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Les limites de la décolonisation d'une organisation humanitaire internationale - La "décolonialité" comme principe?
No full textInternational audienceIn 2025, the proportion of international staff from the Global South (and Africa in particular) within the humanitarian organization Médecins Sans Frontières (MSF) reached almost 50%. By changing the relationship to time, authority, abuse, management and gender, this “southernization” of staff has led to internal tensions and criticism. Based on participant observation and semi-structured interviews, we examine the possibility of decolonizing aid by assessing the extent to which these new members can break away from relations of domination and/or propose their own ways of thinking and acting.En 2025, la part du personnel international issue du Sud Global (et en particulier d'Afrique) au sein de l'organisation humanitaire Médecins Sans Frontières (MSF) a atteint près de 50%. En changeant le rapport au temps, à l'autorité, aux abus, au management ou au genre, cette « sudisation » du personnel génère tensions et critiques internes. À partir d'une observation participante et d'entretiens semi-directifs, nous interrogeons la possibilité d'une décolonisation de l'aide en évaluant dans quelle mesure ces nouveaux membres peuvent se départir des rapports de domination et/ou proposer leurs propres façons de penser et d'agir
Digging deeper into the impacts of different soil water systems on the date palm root architecture and associated fungal communities
No full textInternational audienceIn arid regions, excessive water use threatens agricultural sustainability and overall livelihoods. It is essential to minimize water consumption to address these issues. Date palm ( Phoenix dactylifera L.) is an emblematic crop of arid regions and a major water consumer. Tailoring current irrigation systems into new, water-efficient systems could help cope with the water consumption of this crop. Microbial communities associated with plants are essential for agricultural sustainability and could improve the water use efficiency in regions threatened by water scarcity. These communities should thus be seriously taken into account when adapting agrosystems to the current global change setting. However, no information is presently available on the effects of these modifications on date palm microbial communities. This study highlights the impact of different soil water systems (flooding and drip irrigation, natural conditions and abandoned farms) on date palm root fungal communities at different soil depths. The findings revealed that the soil water systems had a marked impact on fungal communities and that drip irrigation reduced the fungal diversity but increased the abundance of arbuscular mycorrhizal fungi. We showed that these effects were similar at all sampling depths. Finally, as the root architecture is a major determinant of water uptake, we reveal different behaviors of the root architecture under these different soil water systems to 160 cm depth. The findings of this study give new insights into the date palm root architecture and associated fungal communities, particularly in the context of the water availability crisis, which drives the adaptation of agricultural systems
Mixed-mode deformation in a rock bridge between two fault segments
No full textInternational audienceAnalyzing how fracture networks develop from preexisting isolated fault segments in immature faults may provide knowledge of the preparation process leading to fault growth and dynamic rupture. We reproduce this process experimentally using triaxial compression experiments coupled with time-lapse in-situ synchrotron X-ray tomography in Westerly granite core samples (10 mm diameter, 20 mm height) that contain two parallel notches oriented at 30 • with respect to the axis of the cylinder. We conducted the experiments at room temperature with a constant confining pressure of 20 MPa. We image microfracture development, characterize the microphysical processes of damage and fault growth in an intact rock bridge between the notches, and analyze the evolution of fractures oriented at 0 • -17 • (extensile) and 17 • -32 • (shear) as the rock approached failure. We also elucidate the strain localization process in the deforming rock using digital volume correlation. Our study offers a detailed comparison of microfracture and strain field development during fault growth.Results indicate that the rock bridge between the notches becomes damaged with a damage rate and a fracture rate diverging as the rock approaches macroscopic failure. Immediately preceding failure, shear fractures dominate the fracture networks. DVC analysis showed that the deformation process is mixed-mode, accommodated by dilation and shear strain, with the shear strains being more localized than the dilation. Furthermore, regions of high dilative strain host both extensile and shear fractures. These findings provide valuable insights into the fault growth process within an intact rock bridge between two fault segments in nature, demonstrating how mixed-mode deformation facilitates fault maturation.</div
Non‐Covalent Immobilization of Chiral Rhodium Catalysts on Carbon Nanotubes for Asymmetric Hydrogenation
No full textInternational audienceSupported chiral catalysts were prepared by ionic anchoring of two cationic rhodium complexes ( A and B ) onto functionalized carbon nanotubes (CNTs). The immobilization of the Rh complexes was done by applying two ionic anchoring strategies: i) electrostatic interaction with the negatively charged surface of carboxylate‐functionalized CNTs (CNT-COO-); ii) electrostatic interaction through a heteropoly acid (HPA) spacer previously grafted at the CNTs surface (CNT‐HPA). The characterization of the obtained CNT-COO-@complex A , CNT-COO-@complex B , CNT‐HPA@complex A , and CNT‐HPA@complex B materials by ICP, TEM and XPS showed the successful anchoring of the Rh complexes onto the supports. The HPA spacer was found to increase the catalyst's stability and to limit the effect of the CNT surface on the catalytic performances of the immobilized Rh complexes. CNT‐HPA@complexes performed the hydrogenation of dimethyl itaconate into methyl succinate with high conversions (83–100 %) and good enantioselectivities (58–63 %). The recyclability tests showed the catalysts were less active but still enantioselective after recycling
Early Zanclean coarse-grained deltas of southern France as terrestrial analogs to jezero western delta
No full textInternational audienceSince its landing in February 2021 and until the end of 2024, the Perseverance rover of the Mars 2020 mission has acquired observations on the western sedimentary fan of Jezero crater. First remotely, and then in-situ, these data have been useful to confirm the formation of the fan as a Gilbert-type delta, fed by water inputs from Neretva Vallis [1-4]. While the extensive data acquired with the rover allows to finely study the facies and geometries of the delta, some questions could be solved with help from a more external point of view. In that, we here propose terrestrial analogs to the Jezero delta to observe and compare mechanisms that led to the morphologies now preserved on Mars. We focus our attention on coarsegrained, barely lithified Gilbert-delta systems from the Early Zanclean period (~5 Ma, Early Pliocene) in southern France that could offer such analogies
Weather Shocks and the Optimal Policy Mix in a Climate-Vulnerable Economy
No full textUsing data from a selection of Latin American countries affected by El Niño-Southern Oscillation climate phenomena, we observe that extreme weather events can be highly disruptive for an economy, particularly in the agricultural sector, while also giving rise to inflationary pressures. Motivated by these findings, this paper examines the optimal stabilization policies for a climate-vulnerable economy with two segmented sectors: agriculture (producing food) and manufacturing. In response to climate disasters affecting agriculture, it is found to be optimal to increase fiscal transfers to farmers while maintaining core inflation at its target level. Deviating from the optimal policy mix results in smaller welfare losses as long as core inflation remains stabilized
Interaction Between Plants Through Litter Input in Mangrove Succession in the Red River Delta
No full textInternational audienceAims: Dominant or pioneer species litter decomposition was found to be involved in the recruitment of following species during succession in terrestrial plant communities, while knowledge remains scarce in wetland forests such as mangroves. Our study evaluated the influence of pioneer species leaf litter decomposition on (i) the settlement success of species following them or not in the natural succession and (ii) on soil characteristics.Location: Red River Delta, Vietnam.Methods: We set up an in situ experiment in mesocosms that followed the survival and growth of three species (Kandelia obovata, Aegiceras corniculatum, and Rhizophora stylosa) planted in soils of Avicennia marina or Sonneratia caseolaris, with or without leaf litter addition for 203 days. Soil nutrient contents were determined at the beginning and end of the experiment, and their metabolic fingerprints were compared using an untargeted metabolomic approach to highlight potential allelochemicals when a phytotoxic effect was observed.Results: Seedling response to litter addition was species-specific, which can be linked to their successional status. K. obovata was most affected by litter addition, showing better growth with both litter types. Meanwhile, A. marina litter substantially decreased survival rates by 50% for K. obovata and 33% for R. stylosa, suggesting a strategy to delay its replacement by these species through the release of phytotoxic decomposition by-products. Metabolic fingerprints of A. marina soils planted with K. obovata showed no shift in global chemical composition, but 12 features were found significantly more abundant in the presence of litter. Putative annotations revealed sulfur-containing metabolites, which are probable products of organic matter sulfurization, a frequently occurring process in mangrove sediments. These unusual compounds may act as allelochemicals and should be further assessed.Conclusions: Our findings suggest that allelopathic processes through litter decomposition may be at play in mangrove community assembly and could be a tool for restoration purposes
Contrasting trends of the ocean CO<sub>2</sub> sink and pH in the agulhas current system and the Mozambique basin, south-western Indian ocean (1963–2023)
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The Land Surface Interactions with the Atmosphere over the Iberian Semi-Arid Environment (LIAISE) field campaign
No full textInternational audienceOne of the greatest challenges facing environmental science is to better understand the impacts of predicted future changes in the terrestrial hydrological cycle. It has been recognized that human activities play a key role and must therefore be considered in future climate simulations. The representation of anthropization in land surface schemes within global earth system models is at a relatively nascent stage and must be improved for more accurate future projections of water resources. The understanding of the impact of anthropogenic processes has been hampered by the lack of consistent and extensive observations. Here, we present the Land surface Interactions with the Atmosphere over the Iberian Semi-arid Environment (LIAISE) project field campaign which brought together ground-based (surface energy budget estimated at 7 sites, 269 radio soundings made at 2 sites and multiple remote sensing instruments for profiling the lower atmosphere), airborne measurements (3 airplanes and numerous drones measuring surface and atmospheric properties) and satellite data (to derive estimates of irrigation timing, soil moisture, evapotranspiration and surfacetemperature) to improve our understanding of key natural and anthropogenic land processes and boundarylayer feedbacks. The study area is in the Ebro basin of northeastern Spain in a hot, dry Mediterranean climate,with a sharp demarcation between a vast intensively irrigated region and a much drier rainfed zone to the east.Analysis of the observations reveal strong surface heterogeneities of evapotranspiration within the irrigatedzone (differences upwards of approximately 7 mm day-1 between fields), linked to the crop type, vegetationphenology and soil moisture, all of which were modulated by irrigation. The significant surface flux differencesbetween the irrigated and rainfed zones were found to result in strongly contrasting atmospheric boundarylayer properties (between 2 supersites separated by 14 km) extending upwards through the lowest several kmof the atmosphere
Temporal dynamics of copepod taxa and trophic groups in a long-term time series in the NW-Mediterranean Sea
No full textInternational audienceAbstract In the context of structural and functional changes in the pelagic environment, and the oligotrophication and the temperature increase of the North Western Mediterranean, this study analyses a 17-year time series (2006–2022) of copepod temporal variability in the Bay of Marseille. Mesozooplankton was sampled bimonthly (0–55 m) together with biotic and abiotic parameters. This study focuses on the temporal dynamics and ecological niches of copepod taxa and trophic groups. In the Bay of Marseille, herbivorous copepods, Clausocalanus–Paracalanus–Ctenocalanus–Pseudocalanus, dominated the community in abundance. From taxa realized niches, we identified that temperature and trophic conditions drove the seasonal and interannual dynamics of copepods. During the summer months of recent years, the increasing oligotrophication and warming of the seawater favoured carnivorous copepods. A shift in the copepod community structure since the mid-2010s was demonstrated, with a decrease in total copepod abundance and reduced dominance of spring copepod taxa. The trophic group dynamics were mostly driven by a few dominant taxa in each group. Recent environmental conditions favoured increases in the abundance of two warm-water affinity species (Corycaeidae and Temora stylifera) and were unfavourable to a cold-water affinity species (Calanus helgolandicus)