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Are urban areas better environmentally managed than countries ?
No full textGovernment entities are crucial in implementing effective mitigation and adaptation strategies to cope with climate change. This article introduces an innovative quantitative composite index to assess environmental performance across the city and country levels: a Deterioration of Environmental Performance Index (DEPI). This new index provides valuable and objective insights into the sustainability of territorial development strategies. This article aims to understand how local and national governments address environmental challenges by leveraging these metrics. We compute the annual index evolution for ten countries from 2001 to 2020. Our findings reveal that, compared to baseline levels, environmentally harmful outcomes generally decrease more significantly (or increase less sharply) over time. In addition, countries tend to outperform their cities in managing five critical environmental impacts: air pollution, river flooding, coastal flooding, forest fires, and heatwaves
Computational study of OH, NH2-functionalized iron-doped tetraphenylporphyrin as a photocatalyst for CO2 reduction to C1 fuels
No full textInternational audienceThe photocatalytic CO2 reduction reaction (CO2RR) has attracted considerable attention as a promising strategy for sustainable fuel production. Recent efforts have focused on enhancing the catalytic performance of iron-doped tetraphenylporphyrin (Fe-TPP) through chemical modification. This work has systematically investigated the hydroxyl, amino-functionalized Fe-TPP (Fe-OHTPP and Fe-NH2TPP) as a photocatalyst for CO2RR using density functional theory (DFT) calculations. The HOMO–LUMO analysis reveals that the Fe center acts as an electronic bridge, promoting efficient charge transfer. To explore the photocatalytic mechanism, we examined the most favorable adsorption configurations of key intermediates and evaluated their reaction and Gibbs free energies. The calculated limiting potential of Fe-NH2TPP is −0.24 eV, and the adsorption energy of the C1 product CH4 molecule is −0.05 eV for both surfaces, indicating that the catalyst remains stable and reusable after product release. Overall, the results demonstrate that Fe-OHTPP and Fe-NH2TPP catalysts thermodynamically favors C1 production, providing mechanistic insights of CO2 conversion into value-added chemical fuels via hydroxyl, amino-functionalized Fe-TPP photocatalysts
RibPull: Implicit Occupancy Fields and Medial Axis Extraction for CT Ribcage Scans
No full textInternational audienceWe present RibPull, a methodology that utilizes implicit occupancy fields to bridge computational geometry and medical imaging. Implicit 3D representations use continuous functions that handle sparse and noisy data more effectively than discrete methods. While voxel grids are standard for medical imaging, they suffer from resolution limitations, topological information loss, and inefficient handling of sparsity. Coordinate functions preserve complex geometrical information and represent a better solution for sparse data representation, while allowing for further morphological operations. Implicit scene representations enable neural networks to encode entire 3D scenes within their weights. The result is a continuous function that can implicitly compesate for sparse signals and infer further information about the 3D scene by passing any combination of 3D coordinates as input to the model. In this work, we use neural occupancy fields that predict whether a 3D point lies inside or outside an object to represent CT-scanned ribcages. We also apply a Laplacian-based contraction to extract the medial axis of the ribcage, thus demonstrating a geometrical operation that benefits greatly from continuous coordinate-based 3D scene representations versus voxel-based representations. We evaluate our methodology on 20 medical scans from the RibSeg dataset, which is itself an extension of the RibFrac dataset. We will release our code upon publication.</div
La peinture chinoise en douze notes illustrées et dix œuvres commentées
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Du héros solitaire à la signature commune : l’ambivalence d’une représentation collective dans la pratique des graphistes
No full textInternational audienceThis article examines the concept of collectivity within the practices and productions of graphic designers, with particular attention to the discourses and material forms of representation—such as signatures, iconography, and other visual markers—employed by various groups of practitioners from the second half of the 2Oth century to the present. These case studies are contextualized within a broader historical framework that traces the socio-professional transformations that have reshaped the field of graphic design over the past century.Cet article questionne la notion de collectif dans la pratique et les productions des graphistes en s’attachant aux discours et à la matérialité des représentations (signature, iconographie, etc.) de plusieurs regroupements de praticien·nes de la seconde moitié du XXe siècle à aujourd’hui, tout en les replaçant dans une histoire plus large des bouleversements socioprofessionnels subis par cette pratique depuis plus d’un siècle
Sustainable Nanocarbons via Biocatalysis of C-F Bond Cleavage by Electroactive Bacteria
No full textInternational audienceFluorographite is a promising starting material for the synthesis of graphene and graphene oxides via top-down exfoliation routes. C-F bonds in fluorographite can be chemically substituted to form graphene oxides with tuned surface chemistry. However, most defluorination routes reported proceed via fluorographene exfoliation from fluorographite followed by refluxing in organic solvents. Herein a one-pot, biogenic and aqueous route to graphene oxide nanomaterials directly from fluorographite with no pre-exfoliation step is demonstrated. Fluorographite incubation with the electroactive bacterial species Geobacter sulfurreducens yields water-dispersible graphene oxide quantum dots and partially-defluorinated graphene oxides as the main nanomaterial products in a single step. Biocatalysis at ambient temperature and pH proceeds through direct surface contact with bacteria through C-F bond cleavage, with fluorographite serving as the sole electron acceptor for exo-electrogenic respiration. This bioexfoliation strategy presents a sustainable and green synthetic route to functionalised carbon nanomaterials with tuneable size and surface properties under ambient conditions.</div
DUALF-D: Disentangled dual-hyperprior approach for light field image compression
No full textInternational audienceLight field (LF) imaging captures spatial and angular information, offering a 4D scene representation enabling enhanced visual understanding. However, high dimensionality and redundancy across spatial and angular domains present major challenges for compression, particularly where storage, transmission bandwidth, or processing latency are constrained. We present a novel Variational Autoencoder (VAE)-based framework that explicitly disentangles spatial and angular features using two parallel latent branches. Each branch is coupled with an independent hyperprior model, allowing more precise distribution estimation for entropy coding and finer rate-distortion control. This dual-hyperprior structure enables the network to adaptively compress spatial and angular information based on their unique statistical characteristics, improving coding efficiency. To further enhance latent feature specialization and promote disentanglement, we introduce a mutual information-based regularization term that minimizes redundancy between the two branches while preserving feature diversity. Unlike prior methods relying on covariance-based penalties prone to collapse, our information-theoretic regularizer provides more stable and interpretable latent separation. Experimental results on publicly available LF datasets demonstrate our method achieves strong compression performance, yielding an average BD-PSNR gain of 2.91 dB over HEVC and high compression ratios (e.g., 200:1). Additionally, our design enables fast inference, with a total end-to-end time over 19x faster than the JPEG Pleno standard, making it well-suited for real-time and bandwidth-sensitive applications. By jointly leveraging disentangled representation learning, dual-hyperprior modeling, and information-theoretic regularization, our approach offers a scalable, effective solution for practical light field image compression.</div
Areas susceptible to desertification in Brazil: An approach based on the frequency of annual aridity classes
No full textInternational audienceThe expansion of arid lands is one of the most critical environmental threats of the century, driven by climate change and unsustainable human activities. In Brazil, recent climatic shifts suggest an expansion of arid and semi-arid zones beyond the traditionally vulnerable Northeast region. While prior research has emphasized long-term climatological trends focused in that region, this study adopts non-stationary approaches to examine year-by-year aridity class frequencies from 1961 to 2020 across the entirety of Brazil. It also distinguishes the relative influence of precipitation (P) and potential evapotranspiration (PET) on observed aridity index (AI) changes. Our results reveal an expansion of roughly 30 % of dryland conditions across Brazil over the past 30 years, extending beyond the traditionally semi-arid Northeast into the Southeast, and an emerging hotspot in the Pantanal, potentially linked with larger scale South American aridization trends. The increasing annual frequency of arid and semi-arid classifications, particularly in emerging zones, suggests a persistent shift towards drier climates. This pattern seems to be driven primarily by declining P and secondarily by rising PET (temperature). By analyzing annual frequencies, we uncover a creeping aridity process, which directly converses with updated desertification risk assessments and climate adaptation strategies in Brazil, such as the ‘Brazilian Action Plan to Combat Desertification and Mitigate the Effects of Drought’
15N NMR study of protonation position determination in 2-(6-methoxynaphthalen-2-yl)vinyl diazine chromophores
No full textInternational audienceThe 1H-15N HMBC spectra were successfully used for protonation position determination in 4-[(E)-2-(6-methoxynaphthalen-2-yl)vinyl]pyrimidine (1), 2-[(E)-2-(6-methoxynaphthalen-2-yl)-vinyl]quinoxaline (2), 2-[(E)-2-(6-methoxynaphthalen-2-yl)vinyl]pyrazine (3), and 3-[(E)-2-(6-methoxynaphthalen-2-yl)vinyl]pyridazine (4). Mono protonation was proved. In three cases (compounds 1, 2 and 4) only one nitrogen was protonated while in pyrazine compound 3 the equilibrium between regioisomers was observed