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Photocatalysis in volume using anatase-TiO2-SiO2 monoliths for efficient VOC photodegradation
No full textInternational audienceSelf-standing anatase-TiO₂-SiO₂ ceramics with a multiscale porous architecture demonstrated improved performance in the photodegradation of volatile organic compounds, achieving 80% propan-2-one mineralisation for Ti/Si molar ratio as low as 0.08-0.15...
Joining the Dots: A Techno-visual Approach to the Earliest Painted Portable Art in Tierra del Fuego and its Implications for the Identification of a Deep-time Artistic Tradition
No full textInternational audienceThis paper presents the first techno-visual analyses of the earliest painted portable art from Southern Tierra del Fuego (Southern South America). The artefact is a maritime mammal bone splinter painted with five red dots in a row; it was found in site Tunel I, in a layer dated ca. 6500-6700 cal. BP. The deep significance of this finding is related to the following facts: a) it is the earliest and southernmost evidence of decorative painting created by Indigenous societies in the world; b) it provides a deep-time date for the onset of avisual culture found in other art forms developed in the region (body painting and wooden artefactpainted decorations created by the Yagan society in historical times; painted rock art) all of which included motifs made with rows of dots. Differences with deep-time engraved portable art on bone artefacts are also presented, and related to the disparate techno-visual affordances offered by painting vs engraving techniques. Results from microscopic observations, geometric morphometrics and archaeometric analyses –XRF, SEM-EDS, μ-Raman, μ-EDXRF imaging and 3D-CM– shed light on the technical choices and practices underlying the production of this painted artefact and contribute to the knowledge construction of a deep-time Fuegian artistic tradition
Deciphering the complex ecology of plant and mycoviruses in wild grasses by analysing the virome associated with individual plants
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Deciphering the complex ecology of plant and mycoviruses in wild grasses by analysing the virome associated with individual plants
No full textInternational audienceBefore the domestication of plants, plant viruses were co-evolving with wild plants growing in mixed species communities, thereby potentially resulting in complex interactions (antagonism, commensalism, mutualism). The development of agriculture deeply modified ecosystems, altering the dynamics of virus-plant pathosystems and accelerating the rate of virus evolution and emergence. High-throughput sequencing technologies have now enabled more comprehensive studies of viromes at different scales, from individual plants to entire ecosystems, offering insights into virus ecology within agro-ecological landscapes. Recent virome studies revealed diversified and largely unknown viral communities in natural ecosystems, with high rates of co-infection and a high abundance of persistent or cryptic viruses. However, many studies focused on plant pools, showing the viral richness but missing important ecological information such as viral prevalence, co-infection and spatial distribution of virus infection. In this context, we conducted a study in the Natural Park “Burdinale-Mehaigne” (Belgium) to explore virus diversity and ecology in individual plants and pooled samples of two grass species, Lolium perenne and Poa trivialis, from pastures and high biological value grasslands. Using a virion-associated nucleic acids (VANA) metagenomic approach on 143 individual plants, the study found for both host species a higher virus prevalence (79%) in pastures, dominated by phytoviruses, whereas grasslands showed lower virus prevalence (48%), with a predominance of mycoviruses. High prevalence of co-infected plants was observed but with low virus accumulation. For yellow dwarf viruses (B/CYDVs), comparison of sequenced genomes within and between plants suggested a high genetic diversity, and a novel BYDV-like species was identified in Poa trivialis. Additionally, Lolium perenne was identified as a key virus reservoir, hosting up to 25 different virus species compared Poa trivialis infected by up to 16 viruses. These findings underscore the significant role of wild plant communities as virus reservoirs, influencing virus ecology across both natural and agricultural landscapes
Tunable anharmonicity in cavity optomechanics in the unresolved sideband regime
No full textInternational audienceIntroducing a controlled and strong anharmonicity in mechanical systems is a present challenge of nanomechanics. In cavity optomechanics a mechanical oscillator may be made anharmonic by ponderomotively coupling its motion to the light field of a laser-driven cavity. In the regime where the mechanical resonating frequency and the single-photon coupling constant are small compared to the decay rate of the cavity field, it turns out that the quantum electromagnetic fluctuations of the laser field drive the oscillator into a high-temperature thermal state. The motional state may however be highly non-Gaussian; we show that a precise tuning of system parameters may even lead to a purely quartic effective potential for the mechanical oscillator. We present a theory that predicts the measurable signatures left by the mechanical anharmonicity. In particular, we obtain analytically and numerically the mechanical displacement spectrum, and explore the imprints of the mechanical anharmonicity on the cavity light field
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No full texthttps://bioarcheo.hypotheses.org/388
European governance of climate-related mobility: a security obsession?
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Quantifying fluvial abrasion in Ishango (D.R. Congo) and its impact on the study of human behaviour
No full textInternational audienceOpen-air sites present unique challenges for bone cortical surface preservation due to prolonged exposure to multiple taphonomic agents. Fluvial contexts, common across Africa, are particularly impactful, as currents alter both the spatial distribution and cortical surfaces of osteological remains. The site of Ishango (≈20 ka, D.R. Congo) lies within the Semliki River fluvial complex on the shore of Lake Mutsyamira. Occupied primarily by fishing populations during the Late Pleistocene, Ishango holds critical importance in studying Late Stone Age technology and cognition. Its exceptional bone tool assemblage includes harpoons, fishing implements, and several engraved objects whose interpretation is currently under debate. The renowned Ishango rod, presenting a large number of markings organised in spatially distinct sets, has been interpreted by some as recording evidence of advanced numerical cognition. Fluvial taphonomic processes—abrasion, polishing, and rounding—complicate the analysis of these features, hinder the reconstruction of chaînes opératoires, and thus difficult the interpretation of many artefacts. Surface texture analysis, using confocal microscopy and roughness parameters, provide new quantitative insights into these processes. This study identifies the impact of fluvial abrasion on the Ishango assemblage, offering a novel approach to assessing taphonomic processes, and their influence on interpreting past behavioural, cultural and cognitive practices
Analyse morphométrique 3D de la croissance et du développement de la base du crâne chez l’Homme moderne
No full textInternational audienceLa base du crâne est une zone anatomique unique par sa localisation, sa croissance spécifique et son rôle d’interface entre trois fonctions majeures qui définissent l’homme moderne : un appareil masticateur gracile, un neurodéveloppement important et une locomotion bipède. Sur le plan topographique, la base du crâne se divise en trois segments : la fosse crânienne antérieure formée par l’éthmoïde et le frontal, la fosse crânienne moyenne formée par le sphénoïde et la fosse crânienne postérieure formée majoritairement par l’occipital. Sur le plan développemental, la base du crâne est également une structure particulière car elle s’ossifie de façon enchondrale, à partir d’un squelette cartilagineux appelé chondrocrâne qui porte une forte empreinte génétique. On imagine donc aisément que la base du crâne, par sa position anatomique stratégique, a joué un rôle significatif au cours de l’évolution, notamment dans les processus d’encéphalisation, de réduction de la face et de modification de l’appareil masticatoire, ainsi que dans l’évolution des relations topographiques entre le crâne et le rachis. Au cours de ce travail, 208 CT-scans d’enfants âgés de 0 à 15 ans ont été étudiés en morphométrie géométrique pour analyser les trajectoires de croissance des trois fosses de la base du crâne. Les résultats ont montré l’existence de trois phases distinctes : un fort taux de croissance entre 0 et 2 ans, une diminution progressive de ce taux jusqu’à 6 à 7 ans, puis une croissance très faible jusqu’à l’adolescence. Les analyses ont également montré que la croissance transversale de la base du crâne est la plus importante, notamment dans la partie postérieure des grandes ailes du sphénoïde.Enfin, nous avons mis en évidence une forte allométrie de croissance, ainsi qu’unAnalyse morphométrique 3D de la croissance et du développement de la base du dimorphisme sexuel qui est retrouvé sur le plan des dimensions mais pas au niveau de la conformation géométrique
De l’art à la technique : appréhender la sculpture pariétale par l’expérimentation. Application à la Vénus de Laussel (Dordogne, France)
No full textInternational audienceL’art paléolithique a longtemps été étudié par le prisme de la stylistique. L’examen de la production graphique et plastique, considérant les supports et les techniques d’exécution, n’a en effet été intégré que récemment et s’est particulièrement intéressé aux pièces mobilières.Notre étude vise ici à documenter la sculpture et la gravure pariétales d’un point de vue technique à partir de l’exemple de la Vénus à la corne de Laussel. Celle-ci a été découverte dansla Vallée de la Grande Beune (Dordogne, France), où de nombreux bas-reliefs ont été mis au jour. La sculpture pariétale paléolithique reste pourtant un phénomène rare et cette concentration localisée questionne l’existence de traditions artistiques.Dans un premier temps, différentes techniques proposées pour la mise en forme des représentations archéologiques (e.g. piquage, raclage, polissage, gravure) ont été expérimentées. Les traces expérimentales produites ont été décrites qualitativement et quantitativement par le biais de nouvelles méthodes. Réalisés avec un scanner surfacique, les modèles 3D ont permis de mieux comprendre les techniques mises en œuvre par l’étude des profils des incisions et des analyses de rugosité. Le traitement statistique de ces données tribologiques a permis de caractériser les techniques et les outils impliqués. Notre référentiel multiscalaire, allant des traces visibles à l’œil nu jusqu’à des caractères infra-millimétriques, pourra être utilisé comme outil de comparaison avec le registre archéologique.En considérant les productions symboliques comme des objets techniques, la sculpture devient un champ de recherche permettant de questionner l’économie des groupes humains