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Tracking surface ozone responses to clean air actions under a warming climate in China using machine learning
No full textInternational audienceSurface ozone, a major air pollutant with important implications for air quality, ecosystems, and climate, shows long-term trends shaped by both anthropogenic and climatic drivers. Here, we developed a machine learning-based approach, namely the fixed emission approximation (FEA), to decouple the effects of meteorological variability and anthropogenic emissions on summertime ozone trends in China under the clean air actions. Anthropogenic emissions drove an approximately +23.2 ± 1.1 µg m -3 increase in summer maximum daily 8 h average ozone during 2013-2017, followed by an approximately -4.6 ± 1.5 µg m -3 decrease between 2017 and 2020 in response to strengthened emission controls. In contrast, meteorological anomalies, including heatwaves and rainfall conditions, emerged as substantial drivers of ozone variability during 2020-2023. Satellite-derived formaldehyde-to-nitrogen dioxide ratios revealed widespread urban volatile organic compounds-limited regimes for ozone production, with a shift toward nitrogen oxides-limited sensitivity under influence of heatwaves. Extending the FEA framework to assess long-term climate influences from 1970 to 2023, we find that sustained climate warming has driven a substantial increase in urban summertime ozone in China. These results demonstrate that climate change was increasingly offsetting the benefits of emission reductions and highlight the need for integrated ozone mitigation strategies that jointly address emission controls and climate adaptation in a warming world.</div
Observation of violation in decays
No full textInternational audienceThe time-dependent asymmetry in decays is measured using proton-proton collision data corresponding to an integrated luminosity of , collected with the LHCb detector at a center-of-mass energy of during the years 2015-2018. The -violation parameters for this process are determined to be and , where the first uncertainty is statistical and the second systematic. This constitutes the first observation of time-dependent violation in meson decays to charmonium final states mediated by a transition. These results are consistent with, and two times more precise than, the previous LHCb measurement based on a data sample collected at 7 and corresponding to an integrated luminosity of . Assuming approximate SU(3) flavor symmetry, these two measurements are combined to set the most stringent constraint on the enguin contribution, , to the -violating phase in decays, yielding
Full event interpretation with machine-learning-based particle-flow reconstruction in the CMS detector
No full textInternational audienceThe particle-flow (PF) algorithm constructs a global description of each particle collision by producing a comprehensive list of final-state particles, and is central to event reconstruction in the CMS experiment at the CERN LHC. The existing PF implementation relies on physics-motivated heuristics and assumptions that can be replaced by machine-learning (ML) models trained directly on simulated data and naturally suited to modern graphics processing units (GPUs). A state-of-the-art ML-based PF (MLPF) reconstruction algorithm, implemented within the CMS software framework, is presented. The MLPF algorithm performs a learnable full-event reconstruction on GPUs, generalizes across detector conditions and collision energies, and replaces multiple modular reconstruction steps with a single unified model. Physics performance comparable to standard PF reconstruction is achieved in both simulation and data, with improved jet energy resolution and inference time. In simulated top quark-antiquark events under LHC Run-3 (20232024) conditions, the jet energy resolution improves by 1020% for jets with transverse momentum between 30100 GeV. Inference time is evaluated using simulated multijet events, with a median of 20 ms per event on an Nvidia L4 GPU, compared to approximately 110 ms for the standard CMS PF reconstruction
Exact Multiple Change-Point Detection Via Smallest Valid Partitioning
No full textWe introduce smallest valid partitioning (SVP), a segmentation method for multiple change-point detection in time-series. SVP relies on a local notion of segment validity: a candidate segment is retained only if it passes a user-chosen validity test (e.g., a single change-point test). From the collection of valid segments, we propose a coherent aggregation procedure that constructs a global segmentation which is the exact solution of an optimization problem. Our main contribution is the use of a lexicographic order for the optimization problem that prioritizes parsimony. We analyze the computational complexity of the resulting procedure, which ranges from linear to cubic time depending on the chosen cost and validity functions, the data regime and the number of detected changes. Finally, we assess the quality of SVP through comparisons with standard optimal partitioning algorithms, showing that SVP yields competitive segmentations while explicitly enforcing segment validity. The flexibility of SVP makes it applicable to a broad class of problems; as an illustration, we demonstrate robust change-point detection by encoding robustness in the validity criterion
Compendium on Monte Carlo simulation of photoneutrons in the Giant Dipole Resonance energy range
No full textInternational audienc
Approches méthodologiques croisées : hexis et élicitation-interview
No full textInternational audienceThis article examines the use of elicitation interviews for the analysis of hexis based on image-based media, drawing on cross-methodological approaches. Christine Louveau de la Guigneraye presents an exploratory study based on videoethnographic work for an R&D firm on the behaviour of car drivers in 2006, while Fabienne Duteil-Ogata presents a survey on the representation of the body of Japanese sports students based on their phoneographies posted on Instagram in 2017. After an essential reminder of the respective context of the two studies, a cross analysis of the body in gesture and gestures in body declined on four levels (look, physiognomy, gesture and posture) highlights the contributions of elicitation according to three levels (the interviewee, the researcher and the interviewed relationship): a rebalancing of the researcher-interviewee relationship, the co-construction of data and the prominence of paralanguage.Cet article interroge l’usage de l’élicitation interview pour l’analyse de l’hexis à partir de supports imagétiques en s’appuyant sur des approches méthodologiques croisées. Christine Louveau de la Guigneraye y présente une étude exploratoire sur la base d’un travail vidéoethnographique pour un cabinet de R&D sur le comportement des conducteurs transiliens en 2006 tandis que Fabienne Duteil-Ogata expose une enquête sur la représentation du corps d’étudiants japonais sportifs d’après leurs phonéographies postées sur Instagram en 2017. Après un rappel indispensable du contexte respectif des deux recherches, une analyse croisée du corps en geste et gestes en corps décliné sur quatre plans (regard, physionomie, geste et posture) met en évidence les apports de l’élicitation selon trois niveaux (l’interviewé, le chercheur et la relation avec l’interviewé) : un rééquilibrage de la relation chercheur-interviewé, la co-construction des données et la prégnance du paralangage
Holograph: a generic RDF schema to handle data from agroecological holobionts
No full textInternational audienceManaging and integrating metagenomic data is a key challenge in holobiont studies, as understanding host–microbiota interactions requires linking complex heterogeneous datasets, such as microbial diversity, host phenotype, and environmental context. In response, Holograph, an RDF schema dedicated to the representation of holobiont data, has been developed to provide a structured and interoperable way to store such heterogeneous information. It includes a central part dedicated to handle metabarcoding data, i.e. abundance tables of Amplicon Sequence Variants, which is connected to various descriptors, called features of interest, of the host itself or its environment. Observations and variables related to the host are handled with an implementation of the SOSA and I-ADOPT ontologies. In addition, the GeoSPARQL ontology is used to define complex spatial relationships between the locations of features of interest such as the biological compartment where the sample has been extracted, the corresponding host (e.g plant) and geographical information (e.g. plot where the plant is cultivated and the field containing the plot). As a result, this generic schema was applied to integrate the data from a large case study covering metagenomics, biochemical assays, bioagressors description, climatic and phenotypic data. Furthermore, the Holograph's schema is also currently implemented on livestock holobionts datasets and can be queried with a dedicated web-interface
CTAO LST-1 observations of magnetar SGR 1935+2154: Deep limits on sub-second bursts and persistent tera-electronvolt emission
No full textInternational audienceThe Galactic magnetar SGR 1935+2154 has exhibited prolific high-energy (HE) bursting activity in recent years. Investigating its potential tera-electronvolt counterpart could provide insights into the underlying mechanisms of magnetar emission and very high-energy (VHE) processes in extreme astrophysical environments. We aim to search for a possible tera-electronvolt counterpart to both its persistent and sub-second-scale burst emission. We analysed over 25 h of observations from the Large-Sized Telescope prototype (LST-1) of the Cherenkov Telescope Array Observatory (CTAO) during periods of HE activity from SGR 1935+2154 in 2021 and 2022 to search for persistent emission. For bursting emission, we selected and analysed nine 0.1 s time windows centred around known short X-ray bursts, targeting potential sub-second-scale tera-electronvolt counterparts in a low-photon-statistics regime. While no persistent or bursting emission was detected in our search, we establish upper limits for the tera-electronvolt emission of a short magnetar burst simultaneous to its soft gamma-ray flux. Specifically, for the brightest burst in our sample, the ratio between tera-electronvolt and X-ray flux is less than . The non-detection of either persistent or bursting tera-electronvolt emission from SGR 1935+2154 suggests that if such components exist, they may occur under specific conditions not covered by our observations. This aligns with theoretical predictions of VHE components in magnetar-powered fast radio bursts and the detection of MeV - GeV emission in giant magnetar flares. These findings underscore the potential of magnetars, fast radio bursts, and other fast transients as promising candidates for future observations in the low-photon-statistics regime with Imaging Atmospheric Cherenkov Telescopes, particularly with the CTAO
Balancing positive and negative environmental impacts of urban greening considering future climate: A case study in the Paris region, France
No full textInternational audienceUrban greening enhances summer thermal comfort in cities; however, vegetation requires watering and reduces solar gains on buildings, potentially increasing energy consumption for heating. A methodology was developed to investigate whether the positive effects of urban trees on human health offset the increased water and energy consumption impacts. This method involves four steps: 1. Modelling the urban microclimate based on regional climatic data, accounting for vegetation effects; 2. Evaluating indoor temperatures and possible overheating using building thermal simulation; 3. Deriving the damage of overheating on human health, and 4. Performing a life cycle assessment.This process was applied to a case study on an urban greening project, including renovating an existing social housing building. According to the results, urban greening thanks to trees allows a decrease in outdoor air temperature around 1.7 • C (median value, 1.3 • C and 2.0 • C for 10th and 90th percentile, resp.) and a decrease in indoor temperature around 0.4 • C (median value; 0.25 • C and 0.55 for 10th and 90th percentile, resp.) during the five weeks heat wave period. Some life-cycle environmental impacts were reduced, particularly those related to damage to human health (-12.5 %), with limited impact transfer. The impact reduction due to energy savings from building renovation is higher.While many cities invest in urban greening projects, the importance of energy renovation is often overlooked. This prioritisation may be questioned, and the analysis presented in this article could serve as a valuable tool in guiding decision-making. By using the same indicator (Disability-Adjusted Life Years, DALY) to express life cycle and overheating-related impacts, this approach enables the integration of mitigation and adaptation in decisionmaking processes
Smart Digital Environments for Monitoring Precision Medical Interventions and Wearable Observation and Assistance
No full textInternational audienceVarious recurring medical events encourage innovative patient well-being through connected health strategies based on an elegant digital environment that prioritizes safety, comfort, and beneficial outcomes for both patients and medical staff. This narrative review article aims to investigate and highlight the potential of advanced, reliable, high-precision, and secure medical observation and intervention missions. These involve a smart digital environment integrating smart materials combined with smart digital monitoring. These medical implications concern robotic surgery and drug delivery through image-assisted implantation, as well as wearable observation and assistive tools. The former requires high-precision motion and positioning strategies, while the latter enables sensing, diagnosis, monitoring, and central task assistance. Both advocate minimally invasive or noninvasive procedures and precise supervision through autonomously controlled processes with staff participation. The article analyzes the requirements and evolution of medical interventions, robotic actuation technologies for positioning actuated and self-moving instances, monitoring of image-assisted robotic procedures using digital twins and augmented digital tools, and wearable medical detection and assistance devices. A discussion including future research perspectives and conclusions complete the article. The different themes addressed in the proposed paper, although self-sufficient, are supported by examples of the literature, allowing a deeper understanding