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Centrophilic retrotransposon integration via CENH3 chromatin in Arabidopsis
No full textInternational audienceIn organisms ranging from vertebrates to plants, major components of centromeres are rapidly evolving repeat sequences, such as tandem repeats (TRs) and transposable elements (TEs), which harbour centromere-specific histone H3 (CENH3)1,2. Complete centromere structures recently determined in human and Arabidopsis suggest frequent integration and purging of retrotransposons within the TR regions of centromeres3,4,5. Despite the high impact of ‘centrophilic’ retrotransposons on the paradox of rapid centromere evolution, the mechanisms involved in centromere targeting remain poorly understood in any organism. Here we show that both Ty3 and Ty1 long terminal repeat retrotransposons rapidly turnover within the centromeric TRs of Arabidopsis species. We demonstrate that the Ty1/Copia element Tal1 (Transposon of Arabidopsis lyrata 1) integrates de novo into regions occupied by CENH3 in Arabidopsis thaliana, and that ectopic expansion of the CENH3 region results in spread of Tal1 integration regions. The integration spectra of chimeric TEs reveal the key structural variations responsible for contrasting chromatin-targeting specificities to centromeres versus gene-rich regions, which have recurrently converted during the evolution of these TEs. Our findings show the impact of centromeric chromatin on TE-mediated rapid centromere evolution, with relevance across eukaryotic genomes
Weak conditional propagation of chaos for systems of interacting particles with nearly stable jumps
No full textInternational audienceWe consider a system of interacting particles, described by SDEs driven by Poisson random measures, where the coefficients depend on the empirical measure of the system. Every particle jumps with a jump rate depending on its position. When this happens, all the other particles of the system receive a small random kick which is distributed according to a heavy-tailed random variable belonging to the domain of attraction of an -stable law and scaled by where 0 < α < 2. We call these jumps collateral jumps. Moreover, in case 0 < α < 1, the jumping particle itself undergoes a macroscopic, main jump. Such systems appear in the modeling of large neural networks, such as the human brain. Using a representation of the collateral jump sum as a time-changed random walk, we prove the convergence in law, in Skorokhod space, of this system to a limit infinite-exchangeable system of SDEs driven by a common stable process. This stable process arises due to the stable central limit theorem, and the particles in the limit system are independent and identically distributed, conditionally on that. That is, the -particle system exhibits the conditional propagation of chaos property
Le travail de la donnée au sein d'une administration : recomposition, valorisation et dévalorisation
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Counting Work and Workers in Africa: Introduction to the Special Issue
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Reversible self-assembly of small molecules for recyclable solid-state battery electrolytes
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Global atmospheric inversion of the anthropogenic NH<sub>3</sub> emissions over 2019–2022 using the LMDZ-INCA chemistry transport model and the IASI NH<sub>3</sub> observations
No full textInternational audienceAmmonia (NH 3 ) emissions have been on a continuous rise due to extensive fertilizer usage in agriculture and increasing production of manure and livestock. However, the current global-to-national NH 3 emission inventories exhibit large uncertainties. We provide atmospheric inversion estimates of the global NH 3 emissions over 2019-2022 at 1.27°× 2.5°horizontal and daily (at 10 d scale) resolution. We use IASI-ANNI-NH3-v4 satellite observations, simulations of NH 3 concentrations with the chemistry transport model LMDZ-INCA, and the finite difference mass-balance approach for inversions of global NH 3 emissions. We take advantage of the averaging kernels provided in the IASI-ANNI-NH3-v4 dataset by applying them consistently to the LMDZ-INCA NH 3 simulations for comparison to the observations and then to invert emissions. The average global anthropogenic NH 3 emissions over 2019-2022 are estimated as ∼ 97 (94-100) Tg yr -1 , which is ∼ 61 % (∼ 55 %-65 %) higher than the prior Community Emissions Data System (CEDS) inventory's anthropogenic NH 3 emissions and significantly higher than two other global inventories: CAMS's anthropogenic NH 3 emissions (by a factor of ∼ 1.8) and the Calculation of AMmonia Emissions in ORCHIDEE (CAMEO) agricultural and natural soil NH 3 emissions (by ∼ 1.4 times). The global and regional budgets are mostly within the range of other inversion estimates. The analysis provides confidence in their seasonal variability and continental-to regional-scale budgets. Our analysis shows a rise in NH 3 emissions by ∼ 5 % to ∼ 37 % during the COVID-19 lockdowns in 2020 over different regions compared to the same-period emissions in 2019. However, this rise is probably due to a decrease in atmospheric NH 3 sinks due to the decline in NO x and SO 2 emissions during the lockdowns.</div
A Multimodal Sensing-Driven Smart Shoe System for Gait Phase Recognition in Exoskeleton Applications
No full textInternational audienceTo enhance the precision and naturalness of exoskeleton control, this paper proposes a novel multimodal smart shoe design for precise gait analysis. Unlike conventional gait models that rely solely on kinematic data, our system integrates foot pressure distribution and foot deformation sensing to construct a more comprehensive foot motion model. The smart shoe is equipped with inertial measurement units (IMUs), a plantar pressure sensor and bending sensors. Multimodal data was collected and analyzed to extract gait features including trajectory, pressure distribution, and foot deformation patterns. A multimodal gait analysis model was developed using sensor fusion techniques. Experimental results demonstrate that the proposed system provides a more accurate and holistic representation of foot motion, offering enhanced biomechanical and dynamic information for future exoskeleton control systems
Meiofauna investigation and taxonomic identification through imaging—a game of compromise
No full textInternational audienceImaging methods have developed rapidly in recent decades, opening new opportunities for taxonomy and biodiversity studies of marine organisms. In particular, the microscopic size range, which used to be challenging to study due to time‐consuming preparation and observation steps, now benefits from high‐throughput quantitative imaging methods and the development of fast high‐resolution microscopy approaches. Meiofauna, interstitial sediment animals ranging from 20 μ m to 1 mm, are important components of ecosystems. These organisms can serve as bioindicators, and the group as a whole holds immense potential for the discovery of new species. However, protocols for studying meiobenthos are highly time‐consuming, which helps explain why this group is understudied. We tested five imaging techniques, ranging from low to high resolution, that could accelerate hard‐bodied meiofauna studies, both for ecology and species description, and address the gap in our understanding of this part of marine life. Thus, two flow imaging modalities (in line holographic microscopy and classic optic microscopy), a semi‐automated microscopy acquisition procedure, and two three‐dimensional (3D) fluorescence microscopy protocols were used. We examined the classic compromises of imaging, including resolution, throughput, and data volume, to evaluate the potential benefits of using such techniques for meiofaunal studies. For ecological surveys, flow imaging could benefit meiobenthos studies, but resolution remains a limiting factor. For taxonomic description, 3D fluorescent imaging added relevant information, considering the time required for preparation and acquisition. The semi‐automated motorized microscopy procedure could be used for both purposes according to the versatility of the system
Une plateforme d'apprentissage collaboratif combinant le co-embodiment et la co-manipulation kinesthésique pour l'acquisition de comptétences techniques en réalité virtuelle
No full textInternational audienceWe propose a demonstration of a virtual reality platform for learning technical gestures. With this platform, an expert can guide a learner during their training. The guidance is visual through the co-embodiment of a single virtual avatar shared between the two users and also a kinesthetic co-manipulation link thanks to two haptic interfaces. The system will be used to explore the impact of the connection between the learner and the teacher on the long-term retention of a technical skill.Nous proposons la démonstration d’une plateforme d’apprentissage de gestes techniques en réalité virtuelle. Avec cette plateforme, un expert peut guider un apprenant dans lors de son entrainement. Le guidage est visuel au travers de la co-incarnation d’un seul avatar virtuel partagé entre les deux utilisateurs et également kinesthésique grâce à deux interfaces à retour d’effort. Le dispositif servira à explorer l’impact du lien entre apprenant et expert pour la rétention à long terme d’un geste technique
