The BIOMASP+ project on biosphere-atmosphere exchanges and their role in air pollution in the subtropical megacity of São Paulo: motivations, methods and preliminary observations

International audienceAir pollution, especially in urban areas, is the result of a complex mixture of natural and anthropogenic emissions and their atmospheric processing. It causes millions of premature deaths worldwide and affects plant metabolism, which in turn alters the emissions of Biogenic Volatile Organic Compound (BVOCs) by plants. By taking the subtropical Metropolitan Area of São Paulo (MASP) as a natural laboratory, the BIOMASP+ project (BIOsphere-atmosphere interactions in the Metropolitan Area of São Paulo - plus) a ims to evaluate the interplay between the biosphere and secondary pollution (ozone and SOA formation and aging). The Brazilian Atlantic Forest (Mata Atlântica) is the target ecosystem as the fifth biodiversity hotspot in the world. Here we present the scientific motivations of the project, its methodology and the preliminary observations from the Special Observation Periods of year 2023 (SOP1, 2, 3 and 4). BIOMASP+ is (i) integrative, by combining in-situ/remote/laboratory observations andmodeling, (ii) multidisciplinary, addressing micrometeorology, urban climate, atmospheric chemistry and biology. The project involves multiple nested scales: from leaf to above-canopy levels, from very short time (microseconds) to multi-year scale, from few millimeters (turbulence scale) to synoptic scale. In particular, the experimental effort relies on the implementation of two contrasting supersites (primary forest and urban forest) with a 30-m and 20-m flux towers, respectively, and a variety of state-of-the-art instruments. Ambient observations and the quantification of BVOC emissions have highlighted the complex interactions between meteorology, atmospheric composition of pollution, biogenic emissions of representative remnants of the Atlantic Forest and anthropogenic emissions

Analysis of the abundance and impacts of volatile organic compounds across Europe

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A systematic review of thermal manikins for thermal comfort and IAQ assessment: design trade-offs and a capability-based development framework

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Multimodal FM–SEM Dataset with Millimetre-Scale Field of View for Bundle-Scale Porosity and Impregnation Quantification in Woven GFRP/PP Composites

International audienceA curated multimodal microscopy dataset is presented for statistical quantification of through-thickness, bundle-scale impregnation and porosity—defined as non-filled regions within bundle cross-sections—in woven glass-fibre/polypropylene (GF/PP) laminates. The dataset spans three controlled compaction ratios (Cr = 0%, 30%, 41%), providing a structured basis for investigating processing–microstructure relationships in thermoplastic composites and addressing limitations of 2D single-modality analyses of partially impregnated materials. Large-area cross-sections were prepared post-processing using a fluorescence-enriched epoxy mount and a multi-step polishing protocol tailored to partially impregnated thermoplastics, then imaged by fluorescence microscopy (FM), polarized light microscopy (PLM) and backscattered-electron scanning electron microscopy (SEM–BSE). Overlapping tiles were stitched into millimetre-scale extended-field images that still resolve individual filaments and were rigidly registered to form aligned FM/PLM/SEM stacks across the full laminate thickness. Detailed procedures for sample manufacturing, surface preparation, polishing and quantitative analysis are provided in a companion research article by the same authors [1]. The core quantitative products are extended-field FM and SEM images with associated five-class Random Forest segmentation maps, trained on image-derived intensity features to distinguish phase- and porosity-related classes (including glass fibres, matrix and void-rich regions), while PLM primarily documents surface state and polishing quality. For bundle-scale analysis, more than 15 complete fibre bundles oriented perpendicularly to the polishing plane (0°-oriented) are extracted and systematically labelled per extended-filed image. For each bundle, the dataset provides paired FM/SEM crops, corresponding segmented images, and binary masks for void-limited masks, bundle outlines and the glass-fibre phase. The companion research article reports per-bundle quantitative metrics, whereas the present data paper describes the dataset structure and known limitations, including large image sizes, residual SEM brightness drift, exclusion of bundles with pronounced stitching artefacts, and the non-linear response of dye infiltration to porosity. The full dataset, including raw and processed image products, is available in the public repository Recherche Data Gouv [2]. To the best of current knowledge, this is the first publicly available FM/SEM multimodal dataset at single-fibre resolution over millimetre-scale fields of view for thermoplastic composite microstructures, providing a benchmark resource for registration, segmentation and impregnation-quantification methods

The Radial Spanning Tree is straight in all dimensions

The Radial Spanning Tree (RST) in dimension $d\geq2$ is a random geometric graph constructed on a homogeneous Poisson point process $\N$ in $\R^d$ augmented by the origin, with edges connecting each $x\in\N$ to the nearest point $y\in\N\cup\{0\}$ that lies closer to $0$ than $x$, with respect to the Euclidean distance. By construction, it forms almost surely a tree rooted at $0$. The RST was introduced in 2007 by Baccelli and Bordenave, who investigated straightness, a deterministic property introduced by Howard and Newman in 2001, to derive information about the asymptotic directions of infinite branches. They proved that the RST is almost surely straight in dimension $2$, which directly implies that all infinite branches are asymptotically directed, every possibility is attained, and directions reached by multiple infinite branches form a dense subset. However, their approach relies crucially on planarity, preventing any straightforward extension to higher dimensions. In this paper, we close this gap by proving that the RST is almost surely straight in any dimension, thereby obtaining the same consequences for the behaviour of infinite branches. Our approach resolves the key barriers in the study of the RST, notably those posed by the complex dependency structure combined with the radial nature of the model, and especially beyond the planar setting. It relies on tools developed for the analysis of the Directed Spanning Forest, a closely related model, including recent progress by the author in 2025. Specifically, a key contribution of this work is the construction of a suitable renewal-type decomposition of RST paths. Leveraging this decomposition together with classical concentration inequalities, we show that RST paths cannot deviate far from straight lines and derive straightness

Imaginer les futurs de l’éducation : Un cas d’adaptation collective des ateliers du futur.

International audienceDans le contexte de l’éducation post-numérique, cette étude présente le processus de création collective d’un guide d’animation pour la conduite d’Ateliers du Futur avec des acteurs et actrices de l’éducation. L’objectif est d’identifier les défis rencontrés sur le terrain et de co-construire collectivement des futurs désirables, au-delà des imaginaires technocentrés dominants. La méthode suit quatre phases : (1) conception initiale du guide sur la base de la méthode des Ateliers du Futur ; (2) validation et relecture par des experts ; (3) pré-test avec un groupe hétérogène d’enseignant·e·s ; et (4) mise en œuvre des Ateliers du Futur auprès des acteurs et actrices de l’éducation. Chaque phase a conduit à des modifications du guide. Les résultats montrent que la méthode permet une réflexion critique sur les enjeux systémiques des institutions d’enseignement, stimule la créativité collective et favorise la coopération entre participant·e·s. Les limites identifiées concernent notamment le temps disponible, l’hétérogénéité des profils, et la difficulté à adopter des formats créatifs non conventionnels en contexte professionnel. L’étude met en lumière la nécessité d’un guide flexible pouvant être adapté selon les contextes. Cette recherche souligne la pertinence de la méthode pour des démarches participatives, à condition d’en adapter les usages aux publics visés et de prévoir des prolongements concrets

Decomposition of O3 onto natural Gobi dust: From uptake to surface reactivity

International audienceBeyond synthetic metal oxides, this work investigates natural mineral dust as a material of interest for O3 uptake and decomposition. Ozone and Gobi dust interactions are addressed combining gas phase and adsorbed phase approach. It allows for determining: (i) the drivers of O3 decomposition process on Gobi and (ii) surface reactions and mechanism. First, the steady catalytic decomposition of ozone onto Gobi is explored on a large O3 concentration range: 20 ppb − 10 ppm, with steady uptake coefficients ranging from 2.6 x 10-9 to 6.2 x 10-8. If moisture (20 % RH) does not impact initial uptake of O3 it is evidenced to hinder the steady state behavior. Cyclic surface regeneration evidences that: (i) wet air flushing restores initial uptake properties, and (ii) mild thermal treatment (150 °C) restores the complete uptake process. Along O3 decomposition, adsorbed phase monitoring using DRIFT allows for identification and dynamic monitoring of specific IR bands on Gobi surface. Oxide and peroxide surface species are created. To meet environmental conditions, the role of water on surface groups created by O3 uptake is addressed through water molecule uptake experiments. Finally, a five-step mechanism is proposed to describe uptake and surface reactivity of O3 on Gobi dust. This work provides a comprehensive evaluation of the surface properties and reactivity of Gobi dust towards O3, valuable for atmospheric, geocatalytic and plasma-catalytic processes

Uptake of atmospheric pollutants on road asphalt pavements: an underestimated sink in urban environments

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Unleashing the Power of Gradual Patterns for Explainable AI

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Stabilization of compressed earth bricks (CEB) using alkali-activated glass powder: A sustainable binder approach

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