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Possibilities, challenges, and limitations of dinosaur eggshells LA-ICP-MS U-Pb dating based on samples from Provence (Upper Cretaceous, France)
No full textObtaining accurate chronostratigraphic constraints on continental deposits is challenging, necessitating innovative dating approaches. Here, we investigate the feasibility of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) U-Pb dating of dinosaur eggshell fragments from the Late Cretaceous of Provence, France. Preliminary optical, Scanning Electron Microscopy (SEM), and cathodoluminescence (CL) analyses were critical for identifying zones of optimal preservation and mitigating potential diagenetic contamination. Results from two samples attributed to Megaloolithus mamillare and Cairanoolithus dughii yielded ages of 68.1 ± 4.7 Ma and 68.7 ± 10.2 Ma, respectively, broadly consistent with regional stratigraphic markers. Element mapping reveals significant spatial variation in U and Pb concentrations within individual eggshells, with zones of high contamination contrasting with well-preserved cores. The data highlight the crucial role of diagenesis and organic matter in influencing U-Pb system behavior, although it appears to be limited to early diagenesis. While LA-ICP-MS U-Pb dating of dinosaur eggshells presents substantial challenges, this study demonstrates its potential with careful sample selection and nuanced interpretation, paving the way for further refinement and broader application
Plant-wax n-alkanes from the central Congo Basin as palaeo-environmental and -climatic proxies
No full textInternational audienceThe central Congo Basin is home to the world's largest tropical peatland complex and is covered with swamp forest. In the face of climate change and future human activities in the region, it is important to understand the factors that determine the nature and dynamics of the peatland vegetation cover. One way to gain insight into these factors is to reconstruct the history of the central Congo Basin peatlands. Analysing lipid biomarkers extracted from peat cores such as plant wax n-alkanes enables past environmental and climatic conditions to be reconstructed. However, there is currently no information on how the production of plant waxes by different plant species influences the abundance and isotopic composition of n-alkanes in peat and other archives in the Congo Basin. In this study we analysed plant wax n-alkane abundances, delta C-13 and delta D values according to photosynthetic pathways (C-3 vs. C-4), angiosperm subclasses (dicotyledons vs. monocotyledons), and source water delta D values in the dominant plant types (trees, shrubs, and herbs) in the peatland area of the Cuvette Department in the Republic of the Congo. Our dataset enables the definition of a new n-alkane distribution index, named GRIND, that distinguishes between C-3 (mostly dicotyledons) and C-4 (monocotyledons) plants as follows: (n-C-27 + n-C-33 + n-C-35)/(n-C-25 + n-C-27 + n-C-29 + n-C-31 + n-C-33 + n-C-35). This index may therefore be used to analyse Central African peat deposits and derive the relative abundance of C-3 and C-4 plant waxes in the past, independently of delta C-13 measurements. Furthermore, delta C-13 values from the central Congo Basin and other African sites suggest that environments with high relative humidity (> 80%) are characterised by very negative delta C-13 values (i.e., < -37 parts per thousand) of n-C-29 and n-C-31 alkanes. This observation highlights the potential of n-alkane delta C-13 in deriving climatic information under high relative humidity conditions in Central African lowlands, and contribute to palaeo-climatic reconstructions. Finally, the delta D values of n-C-29 and n-C-31 alkanes demonstrate that, despite contrasting apparent fractionation values associated with photosynthetic pathways and plant functional types - which can be accounted for using delta C-13 and pollen data in sedimentary deposits - they reliably reflect the delta D of environmental water. This confirms that plant wax n-alkane delta D values are effective tools for reconstructing palaeo-climatic changes in equatorial regions
Atomic Spectroscopy Probes of New Physics
No full textInternational audiencePrecision spectroscopy has long played a central role in testing the foundations of physics, from the early insights that led to the development of quantum mechanics to the validation of quantum electrodynamics and the determination of fundamental constants. Today, advances in atomic and molecular spectroscopy enable sensitive searches for physics beyond the Standard Model. A broad class of well-motivated extensions predicts new light degrees of freedom with feeble couplings to electrons, muons, and nucleons, giving rise to tiny spin-independent interactions that can be probed at low energies. In this review, we present a unified overview of spectroscopic searches for such interactions. We discuss the effective theoretical framework connecting fundamental interactions to atomic and nuclear observables, survey the key experimental and theoretical strategies, and review the atomic and molecular systems providing the strongest sensitivity. We conclude with updated spectroscopic constraints on representative benchmark models, highlighting the unique and complementary role of precision spectroscopy in exploring new fundamental interactions
Emil Orlik – Un artiste sécessionniste pragois: Les réseaux centre-européens d'Europe du japonisme dans le modernisme berlinois
No full textInternational audienceDas Leben und die Karriere von Emil Orlik sind ein Symbol für die Lebendigkeit des kulturellen Austauschs im deutschsprachigen Raum vor und nach dem Ersten Weltkrieg. Der 1870 in Prag geborene Orlik war ein echter Vertreter des Habsburgerreiches mit einer entsprechend komplexen Identität – jüdisch, tschechisch und deutschsprachig –, die ihn in die Nähe der böhmischen Deutschen rückte. Um die Jahrhundertwende war er als Mitglied der Wiener Secession fester Bestandteil der Kunst- und Kulturszene der Doppelmonarchie, und der ebenfalls aus Prag stammende Rainer Maria Rilke veröffentlichte 1900 seinen Orlik gewidmeten Artikel „Ein Prager Künstler“ in der Secessionszeitschrift Ver Sacrum. Wegen seiner ausgedehnten Reisendurch Europa und seines fast einjährigen Aufenthalts in Japan, während dessen er zum begeisterten Japonisten wurde, konnte Orlik viel Erfahrung in die Prager und Wiener Kunstszene einbringen. Nachdem Orlik 1905 mit der Gruppe um Gustav Klimt aus der Wiener Secession ausgetreten war, richtete er sein Atelier in Berlin ein. Er wurde zum Professor an der Unterrichtsanstalt des Berliner Kunstgewerbemuseums ernannt, eine Position, die er bis zu seiner Pensionierung innehatte. In Berlin blühte Orlik als Illustrator auf – bahnbrechend wurden seine Illustrationen für die deutsche Ausgabe der Werke von Lafcadio Hearn, die von der in Brody geborenen Berta Franzos übersetzt wurden –, aber er arbeitete auch als Fotograf sowie als Bühnenbildner und Kostümdesigner, wobei er in letzterem Bereich jahrelang mit Max Reinhardt zusammenarbeitete. In Berlin war er bald so gut integriert, dass er als „deutscher Künstler“ galt.Orlik verkehrte mit Mitgliedern der Berliner Secession wie Max Slevogt, Lovis Corinth, Max Kruse und Max Liebermann. Er starb 1932 in der deutschen Hauptstadt, wurde aber in seinem geliebten Prag beigesetzt.The life and career of Emil Orlik symbolize the vibrancy of cultural exchange in the German-speaking world before and after the First World War. Born in Prague in 1870, Orlik was a true representative of the Habsburg Empire, with a correspondingly complex identity—Jewish, Czech, and German-speaking—which placed him close to the community of Bohemian Germans. Around the turn of the century, he became an integral part of the art and cultural scene of the Dual Monarchy as a member of the Vienna Secession, and the fellow Prague-born writer Rainer Maria Rilke published in 1900 his article “A Prague Artist,” dedicated to Orlik, in the Secession journal Ver Sacrum.Because of his extensive travels across Europe and his nearly year-long stay in Japan—during which he became an enthusiastic Japonist—Orlik brought a wealth of experience to the Prague and Viennese art worlds. After leaving the Vienna Secession in 1905 together with the group around Gustav Klimt, he established his studio in Berlin. There, he was appointed professor at the School of the Museum of Decorative Arts, a position he held until his retirement.In Berlin, Orlik flourished as an illustrator—his illustrations for the German edition of the works of Lafcadio Hearn, translated by Berta Franzos, who was born in Brody, became groundbreaking—but he also worked as a photographer as well as a stage and costume designer, collaborating for many years in the latter role with Max Reinhardt. In Berlin, he soon became so well integrated that he was regarded as a “German artist.”Orlik associated with members of the Berlin Secession such as Max Slevogt, Lovis Corinth, Max Kruse, and Max Liebermann. He died in 1932 in the German capital but was buried in his beloved Prague.La vie et la carrière d’Emil Orlik symbolisent la vitalité des échanges culturels dans le monde germanophone avant et après la Première Guerre mondiale. Né à Prague en 1870, Orlik est un pur produit de l’Empire des Habsbourg, avec une identité complexe – juive, tchèque et germanophone – qui le rapproche de la communauté des Allemands de Bohême. Au tournant du siècle, il devient membre à part entière de la scène artistique et culturelle de la Double Monarchie comme membre de la Sécession viennoise, et l’écrivain Rainer Maria Rilke, lui aussi originaire de Prague, publie en 1900 dans la revue de la Sécession, Ver Sacrum, un article qui lui est consacré, intitulé « Un artiste pragois ».En raison de ses nombreux voyages à travers l’Europe et de son séjour de près d’un an au Japon – au cours duquel il devient un japoniste enthousiaste –, Orlik apporte une riche contribution aux milieux artistiques pragois et viennois. Après avoir quitté la Sécession viennoise en 1905, en même temps que le groupe gravitant autour de Gustav Klimt, il installe son atelier à Berlin. Là, il est nommé professeur à l’École du Musée des arts décoratifs, poste qu’il occupe jusqu’à sa retraite.À Berlin, Orlik s’épanouit comme illustrateur – ses illustrations pour l’édition allemande des œuvres de Lafcadio Hearn, traduites par Berta Franzos, née à Brody, font date – mais il travaille aussi comme photographe ainsi que comme scénographe et costumier, collaborant pendant de nombreuses années, dans ce dernier domaine, avec Max Reinhardt. À Berlin, il s’intègre si bien qu’il est bientôt considéré comme un « artiste allemand ».Orlik fréquente des membres de la Sécession berlinoise tels que Max Slevogt, Lovis Corinth, Max Kruse et Max Liebermann. Il meurt en 1932 dans la capitale allemande, mais est inhumé dans sa Prague bien-aimée
Chimie du solide et de l’énergie: [résumé des cours et travaux : 2021-2022]
No full textInternational audienc
GWTC-4.0: Population Properties of Merging Compact Binaries
No full textInternational audienceWe detail the population properties of merging compact objects using 158 mergers from the cumulative Gravitational-Wave Transient Catalog 4.0, which includes three types of binary mergers: binary neutron star, neutron star--black hole binary, and binary black hole mergers. We resolve multiple over- and under-densities in the black hole mass distribution: features persist at primary masses of and with a possible third feature at . These are departures from an otherwise power-law-like continuum that steepens above . Binary black holes with primary masses near are more likely to have less massive secondaries, with a mass ratio distribution peaking at , potentially a signature of stable mass transfer during binary evolution. Black hole spins are inferred to be non-extremal, with 90% of black holes having , and preferentially aligned with binary orbits, implying many merging binaries form in isolation. However, we find a significant fraction, 0.24-0.42, of binaries have negative effective inspiral spins, suggesting many could be formed dynamically in gas-free environments. We find evidence for correlation between effective inspiral spin and mass ratio, though it is unclear if this is driven by variation in the mode of the distribution or the width. (Abridged
Resource landscape shapes the composition and stability of the human vaginal microbiota
No full textInternational audienceThe vaginal microbiota is associated with the health of women and newborns alike. Despite its comparatively simple composition relative to other human microbiota systems, the mechanisms underpinning the dynamics and stability of vaginal microbial communities remain elusive. A crucial, yet so far underexplored, aspect of vaginal microbiota ecology is the role played by nutritional resources. Glycogen and its derivatives, produced by vaginal epithelia, are accessible to all bacterial constituents of the microbiota. Concurrently, free sialic acid and fucose offer supplementary nutritional resources to bacterial strains capable of cleaving them from glycans, which are structurally integral to mucus. Notably, bacteria adept at sialic acid exploitation are often correlated with adverse clinical outcomes and are frequently implicated in bacterial vaginosis (BV). In this study, we introduce a novel mathematical model tailored to human vaginal microbiota dynamics to explore the interactions between bacteria and their respective nutritional landscape. Our resource-based model examines the impact of the relative availability of glycogen derivatives (accessible to all bacterial species) and sialic acid (exclusive to some BV-associated bacteria) on the composition of the vaginal microbiota. Our findings elucidate that the success of BV-associated bacteria is intricately linked to their exclusive access to specific nutritional resources. This private access fortifies communities dominated by BV-associated bacteria, rendering them resilient to compositional transitions. We empirically corroborate our model prediction with longitudinal clinical data on microbiota composition and previously unpublished metabolomic profiles obtained from a North American cohort. The insights gleaned from this study shed light on potential pathways for BV prevention and treatment
All-sky search for long-duration gravitational-wave transients in the first part of the fourth LIGO-Virgo-KAGRA Observing run
No full textInternational audienceWe present an all-sky search for long-duration gravitational waves (GWs) from the first part of the LIGO-Virgo-KAGRA fourth observing run (O4), called O4a and comprising data taken between 24 May 2023 and 16 January 2024. The GW signals targeted by this search are the so-called "long-duration" (> 1 s) transients expected from a variety of astrophysical processes, including non-axisymmetric deformations in magnetars or eccentric binary coalescences. We make minimal assumptions on the emitted GW waveforms in terms of morphologies and durations. Overall, our search targets signals with durations ~1-1000 s and frequency content in the range 16-2048 Hz. In the absence of significant detections, we report the sensitivity limits of our search in terms of root-sum-square signal amplitude (hrss) of reference waveforms. These limits improve upon the results from the third LIGO-Virgo-KAGRA observing run (O3) by about 30% on average. Moreover, this analysis demonstrates substantial progress in our ability to search for long-duration GW signals owing to enhancements in pipeline detection efficiencies. As detector sensitivities continue to advance and observational runs grow longer, unmodeled long-duration searches will increasingly be able to explore a range of compelling astrophysical scenarios involving neutron stars and black holes