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Multiscale analysis of existing actual evapotranspiration products over agropastoral Sahel
No full textInternational audienceUnderstanding the spatiotemporal variability of actual evapotranspiration (ET) is a critical issue for better water resources management from plot to basin scale. It is particularly true in the Sahelian region which is very vulnerable in terms of water and agricultural resources, but also very scarcely monitored. This study aims to improve understanding of ET in Sahelian agrosystems by comparing twenty ET products and collections on two areas in Central Senegal and South-Western Niger: Breathing Earth System Simulation (BESS), Derive Optimal Linear Combination Evapotranspiration (DOLCE) v2.1 and v3.0, ERA5 and ERA5-Land, FLUXCOM-RS, Global Land Data Assimilation System (GLDAS) on Noah and Catchment Land Surface Model (CLSM), Global Land Evaporation: the Amsterdam Methodology (GLEAM) v3.5a, v3.5b, v3.6a and v3.6b, Modern-Era Retrospective analysis for Research and Applications v2 (MERRA-2), MODIS Global Evapotranspiration products (MOD16/MYD16), Penman-Monteith Leuning version 2 (PML_V2) v0.1 and v0.1.7, Reliability Ensemble Averaging (REA), Simplified Surface Energy Balance for operational applications (SSEBop) and Water Productivity through Open access of Remotely sensed derived data (WaPOR). In order to assess the abilities and drawbacks of each product, a multi-scale analysis is first performed at local scale with different temporal aggregation levels (daily, decadal, monthly). The best performing products, like GLEAM, MERRA-2 or GLDAS-Noah, have low spatial resolution (≥0.25°), but shows really good agreement with ET measurements (RMSE ∼ 0.5 mm.d-1, R2 ≥ 0.8). A multi-scale spatial analysis with different spatial aggregation levels (1, 10 and 25 km) is then performed on interannual composite maps of annual and seasonal ET. Results highlight the different spatiotemporal behaviour of all the products. Products such as ERA5-Land and PML_V2 0.1.7 stand out in this comparison as their higher resolution allows them to describe the spatial patterns of ET realistically and more precisely while having relatively good performances at local scale (RMSE ∼ 0.6 mm.d-1, R2 ≥ 0.7). Overall, the comparison highlights the need to consider soil moisture to accurately estimate ET in the Sahelian region, as the products considering it generally show better performances. It also points out the lack of a high quality and resolution ET product over the Sahel. Future satellite missions, as well as data fusion techniques, could help to fill up this gap and propose a reference product on Sahelian ecosystems
3D models related to the publication: Dental morphology evolution in early peratheriines, including a new morphologically cryptic species and findings on the largest early Eocene European metatherian: 3D models of Peratherium musivum and Pt. maximum (early Eocene, France)
No full textInternational audienceThis contribution contains the three-dimensional models of the most informative fossil material attributed to both Peratherium musivum Gernelle, 2024, and Peratherium maximum (Crochet, 1979), respectively from early and middle early Eocene French localities. These specimens, which document the emergence of the relatively large peratheriines, were analyzed and discussed in: Gernelle et al. ( 2024), Dental morphology evolution in early peratheriines, including a new morphologically cryptic species and findings on the largest early Eocene European metatherian
Evidence that genetic drift not adaptation drives fast‐Z and large‐Z effects in Ficedula flycatchers
No full textInternational audienceThe sex chromosomes have been hypothesized to play a key role in driving adaptation and speciation across many taxa. The reason for this is thought to be the hemizygosity of the heteromorphic part of sex chromosomes in the heterogametic sex, which exposes recessive mutations to natural and sexual selection. The exposure of recessive beneficial mutations increases their rate of fixation on the sex chromosomes, which results in a faster rate of evolution. In addition, genetic incompatibilities between sex‐linked loci are exposed faster in the genomic background of hybrids of divergent lineages, which makes sex chromosomes contribute disproportionately to reproductive isolation. However, in birds, which show a Z/W sex determination system, the role of adaptation versus genetic drift as the driving force of the faster differentiation of the Z chromosome ( fast‐Z effect) and the disproportionate role of the Z chromosome in reproductive isolation ( large‐Z effect) are still debated. Here, we address this debate in the bird genus Ficedula flycatchers based on population‐level whole‐genome sequencing data of six species. Our analysis provides evidence for both faster lineage sorting and reduced gene flow on the Z chromosome than the autosomes. However, these patterns appear to be driven primarily by the increased role of genetic drift on the Z chromosome, rather than an increased rate of adaptive evolution. Genomic scans of selective sweeps and fixed differences in fact suggest a reduced action of positive selection on the Z chromosome
Density-dependent network structuring within and across wild animal systems
No full textInternational audienceHigh population density should drive individuals to more frequently share space and interact, producing better-connected spatial and social networks. Despite this widely-held assumption, it remains unconfirmed how local density generally drives individuals’ positions within wild animal networks. We analysed 34 datasets of simultaneous spatial and social behaviour in >55,000 individual animals, spanning 28 species of fish, reptiles, birds, mammals, and insects. >80% of systems exhibited strongly positive relationships between local density and network centrality, providing broad empirical evidence that local density increases connectedness at the individual level. However, >75% of density-connectedness relationships were nonlinear, and density’s importance declined at higher values in >70% of systems, signifying saturating effects. Density’s effect was much stronger and less saturating for spatial than social networks, suggesting population density drives individuals to become disproportionately spatially connected rather than socially. These findings reveal fundamental trends underlying societal structuring, with widespread behavioural, ecological, and evolutionary implications
A Continuity of Shariʿa: Political Authority and Homicide in the Nineteenth Century, written by Brian Wright
No full textInternational audienc
A comprehensive review on TiO2-based heterogeneous photocatalytic technologies for emerging pollutants removal from water and wastewater: From engineering aspects to modeling approaches
No full textInternational audienceThe increasing presence of emerging pollutants (EPs) in water poses significant environmental and health risks, necessitating effective treatment solutions. Originating from industrial, agricultural, and domestic sources, these contaminants threaten ecological and public health, underscoring the urgent need for innovative and efficient treatment methods. TiO 2 -based 2 semiconductor photocatalysts have emerged as a promising approach for the degradation of EPs, leveraging their unique band structures and heterojunction schemes. However, few studies have examined the synergistic effects of operating conditions on these contaminants, representing a key knowledge gap in the field. This review addresses this gap by exploring recent trends in TiO 2 -driven heterogeneous photocatalysis for water and wastewater treatment, with an emphasis on photoreactor setups and configurations. Challenges in scaling up these photoreactors are also discussed. Furthermore, Machine Learning (ML) models play a crucial role in developing predictive frameworks for complex processes, highlighting intricate temporal dynamics essential for understanding EPs behavior. This capability integrates seamlessly with Computational Fluid Dynamics (CFD) modeling, which is also addressed in this review. Together, these approaches illustrate how CFD can simulate the degradation of EPs by effectively coupling chemical kinetics, radiative transfer, and hydrodynamics in both suspended and immobilized photocatalysts. By elucidating the synergy between ML and CFD models, this study offers new insights into overcoming traditional limitations in photocatalytic process design and optimizing operating conditions. Finally, this review presents recommendations for future directions and insights on optimizing and modeling photocatalytic processes.</div
Questioning calculation and interpretation of fluorescence indices in natural waters studies
No full textInternational audienceFluorescence indices are particularly well adapted to characterize dissolved organic matter. In environmental studies, the three most often used fluorescence indices are the Fluorescence index (FI), the Humification index (HIX) and the Biological index (BIX). The present paper aims to discuss 4 limitations in the actual use of fluorescence indices: (i) difference between indices values calculated from interpolated and non-interpolated excitation wavelengths; (ii) misfit between the areas and wavelengths from the index definition (HIX, FI, BIX) and the samples (peaks location and curve shape) related to environmental context (e.g. pH, living conditions of organic matter decomposers); (iii) the potential to rethink the 2D-based indices thanks to 3D matrices; (iv) the incidence of recent improvement in organic matter degradation knowledge on the fluorescence indices interpretation. These limitations are illustrated with different types of water samples coming from three different open access datasets: karst groundwaters from Serene et al. (2024), marine waters from Drozdova et al. (2019) and surface water from Sgroi et al. (2019). These results draw the attention of fluorescence indices users to unsupervised calculation and interpretation of 2D-based fluorescence indices. It also greatly encourages the rethinking of fluorescence indices using EEM (Excitation Emission Matrices) in order to adapt the calculation to each purpose and study context and to limit the generalisation of indices interpretation to organic matter structure
Unbalanced L1 optimal transport for vector valued measures and application to Full Waveform Inversion
No full textInternational audienceOptimal transport has recently started to be successfully employed to define misfit or loss functions in inverse problems. However, it is a problem intrinsically defined for positive (probability) measures and therefore strategies are needed for its applications in more general settings of interest. In this paper we introduce an unbalanced optimal transport problem for vector valued measures starting from the optimal transport. By lifting data in a self-dual cone of a higher dimensional vector space, we show that one can recover a meaningful transport problem. We show that the favorable computational complexity of the problem, an advantage compared to other formulations of optimal transport, is inherited by our vector extension. We consider both a one-homogeneous and a two-homogeneous penalization for the imbalance of mass, the latter being potentially relevant for applications to physics based problems. In particular, we demonstrate the potential of our strategy for full waveform inversion, an inverse problem for high resolution seismic imaging
A European aerosol phenomenology – 9: Light absorption properties of carbonaceous aerosol particles across surface Europe
No full textInternational audienceCarbonaceous aerosols (CA), composed of black carbon (BC) and organic matter (OM), significantly impact the climate. Light absorption properties of CA, particularly of BC and brown carbon (BrC), are crucial due to their contribution to global and regional warming. We present the absorption properties of BC (b) and BrC (b) inferred using Aethalometer data from 44 European sites covering different environments (traffic (TR), urban (UB), suburban (SUB), regional background (RB) and mountain (M)). Absorption coefficients showed a clear relationship with station setting decreasing as follows: TR > UB > SUB > RB > M, with exceptions. The contribution of b to total absorption (b), i.e. %Abs, was lower at traffic sites (11–20 %), exceeding 30 % at some SUB and RB sites. Low AAE values were observed at TR sites, due to the dominance of internal combustion emissions, and at some remote RB/M sites, likely due to the lack of proximity to BrC sources, insufficient secondary processes generating BrC or the effect of photobleaching during transport. Higher bAbs and AAE were observed in Central/Eastern Europe compared to Western/Northern Europe, due to higher coal and biomass burning emissions in the east. Seasonal analysis showed increased b, b}_{Abs,BrC}_{BrC}_{Abs,BC}_{Abs,BrC}_{BrC}_{BrC}_{Abs,BrC}$ and AAE increased, suggesting a shift in CA composition, with a relative increase in BrC over BC. This study provides a unique dataset to assess the BrC effects on climate and confirms that BrC can contribute significantly to UV–VIS radiation presenting highly variable absorption properties in Europe
The potential of sap conduction in the olive tree is linked to aridity conditions of the main cultivation area of varieties and allow to uncover their sensitivity to ongoing climate change
No full textInternational audienceHighlights: • In the olive tree, a pattern of wood vessel enlargement with branch age is shown. • This pattern varies according to the aridity conditions of the main cultivation area. • Some varieties cannot adjust their sap conduction potential when aridity increases. • Results raise questions about selection of tolerant varieties to low water resources.Abstract: This study examines the impact of drought, and by extension potential water scarcity, on the potential of sap conduction in the olive tree, the emblematic fruit tree of the Mediterranean Basin. To understand adaptation of sap conduction potential of varieties concerning drought, we focus on wood anatomical traits in trees cultivated in the conservatory orchard of the 'Conservatoire Botanique National Méditerranéen' (Porquerolles, France) and others from their main cultivation area. Leveraging branch diameter as a key factor influencing anatomical traits, we model density of vessels (DVS) and lumen area of vessels in transverse section (LAV) variation based on branch diameter using regression analyses. Our results show that the pattern of increase in LAV cannot be considered to be dependent on the biogeography and evolutionary history of varieties. But, it is significantly linked to the aridity conditions of the main cultivation area of these varieties. In the perspective of a future drastic increase in aridity, results point to the potential incapacity of varieties from non-irrigated semi-arid zones, to produce vessels large enough to transport sap to the leafy parts of branches, and other varieties from the northern margins of olive distribution area, to modulate conduction in terms of efficiencysafety balance. While some varieties exhibit a robust or moderately plastic phenotype, showing negligible variations in conduction potential with changing aridity in growing conditions, these results concern about the sustainability and future viability of some varieties. More broadly, they raise questions about the olive cultivation sector's resilience in the face of intensifying water stress