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Lake sedimentation rate represents a synthetic metric of ecosystem functioning. Many localized studies have reported a significant association between land use/land cover changes and lake sediment mass accumulation rates, with a few global syntheses echoing these findings at larger scales. In the literature, studies evaluating lead-210 (Pb-210) for establishing sediment chronologies will report at least one of three dating models, but the constant rate of supply (CRS) model is the most widely used. However, it is often unclear how or why this model is selected, despite its influence on the interpretation of many subsequent analyses about ecosystem dynamics and functioning. It would thus be advantageous to design an objective and semi-automated way of choosing among dating models. We measured radioisotopic activities in 37 sediment cores across four ecozones of Eastern Canada and developed an approach to assess model fit for the three commonly applied dating models. The derived chronologies were then used to evaluate the spatial and temporal variation in sedimentation rates across four ecozones in Canada (covering a surface area of 2.2 x 10(6) km(2)). We observed a recent increase in lake sedimentation rates across most lakes, as has been observed globally, albeit with significant differences in the magnitude of sedimentation rates across ecozones. Across all lakes, we found that regional human population counts and mean annual air temperatures were significant temporal predictors of variation in mass accumulation rates. Overall, this analytical framework offers an objective approach for assessing fit and selecting among sediment age models, which contributes to a more robust quantification of sedimentation rates. With this first application, we provide a quantitative assessment of how lake sedimentation rates have varied across a northern lake-rich region and have responded to environmental change.

In high rapidity regions of experiments at colliders (e.g. Large Hadron Collider LHC), along the direction of the interacting beams, the conditions are particularly challenging and the detectors need to have excellent time resolution, spatial resolution, high-rate capability and radiation resistance. Among various detector schemes proposed for these applications, combinations of Cherenkov radiators (quartz, sapphire, etc.) with fast photodetectors (e.g. Micro Channel Plate PMT (MCP PMT), Silicon PM (SiPM)) have been studied. Quartz-based calorimeters are already employed at CMS (Compact Muon Solenoid) experiment in the forward direction. Quartz bar array detectors were initially proposed as timing elements for the CT-PPS (CMS-TOTEM Precise Proton Spectrometer) project. We report here on the performance of one of these QUARTIC (QUARtz TIming Cherenkov) detectors, which was installed in 2018 (as test prototype) in the CMS Forward Zone near the CMS beam pipe.

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La technique chirurgicale de la membrane induite décrite par Masquelet semble offrir une solution thérapeutique efficace dans la gestion des larges pertes de substance osseuse du membre inférieur chez l’adulte, avec des taux de consolidation satisfaisants, malgré de nombreuses complications post-opératoires, en particulier infectieuses. Notre étude a permis de démontrer son efficacité aussi bien dans la prise en charge des fractures que dans la gestion des pseudarthroses diaphysaires du tibia ou du fémur. Il semblerait que cette intervention soit plus efficace en termes de délai de consolidation au niveau du fémur qu’au niveau du tibia.A l’heure actuelle, de nombreuses questions restent en suspens. Existe-t-il une technique chirurgicale plus efficace que la technique chirurgicale de la membrane induite décrite par Masquelet ? Comme nous l’avons vu précédemment, cette intervention semble moins efficace au niveau du tibia (délai de consolidation plus long qu’au niveau du fémur). Dans ce cas-là, qu’elle est la place des autres techniques chirurgicale comme celle d’Ilizarov et du transport osseux, plus ou moins associée à un enclouage centromédullaire ? Quelle est la meilleure greffe osseuse et quelle est la place des substituts osseux et des substances ostéogéniques dans la technique chirurgicale de la membrane induite ? La tendance actuelle, nous oriente vers des greffes combinées (autogreffe osseuse, allogreffe morcelée, substitut osseux et facteurs de croissance) permettant de répondre aux conditions requises par le « Diamond concept ». Toutes ces questions ouvrent la voie à de nombreuses recherches pour optimiser la prise en charge des larges pertes de substance osseuse.