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Tailoring nanometric vanadium dioxide morphology to tune thermochromic optical properties
No full textInternational audienc
Photobleaching Effects Caused by Ambient Light on the Radiation‐Induced Attenuation of Germanosilicate Optical Fibers
No full textInternational audienceWe demonstrate the influence of the ambient lightning on the X‐ray radiation‐induced attenuation (RIA) in the visible to infrared domains of germanosilicate optical fibers (OFs). RIA spectra and kinetics are then discussed depending on the illumination conditions in terms of point defects and also from a practical point of view. In the presence of an external illumination, the RIA levels can change and therefore lead to misinterpretations during irradiation campaigns. This study highlights the role of the GeY defect in infrared Ge‐doped OF RIA and its significant sensitivity to photobleaching
Insights into the cognitive evolution of genus Homo: Eye-tracking analysis of stone tool recognition in trained versus novice modern humans
No full textInternational audienceEye tracking technologies have recently been used to analyze the visual exploration of stone tool stimuli by modern humans to investigate the cognition of our ancestors. As a tooling species, modern humans show remarkable abilities when it comes to understanding and manipulating complex tools, such as a microscope. Nevertheless, our earliest technological steps, at least the first ones for which we have archaeological evidence, were stone tools, which today might appear easier to grasp than a highly sophisticated surgical telemanipulator. However, the complexity and diversity of lithic industries require a certain level of knowledge to be fully understood. Thus, the question remains whether modern humans can truly extract relevant features from stone tools to distinguish them, for example, from stones fractured by uncontrolled percussion (broken stones), which might look like the first lithic industries. Naive participants, divided into two groups with one receiving a training about stone tool features and the other not, were asked to distinguish stone tools from broken stones. Results show that participants needed a minimal level of knowledge to distinguish choppers or handaxes from broken stones. Nevertheless, trained participants were still not able to correctly classify unknown types of stone tools as tools, suggesting that they needed deeper knowledge to transfer their skills. Our findings underline the important role of technical knowledge in our ancestors’ expertise in stone knapping
High-Resolution Facies Characterization and Metre-Scale Depositional Organization of Palustrine-Lacustrine Carbonates
No full textAccurate 3D modelling of continental limestone reservoirs is still hindered by the high spatial variability of their flow properties. This variability results from the combination of heterogeneous and laterally discontinuous sedimentary facies with vertically stacked pedogenic overprints, which remain poorly constrained at the multi-meter scale. To address this issue, this study provides a sedimentological and stratigraphic characterization of the Aquitanian Pithiviers Limestones hosting the vadose zone of the Beauce aquifer (central France). This analysis takes advantage of a high-resolution dataset (eight 25-m-deep cored boreholes, spaced 5 to 8 m apart). Eleven facies were identified grouped into lacustrine, lake-margins and palustrine depositional environments. Two cross-sections (22 m long) reveal a heterogeneous architecture structured by three hierarchical orders of cyclicity: (1) medium-term cycles (several metres thick) record alternations between widespread lacustrine and palustrine conditions, (2) short-term cycles that document vertical and lateral facies shifts at the metre scale and (3) very-short-term cycles illustrating sub-metre to metre-scale facies variability driven by autogenic processes. Palaeogeographical reconstructions highlight three depositional organizations: lacustrine-dominated, palustrine-dominated, and mixed configurations. Mixed configurations exhibit pronounced spatial heterogeneity, with lacustrine, lake-margins, and palustrine facies coexisting laterally at the scale of the study site, over distances of a few metres. Lake-margins deposits are restricted in extent and frequently absent from vertical successions, indicating rapid pedogenic overprinting. These results demonstrate that autogenic processes dominate metre-scale facies architecture in lacustrine–palustrine carbonate systems and must be explicitly accounted for when modelling fluid flow and connectivity in continental carbonate aquifers
Modélisation des spatialités historiques en réseaux : l’exemple du fait religieux au Moyen-Age
No full textInternational audienceSi le potentiel heuristique des « géovisualisations » proposant des explorations des données a été beaucoup démontré, leur caractère démonstratif dépend cependant de la complexité des données et des fonctionnalités d’exploration mises en oeuvre. Cela conduit à développer des environnements ad-hoc d’exploration visuelle des données articulant conceptualisation théorique et observation empirique (Andrienko &al., Grandjean M.). Ces développements nécessitent en amont des formalisations des données qui constituent elles-mêmes des étapes de mise en ordre, de modélisation et donc de compréhension du phénomène à un niveau méta.Dans la modélisation que nous proposons, les entités spatiales sont des établissements religieux (monastères ou collégiales) en France au moyen-âge. Les questions qui leurs sont associées, à savoir comprendre les logiques d’implantation, d’évolution institutionnelle, et d’imbrication des réseaux relèvent à la fois d’analyses longitudinales et de l’analyse spatiale et spatio-temporelle, intégrant une approche territoriale et une approche en réseau évoluant au cours du temps.Pour approcher ces questions nous avons conçu un environnement de géovisualisation où interagissent distributions géographiques et statistiques dans le temps. Le phénomène peut être exploré selon trois entrées : l’évolution des organisations, les événements et le changement, et la structuration des réseaux et leur organisation spatiale.Nous revenons sur les données et le processus de conception interdisciplinaire1 qui a conduit à élaborer un modèle de données adapté, simplifié. Nous présentons ensuite l’environnement développé, FactoViz, et ses fonctionnalités, en illustrant la capacité démonstrative de certaines visualisations pour la connaissance de la structuration spatiale du phénomène
FANTASTIC CLINOFORMS AND WHERE TO FIND THEM? A DETAILED LOOK AT FLUVIAL TO DELTAIC DEPOSITS IN GALE'S LAYERED
No full textInternational audienceCuriosity continues to explore the layered sulfate unit (LSu) of Gale crater as it ascends Mount Sharp. In mid-2025, the rover arrived in the orbitally-defined “boxwork” unit (Fig. 1). There, diagenetically-altered, fine-grained textures have been identified hinting at a probable lacustrine setting [1-2].By contrast, the walls of this valley, and particularly that of the Mishe Mokwa, Cordillera, and western Texoli buttes (Fig. 1), display a wealth of multi-scale sedimentary structures. Some of them indicate that complex wet-aeolian alternations occurred at the time of the deposition [3] as a continuation of the previously studied Mirador fm. (e.g., [4-5]). Yet, these outcrops have also revealed unprecedented clinoform geometries.Using image data acquired with ChemCam’s RMI, we detail three types of clinoform strata within the buttes surrounding this area (Fig. 1). These clinoforms differ in size and process from those recognized earlier in the mission at e.g., Kimberley [6]. Among them, we notably propose the first in-situ observation of deltaic geometries by Curiosity
Estimating patient-to-patient bacterial transmission likelihood based on antimicrobial resistance profile similarity and rarity
No full textHealthcare-associated bacterial outbreaks are difficult to detect with routine phenotypic data, and incidence-based alerts generate false alarms. We present a method to estimate how close two patient isolates are in a transmission chain using antimicrobial resistance profiles. The pairwise transmission proximity (PTR) score combines two ideas: isolates are considered closer when their resistance profiles are more similar, and when that shared profile is uncommon in the sampled population. Practically, this is implemented by counting how many other isolates fall within the same phenotypic distance of each isolate and using these counts to rank pairs; the score is used as a relative proximity measure rather than a calibrated probability. Phenotypic distance is computed from minimum inhibitory concentrations (MICs) as the average absolute difference across drugs, or from binary susceptible/resistant profiles as an equivalent scaled mismatch count. We simulate pathogen divergence, resistance evolution, and patient-to-patient transmissions on evolutionary trees while varying transmission and mutation rates and the number of resistance traits. In closed-population simulations with complete sampling, the PTR ranking tracks time since common ancestry and provides useful discrimination for identifying inter-patient transmission events and for distinguishing inter-from intra-patient pairs, with better performance at moderate rates and larger resistance panels. The method is intended as a high-coverage screening signal to prioritize epidemiologic review or confirmatory genomics; calibration and clinical utility require external validation
Séries génératrices de matroïde
No full textGiven a finite set - for instance, the set of edges in a finite multigraph - it is customary to study the poset of its subsets and, in particular, its incidence algebra, which forms a subalgebra of the algebra of upper triangular matrices. As a vector space, this algebra is spanned by pairs of subsets satisfying . Notably, there is a bijection between these pairs and the minors of a matroid (or graph) defined on ; here, the elements (edges) in are interpreted as being deleted, while those in are contracted, so that the support of the resulting minor is given by .This is why our incidence algebra is highly useful in matroid theory: it can be employed just like formal power series, notably by supporting operations such as differentiation and substitution. This approach is closely linked to the axiomatic characterizations of matroids and to a careful study of the greedy algorithm. Consequently, it should enable us to tackle, at the very least, every exact enumeration problem related to matroids and oriented matroids (including Tutte polynomials). To illustrate this idea, we provide concise formulations and proofs for many classical and new results in the theories of graphs, matroids, and oriented matroids, emphasizing the benefits of studying a matroid together with its minors as a single object - what we call a matroid power series
Entre Néron et les Flaviens : les pestilences à Rome et dans l'empire
No full textInternational audienc
Did lunar tides sustain the early Earth’s dynamo?
No full textInternational audienceGeological data show that, early in its history, the Earth had a large-scale magnetic field with an amplitude comparable to the one of the present geomagnetic field. However, its origin remains enigmatic and various mechanisms have been proposed to explain the Earth’s field over geological time scales. Here, we critically evaluate whether tidal forcing could explain the ancient geodynamo, by combining constraints from geophysical models of the Earth–Moon system and predictions from turbulence studies. Our analysis shows that lunar tidal forcing could have been sufficiently strong before - 3.25 Gy to trigger turbulence within the Earth’s core, and potentially to sustain dynamo action during that interval. Then, we propose new scaling laws for the magnetic field amplitude B . We expect the latter to scale as B ∝ β 4 / 3 , where β is the equatorial ellipticity of the liquid core, if the turbulence involves weak interactions of three-dimensional inertial waves. Alternatively, in the regime of strong tidal forcing, the expected scaling becomes B ∝ β . When extrapolated to the Earth’s core, it suggests that tidal forcing alone was too weak to possibly explain the ancient geomagnetic field. Therefore, our study indirectly favours another origin for the early Earth’s dynamo on long time scales (e.g. exsolution of light elements atop the core, or thermal convection due to secular cooling)