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Commentary on Seersholm Et al.: Yersinia pestis Infection Is Not Synonymous With Deadly Plague in Neolithic Scandinavia
No full textInternational audienceABSTRACT Objectives Emerging genomic evidence has identified ancestral strains of Yersinia pestis in ancient human populations, which has sparked debates about its pathogenic role in later Neolithic societies. Here, we review published evidence linking anthropological and biological data reflecting the past natural history of Y. pestis infection. Materials and Methods Review of reported ancient Y. pestis genomes, paleomicrobiological, archaeological, and ecological data related to ancient plague. Results and Discussion While some researchers attributed the Scandinavian Neolithic population decline to plague epidemics, we argue that early Y. pestis strains were more likely associated with outbreaks of food‐borne enteritis rather than flea‐borne plague. This hypothesis is supported by genetic, archaeological, and ecological analyses, which indicate that Y. pestis evolved key flea‐borne transmission mechanisms only later in its history
Role of behaviour change in controlling the 2022 Paris mpox outbreak
No full textInternational audienceThe 2022 mpox outbreak led to a rapid case surge among men-who-have-sex-with-men (MSM) in previously unaffected regions, followed by a sudden decline, whose drivers remain unclear. We developed a network model of mpox transmission among MSM based on sexual behaviour data, focusing on the Paris region epidemic. Our analysis tested three drivers for the decline: postexposure prophylaxis (PEP) vaccination; immunity among highly active MSM; and behavioural adaptations, either uniform in the population or based on individual risk factors. Behavioural changes adopted by 49% (95% CI 47-51%) of MSM, regardless of risk factors, best explained the decline, preventing an estimated 68% (15-99%) of potential cases in summer 2022. To validate model predictions, we analyzed data from the 2023 ERAS survey and found that 46% (45-48%) of MSM in the region reported reducing their number of sexual partners during that period-closely matching model estimates. In contrast, PEP vaccination and immunity among highly active MSM were insufficient to halt the outbreak. Both model predictions and survey results underscore the role of widespread, spontaneous behavioural adaptations, regardless of risk profile, in driving the epidemic downturn. These findings highlight the importance of effective risk communication and community engagement in outbreak managemen
A High Geometric Albedo for LTT9779b Points Towards a Metal-rich Atmosphere and Silicate Clouds
No full textInternational audienceAims: In this work, we aim to confirm the high albedo of the benchmark ultrahot Neptune LTT9779b using 20 secondary eclipse measurements of the planet observed with CHEOPS. In addition, we perform a search for variability in the reflected light intensity of the planet as a function of time. Methods: First, we used the TESS follow-up data of LTT9779b from three sectors (2, 29, and 69) to remodel the transit signature and estimate an updated set of transit and ephemeris parameters, which were directly used in the modeling of the secondary eclipse lightcurves. This involved a critical noise-treatment algorithm, including sophisticated techniques such as wavelet denoising and Gaussian Process (GP) regression, to constrain noise levels from various sources. In addition to using the officially released reduced aperture photometry data from CHEOPS DRP, we also reduced the raw data using an independent PSF photometry pipeline, known as PIPE, to verify the robustness of our analysis. The extracted secondary eclipse lightcurves were modeled using the PYCHEOPS package, where we have detrended the background noise correlated with the spacecraft roll angle, originating from the inhomogeneous and asymmetric shape of the CHEOPS point spread function, using an N-order glint function. Results: Our independent lightcurve analyses have resulted in consistent estimations of the eclipse depths, with values of 89.913.7 ppm for the DRP analysis and 85.213.1 ppm from PIPE, indicating a high degree of statistical agreement. Adopting the DRP value yields a highly constrained geometric albedo of 0.730.11. No significant eclipse depth variability is detected down to a level of 37 ppm. Conclusions: Our results confirm that LTT9779b exhibits a strikingly high optical albedo, which substantially reduces the internal energy budget of the planet compared to more opaque..
A short introduction to boundary symmetries
No full textInternational audienceSupport material for lectures at the Mai '25 Galileo Galilei Institute school on asymptotic symmetries and flat holography. Contains an introduction to Noether theorem for gauge theories and gravity, covariant phase space formalism, boundary and asymptotic symmetries, future null infinity in Bondi-Sachs coordinates and in Penrose conformal compactification, BMS symmetries and their charges and fluxes. Includes an original and pedagogical derivation of the BMS group using only Minkowski, and an original derivation of an integral Hamiltonian generator for a scalar field on a null hypersurface
From modelling to management: improving decision-making through contextualized marine radiological impact assessments after a nuclear accident
No full textInternational audienceAdapted management of accidental release of radionuclide to the sea relies especially on the application of radiological impact assessment models. While recent site-specific marine transport models provide detailed simulations, their outputs are often presented without considering maritime boundaries, that imply in practice different legal frameworks and may therefore lead to different management strategies within a physically continuous area. This study addressed that gap by integrating maritime boundaries in a radiological impact assessment of a hypothetical accidental liquid release of 137Cs at the Flamanville NPP in the English Channel.The assessment combined the STERNE marine dispersion model, which integrates biokinetic equations, and dosimetric calculations based on the ERICA Tool. Impact characterization focuses on the contamination of non- human biota, for their own protection, and relates to benchmarks for radiation protection. Potential seafood activities are assessed against regulatory limits for commercialization after a nuclear accident. One-year dispersion simulations were carried out for a one-week Fukushima-type release, accounting for seasonal fluc-tuations in hydrodynamics.Spatial dispersion showed an extensive plume crossing territorial seas, notably contaminating the territorial sea of Jersey and Guernsey, two British Crown Dependencies. The plume arrived earlier at Jersey where higher activities are estimated. Calculated activities and dose rates within those territorial seas remained mainly below radiation protection benchmarks.To improve communication and decision-making, a novel indicator was introduced for the impact charac-terization: the number of days during which benchmarks values are exceeded at each grid cell. These exceedance maps offer a time-based, easily interpretable and transparent output that could enhance risk communication. It provides an adapted tool when considering regulatory uncertainties. For instance, the time perspective could make it easier to forecast economic loss and ensure for the public a better understanding of authority decisions, restoring consumer confidence in marine seafood and enabling economic activity to recover more quickly. In this study, Flamanville vicinity showed up to 70 exceedance days when considering seafood marketing limits, while values were much lower in the other parts of the Channel
Co-option of an ancestral peptidase controls developmental patterning in multicellular cyanobacteria
No full textInternational audienceSpatial patterning in multicellular organisms is commonly explained by Turing-type reaction-diffusion systems, but the maturation of diffusible inhibitors remains poorly understood. In the cyanobacterium Nostoc PCC 7120, nitrogen deprivation triggers a pattern of nitrogen-fixing heterocysts regulated by HetR and inhibitory peptides, including PatX. We uncover the post-translational mechanism controlling PatX maturation, demonstrating its export and subsequent processing by the peptidase PatP. We identify HRGTGR, a PatX-derived hexapeptide, as the direct inhibitor of HetR, linking maturation to suppressed differentiation. Genomic analyses reveal that patP is ancient and conserved across all cyanobacteria, predating the patX-hetR module found only in filamentous clades. We therefore propose that this ancient peptidase was coopted to process a new ligand, transforming a proteolytic event into a spatial patterning mechanism. This repurposing parallels eukaryotic signaling, underscoring a universal principle in the emergence of multicellular organization and providing a model for how complex patterns evolve from ''simple'' components.</div
Habilitation à diriger des recherche - La génération d’impulsions pour les communications radiofréquences : des spécifications aux circuits-intégrés
No full textThis document for the French Habilitation to Supervise Research is a book dealing with the generation of pulses for radio-frequency communications, particularly short range between 3.1 GHz and 10.6 GHz.Ce document de candidature à l’Habilitation à Diriger des Recherches est un ouvrage traitant de la génération d’impulsions pour les communications radio-fréquences, notamment courte portée entre 3,1 GHz et 10,6 GHz
Probing General Relativity on Cosmological Scales in the 2040s
No full textInternational audienceGeneral relativity is exquisitely tested in strong-field regimes, yet its validity on cosmological scales remains largely unexplored. Upcoming wide and deep large-scale structure surveys will access the ultra-large, linear scales where relativistic effects - Doppler terms, gravitational redshift, lensing magnification, and potential evolution - leave significant imprints in the clustering of galaxies. These signatures represent unique probes of spacetime that are inaccessible to standard Newtonian analyses but increasingly important as survey volumes grow. We outline the scientific potential of next-generation facilities, such as those envisioned within ESO's Expanding Horizons programme, to deliver the first robust measurements of relativistic effects in large-scale structure through multi-tracer power spectra and the single-tracer bispectrum of high-redshift Lyman-break galaxies. Detecting these contributions would open a new window on gravity, enabling precision tests of general relativity and its alternatives on cosmological scales in the 2040s
"Not retrograde, but still capable of great improvement”: exploring Alpine modernisation through the life of an Italian Travelling Chair for Agriculture (1869-1929)
No full textInternational audienceThis talk explores the role of a Travelling Chair for Agriculture (it. Cattedra Ambulante di Agricoltura) in the Italian Western Alps. This agrarian institution was part of a larger attempt to modernizing agricultural practices all over Italy through scientific experimentation and dissemination since the second half of 19th century. Using archival research, the lecture examines how expert knowledge about Alpine farming was produced within a complex socio-technical interplay between formal science and local, informal forms of knowledge. Aligning with recent perspectives in critical development studies, it inquires into the emotional and idealistic dimensions of development interventions, showing that agricultural experts were driven by a genuine desire to improve local livelihoods rather than governmentalizing motives. These findings invite us to reframe current narratives about modernization processes as an inevitable erasure of local cultures and offer a nuanced, decentered perspective on Alpine agricultural modernization as a multifaceted movement shaped by historical and political dynamics
Precise temporal localisation of M/EEG effects with Bayesian generalised additive multilevel models
No full textAbstract Time-resolved electrophysiological measurements such as those obtained through magneto- and electroencephalography (M/EEG) offer a unique window onto the neural activity underlying cognitive processes. Researchers are often interested in determining whether and when these signals differ across experimental conditions or participant groups. The conventional approach involves mass univariate statistical testing across time and space followed by corrections for multiple comparisons or some form of cluster-based inference. While effective for controlling error rates at the cluster-level, clusterbased inference comes with a significant limitation: by shifting the focus of inference from individual time points to clusters, it prevents drawing conclusions about the precise onset or offset of observed effects. Here, we present a model-based alternative for analysing M/EEG timeseries, such as event-related potentials or time-resolved decoding accuracy. Our approach leverages Bayesian generalised additive multilevel models, providing posterior odds that an effect exceeds zero (or chance) at each time point, while naturally accounting for temporal dependencies and between-subject variability. Using both simulated and empirical M/EEG datasets, we show that this approach substantially outperforms conventional methods in estimating the onset and offset of neural effects, yielding more precise and reliable estimates. We provide an open-source R package implementing the method and describe how it can be integrated into M/EEG analysis pipelines using MNE-Python