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A New Lunar Crustal Thickness Model Constrained by Converted Seismic Waves Detected Beneath the Apollo Seismic Network
No full textInternational audienceAnalysis of conversions between compressional and shear waves is a workhorse method for constraining crustal and lithospheric structure on Earth; yet, such converted waves have not been unequivocally identified in seismic data from the largest events on the Moon, due to the highly scattered waveforms of shallow seismic events. We reanalyze the polarization attributes of waveforms recorded by the Apollo seismic network to identify signals with rectilinear particle motion below 1 Hz, arising from conversions across the crust-mantle boundary. Delay times of these converted waves are inverted to estimate crustal thickness and wavespeeds beneath the seismometers. Combined with gravimetric modeling, these new crustal thickness tie-points yield an updated lunar crustal model with an average thickness of 29-47 km. Unlike previous models, ours include explicit uncertainty estimates, offering critical context for future lunar missions, geophysical studies, and predicting 15-36 km crust at Schrödinger and 29-52 km at Artemis III sites.Plain Language Summary The Moon's crust holds key information about its formation, evolution, and surface processes. Using seismic data from the Apollo missions, we identified moonquake seismic signals arising from the boundary between the Moon's crust and mantle, allowing us to obtain new estimates of crustal thickness beneath the Apollo landing sites. These signals had previously been difficult to detect due to extensive scattering caused by the highly fractured and heterogeneous lunar crust. By integrating our seismic estimates with gravity and topography data, we developed an updated global map of the Moon's crustal thickness, revealing an average thickness of 29-47 km and providing uncertainty quantification not available in previous models. Our results provide vital insights into the Moon's interior structure and offer valuable guidance for future lunar exploration and sustainable human activities on the Moon.</p
Exploring the Isotopic Variation of Germanium in Earth’s mantle
No full textInternational audienceQuantifying Germanium (Ge) isotopic fractionation during Earth's formation requires an accurate estimation of the Ge isotope composition of silicate reservoirs, a challenge highlighted by previous studies1–4. Establishing a robust isotopic baseline for Earth’s mantle necessitates a detailed investigation of mantle-derived melts and their source rocks. Garnet, a key Ge host, has a pressure-dependent partition coefficient that significantly influences Ge systematics in Mid-Ocean Ridge Basalts (MORBs) and Ocean Island Basalts (OIBs)5,6. This pressure dependence may lead to measurable Ge isotopic fractionation during mantle melting, affecting both melts and residues.To better understand these effects, we have undertaken a large study (n > 60 samples) of different silicate reservoirs, significantly expanding upon the scarce mantle data reported so far1–3. We analyzed ultramafic mantle rocks, their mineral separates, and basalts from MORB and OIB settings. Germanium isotope ratios were measured using a Hydride Generation Introduction System coupled to the NeptunePlus MC-ICP-MS at CRPG Nancy. Mass bias is corrected by the sample-standard bracketing method to the standard NIST SRM 3120a, achieving a 2-sigma reproducibility better than 0.10 ‰ on δ74/70Ge with < 50 ng Ge consumed per triplicate analysis. Our new results explore potential variations in Ge isotope compositions, aiming to assess whether mantle lithology—particularly the presence of pyroxenites—plays a role in isotopic fractionation during mantle melting. By combining whole-rock and mineral-scale analyses, we evaluate how phase-specific partitioning may influence Ge isotope systematics, including whether residual garnet or other phases impart distinct isotopic signatures. These findings will refine our understanding of Ge behavior during mantle processes, improving our ability to assess Ge isotope variations in Earth’s mantle
Évaluation de la fonction rénale à l’âge de 4 à 6 ans dans une cohorte d’anciens grands prématurés
No full textBackground: Very preterm infants (VPI, < 32 weeks of gestation) are at increased risk of chronic kidney disease and long-term hypertension, due to incomplete nephrogenesis and early exposure to certain nephrotoxic agents. Biological abnormalities may precede clinical signs. This study assessed their frequency and blood pressure (BP) at school age in VPI, as well as associations with perinatal factors.Method: VPI born at Reunion Island university hospital who were followed-up for kidney function from birth were included. At ages 4–6, assessments included anthropometry, BP, plasma creatinine, cystatin C, urea, electrolytes, and urine albumin/creatinine ratio. Abnormalities were defined as eGFR <90 mL/min/1.73 m², macroalbuminuria, or microalbuminuria. Association with perinatal factors were analyzed using univariate and bivariate models.Results: Among 69 children included (mean age 5.1 years), 56.5% had a biological abnormality: 33.8% had low eGFR, 1.4% macroalbuminuria, 26.1% microalbuminuria. Systolic or diastolic BP ≥95th percentile was found in 10.1% and 8.7% respectively. No neonatal factor, including nutrition, was linked to renal abnormalities. High diastolic BP correlated with lower birth weight and Z-score, higher delta weight Z-score from birth to 36 weeks, and higher BMI at follow-up.Conclusion: Over half of GP had renal function abnormalities at school age, and nearly one-third had elevated BP. Early rapid weight gain appears linked to higher diastolic BP, underlining the need to monitor growth to prevent renal and cardiovascular risks.Contexte : Les enfants nés grands prématurés (GP, <32 semaines) présentent un risque accru de maladie rénale chronique et d’hypertension à long terme, lié à une néphrogénèse incomplète et à des expositions précoces à certains néphrotoxiques. Des anomalies biologiques peuvent précéder les signes cliniques. Cette étude a évalué leur fréquence et la pression artérielle (PA) à l’âge scolaire chez des GP, ainsi que leurs liens avec des facteurs périnataux.Méthode : Des GP nés au CHU Sud-Réunion avec suivi rénal dès la naissance étaient inclus. Entre 4 et 6 ans, les évaluations comprenaient mesures anthropométriques, PA, créatinine, cystatine C, urée, électrolytes et rapport albumine/créatinine urinaire. Les anomalies étaient définies par un DFGe <90 mL/min/1.73 m², une macroalbuminurie ou une microalbuminurie. Les liens avec les facteurs périnataux ont été analysés par modèles statistiques univariés et bivariés.Résultats : Parmi 69 enfants inclus (âge moyen 5.1 ans), 56.5 % avaient une anomalie biologique : 33.8 % un DFGe <90 mL/min/1.73 m², 1.4 % une macroalbuminurie, 26.1 % une microalbuminurie. Une PA systolique ou diastolique ≥95e percentile concernait respectivement 10.1 % et 8.7 % des enfants. Aucun facteur néonatal, y compris la nutrition, n’était associé aux anomalies rénales. Une PA diastolique élevée était corrélée à un poids et Z-score de naissance plus faibles, un delta Z-score du poids plus élevé a de la naissance à 36 semaines et un IMC plus haut au suivi.Conclusion : Plus de la moitié des enfants GP présentaient des anomalies rénales à l’âge scolaire, et près d’un tiers avaient une PA élevée. Un rattrapage pondéral rapide précoce semble lié à une PA diastolique élevée, soulignant l’importance du suivi de croissance pour prévenir risques rénaux et cardiovasculaires
3-D impedance networks simulate complex resistivity spectra of sand-pyrite-water mixtures
No full textInternational audienceCharacterizing ore deposits or mining dumps in terms of mineral content and grain size remains a challenge. Since the 1950s the induced polarization (IP) method has been successfully applied in ore prospecting. However, reliably interpreting field survey data requires comprehensive laboratory studies to establish a link between the IP parameters from empirical or phenomenological models and the type and quantity of ore minerals. In this study, we use numerical electrical networks to replicate the complex electrical resistivity spectra observed in experiments on sand-pyrite-water mixtures. A network consists of a 3-D assembly of resistors, representing the saturated pore space and leaky capacitors simulating the electrical behaviour of ore minerals. A sophisticated fitting procedure enables the precise determination of resistor and capacitor parameters, ultimately leading to strong agreement between measured and synthetic IP spectra. The results obtained from the 3-D network align well with the classical Pelton model, which is based on a simple equivalent circuit. Our findings indicate that the network's chargeability depends on the fraction of capacitors in the system (i.e. the number of capacitors divided by the number of capacitors and resistors), and that the Pelton time constant of the measured spectra is closely related to the resistor and capacitor parameters. We argue that a 3-D approach offers a more realistic framework, paving the way for future studies on the effects of ore grain size distribution, and the spatial arrangement of ore grains
Annual variations in Nepalese seismicity: b-values and seismicity rates
No full textInternational audienceSeasonal variations in Nepalese seismicity have been reported with varying degrees of confidence. We re-investigate these claims by analysing 20 yr of Nepalese seismicity before the 2015 Gorkha earthquake, as detected by the Nepalese national network, and focusing on earthquakes located along the eastern and central sections of the Nepalese Main Himalayan Thrust. Using several declustering techniques, we find no statistically robust evidence of seasonal seismicity in the studied record, regardless of magnitude threshold above completeness. This suggests that previously reported seasonality may be restricted to the western section of the Nepalese orogeny, may be an artefact, or may indicate that nucleation times of earthquakes are longer than the year. We also investigate potential annual variations in the Gutenberg–Richter b-value, given its recent observed modulation by transient stressing. Additionally, we use large-scale mass redistribution estimated from the monthly gravity field retrieved from the Gravity Recovery And Climate Experiment and Follow-On (GRACE/-FO) missions, to resolve stress variations at depth induced by transient surface loads. We find that the mean annual b-value peaks when seasonal Coulomb stress rates reach their minimum value at the height of the summer rainy season. When considering the combined effect of tectonic and seasonal loading, this corresponds to a recurring period of stress reversal, when Coulomb stress momentarily decreases. This suggests that periodic clamping of the Main Himalayan Thrust reduces the likelihood of earthquakes growing to larger magnitudes in accordance with hierarchical rupture models. The susceptibility of b-value to stress variations of roughly 0.1 points.kPa is consistent with recent estimates of b-value sensitivity to transient loading, although it remains high when compared to the stress-dependence associated with both static differential stress, and with long-term evolution during the seismic cycle. This discrepancy points to the large impact of stress transients on the dynamics of seismic rupture
Therapeutic Potential of Solanum torvum Sw. (Solanaceae) Leaf Extract against Salmonella Typhi in Wistar Rats
No full textInternational audienceAims: The present study find drugs based on plant extracts to alleviate the increase in mortality (10% in developing countries) and morbidity linked to typhoid fever, antityphoid and antioxidant activities of the hydroethanolic extract 95% of the leaves of Solanum torvum as well as the side effects were evaluated in vivo. Study Design: This study was a preclinical experimental investigation combining in vitro and in vivo approaches. Place and Duration of Study: the study were conducted in the laboratory of the University of Dschang and the animal house of the Department of Biochemistry, University of Dschang, Cameroon for 16 days treatment. Methodology: Antityphoid activity was assessed by the blood culture method in Wistar albino rates artificially infected with Salmonella Typhi ATCC 6539 and treated at doses 2.5; 5 and 10 mg/kg. In order to detect the side effects to which a patient who consumes this extract could be exposed, some tissues markers have been highlighted, as well as the hematological parameters and parameters linked to oxidative stress such as catalase, nitric oxide and malondialdehyde were evaluated in animals after treatment. Results: The study showed that administration of the extract at doses of 10, 5 and 2.5 mg/kg body weight has successfully cured infected animals after 7, 9 and 11 days of treatment respectively. The extracts dose-dependently normalized all hematological, biochemical and oxidative stress parameters that were predominantly altered by the infection. Among the doses tested, 10 mg/kg followed by the dose 5 mg/kg was the most effective in correcting side effects of the infection. While the dose 10 mg/kg exhibited some side effects, they were significantly milder compared to other doses, highlighting its relatively safer profile. Conclusion: the 95% hydroethanolic extract of the leaves of Solanum torvum could be a good candidate for the formulation of a traditionally improved drug in the management of patients suffering from typhoid fever
Combining transient dynamics and logistic‐asymptotic growth to study the recovery of two seabird populations after rat eradication
No full textInternational audienceUnderstanding demographic processes is crucial in ecology and conservation biology to assess how populations respond to environmental pressures. Although demographic parameters often react to disturbances, populations may remain in unstable age structures (transient dynamics) following such events. To explore the influence of transient dynamics in masked booby and red‐footed booby populations on Tromelin Island 15 years after rat eradication, we compared observed, transient, and asymptotic growth using count and capture–recapture (CR) data. CR data were used to estimate survival probability from Cormack–Jolly–Seber models and other vital rates such as breeding frequency and age at first breeding. We coupled asymptotic growth with a density‐dependent model for breeding site availability to project long‐term population growth. Both populations exhibited high adult survival (0.91–0.96) and breeding success (0.46–0.54). The masked booby juvenile survival was also high (0.86). Populations are expected to grow until breeding sites are saturated, in about a century. Comparison of asymptotic and transient growth suggests that population growth is linked to an intrinsic process and that both populations have undergone disruption in their age structure likely due to past predation by rats. Although the observed population growth appears to align more closely with transient growth, we could not entirely exclude the possibility that differences between asymptotic and observed growth rates may be due to data scarcity or age‐related variation in demographic parameters. Nevertheless, the study of transient dynamics allowed a better understanding of the differences observed between field counts and estimated asymptotic growth rates based on matrix population models
Influence of periodic checkerboard patterns on moisture content diffusion properties of wood material
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Intensité du blanchissement corallien 2025 à La Réunion et impacts du cyclone Garance
No full textInternational audienceLes récifs coralliens sont fortement menacés par les anomalies positives de températures durant la saison chaude, phénomène amplifié sous l’effet du changement climatique. Ces épisodes provoquent un blanchissement des colonies coralliennes, qui, s’il persiste au-delà de trois mois, entraîne la mort de ces colonies. À La Réunion, un suivi opérationnel a été initié en 2016 dans le cadre du programme BECOMING, reposant sur l’analyse des images Pléiades pour cartographier l’ampleur du phénomène. L’épisode de blanchissement de l’été 2025 a été étudié sur l’ensemble des récifs, du Cap La Houssaye à Grande Anse.Les images Pléiades, acquises via la plateforme DINAMIS, ont été analysées de manière diachronique. La calibration a reposé sur des relevés de terrain réalisés en palmes-masque-tuba sur 86 stations réparties entre platier et pente externe. Ces données in situ ont permis de valider et d’améliorer la chaîne de traitement développée depuis 2016.Les cartes obtenues permettent de révéler des zones fortement affectées par le blanchissement et d’autres relativement préservées. Les observations in situ permettent de préciser les genres coralliens les plus vulnérables et de quantifier le recouvrement corallien impacté. Un suivi complémentaire in situ, mené fin août/début septembre, a évalué la mortalité corallienne résultant de l’épisode. La spatialisation quantification de cette mortalité par imagerie satellitaire reste un défi car, contrairement à celle du blanchissement lui-même, la signature spectrale de cette mortalité est difficile à discriminer.Par ailleurs, suite au passage du cyclone Garance le 28 février 2025 à proximité de La Réunion, une analyse des panaches de dispersion des ravines a été conduite à partir d’images Sentinel, complétée par des mesures in situ. L’intégration de ces approches multi-capteurs constitue une avancée pour mieux comprendre les pressions à large échelle (cyclones, blanchissement corallien) combinées pesant sur les récifs coralliens réunionnais
Les enseignants de langues et les politiques éducatives européennes – Résultats d’une enquête internationale
No full textInternational audienceDie Europäische Union und der Europarat verfolgen eine Bildungspolitik, die die Entwicklung mehrsprachiger Kompetenzen fördert, wie sie als Ziele im GERS (Europarat, 2001) verankert sind. Die Aufnahme von Deskriptoren für diese Kompetenzen in den Begleitband zum GERS (Europarat, 2021) unterstreicht deren Bedeutung. Neben diesen wegweisenden Texten wurden in den letzten Jahren verschiedene offizielle Erklärungen (Europarat, 2022; Rat der Europäischen Union, 2019) veröffentlicht, die den Wert einer mehrsprachigen Bildung verdeutlichen.In Anlehnung an Studien über die Vorstellungen von Lehrenden zu Mehrsprachigkeit (z.B. Barras et al., 2019; Haukås, 2016) wurde im Rahmen des Projekts PEP (Promoting Plurilingual Education, ein von der EU kofinanziertes Erasmus+-Projekt) eine große internationale Umfrage durchgeführt mit einem Rücklauf von 800 vollständig ausgefüllten Fragebögen. In diesem Fragebogen war ein Abschnitt den Einstellungen von Sprachlehrenden zur mehrsprachigen Bildungspolitik in Europa gewidmet. Die Fragen wurden auf der Grundlage einer thematischen Inhaltsanalyse von Dokumenten entwickelt, die von der EU und dem Europarat im Zeitraum von 2008 bis 2023 veröffentlicht wurden, um Aussagen darüber zu identifizieren, was Mehrsprachigkeit ist und welche Vorteile sie bietet. Die Antworten der Lehrenden wurden mittels geschlossener Fragen in Form von MultipleChoice- und Reihungsfragen sowie offener Fragen zur weiterführenden Erläuterung erhoben. Die gesammelten Daten wurden einer statistischen und einer qualitativen Analyse unterzogen.In unserem Beitrag präsentieren wir die Ergebnisse dieser Analyse. Auf diese Weise wollen wir einerseits eine teilweise Übereinstimmung hinsichtlich der Anzahl der von den europäischen Bürger*innen zu erlernenden Sprachen und der Art dieser Sprachen (internationale Sprache, Sprache eines Nachbarlandes, “Adoptivsprache”, …) und andererseits die Motivation zur Zusammenarbeit mit den Lernenden im Bereich Mehrsprachigkeit aufzeigen, die sich für die Lehrenden aus den in den offiziellen Texten thematisierten Vorteilen ergibt.L’Union européenne et le Conseil de l’Europe déploient une politique éducative promouvant le développement des compétences plurilingues, ancrées comme objectifs dans le CECRL (Conseil de l’Europe, 2001). En intégrant des descripteurs pour ces compétences, le Volume complémentaire (Conseil de l’Europe, 2021) souligne leur importance. Au-delà de ces textes emblématiques, divers textes officiels (Conseil de l’Europe, 2022; Conseil de l’Union européenne, 2019) ont jalonné ces dernières années explicitant l’intérêt d’une éducation plurilingue.Dans la lignée des études sur les représentations des enseignants sur le plurilinguisme (p. e. Barras et al., 2019; Haukås, 2016), le projet PEP (Promouvoir l’éducation plurilingue, projet Erasmus+ co-financé par l’UE) a lancé une grande enquête internationale - qui a obtenu 800 réponses complètes. Dans ce questionnaire, une section a été dédiée aux opinions des enseignants de langues sur les politiques éducatives plurilingues européennes. Les questions ont été élaborées sur la base d’une analyse thématique de contenu des textes publiés par l’UE et le Conseil de l’Europe entre 2008 et 2023 permettant d’identifier les affirmations sur ce qu’est le plurilinguisme et les atouts de celui-ci. Les réponses des enseignants ont été recueillies à travers des questions fermées sous forme de QCM et d’items à sélectionner et des questions ouvertes permettant d’apporter des précisions. Les données collectées ont fait l’objet d’une analyse statistique et d’une analyse qualitative.Les résultats de cette analyse seront présentés afin de mettre en lumière, d’une part, des convergences partielles sur le nombre de langues à apprendre par les citoyens européens et et sur la nature de ces langues (langue internationale, langue d’un pays voisin, langue dite “adoptive”…) et, d’autre part, sur la force de motivation à travailler avec les apprenants sur le plurilinguisme que représentent pour les enseignants les atouts que les textes officiels évoquent de façon récurrente