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GNSS spoofing in conflict zones disrupts wildlife tracking and hampers research and conservation efforts
No full textInternational audienceIn war and conflict zones, the jamming of Global Navigation Satellite System (GNNS) signals by military forces disrupts the tracking of tagged animals, and has increased in frequency following the recent escalation of conflicts in Eastern Europe and the Middle East. Such disruption to data collection strongly hampers research into the protection and conservation of endangered animals
Isotopic Compositions of Modern Seawater at the Mariana and Yap Trenches
No full textInternational audienc
Évaluation des propriétés anti-inflammatoires de molécules naturelles biosourcées et de synthèse bio-inspirées
No full textChronic inflammatory diseases represent a major health concern, with their incidence steadily increasing. Unfortunately, current therapies remain insufficient to offer hope for disease remission. The search for new anti-inflammatory molecules, combined with a deeper understanding of inflammatory mechanisms—such as extracellular matrix remodeling—will help identify new and relevant therapeutic targets. The objectives of my thesis were to establish a macrophage-based model and evaluate the anti-inflammatory properties of natural (oligosaccharide) and bio-inspired (semi-synthetic and synthetic) molecules. The effects of these molecules were confirmed by measuring the production of inflammatory markers such as IL-6 and TNF-α, assessing the activation of inflammatory signaling pathways (ERK, JNK, p38, and Akt), and using in vivo mouse models. Notably, we highlighted the anti-inflammatory properties of pharmaco-modulated flavones and their mechanism of action in the treatment of chronic pain, as well as oligosaccharides derived from λ-carrageenan for the treatment of psoriasis. In particular, these oligosaccharides appear to regulate the expression of enzymes involved in extracellular matrix remodeling, such as metalloproteases and heparanase 1. Additionally, we conducted a literature review on the role of heparanases (1 and 2) in cutaneous inflammatory processes. Overall, my work has identified novel anti-inflammatory molecules, contributed to the study of heparanases in skin inflammation, and paved the way for the development of new therapeutic solutions for chronic inflammatory diseases. These findings demonstrate that this cellular model is a valuable tool for exploring the anti-inflammatory mechanisms of molecules, which can subsequently be studied in various inflammatory contexts.Les maladies inflammatoires chroniques constituent un problème de santé majeur, dont l’incidence est en constante augmentation. Malheureusement, les thérapies actuelles sont encore insuffisantes pour espérer une rémission de ces maladies. La recherche de nouvelles molécules anti-inflammatoires, associée à une meilleure compréhension des mécanismes inflammatoires, comme le remodelage de la matrice extracellulaire, permettra de mettre en évidence de nouvelles cibles thérapeutiques pertinentes. Les objectifs de mon travail de thèse ont été de mettre en place un modèle basé sur les macrophages et d’évaluer les propriétés anti-inflammatoires de molécules naturelles (oligosaccharide) et bio-inspirées (semi-synthétique et de synthèse). Les effets des molécules ont été confirmés en mesurant la production de marqueurs inflammatoires comme l’IL-6 et le TNF-alpha, l’activation de voies de signalisation inflammatoires ERK, JNK, p38, Akt et l’utilisation de modèles murins in vivo. Nous avons notamment mis en évidence les propriétés anti-inflammatoires des flavones pharmaco-modulées et leur mécanisme d'action dans le traitement de la douleur chronique, ainsi que d’oligosaccharides dérivés du λ-carraghénane dans le traitement du psoriasis. Ces derniers semblent notamment contrôler l’expression d’enzymes impliquées dans le processus de remodelage de la matrice extracellulaire, comme les métalloprotéases et l’héparanase 1. Enfin, nous avons réalisé une étude bibliographique sur le rôle des héparanases (1 et 2) dans les processus inflammatoires cutanés. Dans l’ensemble, mes travaux ont permis de mettre en évidence de nouvelles molécules anti-inflammatoires, de contribuer à l’étude des héparanases dans l’inflammation cutanée et ils ouvrent la porte au développement et à l’application de nouvelles solutions thérapeutiques pour les maladies inflammatoires chroniques. Ces résultats démontrent que ce modèle cellulaire est un outil pertinent pour explorer les mécanismes anti-inflammatoires des molécules, qui peuvent ensuite être étudiées dans une variété de contextes inflammatoires
Insight on the global water distribution in opal considering its bi-component nature
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Earlymost Cambrian Monomorphichnus scratch marks, Rozel Cape, Normandy (NW France)
No full textInternational audienceVarious ichnofossils have been discovered in the Terreneuvian (earlymost Cambrian) deposits of the Rozel Cape, in Normandy (NW France). In addition to fine horizontal trace fossils (e.g., Archaeonassa, Psammichnites, Helminthopsis) and also complex treptichnid burrow (e.g., Treptichnus pedum), the bed surfaces share clusters of striations preserved in concave epirelief. Each cluster contains 3 to 18 straight to slightly sigmoidal striations. According to these characteristics, these trace fossils can be referred to the ichnogenus Monomorphichnus. These ichnofossils are generally considered as arthropod displacement traces, and are often related to trilobites. However, the earlymost Cambrian beds of the Rozel Cape are older than the first trilobites-bearing deposits in the same region, and outcropping more than 10 km to the south, at Saint-Jean-de-la-Rivière. The presence of Monomorphichnus is the first evidence of arthropods, possibly trilobites, in the early Cambrian ecosystems preserved in the sedimentary series of Normandy, and in the Armorican Massif. Sedimentological characteristics of the deposits (ripple marks, syneresis cracks) correspond to a shallow marine shelf environment, with a variable hydrodynamic activity in the intertidal zone
Changes in continental weathering regimes inhibited global marine deoxygenation during the Paleocene-Eocene thermal maximum
No full textInternational audienceThe moderate impact of rapid global warming on oceanic redox and biodiversity during the Paleocene-Eocene thermal maximum (PETM; ~55.9 Ma) contrasts with other hyperthermal events in Earth's history, and remains mostly unexplained. Here, we use lithium isotope (δ7Li) proxy and Earth system model simulations to reconstruct continental weathering regimes during the PETM. Negative δ7 Li excursions of 3-4‰ in shallow-marine carbonates suggests globally increased erosion rates and decreased weathering intensities. Further, large negative δ7Li excursions of 4-5‰ in siliciclastic successions reflect enhanced accumulation of detrital clays exhumed from previous clay-rich sedimentary rocks, rather than those from weathering of igneous rocks. Changes in continental weathering regimes and associated flux of nutrients to oceans provide an explanation to the muted increase in oceanic anoxia and overall biodiversity loss during the PETM. The concomitant increases in physical erosion and clay delivery also enhanced organic carbon burial efficiency, permitting rapid return of global climate to pre-perturbation state
Eruption Column Modeling of Explosive Volcanism on Venus
No full textInternational audienceVolcanism on Venus has never been directly observed, but several measurements indicate present‐day activity. Volcanism could potentially play a role in climatic processes on Venus, especially in the sulfur cycle like on Earth. Observation of volcanic activity is the primary objective of future Venus spacecraft. However, there are many unknowns regarding its Venusian characteristics, like the condition at the vent, the volatile content and composition. Past modeling efforts have only studied explosive volcanic plume propagation over a limited range of flow parameters at the vent and in an idealized Venus atmospheric configuration. We propose to use the 1D FPLUME volcanic plume model in a realistic Venusian environment. In similar Venusian conditions, the height of the plume is consistent with past modeling. The present study shows that explosive volcanism would preferably reach 15 km of altitude. Under certain conditions, plumes are able to reach the VenSpec‐H tropospheric altitude range of observations and even the 45 km cloud floor. For the first time, the impact of wind was quantified, and the super‐rotating winds have a substantial impact by plume‐bending of reducing the height of plumes. Contrary to the Earth, the atmospheric heat capacity depends greatly on temperature, and will disadvantage lower plumes and allow larger plumes to propagate at higher altitudes. The high latitude atmospheric environment, due to the thermal profile and weaker winds, is favorable to plumes reaching higher altitudes
Relations entre paramètres ESR/OSL et éléments traces dans des quartz : que nous disent les roches?
No full textInternational audienceLes rivières sont des objets complexes et extrêmement sensibles aux variations climatiques. L’étude des mouvements de leur lit, l’historique de leur débit, de leurs flux de sédiments sont autant d’indices qui permettent d’en savoir plus sur l’histoire de notre climat et de prédire leur évolution future. Les méthodes de datation paléodosimétriques sont des outils indispensables permettant de tracer les mouvements de sédiments quaternaires et de mieux comprendre les dynamiques des rivières. Deux méthodes communément utilisées sont l’OSL (Optically Stimulated Luminescence) et l’ESR (Electronic Spin Resonance) qui utilisent les propriétés de luminescence et paramagnétiques du quartz. Des travaux récents ont également démontré l’intérêt de ces deux méthodes dans l’étude de la provenance de sédiments, la présence de centres paramagnétiques ou luminescents auxquels sont sensibles l’OSL et l’ESR étant intimement liées aux conditions de formations du quartz et à son histoire (déformation, métamorphisme, hydrothermalisme, etc.), et pouvant possiblement évoluer pendant les processus d’érosion et de transport des sédiments.Si peu d’études discutent le sujet, le lien entre pétrographie et signaux OSL/ESR semble crucial pour améliorer notre compréhension des phénomènes paramagnétiques et luminescents et notre confiance dans les datations.Cette étude se concentre sur des échantillons de roches constitutives du bassin versant du Strengbach (Vosges). Les quartz extraits de leur gangue rocheuse ont été analysés par OSL, ESR et LA-ICP-MS. Des analyses LA-ICP-MS ont également été faites sur des lames minces des roches afin de pouvoir intégrer les spécificités structurales des quartz à leur analyse chimique. Une emphase particulière a été mise sur les concentrations en Li, Al et Ti, les plus abondant dans le quartz, associés aux principaux centres ESR et suspectés avoir un rôle majeur sur le signal OSL. Nos résultats mettent en avant des signatures en éléments traces spécifiques entre quartz de différentes genèses ainsi que des différences significatives de comportements ESR et OSL. Les relations entre éléments traces et signaux ESR ou OSL ne sont cependant pas simples impliquant que l’association entre un élément et un centre luminescent ou paramagnétique n’est pas directe. L’histoire métamorphique et tectonique des roches semble également jouer un rôle important
Modelling extensive green roof CO 2 exchanges in the Town Energy Balance urban canopy model
No full textInternational audienceGreen roofs are promoted to provide ecosystem services and to mitigate climate change in urban areas. This is largely due to their supposed benefits for biodiversity, rainwater management, evaporative cooling, and carbon sequestration. One scientific challenge is quantifying the various contributions of green roofs using reliable methods. In this context, the green roof module already running in the Town Energy Balance urban canopy model for water and energy exchanges was improved by implementing CO2 fluxes and carbon sequestration potential. This parameterization combines the Interactions between Soil–Biosphere–Atmosphere (ISBA) photosynthesis, biomass, and soil respiration module with the green roof module in order to quantify the net CO2 amount emitted or fixed by the green roof over a time period. Measurement data from an extensive non-irrigated Sedum green roof located at Berlin Brandenburg (BER) Airport in Germany from 2016 to 2020 are used to calibrate and evaluate the parameterization. Based on the 5 years of measurements, a sensitivity analysis is conducted to quantify the significance of selected parameterization parameters for the photosynthesis process, followed by a calibration over the most important parameters and an evaluation. Results show good agreement of the simulated leaf area index and CO2 fluxes with in situ observations, with good diurnal, seasonal, and inter-annual variability, although the model tends to be overly responsive on the day-to-day variability. The model effectively reproduces net ecosystem exchange, which provides a reliable estimation of the annual carbon sequestration. These results are encouraging in terms of quantifying the potential of carbon sequestration by green roofs and open up the possibility of applying the new parameterization on a city-wide scale to evaluate green roof scenarios
Sédimentologie et enregistrement sédimentaire du Crétacé supérieur du Haut Atlas occidental Marocain
No full textInternational audienceLate Cretaceous sediments frequently record the paleoenvironmental and paleogeographic changes, which precede the Tertiary Alpine orogeny. The age of the Late Cretaceous deposits of the Moroccan Western High Atlas, has been refined thanks to few paleontological findings and to chemostratigraphical (13C) correlations. Coniacian and Santonian shallow marine deposits are dominated by the development of eustacy-controlled carbonate shelves, whereas Campanian and Maastrichtian deposition recorded mainly clastic deposits showing important facies and thickness variability, suggesting a tectonic instability. The appearance of sandstone beds and the fragmentation of the basin in the middle(?) Santonian (≈ 84 Ma) are interpreted as a result of a mild tectonic event. A significant tectonic event of Late Campanian age (≈ 77-74 Ma) is marked by the deposition of 50-100m-thick nearshore sandstones, by clastic dykes and mild angular unconformities in the South and by a probable widespread hiatus to the North. The latter area may have been uplifted by at least a few tens of meters. A new, major tectonic event of middle(?) Maastrichtian age (≈ 70 Ma) is marked, specially to the South and West of the study area, by deposition of up to 300 m-thick shallow marine sandstones, associated with slumps, breccias, clastic dykes and erosions. The absence or reduction of Paleocene deposits in the study area seems to be rather related to eustatic low sea level