts in cities to guide adaptation public policies ? Application to the Paris region (France)
No full textInternational audienceThe construction of efficient climate services relies on the interaction between decision-makers and scientists. Urban heat island is an issue that already preoccupies public authorities and is likely to be exacerbated by climate change, making assessment of its evolution crucial for effective urban policymaking and to size adaptation measures. This study analyzed interviews with 13 public stakeholders in the Paris area (France), highlighting their diverse needs for urban climate data. Their feedback on the high-resolution climate projections for the Paris region was assessed to provide recommendations to researchers for the effective dissemination of urban climate data. Public stakeholders in the Paris area need urban climate data for various purposes (awareness, diagnosis, decision support, and evaluation) and thus seek diverse types and formats of information. High-resolution climate projections may meet parts of these needs, but two key points require attention: (i) climate models appear to be difficult to apprehend by public stakeholders, thus an effort of pedagogy is necessary, (ii) climate projections often extend to 2100, but stakeholders primarily need short-to medium-term forecasts that align with public policy timelines. Indicators on extreme impacts and risks are a strong demand of public actors, especially in the health and energy sectors. Additionally, since recent urban climate resources remain largely unseen by public actors, we recommend enhancing its dissemination through local institutes recognized by policymakers, such as urban planning agencies. In summary, this case study provided valuable insights into the key mechanisms required for effectively disseminating climate research to promote climate change adaptation. Practical informationThis study investigates how climate information could be better communicated and used by public stakeholders for decision-making, particularly in the case of adapting cities to climate change. Cities are indeed places with significant societal, economic and environmental importance and could be particularly impacted by the effects of climate change across various different sectors. Furthermore, urban areas are already subject to a phenomenon known as the urban heat island (UHI): with nighttime urban temperatures being a few degrees higher than the surrounding countryside. The intensity of the UHI can vary according to different factors depending on the city itself, the geographical context, and weather conditions. The effect is particularly exacerbated during heatwaves (Li and Bou-Zeid, 2013) which can worsen the consequence
Convergence rates for an Adaptive Biasing Potential scheme from a Wasserstein optimization perspective
No full text52 pagesFree-energy-based adaptive biasing methods, such as Metadynamics, the Adaptive Biasing Force (ABF) and their variants, are enhanced sampling algorithms widely used in molecular simulations. Although their efficiency has been empirically acknowledged for decades, providing theoretical insights via a quantitative convergence analysis is a difficult problem, in particular for the kinetic Langevin diffusion, which is non-reversible and hypocoercive. We obtain the first exponential convergence result for such a process, in an idealized setting where the dynamics can be associated with a mean-field non-linear flow on the space of probability measures. A key of the analysis is the interpretation of the (idealized) algorithm as the gradient descent of a suitable functional over the space of probability distributions
Modelling evapotranspiration in urban green stormwater infrastructures: Importance of sensitivity analysis and calibration strategies with a hydrological model
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Models confirm that recent European wildfires are exacerbated by anthropogenic climate change
No full textClimate change is an ongoing process that is modifying weather patterns and influencing weather phenomena and extreme events such as heatwaves, droughts, and floods. This paper investigates whether climate change can also play a role in enhancing wildfires by focusing on a set of three recent wildfires in Europe. We employ the concept of analogues to assess the influence of climate change on the atmospheric conditions underlying wildfire development monitored through the fire weather index, by comparing past and present atmospheric patterns similar to those that occurred during the wildfire. Our analysis focuses on both reanalysis data and high-resolution regional climate models to verify the observed changes and provide future projections. Our findings show that climate change has altered critical factors supporting wildfire development, such as wind patterns, temperature, and humidity. The results from our sample of three events point out that climate change has increased wildfire hazards in Europe, which is projected to further increase for similar fire weather conditions in the future
Transfert de microplastiques via le réseau d’assainissement unitaire : des dépôts au sein du réseau aux rejets urbains de temps de pluie
No full textInternational audienceAlthough it is recognized in the literature that urban wastewater carries a significant load of microplastics (MP), the contamination of deposits in sewer networks and combined sewer overflows (CSO) has remained unexplored until now, despite potentially significant contamination. Concentrations of between 5 × 103 and 178 × 103 particles/kg of dry sediment were observed in deposits, indicating that some of the microplastics carried by wastewater settle. Irrespective of the polymer considered, the sedimentation of some of the microplastics within the network could be linked to wastewater flow conditions, but also to interactions with other particles in the wastewater, and/or to the formation of hetero-aggregates with other mineral or organic particles, whether or not coated with biofilm. These phenomena lead to the formation of a large stock within the network, and the associated risk of transfer during rainy events due to the resuspension of these sediments. MP concentrations in the CSO fluctuate between 67 and 392 particles/L, and no clear relationship between MP concentration and the proportion of wastewater or stormwater or with other physico-chemical parameters, was demonstrated. This suggests that the contamination of CSO is complex and may depend on many other factors. Among these factors, the resuspension of deposits within the network could play a key role. Considering that 21 million m3 of CSO are discharged into the Seine every year and the minimum and maximum concentrations, an annual flow of particles was estimated at between 1.4 × 1012 and 8.2 × 1012 particles/year, a relatively large flow compared with the flows discharged by wastewater treatment plants (from 2,4 × 1011 to 2,3 × 1013 particles/an or downstream of the Paris conurbation (1,1 × 1013 particles/an).S’il est reconnu dans la littérature que les eaux résiduaires urbaines véhiculent une charge en microplastiques (MP) importante, la contamination des dépôts de réseaux d’assainissement et des rejets urbains de temps de pluie restait jusqu’alors inexplorée, malgré une contamination potentiellement importante. Les concentrations observées pour les dépôts (entre 5 × 103 et 178 × 103 particules/kg de sédiment sec) témoignent en effet qu’une partie des microplastiques véhiculés par les eaux usées peut sédimenter. Indépendamment du polymère considéré, la sédimentation d’une partie des microplastiques au sein du réseau pourrait être liée aux conditions d’écoulement, mais aussi aux interactions avec les autres particules des eaux usées, et/ou à la formation d’hétéro-agrégats avec d’autres particules minérales ou organiques revêtues ou non de biofilm. Ces phénomènes conduisent à la formation d’un stock important au sein du réseau, et au risque associé de transfert lors d’événements pluvieux en raison de la remise en suspension de ces sédiments. Les concentrations en MP dans les rejets urbains de temps de pluie (RUTP) fluctuent entre 67 et 392 particules/L, et aucune relation claire entre la concentration en MP et la proportion d’eaux usées ou d’eaux pluviales dans les RUTP, ni avec d’autres paramètres physico-chimiques n’a pu être mise en évidence. Cela suggère que la contamination des MP dans les RUTP est complexe et peut dépendre de nombreux autres facteurs. Parmi ces facteurs, la remise en suspension des dépôts au sein du réseau pourrait jouer un rôle clé. En considérant que 21 millions de m3 de RUTP sont déversés en Seine chaque année et les concentrations minimales et maximales, un flux annuel de particules a été estimé entre 1,4 et 8,2 × 1012 particules/an, flux relativement conséquent au regard des flux rejetés par les stations d’épuration (entre 2,4 × 1011 et 2,3 × 1013 particules/an) ou à l’aval de l’agglomération parisienne (1,1 × 1013 particules/an)
Three-dimensional numerical modeling of sediment transport in a highly turbid estuary with pronounced seasonal variations
No full text(IF 3.5;Q2)International audienceSimulating sediment dynamics in a large and energetic estuary system remains challenging, primarily due to the spatial and temporal complexities of the interaction between flow and sediment transport, especially for sand-mud mixtures. This study uses a three-dimensional (3D) numerical model, based on the open TELEMAC system, to investigate the dynamics of suspended sediment concentration (SSC) in the Gironde Estuary, a complex estuarine environment characterized by an estuarine turbidity maximum (ETM) and significant variations in river discharge. The main contributions of this study include addressing the challenges of coupling bed friction with sediment transport of the sand-mud mixture for feedback on bed roughness and bottom depth changes and the ability of the model to capture the migration of ETM from high to low flow. Additionally, the current study analyzes the ability of the model to capture the migration of ETM from high to low flow, and it utilizes a calibration strategy that minimizes parameters by using in situ data and encompassing hydroemorpho-sedimentary interactions. A sensitivity analysis was done using different settling velocity approaches and sediment classes to establish an optimal model configuration and the uncertainty associated with the reduced model parameterization is discussed. The model satisfactorily reproduces the hydrodynamic features, particularly when the hydro-sedimentary feedbacks are taken into account, the seasonal trend of SSC, springneap variations, and the development of a well-defined ETM. The selection of a specific formulation for the settling velocity influences the location and magnitude of ETM. The van Leussen formula not only predicts a broad movement of ETM from high to low river flow, but also predicts high turbidity for extended periods during low river flow. Conversely, two empirical formulas from Le Hir and Defontaine predicted the highest turbidity during neap tides but sediment losses during prolonged simulations. The results of this study contribute to a deeper understanding of sediment dynamics in the Gironde Estuary, providing valuable information for future estuarine modeling and management
The Transformation of the Patient-Physician Relationship in Telemedicine: Sociological Approach in Dermatology
No full textInternational audienceBackground: In 1999, the inaugural editorial of the Journal of Medical Internet Research underscored the imperative to evaluate the patient-physician relationship amid the advent of internet-driven medical practices. Even at that nascent stage, views diverged sharply. Some anticipated that novel communication technologies would enhance closeness between physicians and patients. Others feared these technologies signaled a degradation of interpersonal connections and a dehumanization of health care experiences. Objective: Reflecting on years of developments, we consider this an opportune moment to reassess transformations in patient-physician interactions, in which notions of distance and proximity are redefined in some unexpected ways. Methods: In this paper, we intend to focus on teleconsultation and tele-expertise, the two most commonly used services in our field, dermatology. To navigate these changes, a sociological perspective inspired by Isaac Joseph’s theoretical framework has been adopted. Joseph posits that service-oriented relationships depend on 3 core skill sets among participants: technical, civic, and contract management. In medicine, these translate to the clinical, social, and contractual aspects of care. Telemedicine programs introduce significant shifts and adaptations across these dimensions. Results: A primary challenge in telemedicine is the absence of comprehensive sensory information, a crucial component of traditional medical assessments. This article discusses how such technical alterations impact medical practice and necessitate a redistribution of roles. Telemedicine is not merely about adapting existing technical skills; it also demands new competencies, often referred to as “invisible work,” to make telemedicine work. Beyond its clinical dimensions, the therapeutic relationship is inherently social. It involves sending signals that confer respect and recognition of the other as a person. A common concern is that telemedicine might lead to reification, that is, turning human patients into objects to serve researchers and physicians, and although extensive literature suggests that physicians develop various strategies to mitigate this, other studies indicate an increased risk of reification in constrained contexts. Contract management skills consist of the parties involved reaching an agreement on the purpose of the service-related relationship and its practical applications. In telemedicine, this may involve reminding the patient that not everything can be done remotely. Conclusions: Through this analysis of the three components of the service relationship as defined by Joseph, we have highlighted the profound changes affecting the physician-patient relationship in the context of telemedicine. Dehumanization is an inherent risk in any medical health care partnership, regardless of whether patient care is delivered face-to-face or at a distance. While some studies have clearly documented the dehumanizing tendency of some telemedicine practices, telemedicine itself is neither reifying nor dehumanizing. The organizational arrangements, the context of work activities, the modalities of use in situ and the types of technological devices used are all contributing factors in defining the level of humanization in remote health care interactions
Strategic Fertility, Education Choices, and Conflicts in Deeply Divided Societies
No full textInternational audienceFertility becomes a strategic choice for minorities when having a larger share of the population helps to increase power. If parents invest resources to educate their children, then raising fertility for strategic reasons might be at the cost of future human capital. We dispel this view using census data from several developing countries. We show that religious and ethnic minorities in Indonesia, China, and Malaysia tend to invest more in both education and fertility compared to larger groups. Solving for the Nash equilibrium of an appropriation game between two groups with education and fertility being prescribed as group-specific behavioral norms, we offer a rationale for the observed patterns provided that human capital is an important input to appropriation
Faster than real-time, phase-resolving, data-driven model of wave propagation and wave–structure interaction
No full textInternational audienceA machine learning time-series prediction approach is proposed for wave propagation and wave load prediction. Under unidirectional wave conditions and variable bathymetry, given a wave gauge upstream, a model is shown to reproduce wave elevation or wave forces downstream under irregular steep and either non-breaking or breaking conditions. Attempts to perform the opposite calculation, predicting upstream conditions from downstream measurements, results in higher error, likely due to information loss under breaking conditions. For choice of machine learning approach, comparisons show that the Time-series Dense Encoder (TiDE) approach results in a good balance between model complexity, stability, computational time, and error. Over a flat bottom, time-series of wave elevation can be predicted up to 10 wavelengths away, though with a degraded accuracy compared to shorter distances. Similar results are shown for time-series of forces on a vertical cylinder, showing better results than a simple Morison approach, as used in engineering tools such as OpenFAST, but with a similarly fast computational time. Generalizations show that training on irregular wave data permit extrapolations to periodic wave cases. Finally, the same method also is also demonstrated at field-scale, comparing results between two offshore buoys
A hypocoercivity-exploiting stabilised finite element method for Kolmogorov equation
No full textInternational audienceWe propose a new stabilised finite element method for the classical Kolmogorov equation. The latter serves as a basic model problem for large classes of kinetic-type equations and, crucially, is characterised by degenerate diffusion. The stabilisation is constructed so that the resulting method admits a \emph{numerical hypocoercivity} property, analogous to the corresponding property of the PDE problem. More specifically, the stabilisation is constructed so that spectral gap is possible in the resulting ``stronger-than-energy'' stabilisation norm, despite the degenerate nature of the diffusion in Kolmogorov, thereby the method has a provably robust behaviour as the ``time'' variable goes to infinity. We consider both a spatially discrete version of the stabilised finite element method and a fully discrete version, with the time discretisation realised by discontinuous Galerkin timestepping. Both stability and a priori error bounds are proven in all cases. Numerical experiments verify the theoretical findings