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Global biogenic isoprene emissions 2013-2020 inferred from satellite isoprene observations
No full textInternational audienceIsoprene, the most emitted biogenic volatile organic compound, exerts a remarkable influence on atmospheric oxidation capacity, air quality, and climate. Most existing top-down atmospheric estimates of isoprene emissions rely on observational formaldehyde (HCHO) as an indirect proxy, even though HCHO is produced from multiple precursors. Recent advances in satellite retrievals of isoprene concentrations from the Crosstrack Infrared Sounder (CrIS) enable a direct constraint on isoprene emission inversions. Yet global, multi-year isoprene-based atmospheric inversions are still lacking. Here, we present global, monthly biogenic isoprene emission maps spanning 2013-2020, derived from a mass-balance inversion framework that assimilates CrISretrieved isoprene columns into the LMDZ-INCA chemistry-transport model. The global biogenic isoprene emissions average is of 456 ± 238 Tg C yr -1 over 2013-2020, which is broadly consistent with existing inventories and HCHO-based inversion estimates. The LMDZ-INCA simulations using this estimate of the emissions exhibit improved spatial agreement and reduced biases relative to two independent satellite HCHO retrieval products and to ground-based optical measurements, confirming the robustness of this inversion framework. The seasonal cycle of emissions is dominated by the Northern Hemisphere, driven by the strong seasonality in temperature and vegetation biomes. Interannually, emissions vary by on average 14 Tg C yr -1 (1-sigma standard deviation). Two major emission peaks are found in 2015-2016 (456 Tg C yr -1 ) and 2019-2020 (478 Tg C yr -1 ), coinciding with El Niño and widespread extreme heat-wave events, underscoring the dominant influence of temperature anomalies that increase biogenic emissions. Regional analyses identify the Amazon as the largest contributor to the interannual variability, accounting for 22.3 % of the global interannual variance in isoprene emissions. Temperature emerges as the primary driver of regional interannual emissions, with its influence modulated by leaf area index and radiation to varying degrees across regions. As one of the earliest attempts at a global, multi-year inversion based on isoprene observations, this dataset provides input for air quality and climatechemistry models.</div
A System Reanalysis of the Current Greenhouse Gases Budget of Terrestrial Ecosystems in Russia
No full textInternational audienceThis study synthesizes the budgets of three greenhouse gases (GHG, namely CO 2 , CH 4 , N 2 O) for Russia over two decades (2000-2009 and 2010-2019) using bottom-up and top-down approaches, as part of the Regional Carbon Cycle Assessment and Processes, Phase 2 (RECCAP2). Published estimates of natural sources and sinks of these GHGs in Russia vary widely. Here, bottom-up estimates are based on eddy covariance measurements, the Integrated Land Information System of Russia (ILIS-LEA), field data, Dynamic Global Vegetation Models (DGVMs), and regional models. The bottom-up approach estimated Net Ecosystem Exchange (NEE) at 0.64 ± 0.17 and 0.57 ± 0.14 Pg C yr 1 , for decades 2000-2009 and 2010-2019, respectively. Top-down atmospheric inversions provide similar NEE carbon flux estimates with comparable uncertainties at 0.56 ± 0.26 and 0.73 ± 0.27 Pg C yr 1 for the two decades. Differences between these approaches arise from distinct flux components and structural assumptions. ILIS-LEA indicates a slightly declining carbon sink in 2010-2019, driven by increased disturbances. In contrast, DGVMs suggest a stable carbon sink over both decades but they do not fully simulate the effects of disturbances and recovery. Top-down inversions reveal an increasing CO 2 sink, suggesting with additional observed constraints on biomass carbon increment that soil and non-forest biomes absorb more carbon than predicted by DGVMs and ILIS-LEA models. A Bayesian averaging approach estimates natural ecosystems acting as a GHG sink with a land-toatmosphere flux of 1.55 ± 0.91 and 1.47 ± 0.82 Pg CO 2 -eq. yr 1 . Accounting for both natural and anthropogenic emissions across the Russian territory shifts the net GHG balance to a source around 1.2 Pg CO 2eq. yr 1 .</div
How does humidity affect lidar-derived aerosol optical properties, and how do they compare with CAMS?
No full textInternational audienceand during summer 2024, aerosol backscatter and relative humidity profiles were measured near Paris region using the Water Vapour and Aerosol Lidar (WALI). The campaigns included observations on the Saclay plateau (48°42 42 N, 02°08 52 E) and in Paris (48°50 12 N, 02°20 10 E) during the 2024 Olympic Games. The high vertical (15 m) and temporal (15 min) resolution of WALI allow to study aerosol optical properties and water vapour profiles under stable atmospheric conditions. This study focuses on characterizing aerosol hygroscopic growth using lidar-derived aerosol backscatter coefficients as a function of relative humidity. Eight case studies were selected where the potential temperature gradient was neutral and the water vapor mixing ratio was constant with height. These include long range air pollution transport from the Benelux region, low hygroscopic aerosol events, and a sea salt-pollution mixture episode. Hygroscopicity was assessed using CAMS model analyses and reanalyses, allowing attribution of chemical composition to observed optical changes. Good agreement was found between lidar-derived hygroscopic properties and CAMS-inferred aerosol types. Lidar growth factors ranged from 0.3 to 1.5, with higher values linked to sea salt presence, consistent with literature values. Aerosols hygroscopicity is also studied using Mie's theory, as aerosols can be considered nearly spherical. Differences between extinction and backscatter-based growth retrievals are interpreted through Hänel's formalism. The results illustrate the potential of Raman lidar observations to provide valuable constraints on aerosol hygroscopicity, offering complementary information for chemistry-transport models and contributing to reduce uncertainties in aerosolcloud interaction estimates.</div
Les recompositions d’un métier « voué à disparaitre » : les usages du numérique par les secrétaires et assistantes dans des organisations en changement.
No full textInternational audienc
Land use-induced soil carbon loss in the dry tropics nearly offsets gains in northern lands
No full textInternational audienceSoil carbon changes are difficult to measure globally, and global models are poorly constrained. Here, we propose a framework to map annual changes in soil carbon and litter (SOCL) as the difference between the net land CO 2 flux from atmospheric inversions and satellite-based maps of biomass changes. We show that SOCL accumulated globally at a rate of about 0.34 ± 0.30 ( ± 1 sigma) billion tonnes of carbon per year (PgC yr -1 ) during 2011-2020. The largest SOCL sink is found in boreal regions (0.93 ± 0.45 PgC yr -1 in total) particularly in undisturbed peatlands and managed forests. The largest losses occur in the dry tropics (-0.50 ± 0.47 PgC yr -1 ) and correspond with agricultural expansion from land use change, cropland management and grazing. By contrast, forests in the wet tropics act as a net soil carbon sink (0.32 ± 0.35 PgC yr -1 ). Our findings highlight the large mitigation opportunities in the dry tropics to restore agricultural soil carbon.Global changes in fossil fuel and cement CO 2 emissions, the atmospheric CO 2 growth rate and net land carbon fluxes have been reasonably quantified in global carbon budget analyses 1-3 . However, more accurate partitioning of the global land carbon sink into biomass and soil carbon (SOC) changes is still needed 4 . Soils represent the largest terrestrial carbon pool 5 , but a substantial fraction of it, like deep peat deposits 6 , does not actively exchange carbon with the atmosphere. Given the size of the soil carbon pool, even if a small fraction is lost, it could result in a strong decline of the current land carbon sink 7 . Earth System Model projections of soil carbon changes are very uncertain, ranging from a large source to a sustained sink in the future 8 . Mapping current soil carbon changes and attributing them to land use versus</div
Spironolactone in patients on chronic haemodialysis at high risk of adverse cardiovascular outcomes (ALCHEMIST): a multicentre, double-blind, randomised, placebo-controlled trial and updated meta-analysis
No full textInternational audienceNo pharmacological therapy has been shown with certainty to improve the cardiovascular prognosis in patients with kidney failure on chronic haemodialysis. We aimed to investigate the effects of the steroidal mineralocorticoid receptor antagonist spironolactone on cardiovascular outcomes in patients on haemodialysis who are at high risk of cardiovascular events.MethodsALCHEMIST was an investigator-initiated, multicentre, double-blind, randomised, placebo-controlled, event-driven trial conducted at 64 university hospitals, general hospitals, and non-profit or private practice dialysis centres in France, Belgium, and Monaco. Adult patients aged 18 years and older with kidney failure on chronic haemodialysis with at least one cardiovascular comorbidity or risk factor were enrolled into a 4-week run-in period on open-label oral spironolactone 25 mg every other day. Participants were randomly assigned (1:1) to oral spironolactone titrated to 25 mg per day or placebo. The randomisation sequence was computer generated and stratified by centre in blocks of 4 or 6, and permutation of treatments within each block. The random assignment was double-blinded. The primary endpoint was time to first major adverse cardiovascular event (cardiovascular death, non-fatal myocardial infarction, acute coronary syndrome, stroke, or hospitalisation for heart failure) and was analysed in the intention-to-treat population. We also performed an updated meta-analysis of double-blind, randomised controlled trials of mineralocorticoid receptor antagonists in patients on haemodialysis incorporating data from ALCHEMIST. The study was registered with ClinicalTrials.gov, NCT01848639.FindingsBetween June 13, 2013, and Nov 24, 2020, 1442 patients were locally screened for eligibility. 823 patients were included in the trial and 794 entered the run-in period. 644 patients were randomly assigned to spironolactone (n=320) or placebo (n=324). 444 (69%) patients were men and 200 (31%) were women. The trial was stopped prematurely due to lack of funding from the sponsor. Median follow-up was 32·6 months (IQR 17·3–48·4). The primary endpoint occurred in 78 (24%) of 320 patients in the spironolactone group (10·66 per 100 patient-years [95% CI 8·54–13·31]) and 79 (24%) of 324 patients in the placebo group (10·70 per 100 patient-years [8·59–13·35]; hazard ratio [HR] 1·00 [95% CI 0·73–1·36]; p=0·98). Hyperkalaemia above 6 mmol/L was reported in 135 (42%) patients in the spironolactone group and 134 (41%) in the placebo group (HR 1·12 [95% CI 0·88–1·43]). In the meta-analysis, mineralocorticoid receptor antagonists did not reduce all-cause or cardiovascular mortality or non-fatal cardiovascular events and did not increase the odds of hyperkalaemia events (serum potassium concentration >6 mmol/L).InterpretationIn patients with kidney failure on haemodialysis and with high risk of adverse cardiovascular outcomes, spironolactone did not reduce the incidence of major cardiovascular events. The updated meta-analysis shows that mineralocorticoid receptor antagonists did not reduce all-cause or cardiovascular mortality. Therefore, off-label use of spironolactone in this setting is not supported by available evidence
A linear model of separation for western boundary currents with bathymetry
No full textThis paper is devoted to the asymptotic analysis of strongly rotating and stratified fluids, under a -plane approximation, and within a three-dimensional spatial domain with strong topography.Our purpose is to propose a linear idealized model, which is able to capture one of the key features of western boundary currents, in spite of its simplicity: the separation of the currents from the coast.Our simplified framework allows us to perform explicit computations, and to highlight the intricate links between rotation, stratification and bathymetry.In fact, we are able to construct approximate solutions at any order for our system, and to justify their validity.Each term in the asymptotic expansion is the sum of an interior part and of two boundary layer parts: a ``Munk'' type boundary layer, which is quasi-geostrophic, and an ``Ekman part'', which is not.Even though the Munk part of the approximation bears some similarity with previously studied 2D models, the analysis of the Ekman part is completely new, and several of its properties differ strongly from the ones of classical Ekman layers.Our theoretical analysis is supplemented with numerical illustrations, which exhibit the desired separation behavior
In vitro production significantly reduces metabolic differences among bovine embryos
No full textInternational audienceIntroduction Although the in vitro production of bovine embryos now exceeds in vivo production, the quality of in vitroproduced embryos remains inferior. Metabolomic analysis of the spent culture medium used for embryos is considered a relevant source of markers for subsequent developmental capacity, genetic status and sex. However, little is known about the sources of variability in this metabolome and their respective significance. Objective We compared bovine embryo spent culture media from in vivo developed (IVD) and in vitro produced (IVP) embryos, and analyzed how they varied with embryo stage, grade and sex. Methods Embryos were produced in vitro under two different conditions: SOF medium supplemented with 1% fetal calf serum or IVF Bioscience media, or developed in vivo. They were recovered at Day-6 and cultured individually for 26 hours. The culture medium was analyzed using 1H-NMR spectroscopy, and the embryos were staged, graded and sexed. Results In vitro production significantly reduced inter-embryo variability of the 24 metabolites measured. The mean variance of metabolite content was 5 to 10 times lower in IVP than in IVD embryos (depending on the IVP conditions). IVD embryo stages and grades at the start or end of the culture period contributed to 8% to 18% of variability in the media content, but only 1% of variability for IVP embryos. IVD embryo stage at the start of culture significantly impacted metabolite content. IVD embryo sex did not globally impact composition of the spent culture medium, but the kinetics of decrease of about half of the metabolites differed between male and female blastocysts. Conclusions Standardization of the metabolic properties of IVP embryos invites new questions regarding the impact of embryo biotechnology. Differences in metabolism between male and female IVD embryos are highly transient during the morula-blastocyst stages.</div
Radiocarbon dating of iron reinforcements of Notre-Dame de Paris cathedral. An original contribution to the chronology of the construction and restauration phases
No full textInternational audienceIron reinforcements of Notre-Dame de Paris cathedral are a source of data for the interpretation of gothic architecture. The radiocarbon dating of these metal structures can provide information on the chronology of the different construction periods of the building as well as revealing potential recycling during restoration phases. In addition, this method coupled with archaeometallurgical and chemical analyses can illuminate the roles played by iron in the strategy of the monument erection.Among iron artefacts in the cathedral Notre-Dame de Paris are found staples in the masonry of the tribunes, nave, aisles and upper walls. The restoration works also reveal various tie-rods, dowels, ridge caps and framing irons such as nails, bolted rods or keyed dowels. M. L’Héritier et al. [1] performed the radiocarbon dating of six staples: two of which were retrieved from the tribunes and four from the upper walls. These initial findings revealed that the staples from the tribunes are older than those from the upper walls, and it coincides with the cathedral’s construction phases (middle of the 12th century and beginning of the 13th century). According to the experimental procedure developed by S. Leroy et al. [2] for Bourges and Beauvais cathedrals’ iron reinforcements, 26 additional iron armatures were dated. This approach was adopted to ensure the consistency and reliability of the results between the two previously described corpuses and the parts of the cathedral recently dated. According to the first data obtained for the new artefacts, it can be confirmed that these reinforcements are primarily from the medieval construction phase of Notre-Dame de Paris, thereby confirming the metallographic observation. Two of these artefacts appear to be more recent and could be examples of later restoration work of the monument.Radiocarbon analyses, coupled with metallographic and archaeometric studies, provide a deeper understanding of this gothic monument and more precisely of the buildings techniques through the use of iron reinforcements.[1] L’Héritier M., Azéma A., Sylvilay D., Delqué-Kolic E., Beck L.., Guillot I., Bernard M., Dillmann P.. 2023. Notre-Dame de Paris: The first iron lady? Archaeometallurgical study and dating of the Parisian cathedral iron reinforcements. PLoS ONE 18(3): e0280945. doi: 10.1371/journal.pone.0280945[2] Leroy S., L’Héritier M., Delqué-Kolic E., Dumoulin J.-P., Moreau C., Dillmann P.. 2014. Consolidation or initial design? Radiocarbon dating of ancient iron alloys sheds light on the reinforcements of French Gothic Cathedrals. Journal of Archaeological Science 53: 190-201. doi: 10.1016/j.jas.2014.10.01
Impact of neoadjuvant immunotherapy on postoperative complications in oncoplastic breast cancer surgery
No full textInternational audienceBackground: Neoadjuvant pembrolizumab combined with chemotherapy is now standard treatment for stage II and III triple-negative breast cancer (TNBC). However, its impact on postoperative complications remains underexplored especially in oncoplastic or reconstructive procedures. Methods: A retrospective before-and-after study was conducted at a single institution from January 2019 to May 2023. Patients with early-stage TNBC treated with chemotherapy alone (CT group) or chemotherapy plus pembrolizumab (CT + P group) were included. Postoperative complications (including delayed wound healing, abscesses, hematomas, infections, implant exposure, and skin necrosis) were compared using univariate and multivariate logistic regression. Results: Among 254 patients (CT: n = 136; CT + P: n = 118), the overall complication rate was 15.7 %. No significant difference was observed between groups (p = 0.061). Delayed wound healing was more frequent in the CT + P group (10 % vs. 3.8 %, p = 0.031). After adjustment, immunotherapy was not independently associated with higher risk (OR 1.27, p = 0.5). Oncoplastic surgeries were associated with higher complication rates in univariate analysis but not in multivariate analysis (OR 1.74, p = 0.2). Complications were more frequent when surgery occurred <14 or >30 days post-treatment (p = 0.029), especially among CT + P patients (interaction p = 0.01). Conclusion: Neoadjuvant pembrolizumab does not significantly increase postoperative complications. Surgical timing appears to be a modifiable factor influencing outcomes.</div