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Integrating Transient Hydrogeology Models for Enhanced Interpretation of Geophysical Data in the Vadose Zone
No full textInternational audienceQuantifying water and heat fluxes at the interface between surface water (SW), groundwater (GW), and the vadose zone (VZ) is critical for sustainable water and energy resource management under global change. Direct field measurements are challenging because SW–GW exchanges depend on initial and boundary conditions and the spatial distribution of hydrofacies, which are often poorly constrained. Usually, these fluxes are estimated by calibrating models using classical data like hydraulic heads and river discharge. But it is well known that these data did not get enough information to constrain these fluxes. To overcome the lack of direct in situ data, de Marsily et al., (2005) and Schilling et al., (2019) suggested to couple the classical observations with unconventional data such as the geophysical surveys, for instance successfully applied in the context of SW-GW exchanges by Dangeard et al., (2021). Binley et al., (2015), in their comprehensive review, highlighted the robustness of geophysical methods for imaging subsurface structures and estimating saturation profiles, reinforcing their role as essential tools for characterizing vadose zone processes.This study develops a transient, process-based hydrogeophysical forward model that integrates hydrological and geophysical processes. The geophysical methods used in this study are electrical resistivity tomography (ERT), seismic methods, and heat tracing, applied as complementary approaches to characterize vadose zone dynamics and link hydrological processes to geophysical data. The hydrological model (Rivière et al., 2020) rigorously solves Richards’ equation coupled with heat transport—simulating variably saturated water and thermal fluxes in porous media under transient conditions—and was validated with experimental and field data to explore the variability of saturated flow and heat fluxes. The seismic model, based on Solazzi et al., (2021) uses the Hertz-Mindlin contact theory combined with the Biot-Gassmann model and simulates the influence of capillary suction with a transient method. The electrical model uses the Waxman-Smits petrophysical law to quantify electrical conductivity of the soil. The outputs of the hydrological model are coupled with geophysical forward models to compute synthetic geophysical models (P and S wave velocity, electrical resistivity) and associated data (more particularly surface wave phase velocity, apparent electrical resistivity); as well as heat tracing signals). The synthetic case considered in this study is a 1D soil column, subjected to seasonal variations in precipitation and temperature, to analyze the resulting dynamics and their geophysical data.Testing this integrated model under typical spring conditions in the Paris Basin demonstrates:The added value of transient modeling for interpreting geophysical data. Sensitivity of seismic and electrical responses to soil saturation and pressure changes, even without water table fluctuations. The influence of past infiltration events on geophysical survey interpretation. This approach provides new insights into VZ functioning and strengthens the link between hydrological processes and geophysical signatures, paving the way for improved characterization of subsurface dynamics under global changes
Probabilistic Heat Transfer Coupled For Improved Urban Climate Predictions
No full textOur cities are getting hotter, particularly during heatwaves, which impacts our comfort and energy bills. It is crucial to predict how heat moves through complex urban areas, from buildings to streets, in order to design cooler, more sustainable cities. However, current methods struggle to cope with the complexity of urban landscapes. This paper introduces a revolutionary computer model that addresses this challenge. Using the Monte Carlo technique, our model can accurately simulate combined heat transfer in complex city geometry, accounting for precise thermal and solar radiative heat transfers. Unlike previous models, ours can handle intricate city designs with ease, enabling us to understand the combined effects of conduction, convection and radiation. We have demonstrated the high accuracy of our model, even in detailed 3D city environments. For example, we used it to simulate a heatwave, demonstrating that planting trees can significantly cool streets during the day, although they might slightly reduce night-time radiative cooling. This new tool will empower researchers to improve the coupling of building energy models with urban climate models, and ultimately create cities that are more comfortable and energy-efficient for all.</div
Impact of charge transfer inefficiency on transit light curves: A correction strategy for PLATO
No full textInternational audienceContext. PLATO is designed to detect Earth-sized exoplanets orbiting solar-type stars and to measure their radii (relative to the star radii) with an accuracy better than 2% via the transit method. Charge transfer inefficiency (CTI), a by-product of radiation damage to charge-coupled devices (CCDs), can jeopardise this accuracy constraint and therefore must be corrected to reach scientific requirements.Aims. We assessed and quantified the impact of CTI on transit depth measurements. Our objective was to demonstrate the need for CTI correction and to develop a correction strategy that restores CTI-biased transit depths with an acceptable residual within the accuracy budget.Methods. Using a calibration dataset generated with PLATOSim to simulate a realistic stellar field, we modelled the parallel overscan signal as the sum of exponential decays and used least-squares fitting to infer the number of trap species and initial estimates for the release times (τr,k). Smearing was then modelled with an exponential-plus-constant function and removed on a column-wise basis. We modelled the spatial variation in the trap density with a quadratic polynomial function of the radial distance from the centre of the focal plane. The polynomial coefficients (ap,k) of this model, the well-fill power index (β), and the release times (τr,k) were subsequently adjusted via an iterative application of the extended pixel edge response method combined with a CTI correction algorithm. This yielded the final calibration model that underpins our correction strategy.Results. In the worst-case scenario (8-year mission, high CTI impact zone), we found that CTI induced a bias of approximately 4% in the measured transit depth. The polynomial coefficients from our trap density model were then used to correct the CTI-affected transit depths. Our correction reduced the bias to a residual of 0.06%, which is comfortably within PLATO’s accuracy requirements.Conclusions. We quantified the CTI-induced bias in transit depth measurements and implemented a calibration strategy that incorporates spatial variations in trap density. From the calibrated parameters, we derived a correction scheme that brought the photometric measurements within PLATO’s noise budget, ensuring that the mission’s precision requirements are met
Bumblebees are the most efficient pollinators of raspberry and strawberry in urban environments
No full textInternational audiencePollinators are essential for crop pollination, but pollinators differ in their pollination efficiency. In urban areas, environmental filters such as soil sealing or the urban heat island lead to biotic homogenisation of pollinator communities, with generalist species being favoured while specialist species are filtered out. Therefore, efficient pollinators may be excluded from urban areas. In the context of the development of urban agriculture, urban areas require pollination by efficient pollinators. Here, we ask whether pollinators sustained in urban environments are equally efficient, and whether urbanisation impacts the efficiency of pollinators delivering pollination services.Using strawberry and raspberry as experimental plants, we carried out single visit experiments over 2 years (2023 and 2024) in spring and autumn, to assess pollination efficiency in densely urbanised and suburban sites in the region of Paris (France). We measured fruit mass, malformation and seed set of fruits which developed from flowers having received a single visit from a pollinator.3. We found that bumblebees were more efficient than honeybees as pollinators of raspberry, but not strawberry, as measured by fruit mass.Bumblebees were also more efficient than small and large solitary bees for pollinating strawberry, and more efficient than large solitary bees for pollinating raspberry. These differences were detected on mass for strawberries, and on mass, seed set and fruit malformation for raspberries.Practical implication: Environmental filters in urban environments tend to favour few generalist pollinator species. On one hand, these environments support honeybees, which we found were not necessarily the most efficient. On the other hand, wild pollinators, in particular bumblebees, were more efficient than honeybees for pollination of strawberry and raspberry. Thus, urban conservation strategies should focus on promoting these wild and efficient pollinators by planting beneficial plant species in flower beds and providing nesting habitats for ground nesting pollinators. This would promote diverse and efficient pollinators and thus enhance pollination services for urban agriculture
Un essai de stratigraphie urbaine d’Oran du Moyen Âge à la conquête française
No full textInternational audienceمدينة وهران غنية بتاريخ طويل وحافل بثقافات وتقاليد مختلفة، وتحتفظ بالقليل من الشواهد الدالة على تنظيمهاالفضائي في العصور الوسطى أو العصر الحديث. أدى تطوير التخطيط العمراني الحديث أو حتى المعاصر إلى طمستخطيط العصور الوسطى بالكامل تقريبًا. ومع ذلك، فإن القراءة الدقيقة للمصادر العربية والأوروبية الرئيسية معتحليل مختلف الخرائط والوثائق المتوفرة في الأرشيف الإسباني والفرنسي تمكن من تسليط الضوء على التغييرات فيالتنظيم الفضائي للمدينة والعثور على موضع مباني القرون الوسطى الأكثر رمزية وتطور المدينة على مر القرونRiche d’une longue histoire mouvementée sous des pouvoirs de culture et de traditions différentes, la ville d’Oran conserve peu de témoins de son organisation spatiale médiévale ou d’époque moderne. Le développement d’un urbanisme plus récent voire contemporain a effacé presque totalement la disposition médiévale. Toutefois, une lecture précise des principales sources arabes et européennes jointe à une analyse des différents cartes et représentations disponibles dans les archives espagnoles et françaises permettent de mettre en lumière les changements ou des permanences dans l’organisation spatiale de la ville et de retrouver, avec une stratigraphie historique, l’emplacement d’édifices médiévaux les plus emblématiques et le développement de la ville au long des siècles
Jusqu’à la garde
No full textInternational audienceSadi Carnot est né en 1837, Santo Geronimo Caserio en 1873. L’inversion de deux chiffres croise-t-elle un destin ? Le premier est le rejeton d’une de ces familles pour qui l’histoire politique du siècle en passe de s’écouler a été un terrain de jeu ; petit-fils de révolutionnaire, fils de républicain, Sadi est passé par l’école Polytechnique avant que la guerre contre la Prusse l’amène à son tour sur le terrain politique. Échappe-t-on à un destin familial ? Fils d’une famille pauvre de Lombardie, orphelin de père, le second est envoyé en apprentissage à 12 ans à Milan ; figure archétypale des misères de la révolution industrielle, son engagement l’a traîné sur le chemin de l’exil, en Suisse puis en France. Dans la vague des attentats, Santo est porté pendant deux jours par une obsession que nul obstacle, nul doute, ne peuvent contenir. Car c’est la volonté forcenée du second qui lie leurs noms dans l’histoire, où ils apparaissent comme deux images inversées d’une République qui voyait s’avancer le XXe siècle à l’horizon, ébranlée par les scandales et les attentats
“Toward an Alternative to the EU Migration Policy: Hospitality as Ethics”, communication durant le workshop Ethics at Border : Solidarity, Responsability and Relationality, O.P. Jindal Global University, New Delhi, 16-17 mars 2026.
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Unlocking the Microbiome-Metabolome Nexus for Innovative One-Health Solution
No full textMicrobial communities, encompassing a vast taxonomic diversity, are fundamental to ecosystem integrity, biogeochemical cycles, and the health of humans, animals, and plants, along the One Health concept. A major scientific goal is to understand how these complex consortia function, interact, and adapt to environmental changes. Microbial meta-metabolomics has emerged as a powerful approach to tackle this by characterizing the collective metabolome of an entire community, linking it to environmental conditions and biogeochemical processes. It captures the functional output of both cultivable and uncultivable organisms, tracing chemical interactions and the impact of environmental perturbations. However, while meta-metabolomics provides a comprehensive snapshot of community chemistry, it alone cannot decipher the precise dynamics of which microorganisms are producing metabolites, when, where, and why. To address this, we propose the Microbial Metabolomics Framework (MiMetWork). This novel framework expands beyond descriptive meta-metabolomics to integrate spatial and temporal metabolomic characterizations with other omics data and phenotyping techniques. MiMetWork employs high-throughput screening of various microbiome components—from single cells to complex communities—under controlled conditions to elucidate ecophysiological functions and interaction mechanisms. By combining untargeted and targeted metabolomic datasets with microbial composition and pathway information, MiMetWork aims to build causal models of microbiome function and adaptation. This review outlines how this integrative framework leverages technological advances to elucidate microbiome interactions and functional responses across human, animal, and environmental niches, thereby addressing critical research gaps and enhancing our predictive understanding of microbiomes within the One Health paradigm
Évolution et impact de la pratique amatrice de la paléontologie aux falaises des vaches noires (normandie, France)
No full textSince the 18th century, the Vaches Noires cliffs have yielded a large number of fossils, which have been described in numerous publications. Most of these fossils were collected by amateurs and then made available to professional researchers. Here we explore the literature concerning the Vaches Noires paleontology in order to highlight and quantify the impact of amateurs on collecting and preserving Jurassic and Cretaceous fossils from this emblematic locality in Normandy. Over the last 270 years, about 350 scientific publications have been published about the Vaches Noires, more than 85 % of them concerning palaeontology. More than half of that literature was produced during the last 30 years, mainly on vertebrates, ammonites, echinoderms and bivalves. Depending on the model that is used, amateur palaeontologists contributed, through their discoveries, to 50 to 70 % of the papers published by professional palaeontologists, which reflects their extremely strong implications and emphasises the synergy between both communities.Depuis le 18 e siècle, les falaises des Vaches Noires ont livré une grande quantité de fossiles qui ont fait l'objet de nombreuses publications. La majorité de ces fossiles a été collectée par des amateurs, puis mis à disposition des chercheurs. Nous explorons ici la littérature sur la paléontologie des Vaches Noires afin de mettre en lumière et quantifier l'impact des amateurs sur la collecte et la préservation des fossiles jurassiques et crétacés de ce gisement emblématique de Normandie. Sur les 270 dernières années, environ 350 publications scientifiques sont parues sur les Vaches Noires, plus de 85 % concernant la paléontologie. Près de la moitié de la littérature a été produite ces trente dernières années, en majorité sur les vertébrés, les ammonites, les échinodermes et les bivalves. Suivant le modèle utilisé, les paléontologues amateurs contribuent, par leurs découvertes, à 50 à 70 % des articles publiés par les paléontologues professionnels, ce qui traduit une implication extrêmement forte de leur part et souligne la synergie entre les deux communautés